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FDA Expands Merck's Welireg Label for a New Kidney Cancer Indication

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Key Takeaways

  • Merck's Welireg plus Lenvima wins FDA approval for certain previously treated advanced ccRCC patients.
  • The regimen cut disease progression or death risk by 26% in the phase III LITESPARK-011 study.
  • Welireg sales rose 57% year over year to $470 million in the first half of 2026.

Merck (MRK - Free Report) announced that the FDA has expanded the label of its oral cancer drug Welireg (belzutifan) for a third indication in advanced renal cell carcinoma (RCC), the most common type of adult kidney cancer.

The drug has been approved in combination with Eisai’s blockbuster cancer drug Lenvima (lenvatinib) to treat adult patients with advanced RCC with a clear cell component (ccRCC) following a PD-1/PD-L1 inhibitor.

The approval is supported by data from the phase III LITESPARK-011 study, which evaluated the combination therapy against Exelixis’ (EXEL) blockbuster drug Cabometyx (cabozantinib). The study achieved one of its dual primary endpoints of progression-free survival. Data showed that the regimen reduced the risk of disease progression or death by 26%. Though the combination did not meet the other primary endpoint of overall survival (OS), it showed a trend toward improvement.

MRK’s Stock Performance

The company’s shares have risen 41% year to date compared with the industry’s 13% growth.

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Welireg Growth Provides a Catalyst for Merck

The latest approval comes as the drug’s sales are already expanding rapidly. Merck reported $470 million from Welireg sales in the first half of 2026, up 57% year over year, driven by higher demand in the United States and continued launch uptake in international markets.

The new indication could further expand Welireg’s addressable patient population in advanced ccRCC, particularly as it moves the drug into another treatment setting following PD-1/PD-L1 therapy. It also gives Merck another treatment option in a market where Cabometyx is an established therapy.

Welireg is already approved for two other ccRCC indications. As a monotherapy, it is approved for certain patients with advanced ccRCC following treatment with both a PD-1/PD-L1 inhibitor and a VEGF-TKI. It is also approved in combination with Merck’s blockbuster cancer drug Keytruda for the adjuvant treatment of adults with ccRCC at intermediate-high or high risk of recurrence following nephrectomy, with or without resection of metastatic lesions.

The drug is also approved for certain adult patients with von Hippel-Lindau, a rare inherited disorder that can cause tumors to develop in multiple organs. It is also approved to treat patients aged 12 years and older with locally advanced, unresectable or metastatic pheochromocytoma or paraganglioma, rare tumors that arise in hormone-producing tissues that can produce excess hormones.

Merck is also evaluating Welireg as part of a broader clinical program in RCC and selected solid tumors across different treatment settings.

MRK’s Zacks Rank

Merck currently carries a Zacks Rank #3 (Hold).

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