Treatment interruptions and discontinuations among patients with stage III unresectable non–small cell lung cancer treated with durvalumab at the Veterans Health Administration.

8554 Background: The PD-1/PD-L1 pathway is a mechanism of immune evasion and disruption of this pathway with immune checkpoint inhibitors (ICIs) has shown clinical benefit in multiple malignancies. Based on results from the PACIFIC trial, durvalumab is approved as consolidation therapy in patients (pts) with stage III unresectable non-small cell lung cancer (UR-NSCLC) without progression following concurrent chemoradiotherapy (cCRT). Durvalumab has been used extensively in Veterans Health Administration (VHA) facilities, providing an opportunity to evaluate durvalumab treatment interruptions (TI), treatment discontinuations (TD), and the reasons for these on a national scale. Methods: Patients with stage III UR-NSCLC receiving durvalumab consolidation immunotherapy at the VHA between January 1, 2017 and June 30, 2020 with a minimum follow up for 12 months were included using ICD-10, HCPCS, and J codes and followed from their durvalumab start date through the earliest of last VHA visit, loss to follow up, death, or end of study (excluded if durvalumab therapy was ongoing at the end of the study, because the full treatment course could not be determined). TI were defined as durvalumab infusions separated by >28 days. Reasons for TI and TD are presented descriptively. Durations are reported using medians and interquartile ranges (IQR). Results: 935 pts were included (median age = 69 years; 95% males; 96% current or former smokers; 70% with COPD; histologies [squamous (50%), non-squamous (43%), other/missing (7%)]; and 77% with carboplatin-paclitaxel as their platinum-based CRT). Durvalumab TI were experienced by 19% of pts (median [IQR] number of TI = 1 [1-1], median [IQR] TI duration = 53 days [39-90]). The main reasons for TI were toxicity (8%) and social reasons (3%) (Table). The median duration of treatment (DoT) with durvalumab (TI included) was 9.0 months (IQR 2.9-11.8). Durvalumab TD occurred in 59% of pts. Top reasons for discontinuation across all 935 pts included disease progression (24%) and toxicity (18%) (Table). Conclusions: In this real world analysis of national VHA data, durvalumab DoT was similar to PACIFIC despite having a patient population with worse prognostic factors (e.g. more males, squamous, COPD) with 8% of VHA pts experiencing TI and 18% TD due to toxicity. Patients could benefit from additional efforts to prevent, identify, and manage toxicities in the UR-NSCLC population [Table: see text]