PRIMARY OBJECTIVE:~I. To evaluate the efficacy of sintilimab in subjects with angiosarcoma (progression- free rate PFR at 9 cycles by Response Evaluation Criteria in Solid Tumors [RECIST] 1.1).~SECONDARY OBJECTIVE:~I. To evaluate the objective response rate (ORR), stable disease rate (SDR), progression free survival (PFS), overall survival (OS), quality of life (QOL), safety and duration of response (DOR) of sintilimab in subjects with angiosarcoma.~EXPLORATORY OBJECTIVES:~I. To evaluate the correlation between biomarkers in tumor tissue and efficacy, including but not restricted to PD-L1 expression level, transcriptome sequencing, single-cell sequencing, and multicolor immunohistochemistry (IHC) analyses.~II. To evaluate the correlation between biomarkers in peripheral blood and efficacy, including but not restricted to soluble PD-L1, circulating tumor deoxyribonucleic acid (DNA) (ctDNA), and cytokine analyses.~OUTLINE:~Patients receive sintilimab intravenously (IV) over 30-60 minutes on day 1. Cycles repeat every 21 days for up to 24 months in the absence of disease progression or unacceptable toxicity. Patients with progressive disease may continue to receive treatment at the discretion of the treating physician.~After completion of study treatment, patients are followed up at 30 and 90 days, and then every 60 days for up to 3 years.
This phase II trial evaluates the effect of sintilimab in treating patients with angiosarcoma that has spread to nearby tissue or lymph nodes (locally advanced), has spread to other places in the body (metastatic), or has come back (recurrent). Immunotherapy with monoclonal antibodies, such as sintilimab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving sintilimab may help to control angiosarcoma.