Immune checkpoint inhibitor in nasopharyngeal carcinoma: Multi-institution experience.

Abstract

6538 Background: The current standard treatment for unresectable recurrent/metastatic (R/M) nasopharyngeal carcinoma (NPC) is cytotoxic chemotherapy but prognosis remains poor. Recent phase I-II trials of anti-PD-1 therapy (aPD-1) have demonstrated promising activity in R/M NPC, but the published experience is primarily limited to Epstein-Barr virus (EBV) positive tumors in the Asian population. Here we report our three institutional real-world experience with aPD-1 in patients (pts) with R/M NPC. Methods: A retrospective analysis was conducted after IRB approval at the Massachusetts General, Johns Hopkins, and University California San Francisco Hospitals. Demographic and clinical data was collected on pts with R/M NPC who received aPD-1 at the participating institutions. Objective response rate (ORR) was the primary outcome of interest and progression free survival (PFS) and overall survival were secondary outcomes. Univariate and multivariate analyses were conducted to assess association between clinicopathologic factors and outcomes, using logistic regression models. Results: A total of 36 pts were identified: 20 pts were treated with pembrolizumab and 16 with nivolumab. Median age was 50 (15-74). Twenty-nine (81%) were male. Twenty pts (56%) were Asian. Twenty-nine pts (81%) had EBV positive disease. Nine (25%) had aPD-1 as first-line therapy (1L). Molecular profiling results were available in 16 pts: TP53 mutation was the most common alteration (25%) and was limited to EBV negative tumors. Median total mutational burden (TMB) was 3/Mb (1-28). Median PD-L1 expression was 10% (0-90). Median follow up was 13.9 months (mos). Objective response was evaluable in all 36 pts: 9 pts achieved objective response (ORR 25.0%, 95% CI 12.1-42.2) with 2 complete responses: EBV positive vs. negative (27.6% vs. 14.2%, P=0.472), Asian vs. non-Asian (25% vs. 25%, P=1.000), and 1L vs. >1L (33.3% vs. 22.2%, P=0.511). Thirteen pts had stable disease (disease control rate 61.1%). Responses were seen in both TMB high (28/Mb) and low (1/Mb) tumors and no association with PD-L1 expression was observed. One-year survival rate was 81.3%. EBV positive pts had a trend towards better survival (84.8 vs. 66.7, P=0.640). Median PFS was 5.5 mos and not different between EBV positive vs. negative pts (5.6 vs. 4.0 mos, P=0.919). Conclusions: Our multi-institutional real-world experience with checkpoint inhibitor therapy in R/M NPC confirms that a similar degree of activity is seen as reported in the phase I-II experience in diverse races, but efficacy seems more prominent in EBV positive disease.