Moderna and Merck announced on August 19 that their personalized mRNA cancer vaccine Intismeran showed positive results in a Phase 3 trial targeting melanoma [1, 2, 3]. The vaccine is given alongside Merck’s monoclonal antibody Keytruda after surgical removal of stage IIB-IV melanoma tumors [1, 2, 3].
The trial enrolled 1,137 patients with high-risk or advanced melanoma whose tumors had been removed surgically [1, 3]. The combination of Intismeran and Keytruda significantly extended recurrence-free survival and distant metastasis-free survival compared to Keytruda alone [1, 3].
Intismeran works by encoding up to 34 unique mutations from each patient’s tumor to train the immune system specifically to target residual cancer cells [1, 2, 3]. A prior 5-year Phase 2 trial showed the vaccine reduced the risk of recurrence or death by 49% and the risk of distant metastasis or death by 59% [1].
The vaccine was generally well tolerated, with side effects similar to routine vaccines, said Dr. Jane Healy, Merck’s head of oncology early development [3]. Moderna’s shares surged up to 160% after the announcement, reflecting investor enthusiasm [2].
Karen Knudsen, CEO of the Parker Institute for Cancer Immunotherapy, called the results "an auspicious start" marking the next phase in immunotherapy [2]. Moderna President Stephen Hoge said thousands of patients could benefit by next year if regulators approve the treatment [2].
The companies plan to present detailed data from the Phase 3 trial at an upcoming international medical meeting [1, 2, 3]. They are also in discussions with regulators about potential approval for widespread use in high-risk melanoma patients [2, 4, 3].
