New research from the National Eye Institute brings encouraging news for families living with von Hippel-Lindau (VHL) disease. A published study in the journal Ophthalmology Retina shows that Welireg (belzutifan) can significantly shrink VHL-related eye tumors, known as retinal hemangioblastomas.
What Are Retinal Tumors in VHL?
Retinal hemangioblastomas are small, tangled knots of blood vessels that grow on the retina, the light-sensing tissue lining the back of the eye. Up to 70% of people with VHL develop these eye tumors.
Left untreated, these tumors can leak fluid, bleed, and cause swelling or scarring. Over time, this fluid can pull on the retina and harm a person’s vision. Standard treatments like lasers and freezing (cryotherapy) can help, but they work best on tumors near the edges of the eye. Tumors that grow right next to the optic nerve (the nerve connecting the eye to the brain) are very risky to treat with lasers because laser burns can permanently damage eyesight.
What Did the Study Find?
Doctors at the National Eye Institute looked at 33 people with VHL who had active eye tumors and were taking belzutifan. Across these patients, the team tracked 85 eye tumors in 42 eyes.
The results showed clear benefits:
- Tumors shrank significantly: On average, the size of the eye tumors decreased by 75% after one year and by nearly 80% after two years.
- Some tumors vanished: Nearly 23% of the tumors went away completely. Another 45% turned into harmless, quiet scars. Smaller tumors were the most likely to disappear entirely.
- Leaking and swelling stopped: Fluid leaking from tumors dropped to almost zero by year two, and swollen, twisted blood vessels calmed down.
- Help for hard-to-treat spots: Tumors sitting right by the optic nerve also shrank safely without damaging central vision.
- No new tumors while on the pill: Not a single patient developed a new eye tumor while actively taking belzutifan.
Why You Cannot Stop Taking It Suddenly
The study also revealed an important lesson: belzutifan controls the tumors, but it does not cure them.
Eight patients in the study stopped taking the medication for various reasons. In more than 70% of their eyes, the tumors began to grow again, leak fluid, or flare back up once the medicine was stopped. A few patients even developed new eye tumors after stopping.
This tells doctors that belzutifan may need to be taken continuously over a long period to keep the eyes healthy and prevent tumors from coming back, although more research is needed.
Things to Keep in Mind
While these findings bring hope, belzutifan is a serious medicine. Its most common side effects include anemia (low red blood cell count, which makes you feel tired), fatigue, headaches, and dizziness. It can also harm an unborn baby, so it must not be taken during pregnancy.
In addition, belzutifan is currently approved by the U.S. Food and Drug Administration (FDA) for VHL-related kidney, brain, spinal, and pancreatic tumors, but it is not yet officially approved for eye tumors alone. Because the medication is costly, insurance coverage for eye-only use can still be a hurdle. We hope that this study increases the likelihood that the FDA considers approval for use of belzutifan to treat VHL-related retinal tumors.
Looking Ahead
For families in the VHL community, this study shows that a medicine can protect eyes, shrink difficult tumors, and prevent new growths from forming. If you or a loved one has VHL-related retinal tumors, especially ones near the optic nerve that are difficult to treat with lasers, talk with your retina specialist and care team to see if systemic therapy with belzutifan is right for your overall treatment plan.
Explore More VHL Research
Want to dig deeper into studies like this one? The VHL Research Library is a curated collection of published VHL research papers for patients, families, researchers, and healthcare professionals. You can browse articles on belzutifan, retinal tumors, and every part of the body VHL can affect, then bring your questions to your next appointment. It’s a great way to stay current on the science and take an active role in conversations with your care team.
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