Question special

I want to follow up on Dr. Levy's answer to my question yesterday re: cancer genomics and using specific drugs to target specific genetic profiles. This is clearly a promising hope for cancer patients. There are lots of potential druggable targets in cancers' biological pathways, though! How personalized can genomic-based cancer treatment get, given the realities of drug development funding, FDA approval via adequate patient sample sizes, etc? Is there a point when personalized medicine becomes financially or logistically untenable? How are academic and industry researchers working around this issue?