Additional Study Information: This research study mainly aims to test the safety and tolerability of AGEN1181 and balstilimab and to determine the most appropriate dose of the study drug AGEN1181 alone and in combination with balstilimab. AGEN1181 targets cells that are a part of the body's immune system to block a protein called cytotoxic T-lymphocyte-associated protein-4 (CTLA-4). Balstilimab can specially block a protein called programmed-death 1 (PD-1) and prevent communication between this protein and receptors on the tumor cells. These receptors are known to affect the body's defense mechanism to identify and fight against cancerous cells. Blocking these proteins is believed to improve the ability of your immune system to fight your cancer. The study drugs are investigational meaning that a regulatory authority, such as the U.S. Food and Drug Administration (FDA), has not approved the study drugs for use in people.