FDA Approves New Drug Combo for Advanced Kidney Cancer

On September 24, 2026, the US Food and Drug Administration approved a new two-drug regimen for adults with advanced clear-cell kidney cancer that has progressed after immunotherapy: belzutifan (Welireg), Merck's first-in-class oral HIF-2α inhibitor, paired with lenvatinib (Lenvima), Eisai's multi-receptor tyrosine kinase inhibitor. According to the FDA's announcement, the approval covers patients whose disease advanced on or after a PD-1 or PD-L1 inhibitor, including those whose cancer returned within six months of finishing adjuvant PD-1 therapy. The agency's approval notice is available here.

Kidney cancer that stops responding to immunotherapy leaves patients with a short list of options, and this decision adds a combination that works differently from what came before. Belzutifan blocks hypoxia-inducible factor-2 alpha, a protein that clear-cell tumours rely on to survive in low-oxygen conditions. Lenvatinib targets the receptors tumours use to grow new blood vessels. Merck described the pairing as the first approved regimen of its kind in a statement, combining a HIF-2α inhibitor with a tyrosine kinase inhibitor for this patient group.

The trial behind the approval

The decision rests on LITESPARK-011, an open-label phase 3 trial that enrolled 747 patients with advanced clear-cell renal cell carcinoma whose cancer had progressed on or after immunotherapy. Participants were randomly assigned to receive either the belzutifan–lenvatinib combination or cabozantinib, an established standard drug for this setting.

The combination delayed cancer progression by a median of 14.6 months, compared with 10.6 months on cabozantinib. That translates to a 26 percent reduction in the risk of progression or death, with a hazard ratio of 0.74 and a one-sided p value of 0.00095, according to the FDA's review of the trial data. More than half of the patients on the new pair saw their tumours shrink: the objective response rate was 53 percent, against 40 percent for cabozantinib, with a p value of 0.0002.

Overall survival, the trial's other primary endpoint, did not reach statistical significance in the final analysis. Median overall survival was 33.7 months with the combination and 28.6 months with cabozantinib, a hazard ratio of 0.85. The full results are scheduled for presentation at the European Society for Medical Oncology Congress 2026 in Madrid, running October 23 to 27, Merck said in a statement. Merck's announcement with the trial data is here.

Side effects and safety warnings

Patients stayed on the new combination longer than on cabozantinib, with a median treatment duration of 16.8 months versus 13.2 months. The most common side effects of the pair were anaemia, reported in 69.2 percent of patients, high blood pressure in 58.8 percent, and diarrhoea in 52.7 percent. On cabozantinib, the most frequent were diarrhoea at 70.1 percent, high blood pressure at 56.6 percent, and skin toxicity at 51.2 percent, according to reporting by Targeted Oncology. Their breakdown of the approval data is here.

The belzutifan prescribing information carries a boxed warning for embryo-foetal toxicity, along with warnings for anaemia and hypoxia. For the combination, the FDA added a warning for cardiac dysfunction. The lenvatinib label separately warns about hypertension, blood clots, liver problems, proteinuria, diarrhoea, bleeding, thyroid dysfunction and impaired wound healing, among others, according to AJMC's coverage of the approval. AJMC's safety summary is here.

A growing role for belzutifan

This is not belzutifan's first FDA approval. In June 2026, the agency approved belzutifan with pembrolizumab as adjuvant therapy for patients with clear-cell kidney cancer at intermediate-high or high risk of recurrence, based on the LITESPARK-022 trial. The drug had already been approved for use after prior immunotherapy and VEGF targeted therapy in kidney cancer, and for advanced pheochromocytoma and paraganglioma, a rare adrenal tumour, according to Targeted Oncology.

M. Catherine Pietanza, vice president of global clinical development at Merck Research Laboratories, said in a statement: "WELIREG plus LENVIMA is now the first approved regimen of its kind, offering a new treatment option for certain patients with advanced renal cell carcinoma who have progressed after anti-PD-1/PD-L1 therapy. This approval represents real progress for patients and further reinforces the importance of an HIF-2α inhibitor plus TKI combination as a new treatment approach for these patients."

Why it matters for patients

For people whose kidney cancer has outlasted immunotherapy, treatment choices narrow fast, and the drugs that remain often work through the same pathways. A combination built around that mechanism gives oncologists a different option to reach for, and the trial data show it kept disease progression at bay longer than the current standard.

The boxed warning matters too: belzutifan can harm an unborn child, so patients who could become pregnant need to use effective contraception during treatment and discuss the risks with their oncologist. The approval also comes with a reminder that overall survival has not yet been shown to improve. For eligible patients, though, the decision opens another oral option — one that researchers will present in full detail in Madrid this October.