FIRST-LINE maintenance treatment with lurbinectedin and atezolizumab significantly improves survival outcomes in patients with extensive-stage small cell lung cancer (ES-SCLC), according to primary results from the global Phase III IMforte trial presented at ASCO 2025.
The randomized, open-label study evaluated the efficacy of lurbinectedin plus atezolizumab compared to atezolizumab alone following standard induction therapy. A total of 660 treatment-naive patients with ES-SCLC received four 21-day cycles of atezolizumab, carboplatin, and etoposide. Among patients who did not experience disease progression after induction, 483 were randomized to receive maintenance therapy with either lurbinectedin plus atezolizumab or atezolizumab alone.
After a median follow-up of 15.0 months, the combination therapy demonstrated statistically significant improvements in both progression-free survival (PFS) and overall survival (OS). Median PFS in the lurbinectedin plus atezolizumab group was 5.4 months compared to 2.1 months in the monotherapy group (HR 0.54; 95% CI: 0.43–0.67; P<0.0001). Median OS was also improved, with patients receiving the combination therapy living a median of 13.2 months versus 10.6 months with atezolizumab alone (HR 0.73; 95% CI: 0.57–0.95; P=0.0174). While efficacy outcomes favored the combination, safety data revealed higher rates of treatment-related adverse events (TRAEs). Grade 3/4 TRAEs occurred in 25.6% of patients in the lurbinectedin plus atezolizumab group compared to 5.8% in the atezolizumab monotherapy group. Serious adverse events, including sepsis and febrile neutropenia, led to treatment discontinuation in 6.2% and 3.3% of patients, respectively. IMforte is the first global Phase 3 trial to show both PFS and OS benefit with first-line maintenance therapy in ES-SCLC. Investigators report that the lurbinectedin-atezolizumab combination was generally well tolerated and did not introduce any new or unexpected safety signals. These findings establish lurbinectedin plus atezolizumab as a potential new standard of care in the maintenance setting for patients with this aggressive lung cancer subtype, offering a meaningful advancement in a historically difficult-to-treat population. Reference: Paz-Ares et al. ASCO 2025. Lurbinectedin (lurbi) + atezolizumab (atezo) as first-line (1L) maintenance treatment (tx) in patients (pts) with extensive-stage small cell lung cancer (ES-SCLC): Primary results of the phase 3 IMforte trial. May 21, 2025. Available at: https://www.asco.org/abstracts-presentations/ABSTRACT505814. Last accessed: May 31, 2025. [Press release].
