A personalized mRNA cancer vaccine developed by Moderna and Merck & Co has achieved its primary endpoints in a registration-enabling trial, marking a breakthrough in oncology treatment. The study, involving more than 1,000 melanoma patients, combined the experimental vaccine Intiseraman with Merck’s immunotherapy Keytruda, outperforming Keytruda alone in a late-stage trial for the first time.
The results, described as a "giant step forward" by Julie Gralow, chief medical officer of the American Society of Clinical Oncology, validate mRNA technology beyond its initial use in COVID-19 vaccines. Unlike conventional chemotherapy, the approach trains the immune system to recognize and target specific tumor mutations, offering a more precise therapeutic strategy. The combination therapy also demonstrated a favorable safety profile, with side effects comparable to those of influenza or COVID-19 vaccines, avoiding the severe complications sometimes associated with Keytruda alone.
The clinical success has triggered a sharp rally in Moderna’s shares, which surged more than 150% in intraday trading. The company faces significant revenue pressure following the collapse of its COVID-19 vaccine market, making this milestone critical for its long-term viability. For Merck, the development comes as Keytruda approaches a patent cliff later this decade, threatening one of the world’s top-selling drugs with biosimilar competition.
Analysts at Barclays estimate the combination therapy could generate annual revenue of approximately $3 billion in melanoma alone by 2035, assuming rapid regulatory approval. Patients may begin benefiting as early as next year if clearance is granted. The approach is already being tested in advanced trials for lung cancer and earlier-stage studies for bladder, kidney, pancreatic, and gastric cancers, expanding the potential market beyond melanoma.
Competitors are not far behind. BioNTech, which pioneered mRNA technology alongside Pfizer’s COVID-19 vaccine, is collaborating with Roche to develop a similar therapy for colorectal and pancreatic cancers. BioNTech has also announced plans to exit COVID-19 vaccine production in Germany, shifting manufacturing to its U.S. partner Pfizer to focus on oncology and infectious disease pipelines.
The choice of melanoma for the initial large-scale trial was strategic, as the disease exhibits a high mutation rate, making it more detectable by the immune system. Elizabeth Buchbinder, an oncologist at Mass General Brigham Cancer Institute, anticipates rapid advancements across multiple cancer types, noting that many tumors share similar mutational profiles. "This is an area poised for significant growth, especially now that these results are available," she said.
