It was used in men with metastatic tumours that are castration-resistant (mCRPC), with or without a certain type of gene mutations called homologous recombination repair (HRR).
Abiraterone is the current standard of care for these cases.
The data also showed improved overall survival at an interim analysis, so the FTSE 100 group will carry out further studies to confirm that.
Prostate cancer is the second-most common cancer in men and despite an increase in the number of available treatments for men with mCRPC, five-year survival remains low.
“Today, men with metastatic castration-resistant prostate cancer have limited options in the 1st-line setting, and sadly often the disease progresses after initial treatment with current standards of care,” said Susan Galbraith, executive vice president at the Oncology R&D department.
“These exciting results demonstrate the potential for Lynparza with abiraterone to become a new 1st-line option for patients regardless of their biomarker status and reach a broad population of patients living with this aggressive disease.”
Shares rose 2% to 8,866p on Friday morning.