Efficacy of nivolumab + ipilimumab ± chemotherapy versus pembrolizumab + chemotherapy in patients with PD-L1-negative non-small cell lung cancer (START001 PART-B): a multicenter retrospective observational study.

Background: Programmed death ligand 1 (PD-L1) serves as a crucial biomarker for predicting the efficacy of immune checkpoint inhibitors in patients with non-small cell lung cancer (NSCLC). This study aimed to identify the most suitable first-line treatment regimen for patients with PD-L1 expression <1% (PD-L1-negative) NSCLC by comparing nivolumab plus ipilimumab (NI), NI combined with chemotherapy (NICT), and pembrolizumab and chemotherapy (PCT).

Methods: We analyzed data from 141 patients with PD-L1-negative NSCLC treated with NI, NICT, or PCT at 14 Japanese institutions between December 2020 and November 2022. Propensity score analysis was employed to minimize selection bias, and Kaplan-Meier analysis and Cox proportional hazards regression were used to evaluate progression-free survival (PFS) and overall survival (OS).

Results: Neither NI nor NICT demonstrated superior PFS or OS than PCT. Subgroup analyses revealed no significant differences between treatment groups across age, histological subtypes, or clinical features. Results from propensity score matching and inverse probability of treatment weighting were consistent with those observed in the overall cohort. Moreover, safety profiles showed that PCT was associated with the lowest rates of treatment discontinuation and immune-related adverse events requiring systemic corticosteroid therapy.

Conclusions: In patients with PD-L1-negative NSCLC, the efficacy of NI and NICT was not superior to that of PCT. Thus, we concluded that PCT could be a favorable treatment option for this patient population.