Targeting your genes to treat prostate cancer

Written by Francesca Lake

A pioneering precision medicine could become the first of its kind to treat prostate cancer

Olaparib is a PARP inhibitor already licensed for use in germline BRCA-mutated ovarian and breast cancers. Now, this two-hitter has been turned on a third cancer, that of the prostate.

In the Phase II trial TOPARP-B, led by teams at The Institute of Cancer Research (ICR)  and The Royal Marsden NHS Foundation Trust (both London, UK), 98 men with pre-treated, advanced cancer and mutations in DNA repair genes such as BRCA1 and –2, PALB2, ATM and CDK12 were treated with olaparib. Half of the men received 300 mg and the other 400 mg, both twice daily. They were treated until disease progression, then followed every 3 months for life.

Of the men with BRCA mutations, over 80% responded and 40% were progression-free for over 1 year – the median overall survival was 17.7 months. For PALB2 mutations over half responded, and median survival was 13.9 months. Over a third of those with mutations in the ATM gene responded, and median survival was 16.6 months. The response rate in those with other DNA repair gene mutations was 20%.

The study followed TOPARP-A, which had tested olaparib in advanced prostate cancer and highlighted that there might be a benefit for patients with mutations in DNA repair genes.

“This study and another phase III trial place olaparib on the verge of becoming the first genetically targeted treatment in prostate cancer,” commented Johann de Bono, study leader (The ICR and The Royal Marsden NGS Foundation Trust). “I’m excited by these findings, and keen to see further research assessing how we can combine olaparib with other treatments to extend patients’ lives even more dramatically.”

The promise of this new treatment marks an interesting month for prostate cancer research, along with the recent announcement that a home test for prostate cancer could be on the horizon.