In the phase Ib, taselisib (supplied by Genentech, Inc.) was administered orally at a starting dose of 2 mg and escalated to 4 mg, 6 mg and 8 mg in a 3+3 trial design. This was in combination with 160 mg enzalutamide (supplied by Astellas Pharma, US) taken daily orally without interruption for a 28-day cycle. Patients were treated until disease progression or unacceptable toxicity. In phase II, patients received either 160 mg enzalutamide alone or 160 mg enzalutamide in combination with 4 mg taselisib orally, as prior phase I single agent testing of taselisib showed activity at 4 mg(21 (link)).