Study Purpose: This study is testing two treatments for a type of cancer called metastatic leiomyosarcoma (LMS). One group will get a combination of two medicines, lurbinectedin and doxorubicin, while the other group will only get doxorubicin. The goal is to see which treatment works better at stopping the cancer from getting worse.

Metastatic leiomyosarcoma is a cancer that begins in smooth muscle cells and spreads to other parts of the body. Doxorubicin is a common chemotherapy drug, and lurbinectedin is a newer medicine being tested.

• Participants must be 18 years or older with confirmed LMS, and they can't have had certain treatments before.
• The study involves regular hospital visits and monitoring to check how well the treatment is working.
• Participants will receive either the combination treatment or doxorubicin alone.

By joining the study, you might get access to a new treatment that could help your cancer. However, you should be aware of potential side effects and the need for frequent hospital visits.