• Progression-Free Survival (PFS) Per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 as Assessed by Blinded Central Imaging [ Time Frame: Through Database Cutoff Date of 20-May-2019 (Up to approximately 31.2 months) ]
  PFS was defined as the time from randomization to the first documented progressive disease (PD) or death due to any cause, whichever occurred first. Per RECIST 1.1, PD was defined as ≥20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of ≥5 mm. Note: The appearance of one or more new lesions was also considered PD. The PFS per RECIST 1.1 is presented.
• Overall Survival (OS) [ Time Frame: Through Database Cutoff Date of 20-May-2019 (Up to approximately 31.2 months) ]
  OS was defined as the time from randomization to death due to any cause. Participants without documented death at the time of the analysis were censored at the date of the last follow-up. The OS is presented.

• Progression-Free Survival (PFS) Per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 as Assessed by Blinded Central Imaging [ Time Frame: Up to 24 months ]
  PFS is defined as the time from randomization to the first documented progressive disease (PD) per RECIST 1.1 based on BICR or death due to any cause, whichever occurs first. Per RECIST 1.1, PD is defined as ≥20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of ≥5 mm. Note: The appearance of one or more new lesions is also considered PD. PFS, as assessed by blinded central imaging, will be presented.
• Overall Survival (OS) [ Time Frame: Up to 24 months ]
  OS is defined as the time from randomization to death due to any cause. The percentage of surviving participants will be presented.

• Overall Response Rate (ORR) Per RECIST 1.1 as Assessed by Blinded Central Imaging [ Time Frame: Through Database Cutoff Date of 20-May-2019 (Up to approximately 31.2 months) ]
  ORR was defined as the percentage of participants in the analysis population who had a Complete Response (CR: Disappearance of all target lesions) or a Partial Response (PR: ≥30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters) per RECIST 1.1. The percentage of participants who experienced a CR or PR is presented.
• Duration of Response (DOR) Per RECIST 1.1 as Assessed by Blinded Central Imaging [ Time Frame: From time of first documented evidence of CR or PR through database cutoff date of 20-May-2019 (Up to approximately 31.2 months) ]
  For participants who demonstrated a confirmed CR (disappearance of all target lesions) or PR (≥30% decrease in the sum of diameters of target lesions) per RECIST 1.1, DOR was defined as the time from first documented evidence of a CR or PR until PD or death. DOR for participants who had not progressed or died at the time of analysis was censored at the date of their last tumor assessment. Per RECIST 1.1, PD was defined as ≥20% increase in the sum of diameters of target lesions. In addition to the relative increase of 20%, the sum must also have demonstrated an absolute increase of ≥5 mm. Note: The appearance of one or more new lesions was also considered PD. DOR assessments were based on blinded central imaging review with confirmation. The DOR per RECIST 1.1 for all participants who experienced a confirmed CR or PR is presented.
• Number of Participants Who Experienced an Adverse Event (AE) [ Time Frame: Through Database Cutoff Date of 20-May-2019 (Up to approximately 31.2 months) ]
  An AE was defined as any untoward medical occurrence in a study participant administered study drug and which does not necessarily have to have a causal relationship with this study drug. The number of participants who experienced an AE is presented.
• Number of Participants Who Discontinued Any Study Drug Due to an AE [ Time Frame: Up to approximately 24 months ]
  The number of participants who discontinued any randomized study drug due to an AE is presented.

• Objective Response Rate (ORR) Per RECIST 1.1 as Assessed by Blinded Central Imaging [ Time Frame: Up to 24 months ]
  ORR is defined as the percentage of participants who have a Complete Response (CR: Disappearance of all target lesions) or a Partial Response (PR: At least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1. The percentage of participants who experience a CR or PR based on RECIST 1.1 will be presented.
• Duration of Response (DOR) Per RECIST 1.1 as Assessed by Blinded Central Imaging [ Time Frame: Up to 24 months ]
  For participants who demonstrate a confirmed complete response (CR: Disappearance of all target lesions) or confirmed Partial Response (PR: At least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1, DOR is defined as the time from first documented evidence of CR or PR until disease progression or death. DOR as assessed by blinded central imaging will be presented.
• Number of Participants Who Experience an Adverse Event (AE) [ Time Frame: Up to 27 months ]
  An AE is defined as any untoward medical occurrence in a participant administered study treatment which does not necessarily have to have a causal relationship with this treatment. The number of participants who experience an AE will be presented.
• Number of Participants Who Discontinue Study Treatment Due to an AE [ Time Frame: Up to 24 months ]
  An AE is defined as any untoward medical occurrence in a participant administered study treatment which does not necessarily have to have a causal relationship with this treatment. The number of participants who discontinue study treatment due to an AE will be presented.

This is a Japan Extension Study of Global Study MK-3475-189 (NCT02578680). This is an efficacy and safety study of pembrolizumab (MK-3475) combined with pemetrexed/platinum chemotherapy versus pemetrexed/platinum chemotherapy alone in adult Japanese participants with advanced or metastatic nonsquamous non-small cell lung cancer (NSCLC) who have not previously received systemic therapy for advanced disease. Participants will be randomly assigned to receive pembrolizumab combined with pemetrexed/platinum (Investigators choice of cisplatin or carboplatin), OR pemetrexed/platinum (Investigators choice of cisplatin or carboplatin).

The primary hypothesis is that pembrolizumab in combination with pemetrexed/platinum chemotherapy prolongs Progression-Free Survival (PFS) and Overall Survival (OS) compared to pemetrexed/platinum chemotherapy alone.

The MK-3475-189-Japan Extension Study will be identical to the global study (e.g. inclusion and exclusion criteria, study primary and secondary outcome measures and study procedures).

The MK-3475-189-Japanese Extension Study enrolled a total of 30 participants and the analyses included 10 participants (pembrolizumab =4; control = 6) that had been previously enrolled in the MK-3475-189 global study (NCT02578680), resulting in a total of 40 participants.

• Biological: Pembrolizumab 200 mg
  IV infusion
• Drug: Cisplatin
  IV infusion
• Drug: Carboplatin
  IV infusion
• Drug: Pemetrexed
  IV infusion
• Dietary Supplement: Folic acid 350-1000 μg
  Orally; at least 5 doses of folic acid must be taken during the 7 days preceding the first dose of pemetrexed, and folic acid dosing must continue during the full course of therapy and for 21 days after the last dose of pemetrexed.
• Dietary Supplement: Vitamin B12 1000 μg
  Intramuscular injection in the week preceding the first dose of pemetrexed and once every 3 cycles thereafter. Subsequent vitamin B12 injections may be given the same day as pemetrexed administration.
• Drug: Dexamethasone 4 mg
  For prophylaxis; orally twice per day (or equivalent). Taken the day before, day of, and day after pemetrexed administration.
• Drug: Saline solution
  IV infusion

• Experimental: Pembrolizumab
  Participants receive pembrolizumab 200 mg intravenously (IV) PLUS pemetrexed 500 mg/m^2 IV (with vitamin supplementation) PLUS cisplatin 75 mg/m^2 IV OR carboplatin Area Under the Curve (AUC) 5 IV on Day 1 of every 3-week cycle (Q3W) for 4 cycles followed by pembrolizumab 200 mg IV PLUS pemetrexed 500 mg/m^2 IV Q3W until progression (up to 35 treatment administrations; up to approximately 2 years).
  Interventions:

  • Biological: Pembrolizumab 200 mg
  • Drug: Cisplatin
  • Drug: Carboplatin
  • Drug: Pemetrexed
  • Dietary Supplement: Folic acid 350-1000 μg
  • Dietary Supplement: Vitamin B12 1000 μg
  • Drug: Dexamethasone 4 mg
• Active Comparator: Control
  Participants receive saline placebo IV PLUS pemetrexed 500 mg/m^2 IV (with vitamin supplementation) PLUS cisplatin 75 mg/m^2 IV OR carboplatin AUC 5 IV on Day 1 of every 3-week cycle (Q3W) for 4 cycles followed by saline placebo IV PLUS pemetrexed 500 mg/m^2 IV Q3W until progression. If documented progression occurs, participants may be able to receive pembrolizumab Q3W for the remainder of the study or until documented further progression (up to 35 treatment administrations; up to approximately 2 years).
  Interventions:

  • Drug: Cisplatin
  • Drug: Carboplatin
  • Drug: Pemetrexed
  • Dietary Supplement: Folic acid 350-1000 μg
  • Dietary Supplement: Vitamin B12 1000 μg
  • Drug: Dexamethasone 4 mg
  • Drug: Saline solution

Inclusion Criteria:

• Has a histologically-confirmed or cytologically confirmed diagnosis of stage IV nonsquamous NSCLC.
• Has confirmation that epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK)-directed therapy is not indicated.
• Has measurable disease.
• Has not received prior systemic treatment for their advanced/metastatic NSCLC.
• Can provide tumor tissue.
• Has a life expectancy of at least 3 months.
• Has a performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG) Performance Status.
• Has adequate organ function
• If female of childbearing potential, is willing to use adequate contraception for the course of the study through 120 days after the last dose of study medication or through 180 days after last dose of chemotherapeutic agents.
• If male with a female partner(s) of child-bearing potential, must agree to use adequate contraception starting with the first dose of study medication through 120 days after the last dose of study medication or through 180 days after last dose of chemotherapeutic agents.

Exclusion Criteria:

• Has predominantly squamous cell histology NSCLC.
• Is currently participating and receiving study therapy or has participated in a study of an investigational agent and received study therapy or used an investigational device within 4 weeks prior to administration of pembrolizumab.
• Before the first dose of study medication: a) Has received prior systemic cytotoxic chemotherapy for metastatic disease, b) Has received antineoplastic biological therapy (e.g. erlotinib, crizotinib, cetuximab), c) Had major surgery (<3 weeks prior to first dose)
• Received radiation therapy to the lung that is >30 Gray (Gy) within 6 months of the first dose of study medication.
• Completed palliative radiotherapy within 7 days of the first dose of study medication.
• Is expected to require any other form of antineoplastic therapy while on study.
• Received a live-virus vaccination within 30 days of planned start of study medication.
• Has clinically active diverticulitis, intra-abdominal abscess, gastrointestinal obstruction, peritoneal carcinomatosis.
• Known history of prior malignancy except if participant has undergone potentially curative therapy with no evidence of that disease recurrence for 5 years since initiation of that therapy, except for successful definitive resection of basal cell carcinoma of the skin, superficial bladder cancer, squamous cell carcinoma of the skin, in situ cervical cancer, or other in situ cancers.
• Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis.
• Previously had a severe hypersensitivity reaction to treatment with another monoclonal antibody (mAb).
• Known sensitivity to any component of cisplatin, carboplatin or pemetrexed.
• Has active autoimmune disease that has required systemic treatment in past 2 years.
• Is on chronic systemic steroids.
• Is unable to interrupt aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs), other than an aspirin dose ≤1.3 g per day, for a 5-day period (8-day period for long-acting agents, such as piroxicam).
• Is unable or unwilling to take folic acid or vitamin B12 supplementation.
• Had prior treatment with any other anti-programmed cell death-1 (PD-1), or PD-ligand 1 (PD-L1) or PD-L2 agent or an antibody targeting other immuno-regulatory receptors or mechanisms. Has participated in any other pembrolizumab study and has been treated with pembrolizumab.
• Has an active infection requiring therapy.
• Has known history of Human Immunodeficiency Virus (HIV).
• Has known active Hepatitis B or C.
• Has known psychiatric or substance abuse disorder that would interfere with cooperation with the requirements of the trial.
• Is a regular user (including "recreational use") of any illicit drugs or had a recent history (within the last year) of substance abuse (including alcohol).
• Has symptomatic ascites or pleural effusion.
• Has a history of (non-infectious) pneumonitis that required steroids or current pneumonitis.
• Is pregnant or breastfeeding, or expecting to conceive or father children within the projected duration of the study.