Response to nivolumab in radiation induced, BRCA-2 N372H variant, programed death ligand-1 negative, pleomorphic undifferentiated sarcoma.

61Background: Early results from recent studies using immune checkpoint blockade targeting programmed death 1 (PD-1) have suggested that pleomorphic undifferentiated sarcomas may have response rates of over 40%. As of now predictive biomarkers for response and resistance have been incompletely characterized. Methods: A 58-year-old man who received radiation for a head and neck squamous cell cancer, developed a radiation-induced undifferentiated pleomorphic sarcoma (UPS) in his neck in 2014. His sarcoma was resected but recurred in 2015. He received adjuvant radiation after surgical debulking in September 2015 and was found on radiation simulation scan to have new widespread metastatic disease involving liver, lung, and bone. He started treatment on nivolumab in November 2015 and has had a sustained near complete response in all lesions. Results: All sites had a near complete response to nivolumab treatment. Pre treatment tissue analysis revealed no mutations or amplifications in 134 cancer-related genes, ...