Key Inclusion Criteria:  Males and females aged ≥ 18 years (or ≥ 19 years according to local regulatory guidelines) at the time of screening. Has adequate organ and marrow function as defined in protocol. Measurable disease as per RECIST v1.1. ECOG performance status 0-1. Adverse events related to any prior chemotherapy, radiotherapy, immunotherapy, other prior systemic anti-cancer therapy, or surgery must have resolved to Grade ≤1, except alopecia and Grade 2 peripheral neuropathy. HIV infected patients must be on anti-retroviral therapy (ART) and have a well-controlled HIV infection/disease as defined in protocol.  Key Exclusion Criteria:  Has known active CNS metastases and/or carcinomatous meningitis. An active second malignancy Has active or a known history of Hepatitis B or known active Hepatitis C virus infection. Has active tuberculosis or has a known history of active tuberculosis Active or uncontrolled infections, or severe infection within 4 weeks before study treatment administration. History of chronic liver disease or evidence of hepatic cirrhosis, except patients with liver metastasis. Has an active autoimmune disease that has required systemic treatment in past 2 years. Previous immunotherapies related to mode of action of GI-101. Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy or any other form of immunosuppressive medications within 2 weeks prior to Cycle 1 Day 1. Administration of prior systemic anti-cancer therapy including investigational agents within 4 weeks prior to treatment. Radiotherapy within the last 2 weeks before start of study treatment administration, with exception of limited field palliative radiotherapy (except Part D). Administration of a live, attenuated vaccine within 4 weeks before Cycle 1 Day 1. Known hypersensitivity to any of the components of the drug products and/or excipients of GI-101, pembrolizumab or lenvatinib.  Other protocol defined inclusion exclusion criteria may apply