Carving out RAS mutant populations from approved EGFR antibodies after initial approval was difficult due to resistance from developers and regulators.

“An attempt then to carve out the RAS mutant population from an approved epidermal growth factor receptor antibody was a ground war that took years and years. The number of constituents, first the drug developer themselves, and regulators joining them who stood in the way of the most obvious scientific hypothesis I've ever seen in my academic career.”