Moderna and Merck’s mRNA Cancer Therapy Cuts Melanoma Recurrence Risk by Half in Five-Year Study
Cambridge, Tuesday, 20 January 2026.
New five-year data reveals the personalized mRNA vaccine combination reduces melanoma recurrence or death risk by 49%, demonstrating sustained efficacy over standard immunotherapy alone.
Long-Term Efficacy in Personalized Oncology
On Tuesday, January 20, 2026, Moderna (MRNA) and Merck (MRK) released pivotal five-year follow-up data from their Phase 2b KEYNOTE-942 study, marking a significant milestone in the field of personalized neoantigen therapy [1][2]. The data indicates that the investigational mRNA cancer vaccine, intismeran autogene (mRNA-4157), when administered in combination with Merck’s immunotherapy drug Keytruda (pembrolizumab), reduced the risk of recurrence or death by 49% in patients with high-risk stage III/IV melanoma following complete resection compared to Keytruda alone [1][2]. This sustained improvement, characterized by a hazard ratio of 0.510, underscores the potential durability of training the immune system to target specific tumor cells over an extended period [1][4].
Consistency Across Clinical Benchmarks
Analytically, the five-year data demonstrates remarkable consistency with earlier readouts, suggesting that the immunological benefit of the vaccine does not wane quickly [3]. In a previous analysis at the three-year mark reported in December 2023, the combination therapy also showed a 49% reduction in the risk of recurrence or death [3]. This follows the primary analysis conducted at approximately two years, which had initially shown a 44% reduction in risk [3]. The ability of the treatment to maintain a reduction in recurrence risk of nearly half over five years highlights the potential of mRNA technology to provide prolonged protection in an adjuvant setting [1][3].
Market Reaction and Corporate Developments
The announcement coincides with a period of strong market performance for Merck, which has seen its stock value climb nearly 39% over the past six months, resulting in a market capitalization of approximately $270 billion [4]. In parallel legal developments beneficial to the partnership, the European Patent Office’s Board of Appeal revoked a key patent held by Arbutus Biopharma Corporation on January 19, 2026, following opposition from Moderna and Merck [4]. This legal victory removes a potential intellectual property hurdle for the mRNA technology platform used in intismeran autogene [4]. Furthermore, as of January 19, 2026, Merck is reportedly in discussions to acquire Revolution Medicines, signaling continued aggressive expansion in its oncology portfolio [4].