Propranolol and Pembrolizumab in Advanced Soft Tissue Sarcoma Patients

This study is testing whether adding propranolol (a common beta-blocker heart medication) to pembrolizumab (a well-known immunotherapy drug) improves outcomes in people with advanced soft tissue sarcomas — specifically angiosarcoma or undifferentiated pleomorphic sarcoma — that have stopped responding to standard chemotherapy. **You may be eligible if...** - You are 18 or older with a confirmed diagnosis of unresectable locally advanced or metastatic angiosarcoma or undifferentiated pleomorphic sarcoma - Your cancer has progressed after at least one line of standard chemotherapy - Your overall health is acceptable (ECOG 0–2) and organ function meets required levels - You have measurable tumor(s) by standard imaging **You may NOT be eligible if...** - You have moderate-to-severe asthma or severe COPD (propranolol can worsen these conditions) - You have acute or unstable heart failure - You have previously received pembrolizumab or any other PD-1/PD-L1 immunotherapy - You have received propranolol within the past 4 weeks - You have active autoimmune disease requiring systemic treatment (with some exceptions for mild conditions) - You have HIV or AIDS - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.