Astellas Pharma and Pfizer have reported that their drug Xtandi (enzalutamide) enhanced overall survival (OS) in the Phase III ARCHES clinical trial in men with metastatic hormone-sensitive prostate cancer (mHSPC).

Xtandi is an androgen receptor inhibitor for oral use.

The randomised, double-blind, placebo-controlled Phase III trial assessed Xtandi plus androgen deprivation therapy (ADT) against placebo plus ADT in mHSPC patients.

The company-sponsored trial enrolled 1,150 subjects at study centres in the US, Canada, Europe, South America and the Asia-Pacific.

In the trial, the subjects were randomised to receive a daily dose of 160mg Xtandi or placebo and remained on a luteinising hormone-releasing hormone (LHRH) agonist or antagonist or had undergone bilateral orchiectomy earlier.

Radiographic progression-free survival (rPFS) was the trial’s primary goal while OS was the key secondary goal.

According to data from the trial, Xtandi plus ADT reduced mortality risk by 34% versus placebo plus ADT.

Median OS, signifying the time from randomisation to death due to any cause, was not attained in either treatment arm.

Furthermore, the safety profile in both trial groups was in line with the data from the primary analysis.

According to initial data from the trial reported in 2019, Xtandi plus ADT offered a 61% reduction in the risk of radiographic disease progression or death versus ADT alone in mHSPC patients, meeting the primary goal.

Grade 3 or greater adverse events (AEs) were also similar for subjects in both trial arms.

Common AEs of hot flushes, fatigue, arthralgia, hypertension, nausea, musculoskeletal pain, diarrhoea, asthenia and dizziness were observed more frequently in subjects receiving Xtandi plus ADT compared to the placebo arm.

In June 2021, Pfizer dosed the first subject in a Phase III TALAPRO-3 clinical trial of oral drug talazoparib plus enzalutamide in men with deoxyribonucleic acid damage response-deficient metastatic castration-sensitive prostate cancer.