[choilive]

Everything is obvious in hindsight, but the data (and theory) at the time was that this had a really good shot at being the next big thing in a world where >90% of drugs never make it past clinical trials. 10% probability of success * $200B in lifetime sales (assuming a Keytruda level smash hit) means an EV of ~$20B or more. Not a surprise more than a few companies wanted a shot at it.

[doctorpangloss]

Actually a lot of drugs make it all the way through to approval from Phase I. I think you probably mean preclinical to approval. It's something like 33% across all therapy areas in the USA, and in some areas closer to 50%.