FDA approves WELIREG (belzutifan) plus LENVIMA (lenvatinib) for advanced clear cell renal cell carcinoma after PD-1/PD-L1 therapy.
Written By: Kalyani Boharapi,
M.Pharm (Reg. Affairs)
Reviewed By: Pharmacally Editorial Team
Merck and Eisai received U.S. FDA approval for belzutifan plus lenvatinib in adults with advanced clear cell renal cell carcinoma (ccRCC) following treatment with a PD-1 or PD-L1 inhibitor, based on Phase 3 LITESPARK-011 results showing longer progression-free survival and higher response rates than cabozantinib.
FDA Approval Expands Treatment Options After Immunotherapy
The FDA approval establishes WELIREG (belzutifan) plus LENVIMA (lenvatinib) as a new treatment option for patients whose advanced ccRCC has progressed after PD-1/PD-L1 inhibitor therapy. The combination brings together two distinct approaches: HIF-2α inhibition and multi-targeted VEGFR tyrosine kinase inhibition.
The decision is particularly relevant to a treatment setting where options become more limited after progression on immunotherapy. Clear cell RCC represents about 70% of RCC cases, while approximately 32% of kidney cancer patients are diagnosed with regional or metastatic disease.
LITESPARK-011 Shows PFS and Response Benefit
LITESPARK-011 (NCT04586231) was a randomized, open-label Phase 3 trial involving 747 patients with locally advanced or metastatic ccRCC who had progressed on or after PD-1/PD-L1 inhibitor therapy, or within six months of completing adjuvant PD-1 therapy. Patients received WELIREG 120 mg once daily plus LENVIMA 20 mg once daily, or cabozantinib 60 mg once daily.
At the prespecified interim analysis, the combination reduced the risk of disease progression or death by 26% compared with cabozantinib (HR 0.74; 95% CI, 0.61-0.89; p=0.001). Median progression-free survival reached 14.6 months with WELIREG plus LENVIMA versus 10.6 months with cabozantinib.
Overall survival numerically favored WELIREG plus LENVIMA, with median OS of 33.7 months versus 28.6 months with cabozantinib (HR 0.85; 95% CI, 0.70–1.03). However, the final OS analysis did not reach statistical significance. The combination also produced a higher objective response rate of 53% versus 40% (p=0.0002).
Dual-Pathway Biology Supports the Combination
Belzutifan is an oral HIF-2α inhibitor that blocks the interaction between HIF-2α and HIF-1β. This suppresses transcription of HIF-2α-regulated genes involved in tumor growth, angiogenesis and cellular proliferation. Lenvatinib inhibits multiple receptor tyrosine kinases, including VEGFR pathways that support tumor vascularization.
The combination therefore targets complementary mechanisms involved in ccRCC biology rather than relying on a single signaling pathway.
Safety Requires Intensive Monitoring
The safety profile reflects clinically important toxicities from both agents. Serious adverse reactions occurred in 54% of patients receiving the combination, with hypoxia, pneumonia, hyponatremia, acute kidney injury, hemorrhage, anemia, cardiac failure and diarrhea among the serious events reported. Fatal adverse reactions occurred in 5% of patients.
Treatment modification was common. Adverse reactions led to dose interruptions in 69% of patients for WELIREG and 72% for LENVIMA, while dose reductions occurred in 35% and 67%, respectively. Permanent discontinuation occurred in 17% of patients for WELIREG and 23% for LENVIMA.
WELIREG carries a boxed warning for embryo-fetal toxicity and can cause severe anemia and hypoxia. The combination can also cause serious cardiac dysfunction, including heart failure and reduced left ventricular ejection fraction, requiring monitoring during treatment.
Path Forward
Updated LITESPARK-011 findings are scheduled for presentation at the 2026 ESMO Congress in Madrid. The FDA approval adds a new HIF-2α inhibitor plus VEGFR-TKI regimen for patients with advanced ccRCC progressing after PD-1/PD-L1 therapy.
Reference
U.S. FDA Approves WELIREG® (belzutifan) Plus LENVIMA® (lenvatinib) for Certain Previously Treated Adult Patients with Advanced Renal Cell Carcinoma with a Clear Cell Component (ccRCC), MERCK, 25 September 2026
A Study of Belzutifan (MK-6482) in Combination With Lenvatinib Versus Cabozantinib for Treatment of Renal Cell Carcinoma (MK-6482-011), ClinicalTrials.gov ID NCT04586231
About the Writer
Kalyani Boharapi (LinkedIn) is a pharmacy professional and healthcare writer currently pursuing an M.Pharm in Regulatory Affairs at Dr. D. Y. Patil College of Pharmacy, with interests in pharmaceutical regulations, drug development, and healthcare innovation. She has academic exposure to dossier preparation, scientific writing, and regulatory documentation. Kalyani has also completed certification courses in Generative AI, AI in Pharma, and Bioinformatics, and actively participates in pharmaceutical conferences to stay updated with emerging trends and advancements in the healthcare and pharmaceutical industry.