Since Merck secured approval for kidney cancer pill and blockbuster hopeful Welireg (belzutifan) in August of 2021, sales have grown slowly but surely.
With a second FDA nod on Thursday for a much larger patient population, the company can anticipate a more pronounced upswing in revenue from the hypoxia-inducible factor-2 alpha (HIF-2a) inhibitor.
The U.S. regulator has given a thumbs up for Welireg to treat relapsed or refractory renal cell carcinoma (RCC) for adult patients who have not responded to a PD-1 or PD-L1 inhibitor and who have also been treated with a vascular endothelial growth factor tyrosine kinase inhibitor (VEGF-TK1).
Welireg becomes the first drug in its class for patients with advanced RCC and the first novel-class treatment in the indication since 2015, Merck noted.
The nod comes on top of its original approval to treat the rare von Hippel-Lindau disease, a hereditary condition that causes tumor growth in various organs of the body, most often in the kidney.
Merck hopes Thursday’s label expansion is the first of a few for Welireg in RCC, as the company is investigating the treatment in earlier lines of use. RCC is the most common form of kidney cancer, accounting for roughly 9 of every 10 cases.
In the phase 3 LITESPARK-005 study, Welireg outperformed Novartis’ chemotherapy Afinitor (everolimus), paving the way for the most recent green light. From a pool of 746 patients, after 12 months, 34% of those who received a daily, 120 mg dose of Welireg achieved progression-free survival. That compared with 18% for those on Afinitor.
After 18 months, those figures dropped to 22% and 9%, respectively. Welireg also produced a 22% objective response rate, compared with 4% for Afinitor.
“Despite recent progress in the treatment of advanced RCC, there is yet to be an option specifically approved for patients whose disease progresses following a PD-1 or PD-L1 inhibitor and a TKI therapy,” Toni Choueiri, the LITESPARK-005 study chair and the director of the Lank Center for Genitourinary Oncology at the Dana-Farber Cancer Institute, said in a release.
Merck gained Welireg when it purchased Peloton Therapeutics for $1.05 billion up front in 2019.
In the last three quarters, Welireg sales have climbed from $42 million to $50 million to $54 million. When it was approved in 2021, Bernstein analysts pegged Welireg’s peak sales potential between $1 billion and $1.5 billion if it gains approval to treat earlier-stage RCC patients.

https://www.merck.com/news/fda-accepts-for-priority-review-mercks-supplemental-new-drug-application-for-welireg-belzutifan-in-certain-previously-treated-patients-with-advanced-renal-cell-carcinoma-rcc/