Real-world comparative effectiveness of atezolizumab versus durvalumab for extensive-stage small-cell lung cancer.

[BACKGROUND] Both atezolizumab and durvalumab combined with platinum-etoposide have become standard first-line treatments for extensive-stage small-cell lung cancer (ES-SCLC), yet head-to-head real-world comparative data remain scarce.

[METHODS] We conducted a multicenter retrospective cohort study of 234 patients with ES-SCLC treated with atezolizumab plus platinum-etoposide (AEP; n = 126) or durvalumab plus platinum-etoposide (DEP; n = 108) across five Japanese institutions between 2016 and 2023. Progression-free survival (PFS) and overall survival (OS) were compared using Kaplan-Meier and overlap-weighted Cox models. Safety, a cost-effectiveness (cost-minimization) analysis based on restricted mean survival time-derived quality-adjusted life years (QALYs), and second-line treatment outcomes were also evaluated.

[RESULTS] Median PFS was 5.0 months for AEP and 5.1 months for DEP (hazard ratio [HR] 0.96; 95% CI, 0.73-1.26), and median OS was 12.0 and 12.1 months for AEP and DEP, respectively (HR 0.94; 95% CI, 0.68-1.31). Safety profiles were broadly equivalent between groups. Economic analysis showed nearly identical QALYs (1.002 vs 1.011) but lower total direct medical cost for AEP (¥4.14 million vs ¥4.88 million). Among 128 patients receiving second-line chemotherapy, those with platinum-sensitive relapse had significantly longer OS than those with platinum-refractory relapse, regardless of regimen.

[CONCLUSIONS] In real-world practice, AEP and DEP demonstrated equivalent efficacy and safety as first-line treatment for ES-SCLC. Given its lower cost with comparable QALYs, AEP may represent the more cost-minimizing option. The prognostic distinction between sensitive and refractory relapse remains clinically relevant after chemoimmunotherapy.