A Study of Ramucirumab Plus Pembrolizumab in Participants With Gastric or GEJ Adenocarcinoma, NSCLC, Transitional Cell Carcinoma of the Urothelium, or Biliary Tract Cancer

Inclusion Criteria:

* Metastatic disease or locally advanced, unresectable disease.

  * Has histopathologically confirmed gastric or GEJ adenocarcinoma with documented disease progression after 0-2 prior lines of systemic therapy
  * Has histopathologically confirmed nonsquamous or squamous NSCLC with documented disease progression after 0-3 prior lines of systemic therapy
  * Has histopathologically confirmed transitional cell carcinoma of the urothelium (bladder, urethra, or renal pelvis) with documented disease progression after 1-3 prior lines of systemic therapy
  * Has histologically confirmed biliary tract adenocarcinoma with documented progression after 1-2 prior lines of systemic therapy
* Availability of tumor tissue for biomarker analysis from a newly obtained core or excisional biopsy or willing to undergo a tumor biopsy. For first line NSCLC participants only, PD-L1 expression should be 1% or higher.
* Have an Eastern Cooperative Oncology Group Performance Status of 0 or 1.
* Has adequate organ function.
* Have an anticipated life expectancy of ≥3 months.

Exclusion Criteria:

* Have known brain metastases.
* Has received ≥3 lines of prior systemic therapy for gastric or GEJ adenocarcinoma and BTC or ≥4 lines for NSCLC or urothelial cancer.
* Has active autoimmune disease.
* Known human immunodeficiency virus (HIV) infection.
* Known active hepatitis B or hepatitis C infection.
* Has received any previous systemic therapy targeting vascular endothelial growth factor (VEGF) or VEGF receptor, or programmed death (PD) 1 or PD-ligand 1/2 signaling pathways.
* Have received a live vaccine within 30 days prior to enrollment. Seasonal flu vaccines that do not contain live virus are permitted.
* Have had a serious or non-healing wound, ulcer, or bone fracture within 28 days prior to enrollment.
* Have an elective or a planned major surgery during the course of the trial or has undergone major surgery within 28 days prior to enrollment.