Lurbinectedin/Atezolizumab Maintenance Improves Survival in ES-SCLC
Stephen V. Liu, MD, discusses the phase 3 IMforte study of lurbinectedin and atezolizumab in extended-stage small cell lung cancer.
In an interview with Targeted OncologyTM, Stephen V. Liu, MD, associate professor of medicine at Georgetown University, discusses the phase 3 IMforte study (NCT05091567), findings of which were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting.
IMforte investigated the efficacy and safety of first-line (1L) maintenance therapy with lurbinectedin (Zepzelca) plus atezolizumab (Tecentriq) versus atezolizumab alone in patients with extensive-stage small cell lung cancer (ES-SCLC). This study aimed to improve long-term survival, which remains limited despite initial improvements with 1L PD-(L)1 inhibitors and platinum-based chemotherapy.
The trial included patients with treatment-naive ES-SCLC who initially received 4 cycles of standard induction therapy with atezolizumab, carboplatin, and etoposide. Patients without disease progression were then randomized 1:1 to receive maintenance treatment with either lurbinectedin (3.2 mg/m2 IV with G-CSF prophylaxis) plus atezolizumab (1200 mg IV) or atezolizumab alone every 3 weeks until disease progression, unacceptable toxicity, or withdrawal.
Of 660 enrolled patients, 483 were randomized (242 to lurbinectedin/atezolizumab; 241 to atezolizumab). With a median follow-up of 15 months, the combination significantly improved independent review facility-assessed progression-free survival (PFS) compared to atezolizumab alone (stratified HR, 0.54; P <.0001). A significant overall survival (OS) benefit was also observed with the combination therapy (stratified HR, 0.73; P =.0174).
Regarding safety, treatment-related adverse events (TRAEs) were more frequent in the combination arm (83.5% vs 40.0%), as were grade 3/4 TRAEs (25.6% vs 5.8%). However, the combination was generally well tolerated, with no new or unexpected safety signals. Discontinuation due to TRAEs occurred in 6.2% of patients in the combination arm vs 3.3% in the atezolizumab arm.
The IMforte study successfully met both its primary end points, demonstrating a clinically meaningful improvement in both PFS and OS. These results suggest that 1L maintenance therapy with lurbinectedin plus atezolizumab represents a new and promising treatment option for patients with ES-SCLC.
