Phase 1a Part of the trial will consist cohorts, one dosed every 3 weeks at increasingly higher doses following a standard 3+3 design. Part A is the dose finding portion of the trial.~18 - 36 patients will be enrolled.~Phase 1b Part consists of 1 cohort of approximately 40 patients . For Part B, participants must have GREM1 positive locally advanced or metastatic esophageal cancer (EC), gastric cancer (GC), colorectal cancer (CRC), castration-resistant prostate cancer (CRPC), breast cancer (BC), non-small cell lung cancer (NSCLC) or other type of solid tumors.~The trial will last approximately 3 years, with assessments including but not limited to safety labs, ECGs, MUGA scans, PKs and PDs and CT/MRI tumor assessments, based on emerging data found in Part A.
The goal of this clinical trial is to test the safety of TST003 in patients with cancer.~The main question[s] it aims to answer are:~What is the recommended dose patients can safely receive?~How long does this drug remain in the body after administration?~What are the side effects of this drug?~Does your cancer respond to TST003?~Participants on this study will get TST003 intravenously (through a needle into your vein), once every 3 weeks.~You may need to come to the study site 2-4 times to have tests to see if you are eligible to be in the study before you begin to receive the study drug.~After you start the study drug, you will need to return to the site several times after each dose so the physician can take vital signs, draw blood samples, and evaluate you for safety and wellbeing.~Participants will continue taking the drug as long as they are receiving clinical benefit.~At the end of your study participation, additional testing is required.