A Study of INCMGA00012 in Participants With Selected Solid Tumors (POD1UM-203)

Inclusion Criteria: * Confirmed diagnosis of one of the following: treatment-naïve metastatic non-small cell lung cancer with high PD-L1 expression (tumor proportion score ≥ 50%) and no epidermal growth factor receptor (EGFR), alkaline phosphatase (ALK), or ROS activating genomic tumor aberrations; locally advanced or metastatic urothelial carcinoma in participants who are not eligible for cisplatin therapy and whose tumors express PD-L1 with a combined positive score ≥ 10; unresectable or metastatic melanoma; locally advanced or metastatic renal cell carcinoma with clear cell component (with or without sarcomatoid features) and having received no prior systemic therapy. * Measurable disease per RECIST v1.1. * Eastern Cooperative Oncology Group performance status 0 to 1. * Willingness to avoid pregnancy or fathering children. Exclusion Criteria: * Receipt of anticancer therapy or participation in another interventional clinical study within 21 days before the first administration of study drug. * Prior treatment with PD-1 or PD-L1 directed therapy (other immunotherapies may be acceptable with prior approval from the medical monitor). * Radiotherapy within 14 days of first dose of study treatment with the following caveats: 28 days for pelvic radiotherapy; 6 months for thoracic region radiotherapy that is \> 30 Gy. * Toxicity of prior therapy that has not recovered to ≤ Grade 1 or baseline (with the exception of anemia not requiring transfusion support and any grade of alopecia). Endocrinopathy, if well-managed, is not exclusionary and should be discussed with sponsor medical monitor. * Has not recovered adequately from toxicities and/or complications from surgical intervention before starting study drug. * Laboratory values outside the protocol-defined range at screening. * Known additional malignancy that is progressing or requires active treatment, or history of other malignancy within 3 years of study entry. * Active autoimmune disease requiring systemic immunosuppression in excess of physiologic maintenance doses of corticosteroids (\> 10 mg of prednisone or equivalent). * Evidence of interstitial lung disease or active noninfectious pneumonitis. * Known active central nervous system metastases and/or carcinomatous meningitis. * Known active hepatitis B antigen, hepatitis B virus, or hepatitis C virus infection. * Active infections requiring systemic therapy. * Known to be HIV-positive, unless all of the following criteria are met: CD4+ count ≥ 300/μL, undetectable viral load, receiving antiretroviral therapy. * Known hypersensitivity to another monoclonal antibody that cannot be controlled with standard measures (eg, antihistamines and corticosteroids). * Impaired cardiac function or clinically significant cardiac disease. * Is pregnant or breastfeeding. * Has received a live vaccine within 28 days of the planned start of study drug.