Merck has just received FDA approval for their recently acquired drug Welireg. This HIF-2α blocker is indicated for von Hippel-Lindau disease (VHL). This rare disease gives affected individuals a higher chance of developing a number of cancers, as it causes tumors and cysts to form throughout the body. As there are at least 10,000 VHL patients within the United States, this approval marks a large step in the right direction for patients. 

Welireg for VHL

Welireg works to inhibit the hypoxia-inducible factor-2 alpha (HIF-2α) protein, which typically accumulates in VHL patients. This build-up leads to a rapid increase in red blood cells, which then leads to the cancers that characterize this condition. 

Due to this ability, the drug has been approved to treat a number of cancers related to VHL, such as renal cell carcinoma, pancreatic neuroendocrine tumors (pNETs), and central nervous system hemangioblastomas that do not require immediate surgery. 

The FDA was expected to release their decision regarding Welireg’s approval in September, but now that the decision has been made, supplies are expected to be available by that time. Approval was made based on the following results from a Phase 2 trial, in which patients received 120 mg of Welireg daily:

• Complete or partial response in 49% of renal cell carcinoma patients
  • Median response time of eight months
  • More than 50% of participants experienced a response time of 12 months
• Response rate of 63% in patients with central nervous system hemangioblastomas
• Response rate of 83% in patients with pNETs

Looking Forward

Merck is not stopping with this recent approval. They are still working on gaining approval for additional indications, such as late-stage renal cell carcinoma. Studies are also investigating Welireg in combination with Keytruda and lenvatinib. 

About VHL

Von Hippel-Lindau disease is a rare, genetic disease that is characterized by cysts and tumors (either benign or malignant) growing throughout the body, typically in the inner ear, spine, kidneys, genital tract, brain, retina, pancreas, and adrenal tract. Additionally, affected individuals live with a higher risk of certain cancers, such as renal cell carcinoma and pNETs. This condition is the result of a mutated VHL gene, which is inherited in an autosomal dominant pattern if passed down. However, in about 20% of cases, the mutation is sporadic. 

Symptoms tend to appear when patients are in their early 20’s, and they include:

• Hemangioblastomas in the brain, retina, and/or spine
• Headaches
• High blood pressure
• Problems with vision, hearing, and/or balance
• Sweating
• Panic attacks
• Changes in pancreatic function

Treatment for this condition consists of removing tumors as they appear and treating cancer if it develops. More treatment options are necessary for this condition. 

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