medwireNews: Supplementing androgen deprivation therapy (ADT) with enzalutamide delays radiologic progression in men with metastatic castration-sensitive prostate cancer (mCSPC), indicate phase III trial findings presented at the 2019 ASCO Genitourinary Cancers Symposium.
Over a median follow-up of 14.4 months in the double-blind ARCHES trial, the risk for radiographic progression or death was a significant 61% lower for the 574 mCSPC patients who were randomly assigned to receive enzalutamide 160 mg/day alongside ADT than for the 576 men instead given placebo plus ADT.
Median radiographic progression-free survival (PFS) was unreached for the enzalutamide group and was 19.45 months for the placebo group; the estimated 12-month event-free rates were 84% and 64%, respectively.
The radiographic PFS advantage afforded by enzalutamide was significant in most subgroups, including among participants with low and high volume of disease, and those who had or had not previously received docetaxel.
Enzalutamide was also associated with significant improvements relative to placebo in various secondary endpoints, namely objective response rate (83.1 vs 63.7%), time to prostate-specific antigen progression (hazard ratio [HR]=0.19), and time to initiation of new anticancer therapy (HR=0.28).
The overall survival data were not mature at the time of data analysis, but the HR favors enzalutamide, presenter Andrew Armstrong (Duke Cancer Institute, Durham, North Carolina, USA) told delegates in San Francisco, California, USA.
He added that these improvements in disease outcomes with enzalutamide did not come at the cost of increased toxicity or worse quality of life. The incidence of grade 3 or more severe adverse events was comparable in the enzalutamide and placebo arms, at 24.3% and 25.6%, respectively, and a corresponding 7.2% and 5.2% of patients discontinued treatment due to toxicity.
There were no significant differences between enzalutamide- and placebo-treated patients with respect to the total Functional Assessment of Cancer Therapy-Prostate score and time to deterioration of urinary symptoms, as assessed by the EORTC Quality of Life Questionnaire–Prostate Cancer Module.
“Following unblinding at the end of the double-blind treatment period and a statistically significant positive outcome from the primary endpoint analysis, eligible patients are being offered the opportunity to be treated with enzalutamide plus ADT in a pre-specified open-label extension,” Armstrong concluded.
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