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Belzutifan is the first HIF-2α inhibitor, born from Nobel-winning biology, and is now approved after kidney cancer surgery with pembrolizumab.
Belzutifan is a small-molecule HIF-2-alpha inhibitor that blocks HIF-2-alpha from dimerising with ARNT, silencing the hypoxia programme that drives clear-cell kidney cancer when VHL is lost; it is taken as 120 mg once daily. It was approved in 2021 for VHL disease-associated renal cell carcinoma, CNS haemangioblastoma and pancreatic neuroendocrine tumours, in 2023 for advanced RCC after PD-1/PD-L1 and VEGF-TKI therapy (LITESPARK-005), in 2025 for pheochromocytoma and paraganglioma, and in Q2 2026 as adjuvant therapy for clear-cell RCC with pembrolizumab (LITESPARK-022). Merck markets it. Anaemia and hypoxia are on-mechanism effects because HIF-2-alpha regulates erythropoietin. Whether the adjuvant benefit translates into survival, and which patients respond, remain open. For a newcomer: the first drug from the Nobel-winning biology of how cells sense oxygen.
Blocks HIF-2α/ARNT dimerisation. Connects to HIF-2α.
1.Belzutifan binds the PAS-B pocket of HIF-2α
Source: www.fda.gov/drugs/resources-information-approved-drugs/oncology-cancer-hematologic-malignancies-approval-notifications. Doses are for orientation; the current label governs.
Oral, self-administered, so it is a Part D drug: covered through a stand-alone Part D plan or Medicare Advantage drug benefit, usually on the specialty tier with 25 to 33% coinsurance until the annual cap ($2,000 in 2025, $2,100 in 2026).
Covered for FDA-labelled and NCCN-listed uses, but almost always behind prior authorisation confirming diagnosis, biomarker and line of therapy; dispensed through a specialty pharmacy. VHL disease or prior immunotherapy and VEGF-TKI for RCC.
Part D out-of-pocket capped at $2,000 (2025) / $2,100 (2026). Medicare patients cannot use manufacturer co-pay cards; charity funds (PAN, HealthWell, CancerCare) and the Extra Help subsidy are the routes.
Sources: Medicare.gov: Drug coverage (Part D) · Medicare.gov: Costs for Medicare drug coverage (annual out-of-pocket cap). Not medical or financial advice; verify with your plan.
Sources: NICE TA1011 · NHS England Cancer Drugs Fund list. Funding decisions are indication-specific and change monthly; verify with NICE and your treating team.
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VHL disease-associated RCC, CNS haemangioblastoma, pNET: first HIF-2α inhibitor source
Advanced RCC after PD-1/PD-L1 and VEGF-TKI (LITESPARK-005) source
Pheochromocytoma/paraganglioma source
Adjuvant clear-cell RCC with pembrolizumab (LITESPARK-022) source
With lenvatinib, advanced renal cell carcinoma with a clear cell component source
| Region | Year | Indication |
|---|---|---|
| US | 2021 | VHL-associated RCC, CNS haemangioblastoma, pNET |
| US | 2023 | Advanced RCC after PD-1/PD-L1 and VEGF-TKI |
| US | 2026 | Adjuvant clear-cell RCC with pembrolizumab |
| EU | 2025 | ccRCC after ≥2 lines; VHL-associated tumours; 12 Feb 2025 (conditional) · Conditional marketing authorisation |
| Adverse event |
|---|
| Anaemia |
| Hypoxia |
| Fatigue |
| Nausea |
| Oedema |
| Dyspnoea |
LITESPARK-005: ~83% any grade, ~33% grade 3. Events listed without rates were not read from a primary source; see the label. Blank cells mean the figure was not sourced, not that it is zero.
| Country | Reimbursement | List price | Assistance |
|---|---|---|---|
| United States | Medicare Part D (oral); commercial plans per formulary, often with prior authorisation | not disclosed | merckaccessprogram-welireg.com |
| United Kingdom | NICE: appraisal for RCC after IO and VEGF-TKI (2025-26) | not disclosed | - |
List prices are manufacturer or Medicare figures where publicly disclosed; net prices after rebates are usually lower. Reimbursement changes; check the payer.
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There has been no clear standard for clear-cell kidney cancer that progresses after immunotherapy; this is the first phase 3 to show a HIF-2 alpha inhibitor combination beating a standard tyrosine kinase inhibitor on progression-free survival in that setting. Whether it changes practice depends on the final overall survival analysis and on regulators, since the interim survival difference did not reach significance and the combination brings the toxicity of two drugs.
Belzutifan is the first systemic therapy for von Hippel-Lindau disease, approved for renal, central nervous system and pancreatic tumours not needing immediate surgery, changing a lifetime of surveillance and surgery for many patients.
Query for this drug: (TITLE:"Belzutifan" OR ABSTRACT:"Belzutifan" OR TITLE:"Welireg" OR ABSTRACT:"Welireg") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Belzutifan, not a curated reading list.
Shares A Trial of Belzutifan (PT2977, MK-6482) in Combination With Cabozantinib in Patients With Clear Cell Renal Cell Carcinoma (ccRCC) (MK-6482-003), Extension Study for Participants in Studies That Include Belzutifan (MK-6482-043/LITESPARK-043), Belzutifan plus lenvatinib versus cabozantinib in patients with previously treated advanced renal cell carcinoma (LITESPARK-011): an open-label, randomised, controlled, phase 3 trial, LITESPARK-011.
Shares LITESPARK-012, Substudy 03A: A Study of Immune and Targeted Combination Therapies in Participants With First Line (1L) Renal Cell Carcinoma (MK-3475-03A), Substudy 03B: A Study of Immune and Targeted Combination Therapies in Participants With Second Line Plus (2L+) Renal Cell Carcinoma (MK-3475-03B/KEYMAKER-U03), Extension Study for Participants in Studies That Include Belzutifan (MK-6482-043/LITESPARK-043).
Shares Belzutifan/MK-6482 for the Treatment of Advanced Pheochromocytoma/Paraganglioma (PPGL), Pancreatic Neuroendocrine Tumor (pNET), Von Hippel-Lindau (VHL, VHL / HIF oxygen sensing, Renal cell carcinoma (KEGG map), Pheochromocytoma and paraganglioma (PPGL).
Shares Angiogenesis, VHL / HIF oxygen sensing, HIF-2α, The angiogenic switch & tumour vessels.
Shares Belzutifan for renal cell carcinoma and other tumours in von Hippel-Lindau disease, Spinal cord tumours (intramedullary and intradural), Clear cell renal cell carcinoma, Renal cell carcinoma.
Shares Biomarker-selected adjuvant therapy in RCC (ctDNA, CAIX PET, gene signatures), Toni K. Choueiri, Clear cell renal cell carcinoma, Merck & Co. (MSD).
Shares HIF-1α (HIF1A), Choline metabolism in cancer, Renal cell carcinoma (KEGG map), Pancreatic neuroendocrine tumours.
Shares Biomarker-selected adjuvant therapy in RCC (ctDNA, CAIX PET, gene signatures), Toni K. Choueiri, Clear cell renal cell carcinoma, Merck & Co. (MSD).