This is the latest, hottest topic in cancer research. I don’t know if you’ve heard about it, but an mRNA vaccine against a person’s own pancreatic cancer cells has preliminarily shown 50% efficacy (meaning no relapse at 18 months in 50% of the people treated), which is a HUGE response, when you consider that current treatments have a less than 5% success rate, and most people are dead within a year of diagnosis.
I would say that she should apply wherever she wants. She has the academic credentials and the references. She has already demonstrated that she is a capable bench researcher. If her current interest is cancer-fighting immunology, she should get a job in a lab doing that, if at all possible, but I don’t think that it would be held against her that her current biotech research job does not exactly match her PhD interest.