New vaccine developed for cancer in children should it be used/trusted?

New use for mRNA is apparently treating difficult brain cancers in children. The mRNA vaccine can teach the sick kids cells to fight the cancer. These cancers are notoriously hard to treat because doctors can't use most chemo or radiation treatments. Do you thing this new vaccine is a good thing or should it be avoided?

https://theconversation.com/brain-cancer-in-children-is-notoriously-hard-to-treat-a-new-mrna-cancer-vaccine-triggers-an-attack-from-within-228666