Shares of Merck & Co. advanced significantly in Friday's trading session, closing higher on substantial volume following a series of key clinical and regulatory announcements. The pharmaceutical giant reported pivotal Phase 3 trial results for its blockbuster immunotherapy Keytruda and the newer agent Welireg across multiple cancer indications, while also securing important U.S. regulatory timelines.
Clinical Data Bolsters Keytruda Franchise
On Friday, Merck announced final data from the KEYNOTE-B96 trial, demonstrating that a combination of Keytruda (pembrolizumab) and chemotherapy improved overall survival in patients with platinum-resistant recurrent ovarian cancer. The regimen reduced the risk of death by 18% compared to paclitaxel, with or without Roche's Avastin (bevacizumab). Median overall survival reached 17.7 months for patients on the Keytruda arm versus 14.0 months for the control group. Dr. Nicoletta Colombo of the European Institute of Oncology in Milan noted the reduced efficacy of traditional treatments in this challenging patient population.
Separately, the company released Phase 3 findings for earlier-stage renal cell carcinoma (kidney cancer) in patients following surgery. Adding Welireg (belzutifan) to Keytruda led to a 28% reduction in the risk of recurrence or death compared to Keytruda alone, with a hazard ratio of 0.72. At the 24-month mark, estimated disease-free survival was 80.7% for the combination therapy, up from 73.7% for Keytruda monotherapy. Dr. Toni K. Choueiri of Dana-Farber Cancer Institute described the combination as a potential practice-changer.
Welireg Combinations Show Promise in Advanced Settings
Merck, in collaboration with Eisai, also presented Phase 3 results in advanced renal cell carcinoma patients previously treated with PD‑1/PD‑L1 inhibitors. The data showed that Welireg combined with Lenvima (lenvatinib) outperformed cabozantinib (marketed as Cabometyx) for progression‑free survival. Median PFS was 14.8 months for the Welireg-Lenvima combination, compared to 10.7 months with cabozantinib. While overall survival data showed a positive trend, it did not reach statistical significance in this interim analysis. Dr. Robert Motzer of Memorial Sloan Kettering highlighted the ongoing challenge of selecting the right treatment in this setting.
Additional data from the LITESPARK-022 trial, presented at the ASCO Genitourinary Cancers Symposium, indicated that approximately 81% of patients treated with pembrolizumab and belzutifan remained cancer-free at follow-up, versus 74% for pembrolizumab alone. Overall survival data from this study are not yet available.
FDA Sets Review Timelines
The U.S. Food and Drug Administration has established target action dates for two key regulatory submissions. For Welireg paired with Keytruda as an adjuvant treatment in kidney cancer, the agency assigned a Prescription Drug User Fee Act (PDUFA) target date of June 19, 2026. Separately, Eisai reported an FDA action date of October 4, 2026, for supplemental filings involving Welireg plus Lenvima in patients with previously treated advanced kidney cancer.
Market Context and Strategic Moves
Merck's reliance on Keytruda remains a central focus for investors. The drug generated over $30 billion in 2025, accounting for nearly half of the company's total revenue. With major patents beginning to expire in 2028, the pressure to diversify the pipeline and secure new growth drivers is intensifying. In response, Merck recently reorganized its Human Health division, creating a dedicated Oncology Business Unit separate from its Specialty, Pharma & Infectious Diseases group. The company announced that Brian Foard will assume the role of president for the non-oncology segment.
Analysts note that while the recent data is compelling, questions remain. In the adjuvant kidney trial, adverse events like anemia and hypoxia were more frequent with the combination therapy. Furthermore, overall survival benefit—a critical metric for both regulators and payers—remains a key hurdle to be cleared in both kidney cancer indications. Some physicians may await more definitive survival data before adopting these regimens broadly for large patient cohorts.
Looking ahead, investors will have an opportunity to hear from Merck's leadership, including CFO Caroline Litchfield and research chief Dean Li, who are scheduled for a fireside chat at the TD Cowen healthcare conference. The company's next ex-dividend date is March 13, with a $0.85 per share cash payout scheduled for April 7.
The positive clinical readouts and defined regulatory path forward provide a near-term catalyst for Merck's stock. However, the market will continue to weigh the long-term commercial potential of these combinations against the looming patent cliff for its flagship product, setting the stage for a critical period of execution for the pharmaceutical leader.
