Results from of phase 3 clinical trial, presented at the European Society of Medical Oncology conference this week showed that Lynparza (olaparib) effective in delaying the progression of disease in men with both metastatic castrate-resistant prostate cancer and mutations in their homologous recombination repair, or HRR, genes.
Olaparib, manufactured by AstraZeneca, is already used to treat cancers including ovarian, fallopian tube or primary peritoneal cancer, as well as certain types of breast cancer.
The trial included 387 patients and involved giving either olaparib or other drug treatments to patient with castration-resistant prostate cancer and HRR gene mutations.
The results showed that Lynparza improved progression-free survival an average 7.4 months compared with 3.6 month for men treated with one of other drugs, includig hormone therapy enzalutamide, sold under the brand name Xtandi, or the hormone-based chemotherapy abiraterone, sold under the brand name Zytiga.
"This is a landmark trial and potentially practice-changing for men with advanced metastatic castration-resistant prostate cancer--the deadly phase of the disease," said Maha Hussain, MD, the first author of the study. Hussain is the deputy director of the Robert H. Lurie Comprehensive Cancer Center at Northwestern University Feinberg School of Medicine in Chicago.
As CNN reported, most people think of BRCA gene mutations as causing breast and ovarian cancer, but researchers have long known that several cancers other than breast and ovarian are associated with harmful mutations in BRCA1 and BRCA2 genes, including prostate cancer.
"We've known for some time that BRCA mutations play a role in prostate cancer and specifically an increased risk of developing prostate cancer and an increased risk of more aggressive prostate cancers," said Dr. Brandon Mahal at the Dana-Farber Cancer Institute in Boston, who has studied treatments for prostate cancer but was not involved in the new trial.
"The frequency that they occur is still a low percentage of patients with prostate cancer -- less than 5%," Mahal told CNN.. "But the reason it's important is because there's an enzyme called the PARP enzyme that is involved in DNA repair. If there's a mutation in a DNA repair gene, like a BRCA mutation, then those cells may be more responsive to drugs like PARP inhibitors that block that PARP enzyme." Lynparza is a PARP inhibitor.
Source; CNN, September 30