The association between immune-related adverse events and efficacy outcomes with consolidation pembrolizumab after chemoradiation in patients with stage III NSCLC: an analysis from HCRN LUN 14-179

9032 Background: Consolidation checkpoint inhibitor therapy (CPI) for up to 1 year following chemoradiation (CRT) is a current standard of care for pts with inoperable stage III NSCLC. However, some pts are not able to complete 1 year of CPI due to immune-related adverse events (irAES). In multiple retrospective studies, pts with stage IV NSCLC treated with CPI who experience irAEs generally receive fewer cycles of CPI without a significant detrimental effect on efficacy. The association between irAEs and outcomes with consolidation CPI after CRT has never been reported. Here we report the association between irAEs and efficacy outcomes from the HCRN LUN 14-179, a single-arm phase II trial of consolidation pembrolizumab following concurrent CRT in pts with unresectable stage III NSCLC. Methods: After completion of CRT eligible pts with stage III NSCLC without PD received pembrolizumab 200 mg IV q 3 wks for up to 1 yr. Demographics, disease characteristics, and number of cycles of pembrolizumab received were reported in pts who had any grade irAEs (except pneumonitis which included grade >2 only) [Group A] and those without irAEs (except grade 1 pneumonitis) [Group B]. Chi-square test (or Fisher's Exact test) were used for comparisons for categorical variables and Wilcoxon test for continuous variables. The Kaplan-Meier method was used to analyze time to metastatic disease (TMDD), PFS, and OS. A log-rank test was used to compare groups. Results: 92 eligible pts for efficacy analysis were enrolled from March 2015 to November 2016. 4 yr OS estimate for all pts is 46.2%. Any grade irAEs (except grade I pneumonitis) (n = 37 pts) included pneumonitis (18.5%), colitis (3.3%), increased creatinine (5.4%), elevated transaminases (3.3%), hyperthyroidism (7.6%), hypothyroidism (13.0%). Grade ≥ 2 irAEs (n = 32 pts) included pneumonitis (18.5%), hypothyroidism (10.8%), and colitis (3.3%). Group A/B: male (21/38), female (16/17), current or former smoker (35/52), stage IIIA (20/35), stage IIIB (17/20), non-squamous (21/30), squamous (16/25). Median number of pembrolizumab cycles received in Group A/B pts were 9 vs 15 (p = 0.0942) respectively. 4 yr efficacy endpoints in Groups A/B were TMDD 35.3% vs 41.3% (p = 0.83), PFS 27.8% vs 28.7% (p = 0.97), OS 43.5% vs 47.9% (p = 0.99), respectively. Conclusions: Despite receiving fewer cycles of consolidation pembrolizumab, pts who experienced any grade irAEs (excluding grade 1 pneumonitis) did not have significantly reduced efficacy outcomes. Clinical trial information: NCT02343952.