AstraZeneca and MSD have announced positive results for their PARP inhibitor Lynparza (olaparib) in combination with abiraterone as a first-line treatment for metastatic castration-resistant prostate cancer (mCRPC) patients, with or without homologous recombination repair (HRR) gene mutations.

The results, from the PROpel Phase III trial, showed Lynparza plus abiraterone demonstrated a statistically significant and clinically meaningful improvement in radiographic progression-free survival (rPFS) versus standard-of-care abiraterone in the all-comers mCRPC patient population.

The independent data monitoring committee (IDMC) concluded that the trial met the primary endpoint of rPFS in men with mCRPC who had not received treatment in the first-line setting – including with new hormonal agents (NHAs) or chemotherapy.

Although the trial also showed a trend towards improved overall survival (OS) at the interim analysis, the data is still immature, with the trial set to continue in a bid to assess OS as a key secondary endpoint.

“We are encouraged by the PROpel results and the clinical benefit Lynparza in combination with abiraterone demonstrated versus abiraterone alone as a first-line treatment option for men with metastatic castration-resistant prostate cancer,” said Roy Baynes, senior vice president and head of global clinical development, chief medical officer, MSD Research Laboratories.

“Today’s results build on MSD and AstraZeneca’s commitment to bring Lynparza earlier in lines of treatment and to more patients with advanced prostate cancer,” he added.