Study of Pembrolizumab (MK-3475) in Participants With Advanced Solid Tumors (MK-3475-012/KEYNOTE-012)

This study is being done to investigate the safety, tolerability and anti-tumor activity of pembrolizumab (MK-3475) in participants with advanced triple negative breast cancer (TNBC) (Cohort A), advanced head and neck cancer (Cohorts B and B2), advanced urothelial cancer (Cohort C), or advanced gastric cancer (Cohort D). Additionally, for Cohort D, data is presented for Asian Pacific (AP) participants. Only participants with programmed cell death-ligand 1 (PD-L1) expressing tumors were enrolled in Cohorts A, B, C and D. Participants in Cohort B2 were enrolled irrespective of PD-L1 status.

The primary study hypothesis is that pembrolizumab is safe and well-tolerated.

Eligible participants who completed the first course of up to 35 administrations of pembrolizumab (approximately up to 2 years) for reasons other than disease progression or intolerability, may be eligible for a second course of pembrolizumab for up to approximately 1 additional year at the investigator's discretion. Per protocol, response during this second course will not count towards the efficacy outcome measures and adverse events during this second course will not count towards the safety outcome measures.

Protocol Amendment 01 (08 Aug 2013) included a new study arm (Cohort D) for approximately 32 participants with advanced gastric cancer. Of these 32 participants, 16 will be from sites in the Asia Pacific (AP) region and the other 16 will be from sites outside the AP region.

Protocol Amendment 02 (07 Apr 2014) added a new study arm (Cohort B2) for approximately 110 participants with advanced head and neck cancer who will receive a lower dose of pembrolizumab every three weeks (Q3W). Both programmed cell death ligand 1 (PD-L1)- positive and PD-L1-negative participants will be enrolled into this cohort.

Protocol Amendment 03 (26 May 2015) removed the secondary objective of investigating the relationship between programmed cell death 1 (PD-1) inhibition and up-regulation of cytokines biomarkers predicting response (e.g. Interleukin-10 \[IL-10\]) from the protocol.

Participants who stopped study treatment without progression (e.g. completed 2 years) may have been eligible for up to 1 year of retreatment upon subsequently experiencing disease progression.

With Amendment 05 (11 Dec 2017), once study participants have achieved the study objective or the study has ended, participants will be discontinued from this study and enrolled in an extension study (KEYNOTE-587; NCT03486873) to continue protocol-defined assessments and treatment.

Eligibility Criteria:
Inclusion Criteria:

* Histologically or cytologically-confirmed diagnosis of tumor that is recurrent, metastatic, or persistent:

  * For Cohort A - triple negative breast cancer (estrogen, progesterone, and human epidermal growth factor receptor 2 \[HER2\] negative)
  * For Cohort B - squamous cell carcinoma of the head and neck (including human papilloma virus (HPV)-positive head and neck squamous cell cancer).
  * For Cohort C - urothelial tract cancer of the renal pelvis, ureter, bladder, or urethra (transitional cell or non-transitional cell histology)
  * For Cohort D - adenocarcinoma of the stomach or gastroesophageal junction
  * For Cohort B2 - squamous cell carcinoma of the head and neck (both HPV-positive and -negative head and neck squamous cell cancer)
* Any number of prior treatment regimens
* Measurable disease
* Eastern Cooperative Oncology Group (ECOG) Performance status of 0 or 1
* Female participants of childbearing potential must be willing to use 2 methods of birth control or be surgically sterile, or abstain from heterosexual activity for the course of the study through 120 days after the last dose of study treatment
* Male participants must agree to use an adequate method of contraception starting with the first dose of study therapy through 120 days after the last dose of study treatment

Exclusion Criteria:

* Currently participating in/has participated in a study of an investigational agent or using an investigational device within 4 weeks of the first dose of study treatment
* Diagnosis of immunosuppression or receiving systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of study treatment
* Anti-cancer monoclonal antibody treatment within 4 weeks prior to study Day 1 or not recovered from adverse events due to agents administered more than 4 weeks earlier
* Chemotherapy, targeted small molecule therapy or radiation therapy within 2 weeks prior to study Day 1 or not recovered from adverse events due to a previously administered agent
* Known additional malignancy that is progressing or requires active treatment excepting basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or in situ cervical cancer that has undergone potentially curative therapy
* Known active central nervous system (CNS) metastases and/or carcinomatous meningitis
* Active autoimmune disease requiring systemic treatment within the past 3 months or documented history of clinically severe autoimmune disease, or syndrome that requires systemic steroids or immunosuppressive agents
* Evidence of interstitial lung disease
* Active infection requiring systemic therapy
* Known psychiatric or substance abuse disorders
* Pregnant, breastfeeding, or expecting to conceive or father children within the projected duration of the trial, starting with the pre-screening or screening visit through 120 days after the last dose of trial treatment
* Prior therapy with an anti-programmed cell death 1 (PD-1), anti-PD-L1, anti-PD-L2, anti-CD137 antibody, or anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) antibody
* Known history of human immunodeficiency virus (HIV)
* Known active Hepatitis B or Hepatitis C
* Received live vaccine within 30 days prior to start of study treatment
* Is or has an immediate family member (e.g., spouse, parent/legal guardian, sibling or child) who is Investigational site or Sponsor staff directly involved with this trial, unless prospective Independent Review Board (IRB) approval (by Chair or Designee) is given allowing exception to this criterion for a specific participant