FDA Approves Welireg (belzutifan) for the Treatment of Patients With Certain Types of Von Hippel-Lindau (VHL) Disease-Associated Tumors

Merck (NYSE: MRK),  announced that the U.S. Food and Drug Administration (FDA) has approved 'Welireg, an oral hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor, for the treatment of adult patients with von Hippel-Lindau (VHL) disease who require therapy for associated renal cell carcinoma (RCC), central nervous system (CNS) hemangioblastomas, or pancreatic neuroendocrine tumors (pNET), not requiring immediate surgery. The recommended dose of Welireg (40 mg tablets) is 120 mg once daily until disease progression or unacceptance toxicity. The approval is based on results from the open-label Study 004 trial (N=61), where the major efficacy endpoint was overall response rate (ORR) in patients with VHL-associated RCC.

Welireg is the first HIF-2α inhibitor therapy approved in the U.S. As an inhibitor of HIF-2α, Welireg reduces transcription and expression of HIF-2α target genes associated with cellular proliferation, angiogenesis and tumor growth.

The Welireg label contains a boxed warning that exposure to Welireg during pregnancy can cause embryo-fetal harm. Verify pregnancy status prior to the initiation of Welireg. Advise patients of these risks and the need for effective non-hormonal contraception. Welireg can render some hormonal contraceptives ineffective. Welireg can cause severe anemia that can require a blood transfusion. Monitor for anemia before initiation of Welireg and periodically throughout treatment. Welireg can cause severe hypoxia that may require discontinuation, supplemental oxygen, or hospitalization. Monitor oxygen saturation before initiation of and periodically throughout treatment with Welireg. For more information, see "Selected Safety Information" below.

“VHL disease is a rare and serious condition. Until today, there were no systemic therapies approved to help treat patients diagnosed with certain types of VHL-associated tumors,” said Dr. Eric Jonasch, principal investigator of Study 004 and professor, Department of Genitourinary Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center. “The approval of Welireg, which is based on data showing an overall response rate across three different types of VHL-associated tumors, addresses this significant unmet need by introducing a new option for physicians and their patients impacted by this disease.”

“Welireg is the first and only approved systemic therapy for patients with certain types of VHL-associated tumors, representing an important new treatment option for patients affected by this rare condition,” said Dr. Scot Ebbinghaus, vice president, clinical research, Merck Research Laboratories. “Today’s approval of Welireg is a significant milestone and is a testament to Merck’s commitment to bring forward innovative new treatment options for more patients.”

“The approval of a non-surgical treatment option is meaningful for helping patients with certain types of VHL-associated tumors,” said Dr. Ramaprasad Srinivasan, head, Molecular Cancer Therapeutics Section, Urologic Oncology Branch, National Cancer Institute (NCI), and principal investigator on the Cooperative Research and Development Agreement (CRADA) under which the NCI served as a site in Study 004. “In Study 004, nearly half of all patients with VHL-associated renal cell carcinoma, as well as the majority of patients with VHL-associated central nervous system hemangioblastomas or pancreatic neuroendocrine tumors, who were treated with Welireg experienced a reduction of their respective tumor size. The FDA’s approval of Welireg marks an important step forward by introducing a systemic therapy that has the potential to improve the current treatment paradigm for patients with certain types of VHL-associated tumors.”

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