PRIMARY OBJECTIVE:~I. Determine the objective response rates (ORR) using Response Evaluation Criteria in Solid Tumors (RECIST) version (v) 1.1 of atezolizumab in adult (>= 18 years) patients with clear cell sarcoma (CCS) and chondrosarcoma (CS).~SECONDARY OBJECTIVES:~I. Determine duration of response (DOR) using RECIST v 1.1 and/or change in clinical symptoms (time frame: baseline until disease progression, death, loss to follow-up, initiation of another anti-cancer treatment, withdrawal of consent, or study termination).~II. Measure progression-free survival (PFS) time (time frame: baseline until disease progression, death, loss to follow-up, initiation of another anti-cancer treatment, withdrawal of consent, or study termination).~III. Assess the number of activated CD8+ T cells infiltrating the tumor before and after atezolizumab treatment, and correlate treatment-induced changes with clinical response.~EXPLORATORY OBJECTIVES:~I. Compare RECIST v 1.1 versus (vs) immune RECIST (iRECIST) in patients with CCS and CS on atezolizumab.~II. Examine changes in PD-1/PD-L1 expression in the tumor microenvironment before and after atezolizumab treatment, and correlate treatment-induced changes with clinical response.~III. Evaluate potential associations between atezolizumab activity and tumor genomic alterations.~OUTLINE:~Patients receive atezolizumab intravenously (IV) over 30-60 minutes on day 1. Cycles repeat every 21 days in the absence of disease progression or unacceptable toxicity. Patients undergo computed tomography (CT) scans and undergo biopsy and collection of blood samples on study.~After completion of study treatment, patients are followed up to 90 days.
This phase II trial studies how well atezolizumab works in treating patients with chondrosarcoma or clear cell sarcoma that is newly diagnosed, cannot be removed by surgery (unresectable), or has spread to other places in the body (metastatic). Immunotherapy with monoclonal antibodies, such as atezolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread.