Merck and Moderna are preparing to file their personalized mRNA cancer vaccine for approval after a Phase 3 trial showed it significantly delayed recurrence and metastatic disease in melanoma patients. The vaccine, given alongside Merck's immunotherapy Keytruda, marks a long-awaited breakthrough for a field that has struggled to deliver on its promise. One trial participant, teacher Gary Keblish, described the experience as a ride on the Magic School Bus, saying he is glad he went.
Now the companies face a broader question: can the vaccine work beyond melanoma? Moderna President Stephen Hoge said at the STAT Summit that they have "a lot of exploring to do." Merck's R&D chief Dean Li outlined a strategy built on years of Keytruda data. The pair will prioritize tumors where checkpoint inhibitors already work—so-called hot tumors with many mutations—and use the vaccine as an add-on after surgery, rather than chasing cold or metastatic tumors where Keytruda has failed.
Trials are already underway in adjuvant lung, kidney, and bladder cancer, with smaller studies in pancreatic and gastric cancer. The companies are also considering earlier-stage disease and patients whose metastatic tumors have been shrunk by other treatments. At the same time, they are analyzing immune data from thousands of patients in the Phase 3 program to improve the algorithm that selects up to 34 mutant proteins for each vaccine, hoping to make the technology more powerful and precise.