Key Inclusion Criteria:  At least 18 years of age Participants must have histologically confirmed locally advanced, recurrent, or metastatic solid tumor malignancies that cannot be treated with curative intent (surgery or radiotherapy) At least 1 lesion of measurable disease Demonstrated adequate organ function at screening Life expectancy >12 weeks as determined by the Investigator Eastern Cooperative Oncology Group (ECOG) performance status 0, 1, or 2 Participants who have undergone treatment with anti-PD-1, anti-PD-L1, or anti-CTLA-4 antibody must have at least 4 weeks from the last dose of antibody and evidence of disease progression per investigator assessment before Cycle 1 Day 1 (C1D1) Participants who have previously received an immunotherapy prior to C1D1 must have any immune-related toxicities resolved to ≤Grade 1 or baseline (prior to the immunotherapy) to be eligible, with the exception of participants well controlled on physiologic endocrine replacement Female and male participants of childbearing potential who are sexually active must agree to use highly effective methods of contraception  Key Exclusion Criteria:  Symptomatic central nervous system metastases Active autoimmune diseases, regardless of need for immunosuppressive treatment at the time of screening, with the exception of participants well controlled on physiologic endocrine replacement Any uncontrolled bacterial, fungal, viral, or other infection Significant cardiac disease A marked baseline prolongation of QT/QTc interval (e.g., repeated demonstration of a QTc interval >480 ms) [CTCAE Grade 1]) using Fridericia's QT correction formula Positive for HIV or has known active hepatitis B or C infection Known hypersensitivity to any study treatment(s) used in the specific study part/cohort Participants who have been previously treated with IL-2 or IL-2 variants Systemic immunosuppressive treatment with the exception for patients on corticosteroid taper (for example, for chronic obstructive pulmonary disease exacerbation). Participants cannot start dosing on study until steroid dose is at or lower than 10 mg per day prednisone or equivalent Vaccination with live, attenuated vaccines within 4 weeks of C1D1 Treatment with any other anti-cancer systemic treatment (approved or investigational) or radiation therapy within 4 weeks of first dosing on study is not allowed Women who are breastfeeding or have a positive serum pregnancy test during screening or within 72 hours prior to C1D1 are not eligible