New York, January 20, 2026, 14:02 EST — Regular session
- Merck shares hovered near $108.82 in afternoon trading, showing little movement
- Merck and Moderna released five-year melanoma results for their personalized vaccine paired with Keytruda
- Attention is turning to Merck’s Feb. 3 earnings call for fresh insights on the oncology franchise
Merck & Co (MRK.N) shares held steady on Tuesday following news that the company’s personalized cancer vaccine, developed with Moderna, continued to lower the risk of melanoma recurrence and death when used alongside Keytruda (pembrolizumab). By 2:02 p.m. EST, Merck was down just 0.01% at $108.82, with the stock fluctuating between $107.06 and $109.11. 1
Why it matters now: Keytruda stands as Merck’s top-selling drug, with crucial patents set to expire in 2028, tightening the timeline on what comes next for the company. Back in 2022, Merck told Reuters that Keytruda made up more than a third of its total sales. 2
Even when the stock lingers, a straightforward clinical update linked to Keytruda races through the tape. Investors hunt for combos that could extend the franchise’s reach into earlier-stage diseases and fresh tumor categories.
In a planned five-year follow-up of a phase 2b trial, the companies reported that the intismeran autogene-Keytruda combo slashed the risk of recurrence or death by 49% compared to Keytruda alone; the hazard ratio stood at 0.51. Recurrence-free survival — the length of time patients remain cancer-free — remained improved at the median five-year mark, they said. More data will be shared at an upcoming medical conference. The phase 3 adjuvant melanoma study is now fully enrolled, with other trials ongoing across multiple cancer types. Moderna’s Kyle Holen described the findings as “a prolonged benefit,” while Merck’s Marjorie Green called the five-year results “encouraging.” 3
Myles Minter, an analyst at William Blair, said intismeran showed an “impressive effect” compared to Keytruda alone but warned it’s too early to draw firm conclusions until the full dataset is released. The therapy works by decoding a patient’s tumor genetics and using mRNA instructions to direct the immune response, while Keytruda aims to keep immune cells active against cancer. According to the report, the most common side effects of intismeran were fatigue, injection-site pain, and chills. 4
The American Cancer Society projects roughly 112,000 new melanoma cases in the U.S. for 2026. This figure underscores why investors focus on long-term effectiveness in the adjuvant setting — and why confirming these results in larger trials is critical. 5
The work remains in progress. Late-stage trials often dampen early optimism, while customizing a shot for every patient introduces manufacturing and logistics challenges alongside the standard regulatory hurdles.
Merck faces its next major milestone on Feb. 3, when it will release fourth-quarter and full-year 2025 results. The company is also set to answer analyst questions about Keytruda demand, R&D expenses, and its pipeline. 6
