Pembrolizumab (Keytruda)

Number: 0890

Policy

Aetna considers pembrolizumab (Keytruda) medically necessary for the following indications:

  • Urothelial carcinoma (Transitional cell carcinoma) 

    • Bladder cancer - as a single agent for 

      • first-line systemic therapy in cisplatin ineligible persons whose tumors express PD-L1 (defined as a Combined Positive Score (CPS) greater than or equal to 10) or in persons who are not eligible for any platinum-containing chemotherapy regardless of PD-L1 status for

        • – stage II or stage IIIA where tumor is present following reassessment of tumor status 2-3 months after primary treatment with concurrent chemoradiotherapy; or
        • – stage IIIB or Stage IV; or

      • subsequent systemic therapy in persons who have disease progression during or following platinum-containing chemotherapy or within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy for

        • – stage IIIB or stage IV; or

      • metastatic or local recurrence post cystectomy

    • Primary carcinoma of the urethra as a single agent for 

      • recurrent or metastatic disease as

        • – first-line systemic therapy in cisplatin ineligible persons whose tumors express PD-L1 (defined as a CPS greater than or equal to 10) or in persons who are not eligible for any platinum-containing chemotherapy regardless of PD-L1 status; or
        • – subsequent systemic therapy in persons who have disease progression during or following platinum-containing chemotherapy or within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy;

      • primary treatment of clinical stage T3-4, cN1-2 disease or cN1-2 palpable inguinal lymph nodes as

        • – first-line therapy in cisplatin ineligible persons whose tumors express PD-L1 (defined as a CPS greater than or equal to 10) or in persons who are not eligible for any platinum-containing chemotherapy regardless of PD-L1 status

    • Upper GU tract tumors as a single agent for metastatic disease as

      • first-line systemic therapy in cisplatin ineligible persons whose tumors express PD-L1 (defined as a CPS greater than or equal to 10) or in persons who are not eligible for any platinum-containing chemotherapy regardless of PD-L1 status; or
      • subsequent systemic therapy in persons who have disease progression during or following platinum-containing chemotherapy or within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy

    • Urothelial carcinoma of the prostate - as a single agent for metastatic disease as

      • first-line systemic therapy in cisplatin ineligible persons whose tumors express PD-L1 (defined as a CPS greater than or equal to 10) or in persons who are not eligible for any platinum-containing chemotherapy regardless of PD-L1 status; or
      • subsequent systemic therapy in persons who have disease progression during or following platinum-containing chemotherapy or within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy.

  • Colorectal cancer, small bowel adenocarcinoma, appendiceal carcinoma, and anal adenocarcinoma

    (defective mismatch repair/high microsatellite instability [dMMR/MSI-H] only) - as a single agent for



    • Primary treatment for unresectable metachronous metastases and previous adjuvant FOLFOX (fluorouracil, leucovorin, and oxaliplatin) or CapeOX (capecitabine and oxaliplatin) within the past 12 months; or
    • Initial therapy for unresectable advanced or metastatic disease who are not appropriate for intensive therapy; or
    • Subsequent therapy (if nivolumab or pembrolizumab not previously given) for unresectable advanced or metastatic disease following previous oxaliplatin- irinotecan- and/or fluoropyrimidine-based therapy.

  • Anal Carcinoma

    - as a single agent for metastatic disease as second-line therapy. 

  • Classical Hodgkin lymphoma

    -  as a single agent for

    • Adult and pediatric members with refractory disease, or who have relapsed after 3 or more prior lines of therapy; or
    • Palliative therapy for older adults greater than 60 years of age with refractory disease, or who have relapsed after 3 or more prior lines of therapy.
  • Cutaneous Melanoma

    • First-line therapy as a single agent for metastatic or unresectable disease; or
    • Second-line or subsequent therapy as a single agent for metastatic or unresectable disease after disease progression or maximum clinical benefit from BRAF targeted therapy
       
      • if anti PD-1 therapy checkpoint inhibitor immunotherapy was not previously used; or
      • as re-induction therapy if prior checkpoint inhibitor immunotherapy resulted in disease control (complete response, partial response, or stable disease) and no residual toxicity, and disease progression/relapse occurred more than 3 months after treatment discontinuation; or
         
    • Adjuvant treatment as a single agent
       
      • for stage III sentinel lymph node (SLN) positive disease following nodal basin ultrasound surveillance or complete lymph node dissection (CLND); or
      • for stage III disease with clinically positive node(s) following wide excision of primary tumor and a complete therapeutic lymph node dissection; or
      • for stage III disease with clinical or microscopic satellite/in-transit metastases if no evidence of disease post-surgery; or
      • for local satellite/in-transit recurrence if no evidence of disease post-surgery; or
      • following CLND and/or complete resection of nodal recurrence; or
      • following complete resection of distant metastatic disease.
         
  • Uveal Melanoma

    - as single agent therapy for metastatic or unresectable disease.

  • Merkel cell carcinoma

    • treatment for distant metastatic disease or disseminated recurrence with or without surgery and/or radiation therapy; or
    • treatment option for persons with recurrent locally advanced disease.
  • Non-small cell lung cancer (NSCLC)

    • As first-line therapy for recurrent, advanced, or metastatic if PD-L1 expression-positive (as defined by  a Tumor Proportion Score (TPS) greater than or equal to 1%) and performance status 0-2 for tumors that are EGFR, ALK, negative or unknown as 

      • single-agent therapy; or
      • in combination with pemetrexed and either carboplatin or cisplatin for nonsquamous cell histology; or
      • in combination with either carboplatin or cisplatin and either paclitaxel or albumin-bound paclitaxel for squamous cell histology.
         
    • As subsequent therapy (if systemic immune checkpoint inhibitors not already given) as single-agent therapy for recurrent, advanced, or metastatic disease in persons with performance status 0-2 and tumors with PD-L1 expression levels (as defined by a TPS greater than or equal to 1%) and no prior progression on a PD-1/PD-L1 inhibitor.

    • In combination with pemetrexed and either carboplatin or cisplatin (if no contraindications to the addition of pembrolizumab for nonsquamous cell histology), or in combination with either cisplatin or carboplatin and either albumin-bound paclitaxel or paclitaxel (if no contraindications to the addition of pembrolizumab for squamous cell histology) for recurrent, advanced or metastatic disease in persons with performance status 0-1 as

      • initial systemic therapy for tumors that are EGFR, ALK, ROS1, BRAF negative or unknown, and PD-L1 less than 1% or unknown; or
      • first-line or subsequent therapy for BRAF V600E-mutation positive tumors; or
      • subsequent therapy for sensitizing EGFR mutation-positive tumors and prior erlotinib, afatinib, gefitinib, osimertinib, or dacomitinib therapy; or
      • subsequent therapy for ALK rearrangement-positive tumors and prior crizotinib, ceritinib, alectinib, or brigatinib therapy; or
      • subsequent therapy for ROS1 rearrangement-positive tumors and prior crizotinib or ceritinib therapy; or
      • subsequent therapy for PD-L1 expression-positive (greater than or equal to 50%) tumors and EGFR, ALK, negative or unknown, and no prior platinum-doublet chemotherapy.

    • As continuation maintenance therapy for recurrent, advanced, or metastatic disease for PD-L1 expression-positive (as defined by  a Tumor Proportion Score (TPS) greater than or equal to 1%) tumors in persons with performance status 0-2, who achieve tumor response or stable disease following initial systemic therapy

      • in combination with pemetrexed if given first line as part of a pembrolizumab/pemetrexed and either cisplatin or carboplatin regimen for tumors of nonsquamous cell histology; or
      • as single-agent continuation if given first-line in combination with either cisplatin or carboplatin and either paclitaxel or albumin-bound paclitaxel for squamous cell histology; or
         
    • As continuation maintenance therapy for recurrent, advanced or metastatic disease for PD-L1 expression positive (greater than or equal to 1%) tumors that are EGFR, ALK negative or unknown and no contraindications to the addition of pembrolizumab or atezolizumab and performance status 0-2, who achieve tumor response or stable disease following systemic or first-line therapy
  • Head and neck cancer

    • As a single agent first-line therapy for very advanced non-nasopharyngeal head and neck squamous cell carcinoma that is PD-L1 positive in

      • Newly diagnosed T4b, any N, M0 disease, unresectable nodal disease with no metastases, or for persons who are unfit for surgery and performance status (PS) 3
      • Metastatic (M1) disease at initial presentation or recurrent/persistent disease with distant metastases, or unresectable locoregional recurrence or second primary with prior radiation therapy (RT) and PS 0-2
      • Unresectable locoregional recurrence without prior RT and PS 3.

    • As a single agent second-line or subsequent therapy for very advanced non-nasopharyngeal head and neck squamous cell carcinoma with disease progression on or after platinum-containing chemotherapy, or for previously treated PD-L1 positive recurrent or metastatic nasopharyngeal cancer

      • Newly diagnosed T4b, any N, M0 disease, unresectable nodal disease with no metastases, or for persons who are unfit for surgery and performance status (PS) 3
      • Metastatic (M1) disease at initial presentation or recurrent/persistent disease with distant metastases, or unresectable locoregional recurrence or second primary with prior radiation therapy (RT) and PS 0-2
      • Unresectable locoregional recurrence without prior RT and PS 3.

  • Solid tumors

    - for the treatment of persons with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair deficient solid tumors that have progressed following prior treatment and who have no satisfactory alternative treatment options.

  • Primary Cutaneous Lymphomas

    • Mycosis Fungoides/Sézary Syndrome - as second-line systemic therapy for
       
      • stage 1A relapsed or persistent MF with B1 blood involvement, with or without skin-directed therapy; or 
      • stage IB-IIA relapsed or persistent MF with B1 blood involvement, with or without skin-directed therapy; or
      • stage IIB MF with limited tumor lesions refractory to multiple previous therapies or progression, with or without skin-directed therapies; or
      • stage IIB relapsed or refractory MF with generalized tumor lesions, with or without skin-directed therapies; or
      • stage IIB MF with generalized tumor lesions refractory to multiple previous therapies or progression; or
      • stage III relapsed or persistent MF, with or without skin-directed therapies; or
      • stage III MF refractory to multiple previous therapies; or
      • stage IV relapsed or persistent Sezary syndrome; or 
      • stage IV non Sezary or visceral disease (solid organ) that is relapsed or persistent, with or without radiation therapy for local control; or
      • large cell transformation (LCT) with limited cutaneous lesions that is refractory to multiple previous therapies; or
      • LCT relapsed or persistent with generalized cutaneous or extracutaneous lesions, with or without skin-directed therapy
         
    • Mycosis Fungoides/Sézary Syndrome - as primary therapy for
       
      • stage III MF
      • stage IV Sezary syndrome
         
    • Primary Cutaneous CD30+ T-Cell Lymphoproliferative Disorders - as a single agent for relapsed/refractory 
       
      • primary cutaneous anaplastic large cell lymphoma (ALCL) with multifocal lesions; or
      • cutaneous ALCL with regional nodes (excludes systemic ALCL).
  • T-Cell Lymphomas

    • Extranodal NK/T-Cell Lymphoma, nasal type in

      • relapsed/refractory disease following additional therapy with clinical trial, combination chemotherapy regimen (asparaginase-based), or best supportive care.

  • Esophageal, esophagogastric junction (EGJ), and gastric cancer

    - as palliative therapy for persons who are not surgical candidates or have unresectable locally advanced, recurrent, or metastatic disease and Karnofsky performance score greater than or equal to 60% or ECOG performance score less than or equal to 2 as
     

    • Second-line or subsequent therapy as a single agent for microsatellite instability-high (MSI-H) or deficient mismatch repair (dMMR) esophageal, EGJ adenocarcionoma, and gastric adenocarcinoma tumors; or
    • Second-line or subsequent therapy for esophageal squamous cell carcinoma, esophagel adenocarcinoma, and esophagogastric junction adenocarcinoma that expresses PD-L1 (defined as a CPS greater than or equal to 10); or
    • Third-line or subsequent therapy as a single agent for PD-L1 positive (defined as a CPS greater than or equal to 1) gastric, esophageal and EGJ adenocarcinoma.
       
  • Primary mediastinal large B-cell lymphoma (PMBCL)

    - as treatment for relapsed or refractory disease.
     

  • Cervical Cancer

    - as second-line therapy as a single agent for recurrent or metastatic disease for

    • microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) tumors; or
    • Disease progression on or after chemotherapy for tumors that express PD-L1 (defined as a Combined Positive Score (CPS) greater than or equal to 1),
       
  • Malignant Pleural Mesothelioma

    - as a single agent for

    • Subsequent systemic therapy for epithelial, sarcomatoid, mixed type,
       
  • Brain Metastases

    - as a single agent therapy in brain metastases in melanoma or non-small cell lung cancer for

    • Newly diagnosed limited brain metastases in select persons; or
    • Recurrent limited or extensive brain metastases.
  • Hepatobiliary Cancers (gallbladder, intrahepatic/extrahepatic cholangiocarcinoma)  

    • as a single agent for primary treatment for unresectable or metastatic disease that is microsatellite instability-high (MSI-H) and/or deficient mismatch repair (dMMR); or
    • as a single agent for treatment for resected gross residual disease that is microsatellite instability-high (MSI-H) and/or deficient mismatch repair (dMMR).
       
  • Hepatobiliary Cancers (hepatocellular)

    - as a single agent for members who received previous treatment with sorafenib (Child-Pugh Class A only) who
     

    • are nontransplant candidates with unresectable disease;or
    • are inoperable by performance status or comorbidity, or have local disease or local disease with minimal extrahepatic disease only; or
    • have extensive liver tumor burden or metastatic disease.
       
  • Neuroendocrine and Adrenal Gland Tumors

    • Adrenal gland tumor - for persons with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) adrenocortical tumors that have progressed following prior treatment and who have no satisfactory alternative treatment options; or
    • Poorly Differentiated (High Grade)/Large or Small Cell - for persons with mismatch repair-deficient (dMMR) or microsatellite instability-high (MSI-H) tumors that have progressed following prior treatment with no satisfactory alternative treatment options .
       
  • Bone Cancer (chondrosarcoma, Ewing Sarcoma, Osteosarcoma) 

    - as a single agent for persons with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) tumors that have progressed following prior treatment and who have no satisfactory alternative treatment options.
     

  • Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma 

    - as a single agent or in combination with ibrutinib for treatment of histologic (Richter's) transformation to diffuse large B-cell lymphoma (clonally related or unknown clonal status) for persons with del(17p)/TP53 mutation or who are chemotherapy refractory and unable to receive chemoimmunotherapy.
     

  • Endometrial Cancer

    - for persons with recurrent, metastatic, or high-risk microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) tumors that have progressed following prior cytotoxic chemotherapy.
     

  • Epithelial Ovarian/Fallopian Tube/Primary Peritoneal Cancers

    - as a single agent for recurrent or persistent microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) tumors.
     

  • Gestational Trophoblastic Neoplasia

    - as a single agent in persons with
     

    • Recurrent or progressive intermediate trophoblastic tumor (placental site trophoblastic tumor or epithelioid trophoblastic tumor) following treatment with a platinum/etoposide-containing regimen; or
    • Methotrexate-resistant high-risk disease.
       
  • Pancreatic Adenocarcinoma

    - as a single agent subsequent therapy for locally advanced or metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) tumors in members with good performance status (ECOG PS 0-1) and disease progression.
     

  • Penile Cancer

    - as a single agent for subsequent systemic therapy for select persons with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) tumor that has progressed following prior treatment and who have no satisfactory alternative treatment options.
     

  • Prostate Cancer

    - as a single agent for subsequent therapy for persons who have progressed through at least one line of systemic therapy for castration-resistant distant metastatic (M1) disease that is microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR), if pembrolizumab not previously received.
     

  • Small Cell Lung Cancer

    - as a single agent for subsequent systemic therapy for persons with performance status 0-2 for
     

     
    • Relapse within 6 months following complete or partial response or stable disease with initial treatment; or
    • Primary progressive disease.
  • Soft Tissue Sarcoma

    • as a single agent for the treatment of alveolar soft part sarcoma (ASPS)
    • as a single agent for the treatment of metastatic undifferentiated pleomorphic sarcoma 
       
  • Testicular Cancer

    - as a single agent for palliative therapy in persons with microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) tumors that have progressed following prior high-dose chemotherapy or third-line therapy.
     

  • Vulvar Cancer

    - as a single agent for second-line therapy under certain circumstances for advanced, recurrent or metastatic disease in persons with 
      

     
    • microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) tumors; or
    • disease progression on or after chemotherapy in persons whose tumors express PD-L1 (Combined Positive Score ≥1) as determined by an FDA-approved test.

  • Kidney Cancer (clear cell histology)

    - in combination with axitinib for relapsed or stage IV disease as 
     

    • preferred first-line therapy for poor, intermediate, or favorable risk;or
    • subsequent therapy

Aetna considers continued pembrolizumab treatment experimental and investigational if disease progresses while on pembrolizumab (Keytruda). 

Aetna considers pembrolizumab experimental and investigational if disease progresses while on prior anti-PD-1 therapy (e.g., nivolumab (Opdivo), atezolizumab (Tecentriq), avelumab (Bavencio), and durvalumab (Imfinzi)).

Aetna considers pembrolizumab experimental and investigational for all other indications including the following (not an all-inclusive list) unless it is used in solid tumors for the treatment of persons with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair deficient solid tumors that have progressed following prior treatment and who have no satisfactory alternative treatment options:

  • Breast cancer
  • Central nervous system tumors (e.g. glioblastoma, astrocytoma)
  • Lacrimal gland cancer
  • Multiple myeloma
  • Salivary tumors
  • Certain types of bone cancer (e.g., giant cell tumor of bone or chordomas; other than chondrosarcomas, Ewing sarcomas, and osteosarcomas) 

Background

Pembrolizumab is a programmed death receptor-1 (PD-1) blocking monoclonal antibody that works by preventing the interaction between PD-1 and the PD-L1 and PD-L2 ligands. It is indicated for the treatment of certain types of melanoma, non-small cell lung cancer (NSCLC), gastric cancer, Hodgkin lymphoma, head and neck cancer, hepatocellular cancer, urothelial carcinoma, microsatellite instability-high (MSI-H) or mismatch repair deficient solid tumors, cervical cancer, primary mediastinal large B-cell lymphoma (PMBCL), and Merkel cell carcinoma.

Melanoma

Melanoma is a serious form of skin cancer that arises from melanocytes; however, in rare instances, it can originate in the eye or other non-skin organs.  Risk factors for melanoma entail freckling, genetic factors, history of sunburns, light skin or eye color, poor tanning ability, sun exposure, as well as tanning bed use.  About 80 % of melanomas are detected in a localized stage.  When detected early, the 5-year survival rate of melanoma is 98.5 %.  However, when melanoma is diagnosed after distant metastasis, the 5-year survival rate decreases to 15 % with a median survival between 8 and 9 months.  Tumor thickness, along with nodal involvement, is a prognostic factor for melanoma.  As tumor thickness increases to greater than 1.0 mm, the survival rate is reduced by 50 %.  The incidence of melanoma is rapidly increasing.  According to the National Cancer Institute (NCI), melanoma is the leading cause of death from skin disease.  Approximately 76.100 new cases of melanoma will be diagnosed in the United States in 2014 and about 9,700 people will die from the disease.  Treatments of melanoma include chemotherapy, immunotherapy, radiation therapy, surgery, as well as vaccine therapy (NCI, 2014).  Moreover, the National Comprehensive Cancer Network (NCCN)’s clinical practice guideline on Melanoma” (Version 4.2014) states that little consensus exists regarding the optimal standard chemotherapy for patients with metastatic melanoma.  Enrollment in a clinical trial, if available, is the preferred choice.

The past several years were marked by the emergence of new molecules for the treatment of metastatic cutaneous melanoma with a significant benefit on the survival -- ipilimumab (Yervoy), peginterferon alfa-2b (PEG-Intron) and vemurafenib (Zelboraf) were approved by the Food and Drug Administration (FDA) in 2011; dabrafenib (Tafinlar) and trametinib (Mekinist) were approved in 2013.  More recently, much attention has been devoted to the blockade of programmed death 1 (PD-1) signaling to activate an immune response to cancer.  PD-1, a protein expressed on T cells, is a member of the CD28 superfamily, and it transmits co-inhibitory signals upon engagement with its ligands PD-L1 and PD-L2.  Accumulating evidence suggests that the PD-1 system plays pivotal roles in the regulation of autoimmunity, transplantation immunity, infectious immunity, and tumor immunity.  Because the interaction of PD-1 with its ligands occurs in the effector phase of killer T cell responses in peripheral blood, anti-PD-1 and anti-PD-L1 monoclonal antibodies are ideal as specific agents to augment T cell responses to tumors with fewer adverse events than with the inhibition of CTLA-4, because the interaction of CTLA-4 with its ligands occurs in the priming phase of T cell responses within lymph nodes.  In recent phase I clinical trials, objective responses were observed in patients with melanoma, renal cell carcinoma, and non-small cell lung cancer (NSCLC) who underwent immunotherapy with an anti-PD-1 monoclonal antibody.  In addition, the anti-tumor activity of an anti-PD-L1 monoclonal antibody was observed in patients with melanoma, renal cell carcinoma, NSCLC, and ovarian cancer (Tanaka and Okamura, 2013).  

Pembrolizumab (formerly known as lambrolizumab; MK-3475), a negative regulator of T-cell effector mechanisms that limits immune responses against cancer, is an agent that targets the PD-1 receptor.  Blockade of interactions between PD-1 and PD-L1 enhances immune function in-vitro and mediates anti-tumor activity in pre-clinical models.  Moreover, pembrolizumab has shown potent anti-tumor activity at different doses and schedules in patients with melanoma. 

Keytruda (pembrolizumab) is indicated for the treatment of patients with unresectable or metastatic melanoma and for metastatic non-small cell lung cancer where disease progression on or following chemotherapy and patients with EGFR or ALK genomic tumor aberrations should have disease progression after failure of prior approved therapy for these aberrations.

Binding of the programmed death-1 (PD-1) ligands, PD-L1 and PD-L2, to the PD-1 receptor found on T cells, inhibits T cell proliferation and cytokine production. Upregulation of PD-1 ligands occurs in some tumors and signaling through this pathway can contribute to inhibition of active T-cell immune surveillance of tumors. Keytruda (pembrolizumab) is a monoclonal antibody that binds to the PD-1 receptor and blocks its interaction with PD-L1 and PD-L2, releasing PD-1 pathway-mediated inhibition of the immune response, including the anti-tumor immune response. In syngeneic mouse tumor models, blocking PD-1 activity resulted in decreased tumor growth.

Hamid et al (2013) tested the anti-PD-1 antibody lambrolizumab (previously known as MK-3475) in patients with advanced melanoma.  These investigators administered lambrolizumab intravenously at a dose of 10 mg/kg body weight every 2 or 3 weeks or 2 mg/kg every 3 weeks in patients with advanced melanoma, both those who had received prior treatment with ipilimumab and those who had not.  Tumor responses were assessed every 12 weeks.  A total of 135 patients with advanced melanoma were treated.  Common adverse events (AEs) attributed to treatment were fatigue, rash, pruritus, and diarrhea; most of the AEs were low grade.  The confirmed response rate across all dose cohorts, evaluated by central radiologic review according to the Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1, was 38 % (95 % confidence interval [CI]: 25 to 44), with the highest confirmed response rate observed in the cohort that received 10 mg/kg every 2 weeks (52 %; 95 % CI: 38 to 66).  The response rate did not differ significantly between patients who had received prior ipilimumab treatment and those who had not (confirmed response rate, 38 % [95 % CI: 23 to 55] and 37 % [95 % CI: 26 to 49], respectively).  Responses were durable in the majority of patients (median follow-up of 11 months among patients who had a response); 81 % of the patients who had a response (42 of 52) were still receiving treatment at the time of analysis in March 2013.  The overall median progression-free survival (PFS) among the 135 patients was longer than 7 months.  The authors concluded that in patients with advanced melanoma, including those who had had disease progression while they had been receiving ipilimumab, treatment with lambrolizumab resulted in a high rate of sustained tumor regression, with mainly grade 1 or 2 toxic effects.

In an open-label, international, multi-center, expansion cohort of a phase 1 clinical trial, Robert and colleagues (2014) compared the safety and effectiveness of pembrolizumab at doses of 2 mg/kg and 10 mg/kg every 3 weeks in patients with ipilimumab-refractory advanced melanoma.   Patients (aged greater than or equal to 18 years) with advanced melanoma whose disease had progressed after at least 2 ipilimumab doses were randomly assigned with a computer-generated allocation schedule (1:1 final ratio) to intravenous pembrolizumab at 2 mg/kg every 3 weeks or 10 mg/kg every 3 weeks until disease progression, intolerable toxicity, or consent withdrawal.  Primary end-point was overall response rate (ORR) assessed with RECIST, version 1.1 by independent central review.  Analysis was done on the full-analysis set (all treated patients with measurable disease at baseline).  A total of 173 patients received pembrolizumab 2 mg/kg (n = 89) or 10 mg/kg (n = 84).  Median follow-up duration was 8 months.  Overall response rate was 26 % at both doses: 21 of 81 patients in the 2 mg/kg group and 20 of 76 in the 10 mg/kg group (difference 0 %, 95 % CI: -14 to 13; p = 0·96).  Treatment was well-tolerated, with similar safety profiles in the 2 mg/kg and 10 mg/kg groups and no drug-related deaths.  The most common drug-related AEs of any grade in the 2 mg/kg and 10 mg/kg groups were fatigue (29 [33 %] versus 31 [37 %]), pruritus (23 [26 %] versus 16 [19 %]), and rash (16 [18 %] versus 15 [18 %]).  Grade-3 fatigue, reported in 5 (3 %) patients in the 2 mg/kg pembrolizumab group, was the only drug-related grade 3 to 4 AE reported in more than 1 patient.  The authors concluded that these findings suggested that pembrolizumab at a dose of 2 mg/kg or 10 mg/kg every 3 weeks might be an effective treatment in patients for whom there are few effective treatment options.

On September 4, 2014, the FDA approved pembrolizumab (Keytruda) for the treatment of patients with advanced or unresectable melanoma who are no longer responding to other drugs.  Keytruda is the first approved drug that blocks the PD-1 pathway, which restricts the body’s immune system from attacking melanoma cells.  Keytruda is intended for use following treatment with ipilimumab.  For melanoma patients whose tumors express a gene mutation called BRAF V600, Keytruda is intended for use after treatment with ipilimumab and a BRAF inhibitor, a therapy that blocks activity of BRAF gene mutations.  The FDA granted Keytruda breakthrough therapy designation because the sponsor demonstrated through preliminary clinical evidence that the drug may offer a substantial improvement over available therapies.  It also received priority review and orphan product designation.  Priority review is granted to drugs that have the potential, at the time the application was submitted, to be a significant improvement in safety or effectiveness in the treatment of a serious condition.  Orphan product designation is given to drugs intended to treat rare diseases.  The effectiveness of Keytruda was established in 173 subjects with advanced melanoma whose disease progressed after prior treatment.  All participants were treated with Keytruda, either at the recommended dose of 2 mg/kg or at a higher dose of 10 mg/kg.  In the half of the participants who received Keytruda at the recommended dose of 2 mg/kg, approximately 24 % had their tumors shrink.  This effect lasted at least 1.4 to 8.5 months and continued beyond this period in most patients.  A similar percentage of patients had their tumor shrink at the 10 mg/kg dose.  The most common side effects of Keytruda were fatigue, cough, nausea, pruritus, rash, decreased appetite, constipation, arthralgia and diarrhea. Keytruda also has the potential for severe immune-mediated side effects involving healthy organs, including the lung, colon, hormone-producing glands and liver, occurred uncommonly.

On February 15, 2019, the Food and Drug Administration approved pembrolizumab (KEYTRUDA, Merck) for the adjuvant treatment of patients with melanoma with involvement of lymph node(s) following complete resection. Approval was based on EORTC1325/KEYNOTE‑054 (Eggermont 2018), a randomized, double-blind, placebo-controlled, trial in 1019 patients with completely resected, stage IIIA (>1 mm lymph node metastasis), IIIB or IIIC melanoma (AJCC 7th ed). Patients with mucosal or ocular melanoma were not eligible. Eggermont et al (2018; NCT02362594) stated that the programmed death 1 (PD-1) inhibitor pembrolizumab has been found to prolong progression-free and overall survival among patients with advanced melanoma. This was a multicenter, randomized, double-blind, placebo-controlled trial to evaluate pembrolizumab as adjuvant therapy in patients with completely resected stage IIIA (>1 mm lymph node metastasis), IIIB or IIIC melanoma. Patients were randomly assigned (with stratification according to cancer stage and geographic region) to receive 200 mg of pembrolizumab (514 patients) or placebo (505 patients) intravenously every 3 weeks for a total of 18 doses (approximately 1 year) or until disease recurrence or unacceptable toxic effects occurred. Recurrence-free survival (RFS) in the overall intention-to-treat population and in the subgroup of patients with cancer that was positive for the PD-1 ligand (PD-L1) were the primary end points. RFS was defined as the time between the date of randomization and first recurrence (local, regional, or distant metastasis) or death from any cause, whichever occurred first. Safety was also evaluated. At a median follow-up of 15 months, pembrolizumab was associated with significantly longer recurrence-free survival than placebo in the overall intention-to-treat population (1-year rate of recurrence-free survival, 75.4% [95% confidence interval {CI}, 71.3 to 78.9] vs. 61.0% [95% CI, 56.5 to 65.1]; hazard ratio for recurrence or death, 0.57; 98.4% CI, 0.43 to 0.74; P<0.001) and in the subgroup of 853 patients with PD-L1-positive tumors (1-year rate of recurrence-free survival, 77.1% [95% CI, 72.7 to 80.9] in the pembrolizumab group and 62.6% [95% CI, 57.7 to 67.0] in the placebo group; hazard ratio, 0.54; 95% CI, 0.42 to 0.69; P<0.001). Adverse events of grades 3 to 5 that were related to the trial regimen were reported in 14.7% of the patients in the pembrolizumab group and in 3.4% of patients in the placebo group. There was one treatment-related death due to myositis in the pembrolizumab group. The authors concluded that as adjuvant therapy for high-risk stage III melanoma, 200 mg of pembrolizumab administered every 3 weeks for up to 1 year resulted in significantly longer recurrence-free survival than placebo, with no new toxic effects identified.

According to the Prescribing Information, Keytruda (pembrolizumab) is indicated for the treatment of patients with unresectable or metastatic melanoma and for the adjuvant treatment of patients with melanoma with involvement of lymph node(s) following complete resection. 

The National Comprehensive Cancer Network Drugs & Biologics Compendium (NCCN, 2019) states that pembrolizumab is a preferred single agent for metastatic or unresectable melanoma as:

  • First-line therapy
  • Second-line or subsequent therapy after disease progression or maximum clinical benefit from BRAF targeted therapy if anti PD-1 therapy not previously used.
  • Second-line of subsequent therapy after disease progression or maximum clinical benefit from BRAF targeted therapy if prior anti-PD-1 therapy resulted in disease control (complete response, partial response, or stable disease) and no residual toxicity, and disease progression/relapse occurred >3 months after treatment discontinuation.
  • Adjuvant treatment as a single agent
     
    • for stage III sentinel lymph node (SLN) positive disease following nodal basin ultrasound surveillance or complete lymph node dissection (CLND); or
    • for stage III disease with clinically positive node(s) following wide excision of primary tumor and a complete therapeutic lymph node dissection; or
    • for stage III disease with clinical or microscopic satellite/in-transit metastases if no evidence of disease post-surgery; or
    • for local satellite/in-transit recurrence if no evidence of disease post-surgery; or
    • following CLND and/or complete resection of nodal recurrence; or
    • following complete resection of distant metastatic disease.

NCCN (2015) guidelines state that, "while pembrolizumab and nivolumab are indicated for disease progression after treatment with ipilimumab and, if BRAF V600 mutation positive, a BRAF inhibitor, there is consensus among the NCCN panel that both drugs have higher response rates and less toxicity compared to ipilimumab, and that both drugs should be included as options for first-line treatment." The NCCN guidelines (NCCN, 2014) state that pembrolizumab may cause immune-mediated adverse reactions. Depending on the severity of the reaction, pembrolizumab should be discontinued and corticosteroids administered for immune-mediated: pneumonitis, colitis, hepatitis, hypophysitis, nephritis, and hyperthyroidism. For patients with pre-existent hypophysitis due to ipilimumab, pembrolizumab may be administered if patients are on appropriate physiologic replacement endocrine therapy.

Warnings/Precautions:

  • Immune-Mediated Pneumonitis: Pneumonitis occurred in 12 (2.9%) of 411 melanoma patients, including Grade 2 or 3 cases in 8 (1.9%) and 1 (0.2%) patients, respectively, receiving Keytruda (pembrolizumab) in Trial 1. The median time to development of pneumonitis was 5 months (range 0.3 weeks-9.9 months). The median duration was 4.9 months (range 1 week-14.4 months). Five of eight patients with Grade 2 and the one patient with Grade 3 pneumonitis required initial treatment with high-dose systemic corticosteroids (greater than or equal to 40 mg prednisone or equivalent per day) followed by a corticosteroid taper. The median initial dose of high-dose corticosteroid treatment was 63.4 mg/day of prednisone or equivalent with a median duration of treatment of 3 days (range 1-34) followed by a corticosteroid taper. Pneumonitis led to discontinuation of Keytruda (pembrolizumab) in 3 (0.7%) patients. Pneumonitis completely resolved in seven of the nine patients with Grade 2-3 pneumonitis.
  • Immune-Mediated Colitis: Colitis (including microscopic colitis) occurred in 4 (1%) of 411 patients, including Grade 2 or 3 cases in 1 (0.2%) and 2 (0.5%) patients, respectively, receiving Keytruda (pembrolizumab) in Trial 1. The median time to onset of colitis was 6.5 months (range 2.3-9.8). The median duration was 2.6 months (range 0.6 weeks-3.6 months). All three patients with Grade 2 or 3 colitis were treated with high-dose corticosteroids (greater than or equal to 40 mg prednisone or equivalent per day) with a median initial dose of 70 mg/day of prednisone or equivalent; the median duration of initial treatment was 7 days (range 4-41), followed by a corticosteroid taper. One patient (0.2%) required permanent discontinuation of Keytruda (pembrolizumab) due to colitis. All four patients with colitis experienced complete resolution of the event.
  • Immune-Mediated Hepatitis: Hepatitis (including autoimmune hepatitis) occurred in 2 (0.5%) of 411 patients, including a Grade 4 case in 1 (0.2%) patient, receiving Keytruda (pembrolizumab) in Trial 1. The time to onset was 22 days for the case of Grade 4 hepatitis which lasted 1.1 months. The patient with Grade 4 hepatitis permanently discontinued Keytruda (pembrolizumab) and was treated with high-dose (greater than or equal to 40 mg prednisone or equivalent per day) systemic corticosteroids followed by a corticosteroid taper. Both patients with hepatitis experienced complete resolution of the event.
  • Immune-Mediated Hypophysitis: Hypophysitis occurred in 2 (0.5%) of 411 patients, consisting of one Grade 2 and one Grade 4 case (0.2% each), in patients receiving Keytruda (pembrolizumab) in Trial 1. The time to onset was 1.7 months for the patient with Grade 4 hypophysitis and 1.3 months for the patient with Grade 2 hypophysitis. Both patients were treated with high-dose (greater than or equal to 40 mg prednisone or equivalent per day) corticosteroids followed by a corticosteroid taper and remained on a physiologic replacement dose.
  • Renal Failure and Immune-Mediated Nephritis: Nephritis occurred in 3 (0.7%) patients, consisting of one case of Grade 2 autoimmune nephritis (0.2%) and two cases of interstitial nephritis with renal failure (0.5%), one Grade 3 and one Grade 4. The time to onset of autoimmune nephritis was 11.6 months after the first dose of Keytruda (pembrolizumab) (5 months after the last dose) and lasted 3.2 months; this patient did not have a biopsy. Acute interstitial nephritis was confirmed by renal biopsy in two patients with Grades 3-4 renal failure. All three patients fully recovered renal function with treatment with high-dose corticosteroids (greater than or equal to 40 mg prednisone or equivalent per day) followed by a corticosteroid taper.
  • Immune-Mediated Hyperthyroidism and Hypothyrodism: Hyperthyroidism occurred in 5 (1.2%) of 411 patients, including Grade 2 or 3 cases in 2 (0.5%) and 1 (0.2%) patients, respectively, receiving Keytruda (pembrolizumab) in Trial 1. The median time to onset was 1.5 months (range 0.5-2.1). The median duration was 2.8 months (range 0.9 to 6.1). One of two patients with Grade 2 and the one patient with Grade 3 hyperthyroidism required initial treatment with high-dose corticosteroids (greater than or equal to 40 mg prednisone or equivalent per day) followed by a corticosteroid taper. One patient (0.2%) required permanent discontinuation of Keytruda (pembrolizumab) due to hyperthyroidism. All five patients with hyperthyroidism experienced complete resolution of the event.
  • Hypothyroidism occurred in 34 (8.3%) of 411 patients, including a Grade 3 case in 1 (0.2%) patient, receiving Keytruda (pembrolizumab) in Trial 1. The median time to onset of hypothyroidism was 3.5 months (range 0.7 weeks-19 months). All but two of the patients with hypothyroidism were treated with long-term thyroid hormone replacement therapy. The other two patients only required short-term thyroid hormone replacement therapy. No patient received corticosteroids or discontinued Keytruda (pembrolizumab) for management of hypothyroidism.
  • Immune-mediated skin adverse reactions, including SJS, TEN (some cases with fatal outcome), exfoliative dermatitis, and bullous pemphigoid: , can occur. Monitor patients for suspected severe skin reactions and exclude other causes. Based on the severity of the adverse reaction, withhold or permanently discontinue pembrolizumab and administer corticosteroids. For signs or symptoms of SJS or TEN, withhold pembrolizumab and refer the patient for specialized care for assessment and treatment. If SJS or TEN is confirmed, permanently discontinue pembrolizumab.
  • Other Immune-Mediated Adverse Reactions: The following clinically significant, immune-mediated adverse reactions occurred in less than 1% (unless otherwise indicated) of patients treated with Keytruda (pembrolizumab) in clinical trial: exfoliative dermatitis, uveitis, arthritis (1.5%), myositis, pancreatitis, hemolytic anemia, partial seizures arising in a patient with inflammatory foci in brain parenchyma, adrenal insufficiency, Guillain-Barré syndrome, myasthenia gravis, vasculitis, sarcoidosis and encephalitis. In addition, myelitis and myocarditis were reported in other clinical trials, including cHL, and post-marketing use. Solid organ transplant rejection has been reported in the post-marketing setting in patients treated with pembrolizumab . Treatment with pembrolizumab may increase the risk of rejection in solid organ transplant recipients. Consider the benefit of treatment with pembrolizumab versus the risk of possible organ rejection in these patients.
  • In two randomized clinical trials in patients with multiple myeloma, the addition of pembrolizumab to a thalidomide analogue plus dexamethasone, a use for which no PD-1 or PD-L1 blocking antibody is indicated, resulted in increased mortality. Treatment of patients with multiple myeloma with a PD-1 or PDL1 blocking antibody in combination with a thalidomide analogue plus dexamethasone is not recommended outside of controlled clinical trials.
  • Pregnancy—Category D. Based on its mechanism of action, Keytruda (pembrolizumab) may cause fetal harm when administered to a pregnant woman. Animal models link the PD-1/PDL-1 signaling pathway with maintenance of pregnancy through induction of maternal immune tolerance to fetal tissue. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, apprise the patient of the potential hazard to a fetus. Human IgG4 (immunoglobulins) are known to cross the placenta; therefore, pembrolizumab has the potential to be transmitted from the mother to the developing fetus. Based on its mechanism of action, fetal exposure to pembrolizumab may increase the risk of developing immune-mediated disorders or of altering the normal immune response.

Non-Small Cell Lung Cancer (NSCLC)

Langer (2015) noted that immune checkpoint inhibition as a new treatment approach is undergoing extensive investigation in NSCLC and other malignancies.  Unlike standard chemotherapy or targeted agents, which act directly on the tumor cells, immune checkpoint inhibitors work by restoring the immune system's capacity to eradicate tumors.  Agents currently in active clinical development for lung cancer include ipilimumab, which modulates the cytotoxic T-lymphocyte-associated antigen 4 pathway, and multiple agents targeting the PD-1 pathway, both anti-PD-1 compounds (nivolumab, pembrolizumab [MK-3475]) and those that target PD-L1, a key ligand for PD-1 (BMS-936559, MPDL3280A).  The authors stated that preliminary evidence showed activity for these agents in NSCLC as monotherapy or in combination with chemotherapy.

Asmar and Rizvi (2015) stated that lung cancers are immunogenic tumors that manage to evade the immune system by exploiting checkpoint pathways that render effector T cells anergic.  Inhibition of these checkpoints can restore and invigorate endogenous antitumor T-cell responses.  The immunotherapeutic approach of checkpoint inhibition has become an important treatment option for patients with advanced NSCLC, playing a role that will continue to evolve over the coming years.  The PD-1 inhibitors nivolumab and pembrolizumab have both been shown to induce durable responses and improve survival in a subset of patients with platinum-refractory metastatic HSCLC.

Sgambato and colleagues (2016) noted that the better understanding of immunology and anti-tumor immune responses have prompted the development of novel immunotherapy agents like PD-1 checkpoint inhibitors (anti-PD-1 and anti-PDL-1 antibodies) that improve the capacity of the immune system to acknowledge and delete tumors, including lung cancer.  Currently, 2 anti-PD-1 (nivolumab and pembrolizumab) and 1 anti- PD-L1 (MPDL-3280A) agents are in advanced stages of development in advanced or metastatic NSCLC.  Among these, nivolumab demonstrated a survival benefit versus docetaxel in refractory squamous NSCLC, reporting 41 % reduction in risk of death (median overall survival [OS]: 9.2 versus 6.0 months; ORR: 20 % versus 9 %), and better safety profile than standard-of-care chemotherapy (grade 3 to 4 adverse events: 7 % versus 55 %).  However, the enhancement of immune response to cancer targeting specific immune regulatory checkpoints is associated with a toxicity profile different from that related to traditional chemotherapeutic agents and molecularly targeted therapies.

In a phase I clinical trial, Garon et al (2015) evaluated the safety and effectiveness of programmed cell death 1 (PD-1) inhibition with pembrolizumab in patients with advanced NSCLC.  These researchers also sought to define and validate an expression level of the PD-1 ligand 1 (PD-L1) that is associated with the likelihood of clinical benefit.  They assigned 495 patients receiving pembrolizumab (at a dose of either 2 mg or 10 mg per kilogram of body weight every 3 weeks or 10 mg per kilogram every 2 weeks) to either a training group (182 patients) or a validation group (313 patients).  They assessed PD-L1 expression in tumor samples using immunohistochemical analysis, with results reported as the percentage of neoplastic cells with staining for membranous PD-L1 (proportion score).  Response was assessed every 9 weeks by central review.  Common side effects that were attributed to pembrolizumab were fatigue, pruritus, and decreased appetite, with no clear difference according to dose or schedule.  Among all the patients, the objective response rate was 19.4 %, and the median duration of response was 12.5 months.  The median duration of progression-free survival (PFS) was 3.7 months, and the median duration of overall survival (OS) was 12.0 months.  PD-L1 expression in at least 50 % of tumor cells was selected as the cut-off from the training group.  Among patients with a proportion score of at least 50 % in the validation group, the response rate was 45.2 %.  Among all the patients with a proportion score of at least 50 %, median PFS was 6.3 months; median OS was not reached.  The authors concluded that pembrolizumab had an acceptable side-effect profile and showed anti-tumor activity in patients with advanced NSCLC.  PD-L1 expression in at least 50 % of tumor cells correlated with improved efficacy of pembrolizumab.

On October 2, 2015, the FDA granted accelerated approval for Keytruda (pembrolizumab) to treat patients with advanced (metastatic) NSCLC whose disease has progressed after other treatments and with tumors that express a protein called PD-L1.  Keytruda is approved for use with a companion diagnostic, the PD-L1 IHC 22C3 pharmDx test, the first test designed to detect PD-L1 expression in NSCLC.  The safety of Keytruda was studied in 550 patients with advanced NSCLC.  The most common side effects of Keytruda included fatigue, decreased appetite, shortness of breath or impaired breathing (dyspnea) and cough.  Keytruda also has the potential to cause severe side effects that result from the immune system effect of Keytruda.  The effectiveness of Keytruda for this use was demonstrated in a subgroup of 61 patients enrolled within a larger multi-center, open-label, multi-part study.  The subgroup consisted of patients with advanced NSCLC that progressed following platinum-based chemotherapy or, if appropriate, targeted therapy for certain genetic mutations (ALK or EGFR).  This subgroup also had PD-L1 positive tumors based on the results of the 22C3 pharmDx diagnostic test.  Study participants received 10 mg/kg of Keytruda every 2 or 3 weeks.  The major outcome measure was ORR (percentage of patients who experienced complete and partial shrinkage of their tumors).  Tumors shrank in 41 % of patients treated with Keytruda and the effect lasted between 2.1 and 9.1 months.  In the 550 study participants with advanced NSCLC, severe immune-mediated side effects occurred involving the lungs, colon and hormone-producing glands.  Other uncommon immune-mediated side effects were rash and inflammation of blood vessels (vasculitis).  Women who are pregnant or breast-feeding should not take Keytruda because it may cause harm to a developing fetus or newborn baby.  Across clinical studies, a disorder in which the body's immune system attacks part of the peripheral nervous system (Guillain-Barre syndrome) also occurred.

The FDA approved pembrolizumab in combination with pemetrexed (Alimta) and carboplatin (pem/carbo) for the first-line treatment of metastatic nonsquamous NSCLC, irrespective of PD-L1 expression (Merck, 2017). Under the FDA’s accelerated approval regulations, this indication was approved based on tumor response rate and progression-free survival (PFS). Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

The FDA approval was based on data from KEYNOTE-021, Cohort G1, in 123 previously untreated patients with metastatic nonsquamous NSCLC with no EGFR or ALK genomic tumor aberrations and irrespective of PD-L1 expression (Merck, 2017). The key eligibility criteria for this cohort were locally advanced or metastatic nonsquamous NSCLC, regardless of tumor PD-L1 expression status, and no prior systemic treatment for metastatic disease. Patients with autoimmune disease that required systemic therapy within two years of treatment; a medical condition that required immunosuppression; or who had received more than 30 Gy of thoracic radiation within the prior 26 weeks were ineligible. Patients in KEYNOTE-021G1 were randomized to receive pembrolizumab + pem/carbo (n=60) or pem/carbo alone (n=63). Patients in the pembrolizumab combination arm received pembrolizumab (200 mg), pemetrexed (500 mg/m2), and carboplatin (AUC 5 mg/mL/min) every three weeks for four cycles followed by pembrolizumab every three weeks. In the control arm, patients received pemetrexed (500 mg/m2) and carboplatin (AUC 5 mg/mL/min) alone for four cycles. At the investigator’s discretion, maintenance pemetrexed (500 mg/m2) every three weeks was permitted in both treatment arms. Treatment with pembrolizumab continued until Response Evaluation Criteria in Solid Tumors (RECIST) 1.1-defined progression of disease as determined by blinded independent central review (BICR), unacceptable toxicity, or a maximum of 24 months. Administration of pembrolizumab was permitted beyond RECIST-defined disease progression if the patient was clinically stable and deriving clinical benefit as determined by the investigator.

The major efficacy outcome measure was ORR as assessed by BICR using RECIST 1.1 (Merck, 2017). Additional efficacy outcome measures were PFS as assessed by BICR using RECIST 1.1, duration of response, and overall survival (OS).

Findings from this cohort demonstrated an ORR with pembrolizumab + pem/carbo of 55 percent (95% CI: 42, 68) compared to 29 percent (95% CI: 18, 41) for pem/carbo alone; all responses were partial responses (Merck, 2017). Among patients who received pembrolizumab + pem/carbo, 93 percent had a duration of response of six months or more (range 1.4+ to 13.0+ months) compared to 81 percent who received pem/carbo alone (range 1.4+ to 15.2+ months). In addition, findings demonstrated an improvement in PFS (HR 0.53 [95% CI, 0.31-0.91; p=0.0205]), with a median PFS of 13.0 months (95% CI, 8.3-not estimable) for patients treated with pembrolizumab + pem/carbo compared to 8.9 months (95% CI, 4.4-10.3) with pem/carbo alone.

Exploratory analyses found similar results in patients with or without PD-L1 expression, with an ORR in patients whose tumors did not express PD-L1 (TPS <1%) of 57 percent with pembrolizumab + pem/carbo compared to 13.0 percent with pem/carbo alone; in patients with PD-L1 TPS ≥1%, the ORR was 54 percent with pembrolizumab + pem/carbo compared to 38 percent with pem/carbo alone (Merck, 2017).

The product labeling state that, when administering pembrolizumab in combination with pem/carbo, pembrolizumab should be administered first prior to chemotherapy when given on the same day (Merck, 2017). In metastatic NSCLC, pembrolizumab is approved at a fixed dose of 200 mg administered as an intravenous infusion over 30 minutes every three weeks until disease progression, unacceptable toxicity, or up to 24 months in patients without disease progression; pemetrexed and carboplatin should be administered according to their FDA-approved labels.

In the KEYNOTE-021G1 trial, safety was evaluated in 59 patients who received pembrolizumab + pem/carbo and 62 patients who received pem/carbo alone (Merck, 2017). When pembrolizumab was administered in combination with pemetrexed and carboplatin, pembrolizumab was discontinued in 10% of 59 patients. The most common adverse reaction resulting in discontinuation of pembrolizumab (≥2%) was acute kidney injury (3.4%). Adverse reactions leading to interruption of pembrolizumab occurred in 39% of patients; the most common (≥2%) were fatigue (8%), neutrophil count decreased (8%), anemia (5%), dyspnea (3.4%), and pneumonitis (3.4%).The most common adverse reactions (≥20%) with pembrolizumab compared to carbo/pem alone were fatigue (71% vs 50%), nausea (68% vs 56%), constipation (51% vs 37%), rash (42% vs 21%), vomiting (39% vs 27%), dyspnea (39% vs 21%), diarrhea (37% vs 23%), decreased appetite (31% vs. 23%), headache (31% vs 16%), cough (24% vs 18%), dizziness (24%vs 16%), insomnia (24% vs 15%), pruritus (24% vs 4.8%), peripheral edema (22% vs 18%), dysgeusia (20% vs 11%), alopecia (20% vs 3.2%), upper respiratory tract infection (20% vs 3.2%), and arthralgia (15% vs 24%). The study was not designed to demonstrate a statistically significant difference in adverse reaction rates for pembrollizumab plus chemotherapy, as compared to chemotherapy alone, for any specified adverse reaction.

The NCCN Drugs and Biologics Compendium (2018) recommends pembrolizumab in NSCLC as

  • Single agent therapy for recurrence or metastasis if PD-L1 expression-positive (≥50%) as 
     
    • First-line therapy for tumors that are EGFR, ALK, ROS1, and BRAF negative or unknown
    • Subsequent therapy for sensitizing EGFR mutation-positive tumors and prior erlotinib, afatinib, gefitinib, or osimertinib therapy
    • Subsequent therapy for ALK rearrangement-positive tumors and prior crizotinib, ceritinib, or alectinib therapy 
    • Subsequent therapy for ROS1 rearrangement-positive tumors and prior crizotinib therapy.

  • A preferred single agent (if systemic immune checkpoint inhibitors not already given) as subsequent therapy for metastatic NSCLC in patients with performance status 0-2 and tumors with PD-L1 expression levels ≥1%:
     
    • Following progression on a first-line cytotoxic regimen
    • For further progression on other systemic therapy. 
       
  • In combination with pemetrexed and either carboplatin or cisplatin (if pembrolizumab not previously given, nonsquamous cell histology), or in combination with carboplatin and paclitaxel (squamous cell histology) for recurrent or metastatic disease in persons with performance status 0-1 as
     
    • first-line therapy for tumors that are EGFR, ALK, ROS1, BRAF negative or unknown, and PD-L1 less than 50% or unknown; or
    • first-line or subsequent therapy for BRAF V600E-mutation positive tumors; or
    • subsequent therapy for sensitizing EGFR mutation-positive tumors and prior erlotinib, afatinib, gefitinib, or osimertinib therapy; or
    • subsequent therapy for ALK rearrangement-positive tumors and prior crizotinib, ceritinib, alectinib, or brigatinib therapy; or
    • subsequent therapy for ROS1 rearrangement-positive tumors and prior crizotinib or ceritinib therapy; or
    • subsequent therapy for PD-L1 expression-positive (greater than or equal to 50%) tumors and EGFR, ALK, ROS1, and BRAF negative or unknown.
       
  • For continuation maintenance therapy
     
    • in combination with pemetrexed if given first line as part of a pembrolizumab/pemetrexed and either cisplatin or carboplatin regimen for recurrent or metastatic disease and tumors of nonsquamous cell histology, in patients with performance status 0-2, who achieve tumor response or stable disease following initial cytotoxic therapy
    • as a single agent if given first line as part of a pembrolizumab/carboplatin/paclitaxel regimen for recurrent or metastatic disease and tumors of squamous cell histology, in patients with performance status 0-2 who achieve tumor response or stable disease following initial cytotoxic therapy.

Colorectal Cancer

The FDA approved pembrolizumab for the treatment of adult and pediatric patients with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair deficient colorectal cancer that has progressed following treatment with a fluoropyrimidine, oxaliplatin, and irinotecan. This indication was approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

The NCCN Drug and Biologics Compendium (2018) recommends pembrolizumab for colorectal adenocarcinoma

  • Primary treatment as a single agent for unresectable metachronous metastases (defective mismatch repair/high microsatellite instability [dMMR/MSI-H] only) and previous adjuvant FOLFOX (fluorouracil, leucovorin, and oxaliplatin) or CapeOX (capecitabine and oxaliplatin) within the past 12 months
  • Initial therapy as a single agent for patients with unresectable advanced or metastatic disease (defective mismatch repair/high microsatellite instability [dMMR/MSI-H] only) who are not appropriate for intensive therapy
  • Subsequent therapy as a single agent (if nivolumab or pembrolizumab not previously given) for unresectable advanced or metastatic disease (defective mismatch repair/high microsatellite instability [dMMR/MSI-H] only) following previous oxaliplatin- irinotecan- and/or fluoropyrimidine-based therapy.

The NCCN clinical practice guideline on "Colon cancer" (NCCN, 2017) states that "small bowel and appendiceal adenocarcinoma may be treated with systemic chemotherapy according to the NCCN Colon Cancer Guidelines."

Hodgkin's Lymphoma

Kroemer and Galluzzi (2015) noted that the blockade of immunological checkpoints has been studied for the treatment of various solid neoplasms including melanoma, mesothelioma, non-small cell lung carcinoma, and renal cell carcinoma.  A recent study indicated that the vast majority of patients with advanced, heavily pretreated Hodgkin's lymphoma (HL) also respond to a monoclonal antibody targeting programmed cell death 1 (PDCD1, best known as PD-1).  Thus, checkpoint blockers may soon become part of the therapeutic armamentarium against hematological tumors.  The authors anticipated that the realm of immunotherapy will eventually conquer vast portions of the territory that now belongs to hematological malignancies.

The NCCN Drugs and Biologics Compendium (2018) recommend the use of pembrolizumab as a single agent in classical Hodgkin lymphoma as

  • Subsequent systemic therapy as a single agent for refractory disease or for those who have relapsed after 3 or more prior lines of therapy.
  • Palliative therapy as a single agent for refractory disease or for those who have relapsed after 3 or more prior lines of therapy.

The FDA approved pembrolizumab for adults and children with classical Hodgkin lymphoma who are refractory to treatment or who have relapsed after three or more prior lines of therapy (Merck, 2017). The product labeling states that this indication was approved under accelerated approval based on tumor response rate and durability of response. The labeling states that continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

The accelerated FDA approval was based on data in 210 patients with relapsed or refractory classical Hodgkin lymphoma who were enrolled in the multicenter, nonrandomized, open-label KEYNOTE-087 study (Merck, 2017). Patients with active, non-infectious pneumonitis, an allogeneic hematopoietic stem cell transplant (HSCT) within the past five years (or greater than five years but with symptoms of graft-verus-host disease (GVHD)), active autoimmune disease, a medical condition that required immunosuppression, or an active infection requiring systemic therapy were ineligible for the trial. Patients received pembrolizumab at a dose of 200 mg every three weeks until unacceptable toxicity or documented disease progression, or for up to 24 months in patients who did not progress. The major efficacy outcome measures (overall response rate (ORR), complete remission rate (CRR), and duration of response) were assessed by blinded independent central review according to the 2007 revised International Working Group (IWG) criteria. Fifty-eight percent (58%) of patients were refractory to the last prior therapy, including 35 percent with primary refractory disease and 14 percent whose disease was chemorefractory to all prior regimens. Additionally, 61 percent of patients had undergone prior auto-HSCT, 17 percent had no prior brentuximab use, and 36 percent had prior radiation therapy. The median follow-up time was 9.4 months. Efficacy analysis showed an ORR of 69 percent (95% CI: 62, 75), which included a CRR of 22 percent and a partial remission rate (PRR) of 47 percent. Median duration of response among the 145 responders was 11.1 months (range, 0+ to 11.1).

Pembrolizumab was discontinued due to adverse reactions in five percent of 210 patients with classical Hodgkin lymphoma and treatment was interrupted due to adverse reactions in 26 percent of patients (Merck, 2017). Fifteen percent (15%) of patients had an adverse reaction requiring systemic corticosteroid therapy. Serious adverse reactions occurred in 16 percent of patients. The most frequent serious adverse reactions (≥1%) included pneumonia, pneumonitis, pyrexia, dyspnea, GVHD, and herpes zoster. Two patients died from causes other than disease progression; one from GVHD after subsequent allogeneic HSCT and one from septic shock. The most common adverse reactions (occurring in ≥20% of patients) were fatigue (26%), pyrexia (24%), cough (24%), musculoskeletal pain (21%), diarrhea (20%), and rash (20%).

Immune-mediated complications, including fatal events, occurred in patients with classical Hodgkin lymphoma who underwent allogeneic hematopoietic stem cell transplantation (HSCT) after being treated with pembrolizumab. (Merck, 2017) The labeling recommends to follow patients closely for early evidence of transplant-related complications, and intervene promptly.

Data on pediatric patients are limited and efficacy was extrapolated from the results in the adult trial (Merck, 2017).

In refractory or relapsed classical Hodgkin lymphoma, pembrolizumab is approved for use in adult patients at a fixed dose of 200 mg and in pediatric patients at a dose of 2 mg/kg (up to a maximum of 200 mg). Pembrolizumab is administered intravenously every three weeks until disease progression or unacceptable toxicity, or up to 24 months in patients without disease progression.

Urothelial Carcinoma (Transitional Cell Carcinoma)

On May 23, 2017, the FDA approved pembrolizumab for the treatment of patients with locally advanced or metastatic urothelial carcinoma who are ineligible for cisplatin-containing chemotherapy. This indication is approved under accelerated approval based on tumor response rate and duration of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

In the second-line setting, pembrolizumab is approved for the treatment of patients with locally advanced or metastatic urothelial carcinoma who have disease progression during or following platinum-containing chemotherapy or within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy.

Subsequently, in June 2018, the FDA added PD-L1 status into the label by stating pembrolizumab is indicated for the treatment of patients with locally advanced or metastatic urothelial carcinoma who are not eligible for cisplatin-containing chemotherapy and whose tumors express PD-L1 [Combined Positive Score (CPS) ≥10], or in patients who are not eligible for any platinum-containing chemotherapy regardless of PD-L1 status. The FDA decision was based on an assessment conducted by a data monitoring committee (DMC) for the phase III KEYNOTE-361 study. The DMC identified that patients with PD-L1–low status had decreased overall survival in the single-agent immunotherapy arms compared with chemotherapy.

Pembrolizumab is approved for use in these indications at a fixed dose of 200 mg every three weeks until disease progression or unacceptable toxicity, or up to 24 months in patients without disease progression.

The first-line approval was based on data from a multicenter, open-label, single-arm trial, KEYNOTE-052, investigating pembrolizumab in 370 patients with locally advanced or metastatic urothelial carcinoma who were not eligible for cisplatin-containing chemotherapy. Patients with autoimmune disease or medical conditions that required systemic corticosteroids or other immunosuppressive medication were excluded from the trial. Patients received pembrolizumab at a dose of 200 mg every three weeks until unacceptable toxicity or disease progression; patients without disease progression could be treated for up to 24 months. The major efficacy outcome measures were objective response rate (ORR), according to the Response Evaluation Criteria In Solid Tumors (RECIST) 1.1, as assessed by independent radiology review, and duration of response.

The efficacy analysis showed an ORR of 29 percent (95% CI: 24, 34), with a complete response rate of 7 percent and a partial response rate of 22 percent. The median duration of response had not been reached (range: 1.4+ to 17.8+ months) at the time of FDA approval. The median follow-up time was 7.8 months.

In KEYNOTE-052, pembrolizumab was discontinued due to adverse reactions in 11 percent of patients. The most common adverse reactions (in ≥ 20% of patients) were fatigue (38%), musculoskeletal pain (24%), decreased appetite (22%), constipation (21%), rash (21%) and diarrhea (20%). Eighteen patients (5%) died from causes other than disease progression. Five patients (1.4%) who were treated with pembrolizumab experienced sepsis which led to death, and three patients (0.8%) experienced pneumonia which led to death. Adverse reactions leading to interruption of pembrolizumab occurred in 22 percent of patients; the most common (≥1%) were liver enzyme increase, diarrhea, urinary tract infection, acute kidney injury, fatigue, joint pain, and pneumonia. Serious adverse reactions occurred in 42 percent of patients, the most frequent (≥2%) of which were urinary tract infection, hematuria, acute kidney injury, pneumonia, and urosepsis.

The second-line approval was based on data from a multicenter, randomized, active-controlled trial, KEYNOTE-045, investigating pembrolizumab in patients with locally advanced or metastatic urothelial carcinoma with disease progression on or after platinum-containing chemotherapy. Patients with autoimmune disease or a medical condition that required immunosuppression were excluded from the trial. Patients were randomized to receive either pembrolizumab 200 mg every three weeks (n=270) or investigator’s choice of any of the following chemotherapy regimens, all given intravenously, every three weeks (n=272): paclitaxel 175 mg/m2 (n=84), docetaxel 75 mg/m2 (n=84), or vinflunine 320 mg/m2 (n=87). Treatment continued until unacceptable toxicity or disease progression; patients without disease progression could be treated for up to 24 months. The major efficacy outcomes were overall survival (OS) and progression-free survival (PFS), as assessed by a blinded independent central review (BICR) per RECIST 1.1; additional efficacy outcome measures were ORR, as assessed by BICR per RECIST 1.1, and duration of response.

Pembrolizumab demonstrated superior OS compared to chemotherapy. Findings demonstrated that pembrolizumab resulted in a 27 percent reduction in the risk of death compared to chemotherapy – with 155 events (57%) observed in the pembrolizumab arm, compared to 179 events (66%) in the chemotherapy arm (HR, 0.73 [95% CI: 0.59, 0.91], p=0.004); the median OS was 10.3 months (95% CI: 8.0, 11.8) in the pembrolizumab arm, compared to 7.4 months (95% CI: 6.1, 8.3) in the chemotherapy arm. In October 2016, the study was stopped early at the recommendation of an independent Data Monitoring Committee following an interim analysis that showed pembrolizumab met the superiority thresholds for OS in the overall study population.

There was no statistically significant difference between pembrolizumab and chemotherapy with respect to progression-free survival (PFS). There were 218 events (81%) observed in the pembrolizumab arm, compared to 219 events (81%) in the chemotherapy arm (HR, 0.98 [95% CI: 0.81, 1.19], p=0.833). The median PFS was 2.1 months (95% CI: 2.0, 2.2) in the pembrolizumab arm, compared to 3.3 months (95% CI: 2.3, 3.5) in the chemotherapy arm.

Analysis of the ORR endpoint showed a statistically significant improvement with pembrolizumab, as compared to chemotherapy. The ORR was 21 percent (95% CI: 16, 27) in the pembrolizumab arm (with a complete response rate of 7 percent and a partial response rate of 14 percent), compared to 11 percent (95% CI: 8, 16) in the chemotherapy arm (with a complete response rate of 3 percent and a partial response rate of 8 percent) (p=0.002). At the time of FDA approval, the median duration of response for patients treated with pembrolizumab had not yet been reached (range: 1.6+ to 15.6+ months), compared to 4.3 months (range: 1.4+ to 15.4+ months) in the chemotherapy arm. The median follow-up time for this trial was 9.0 months.

In KEYNOTE-045, pembrolizumab was discontinued due to adverse reactions in eight percent of patients. The most common adverse reaction resulting in permanent discontinuation of pembrolizumab was pneumonitis (1.9%). Adverse reactions leading to interruption of pembrolizumab occurred in 20 percent of patients; the most common (≥1%) were urinary tract infection (1.5%), diarrhea (1.5%), and colitis (1.1%). The most common adverse reactions (≥20%) in patients who received pembrolizumab versus those who received chemotherapy were fatigue (38% vs 56%), musculoskeletal pain (32% vs 27%), pruritus (23% vs 6%), decreased appetite (21% vs 21%), nausea (21% vs 29%) and rash (20% vs 13%). Serious adverse reactions occurred in 39 percent of pembrolizumab-treated patients, the most frequent (≥2%) of which were urinary tract infection, pneumonia, anemia, and pneumonitis.

KEYNOTE-361 (NCT02853305) is an ongoing, multicenter, randomized study in previously untreated patients with metastatic urothelial carcinoma who are eligible for platinum-containing chemotherapy. The study compares KEYTRUDA with or without platinum-based chemotherapy (i.e., cisplatin or carboplatin with gemcitabine) to platinum-based chemotherapy alone. The trial also enrolled a third arm of monotherapy with KEYTRUDA to compare to platinum-based chemotherapy alone. The independent Data Monitoring Committee (iDMC) for the study conducted a review of early data and found that in patients classified as having low PD-L1 expression (CPS <10), those treated with KEYTRUDA monotherapy had decreased survival compared to those who received platinum-based chemotherapy. The iDMC recommended to stop further accrual of patients with low PD-L1 expression in the monotherapy arm, however, no other changes were recommended, including any change of therapy for patients who had already been randomized to and were receiving treatment in the monotherapy arm. 

The NCCN Drugs and Biologics Compendium (2018) has the following recommendations for pembrolizumab in urothelial carcinoma:

  • Bladder cancer - Used first-line as a single agent in cisplatin ineligible patients whose tumors express PD-L1 or who are not eligible for any platinum-containing chemotherapy regardless of PD-L1 expression, as subsequent systemic therapy post-platinum as a single agent, or for metastatic disease as subsequent systemic therapy
  • Primary Carcinoma of the Urethra - Used as a single agent for first-line therapy in cisplatin ineligible patients whose tumors express PD-L1 or who are not eligible for any platinum-containing chemotherapy regardless of PD-L1 expression, as a single agent as subsequent systemic therapy for recurrent or metastatic disease. Chemotherapy regimen based on histology
  • Upper GU Tract Tumors - Used as a single agent as first-line systemic therapy in cisplatin ineligible patients whose tumors express PD-L1 or who are not eligible for any platinum-containing chemotherapy regardless of PD-L1 expression, and as subsequent systemic therapy post-platinum for metastatic disease
  • Urothelial Carcinoma of the Prostate - Used as a single agent as first-line systemic therapy in cisplatin ineligible patients whose tumors express PD-L1 or who are not eligible for any platinum-containing chemotherapy regardless of PD-L1 expression, and as subsequent systemic therapy post-platinum for metastatic disease.

Microsatellite Instability-High (MSI-H) or Mismatch Repair Deficient (dMMR) Solid Tumors

The U.S. Food and Drug Administration granted accelerated approval of pembrolizumab for the treatment of adult and pediatric patients with unresectable or metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) solid tumors (Merck, 2017). This indication covers patients with solid tumors that have progressed following prior treatment and who have no satisfactory alternative treatment options.

MSI-H and dMMR tumors contain abnormalities that affect the proper repair of DNA inside the cell (Merck, 2017). Tumors with these biomarkers are most commonly found in colorectal, endometrial and gastrointestinal cancers, but also less commonly appear in cancers arising in the breast, prostate, bladder, thyroid gland and other places. Approximately 5 percent of patients with metastatic colorectal cancer have MSI-H or dMMR tumors.

Pembrolizumab was approved for this indication using the Accelerated Approval pathway, under which the FDA may approve drugs for serious conditions where there is unmet medical need and a drug is shown to have certain effects that are reasonably likely to predict a clinical benefit to patients (Merck, 2017). The FDA has stated that further study is required to verify and describe anticipated clinical benefits of pembrolizumab, and the manufacturer is currently conducting these studies in additional patients with MSI-H or dMMR tumors.

The safety and efficacy of pembrolizumab for this indication were studied in patients with MSI-H or dMMR solid tumors enrolled in one of five uncontrolled, single-arm clinical trials (Merck, 2017). In some trials, patients were required to have MSI-H or dMMR cancers, while in other trials, a subgroup of patients were identified as having MSI-H or dMMR cancers by testing tumor samples after treatment began. A total of 15 cancer types were identified among 149 patients enrolled across these five clinical trials. The most common cancers were colorectal, endometrial and other gastrointestinal cancers. The review of pembrolizumab for this indication was based on the percentage of patients who experienced complete or partial shrinkage of their tumors (overall response rate) and for how long (durability of response). Of the 149 patients who received pembrolizumab in the trials, 39.6 percent had a complete or partial response. For 78 percent of those patients, the response lasted for six months or more.

The safety and effectiveness of pembrolizumab in pediatric patients with MSI-H central nervous system cancers have not been established (Merck, 2017).

The recommended dose of pembrolizumab in adults with MSI-H or dMMR solid tumors is 200 mg administered as an intravenous infusion over 30 minutes every three weeks until disease progression, unacceptable toxicity, or up to 24 months in patients without disease progression (Merck, 2017). In children, the recommended dose of pembrolizumab is 2 mg/kg (up to a maximum of 200 mg) administered as an intravenous infusion over 30 minutes every three weeks until disease progression or unacceptable toxicity, or up to 24 months in patients without disease progression.

In a multi-center phase 1 clinical trial, Brahmer et al (2012) administered intravenous anti-PD-L1 antibody (at escalating doses ranging from 0.3 to 10 mg/kg body weight) to patients with selected advanced cancers.  Anti-PD-L1 antibody was administered every 14 days in 6-week cycles for up to 16 cycles or until the patient had a complete response (CR) or confirmed disease progression.  As of February 24, 2012, a total of 207 patients -- 75 with non-small-cell lung cancer (NSCLC)r, 55 with melanoma, 18 with colorectal cancer, 17 with renal-cell cancer, 17 with ovarian cancer, 14 with pancreatic cancer, 7 with gastric cancer, and 4 with breast cancer -- had received anti-PD-L1 antibody.  The median duration of therapy was 12 weeks (range of 2 to 111).  Grade 3 or 4 toxic effects that investigators considered to be related to treatment occurred in 9 % of patients.  Among patients with a response that could be evaluated, an objective response (CR or partial response [PR]) was observed in 9 of 52 patients with melanoma, 2 of 17 with renal-cell cancer, 5 of 49 with NSCLC, and 1 of 17 with ovarian cancer.  Responses lasted for 1 year or more in 8 of 16 patients with at least 1 year of follow-up.  The authors concluded that antibody-mediated blockade of PD-L1 induced durable tumor regression (ORR of 6 to 17 %) and prolonged stabilization of disease (rates of 12 to 41 % at 24 weeks) in patients with advanced cancers, including NSCLC, melanoma, and renal-cell cancer.

Mesothelioma

An UpToDate review on “Systemic treatment for unresectable malignant pleural mesothelioma” (Tsao and Vogelzang, 2015) states that “Immunotherapy using checkpoint inhibitors may offer a more promising direction for disease control.  In a preliminary report, treatment of 25 mesothelioma patients (88 % with previous systemic therapy) with the anti-PD1 antibody pembrolizumab resulted in 6 partial responses and 13 patients with stable disease, for an overall disease control rate of 76 %.  All responding patients remained on therapy at the time of analysis.  Additional clinical studies with pembrolizumab are being initiated”.  The study cited was an abstract from the American Association of Cancer Research 2015 meeting.  Also, an UpToDate review on “Malignant peritoneal mesothelioma: Treatment” (Alexander and Kindler, 2015) does not mention pembrolizumab as a therapeutic option.

Furthermore, the NCCN Drugs & Biologics Compendium (2018) does list malignant pleural mesothelioma as a recommended indication of pembrolizumab as subsequent single-agent therapy.

Central Nervous System Tumors

Blumenthal and colleagues (2016) noted that patients with progressive primary brain tumors (PBT) are attracted to promising new treatments, even prior to convincing data. Anti-PD1 immunotherapies have been in the spotlight since publication of ground-breaking results for metastatic melanoma with pembrolizumab.  These investigators reported on the response and toxicity of pembrolizumab in patients with advanced PBT.  They retrospectively reviewed the charts of 22 patients (17 adults and 5 children) with recurrent central nervous system (CNS) tumors treated with pembrolizumab.  The authors analyzed prior antineoplastic therapies, steroid usage, and outcomes.  Patients received a median of 2 neoplastic therapies prior to pembrolizumab, and a median of 3 infusions of pembrolizumab in adults and 4 in children; 12 patients (9 adults and 3 children) started pembrolizumab on steroids (median dose in adults 4 mg; range of 2 to 8, and in children 1.5 mg, range of 0.5 to 4) and 5 patients received steroids later during pembrolizumab treatment.  A total of 12 patients (10 adults and 2 children) received concomitant bevacizumab with pembrolizumab; side effects were minimal.  All patients showed progressive tumor growth during therapy.  Median OS from the start of pembrolizumab was 2.6 months in adults and 3.2 months in children; 2 glioblastoma patients underwent tumor resection following treatment with pembrolizumab.  Tumor-lymphocytic response in these cases was unremarkable, and PD-L1 immuno-staining was negative.  The authors concluded that in this series of 22 patients with recurrent primary brain tumors, pembrolizumab showed no clinical or histologic effectiveness.  These investigators do not recommend further use of pembrolizumab for recurrent PBT unless convincing prospective clinical trial data are published.

Also, the NCCN Drugs & Biologics Compendium (2018) does not list central nervous system tumor/glioblastoma as a recommended indication of pembrolizumab; however it does list single agent treatment with pembrolizumb for brain metastases in patients with melanoma or non-small cell lung cancer as a recommended indication.

The NCCN clinical practice guideline on “Central nervous system cancers” (Version 1.2018) does mention pembrolizumab as a therapeutic option for brain metastases in patients with melanoma or non-small cell lung cancer.  Furthermore, NCCN’s Drugs & Biologics Compendium (2018) does not list astrocytoma as a recommended indication of pembrolizumab.

Chronic Lymphocytic Leukemia

The NCCN Guidelines on Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (v.2.2019) gives a 2B recommendation for the use of pembrolizumab as a single agent or in combination with ibrutinib for treatment of histologic (Richter's) transformation to diffuse large B-cell lymphoma (clonally related or unknown clonal status) for patients with del(17p)/TP53 mutation or who are chemotherapy refractory and unable to receive chemoimmunotherapy.

Ding et al (2017) stated chronic lymphocytic leukemia (CLL) patients progressed early on ibrutinib often develop Richter transformation (RT) with a short survival of about 4 months. Preclinical studies suggest that programmed death 1 (PD-1) pathway is critical to inhibit immune surveillance in CLL. This phase 2 study was designed to test the efficacy and safety of pembrolizumab, a humanized PD-1-blocking antibody, at a dose of 200 mg every 3 weeks in relapsed and transformed CLL. Twenty-five patients including 16 relapsed CLL and 9 RT (all proven diffuse large cell lymphoma) patients were enrolled, and 60% received prior ibrutinib. Objective responses were observed in 4 out of 9 RT patients (44%) and in 0 out of 16 CLL patients (0%). All responses were observed in RT patients who had progression after prior therapy with ibrutinib. After a median follow-up time of 11 months, the median overall survival in the RT cohort was 10.7 months, but was not reached in RT patients who progressed after prior ibrutinib. Treatment-related grade 3 or above adverse events were reported in 15 (60%) patients and were manageable. Analyses of pretreatment tumor specimens from available patients revealed increased expression of PD-ligand 1 (PD-L1) and a trend of increased expression in PD-1 in the tumor microenvironment in patients who had confirmed responses. Overall, pembrolizumab exhibited selective efficacy in CLL patients with RT. The results of this study are the first to demonstrate the benefit of PD-1 blockade in CLL patients with RT, and could change the landscape of therapy for RT patients if further validated.

An UpToDate review on “Overview of the treatment of chronic lymphocytic leukemia” (Rai and Stilgenbauer, 2016) does not mention pembrolizumab as a therapeutic option.

Head and Neck Cancers

Gentzler et al (2016) stated that immune checkpoint inhibitors have been identified as breakthrough treatment in melanoma given its dramatic response to PD-1/PD-L1 blockade. This is likely to extend to many other cancers as hundreds of clinical trials are being conducted or proposed using this exciting modality of therapy in a variety of malignancies.  While immune checkpoint inhibitors have been extensively studied in melanoma and more recently in lung cancer, little is known regarding immune checkpoint blockade in other cancers.  The authors focused on the tumor immune microenvironment, the expression of PD-1/PD-L1 and the effect of immune modulation using PD-1 or PD-L1 inhibitors in patients with head and neck, prostate, urothelial, renal, breast, gastro-intestinal and lung cancers.

In an open-label, multi-center, phase Ib trial, Seiwert et al (2016) examined the effects of pembrolizumab in patients with recurrent or metastatic HNSCC. Patients were eligible for enrolment if they were aged 18 years or older, had a confirmed diagnosis of recurrent or metastatic HNSCC, and had any level of PD-L1 expression (i.e., at least 1 % of tumor cells or stroma that were PD-L1-positive by immunohistochemistry).  Patients received pembrolizumab 10 mg/kg intravenously every 2 weeks.  Primary outcomes were safety in the per-protocol population and the proportion of patients with centrally reviewed overall response per Response Evaluation Criteria In Solid Tumors (RECIST, version 1.1).  Overall response was analyzed in the full analysis set, which was defined as all patients who had received at least 1 dose of pembrolizumab, had measurable disease at baseline, and 1 post-baseline scan or patients without a post-baseline scan who discontinued therapy because of disease progression or a drug-related adverse event.  Of the 104 patients screened between June 7, 2013, and October 3, 2013, 81 (78 %) were PD-L1-positive.  Of these, 60 patients with PD-L1-positive HNSCC were enrolled and treated: 23 (38 %) were HPV-positive and 37 (62 %) were HPV-negative.  Pembrolizumab was well-tolerated, with 10 (17 %) of 60 patients having grade 3 to 4 drug-related adverse events, the most common of which were increases in alanine aminotransferase and in aspartate aminotransferase, and hyponatremia, each occurring in 2 of 60 patients; 1 patient developed a grade 3 drug-related rash. 27 (45 %) of 60 patients experienced a serious adverse event.  There were no drug-related deaths.  The proportion of patients with an overall response by central imaging review was 18 % (8 of 45 patients; 95 % CI: 8 to 32) in all patients and was 25 % (4 of 16 patients; 7 to 52) in HPV-positive patients and 14 % (4 of 29 patients; 4 to 32) in HPV-negative patients.  The authors concluded that pembrolizumab was well-tolerated and demonstrated clinically meaningful anti-tumor activity in recurrent or metastatic HNSCC, supporting further study of pembrolizumab as anti-cancer therapy for advanced head and neck cancers.

On August 5, 2016, the FDA granted accelerated approval to pembrolizumab for the treatment of patients with recurrent or metastatic HNSCC with disease progression on or after platinum-containing chemotherapy. The approval was based on demonstration of a durable ORR in a subgroup of patients in an international, multi-center, non-randomized, open-label, multi-cohort study.  This subgroup included 174 patients with recurrent or metastatic HNSCC who had disease progression on or after platinum-containing chemotherapy.  Patients received intravenous pembrolizumab 10 mg/kg every 2 weeks or 200 mg every 3 weeks; ORR was determined by an independent review committee according to (RECIST 1.1.  The ORR for these 174 patients was 16 % (95 % CI: 11 to 22).  The median response duration had not been reached at the time of analysis.  The range for duration of response was 2.4 months to 27.7 months (response ongoing).  Among the 28 responding patients, 23 (82 %) had responses of 6 months or longer. Safety data was evaluated in 192 patients with HNSCC receiving at least 1 dose of pembrolizumab 10 mg/kg every 2 weeks or 200 mg every 3 weeks.  The most common (greater than or equal to 20 %) AEs were fatigue, decreased appetite, and dyspnea.  Adverse events occurring in patients with HNSCC were similar to those occurring in patients with melanoma or NSCLC, with the exception of an increased incidence of facial edema (10 % all grades, 2.1 % grades 3 to 4) and new or worsening hypothyroidism (14.6 % all grades).  The most frequent (greater than or equal to 2 %) serious AEs were pneumonia, dyspnea, confusional state, vomiting, pleural effusion, and respiratory failure.  Clinically significant immune-mediated AEs included pneumonitis, colitis, hepatitis, adrenal insufficiency, diabetes mellitus, skin toxicity, myositis, and thyroid disorders.

As a condition of the accelerated approval, Merck is required to conduct a multi-center, randomized trial establishing the superiority of pembrolizumab over standard therapy to verify and describe the clinical benefit of pembrolizumab. Merck has an ongoing multicenter, randomized trial (KEYNOTE 040) in patients with recurrent or met HNSCC with disease progression on or after platinum-containing chemotherapy with a primary end-point of OS.  The recommended dose and schedule of pembrolizumab for this indication is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks (Food and Drug Administration, 2016).

The NCCN Drugs and Biologics Compendium (2019) recommends pembrolizumab for very advanced and recurrent/persistent head and neck squamous cell carcinoma with mixed subtypes as a single agent for non-nasopharyngeal cancer as a first-line therapy option (cateogry 2B) for PD-L1 positive recurrent, unresectable or metastatic tumors; or as a second-line therapy (Cateogry 1) if disease progression on or after platinum-containing chemotherapy; or for previously treated PD-L1 positive recurrent or metastatic nasopharyngeal cancer (Category 2B) in

  • Newly diagnosed T4b, any N, M0 disease, unresectable nodal disease with no metastases, or for patients who are unfit for surgery and performance status (PS) 3
  • Metastatic (M1) disease at initial presentation or recurrent/persistent disease with distant metastases, or unresectable locoregional recurrence or second primary with prior radiation therapy (RT) and PS 0-2
  • Unresectable locoregional recurrence without prior RT and PS 3. 

Merkel Cell Carcinoma

Winkler et al (2016) reported the use of an anti-PD-1 antibody for treatment of a patient with metastatic MCC. An 80-yearold patient with metastatic MCC received off-label treatment with the anti-PD-1 antibody pembrolizumab after the disease had progressed during therapy with oral etoposide.  A PET-CT scan performed after 3 cycles of pembrolizumab revealed response to therapy with reduced size of the adrenal gland metastases and less PET activity in the adrenal gland and lymph node metastases.  Further on, treatment was resumed due to disease progression in a treatment-free interval of more than 4 months.  During subsequent months of treatment size of the metastases stabilized and uptake of nuclide by all tumor sites once again decreased.  The authors concluded that these results revealed the potential effectiveness of an anti-PD-1 antibody for treatment of metastatic MCC.  They thus contribute to currently limited data on use of anti-PD-1 antibodies for treatment of MCC.  This is, moreover, the 1st report of successful resumption of treatment of metastatic MCC with an anti-PD-1 antibody.  Moreover, they stated that results from ongoing trials will contribute to determination of the relevance of PD-1 blockade in metastatic MCC.

Nghiem et al (2016) stated that MCC is an aggressive skin cancer that is linked to exposure to ultraviolet light and the Merkel-cell polyomavirus (MCPyV). Advanced MCC often responds to chemotherapy, but responses are transient.  Blocking the programmed death 1 (PD-1) immune inhibitory pathway is of interest, because these tumors often express PD-L1, and MCPyV-specific T cells express PD-1.  In this multi-center, phase II, non-controlled study, these researchers assigned adults with advanced MCC who had received no previous systemic therapy to receive pembrolizumab (anti-PD-1) at a dose of 2 mg/kg of body weight every 3 weeks.  The primary end-point was the objective response rate according to RECIST, version 1.1.  Efficacy was correlated with tumor viral status, as assessed by serologic and immune-histochemical testing.  A total of 26 patients received at least 1 dose of pembrolizumab.  The objective response rate among the 25 patients with at least 1 evaluation during treatment was 56 % (95 % confidence interval [CI]: 35 to 76); 4 patients had a complete response, and 10 had a partial response.  With a median follow-up of 33 weeks (range of 7 to 53), relapses occurred in 2 of the 14 patients who had had a response (14 %).  The response duration ranged from at least 2.2 months to at least 9.7 months.  The rate of progression-free survival (PFS) at 6 months was 67 % (95 % CI: 49 to 86).  A total of 17 of the 26 patients (65 %) had virus-positive tumors.  The response rate was 62 % among patients with MCPyV-positive tumors (10 of 16 patients) and 44 % among those with virus-negative tumors (4 of 9 patients).  Drug-related grade 3 or 4 adverse events occurred in 15 % of the patients.  The authors concluded that in this study, 1st-line therapy with pembrolizumab in patients with advanced MCC was associated with an objective response rate of 56 %.  Responses were observed in patients with virus-positive tumors and those with virus-negative tumors.  Also, the authors stated that “As of now, none of the predictive tests are sufficiently robust to be used in clinical decision making regarding whether to use or not to use PD-1 blockers in Merkel-cell carcinoma”.  Additional investigation with longer follow-up and larger patient cohorts are needed to ascertain the effectiveness of pembrolizumab for the treatment of Merkel-cell carcinoma.

In a phase II single-arm study, the PD-1 checkpoint inhibitor pembrolizumab effectively shrank tumors and prolonged survival in more than 50 %of patients with MCC. Responses were significantly more durable than those typically seen with chemotherapy (No authors listed, 2016).

An UpToDate review on “Staging and treatment of Merkel cell carcinoma” (Tai, 2016) states that “Adjuvant immunotherapy -- Checkpoint inhibitor immunotherapy is showing some promise in patients with metastatic MCC, but there are no data on its use in an adjuvant setting. However, pembrolizumab has demonstrated some activity in the metastatic disease setting.  Another promising checkpoint inhibitor is nivolumab”.

The NCCN Drugs & Biologics Compendium (2019) indicates pembrolizumab for Merkel cell carcinoma for distant metastatic disease or disseminated recurrence with or without surgery or radiation therapy(Category 2A) and also states pembrolizumab may be considered as a treatment option for patients with recurrent locally advanced disesase (Category 2A).

Anal Cancer

The NCCN Drugs and Biologics Compendium (2018) recommends pembrolizumab for anal squamous cell carcinoma as second-line therapy as a single agent for metastatic disease [2A].

Penile Cancer

Also, the NCCN Drugs & Biologics Compendium (2018) does list penile cancer as a recommended indication of pembrolizumab in select patients as a single agent as subsequent-line systemic therapy if unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) tumor that has progressed following prior treatment and no satisfactory alternative treatment options.

Breast Cancer

The NCCN Drugs & Biologics Compendium (2018) Drugs & Biologics Compendium (2018) does not list breast cancer as a recommended indication of pembrolizumab.

Hepatobiliary Cancers

On November 9 2018, the U.S. Food and Drug Administration approved pembrolizumab (Keytruda) fot the treatment of patients with hepatocellular carcinoma (HCC) who have been previously treated with sorafenib (Nexavar). This approval was based on data from the KEYNOTE-224 study (Zhu et al 2018), a single-arm trial in patients with HCC who had disease progression on or after sorafenib or were intolerant to sorafenib; had measurable disease; and had Child-Pugh class A liver impairment. 

Zhu et al 2018 (KEYNOTE-224; NCT02702414) stated immune checkpoint blockade therapy has shown promising results in patients with advanced hepatocellular carcinoma. The authors aimed to assess the efficacy and safety of pembrolizumab in this patient population. KEYNOTE-224 is a non-randomised, multicentre, open-label, phase 2 trial that is set in 47 medical centres and hospitals across ten countries. Eligible patients had pathologically confirmed hepatocellular carcinoma; had previously been treated with sorafenib and were either intolerant to this treatment or showed radiographic progression of their disease after treatment; an Eastern Cooperative Oncology Group performance status of 0-1; adequate organ function, and were Child-Pugh class A. Participants received 200 mg pembrolizumab intravenously every 3 weeks for about 2 years or until disease progression, unacceptable toxicity, patient withdrawal, or investigator decision. The primary endpoint was objective response, defined as the proportion of patients with complete or partial response in all patients who received at least one dose of pembrolizumab, which was radiologically confirmed by use of the Response Evaluation Criteria in Solid Tumors version 1.1 by central review. Safety was also assessed in all treated patients. This trial is ongoing but closed to enrollment. Between June 7, 2016, and Feb 9, 2017, 169 patients with advanced hepatocellular carcinoma were screened, of whom 104 eligible patients were enrolled and treated. As of data cutoff on Feb 13, 2018, 17 (16%) patients were still receiving pembrolizumab. The authors recorded an objective response in 18 (17%; 95% CI 11-26) of 104 patients. The best overall responses were one (1%) complete and 17 (16%) partial responses; meanwhile, 46 (44%) patients had stable disease, 34 (33%) had progressive disease, and six (6%) patients who did not have a post-baseline assessment on the cutoff date were considered not to be assessable. Treatment-related adverse events occurred in 76 (73%) of 104 patients, which were serious in 16 (15%) patients. Grade 3 treatment-related events were reported in 25 (24%) of the 104 patients; the most common were increased aspartate aminotransferase concentration in seven (7%) patients, increased alanine aminotransferase concentration in four (4%) patients, and fatigue in four (4%) patients. One (1%) grade 4 treatment-related event of hyperbilirubinaemia occurred. One death associated with ulcerative oesophagitis was attributed to treatment. Immune-mediated hepatitis occurred in three (3%) patients, but there were no reported cases of viral flares. The authors concluded that pembrolizumab was effective and tolerable in patients with advanced hepatocellular carcinoma who had previously been treated with sorafenib. These results indicate that pembrolizumab might be a treatment option for these patients. This drug is undergoing further assessment in two phase 3, randomised trials as a second-line treatment in patients with hepatocellular carcinoma.

Ma et al (2018) stated the remarkable clinical activity of PD-1 antibody in advanced hepatocellular carcinoma (HCC) highlights the importance of PD-1/PD-L1-mediated immune escape as therapeutic target in HCC. However, the frequency and prognostic significance of PD-Ls genetic alterations in HCC remain unknown. Methods: Fluorescence in situ hybridization were used to determine PD-Ls genetic alterations, and qPCR data coupled with immunofluorescence were used to measure the mRNA and protein levels of PD-Ls. Clinical relevance and prognostic value of 9p24.1 genetic alterations were investigated on tissue microarray containing three independent cohorts of 578 HCC patients. The results were further validated in an independent cohort of 442 HCC patients from The Cancer Genome Atlas (TCGA) database. In total, 7.1%-15.0% for amplification and 15.8%-31.3% for polysomy of 9p24.1 were revealed in three cohorts of HCC patients, similar to the objective response rate of PD-1 antibody in HCC. Patients with 9p24.1 genetic alterations significantly and independently correlated with unfavorable outcomes than those without. FISH and qPCR data coupled with immunofluorescence revealed that genetic alterations of 9p24.1 robustly contributed to PD-L1 and PD-L2 upregulation. In addition, increased expression of PD-L1 instead of PD-L2 also predicted poor survival by multivariate analyses. Meanwhile, high infiltration of PD-1+ immune cells also indicated dismal survival in HCC. The authors concluded that amplification or higher expression of PD-L1 significantly and independently correlated with unfavorable survival in HCC patients, authenticating the PD-1/PD-L1 axis as rational immunotherapeutic targets for HCC.

Finn et al 2017 (KEYNOTE-240; NCT0270240) states there are no approved therapies for patients with hepatocellular carcinoma (HCC) after disease progression on sorafenib, or for patients with intolerance to sorafenib. HCC often arises in the background of chronic inflammation and is also associated with an immunosuppressed microenvironment, providing a strong rationale to evaluate immunotherapy in HCC. The randomized, double-blind, placebo-controlled phase 3 KEYNOTE-240 was designed to compare the efficacy and safety of the anti–PD-1 antibody pembrolizumab + best supportive care (BSC) vs placebo + BSC in patients with previously treated advanced HCC. Methods: Eligibility criteria include age ≥18 years, confirmed diagnosis of Barcelona Clinic Liver Cancer (BCLC) stage C disease or BCLC stage B disease not amenable to or refractory to locoregional therapy, disease not amenable to a curative treatment approach (e.g., transplantation, surgery, or ablation), documented progression after treatment with sorafenib or intolerance to sorafenib, Child-Pugh liver score A, and ECOG performance status 0-1. ~408 patients will be randomly assigned 2:1 to receive pembrolizumab 200 mg IV every 3 weeks (Q3W) + BSC or placebo Q3W + BSC for up to 35 cycles or until disease progression, unacceptable toxicity, patient withdrawal of consent, or investigator decision. Randomization will be stratified by geographic region, macrovascular invasion, and α-fetoprotein. BSC will be provided by the investigator per local treatment practices. Response will be assessed every 6 weeks per RECIST v1.1 by central imaging vendor review. Adverse events (AEs) will be assessed throughout treatment and for 30 days thereafter (90 days for serious AEs) and graded per NCI CTCAE v4.0. Primary objectives are comparison of progression-free survival per RECIST v1.1 by central imaging vendor review and overall survival between treatment arms. Secondary objectives are comparison of objective response rate, duration of response, disease control rate, and time to progression per RECIST v1.1 by central imaging vendor review, and evaluation of safety and tolerability. Enrollment in KEYNOTE-240 is ongoing.

National Comprehensive Cancer Network’s clinical practice guideline on “Hepatobiliary cancers” (Version 3.2018) states there are limited clinical trial data to support pembrolizumab in this setting and cites Sicklick et al (2017) who stated precision medicine has been studied in patients with advanced, heavily-treated cancers by administering molecularly matched monotherapies. With increasing availability of large gene assays and cognate agents, the authors hypothesized that offering customized combination therapies to treatment-naïve tumors would be feasible and improve response rates. The Investigation of Profile-Related Evidence Determining Individualized Cancer Therapy (I-PREDICT, NCT02534675) targeted metastatic and/or unresectable, untreated lethal cancers ( > 50% 2-yr mortality). Comprehensive genomic profiling (CGP, Foundation Medicine; 315 genes), and, if possible, PD-(L)1 IHC, tumor mutational burden (TMB) and circulating tumor DNA were performed. A molecular tumor board discussed results immediately upon receipt, and emphasized customized combinations. Final decisions were the treating physician’s choice. CGP was evaluable in 40/47 treatment-naïve pts (85.1%); 22 (46.8%) were treated [17 matched (36.2%); 5 unmatched (10.6%); 11 different diagnoses). The other 25 pts (53.2%) are awaiting therapy (8, 17%) or could not be treated (17, 36.2%), mainly due to patient deterioration or payor limitations. Each tumor had a unique genomic portfolio. The median (range) of genomic alterations/patient was 5 (1-12). TMB was available in 17 pts (12 low; 4 intermediate; 1 high). The median (range) Matching Score [(matches (#)/characterized genomic alterations (#)] was 33% (14-100%; 100% designated immunotherapy match or all alterations matched to targeted agents) [Reference PMID 2719717]. Nine/17 matched pts (53%) achieved SD > 6 months (N = 2) or CR (1)/PR (6). The median progression-free survival (PFS) for matched vs. unmatched pts was 4.7 vs. 1.0 months (P= 0.0019). There were no drug-related deaths. The authors concluded that with the use of broad-based DNA sequencing assays, inclusion of pts earlier in their disease course, timely mandated molecular tumor board discussions, and increasing availability of cognate drugs for customized combinations, the authors report: 1) high molecular matching rates (~36%); 2) high rates of SD > 6 months/CR/PR (~53%); and 3) improved PFS. Study expansion is ongoing.

Furthermore, the NCCN Drugs & Biologics Compendium (2018) mentions pembrolizumab as a therapeutic option for hepatocellular cancer, gallbladder cancer, intrahepatic cholangiocarcinoma, and extrahepatic cholangiocarcinoma).

Mycosis Fungoides/Sezary Syndrome

The NCCN Drugs & Biologics Compendium (2018) list Primary Cutaneous Lymphomas- mycosis fungoides (MF)/Sezary syndrome (SS), and Primary Cutaneous CD30+ T-Cell Lymphoproliferative Disorders as recommended indications of pembrolizumab.

Gastric Cancer

On September 22, 2017, The U.S. Food and Drug Administration (FDA) granted accelerated approval of Keytruda (pembrolizumab) for the treatment of persons with recurrent locally advanced or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma whose tumors express PD-L1  [Combined Positive Score (CPS) ≥1] as determined by an FDA-approved test, with disease progression on or after two or more prior lines of therapy including fluoropyrimidine- and platinum-containing chemotherapy and if appropriate, HER2/neu-targeted therapy. This indication is approved under accelerated approval based on tumor response rate and durability of response. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials (FDA, 2017).

The accelerated approval for Keytruda was based on results from the KEYNOTE 059 (NCT02335411) study,  a global, multicenter, non-randomized, non-comparative, open-label, multi-cohort trial , in which 259 individuals were enrolled with gastric or GEJ adenocarcinoma that progressed on at least two prior systemic treatments for advanced disease. Among the 259 patients, 55 percent (n=143, median age 64 years) had tumors that expressed PD-L1 with a CPS ≥1, and microsatellite stable (MSS) tumor status or undetermined microsatellite instability (MSI) or mismatch repair (MMR) status. Previous treatment must have included a fluoropyrimidine and platinum doublet. HER2/neu-positive patients must have previously received treatment with approved HER2/neu-targeted therapy. Patients with active autoimmune disease or a medical condition that required immunosuppression or with clinical evidence of ascites by physical exam were ineligible. Patients received Keytruda at a dose of 200 mg every 3 weeks until unacceptable toxicity or disease progression that was symptomatic, rapidly progressive, required urgent intervention, occurred with a decline in performance status, or was confirmed at least 4 weeks later with repeat imaging. Patients without disease progression were treated for up to 24 months. Assessment of tumor status was performed every six to nine weeks. The major efficacy outcome measures were objective response rate (ORR) according to the Response Evaluation Criteria In Solid Tumors (RECIST) 1.1, as assessed by blinded independent central review, and duration of response (FDA, 2017).

For the 143 patients with tumors expressing PD-L1 and who were either MSS or had unknown MSI or dMMR status, the objective response rate was 13.3% (95% CI: 8.2, 20.0); 1.4% had complete responses and 11.9% had partial responses. Among the 19 responding patients, the response duration ranged from 2.8+ to 19.4+ months, with 11 patients (58%) having response durations of 6 months or longer and 5 patients (26%) having response durations of 12 months or longer (FDA, 2017).

Among the 259 patients, 7 (3%) had tumors that were determined to be MSI-High. An objective response was observed in 4 patients, including 1 complete response. The duration of response ranged from 5.3+ to 14.1+ months (FDA, 2017)

Adverse reactions occurring in patients with gastric cancer were similar to those occurring in patients with melanoma or non-small cell lung cancer (NSCLC). The most common adverse reactions for Keytruda (pembrolizumab) (reported in ≥20% of patients) were fatigue, musculoskeletal pain, decreased appetite, pruritis, diarrhea, nausea, rash, pyrexia, cough, dyspnea, and constipation (FDA, 2017).

The NCCN Drugs & Biologics Compendium (2018) list palliative therapy for gastric adenocarcinoma as recommended indications of pembrolizumab (2A Recommendation).

Salivary Tumors

The NCCN Drugs & Biologics Compendium (2018) does not list salivary tumor as a recommended indication of pembrolizumab.

Bone Cancers

George et al (2017) stated that response to immune checkpoint blockade in mesenchymal tumors is poorly characterized, but immunogenomic dissection of these cancers could inform immunotherapy mediators.  These researchers identified a treatment-naive patient who has metastatic uterine leiomyosarcoma and has experienced complete tumor remission for greater than 2 years on programmed cell death protein 1 (PD-1) (pembrolizumab) monotherapy.  They analyzed the primary tumor, the sole treatment-resistant metastasis, and germline tissue to explore mechanisms of immunotherapy sensitivity and resistance.  Both tumors stained diffusely for PD-L2 and showed sparse PD-L1 staining.  PD-1+ cell infiltration significantly decreased in the resistant tumor (p = 0.039).  Genomically, the treatment-resistant tumor uniquely harbored bi-allelic PTEN loss and had reduced expression of two neo-antigens that demonstrated strong immuno-reactivity with patient T cells in-vitro, suggesting long-lasting immunological memory.  In this near-complete response to PD-1 blockade in a mesenchymal tumor, the authors identified PTEN mutations and reduced expression of genes encoding neo-antigens as potential mediators of resistance to immune checkpoint therapy.

In an open-label, multi-center,  phase II clinical trial, Toulmonde et al (2017) evaluated the safety and effectiveness of PD-1 targeting in combination with metronomic chemotherapy in sarcomas.  This study consisted of 4 cohorts of patients with advanced soft-tissue sarcoma (STS), including leiomyosarcoma (LMS), undifferentiated pleomorphic sarcoma (UPS), other sarcomas (others), and gastro-intestinal stromal tumor (GIST).  All patients received 50-mg twice-daily cyclophosphamide 1 week on and 1 week off, and 200-mg of intravenous pembrolizumab every 3 weeks.  There was a dual primary end-point, encompassing both the non-progression and objective responses at 6 months per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 for LMS, UPS, and others and 6-month non-progression for GIST.  An objective response rate of 20 % and/or a 6-month non-progression rate of 60 % were determined as reasonable objectives for treatment with meaningful effect.  Correlative studies of immune biomarkers were planned from patient tumor and plasma samples.  Between June 2015 and July 2016, a total of 57 patients were included (median [range] age of 59.5 [18.5 to 84.0] years; 24 women [42 %]); 50 patients were assessable for the efficacy end-point; 3 patients experienced tumor shrinkage, resulting in a partial response (PR) in a single solitary fibrous tumor.  The 6-month non-progression rates were 0 %, 0 %, 14.3 % (95 % CI: 1.8 % to 42.8 %) for LMS, UPS, and others, respectively, and 11.1 % (95 % CI: 2.8 % to 48.3 %) for GIST.  The most frequent adverse events (AEs) were grade 1 or 2 fatigue, diarrhea, and anemia.  The only patient who experienced PR was the only one with strong PD-1 ligand 1-positive staining in immune cell.  Strong infiltration by macrophage expressing the inhibitory enzyme indoleamine 2,3-dioxygenase 1 (IDO1) was observed in the majority of cases.  Moreover, a significant increase in the kynurenine to tryptophan ratio was observed in patient plasma samples during the study treatment.  The authors found that PD-1 inhibition has limited activity in selected STS and GIST.  This may be explained by an immunosuppressive tumor microenvironment resulting from macrophage infiltration and IDO1 pathway activation.

Le et al (2017) stated the genomes of cancers deficient in mismatch repair contain exceptionally high numbers of somatic mutations. In a proof-of-concept study, the authors previously showed that colorectal cancers with mismatch repair deficiency were sensitive to immune checkpoint blockade with antibodies to programmed death receptor-1 (PD-1). The authors expanded this study to evaluate the efficacy of PD-1 blockade in patients with advanced mismatch repair-deficient cancers across 12 different tumor types. Objective radiographic responses were observed in 53% of patients, and complete responses were achieved in 21% of patients. Responses were durable, with median progression-free survival and overall survival still not reached. Functional analysis in a responding patient demonstrated rapid in vivo expansion of neoantigen-specific T cell clones that were reactive to mutant neopeptides found in the tumor. These data support the hypothesis that the large proportion of mutant neoantigens in mismatch repair-deficient cancers make them sensitive to immune checkpoint blockade, regardless of the cancers' tissue of origin.

Tawbi et al (2017) stated patients with advanced sarcomas have a poor prognosis and few treatment options that improve overall survival. Chemotherapy and targeted therapies offer short-lived disease control. The authors assessed pembrolizumab, an anti-PD-1 antibody, for safety and activity in patients with advanced soft-tissue sarcoma or bone sarcoma. In this two-cohort, single-arm, open-label, phase 2 study, The authors enrolled patients with soft-tissue sarcoma or bone sarcoma from 12 academic centres in the USA that were members of the Sarcoma Alliance for Research through Collaboration (SARC). Patients with soft-tissue sarcoma had to be aged 18 years or older to enroll; patients with bone sarcoma could enroll if they were aged 12 years or older. Patients had histological evidence of metastatic or surgically unresectable locally advanced sarcoma, had received up to three previous lines of systemic anticancer therapy, had at least one measurable lesion according to the Response Evaluation Criteria In Solid Tumors version 1.1, and had at least one lesion accessible for biopsy. All patients were treated with 200 mg intravenous pembrolizumab every 3 weeks. The primary endpoint was investigator-assessed objective response. Patients who received at least one dose of pembrolizumab were included in the safety analysis and patients who progressed or reached at least one scan assessment were included in the activity analysis. Accrual is ongoing in some disease cohorts. Between March 13, 2015, and Feb 18, 2016, 86 patients were enrolled, 84 of whom received pembrolizumab (42 in each disease cohort) and 80 of whom were evaluable for response (40 in each disease cohort). Median follow-up was 17·8 months (IQR 12·3-19·3). Seven (18%) of 40 patients with soft-tissue sarcoma had an objective response, including four (40%) often patients with undifferentiated pleomorphic sarcoma, two (20%) of ten patients with liposarcoma, and one (10%) of ten patients with synovial sarcoma. No patients with leiomyosarcoma (n=10) had an objective response. Two (5%) of 40 patients with bone sarcoma had an objective response, including one (5%) of 22 patients with osteosarcoma and one (20%) of five patients with chondrosarcoma. None of the 13 patients with Ewing's sarcoma had an objective response. The most frequent grade 3 or worse adverse events were anemia (six [14%]), decreased lymphocyte count (five [12%]), prolonged activated partial thromboplastin time (four [10%]), and decreased platelet count (three [7%]) in the bone sarcoma group, and anemia, decreased lymphocyte count, and prolonged activated partial thromboplastin time in the soft-tissue sarcoma group (three [7%] each). Nine (11%) patients (five [12%] in the bone sarcoma group and four [10%] in the soft-tissue sarcoma group) had treatment-emergent serious adverse events (SAEs), five of whom had immune-related SAEs, including two with adrenal insufficiency, two with pneumonitis, and one with nephritis. The authors concluded that the primary endpoint of overall response was not met for either cohort. However, pembrolizumab showed encouraging activity in patients with undifferentiated pleomorphic sarcoma or dedifferentiated liposarcoma. Enrolment to expanded cohorts of those subtypes is ongoing to confirm and characterise the activity of pembrolizumab.

Furthermore, the NCCN Drugs & Biologics Compendium (2018) does recommend this treatment for patients with MSI-H/dMMR chondrosarcomas, Ewing sarcomas, and osteosarcomas. NCCN does not recommend this treatment for giant cell tumor of bone or chordomas due to limited evidence for the presence of MSI in this tumor type.

Primary Mediastinal Large B-cell Lymphoma (PMBCL)

On June 13, 2018, the Food and Drug Administration granted accelerated approval to pembrolizumab (Keytruda, Merck) for the treatment of adult and pediatric patients with refractory primary mediastinal large B-cell lymphoma (PMBCL), or who have relapsed after two or more prior lines of therapy. The efficacy of pembrolizumab was investigated in 53 patients with relapsed or refractory PMBCL enrolled in a multicenter, open-label, single-arm trial (Study KEYNOTE-170; NCT02576990). Patients were not eligible if they had active non-infectious pneumonitis, allogeneic HSCT within the past 5 years (or greater than 5 years but with symptoms of GVHD), active autoimmune disease, a medical condition that required immunosuppression, or an active infection requiring systemic therapy. The patients were treated with pembrolizumab 200 mg intravenously every 3 weeks until unacceptable toxicity or documented disease progression, or for up to 24 months for patients who did not progress. Disease assessments were performed every 12 weeks and assessed by blinded independent central review according to the 2007 revised IWG criteria. 

Among the 53 patients accrued, the baseline characteristics were: median age 33 years (range: 20 to 61 years), 43% male; 92% White; 43% had an ECOG performance status (PS) of 0 and 57% had an ECOG PS of 1. The median number of prior lines of therapy administered for the treatment of PMBCL was 3 (range 2 to 8). Thirty-six percent had primary refractory disease, 49% had relapsed disease refractory to the last prior therapy, and 15% had untreated relapse. Twenty-six percent of patients had undergone prior autologous HSCT, and 32% of patients had prior radiation therapy. All patients had received rituximab as part of a prior line of therapy.

An overall response rate (ORR) was seen in 45% of patients (95% CI: 32, 60); complete response was seen in 11% of patients; and partial response in 34% of patients.  For the 24 responders, the median time to first objective response (complete or partial response) was 2.8 months (range 2.1 to 8.5 months).

The NCCN Drugs & Biologics Compendium (2018) lists relapsed or refractory diffuse large B-cell lymphoma-primary mediastinal large B-cell lymphoma as recommended indications of pembrolizumab (2A Recommendation).

Cervical Cancer

On June 12, 2018, the Food and Drug Administration approved pembrolizumab for patients with recurrent or metastatic cervical cancer with disease progression on or after chemotherapy whose tumors express PD-L1 (CPS ≥1) as determined by an FDA-approved test. The FDA also concurrently approved PD-L1 IHC 22C3 pharmDx (Dako North America Inc.) as a companion diagnostic.

Pembrolizumab was investigated in 98 patients with recurrent or metastatic cervical cancer enrolled in a single cohort (Cohort E) in Study KEYNOTE-158 (NCT02628067), a multicenter, non-randomized, open-label, multi-cohort trial. The trial excluded patients with autoimmune disease or a medical condition that required immunosuppression. Patients were treated with pembrolizumab intravenously at a dose of 200 mg every 3 weeks until unacceptable toxicity or documented disease progression. Patients with initial radiographic disease progression could receive additional doses of treatment during confirmation of progression unless disease progression was symptomatic, was rapidly progressive, required urgent intervention, or occurred with a decline in performance status. Patients without disease progression could be treated for up to 24 months. Assessment of tumor status was performed every 9 weeks for the first 12 months, and every 12 weeks thereafter. The major efficacy outcome measures were ORR according to RECIST 1.1, as assessed by blinded independent central review, and duration of response.

Among the 98 patients in Cohort E, 77 (79%) had tumors that expressed PD-L1 with a CPS ≥ 1 and received at least one line of chemotherapy in the metastatic setting. PD-L1 status was determined using the PD-L1 IHC 22C3 pharmDx Kit. The baseline characteristics of these 77 patients were: median age was 45 years (range: 27 to 75 years); 81% were White, 14% Asian, 3% Black; ECOG PS was 0 (32%) or 1 (68%); 92% had squamous cell carcinoma, 6% adenocarcinoma, and 1% adenosquamous histology; 95% had M1 disease and 5% had recurrent disease; 35% had one and 65% had two or more prior lines of therapy in the recurrent or metastatic setting. No responses were observed in patients whose tumors did not have PD-L1 expression (CPS ˂1).

Of the 77 patients with measurable endpoints, objective response rates were seen in 14.3% (95% CI: 7.4, 24.1). Complete response was seen in 2.6% and partial response was seen in 11.7% of patients. A response duration greater than or equal to 6 months was seen in 91% of patients.

The NCCN Drugs & Biologics Compendium (2018) lists pembrolizumab as preferred second-line therapy as a single agent for recurrent or metastatic cervical cancer (adenocarcinoma, squamous cell carcionma) (2A Recommendation).

Prostate Cancer

Hansen et al (2018) stated patients with castration-resistant prostate cancer derive only modest clinical benefit from available therapies. Blockade of the inhibitory programmed death 1 (PD-1) receptor by monoclonal antibodies has been effective in several malignancies. Results from the prostate adenocarcinoma cohort of the nonrandomized phase Ib KEYNOTE-028 trial of pembrolizumab in advanced solid tumors are presented. Key eligibility criteria included advanced prostate adenocarcinoma, unsuccessful standard therapy, measurable disease per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST v1.1), and PD-1 ligand (PD-L1) expression in ≥1% of tumor or stromal cells. Patients received pembrolizumab 10 mg/kg every 2 weeks until disease progression or intolerable toxicity for up to 24 months. Primary end point was objective response rate (ORR) per RECIST v1.1 by investigator review. The median patient age in this cohort (n = 23) was 65 years; 73.9% of patients received at least two prior therapies for metastatic disease. There were four confirmed partial responses, for an ORR of 17.4% [95% confidence interval (CI) 5.0%-38.8%]; 8 of 23 (34.8%) patients had stable disease. Median duration of response was 13.5 months. Median progression-free survival (PFS) and overall survival (OS) were 3.5 and 7.9 months, respectively; 6-month PFS and OS rates were 34.8% and 73.4%, respectively. One patient remained on treatment at data cutoff. After a median follow-up of 7.9 months, 14 (60.9%) patients experienced treatment-related adverse events (TRAEs), most commonly nausea (n = 3, 13.0%). Four (17.3%) experienced grade 3/4 TRAEs: grade 3 peripheral neuropathy, grade 3 asthenia, grade 3 fatigue, and grade 4 lipase increase. No pembrolizumab-related deaths or discontinuations occurred. The authors concluded that pembrolizumab resulted in durable objective response in a subset of patients with heavily pretreated, advanced PD-L1-positive prostate cancer, and its side effect profile was favorable.

The NCCN Drugs & Biologics Compendium (2018) lists castration-resistant distant metastatic (M1) prostate cancer that is microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) as recommended indications of pembrolizumab (2B Recommendation).

Vulvar Cancer

Shields and Gordinier (2018) stated advanced vulvar cancer is associated with a very poor prognosis. Surgical resection is the mainstay of treatment, with radiation indicated for areas at high risk for recurrence. When surgical and radiation options have been exhausted, the effectiveness of systemic chemotherapy is poor. No biologic or targeted agents have been approved for the management of advanced or recurrent vulvar cancer. Pembrolizumab, a humanized monoclonal antibody against programmed death 1 (PD-1), has been successfully used as a target of tumor immune therapy in small cell lung cancer and melanoma. The authors present the first case in the literature of a patient with recurrent vulvar cancer who was treated successfully with pembrolizumab. Caris next-generation testing revealed a PD-L1 and PD-1 mutation (PD-L1 positive, 2+, 100%). She attained a complete clinical remission after 2 cycles, and a CT scan after 6 cycles revealed a significant response by RECIST criteria. After completing 10 cycles, treatment was stopped due to complications of severe malnutrition related to narcotic abuse. A CT scan 10 weeks after the final treatment revealed no adenopathy. The authors concluded that pembrolizumab is a safe and effective chemotherapeutic agent to treat recurrent vulvar carcinoma.

The NCCN Drugs & Biologics Compendium (2018) lists vulvar cancer that is microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR), or if tumors express PD-L1 as recommended indications of pembrolizumab (2A Recommendation).

Neuroendocrine and Adrenal Tumors

The NCCN Drugs & Biologics Compendium (2019) lists pembrolizumab as a therapy option for the management of mismatch repair deficient (dMMR) or microsatellite instability-high (MSI-H) unresectable/metastatic adrenocortical tumors that have progressed following prior treatment and have no satisfactory alternative treatment options (2A) and states pembrolizumab may be considered as treatment for patients for poorly differentiated (high grade)/large or small cell neuroendocrine tumors with mismatch repair-deficient (dMMR) or microsatellite instability-high (MSI-H) tumors that have progressed following prior treatment with no satisfactory alternative treatment options.

Renal Cell Carcinoma (RCC)

On April 19, 2019, the Food and Drug Administration approved pembrolizumab plus axitinib (Inlyta) for the first-line treatment of patients with advanced renal cell carcinoma (RCC). The efficacy of pembrolizumab in combination with axitinib was investigated in KEYNOTE-426 (NCT02853331), a randomized, multicenter, open-label trial conducted in 861 patients who had not received systemic therapy for advanced RCC (Rini 2019). Patients were enrolled regardless of PD-L1 tumor expression status. Patients with active autoimmune disease requiring systemic immunosuppression within the last 2 years were ineligible. Randomization was stratified by International Metastatic RCC Database Consortium (IMDC) risk categories (favorable versus intermediate versus poor) and geographic region (North America versus Western Europe versus “Rest of the World”).

Rini et al (2019) stated the combination of pembrolizumab and axitinib showed antitumor activity in a phase 1b trial (Atkins 2018) involving patients with previously untreated advanced renal-cell carcinoma. Whether pembrolizumab plus axitinib would result in better outcomes than sunitinib in such patients was unclear. In an open-label, phase 3 trial, 861 patients with previously untreated advanced clear-cell renal-cell carcinoma were randomly assigned to receive pembrolizumab (200 mg) intravenously once every 3 weeks for up to 24 months plus axitinib (5 mg) orally twice daily (432 patients) or sunitinib (50 mg) orally once daily for the first 4 weeks of each 6-week cycle (429 patients). Patients who tolerated axitinib 5 mg twice daily for 2 consecutive cycles (6 weeks) could increase to 7 mg and then subsequently to 10 mg twice daily. Axitinib could be interrupted or reduced to 3 mg twice daily and subsequently to 2 mg twice daily to manage toxicity. Treatment with pembrolizumab and axitinib continued until RECIST v1.1-defined progression of disease or unacceptable toxicity. Administration of pembrolizumab and axitinib was permitted beyond RECIST-defined disease progression if the patient was clinically stable and considered to be deriving clinical benefit by the investigator. Assessment of tumor status was performed at baseline, after randomization at Week 12, then every 6 weeks thereafter until Week 54, and then every 12 weeks thereafter. The study population characteristics were: median age of 62 years (range: 26 to 90); 38% age 65 or older; 73% male; 79% White and 16% Asian; 19% and 80% of patients had a baseline KPS of 70 to 80 and 90 to 100, respectively; and patient distribution by IMDC risk categories was 31% favorable, 56% intermediate and 13% poor. The primary end points were overall survival (OS) and progression-free survival (PFS) in the intention-to-treat population. The key secondary end point was the objective response rate (ORR). All reported results are from the protocol-specified first interim analysis. After a median follow-up of 12.8 months, the estimated percentage of patients who were alive at 12 months (OS) was 89.9% in the pembrolizumab–axitinib group and 78.3% in the sunitinib group (hazard ratio for death, 0.53; 95% confidence interval [CI], 0.38 to 0.74; P<0.0001). Median PFS was 15.1 months in the pembrolizumab–axitinib group and 11.1 months in the sunitinib group (hazard ratio for disease progression or death, 0.69; 95% CI, 0.57 to 0.84; P<0.001). The objective response rate (ORR) was 59.3% (95% CI, 54.5 to 63.9) in the pembrolizumab–axitinib group and 35.7% (95% CI, 31.1 to 40.4) in the sunitinib group (P<0.001). The benefit of pembrolizumab plus axitinib was observed across the International Metastatic Renal Cell Carcinoma Database Consortium risk groups (i.e., favorable, intermediate, and poor risk) and regardless of programmed death ligand 1 expression. Grade 3 or higher adverse events of any cause occurred in 75.8% of patients in the pembrolizumab–axitinib group and in 70.6% in the sunitinib group. The authors concluded that among patients with previously untreated advanced renal-cell carcinoma, treatment with pembrolizumab plus axitinib resulted in significantly longer overall survival and progression-free survival, as well as a higher objective response rate, than treatment with sunitinib.

Atkins et al (2018; NCT02853331) stated previous studies combining PD-1 checkpoint inhibitors with tyrosine kinase inhibitors of the VEGF pathway have been characterized by excess toxicity, precluding further development. The authors hypothesized that axitinib, a more selective VEGF inhibitor than others previously tested, could be combined safely with pembrolizumab (anti-PD-1) and yield antitumor activity in patients with treatment-naive advanced renal cell carcinoma. In this ongoing, open-label, phase 1b study, which was done at ten centers in the USA, patients aged 18 years or older who had advanced renal cell carcinoma (predominantly clear cell subtype) with their primary tumor resected, and at least one measureable lesion, Eastern Cooperative Oncology Group performance status 0-1, controlled hypertension, and no previous systemic therapy for renal cell carcinoma were enrolled. Eligible patients received axitinib plus pembrolizumab in a dose-finding phase to estimate the maximum tolerated dose, and additional patients were enrolled into a dose-expansion phase to further establish safety and determine preliminary efficacy. Axitinib 5 mg was administered orally twice per day with pembrolizumab 2 mg/kg given intravenously every 3 weeks. We assessed safety in all patients who received at least one dose of axitinib or pembrolizumab; antitumor activity was assessed in all patients who received study treatment and had an adequate baseline tumor assessment. The primary endpoint was investigator-assessed dose-limiting toxicity during the first two cycles (6 weeks) to estimate the maximum tolerated dose and recommended phase 2 dose. This study is registered with ClinicalTrials.gov, number NCT02133742.  Between Sept 23, 2014, and March 25, 2015, we enrolled 11 patients with previously untreated advanced renal cell carcinoma to the dose-finding phase and between June 3, 2015, and Oct 13, 2015, we enrolled 41 patients to the dose-expansion phase. All 52 patients were analyzed together. No unexpected toxicities were observed. Three dose-limiting toxicities were reported in the 11 patients treated during the 6-week observation period (dose-finding phase): one patient had a transient ischemic attack and two patients were only able to complete less than 75% of the planned axitinib dose because of treatment-related toxicity. At the data cutoff date (March 31, 2017), 25 (48%) patients were still receiving study treatment. Grade 3 or worse treatment-related adverse events occurred in 34 (65%) patients; the most common included hypertension (n=12 [23%]), diarrhea (n=5 [10%]), fatigue (n=5 [10%]), and increased alanine aminotransferase concentration (n=4 [8%]). The most common potentially immune-related adverse events (probably related to pembrolizumab) included diarrhea (n=15 [29%]), increased alanine aminotransferase concentration (n=9 [17%]) or aspartate aminotransferase concentration (n=7 [13%]), hypothyroidism (n=7 [13%]), and fatigue (n=6 [12%]). 28 (54%) patients had treatment-related serious adverse events. At data cutoff, 38 (73%; 95% CI 59·0-84·4) patients achieved an objective response (complete or partial response). The treatment combination of axitinib plus pembrolizumab is tolerable and shows promising antitumor activity in patients with treatment-naive advanced renal cell carcinoma. Whether or not the combination works better than a sequence of VEGF pathway inhibition followed by an anti-PD-1 therapy awaits the completion of a phase 3 trial comparing axitinib plus pembrolizumab with sunitinib monotherapy.

Appendix

Dosing Information

Pembrolizumab is available as Keytruda in a 50-mg and 100-mg single-use vial as a solution.

The recommended dose of pembrolizumab for NSCLC is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks until disease progression, unacceptable toxicity, or up to 24 months in persons without disease progression. When administering Keytruda in combination with chemotherapy, Keytruda should be administered prior to chemotherapy when given on the same day.

The recommended dose of pembrolizumab for melanoma is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks until disease progression or unacceptable toxicity. The average treatment duration for individuals with advanced melanoma is slightly over 6 months.

The recommended pembrolizumab dose and schedule for the adjuvant treatment of melanoma is 200 mg administered as an IV infusion over 30 minutes every 3 weeks until disease recurrence or unacceptable toxicity, for a maximum of 1 year.

The recommended dose of pembrolizumab for head and neck cancer is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks until disease progression, unacceptable toxicity, or up to 24 months in persons without disease progression. 

The recommended dose of pembrolizumab for classical Hodgkin lymphoma is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks for adults; 2 mg/kg (up to 200 mg) administered as an intravenous infusion over 30 minutes every 3 weeks for pediatrics. Treatment should continue until disease progression, unacceptable toxicity, or up to 24 months in patients without disease progression.

The recommended dose of pembrolizumab for urothelial carcinoma is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks until disease progression or unacceptable toxicity, or up to 24 months in patients without disease progression.

The recommended dose of pembrolizumab for MSI-H cancer is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks for adults; 2 mg/kg (up to 200 mg) administered as an intravenous infusion over 30 minutes every 3 weeks for pediatrics. Treatment should continue until disease progression, unacceptable toxicity, or up to 24 months in patients without disease progression.

The recommended dose of pembrolizumab for recurrent locally advanced or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks until disease progression, unacceptable toxicity, or up to 24 months in patients without disease progression.

The recommended dose of pembrolizumab dose for primary mediastinal large B-cell lymphoma (PMBCL) is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks for adults; 2 mg/kg (up to 200 mg) administered as an intravenous infusion over 30 minutes every 3 weeks for pediatrics. Treatment should continue until disease progression, unacceptable toxicity, or up to 24 months in patients without disease progression.

The recommended dose of pembrolizumab for cervical cancer is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks until disease progression, unacceptable toxicity, or up to 24 months in patients without disease progression.

The recommended dose of pembrolizumab for hepatocellular carcinoma is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks until disease progression, unacceptable toxicity, or up to 24 months in patients without disease progression.

The recommended dose of pembrolizumab for Merkel Cell carcinoma is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks for adults; 2 mg/kg (up to 200 mg) administered as an intravenous infusion over 30 minutes every 3 weeks for pediatrics. Treatment should continue until disease progression or unacceptable toxicity, or up to 24 months in patients without disease progression.

The recommended dose of pembrolizumab for kidney cancer of clear cell histology is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks with axitinib 5 mg orally twice daily until disease progression, unacceptable toxicity, or for pembrolizumab, up to 24 months in patients without disease progression. When axitinib is used in combination with pembrolizumab, dose escalation of axitinib above the initial 5 mg dose may be considered at intervals of six weeks or longer.

 

Table: CPT Codes / HCPCS Codes / ICD-10 Codes
Code Code Description

Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+" :

Other CPT codes related to the CPB:

81210 BRAF (B-Raf proto-oncogene, serine/threonine kinase) (eg, colon cancer, melanoma), gene analysis, V600 variant(s
81235 EGFR ( epidermal growth factor receptor) (eg, non-small cell lung cancer) gene analysis, common variants (eg, exon 19 LREA deletion, L858R, T790M, G719A, G719S, L861Q)
81301 Microsatellite instability analysis (eg, hereditary non-polyposis colorectal cancer, Lynch syndrome) of markers for mismatch repair deficiency
88341 Immunohistochemistry or immunocytochemistry, per specimen; each additional single antibody stain procedure (List separately in addition to code for primary procedure)
88342 Immunohistochemistry or immunocytochemistry, per specimen; initial single antibody stain procedure
88360 Morphometric analysis, tumor immunohistochemistry (eg, Her-2/neu, estrogen receptor/progesterone receptor), quantitative or semiquantitative, per specimen, each single antibody stain procedure; manual
88361     using computer-assisted technology
96413 Chemotherapy administration, IV infusion technique; up to 1 hour, single or initial substance/drug
96414     each additional hour (list in addition to code for primary procedure)

HCPCS codes covered if selection criteria are met:

J9271 Injection, pembrolizumab, 1 mg

Other HCPCS codes related to the CPB:

Dacomitinib - no specific code :

J8565 Gefitinib, oral, 250 mg
J9022 Injection, atezolizumab, 10 mg
J9042 Injection, brentuximab vedotin, 1 mg
J9045 Injection, carboplatin, 50 mg
J9060 Injection, cisplatin, powder or solution, 10 mg
J9228 Injection, ipilimumab, 1 mg
J9263 Injection, oxaliplatin, 0.5 mg
J9264 Injection, paclitaxel protein-bound particles, 1 mg
J9299 Injection, nivolumab, 1 mg
J9305 Injection, pemetrexed, 10 mg

ICD-10 codes covered if selection criteria are met :

C00.0 - C07, C09.0 - C10.9, C12 - C14.8 Malignant neoplasm of lip, oral cavity, and pharynx [except nasopharynx] [not covered for salivary glands]
C15.3 - C15.9 Malignant neoplasm of esophagus [Gastroesophageal junction adenocarcinoma]
C16.0 - C16.9 Malignant neoplasm of stomach
C17.0 - C17.9 Malignant neoplasm of small intestine including duodenum [small bowel adenocarcinoma]
C18.0 - C20 Malignant neoplasm of colon and rectum
C21.0 - C21.8 Malignant neoplasm of anus and anal canal [anal adenocarcinoma]
C22.0 Liver cell carcinoma [hepatocellular carcinoma]
C22.1 Intrahepatic bile duct carcinoma [cholangiocarcinoma]
C23 Malignant neoplasm of gallbladder
C24.0 - C24.9 Malignant neoplasm of other and unspecified parts of biliary tract
C25.0 - C25.9 Malignant neoplasm of pancreas
C26.0 Malignant neoplasm of intestinal tract, part unspecified
C30.0 - C30.1 Malignant neoplasm of nasal cavity and middle ear
C31.0 - C31.9 Malignant neoplasms of accessory sinuses
C32.0 - C32.9 Malignant neoplasm of larynx
C34.00 - C34.92 Malignant neoplasm of bronchus and lung
C40.00 - C41.9 Malignant neoplasm of bone and articular cartilage [osteosarcoma, ewing sarcoma, osteosarcoma]
C43.0 - C43.9 Malignant melanoma of skin
C4A.0 - C4A.9 Merkel cell carcinoma
C44.00, C44.02, C44.09 Unspecified malignant neoplasm, squamous cell carcinoma, or other specified malignant neoplasm of skin of lip
C44.101 - C44.1992 Other and unspecified malignant neoplasm of skin of eyelid including canthus
C44.201 - C44.299 Other and unspecified malignant neoplasm of skin of ear and external auricular canal
C44.300 - C44.399 Other and unspecified malignant neoplasm of skin of other and unspecified parts of face
C44.40 - C44.49 Other and unspecified malignant neoplasm of skin of scalp and neck
C45.0 Mesothelioma of pleura
C48.1 - C48.2 Malignant neoplasm of peritoneum [primary peritoneal cancer]
C49.0 - C49.9 Malignant neoplasm of other connective and soft tissue [soft tissue sarcomas]
C51.0 - C51.9 Malignant neoplasm of vulva
C53.0 - C53.9 Malignant neoplasm of cervix uteri
C54.1 Malignant neoplasm of endometrium
C56.1 - C56.9 Malignant neoplasm of ovary
C57.00 - C57.02 Malignant neoplasm of fallopian tube
C58 Malignant neoplasm of placenta [gestational trophoblastic neoplasia]
C60.1 - C60.9 Malignant neoplasm of penis
C61 Malignant neoplasm of prostate
C62.90 - C62.92 Malignant neoplasm of testis, unspecified whether descended or undescended
C64.1 - C64.9 Malignant neoplasm of kidney, except renal pelvis
C65.0 - C65.9 Malignant neoplasm of renal pelvis
C66.0 - C66.9 Malignant neoplasm of ureter
C67.0 - C67.9 Malignant neoplasm of bladder
C68.0 Malignant neoplasm of urethra
C69.40 - C69.42 Malignant neoplasm of ciliary body [uveal melanoma]
C73 Malignant neoplasm of thyroid gland
C74.00 - C74.92 Malignant neoplasm of adrenal gland
C76.0 Malignant neoplasm of head, face and neck
C78.89 Secondary malignant neoplasm of other digestive organs
C7A.010 - C7A.8 Malignant neuroendocrine tumors
C7B.8 Other secondary neuroendocrine tumors
C81.10 - C81.79 Hodgkin lymphoma
C84.00 - C84.09 Mycosis fungoides [non-Hodgkin's lymphoma]
C84.10 - C84.19 Sezary disease [non-Hodgkin's lymphoma]
C85.20 - C85.29 Mediastinal (thymic) large B-cell lymphoma
C86.0 Extranodal NK/T-cell lymphoma, nasal type
C86.6 Primary cutaneous CD30-positive T-cell proliferations
C91.10 - C91.12 Chronic lymphocytic leukemia of B-cell type [small lymphocytic lymphoma]
D03.0 - D03.9 Melanoma in situ

ICD-10 codes not covered for indications listed in the CPB:

C08.0 - C08.9 Malignant neoplasm of other and unspecified major salivary glands
C22.0 - C22.9 Malignant neoplasm of liver and intrahepatic bile ducts
C45.0 - C45.9 Mesothelioma
C49.0 - C49.A9 Malignant neoplasm of other connective and soft tissue [pleomorphic dermal sarcoma]
C50.011 - C50.929 Malignant neoplasm of breast
C69.50 - C69.52 Malignant neoplasm of lacrimal gland and duct
C71.0 - C71.9 Malignant neoplasm of brain, unspecified [glioblastoma]
C90.00 - C90.02 Multiple myeloma
C92.10 - C92.12 Chronic myeloid leukemia, BCR/ABL-positive

The above policy is based on the following references:

  1. Brahmer JR, Tykodi SS, Chow LQ, et al. Safety and activity of anti-PD-L1 antibody in patients with advanced cancer. N Engl J Med. 2012;366(26):2455-2465.
  2. Tanaka Y, Okamura H. Anti-PD-1 antibody: Basics and clinical application. Gan To Kagaku Ryoho. 2013;40(9):1145-1149.
  3. Tang PA, Heng DY. Programmed death 1 pathway inhibition in metastatic renal cell cancer and prostate cancer. Curr Oncol Rep. 2013;15(2):98-104.
  4. Hamid O, Robert C, Daud A, et al. Safety and tumor responses with lambrolizumab (anti-PD-1) in melanoma. N Engl J Med. 2013;369(2):134-144.
  5. National Cancer Institute (NCI). Melanoma. Cancer Topics. Bethesda, MD: NCI; 2011. Available at: http://www.cancer.gov/cancertopics/types/melanoma. Accessed September 5, 2014.
  6. U.S. Food and Drug Administration (FDA). FDA approves Keytruda for advanced melanoma. FDA News. Silver Spring, MD: FDA; September 4, 2014.
  7. Optum. Keytruda (pembrolizumab): First FDA-approved PD-1 inhibitor for advanced melanoma. Optum Insight HTP Alert. Issue 112. Eden Prarie, MN: Optum; September 2014.
  8. Merck & Co. Inc. Keytruda (pembrolizumab) for injection, for intravenous use. Prescribing Information. Whitehouse Station, NJ: Merck; 2014.   
  9. Langer CJ. Emerging immunotherapies in the treatment of non-small cell lung cancer (NSCLC): The role of immune checkpoint inhibitors. Am J Clin Oncol. 2015;38(4):422-430.
  10. Robert C, Ribas A, Wolchok JD, et al. Anti-programmed-death-receptor-1 treatment with pembrolizumab in ipilimumab-refractory advanced melanoma: A randomised dose-comparison cohort of a phase 1 trial. Lancet. 2014;384(9948):1109-1117.
  11. National Comprehensive Cancer Network (NCCN). Melanoma. NCCN Clinical Practice Guidelines in Oncology, v.1.2015. Fort Washington, PA: NCCN; 2014.
  12. National Comprehensive Cancer Network (NCCN). Central nervous system cancers. NCCN Clinical Practice Guidelines in Oncology, version 1.2015. Fort Washington, PA: NCCN; 2015.
  13. Kroemer G, Galluzzi L. Immunotherapy of hematological cancers: PD-1 blockade for the treatment of Hodgkin's lymphoma. Oncoimmunology. 2015;4(6):e1008853.
  14. National Comprehensive Cancer Network (NCCN). Hodgkin lymphoma. NCCN Clinical Practice Guidelines in Oncology, version 2.2015. Fort Washington, PA: NCCN; 2015.
  15. Tsao AS, Vogelzang N. Systemic treatment for unresectable malignant pleural mesothelioma. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed August 2015.
  16. Alexander HR, Jr., Kindler HL. Malignant peritoneal mesothelioma: Treatment. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed August 2015.
  17. Garon EB, Rizvi NA, Hui R, et al; KEYNOTE-001 Investigators. Pembrolizumab for the treatment of non-small-cell lung cancer. N Engl J Med. 2015;372(21):2018-2028.
  18. Langer CJ. Emerging immunotherapies in the treatment of non-small cell lung cancer (NSCLC): The role of immune checkpoint inhibitors. Am J Clin Oncol. 2015;38(4):422-430
  19. Asmar R, Rizvi NA. Immunotherapy for advanced lung cancer. Cancer J. 2015;21(5):383-391
  20. U.S. Food and Drug Administration (FDA). FDA approves Keytruda for advanced non-small cell lung cancer. Press Release. Silver Spring, MD: FDA; October 2, 2015. 
  21. Sgambato A, Casaluce F, Sacco PC, et al. Anti PD-1 and PDL-1 immunotherapy in the treatment of advanced non-small cell lung cancer (NSCLC): A review on toxicity profile and its management. Curr Drug Saf. 2016;11(1):62-68.
  22. National Comprehensive Cancer Network (NCCN). Pembrolizumab. NCCN Drugs & Biologics Compendium. Fort Washington, PA: NCCN; 2017.
  23. Rai KR, Stilgenbauer S. Overview of the treatment of chronic lymphocytic leukemia. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2016.
  24. Gentzler R, Hall R, Kunk PR, et al. Beyond melanoma: Inhibiting the PD-1/PD-L1 pathway in solid tumors. Immunotherapy. 2016;8(5):583-600.
  25. Seiwert TY, Burtness B, Mehra R, et al. Safety and clinical activity of pembrolizumab for treatment of recurrent or metastatic squamous cell carcinoma of the head and neck (KEYNOTE-012): an open-label, multicentre, phase 1b trial. Lancet Oncol. 2016;17(7):956-965.
  26. Nghiem PT, Bhatia S, Lipson EJ, et al. PD-1 blockade with pembrolizumab in advanced Merkel-cell carcinoma. N Engl J Med. 2016;374(26):2542-2552.
  27. No authors listed. Pembrolizumab yields lasting Merkel cell carcinoma responses. Cancer Discov. 2016;6(6):566.
  28. Tai P. Staging and treatment of Merkel cell carcinoma. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2016.
  29. Nanda R, Chow LQ, Dees EC, et al. Pembrolizumab in patients with advanced triple-negative breast cancer: Phase Ib KEYNOTE-012 Study. J Clin Oncol. 2016;34(21):2460-2467.
  30. Muro K, Chung HC, Shankaran V, et al. Pembrolizumab for patients with PD-L1-positive advanced gastric cancer (KEYNOTE-012): A multicentre, open-label, phase 1b trial. Lancet Oncol. 2016;17(6):717-726.
  31. Pettaway CA. Carcinoma of the penis: Surgical and medical treatment. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2016.
  32. Winkler JK, Bender C, Kratochwil C, et al. PD-1 blockade - a therapeutic option for treatment of metastatic Merkel cell carcinoma. Br J Dermatol. 2017;176(1):216-219.  
  33. Blumenthal DT, Yalon M, Vainer GW, et al. Pembrolizumab: First experience with recurrent primary central nervous system (CNS) tumors. J Neurooncol. 2016;129(3):453-460. 
  34. Armand P, Shipp MA, Ribrag V, et al. Programmed death-1 blockade with pembrolizumab in patients with classical Hodgkin lymphoma after brentuximab vedotin failure. J Clin Oncol. 2016;34(31):3733-3739.
  35. Merck & Co. Inc. Keytruda (pembrolizumab) for injection, for intravenous use. Prescribing Information. uspi-mk3475-iv-1705r011. Whitehouse Station, NJ: Merck; revised May 2017. 
  36. Merck & Co., Inc. FDA approves Merck’s Keytruda (pembrolizumab) for adult and pediatric patients with classical Hodgkin lymphoma (cHL) refractory to treatment, or who have relapsed after three or more prior lines of therapy. News Release. Kenilworth, NJ: Merck; March 14, 2017. 
  37. Merck & Co., Inc. FDA approves Merck’s Keytruda (pembrolizumab) for certain patients with locally advanced or metastatic urothelial carcinoma, a type of bladder cancer. News Release. Kenilworth, NJ: Merck; May 18, 2017.
  38. Merck & Co., Inc. FDA approves Merck’s Keytruda (pembrolizumab) as first-line combination therapy with pemetrexed and carboplatin for patients with metastatic nonsquamous non-small cell lung cancer (NSCLC), irrespective of PD-L1 expression. News Release. Kenilworth, NJ: Merck, May 10, 2017. 
  39. Merck & Co., Inc. FDA approves Merck’s Keytruda (pembrolizumab) for adult and pediatric patients with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair deficient cancer. News Release. Kenilworth, NJ: Merck; May 23, 2017.
  40. U.S. Food and Drug Administration (FDA). Pembrolizumab (Keytruda). Approved Drugs. Silver Spring, MD: FDA; August 5, 2016.
  41. National Comprehensive Cancer Network (NCCN). Hepatobiliary cancers. NCCN Clinical Practice Guidelines in Oncology, Version 3.2017. Fort Washington, PA: NCCN; 2017.
  42. National Comprehensive Cancer Network (NCCN). Pembrolizumab. NCCN Drugs & Biologics Compendium. Fort Washington, PA: NCCN; 2017.
  43. George S, Miao D, Demetri GD, et al. Loss of PTEN is associated with resistance to anti-PD-1 checkpoint blockade therapy in metastatic uterine leiomyosarcoma. Immunity. 2017;46(2):197-204.
  44. Toulmonde M, Penel N, Adam J, et al. Use of PD-1 targeting, macrophage infiltration, and IDO pathway activation in sarcomas: A phase 2 clinical trial. JAMA Oncol. 2018;4(1):93-97. 
  45. U.S. Food and Drug Administration (FDA). FDA grants accelerated approval to pembrolizumab for advanced gastric cancer. FDA News Release. Silver Spring, MD: FDA; September 22, 2017.
  46. Merk & Co., Inc. Keytruda (pembrolizumab) for injection, for intravenous use. Prescribing Information. Reference ID: 4156447. Whitehouse Station, NJ: Merck; revised September 2017.
  47. U.S. Food and Drug Administration (FDA). FDA approves pembrolizumab for treatment of relapsed or refractory PMBCL. FDA News Release. Silver Spring, MD: FDA; June 13, 2018.
  48. U.S. Food and Drug Administration (FDA). FDA approves pembrolizumab for advanced cervical cancer with disease progression during or after chemotherapy. FDA News Release. Silver Spring, MD: FDA; June 12, 2018.
  49. Merck & Co., Inc. Keytruda (pembrolizumab) for injection, for intravenous use. Prescribing Information. Reference ID: 4279266. Whitehouse Station, NJ: Merck; revised June 2018.
  50. Ding W, LaPlant BR, Call TG, et al. Pembrolizumab in patients with CLL and Richter transformation or with relapsed CLL. Blood. 2017;129(26):3419-3427.
  51. Hansen AR, Massard C, Ott PA, et al. Pembrolizumab for advanced prostate adenocarcinoma: findings of the KEYNOTE-028 study. Ann Oncol.2018;29(8):1807-1813.
  52. Shields LBE, Gordinier ME. Pembrolizumab in Recurrent Squamous Cell Carcinoma of the Vulva: Case Report and Review of the Literature. Gynecol Obstet Invest.2018:1-5.
  53. National Comprehensive Cancer Network (NCCN). Pembrolizumab. NCCN Drugs & Biologics Compendium. Fort Washington, PA: NCCN; 2018.
  54. Sicklick JK, Leyland-Jones B, Kato S, et al. Personalized, molecularly matched combination therapies for treatment-naive, lethal malignancies: The I-PREDICT Study. Journal of Clinical Oncology. 2017; 35(15):2512.
  55. Le DT, Durham JN, Smith KN, et al. Mismatch repair deficiency predicts response of solid tumors to PD-1 blockade. Science. 2017;357(6349):409-413.
  56. Tawbi HA, Burgess M, Bolejack V, et al. Pembrolizumab in advanced soft-tissue sarcoma and bone sarcoma (SARC028): A multicentre, two-cohort, single-arm, open-label, phase 2 trial. Lancet Oncol. 2017;18(11):1493-1501.
  57. Merck & Co., Inc. Keytruda (pembrolizumab) for injection, for intravenous use. Prescribing Information. Reference ID: 4365768. Whitehouse Station, NJ: Merck; revised December 2018.
  58. Ma LJ, Feng FL, Dong LQ, et al. Clinical significance of PD-1/PD-Ls gene amplification and overexpression in patients with hepatocellular carcinoma. Theranostics. 2018;8(20):5690-5702.
  59. Zhu AX, Finn RS, Edeline J, et al; KEYNOTE-224 investigators. Pembrolizumab in patients with advanced hepatocellular carcinoma previously treated with sorafenib (KEYNOTE-224): A non-randomised, open-label phase 2 trial. Lancet Oncol. 2018;19(7):940-952.
  60. Finn RS, Chan SL, Zhu AX, et al; KEYNOTE-240 investigators. Randomized phase III study of pembrolizumab versus best supportive care for second-line advanced hepatocellular carcinoma [abstract]. J Clin Oncol. 2017 35:4_suppl, TPS503-TPS503 .
  61. Eggermont AMM, Blank CU, Mandala M, et al. Adjuvant pembrolizumab versus placebo in resected stage III melanoma. N Engl J Med. 2018;378(19):1789-1801.
  62. U.S. Food and Drug Administration (FDA). FDA approves pembrolizumab for adjuvant treatment of melanoma. Approved Drugs. Silver Spring, MD: FDA; February 15, 2019.
  63. National Comprehensive Cancer Network (NCCN). Head and Neck. NCCN Clinical Practice Guidelines in Oncology, version 1.2019. Fort Washington, PA: NCCN; 2019.
  64. Rini BI, Plimack ER, Stus V, et al; KEYNOTE-426 Investigators. Pembrolizumab plus Axitinib versus Sunitinib for Advanced Renal-Cell Carcinoma. N Engl J Med. 2019;380(12):1116-1127.
  65. Atkins MB, Plimack ER, Puzanov I, et al. Axitinib in combination with pembrolizumab in patients with advanced renal cell cancer: a non-randomised, open-label, dose-finding, and dose-expansion phase 1b trial. Lancet Oncol. 2018;19(3):405-415.
  66. U.S. Food and Drug Administration (FDA). Keytruda (pembrolizumab) injection, for intravenous use. Prescribing Information. Reference ID: 4421738. Rockville, MD: FDA; revised April 2019.