Except that 1st. Sparks' stuff only cost a fraction of that to develop (closer to the $200M), and 2nd lot of the early expenses were fronted with tax payer's money.
And it my understanding that, soon gene therapy will be selecting which bits to flip and flipping them. It still needs testing, feedback, etc, but it isn't the same as going through a full development cycle. Am I wrong?
Doesn't seem to stand up to scrutiny, e.g. http://blogs.sciencemag.org/pipeline/archives/2017/10/18/dru... quotes $2bn as a more reasoned number.