Pembrolizumab (Pem) For Advanced Non-Small Cell Lung Cancer (Ansclc): Efficacy And Safety In Everyday Clinical Practice.

e20506 Background: In clinical trials, Pem improves overall survival (OS) compared to chemotherapy in a subset of patients (pts) with aNSCLC. Immune related adverse events (irAE) have correlated with improved OS in some studies. We explored efficacy and safety of Pem in a provincial population. Methods: aNSCLC pts treated with Pem between 06/2015 and 08/2018 at BC Cancer were retrospectively identified. Kaplan-Meier curves of OS from initiation of Pem were plotted and multivariable analysis (MVA) was performed with Cox proportional hazard regression models. 3, 6, and 9 month landmark Kaplan-Meier analysis was performed and log-rank tests used to determine the association of irAE subtypes with OS. Multivariable logistic regression models for irAE within 3 months of Pem initiation were also fit. Results: Characteristics of the 190 pt cohort: median age 70y (41-91), ECOG PS 2/3 at start of Pem: 34.2%, squamous histology: 22.1%, EGFR mutation: 3.7%, brain (13.7%) or liver (8.9%) metastases, PD-L1 expression ≥ 50%: 92.6%, treatment line: 1st/ ≥2nd: 74.2%/25.8%. Median cycles delivered 7 (range 1-35). With median survival follow-up of 6.1 months (range 0.03-39.8 months) and 43% pts decreased, median OS of Pem in the 1st line and ≥2nd line settings were 24.3 months (95% CI, 9.7-not reached, NR) and 13.4 months (95% CI, 8.1-NR), respectively. Pts with ECOG PS 2/3 had lower OS vs. ECOG PS 0/1 (5.8 months vs. 16.7 months, log-rank p < 0.0001). On MVA, only ECOG PS (p < 0.001) was associated with OS. 66 pts (34.7% of cohort) experienced 89 irAE; most common irAE: dermatitis (20pts), hypothyroidism (13pts), and pneumonitis (10pts). 8.4% of cohort developed grade 3 or 4 irAE; no grade 5 irAE. The odds of a grade ≥ 3 irAE within 3 months was 6.3 fold higher if ECOG 2/3 vs. 0/1 (p = 0.05). A weak association between pneumonitis and decreased OS at 9 month landmark (p = 0.09) was seen; otherwise no association with irAE subtypes at 3, 6, and 9 month landmarks was observed. Conclusions: In the whole cohort, clinical efficacy and toxicity of Pem was consistent with registration trials. Pts with ECOG PS 2/3 had a significantly lower OS and higher odds of developing grade ≥ 3 irAE than those with good ECOG PS 0/1.