Neuro,
But what if CX1739 turns out to be better for RD than CX1942? You just know that some enterprisng doctor and/or medical researcher will try it on their own. Then people could start using it for RD, too, although off-label, obviously. If I were a partner, I'd want to lock up both molecules or, at the very least, get an option on CX1739.
Bladerunner