Neither Welireg nor Merck's anti-CTLA-4 agent quavonlimab added benefits on top of Keytruda and Lenvima in first-line kidney cancer.
After prevailing in two kidney cancer trials in the refractory and early-stage settings, Merck & Co.’s blockbuster prospect Welireg surprisingly failed to ignite hope as a first-line treatment.Welireg did not improve progression-free survival or overall survival when added to a combination of Merck’s Keytruda and Lenvima as first-line treatment for advanced clear cell renal cell carcinoma (ccRCC), the company said Tuesday.The negative result, from a prespecified interim analysis of the phase 3 Litespark-012 trial, comes as a major surprise. After two positive phase 3 readouts, the first-in-class HIF-2 alpha inhibitor is in the running to set new treatment standards for patients with advanced ccRCC who have failed on previous immunotherapy and for early-stage patients with resected ccRCC who’re at an increased risk of recurrence following surgery.Following the Litespark-011 and -022 wins, a genitourinary cancer expert predicted to Leerink Partners that the first-line Litespark-012 trial would be “wildly positive” on PFS since it is “hard to believe an adjuvant and two refractory studies are positive and somehow the first-line will be negative,” according to a March 3 Leerink note. The other positive refractory study for Welireg is Litespark-005, in which the Merck drug outperformed Novartis’ Afinitor on PFS but not OS.With the prior phase 3 wins, Leerink analysts previously suggested that Welireg’s consensus peak sales expectations of around $2.6 billion “underestimate the drug’s role in ccRCC.” First approved by the FDA in 2021 for von Hippel-Lindau disease, Welireg became a kidney cancer treatment at the end of 2023. Last year, the drug’s $716 million in global sales marked a 41% jump year-over-year. Meanwhile, certain aspects of the Litespark-011 and -022 readouts could prevent Welireg from becoming the unchallenged standard of care in the second-line and adjuvant settings. While the Welireg-Lenvima combo’s PFS win could drive some adoption in the second line, OS has not met statistical significance. Two genitourinary cancer experts that Leerink spoke with both shared reservations about the regimen because of its Lenvima component—but for different reasons. One expert primarily uses Lenvima for first-line treatment and was not interested in changing that practice just to accommodate a second-line option. The other one wanted to save Lenvima as a valuable salvage option and would be reluctant to use it in the second line.The FDA is reviewing Merck’s application based on Litespark-011, with a target action date of Oct. 4, 2026.As for the adjuvant setting, the two experts agreed that despite a disease-free survival triumph, the Litespark-022 data are still too immature to justify broad usage given the widespread understanding within the medical community that it’s best to avoid over-treating patients in a setting where most are cured by surgery, according to Leerink.Besides Merck, Arcus Biosciences is developing a rival HIF-2α inhibitor called casdatifan. Despite promising data, Gilead Sciences passed on its chance to license the drug last year.Merck’s April 21 announcement actually included a second flop. A third arm of Litespark-012, which evaluated MK-1308A, a coformulation of Keytruda and Merck’s CTLA-4 antibody quavonlimab, plus Lenvima, also failed to beat Keytruda and Lenvima on the trial’s dual primary endpoints of PFS and OS in first-line ccRCC. This combination appeared to be a wild card for Merck anyway. Before the readout, Leerink analysts said they were “highly pessimistic” on this comparison after Exelixis’ Cosmic-313 trial of a pairing of its Cabometyx and Bristol Myers Squibb’s Opdivo and Yervoy showed that the addition of a CTLA-4 agent may backfire. “While these regimens did not demonstrate the results we hoped, the data deepen our understanding of advanced renal cell carcinoma and will help shape the next generation of treatment approaches,” Catherine Pietanza, M.D., VP of global clinical development at Merck Research Laboratories, said in a statement Tuesday. Results from the Litespark-012 trial do not affect other ongoing trials from the Litespark program for Welireg, Merck said. Through a collaboration with Exelixis, Merck is running the phase 3 Litespark-033 trial testing Welireg alongside the biotech’s investigational tyrosine kinase inhibitor zanzalintinib in frontline kidney cancer patients who had been treated with Keytruda in the adjuvant setting.