A Study of Emiltatug Ledadotin (Emi-Le) in Participants With Solid Tumors

This first-in-human (FIH) study will test the safety, side effects, and antitumor activity of a drug called Emi-Le ((Emiltatug Ledadotin, formerly 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 three parts. The first part called Dose Escalation, will find out how much Emi-Le 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 Emi-Le is and if it works to treat solid tumors. The third part, the Phase 2 part of the trial, called EMBLEM-1, will find out if Emi-Le works to treat aggressive Adenoid Cystic Carcinoma and continue to check how safe Emi-Le is.