What an mRNA melanoma vaccine may mean for cancer treatment

Moderna and Merck recently announced results from a phase 3 clinical trial showing that a new personalized mRNA vaccine, when combined with the drug pembrolizumab (Keytruda), significantly reduced recurrence rates of melanoma in patients. Dr. Michael Postel, Chief of the Melanoma Service at Memorial Sloan Kettering Cancer Center, whose patients were part of the trial, explains that this marks the first time a cancer vaccine has been made on a personalized basis — with each patient's own tumor serving as the source for vaccine creation. "This is the ultimate personalized medicine," he says.

How the personalized vaccine works

The vaccine is built on a straightforward but technically demanding principle: each person's tumor is genetically unique, and the goal is to train the patient's own immune system to recognize and destroy cells carrying that specific tumor's signature. Here is how it works step by step. After a patient's melanoma is surgically removed, the tumor's DNA is sequenced. A computer algorithm then analyzes the mutations present and identifies which ones are most likely to trigger a productive immune response — not all mutations are equally useful for this purpose. Based on that analysis, an mRNA construct is manufactured specifically for that individual patient. When injected, it instructs the patie