Breast cancer drug may aid prostate

AstraZeneca’s Lynparza medicine helped men with a lethal but uncommon form of prostate cancer in a study, opening a potential new use for a drug cleared for breast and ovarian cancers.

The medicine was successful in a final-stage test of metastatic castration-resistant prostate cancer. Patients’ tumors also had specific gene mutations and had failed to respond to other treatments, according to a statement from Astra and Merck & Co., its partner in developing the drug.

The study widens the potential uses for Lynparza, a drug that attacks tumors by thwarting the repair mechanisms of cells with certain gene flaws, rendering them unable to grow. The treatment, already used for breast cancer, has appeared promising in other malignancies, including a specific form of pancreatic cancer.

Analysts project about $1 billion in Lynparza sales for the year. Key to its prospects are the results of trial, due later this year, that tests the drug in a wide population of ovarian cancer patients, said Sam Fazeli, a Bloomberg Intelligence analyst.

Prostate cancer is the second-most common form of the disease in men, and the category shown to be treated by Lynparza is quite deadly, as about only 30 percent of patients live five years after diagnosis. Yet it occurs in a relatively small portion of patients.

Doctors sometimes suppress male hormones that can drive the growth of aggressive prostate cancers, lowering them to a point equivalent to castration. The approach doesn’t always work: in a 2012 study, prostate cancer continued to grow in about 28 percent of U.K. men getting this level of treatment.

The Lynparza study also focused on patients with gene mutations that interfere with tumors’ DNA repair. These are found in more than one in four men with the spreading, castration-resistant form of the disease, Astra said.

The trial “demonstrates the potential value of genomic testing in this at-risk patient population,” Jose Baselga, Astra’s executive vice president for oncology, said in the statement.