Merck & Co. Wins FDA Nod for Belzutifan-Lenvatinib in Kidney Cancer

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ONCOLOGY · ONCOLOGY APPROVAL · UNITED STATES

Two Food and Drug Administration approvals in fewer than four months have repositioned belzutifan (Welireg, Merck) from a late-line niche agent into a drug with a claim across multiple stages of clear cell renal cell carcinoma (ccRCC). On September 24, 2026, the FDA approved belzutifan in combination with lenvatinib (Lenvima, Eisai) for adults with advanced ccRCC following a programmed death receptor-1 (PD-1) or programmed death-ligand 1 (PD-L1) inhibitor, according to the agency’s approval notice. The decision follows a June 12, 2026 approval of belzutifan with pembrolizumab (Keytruda, Merck) in the adjuvant setting.

A Progression-Free Survival Win Without an Overall Survival Benefit

Efficacy for the September approval rests on LITESPARK-011 (NCT04586231), an open-label, randomized, active-controlled trial in 747 patients with advanced ccRCC that had progressed on or after a PD-1 or PD-L1 inhibitor, or within six months of completing adjuvant therapy with a PD-1 inhibitor, per the FDA’s approval notice. Patients were randomized 1:1 to belzutifan plus lenvatinib or to cabozantinib (Cabometyx, Exelixis), the current standard in this post-immunotherapy line.

Median progression-free survival (PFS) was 14.6 months (95% confidence interval [CI]: 11.1, 16.6) in the belzutifan-lenvatinib arm and 10.6 months (95% CI: 9.2, 11.1) in the cabozantinib arm, according to the FDA. The combination reduced the risk of disease progression or death by 26% (hazard ratio [HR] 0.74) compared with cabozantinib, according to Merck. The LITESPARK-011 data were first presented at the 2026 American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium, according to Fierce Pharma.

“With this FDA approval of belzutifan plus lenvatinib, we have a new treatment option for patients who progress following treatment with anti-PD-1/PD-L1 therapy.”

Robert Motzer, Memorial Sloan Kettering Cancer Center, in Merck’s announcement

The PFS result is statistically significant, but the final analysis of overall survival (OS) was not statistically significant, per the FDA’s approval notice. Median OS was 33.7 months in the belzutifan-lenvatinib arm and 28.6 months in the cabozantinib arm, according to the FDA.

That result matters for formulary positioning. Cabozantinib, the named comparator, retains an established evidence base; payers and oncology pharmacy and therapeutics committees evaluating preferred-tier status will weigh a PFS advantage against the lack of a statistically significant OS benefit at final analysis.

The June Adjuvant Approval and the Limits of the First-Line Attempt

The June 12 adjuvant approval, based on LITESPARK-022 (NCT05239728), enrolled 1,841 patients with prior nephrectomy for ccRCC at intermediate-high or high risk of recurrence, per the FDA. At a prespecified interim analysis, belzutifan plus pembrolizumab reduced the risk of disease recurrence, metastasis, or death by 28% relative to placebo plus pembrolizumab — an HR of 0.72 (95% CI: 0.59, 0.87; p-value 0.0003), according to the FDA.

The estimated disease-free survival (DFS) rate was 81% for the treatment arm versus 74% for the placebo arm, according to Fierce Pharma’s reporting. Median DFS was not reached in either arm, and OS data were not mature at the interim analysis, per the FDA. Toni Choueiri, the lead study author from the Dana-Farber Cancer Institute, described LITESPARK-022 as “the first adjuvant trial in kidney cancer to show a benefit for a combo versus a PD-1 agent alone,” according to Fierce Pharma.

The adjuvant and second-line wins, however, sit alongside a notable failure. Belzutifan did not improve PFS or OS when added to pembrolizumab and lenvatinib as first-line treatment for advanced ccRCC in the phase 3 LITESPARK-012 trial, Merck disclosed in April 2026, according to Fierce Pharma. That negative result, from a prespecified interim analysis, removes the largest potential patient pool from belzutifan’s addressable market.

Payer and Competitive Positioning

For payers, the September approval creates an immediate formulary obligation. Belzutifan plus lenvatinib now competes directly with cabozantinib in the post-checkpoint second-line ccRCC setting — a line where cabozantinib has been an established option. The combination introduces Eisai as a second commercial partner alongside Merck, which may affect contracting dynamics and rebate structures.

Two genitourinary cancer experts that Leerink Partners spoke with expressed reservations about the belzutifan-lenvatinib regimen specifically because of its lenvatinib component, according to Fierce Pharma’s April 2026 reporting. That expert hesitation, combined with the lack of a statistically significant OS benefit in LITESPARK-011, suggests the combination may face adoption friction in centers where cabozantinib is already embedded in clinical pathways.

Belzutifan’s original approval came in August 2021 for von Hippel-Lindau (VHL) disease, a rare hereditary condition. A December 2023 supplemental approval added the advanced ccRCC monotherapy indication following a PD-1 or PD-L1 inhibitor and a vascular endothelial growth factor tyrosine kinase inhibitor (VEGF-TKI), per FDA approval records. The September 2026 combination approval moves the drug one line earlier in the post-immunotherapy sequence — patients need only prior checkpoint inhibitor exposure, not prior TKI exposure, to be eligible. The prescribing information carries a boxed warning for embryo-fetal toxicity and warnings for anemia and hypoxia, per the current label published by the FDA.

The deeper structural point is that belzutifan’s 2026 regulatory record now spans two distinct clinical moments in ccRCC — post-surgery risk reduction and post-checkpoint progression — while the first-line door remains closed. That asymmetry, a drug present at the beginning and the middle of the disease course but absent from its most commercially dense entry point, is an unusual commercial profile that payers and oncologists will need to navigate simultaneously as formulary cycles open.

Belzutifan Regulatory Timeline and Clinical Data

Why this is relevant

Sources: FDA: FDA approves belzutifan in combination with lenvatinib for advanced renal cell carcinoma with a clear cell component · FDA: FDA approves belzutifan with pembrolizumab for adjuvant treatment of renal cell carcinoma · Merck: U.S. FDA Approves WELIREG (belzutifan) Plus LENVIMA (lenvatinib) · Fierce Pharma: A new standard? Merck’s Welireg combos deliver 1-2 punch to kidney cancer · Fierce Pharma: In a Merck Litespark shocker, Welireg triplet misses the mark in first-line kidney cancer · Fierce Pharma: Merck’s Welireg-Keytruda pairing sticks the landing in adjuvant kidney cancer treatment