Merck & Co. has received U.S. FDA approval for a combination of Welireg and Keytruda as an adjuvant treatment for adults with clear cell renal cell carcinoma (ccRCC) who face an intermediate-high or high risk of recurrence following kidney removal surgery. The approval marks the first authorization of a treatment regimen that combines a PD-1 inhibitor with a HIF-2 alpha inhibitor.
Under the approval, Welireg may be used alongside standard Keytruda or the subcutaneous formulation, Keytruda Qlex. The decision expands Welireg’s use into earlier-stage ccRCC following its previous approval in advanced renal cell carcinoma in 2023.
The FDA decision was supported by results from the phase 3 Litespark-022 trial, which enrolled 1,841 patients. The study compared Welireg plus Keytruda against Keytruda with placebo in the adjuvant setting. According to the trial findings, the combination reduced the risk of disease recurrence, metastasis, or death by 28% compared with the control regimen. Estimated disease-free survival was 81% in the Welireg-Keytruda group versus 74% among patients who received Keytruda and placebo.
Litespark-022 was the first adjuvant trial in kidney cancer to show a benefit for a combination treatment over a PD-1 agent alone. Following the presentation of the data earlier this year, Cathy Pietanza, M.D., vice president of global clinical development at Merck Research Laboratories, described the findings as very compelling. Toni Choueiri, M.D., of the Dana-Farber Cancer Institute and lead author of the study, said during a press call that the results could support the regimen as a new standard of care for patients at increased risk of recurrence.
Although disease-free survival results were positive, overall survival data from Litespark-022 remain immature. Pietanza noted that preventing recurrence in the adjuvant setting is meaningful because it helps patients avoid having to worry about the next line of treatment.
“Reflecting on my own experience as a clinical oncologist, I know the significant impact that improved disease-free survival can have on the lives of patients,” Pietanza explained in Merck’s release.
The approval adds to a series of regulatory milestones for Welireg. The therapy entered Merck’s portfolio through its acquisition of Peloton in 2019. It first received FDA approval in 2021 for certain tumors associated with von Hippel-Lindau disease. Welireg later gained its first kidney cancer indication in 2023 and expanded in 2025 to include treatment of rare pheochromocytoma and paraganglioma tumors.
Welireg generated $716 million in revenue in 2025, representing 41% year-over-year growth. Keytruda and Keytruda Qlex together produced $31.7 billion in sales during the same period and accounted for nearly half of Merck’s total revenue.
Analysts at Leerink Partners previously wrote that Welireg could become a “substantial revenue contributor” for Merck following positive phase 3 results in both the adjuvant setting and a separate second-line kidney cancer study involving Eisai-partnered Lenvima. After reviewing detailed trial data, the analysts said they expect adoption in the adjuvant setting to build more slowly because overall survival results remain immature and there is ongoing debate about over-treatment in the setting. The firm raised its 2028 Welireg sales estimate by 36% to $3.4 billion.
The regulatory decision was based on results from a large clinical study that evaluated the effectiveness of the combination therapy in patients who had undergone surgery for clear cell renal cell carcinoma. Researchers found that patients receiving the dual-treatment approach experienced a meaningful reduction in the risk of disease recurrence compared with standard treatment strategies.
The study also demonstrated a manageable safety profile consistent with the known characteristics of both medicines. These findings provided regulators with strong evidence that the combination could offer substantial benefits for patients who remain vulnerable to cancer returning after surgery.
Welireg has achieved an important regulatory milestone after receiving FDA approval in combination with Keytruda for the adjuvant treatment of clear cell renal cell carcinoma (ccRCC).
FDA Approval Marks a Major Achievement for Welireg
The latest approval strengthens the clinical profile of Welireg and highlights its growing importance in the treatment of kidney cancer.
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