''These guys seem to be on the cusp of a cure for cancer.''
Sadly, that is not the case as there are a number of ways cancer cells can become immune to T-cells. Some of these are loss of target antigen(s), HLA, altered interferon or TNF-a signaling, and epigenetic. Some of the latter could be addressed with 5-azacitidine [1] or HDACi [2,3].