On May 14, 2025, the U.S. Food and Drug Administration (FDA) approved Welireg (belzutifan), developed by Merck & Co., Inc., for the treatment of adults and adolescents aged 12 and older with locally advanced, unresectable or metastatic pheochromocytoma or paraganglioma (PPGL).
This marks a historic milestone as Welireg becomes the first FDA-approved oral therapy for these rare neuroendocrine tumors, which arise in or around the adrenal glands and affect an estimated 2,000 individuals in the U.S. each year. These tumors can be life-threatening, especially when surgery is not an option or when they spread to distant organs.
Welireg is a hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor that works by targeting abnormal pathways involved in tumor growth under low-oxygen conditions, which are commonly observed in PPGL.
The approval was based on clinical data demonstrating the drug’s ability to reduce tumor burden and control disease progression in patients with advanced forms of PPGL.
The expanded indication adds to Welireg’s existing use in treating certain kidney cancers associated with von Hippel-Lindau (VHL) disease, further establishing its role in targeting hypoxia-driven tumors.
Disclaimer: This article is for informational purposes only and should not be considered medical advice. Patients are advised to speak with their healthcare provider to understand the risks and benefits of Welireg and to determine if it is appropriate for their condition.
