Car-T cancer treatment

I don't know much about this but it seems like a new experimental treatment that is used for various cancers. I'm in a cancer forum for Multiple Myeloma and the say its far enough along to get approval in March. I have a friend with prostate cancer who was accepted into a study. They've already removed his T cells but he still waiting for the modified cells to come back and be reintroduced. I get the idea that for prostate cancer its still pretty early in studies. Anyone have experience with this, and for what type of cancer?