Trial data, however, raised doubt about Lynparza's benefit in metastatic castration-resistant prostate cancer patients with non-BRCA1/2 HRR gene mutations.
After five years, nearly half the Lynparza-treated patients in the SOLO-1 trial remained disease-free, compared with one-fifth of those who received placebo.
Patients on the combo regimen had similar outcomes to those on monotherapy, but researchers said that the benefit seen in certain groups should be explored in randomized trials.
The approval will make Merck and AstraZeneca's Lynparza available to patients in the EU who have not progressed after 16 weeks on platinum-based chemotherapy.
With studies showing BRCA-mutated patients have a greater magnitude of benefit, oncologists grapple with complex treatment decisions in BRCA mutation-free cases.
The agency based its decision on the results of the POLO trial, in which patients on olaparib had a median progression-free survival of 7.4 months compared to 3.8 months on placebo.
