Nonconventional responses and survival benefit of immunotherapy in advanced lung cancer.

e14572 Background: Objective response rates (ORR) utilizing RECIST or WHO criteria have been traditionally used as clinical endpoints to assess efficacy of cytotoxic chemotherapy. However in the era of immunotherapeutic agents, response rate assessment can be misleading due to nonconventional responses resulting in premature discontinuation of treatment. Wolchok et al proposed immune-related response criteria (irRC) to assess immune responses in melanoma. He also noted that stable disease which is not indicative of antitumor activity could be a potential surrogate marker of better clinical outcome. Brahmer et al reported nonconventional pattern of responses with Nivolumab in lung cancer. Methods: A retrospective chart review was done to assess differences in responses utilizing both RECIST v1.1 and irRC criteria in lung cancer patients treated with Nivolumab. Patients who received minimum of 4 cycles of Nivolumab were included in the study. The CT scans were reviewed by a senior radiologist. We reviewed 64 patients treated with Nivolumab between 4/30/2015 to 6/21/2016 and 30 patients were found eligible. Results: Patient characteristics. Male 53%; median age 61 years; squamous 47%; adeno 40%; small cell 13%; Median cycles of Nivolumab 6. Response rates utilizing both criteria was essentially similar with only 2 patients showing dis-concordant responses (6.6%). We utilized RECIST responses criteria for further analysis. Partial response (PR) 2/30; stable disease (SD) 12/30; progressive disease (PD) 15/30 and not evaluable (NE) 1/30. ORR 6.6%. Kaplan–Meier curve was used to analyze difference in survival between patients with PR+SD and PD. The median survival for PD was 9 months and PR+SD was not reached at median follow up of 1 year. Overall survival at 1 year for PD 33% and PR+SD 60% (p = 0.048). Hazard ratio for PD was 3.060 (p = 0.60). Conclusions: Patients with stable disease had a better survival and should be considered as responders though traditionally not included in the ORR. However irRC did not help in differentiating nonconventional immune responses in lung cancer patients. [Table: see text]