This clinical trial is focused on studying a type of cancer known as soft-tissue sarcoma, which is a cancer that begins in the tissues that connect, support, or surround other structures and organs of the body. The study is specifically for patients whose cancer cannot be removed by surgery or has spread to other parts of the body, and who have already tried at least two other treatments without success. The trial will test a new treatment combination to see if it can help these patients. The treatment being studied includes a new drug called L19TNF, which is a fusion of a human antibody and a protein that can target tumors, and it will be used together with another drug called dacarbazine, which is a chemotherapy medication.

The purpose of the study is to find out if the combination of L19TNF and dacarbazine can help patients live longer without their cancer getting worse, compared to using dacarbazine alone. Patients in the study will receive the treatment through an intravenous infusion, which means the medication will be given directly into a vein. Some patients will receive the combination of both drugs, while others will receive only dacarbazine or a placebo. The study will last for a period of up to 48 weeks, during which time patients will be monitored regularly to check on their health and the progress of their cancer.

Throughout the study, doctors will look at how well the treatment works by measuring how long patients live without their cancer getting worse, which is known as progression-free survival. They will also look at overall survival, which is the length of time patients live after starting the treatment. This study aims to provide new insights into the treatment of advanced or metastatic soft-tissue sarcoma and potentially offer a new option for patients who have not had success with other treatments.