 This research suggests that clonal multiple PIK3CA mutations are associated with increased sensitivity to P110-alpha inhibitor treatment in HR+, HER2, metastatic breast cancer. The findings provide evidence for the potential use of P110-alpha inhibitors alone or in combination with other targeted therapies in breast cancer and possibly other solid tumors. This article was authored by Catherine E. Hutchinson, Jessica W. Chen, Heidi M. Savage, and others.