Sweden-based biopharma Immedica revealed that lurbinectedin (Zepzelca) combined with atezolizumab has received a positive opinion from the European Medicines Agency's Committee for Medicinal Products for Human Use (CHMP) as first-line maintenance therapy for extensive-stage small cell lung cancer, moving the combination closer to becoming the first approved regimen to improve survival beyond checkpoint inhibitor monotherapy in this setting.
The opinion is based on data from the Phase III IMforte trial, a randomized, open-label study enrolling adults with ES-SCLC whose disease had not progressed following four cycles of induction therapy with atezolizumab, carboplatin, and etoposide.
In IMforte, the lurbinectedin-atezolizumab combination reduced the risk of disease progression or death by 46% and the risk of death by 27% compared with atezolizumab maintenance alone. Measured from the point of randomization, median overall survival was 13.2 months versus 10.6 months (HR 0.73; 95% CI: 0.57–0.95; p=0.0174), and median progression-free survival by independent assessment was 5.4 months versus 2.1 months (HR 0.54; 95% CI: 0.43–0.67; p<0.0001). The data were presented at the 2025 ASCO annual meeting and published simultaneously in The Lancet. Safety was consistent with the known profiles of both agents.
The CHMP opinion now passes to the European Commission for a final marketing authorization decision covering the EU.
The decision context
Before the FDA approved lurbinectedin plus atezolizumab in October 2025, the maintenance phase of ES-SCLC treatment was defined by continuation of a single checkpoint inhibitor — Roche's PD-L1 target datezolizumab (Tecentriq) following the IMpower133 regimen, or AstraZeneca's PD-L1 durvalumab (Imfinzi) following the CASPIAN regimen. Both approaches offered modest survival benefit over chemotherapy alone but left the maintenance window largely unchallenged. The IMforte control arm, with a median PFS of 2.1 months on atezolizumab alone, illustrates how quickly patients progressed even after responding to induction.
Lurbinectedin is a marine-derived small molecule that inhibits RNA polymerase II-dependent transcription, suppressing oncogenic transcription programs in tumor cells and, according to PharmaMar's characterization, also downregulating cytokine production in tumor-associated macrophages. The mechanistic rationale for pairing it with a PD-L1 inhibitor rests on the premise that transcription inhibition and immune checkpoint blockade address distinct and potentially complementary tumor escape mechanisms. Whether this dual targeting accounts for the observed survival benefit, or whether the cytotoxic activity of lurbinectedin is the primary driver, is not established from the press release data alone.
The survival gain — approximately 2.6 months in median OS and 3.3 months in median PFS — is statistically significant and consistent across both endpoints, which strengthens the signal. The OS hazard ratio of 0.73, however, sits at the wider end of what oncologists typically consider a practice-defining benefit in a maintenance setting, and the confidence interval (0.57–0.95) approaches 1.0. The PFS benefit is more pronounced (HR 0.54), but PFS improvements in SCLC have not always translated proportionally to OS gains, and the absolute OS difference here is modest.
The competitive framing is also shifting. Tarlatamab, a DLL3×CD3 T-cell engager developed by Amgen, is in Phase III evaluation in relapsed SCLC benchmarked against standard-of-care chemotherapy options that include lurbinectedin. That program operates in a different line of therapy and uses a mechanistically distinct approach — immune redirection rather than transcription inhibition — but it signals that the SCLC treatment landscape is being contested across multiple modalities simultaneously. Cross-trial comparisons are limited by differences in patient populations, lines of therapy, and trial design, and no head-to-head data exist between these approaches in any shared setting.
For Immedica, the CHMP opinion covers its distribution territories in the Nordics, UK and Ireland, Central and Eastern Europe, and the Middle East and North Africa, under a partnership with PharmaMar, which originated the compound. Jazz Pharmaceuticals holds US rights and sponsored the FDA approval. The commercial structure means that the EU authorization, once granted by the European Commission, will be executed across multiple regional partners rather than a single entity — a distribution model that may affect how quickly the combination reaches patients in different healthcare systems.
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