Additional Study Information: This research study is studying a drug called AGEN2373 as a possible treatment for advanced cancer. The study drug targets cells that are a part of the body's immune system to block a protein called anti-CD137 agonist antibody. Blocking this protein is believed to improve the ability of your immune system to fight your cancer. This drug has been tested in animals. This is the first time that the Study Drug will be given to humans. The study will also evaluate how the body breaks down the study drug (pharmacokinetics or PK) and what is the effect of the study drug on the body (pharmacodynamics). In addition, the study will investigate the potential effectiveness of the study drug and if your body is producing certain substances (known as antibodies) against the study drug (anti-drug antibodies). It will also study certain proteins that give more information about the disease and/or the body's response to the disease. These specific proteins are known as biomarkers. Cancers include: Bladder cancer, breast cancer, colon and rectal cancer, cervical cancer, ovarian cancer, kidney/adrenal cancer, liver cancer, lung cancer, melanoma, pancreatic cancer, prostate cancer, and stomach cancer.