Arm Z1F evaluated copanlisib, an α and δ isoform-specific phosphoinositide 3-kinase (PI3K) inhibitor, in patients with PIK3CA mutations (with or without PTEN loss)....The study met its primary end point with an ORR of 16% (P = .0341) with copanlisib showing clinical activity in select tumors with PIK3CA mutation in the refractory setting.