Responses to Immune Checkpoint Therapy in Pulmonary Sarcomatoid Carcinoma: A Retrospective Review.

115 Background: Advanced Pulmonary Sarcomatoid Carcinoma (PSC) is associated with poor response to chemotherapy and a median survival of 4-6 months. PSC have a high frequency of PD-L1 positivity and high tumor mutational burden, which are markers of benefit with immune checkpoint inhibitors (ICPI). The parameters of response and survival for PSC treated in the era of immune checkpoint inhibition are unknown. Methods: A review of all cases of advanced PSC diagnosed at two institutions in Bronx, NY between 6/2015-6/2018 was performed. Responses were assessed by serial imaging obtained during routine care and graded by RECIST criteria v 1.1. Results: Five cases of advanced Stage IV PSC are reported. The median age was 57 years and all had received ICPI. All cases were smokers with a median of 30 pack-years and TPS > 75%. Three patients received Pembrolizumab as front-line therapy. Responses were seen in four out of five patients, including one complete response. The fifth patient had prolonged disease stability. After a median follow-up of 13 months, none of the patients had progressed. One patient died of infectious complications after 23 months with no evidence of progression. Four patients continue to be alive with ongoing OS ranging between 14-33 months. Conclusions: ICPI therapy has robust activity in advanced PSC and offers an effective line of therapy in this treatment-refractory aggressive malignancy. [Table: see text]