evidence: As stunningly successful as the mRNA COVID-19 vaccines have been, researchers have long hoped to use mRNA vaccines for a very different purpose—to treat cancer. mRNA-based cancer treatment vaccines have been tested in small trials for nearly a decade, with some promising early results. In fact, scientists at both Pfizer-BioNTech and Moderna drew on their experience developing mRNA cancer vaccines to create their coronavirus vaccines. Now, some investigators believe the success of the mRNA COVID-19 vaccines could help accelerate clinical research on mRNA vaccines to treat cancer. [...] Another key feature of the Pfizer-BioNTech and the Moderna coronavirus vaccines is the use of modified forms of mRNA, according to Jordan Meier, Ph.D., of NCI’s Center for Cancer Research, who studies mRNA modifications.