DUBLIN, Ireland, June 12, 2026
Jazz Pharmaceuticals has announced topline results from the Phase 3 LAGOON trial evaluating Zepzelca® (lurbinectedin) as a second-line treatment for patients with relapsed metastatic small cell lung cancer (SCLC). While the study did not achieve its primary endpoint of overall survival (OS) when assessing Zepzelca either as monotherapy or in combination with irinotecan compared with investigator-selected chemotherapy, the findings provide important clinical insights into one of the most challenging and aggressive forms of lung cancer. Importantly, no new safety signals were identified, and the safety profile of Zepzelca remained consistent with previous clinical experience. The results underscore the ongoing complexity of treating relapsed SCLC while reinforcing Jazz Pharmaceuticals’ commitment to advancing innovative oncology therapies for patients with limited treatment options.
Phase 3 LAGOON Trial Misses Overall Survival Endpoint
The global Phase 3 LAGOON study, sponsored by PharmaMar and conducted in partnership with Jazz Pharmaceuticals, enrolled 724 patients across more than 200 clinical sites worldwide. The randomized, multicenter trial compared Zepzelca monotherapy, Zepzelca combined with irinotecan, and investigator-selected treatment with topotecan or irinotecan in patients whose disease progressed following platinum-based chemotherapy. Results showed median overall survival of 8.7 months for Zepzelca monotherapy, 10.9 months for the combination arm, and 10.7 months for the control group, indicating that the study did not meet the predefined statistical threshold for superiority.
Researchers noted that the trial included a broader patient population than earlier studies, including individuals with a history of central nervous system (CNS) metastases, which may have influenced outcomes. Despite the setback, the trial generated valuable clinical data that could help inform future treatment strategies for relapsed SCLC.
Safety Profile Remains Favorable Across Treatment Arms
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A key positive outcome from the LAGOON study was the maintenance of a favorable safety profile for Zepzelca. Treatment-related adverse events occurred in 78.5% of patients receiving Zepzelca monotherapy, compared with 93.8% in the control arm. Severe treatment-related adverse events classified as Grade 3 or higher were reported in 35% of patients treated with Zepzelca, significantly lower than the 64.4% observed in the control group. No unexpected safety concerns emerged during the study, supporting the established safety characteristics of the drug. These findings are particularly relevant for patients with relapsed SCLC, where maintaining quality of life and minimizing treatment burden remain critical considerations alongside efficacy outcomes.
Strong Position Maintained in First-Line Maintenance Therapy
Although the LAGOON trial did not achieve its primary objective in second-line SCLC, Jazz emphasized that the results do not affect the drug’s approved role in the first-line maintenance setting. In 2025, the U.S. FDA granted full approval to Zepzelca in combination with atezolizumab for maintenance treatment of adults with extensive-stage SCLC whose disease had not progressed following initial induction therapy. That approval was based on the successful Phase 3 IMforte trial, which demonstrated statistically significant improvements in both overall survival and progression-free survival. In the IMforte study, the combination reduced the risk of disease progression or death by 46% and lowered the risk of death by 27% compared with atezolizumab alone.
Jazz Pharmaceuticals has already shared the LAGOON findings with regulatory authorities and plans to discuss future steps regarding post-marketing commitments for the second-line indication. As the company continues expanding its oncology portfolio, Zepzelca remains an important component of its strategy to address unmet needs in aggressive lung cancers.
Source: Jazz Pharmaceuticals press release
