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FDA Approval: Belzutifan (Welireg) for Kidney Cancer
FDA approved Belzutifan (Welireg), a HIF-2α inhibitor, for certain people with kidney cancer. What was approved, the evidence, and what it does and doesn't mean.
Original commentary from the Cancer Explained editorial team.
Please note: this page is educational only — it is not medical advice, and it does not speculate about anyone’s health beyond reliable public reporting. For questions about your own health, talk with your healthcare team.
A drug for a broken oxygen switch
Belzutifan, sold as Welireg, is a HIF-2 alpha inhibitor. Its FDA label carries an Initial U.S. Approval date of 2021.
HIF-2 alpha is a protein that tells a cell it is short of oxygen. In healthy kidney tissue, a protein made by the VHL gene keeps that signal switched off when oxygen is fine. When the VHL gene is faulty, the off switch fails. The cell behaves as if it is permanently starved of oxygen and starts building blood vessels and growing.
That failure is the central defect in clear cell renal cell carcinoma, and in von Hippel-Lindau disease. Belzutifan blocks the stuck signal directly.
What it is approved for
NCI lists two settings.
The first is cancers linked to von Hippel-Lindau disease that need treatment but not immediate surgery. In adults, that covers three tumors. They are hemangioblastoma of the central nervous system, pancreatic neuroendocrine tumors, and renal cell carcinoma. It also covers pheochromocytoma or paraganglioma that has spread or cannot be removed by surgery. There it is used in adults and in children aged 12 and older.
The second is advanced renal cell carcinoma in adults already treated with anti-VEGF therapy and with either anti-PD-1 or anti-PD-L1 therapy.
The trial behind the kidney cancer approval
On December 14, 2023, the FDA approved belzutifan for advanced renal cell carcinoma after a PD-1 or PD-L1 inhibitor and a VEGF tyrosine kinase inhibitor.
The evidence was LITESPARK-005, an open-label randomized head-to-head trial. It enrolled 746 patients with clear cell RCC that could not be removed by surgery. Their disease had progressed after both drug classes. They were randomized one to one to belzutifan 120 mg or everolimus 10 mg once daily. These were the trial's set amounts, not advice for any one person.
The main outcomes were progression-free survival, judged by blinded independent central review, and overall survival.
Progression-free survival improved significantly, with a hazard ratio of 0.75. A hazard ratio below 1 favors the new drug. Yet the median PFS estimates were nearly identical, at 5.6 months in both arms. The FDA notes the curves showed non-proportional hazards, meaning the benefit was not spread evenly over time.
Overall survival results were immature, with 59 percent of deaths reported, and no trend toward harm was seen. A descriptive analysis of patient-reported symptoms supported better tolerability than everolimus.
Two identical medians with a significant hazard ratio is a good lesson in reading trial results. The median is one point on a curve. The hazard ratio summarizes the whole curve.
Side effects
The FDA lists the reactions seen in 25 percent or more of patients. They were low hemoglobin, fatigue, and muscle and joint pain. They also included a rise in creatinine, a drop in lymphocytes, and a drop in sodium. Potassium rose. Two liver enzymes rose as well.
Several of those are lab findings, not symptoms. That is why blood tests are routine on this drug. Low hemoglobin is the one most likely to be felt, as fatigue and breathlessness.
The dose is 120 mg by mouth once daily, continued until the disease progresses or side effects become unacceptable.
That is the approved reference amount. Your own team writes your prescription and will pause or reduce it if your haemoglobin or oxygen levels drop.
When to get checked
NCI notes that renal cell cancer may cause no signs or symptoms in early stages, and that symptoms appear as the tumor grows. Check with a doctor for:
- Blood in the urine.
- A lump in the abdomen.
- Pain in the side that does not go away.
- Loss of appetite.
- Weight loss for no known reason.
- Anemia.
There is no routine screening test for kidney cancer in people at average risk.
NCI lists the risk factors. They are smoking tobacco and long-term misuse of certain pain medicines, including over-the-counter ones. Excess body weight and high blood pressure are on the list too. So is a family history of renal cell cancer. So are genetic conditions such as von Hippel-Lindau disease and hereditary papillary renal cancer.
People known to have von Hippel-Lindau disease are followed on a set schedule. The condition raises risk of tumors in several organs at once.
Ultrasound, urine, and CT
Tests of the abdomen and kidneys make the diagnosis. Ultrasound bounces sound waves off internal tissues to build a picture. A blood chemistry study measures substances released by organs. Urinalysis checks urine for sugar, protein, red cells, and white cells. CT scanning gives detailed pictures of the abdomen and pelvis.
Stage reflects tumor size, spread into nearby tissue and lymph nodes, and spread to distant organs.
Nephrectomy and what follows it
NCI lists surgery, radiation therapy, immunotherapy, and targeted therapy.
Surgery is often the main treatment. A partial nephrectomy removes the cancer and some tissue around it. It is used to preserve kidney function. A simple nephrectomy removes the kidney. A radical nephrectomy removes the kidney and the adrenal gland. It also takes surrounding tissue and, usually, nearby lymph nodes.
A person can live with part of one working kidney. If both kidneys are removed or stop working, dialysis or a kidney transplant is needed.
For advanced disease, drug treatment leads. Our pages on immunotherapy and targeted therapy cover the two classes that come before belzutifan in the sequence.
The numbers by stage
These SEER figures cover kidney and renal pelvis cancer across the US population. They do not describe one person.
Five-year relative survival is 79.2 percent for cases from 2016 to 2022. By stage it is 93.6 percent while confined to the kidney, 77.6 percent once it reaches nearby lymph nodes, and 20.3 percent once it has spread further. About 66 percent are found at that first stage, and 15 percent are already distant. An estimated 80,450 new cases and 15,160 deaths are projected for 2026, and median age at diagnosis is 65.
Our page on kidney cancer covers the disease in more depth.
What this trial cannot tell you
Belzutifan was approved for one spot in the treatment sequence. Two other drug classes come first. It is not a first-line option in that setting.
The overall survival data were not mature at approval. So the question of whether people live longer had not been answered. All that could be said was that no harm signal appeared. Whether the drug fits one person depends on tumor type, prior treatments, blood counts, kidney and liver function, and tolerance.
Sources
- FDA, belzutifan for advanced renal cell carcinoma — https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-belzutifan-advanced-renal-cell-carcinoma
- NCI, Belzutifan — https://www.cancer.gov/about-cancer/treatment/drugs/belzutifan
- DailyMed, WELIREG (belzutifan) label, Initial U.S. Approval 2021 — https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=13e15ee0-d679-4fa9-9430-e2e2170474da
- NCI PDQ, Renal Cell Cancer Treatment (Patient Version) — https://www.cancer.gov/types/kidney/patient/kidney-treatment-pdq
- SEER Cancer Stat Facts, Kidney and Renal Pelvis Cancer — https://seer.cancer.gov/statfacts/html/kidrp.html
How this article was prepared
An AI-assisted editorial system helped prepare this page. No named medical reviewer has reviewed it unless one is listed.
The National Cancer Information Foundation publishes Cancer Explained. This page is for learning. It is not medical advice and does not suggest a test or treatment.
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Put the story in context
Prevention, possible warning signs, screening, and diagnosis
This story relates to Kidney cancer. The information below is general: it does not reveal anything else about a public person’s health, and not every point applies to every cancer. Personal advice depends on age, symptoms, family history, exposures, and medical history.
Prevention and risk reduction
Not every cancer can be prevented. Avoiding tobacco, protecting skin from ultraviolet radiation, limiting alcohol, staying active, and receiving recommended HPV or hepatitis B vaccination can lower the risk of certain cancers. A risk factor is not a prediction or a cause in one individual.
Symptoms and possible early signs
Possible signs vary and are often caused by conditions other than cancer. Changes worth discussing include a new lump, unexplained bleeding or weight loss, a persistent cough, lasting bowel or bladder changes, a changing skin spot, or symptoms that persist or worsen. Some early cancers cause no symptoms.
Screening and early detection
Screening looks for certain cancers before symptoms begin. Recommended tests exist only for some cancers and depend on age and risk. Screening can have benefits and harms; it is not the same as evaluating a new symptom, and there is no single routine scan or blood test that reliably screens for every cancer.
How cancer is diagnosed
Diagnosis may involve a history and exam, imaging, laboratory tests, and often a biopsy. Pathology can identify the cancer type and may test biomarkers that guide treatment. Symptoms, screening results, tumor markers, or online stories alone cannot confirm cancer.
Learn about this story’s cancer topic
A public story may encourage questions, but it should not be used to estimate your risk or choose testing. Contact a healthcare professional about a persistent or concerning change. Seek urgent care for severe or rapidly worsening symptoms.