Jazz and PharmaMar's Zepzelca Fails Phase 3 LAGOON Confirmatory Trial in Second-Line Small Cell Lung Cancer
On June 12, 2026, Jazz Pharmaceuticals and PharmaMar announced that the Phase 3 LAGOON confirmatory trial for Zepzelca (lurbinectedin) in patients with relapsed (second-line) metastatic small cell lung cancer (SCLC) failed to meet its primary endpoint of overall survival (OS). The trial evaluated Zepzelca either as a monotherapy or in combination with irinotecan versus investigator's choice of chemotherapy (topotecan or irinotecan).
The trial results revealed a disappointing performance for Zepzelca monotherapy, which actually showed a detriment in survival compared to the control group. Patients receiving Zepzelca monotherapy experienced a median overall survival of 8.7 months, compared to 10.7 months for the control arm, representing a 19% higher risk of death. The combination of Zepzelca and irinotecan demonstrated a marginal, non-statistically significant 9.8% improvement in OS (median OS of 11.1 months for the combination vs. 10.7 months for control in patients without CNS metastases).
This failure represents a severe blow to Zepzelca's second-line SCLC franchise. The drug received FDA accelerated approval in 2020 based on tumor shrinkage data from a Phase 2 single-arm trial. Since then, an initial confirmatory Phase 3 trial (ATLANTIS) failed to show an overall survival benefit for a Zepzelca-doxorubicin combination. Although the FDA permitted Zepzelca to remain on the market due to dosing differences in ATLANTIS and a high unmet medical need, this second confirmatory failure at the approved monotherapy dose puts the second-line indication in serious jeopardy.1
Importantly, this failure does not affect Zepzelca's full FDA approval granted in 2025 as a first-line maintenance therapy in extensive-stage SCLC in combination with Roche's Tecentriq (based on the successful Phase 3 IMforte trial). However, commercially, Zepzelca's second-line market share is already declining due to the launch of Amgen's T-cell engager Imdelltra. Jazz reported $101 million in Zepzelca sales for Q1 2026, driven by first-line maintenance uptake but offset by a decline in second-line use. Jazz stated that it has shared the LAGOON results with the FDA and will discuss the clinical and regulatory path forward.
Verbatim Quotes
- "According to Jazz, Zepzelca monotherapy performed even worse than the control arm, with a 19% higher risk of death. Patients who got Zepzelca alone lived a median 8.7 months, versus 10.7 months for those in the control arm." — Fierce Pharma
- "Zepzelca-irinotecan showed a numerical, but marginal, overall survival benefit with a 9.8% improvement, which didn’t meet statistical significance, according to Jazz." — Fierce Pharma
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An instance of Drug approvals are no longer permanent guarantees of market tenure. — A second consecutive clinical failure in post-marketing confirmatory trials has placed Zepzelca's accelerated FDA approval under imminent threat of revocation. ↩︎