
Scientists have long known that a mutant form of the cell-signaling protein called KRAS causes cancer, but discovering drugs capable of blocking KRAS has proven difficult. The protein is spherical and nearly featureless — its structure has been compared to a tennis ball — leaving potential drugs with few, if any, effective attachment points.
On Wednesday, Amgen (AMGN) is reporting early but potential progress in an effort to block mutant KRAS and kill cancer cells. The Amgen drug, a small molecule pill called AMG 510, caused tumors to partially shrink in 30% of patients with lung tumors that tested positive for a particular kind of KRAS mutation.