Mateo J, Porta N, Bianchini D, et al. - Researchers attempt at prospective confirmation of the link between DNA damage response (DDR) gene aberrations and response to olaparib in metastatic castration-resistant prostate cancer in the TOPARP-B trial. Participants were selected from 17 UK hospitals. Random allocation (1:1) of patients with DDR gene aberrations was done to administer 400 mg or 300 mg olaparib twice daily, delivered continuously in 4-week cycles until disease progression or unacceptable toxicity. Findings revealed the antitumour activity of olaparib against metastatic castration-resistant prostate cancer with DDR gene aberrations, and therefore, genomic stratification of metastatic castration-resistant prostate cancer in clinical practice was supported. In 15 [31%] of 49 patients in the 300 mg cohort and 18 [37%] of 49 in the 400 mg cohort, the occurrence of anaemia was reported, which was the most common grade 3–4 adverse event in both cohorts. A total of 13 patients suffered 19 serious adverse reactions.