Durvalumab outcomes for patients with PD-L1 positive and negative stage III unresectable non-small cell lung cancer treated at veterans health administration facilities.

Abstract

e18793 Background: Clinical trials and real-world studies have documented the benefit of durvalumab consolidation therapy in patients with stage III unresectable non-small cell lung cancer (UR-NSCLC) following chemoradiotherapy (CRT). Methods: Patients with stage III UR-NSCLC on durvalumab following CRT, at any Veterans Health Administration (VHA) facility from 1/1/17 to 6/30/20, were included. Patients were followed from their durvalumab initiation date through the earliest of their last VHA visit, loss to follow up, death, or end of study. Electronic health record and chart review data were retrospectively collected to determine baseline characteristics, number of durvalumab doses, length of follow-up, and overall survival (OS). Chi-square and Wilcoxon rank sum tests were used to compare baseline characteristics for patients with PD-L1 negative (<1%) and positive (1% or greater) tumors. Kaplan-Meier curves were constructed for OS. Cox proportional hazards regression, with controls for divergent baseline characteristics, were used to compare OS between the two groups. Results: Of 935 available patients, 340 had PD-L1 results: 221 had PD-L1 positive (65%) and 119 had PD-L1 negative (35%) tumors. The two groups of patients were largely similar with respect to baseline characteristics, including age, sex at birth, White race, smoking status, marital status, Charlson Comorbidity Index, ECOG status, histology, stage, EGFR, and RAS mutations (Table). Patients with PD-L1 positive and negative tumors had a similar median (interquartile range [IQR]) number of durvalumab doses (15 [6-24] vs 12 [5-23], p=0.38) and length of follow-up (31.5 [12.1-43.5] vs 28.7 [12.2-40.6] months, p=0.43). Kaplan-Meier survival curves were similar for patients with PD-L1 positive and negative tumors: estimated 12-month OS rates (95% CI) of 84% (78%-88%) vs 89% (81%-93%) and 24-month OS rates of 72% (65%-78%) vs 76% (67%-84%); median OS was not reached in patients with PD-L1 positive tumors and was 47.0 months for the PD-L1 negative group. Cox Proportional Hazards regression analysis also demonstrated similar OS for both groups (p=0.64). Conclusions: In this real-world study of a subpopulation of VHA patients with stage III UR-NSCLC and known PD-L1 levels, survival benefits with durvalumab were consistent with those reported in the PACIFIC trial, despite having worse baseline prognostic factors. Patients with PD-L1 positive and negative tumors experienced similar overall survival, including 12- and 24-month OS rates.[Table: see text]