Study of Pembrolizumab (MK-3475) Compared to Platinum-Based Chemotherapies in Participants With Metastatic Non-Small Cell Lung Cancer (MK-3475-024/KEYNOTE-024)

Treatment Phase: Participants randomized to pembrolizumab will be treated for up to 35
cycles or until documented progressive disease (PD) occurs. Participants randomized to SOC
chemotherapies will be treated with their randomized study drug for up to 4-6 cycles. After
this, participants with non-squamous histologies may choose to be treated with maintenance
pemetrexed for the remainder of the study or until PD occurs. For the SOC chemotherapy
participants, If documented PD occurs, these participants may be eligible for the Cross-Over
Phase. Cross-Over Phase: This is only applicable for participants randomized to SOC who have
documented PD. Participants will be treated with pembrolizumab for the remainder of the
study or until PD occurs.

Inclusion Criteria:

- Histological or cytological diagnosis of Stage IV NSCLC lacking epidermal growth
factor receptor (EGFR)-sensitizing mutation and/or anaplastic lymphoma kinase (ALK)
translocation, and received no prior systemic chemotherapy treatment for their
metastatic NSCLC

- At least one radiographically measurable lesion per RECIST 1.1

- Life expectancy of at least 3 months

- Performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG)
Performance Status

- Adequate organ function

- No history of prior malignancy, with the exception of basal cell carcinoma of the
skin, superficial bladder cancer, squamous cell carcinoma of the skin, or in situ
cervical cancer, or has undergone potentially curative therapy with no evidence of
that disease recurrence for 5 years since initiation of that therapy

- Provided newly obtained formalin fixed tumor tissue from a biopsy of a tumor AFTER
the diagnosis of metastatic disease has been made AND from a site not previously
irradiated

- PD-L1 strong expressing tumor as determined by immunohistochemistry (IHC) at a
central laboratory

- Female participants must have a negative pregnancy test at screening if of
childbearing potential or be of non-childbearing potential

- Female participants of childbearing potential and male partners with female partners
of childbearing potential must agree to use 2 adequate barrier methods of
contraception during the study and for 120 days after last dose of study drug and up
to 180 days after last dose of chemotherapy

Exclusion Criteria:

- EGFR sensitizing mutation and/or ALK translocation

- Currently participating or has participated in a study of an investigational agent or
using an investigational device within 30 days of first dose of study drug

- Tumor specimen is not evaluable for PD-L1 expression by the central laboratory

- Receiving systemic steroid therapy <= 3 days prior to first dose of study drug or
receiving any other form of immunosuppressive medication

- Expected to require any other form of systemic or localized antineoplastic therapy
during the study

- Received prior systemic cytotoxic chemotherapy, biological therapy, major surgery
within 3 weeks of first dose of study drug; received thoracic radiation therapy of >
30 gray (Gy) within 6 months of first dose of study drug

- Received prior therapy with an anti-programmed cell death protein 1 (anti-PD-1),
anti-PD-L1, anti-programmed cell death-ligand 2 (anti-PD-L2), anti-CD137 (4-1BB
ligand, a member of the Tumor Necrosis Factor Receptor [TNFR] family), or
anti-Cytotoxic T-lymphocyte-associated antigen-4 (anti-CTLA-4) antibody (including
ipilimumab or any other antibody or drug specifically targeting T-cell co-stimulation
or checkpoint pathways)

- Has untreated central nervous system (CNS) metastases and/or carcinomatous meningitis

- Active autoimmune disease that has required systemic treatment in past 2 years

- Allogenic tissue/solid organ transplant

- Interstitial lung disease or pneumonitis that has required oral or IV steroids

- Received or will receive a live vaccine within 30 days prior to first dose of study
drug

- Active infection requiring IV systemic therapy

- Known history of human immunodeficiency virus (HIV)

- Known active tuberculosis, or hepatitis B or C

- Known psychiatric or substance abuse disorders that would interfere with cooperation
with the requirements of the study

- Pregnant or breastfeeding, or expecting to conceive or father children during the
study and through 120 days after last dose of study drug

- Immediate family member who is investigational site or sponsor staff directly
involved with this study