Luis G. Paz-Ares, MD, PhD, took the stage on Monday, June 2, at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting to present findings from the phase III IMforte trial, which evaluated lurbinectedin in combination with atezolizumab as maintenance therapy for patients with extensive-stage small cell lung cancer (ES-SCLC). Dr. Paz-Arez, the study’s lead author, said the latest data indicate that some patients experienced improved survival outcomes with the lurbinectedin-atezolizumab combination compared with atezolizumab alone.
Small cell lung cancer (SCLC) is among the most aggressive and difficult-to-treat forms of cancer, even with improved outcomes observed after first-line immunotherapy. It represents between 13% to 15% of lung cancer cases, and nearly three-quarters (70%) of patients are diagnosed after their SCLC has already progressed to the extensive stage.1
With a 5-year relative survival rate of only 3% and a median survival of 1 year, there is an urgent need for alternative treatment strategies.1
“This IMforte outcome represents a major milestone and could provide a much-needed option for advancing the treatment of this aggressive disease,” said Dr. Paz-Ares, Professor of Medicine at 12 de Octubre University Hospital in Madrid, Spain.
About the Trial
The randomized, open-label IMforte trial compared maintenance therapy with lurbinectedin plus atezolizumab to atezolizumab alone. The combination therapy followed first-line induction therapy with carboplatin, etoposide, and atezolizumab.2 The study was made up of two phases: induction and maintenance.
In the atezolizumab-lurbinectedin combination arm, participants in the induction phase received standard-of-care atezolizumab (day 1) in combination with carboplatin (day 1) and etoposide (days 1, 2, and 3) every 21 days for four cycles.2 Participants in the maintenance phase were administered atezolizumab in combination with lurbinectedin on day 1 of each 21-day cycle.2
In the atezolizumab-only arm, participants either received:
- Atezolizumab on day 1 of each 21-day cycle
- Atezolizumab (day 1) in combination with carboplatin (day 1) and etoposide (days 1, 2, and 3) of each 21-day cycle for four cycles2
The primary endpoints were independent review facility (IRF)-assessed progression-free survival (PFS) and overall survival (OS).2 Secondary outcome measures included:
- Investigator-assessed PFS
- Confirmed objective response rate (ORR)
- Duration of response (DOR)
- Participants with adverse events (AEs)2
Trial Results
The IMforte results demonstrated significant benefits for participants who received lurbinectedin plus atezolizumab compared with atezolizumab monotherapy. The median PFS was 5.4 months in participants treated with lurbinectedin plus atezolizumab versus 2.1 months with atezolizumab monotherapy.
In participants treated with the lurbinectedin-atezolizumab combination, the median OS was 13.2 months versus 10.6 months for those treated with atezolizumab alone.1 Additionally, participants treated with lurbinectedin plus atezolizumab had a 46% lower risk of disease progression and a 27% lower risk of death versus those treated with atezolizumab monotherapy.1
While the survival benefits were favorable for lurbinectedin plus atezolizumab, participants in the combination arm had more AEs compared with the atezolizumab-only arm:
- Treatment-related adverse events (TRAEs): 83.5% versus 40%
- Treatment discontinuation related to AEs: 6.2% versus 3.3%
- Grade 3 or 4 AEs: 25.6% versus 5.8%
- Grade 5 AEs: 0.8% versus 0.4%1
Future Directions
These latest results from the IMforte trial underscore the potential of the lurbinectedin-atezolizumab combination in the maintenance setting for ES-SCLC.
Though the research is ongoing, these data represent a promising step forward in improving both survival outcomes and disease control for one of the most difficult-to-treat cancers.
References
