This first-in-human (FIH) study will test the safety and side effects of a drug called XMT-1660. A side effect is anything a drug does to the body besides treating the disease.~Participants in the study will have cancer that has come back after a period of time during which the cancer could not be detected (recurrent), spread in the body near where it started (advanced) or spread through the body (metastatic).~The study will have two parts. The first part called Dose Escalation will find out how much XMT-1660 should be given to participants. The second part called Dose Expansion will use the dose found in the first part to find out how safe XMT-1660 is and if it works to treat solid tumor cancers.
A Study of XMT-1660 in Solid Tumors