IPATential150: ipatasertib plus abiraterone and prednisolone in metastatic castration-resistant prostate cancer

A randomised, double-blind phase 3 trial at 200 sites in 26 countries in men with previously untreated asymptomatic or mildly symptomatic metastatic castration-resistant prostate cancer with progressive disease. Of 1,611 men screened, 1,101 were enrolled and randomised to ipatasertib 400 mg daily with abiraterone and prednisolone or to placebo with abiraterone and prednisolone, stratified by prior taxane, type of progression, visceral metastasis and tumour PTEN-loss status by immunohistochemistry. In the 521 men, 47%, whose tumours showed PTEN loss by immunohistochemistry, median radiographic progression-free survival was 16.5 months with placebo and 18.5 months with ipatasertib, hazard ratio 0.77, significant at the prespecified alpha. In the intention-to-treat population the difference was 16.6 against 19.2 months, hazard ratio 0.84, not significant at its alpha. Grade 3 or higher adverse events occurred in 39% of the placebo group and 70% of the ipatasertib group, with discontinuation for adverse events in 5% against 21%.