The purpose of this study is to assess the safety and tolerability and the pharmacokinetics (PK) of INCMGA00012 (PD-1 Inhibitor), INCB001158 (Arginase Inhibitor), and the combination in Japanese participants with advanced solid tumor malignancies.

Inclusion Criteria:

• Participant is Japanese
• Histologically or cytologically confirmed diagnosis of any locally advanced or metastatic solid tumors not amenable to local or other curative therapy.
• Participants with nonevaluable lesions are allowed.
• Life expectancy > 3 months.
• Eastern Cooperative Oncology Group performance status 0 to 1.
• Female participants agree to use medically acceptable contraceptive measures, should not be breastfeeding, and must have a negative pregnancy test before the start of study drug administration.
• Female participants of childbearing potential must understand and accept that pregnancy must be avoided during participation in the study.
• Male participants should avoid unprotected sex with women of childbearing potential and refrain from donating sperm during participation the study.

Exclusion Criteria:

• Receipt of anticancer therapy or participation in another interventional clinical study within 14 days before the first administration of study drug with the following exceptions: Immunotherapy or biological therapy (eg, monoclonal antibodies) within 21 days the first administration of study drug; 6 weeks for mitomycin-C or nitrosoureas; 7 days for tyrosine kinase inhibitors.
• Radiotherapy within 14 days of first dose of study treatment with the following exceptions: 28 days for pelvic radiotherapy; 6 months for thoracic region radiotherapy that is > 30 Gy.
• Toxicity of prior therapy and/or complications from surgical intervention that has not recovered to ≤ Grade 1 or baseline within 7 days before starting study drug treatment (with the exception of anemia not requiring transfusion support and any grade of alopecia). Note: Endocrinopathy, if well-managed, is not exclusionary and should be discussed with sponsor medical monitor.
• Receipt of prior systemic treatment with an arginase inhibitor
• Immune-related toxicity during prior checkpoint inhibitor therapy for which permanent discontinuation of therapy is recommended (per product label or consensus guidelines), OR any immune-related toxicity requiring intensive or prolonged immunosuppression to manage (with the exception of endocrinopathy that is well controlled on replacement hormones).
• Active autoimmune disease requiring systemic immunosuppression in excess of physiologic maintenance doses of corticosteroids (> 10 mg of prednisone or equivalent).
• Known active central nervous system metastases and/or carcinomatous meningitis.
• Known active hepatitis A virus, hepatitis B virus, or hepatitis C virus infection.
• Known HIV infection.
• Active infections requiring systemic therapy.
• Known hypersensitivity to another monoclonal antibody that cannot be controlled with standard measures and/or known hypersensitivity ≥ Grade 3, or severe reaction, to study treatments or any of their excipients or additives.
• Participants with impaired cardiac function or clinically significant cardiac disease.
• Evidence of interstitial lung disease or active, noninfectious pneumonitis or a history of interstitial lung disease.
• Participant is pregnant or breastfeeding.