There are clinical trials on Glioblastoma CAR-T treatment but it faces the same problems as any other solid tumor - namely the solid tumor microenvironment is not amenable to the current generation of CAR-T treatments

In addition one of the dreaded side effects of CAR-T is neurotoxicity. CAR-T can cross the blood-brain barrier and leads to inflammation in the brain. You can treat it pretty quick with steroids but this side effect along with several other pro-inflammatory ones is the reason for the 30 day hospitalization sp treatment.

Not CAR-T or CRISPR AFAIK, but there's been some recent breakthroughs with getting treatments past the blood brain barrier, and promising glioblastoma treatments are in the pipeline as well. This is just what I've seen on the internet news, you'd find more than I know about it with some internet searches.

I hope you aren't affected by GBM. If you are, or someone you know is, my only advice is to live life to the fullest while you can and don't let yourself fall into denial of the prognosis.