Inclusion Criteria:  Disease Criteria - Phase 1: Any histologically or cytologically confirmed solid tumor malignancy that is locally advanced or metastatic and has failed standard therapy, or standard therapy is not curative or available Phase 2, Part 2a: Patients with metastatic RCC who have previously been treated with an approved anti-PD-1 and a TKI. Patients must have progressed on treatment with an anti-PD-1 mAb administered either as monotherapy or in combination with other therapies Phase 2, Part 2b: Patients with unresectable or metastatic melanoma who have previously been treated with an approved anti-PD-1 and an anti-CTLA4 checkpoint inhibitor ECOG performance status of 0 or 1 Adequate organ function  Exclusion Criteria:  Received prior treatment with IL-2 therapy History of clinically significant pulmonary disease History of clinically significant cardiovascular disease Has a diagnosis of immunodeficiency Has an active autoimmune disease that has required systemic treatment in past 2 years, including the use of disease modifying agents, corticosteroids or immunosuppressive drugs Has an active infection requiring systemic therapy within 4 weeks prior to study treatment