A Phase II clinical trial led by The Institute of Cancer Research (ICR) in London and The Royal Marsden NHS Foundation Trust has shown that AstraZeneca’s olaparib could improve survival rates in prostate cancer patients.

Manufactured by AstraZeneca, olaparib is a poly (ADP-ribose) polymerase (PARP) inhibitor licenced for ovarian and breast cancer patients with BRCA mutations.

ICR researchers were the first to identify an approach to genetically target the drug.

The Phase II TOPARP-B study involved 98 advanced prostate cancer patients with mutations in DNA repair systems who previously received heavy treatment. The trial was conducted at 17 hospitals in the UK.

According to the results, more than 80% of patients experienced responses with the drug.

On average, participants who had DNA repair defects in their prostate cancers lived for more than 13 months, while those with BRCA mutations lived for about 18 months when treated with olaparib.

Overall, 47% of patients with the DNA repair defects had responses, with disease progression stopping for an average of 5.5 months. In addition, 40% did not progress for more than 12 months.

The median overall survival in patients with BRCA mutations was 17.7 months.

ICR cancer research professor Johann de Bono said: “Our trial has shown that men with prostate cancer who were selected for faults in DNA repair genes responded very well to the targeted drug olaparib, especially where they had BRCA mutations in their tumours.

“This study and another Phase III trial place olaparib on the verge of becoming the first genetically targeted treatment in prostate cancer.”

The TOPARP-B trial was funded by AstraZeneca, ICR, Prostate Cancer UK, the Prostate Cancer Foundation, Movember and the Experimental Cancer Medicine Centre (ECMC) Network.