AstraZeneca PLC and Merck & Co. Inc. said Lynparza succeeded in extending the lives of certain prostate cancer patients without their disease worsening, meeting the primary goal in a late-stage study.

The phase 3 trial, known as PROfound, evaluated the efficacy and safety of Lynparza in treating patients whose castration-resistant prostate cancer had spread to other parts of the body and had the homologous recombination repair gene mutation, or HRRm.

These patients had their condition worsen even after receiving new hormonal anticancer treatments, including prostate cancer medicines Xtandi, or enzalutamide, by Japan's Astellas Pharma Inc. and Pfizer Inc., and Johnson & Johnson's Zytiga, also known as abiraterone.

Results showed that Lynparza helped patients with mutations in their BRCA1/2 or ATM genes live longer without radiographic progression, compared to Xtandi or Zytiga.

AstraZeneca said PROfound's full data will be presented at a forthcoming medical meeting.

Lynparza, or olaparib, belongs to a class of medicines known as PARP inhibitors, which work by preventing the PARP protein in cancer cells from repairing their damaged DNA, causing the cancer cells to die.

The drug is already approved as maintenance therapy for certain ovarian cancer patients in the EU, U.S. and Japan. In the U.S., Lynparza is also approved to treat patients with BRCA-mutated breast cancer.

The companies intend to explore additional trials for Lynparza in prostate cancer, including the ongoing PROpel phase 3 study evaluating a combination of Lynparza and Zytiga as the initial treatment of castration-resistant prostate cancer that has spread across the body.

U.K's AstraZeneca and Kenilworth, N.J.-based Merck are developing Lynparza under an $8.5 billion collaboration agreement signed in 2017.