This research study is testing a drug called mifomelatide, also known as TCMCB07, on people with newly diagnosed colorectal cancer (CRC) or pancreatic ductal adenocarcinoma (PDAC) who are getting chemotherapy. The study aims to see if the drug helps maintain body weight and muscle mass. There are two parts to this study: a 12-week double-blind phase, where neither the doctor nor the patient knows who is getting the drug or a placebo, and an optional Open Label Extension (OLE) phase, which can last up to 26 weeks, where everyone knows they are getting the drug.

• The study involves daily injections and includes a 12-week initial phase, with an optional 26-week extension.
• Participants will be randomly chosen to receive one of three doses or a placebo to compare effects.
• Eligibility requires being 18 or older, having a certain health status, and being on specific chemotherapy regimens.