Merck Gains FDA Approval For Kidney Cancer Drug Combination

Manufacturers holding combination oncology portfolios now face a concrete labeling precedent: Merck's Welireg (belzutifan) received FDA approval on September 24, 2026, in combination with Eisai's Lenvima (lenvatinib), for adults with advanced renal cell carcinoma with a clear cell component (ccRCC) whose disease progressed on or after a PD-1 or PD-L1 inhibitor. The approval introduces a dual-product prescribing information structure carrying a boxed warning for embryo-fetal toxicity on the belzutifan label, with cardiac dysfunction warnings added specifically for the combination, a labeling architecture that QA and regulatory affairs teams managing multi-sponsor products will need to track closely.

Efficacy data came from LITESPARK-011 (NCT04586231), an open-label, randomized, active-controlled trial enrolling 747 patients with advanced ccRCC. Patients were randomized 1:1 to belzutifan plus lenvatinib or cabozantinib. The primary endpoint of progression-free survival, assessed by blinded independent central review using RECIST v1.1, showed a statistically significant improvement: median PFS of 14.6 months versus 10.6 months for cabozantinib (HR 0.74 [95% CI: 0.61, 0.89]; p=0.00095). Objective response rate reached 53% versus 40% (p=0.0002). The final overall survival analysis did not reach statistical significance, with median OS of 33.7 months versus 28.6 months (HR 0.85 [95% CI: 0.70, 1.03]).

The recommended dosage is 120 mg belzutifan and 20 mg lenvatinib once daily until disease progression or unacceptable toxicity. Beyond the boxed warning, the belzutifan label carries precautions for anemia and hypoxia; the lenvatinib label extends to hypertension, hepatotoxicity, renal impairment, QT prolongation, arterial thromboembolic events, and more than a dozen additional warnings. For regulatory affairs leads coordinating prescribing information across two separate NDA holders, reconciling these warning profiles within a single combination-use context represents a non-trivial documentation exercise under 21 CFR Part 201 labeling requirements.

This review also used the Assessment Aid, a voluntary applicant submission tool designed to structure and accelerate FDA's review process. Its use here signals continued agency interest in the tool for complex oncology applications, and sponsors preparing submissions in comparable combination settings may find it relevant to their pre-submission strategy discussions with review divisions.

Full prescribing information for both Welireg and Lenvima will be posted to Drugs@FDA, where regulatory teams can access the final labeling for both products and benchmark combination-specific warning language against their own development programs.