Inclusion Criteria:

          -  For Part A Japanese cohort added with Amendment 7: Must reside in Japan and be of
             Japanese descent and have adenocarcinoma of the stomach and/or gastric-esophageal
             junction (GEJ) that is considered inoperable and that has received, and progressed on,
             at least 1 prior chemotherapy regimen or human epidermal growth factor receptor 2
             (HER2)/neu-targeted approved therapy (if HER2/neu-positive). In both cases,
             participants may be untreated or could have received and progressed on 1 prior
             regimen, but must not have received prior anti-PD-1/PD-L1 therapy

          -  For Part A participants with NSCLC added with Amendment 7: Must have a histologically
             or cytologically confirmed diagnosis of stage IV (M1a or M1b per current AJCC
             criteria, edition 8) non-squamous NSCLC

          -  For Parts A and B: Has histologically or cytologically confirmed metastatic solid
             tumor

          -  Has measureable disease by Response Evaluation Criteria In Solid Tumors (RECIST)

          -  Has an Eastern Cooperative Oncology Group performance status of 0 to 1

          -  Females must not be pregnant

          -  Women of childbearing potential and male participants must agree to use adequate
             contraception for the course of the study

          -  Has provided a tumor tissue sample (archival or newly obtained core or excisional
             biopsy of a tumor lesion)

        Exclusion Criteria:

          -  Has had chemotherapy, radiation, biological cancer therapy or major surgery within 4
             weeks prior to the first dose of study treatment

          -  Has not recovered to Common Toxicity Criteria for Adverse Events Grade 1 or better
             from the adverse events due to cancer therapeutics administered more than 4 weeks
             prior to the first dose of study treatment

          -  Is currently participating in or has participated in a study of an investigational
             agent or has used an investigational device within 4 weeks prior to the first dose of
             study treatment

          -  Has received previous treatment with another agent targeting the T cell immunoglobulin
             and immunoreceptor tyrosine-based inhibitory motif (TIGIT) receptor

          -  Has received previous treatment with an immunomodulatory agent (e.g., anti-programmed
             cell death 1/ anti-programmed cell death ligand 1 or cytotoxic T-lymphocyte-associated
             protein 4) and was discontinued from that treatment due to a Grade 3 or higher
             immune-related adverse event

          -  Is expected to require any other form of antineoplastic therapy while participating in
             the trial

          -  Is on chronic systemic steroid therapy in excess of replacement doses or on any other
             form of immunosuppressive medication.

          -  Has a history of a previous additional malignancy unless potentially curative
             treatment has been completed with no evidence of malignancy for 5 years

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

          -  Has an active autoimmune disease

          -  Has an active infection requiring systemic treatment

          -  Has interstitial lung disease

          -  Has active or past history of (non-infectious) pneumonitis requiring steroids

          -  Has symptomatic ascites or pleural effusion

          -  Has previously had a hematopoetic stem cell transplant or solid organ transplant

          -  Is known to be human immunodeficiency virus (HIV) positive and/or known to have active
             chronic or acute Hepatitis B or Hepatitis C

          -  Has a known psychiatric and/or substance abuse disorder that would make it difficult
             for the participant to cooperate with the requirements of the trial

          -  Is a regular user (including recreational use) of any illicit drugs at the time of
             signing informed consent, or has a recent history (within the last year) of substance
             abuse

          -  Has received a live-virus vaccine within 30 days prior to the first dose of study
             treatment

          -  Has had hormonal cancer therapy (e.g., tamoxifen, leuprolide). within 4 weeks prior to
             the first dose of study treatment

          -  For Part A participants with NSCLC added with Amendment 7: Is unable to interrupt
             aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) other than an aspirin
             dose ≤1.3 gram per day for a 5-day period (8-day period for long-acting agents, such
             as piroxicam)

          -  For Part A participants with NSCLC added with Amendment 7: Is unable or unwilling to
             take folic acid or Vitamin B12 supplementation