Results from the phase 3 IMforte trial demonstrated that lurbinectedin plus atezolizumab improved survival outcomes compared to atezolizumab alone among patients with extensive-stage small cell lung cancer (ES-SCLC) in the first-line maintenance setting. 

These data were first presented by Luis Paz-Ares, MD, PhD, Hospital Universitario 12 de Octubre, Universidad Complutense and Ciberonc, Madrid, Spain, at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois. 

In this study, researchers enrolled 483 treatment-naive patients to receive 4 cycles of induction treatment with atezolizumab plus carboplatin and etoposide in 21-day cycles. Following induction treatment, patients were randomized on a 1-to-1 basis to receive maintenance therapy of 1200 mg of atezolizumab either alone (n = 241) or in combination with 3.2 mg/m² of lurbinectedin (n = 242) until disease progression or unacceptable toxicity. Patients were stratified based on presence of liver metastases, prophylactic cranial irradiation, performance status, and lactate dehydrogenase level. Primary end points included progression-free survival (PFS) and overall survival (OS). A key secondary end point was safety. 

At a median follow-up of 15 months, median PFS was 5.4 months in the lurbinectedin plus atezolizumab arm and 2.1 months in the atezolizumab arm (hazard ratio [HR] 0.54; 95% confidence interval [CI], 0.43 to 0.67; P < .0001). Median OS was 13.2 months and 10.6 months (HR 0.73; 95% CI, 0.57 to 0.95; P = .0174), respectively. Grade 3/4 treatment-related adverse events occurred in 25.6% of patients in the lurbinectedin plus atezolizumab arm and 5.8% of patients in the atezolizumab arm. Grade 5 treatment-related adverse events were reported in 2 patients in the lurbinectedin plus atezolizumab arm and 1 patient in the atezolizumab arm. Adverse events led to treatment discontinuation in 6.2% and 3.3% of patients, respectively.

“IMforte is the first global phase 3 study to show PFS and OS improvement with [first line] maintenance [treatment] for ES-SCLC and supports maintenance [lurbinectedin plus atezolizumab] as a new option for [patients] with this aggressive disease,” concluded Dr Paz-Ares et al. 

Source: 

Paz-Ares L, Borghaei H, Liu S, et al. 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. Presented at 2025 ASCO Annual Meeting. May 30-June 3, 2025; Chicago, IL. Abstract 8006