ZURICH: Roche had mixed results for a late-stage trial of an experimental drug for prostate cancer, the Swiss drugmaker said on Friday, missing its goal in the overall population but cutting risk of disease worsening in patients with mutated tumours.

Roche is testing ipatasertib against metastatic castration-resistant prostate cancer (mCRPC), including in patients whose tumours have losses of the proteins phosphatase and tensin homologue, or PTEN losses, that are associated with worse outcomes for patients.

For the overall group of patients in its Phase III IPATential150 study, Roche said ipatasertib did not meet its goal of boosting radiographic progression-free survival (rPFS), a key goal in mCRPC.

However, for those patients whose tumours had PTEN losses, the drug provided a statistically significant reduction in the risk of disease worsening or death, compared to patients who got the standard of care, plus a placebo, the company said.

Around 50% of patients with metastatic castration-resistant prostate cancer, labelled such because it advances even with hormone depletion therapy, may have functional losses of PTEN protein that suppresses the tumour.

Consequently, Roche called the result of the trial "encouraging" and said it would press ahead until the next planned analysis.

Prostate cancer is the second most frequent cancer and the fifth leading cause of death in men, according to global cancer statistics compiled in a 2018, study.

"The early results of the IPATential150 study are encouraging in our ongoing mission to develop new treatment options for people with advanced prostate cancer," Roche Chief Medical Officer Levi Garraway said in a statement.