Merck shares jump 4% on KEYTRUDA-WELIREG trial win in kidney cancer
28% reduction in disease recurrence opens $6 billion market opportunity as Merck plans life after KEYTRUDA patent expiry
Merck & Co shares surged 3.8% on Friday after the pharmaceutical giant announced positive Phase 3 trial results showing its KEYTRUDA cancer drug combined with newer therapy WELIREG significantly reduced the risk of disease recurrence in kidney cancer patients, opening a potential $6 billion market opportunity.
The pivotal LITESPARK-022 trial met its primary endpoint, with KEYTRUDA plus WELIREG reducing the risk of disease recurrence or death by 28% compared to KEYTRUDA monotherapy in patients with clear cell renal cell carcinoma following kidney removal surgery. At a median follow-up of 28.4 months, the 24-month disease-free survival rate was 80.7% for the combination therapy versus 73.7% for KEYTRUDA alone, with a hazard ratio of 0.72 that was statistically significant (p=0.0003).
"The results mark the first positive Phase 3 trial for WELIREG in earlier-stage disease and the first study in earlier-stage cancer to demonstrate a disease-free survival improvement compared to KEYTRUDA monotherapy," Merck stated in its press release.
The U.S. Food and Drug Administration has already accepted supplemental applications for priority review, setting a target decision date of June 19, 2026. The trial enrolled 1,841 adult patients at increased risk of recurrence after nephrectomy, representing a significant expansion into earlier-stage disease treatment.
The market opportunity is substantial. Leerink Partners analysts estimate that an approval of the WELIREG-KEYTRUDA combination in adjuvant clear cell RCC could increase Merck's annual U.S. revenue opportunity in the indication from $2.3 billion to $6.3 billion, according to analysis published in Fierce Pharma. The combination could allow WELIREG to "inherit the large market currently served exclusively by KEYTRUDA," the analysts noted.
The trial success represents a critical strategic milestone for Merck as it navigates the approaching loss of exclusivity for KEYTRUDA, its flagship immunotherapy that generated $31.7 billion in global sales during 2025. KEYTRUDA faces patent cliffs beginning in 2028, creating urgency for Merck to demonstrate it can sustain growth through new combinations and expanded indications.
"These two Phase 3 successes for WELIREG should inspire investor confidence in Merck post-Keytruda," Leerink analysts wrote. Merck CEO Robert Davis has previously stated the company expects to benefit from "approximately 20 additional new growth drivers in the coming years, almost all of which have blockbuster potential."
WELIREG, which targets hypoxia-inducible factor-2α (HIF-2α), has shown strong growth momentum. The drug generated $220 million in fourth-quarter 2025 sales, up 37% year-over-year, with total 2024 sales reaching $509 million. Its current approval is for previously treated advanced renal cell carcinoma patients, but the adjuvant setting represents a much larger commercial opportunity if approved.
The global kidney cancer drug market was valued at $5.65 billion in 2024 and is projected to reach $7.59 billion by 2033, growing at a 3.3% compound annual rate, according to market research. For advanced RCC specifically, the market is forecast to grow from $9.6 billion in 2024 to $15.1 billion by 2030, representing a 7.8% CAGR.
Merck stock, which gained 51.8% over the past year, now trades at $123.82 with a market capitalization of approximately $298 billion. Analysts have an average target price of $126.57, with 16 buy ratings and 12 holds among covering firms, according to market data. No analysts currently rate the stock a sell.
The safety profile in the LITESPARK-022 trial was consistent with previous studies, though grade 3 or higher treatment-emergent adverse events occurred in 52.1% of patients receiving the combination versus 30.2% for KEYTRUDA alone. The most common severe side effects in the combination arm were anemia (12.1%), increased liver enzymes (6.4%), and hypoxia (4.6%).
Merck also presented positive results from a separate Phase 3 trial, LITESPARK-011, evaluating WELIREG combined with Eisai's LENVIMA in previously untreated advanced RCC. However, analysts noted that trial "may be less clearly positive" due to missing overall survival data and potential toxicity concerns.
The company has implemented a cost-cutting campaign aimed at saving $3 billion annually by the end of 2027, including approximately 6,000 job cuts, as it seeks to position itself for sustainable growth beyond the KEYTRUDA era. The WELIREG combination successes provide investors with tangible evidence that Merck's pipeline diversification strategy is gaining traction.