Atezolizumab vs durvalumab for extensive-stage small cell lung cancer in Japan: a real-world comparative analysis of costs and clinical outcomes.

BACKGROUND

Platinum-etoposide combined with a PD-L1 inhibitor (atezolizumab or durvalumab) is the standard first-line treatment for extensive-stage small cell lung cancer (ES-SCLC). Although phase 3 trials have demonstrated similar efficacy, no direct comparison exists, and differences in treatment cost and resource utilization may influence clinical decision-making.

METHODS

In this multicenter retrospective study, real-world data from eight Japanese institutions were analyzed. Patients with ES-SCLC treated with platinum-etoposide plus atezolizumab or durvalumab between August 2018 and December 2022 were included. Individual-level medical costs were calculated from health insurance claims linked to electronic medical records. After propensity score matching and exclusion of cisplatin-treated patients, 128 patients were analyzed. The primary outcome was mean monthly medical cost during immunotherapy. Secondary outcomes included overall survival (OS), immune-related adverse events (irAEs), and prognostic factors.

RESULTS

Among 128 patients (mean age, 74 years; 85% male), mean monthly medical cost was significantly lower with atezolizumab than durvalumab (¥1 003 922 [$7183] vs ¥1 596 511 [$11 422]; P < .001). Median OS was comparable (13.9 months [95% CI, 11.7-17.5] vs 14.8 months [95% CI, 10.5-not reached]; P = .92). Grade ≥2 irAEs (11% vs 31%; P = .009) and interstitial lung disease (3% vs 20%; P = .004) were less frequent with atezolizumab. Poor performance status was associated with worse OS, whereas treatment type was not.

CONCLUSIONS

Atezolizumab was associated with lower medical costs and similar survival outcomes compared with durvalumab in ES-SCLC, suggesting its use as a clinically comparable option with lower associated costs in Japanese real-world practice.