Well, how would someone else’s glioblastoma get in there? It was her tissue. No idea how or why the poliovirus didn’t attack healthy tissue.
Vaccinations work by hyping the immune system to attack the thing introduced by vaccination. Since the glioblastoma is in the brain, would the blood brain barrier be holding the immune system back from attacking the polio virus in the brain?
The virus is genetically engineered. Not only does it kill the tumor cells, but is causes the patient's immune system to attack the tumor cells also.