A Study of OTP-01, a Dual Paratopic PD-1/VEGFR2 Antibody, in Patients With Advanced Solid Tumors

The main goals of this clinical trial are to find out what the best dose of the study drug, OTP-01, is for patients with solid tumors through understanding how it is tolerated and any side effects that it may cause. The trial will also see if OTP-01 causes tumors to shrink and how the body processes OTP-01 by measuring drug levels in the blood. The main questions this study aims to answer are: * What is the recommended dose of OTP-01 for adults with solid tumors? * Is OTP-01 safe and tolerable? * Does OTP-01 reduce tumor growth? Participants will: * Receive OTP-01 through an infusion into a vein. Doses will be spaced out and never more than once a week. * Have blood tests to evaluate safety and drug levels of OTP-01. These will be done often at first and then less frequently as treatment continues. * Have radiographic scans of their tumor at baseline and during the study at regular intervals. * Have the choice to have an optional tumor biopsy before and after treatment to help researchers understand how OTP-01 affects cancer and the immune system. These biopsies are voluntary and will not affect participation in the study.