Bintrafusp Alfa and Doxorubicin Hydrochloride in Treating Patients With Advanced Sarcoma

This trial tests the combination of bintrafusp alfa (an immunotherapy drug that targets two immune checkpoints at once) plus doxorubicin (a chemotherapy) as a first-line treatment for advanced soft-tissue sarcoma (a cancer of connective tissues like muscle, fat, or blood vessels) that cannot be surgically removed or has spread. **You may be eligible if...** - You are 18 or older and have confirmed soft-tissue sarcoma (such as undifferentiated pleomorphic sarcoma, dedifferentiated liposarcoma, or leiomyosarcoma) - Your cancer has spread or cannot be surgically removed - You have not yet received any systemic (whole-body) treatment for your advanced/metastatic disease - Your overall fitness score is 0 or 1 (ECOG), and your expected survival is more than 3 months - You have at least one measurable tumor and are willing to have biopsies taken - Adequate blood, kidney, and liver function **You may NOT be eligible if...** - You have previously received chemotherapy or other systemic treatment for this advanced stage - You have a different type of sarcoma (e.g., with a known translocation) - You are pregnant or breastfeeding - You have significant heart, liver, or kidney problems Talk to your doctor to see if this trial is right for you.