If you have hormone receptor-positive, HER2-negative breast cancer that has spread, and your disease has progressed while you were on a CDK4/6 inhibitor, there is a specific line in your pathology report that now matters more than it did a month ago.
It is the PIK3CA result. For years, a PIK3CA mutation was the finding that opened a door, because the targeted drugs in that pathway were built for mutated tumors. Roughly 60 percent of people in this situation do not have the mutation, and for them the pathway drugs were simply not options.
