Merck, known as MSD outside the US and Canada, has received approval from the US Food and Drug Administration (FDA) for its drug Welireg (belzutifan).
Welireg is an oral hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor, indicated for adults and children aged 12 and older with advanced pheochromocytoma or paraganglioma (PPGL).
PPGL refer to rare tumours that originate from the same tissue, with pheochromocytoma forming in the adrenal gland and paraganglioma outside it.
The drug is already approved in the US for treating certain von Hippel-Lindau (VHL) disease-associated tumours in adult patients not requiring immediate surgery.
The tumour types include renal cell carcinoma, central nervous system hemangioblastomas, or pancreatic neuroendocrine tumours.
Welireg comes with a label containing a boxed warning about potential embryo-foetal harm if used during pregnancy.
monitoring for anaemia and oxygen saturation is recommended before and during treatment.
Merck Research Laboratories global clinical development senior vice president and oncology head Marjorie Green said: “For patients with advanced PPGL, there has been a lack of approved systemic treatment options available to help manage their disease, underscoring the importance of this approval in the US.
“This approval marks the third indication for WELIREG in the US and demonstrates our company’s commitment to providing innovative cancer therapies for patients in need, including those with rare diseases.”
The FDA approval is based on data from the LITESPARK-015 clinical trial, a single-arm study focusing on the objective response rate (ORR) as the primary endpoint.
The LITESPARK-015 is an open-label, multicohort Phase 2 study that enrolled 72 patients with measurable disease verified by blinded independent central review (BICR).
The study excluded patients with carcinomatous meningitis and enrolled participants with a documented histopathological diagnosis of PPGL and adequately controlled blood pressure.
Patients in the study received a daily dose of 120 mg until disease progression or unacceptable toxicity.
The study results confirmed the efficacy of Welireg in treating advanced PPGL.
Welireg may cause severe anaemia, potentially requiring blood transfusions, and severe hypoxia, which could necessitate discontinuation, supplemental oxygen, or hospitalisation.
Patients are advised to verify pregnancy status before starting treatment and use effective non-hormonal contraception.
