New Drugs Could Treat Half of Prostate Cancers

A new class of cancer fighting drugs that seems to hold promise in treating breast cancer may also work with certain types of prostate cancer. Those are the findings of a new University of Michigan (U-M) study.

About half of prostate cancers cause two genes to bind together in what's called "gene fusion." New chemotherapy drugs are being shown to shrink prostate cancer tumors and block them from spreading.

New drugs may treat half of all prostate cancers.

“This type of gene fusion occurs in about 50 percent of prostate cancers, but the genes involved have been notoriously difficult to target therapeutically," says Arul Chinnaiyan, M.D., Ph.D., director of the Michigan Center for Translational Pathology and S.P. Hicks Professor of Pathology at the U-M Medical School.

So instead of treating the gene fusion directly, the researchers found they could go after a close partner. The drug Olaparib is being tested because it  inhibits, or blocks a particular enzyme (PARP) involved in DNA repair.

This class of drugs, called PARP inhibitors, is also being tested and shows promise in breast cancer patients who have mutations in the BRCA1 and BRCA2 genes. About 10 percent of all breast cancers have these genetic mutations.

Researchers worked with prostate cancer models in cell lines and mice. They found that Olaparib worked to shrink tumors that had the TMPRSS2:ERG gene fusion. The therapy also blocked the ability of the tumors to spread.

Olaparib did not affect tumors that didn't have this particular gene fusion.