[refurb]

Clinical trial failure rates (or inversely success rates) have been analyzed before.

https://www.nature.com/articles/nrd.2016.136

"They found that the probability of success was 63% in Phase I trials, 31% in Phase II trials, 58% in Phase III trials and 85% during the regulatory review process"

42% failure rates in phase 3 is enormously high. By then you've pretty much spent 90%+ of all the cost of getting a drug approved.

[FireBeyond]

But it's 42% of 19%. So out of 1,000 drugs, you're looking at 805 being ruled out before you even get to that "most expensive phase", which is my point. At Phase 3, you're looking at 113 succeeding, so you're "only" eating the really expensive[1] costs of Phase 3 for 82[2] of 1,000 attempts.

[1] Which isn't to say there's zero cost for Phase 1 or Phase 2, but it's a lot lot less than Phase 3 trials.

[2] 1,000 drugs, 63%, 630 of which make it through Phase 1. In Phase 2, 195 drugs, 31% of 630 succeed and make it through to Phase 3, and then 82 drugs (58% of 195) make it to regulatory approval.

[refurb]

Right, but with the cost distribution for clinical trials, costs increase by 4x in phase 2, then 8x in phase 3 (relative to phase 1).

So despite attrition that reduces candidates by 9x by phase 3, costs have increased by 8x.

[1]https://www.sofpromed.com/how-much-does-a-clinical-trial-cos...