Pune, India | October 07, 2025
The U.S. Food and Drug Administration (FDA) has officially approved a new maintenance therapy for adults with extensive-stage small cell lung cancer (ES-SCLC). This involves the combination of lurbinectedin (Zepzelca) with either atezolizumab (Tecentriq) or its subcutaneous version, atezolizumab and hyaluronidase-tqjs (Tecentriq Hybryza). Specifically, the treatment applies to patients whose cancer has not progressed after receiving initial induction therapy using atezolizumab, carboplatin, and etoposide.
This recent FDA decision represents a crucial advancement in managing a particularly aggressive and fast-moving form of lung cancer. Historically, ES-SCLC treatment options beyond first-line chemotherapy have been extremely limited, with frequent relapses observed. Now, by introducing a maintenance therapy aimed at prolonging remission, this new approval offers a valuable alternative to both patients and oncology professionals.
The FDA based its approval largely on the IMforte clinical trial—a randomized, open-label, multicenter Phase 3 study. The trial enrolled 483 individuals with ES-SCLC who had completed four cycles of initial induction treatment. These patients were then randomized into two groups: one received the lurbinectedin and atezolizumab combination, while the other received atezolizumab alone. Treatment continued until the disease progressed or patients experienced unacceptable toxicity levels.
Importantly, the results revealed a significant improvement in median overall survival (OS) in the combination therapy group. Patients in this group lived an average of 13.2 months, compared to 10.6 months for those who received atezolizumab alone. Similarly, progression-free survival (PFS)—the time during which the cancer did not worsen—was extended to 5.4 months in the combination group, while the monotherapy group saw just 2.1 months.
These results were both statistically and clinically significant. The overall survival hazard ratio was 0.73, and the progression-free survival hazard ratio was 0.54. Furthermore, the p-values—0.0174 for OS and less than 0.0001 for PFS—highlight that the outcomes are highly unlikely to be due to random chance.
However, despite the clear benefits, these therapies also present notable safety concerns. Lurbinectedin has been linked to several serious adverse effects, including myelosuppression, liver toxicity, tissue damage at infusion sites, rhabdomyolysis, and risks to unborn children. Meanwhile, atezolizumab and its subcutaneous formulation may lead to severe immune-related reactions, complications during infusion, and adverse outcomes in bone marrow transplant recipients. Consequently, medical professionals must closely monitor patients throughout treatment and provide thorough education on possible side effects.
The approved dosing schedules are as follows: lurbinectedin is administered as a 3.2 mg/m² intravenous infusion every 21 days. Atezolizumab can be given every two, three, or four weeks, depending on the specific dose. In its subcutaneous form with hyaluronidase-tqjs, atezolizumab is delivered at 1875 mg with 30,000 units of hyaluronidase every three weeks.
This FDA approval was made possible under Project Orbis, a collaborative international review framework that accelerates access to promising cancer therapies. For this particular review, the FDA partnered with regulatory agencies in countries including Australia, Canada, Israel, and Switzerland. By working together, these agencies aim to speed up the global availability of critical treatments, especially for hard-to-treat conditions like ES-SCLC.
Additionally, both lurbinectedin and atezolizumab were granted orphan drug designation, which acknowledges their potential in treating rare and life-threatening diseases. The review process also received priority status and utilized the FDA’s Assessment Aid tool, which helps streamline regulatory decisions by presenting essential data in a consistent format.
For individuals living with ES-SCLC, any increase in survival time—even by a few months—can have a significant impact. Although the gains may appear modest at first glance, they are meaningful in the context of a disease with such limited post-chemotherapy options. Moreover, patients receiving the combination therapy in the IMforte trial not only lived longer but also experienced a longer period without disease progression, potentially improving their quality of life.
Nevertheless, physicians must carefully weigh the benefits of this therapy against its potential risks. Since not every patient will tolerate these drugs equally, appropriate patient selection becomes critical to achieving the best possible outcomes. Moreover, continued safety surveillance will be essential as more patients begin to receive this treatment in real-world settings.
Ultimately, this FDA decision marks a hopeful turning point in the ES-SCLC treatment landscape. For years, maintenance therapy following induction treatment remained largely stagnant. With this newly approved combination regimen, both patients and healthcare providers have access to an improved standard of care. As further clinical data becomes available, researchers may better define which patient populations are most likely to benefit.
Healthcare providers are strongly encouraged to report any serious adverse reactions through the FDA’s MedWatch program. Doing so will help ensure ongoing safety monitoring and contribute to optimizing patient care as this therapy becomes more widely adopted.
