The aims of this work were to characterize ipatasertib exposure–response (E‐R) relationships in a phase
II
study and to quantitatively assess benefit‐risk using a clinical utility index approach to support ipatasertib phase
III
dose selection in patients with metastatic castration‐resistant prostate cancer. Logistic regression and Cox proportional‐hazards models characterized E‐R relationships for safety and efficacy endpoints, respectively. Exposure metrics with and without considering dose interruptions/reductions (modifications) were tested in the E‐R models. Despite a steeper E‐R relationship when accounting for dose modifications, similar dose‐response projections were generated. The
clinical utility index
analysis assessed important attributes, weights, and clinically meaningful cutoff/tradeoff values based on predefined minimal, target, and optimistic product profiles. Ipatasertib 400 mg daily, showing the highest probability of achieving the minimal
product profiles
and better benefit‐risk balance than other doses (200–500 mg daily), was selected for further development in
metastatic castration‐resistant prostate cancer
.