AstraZeneca's Lynparza, now in hot PARP battle, posts 42% survival win in breast cancer

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AstraZeneca's Lynparza is currently competing against Clovis Oncology's Rubraca and Tesaro's Zejula in ovarian cancer.

CHICAGO—Back in February, AstraZeneca announced that its Lynparza had become the first PARP inhibitor to find success outside of ovarian cancer, posting positive results among breast cancer patients. And Sunday, the British drugmaker revealed just how positive those results were.

In a phase 3 study comparing the medication with standard-of-care chemo in patients with HER2-negative breast cancer and BRCA1 or BRCA2 mutations, Lynparza pared down the risk of disease worsening or death by 42%, AZ said at the American Society of Clinical Oncology annual meeting.

Tumors shrank in about 60% of patients treated with Lynparza, versus just 29% of those in the chemo arm of the study. And importantly, the med was “effective” among patients with triple-negative breast cancer, which has proven notoriously difficult to treat, said lead study author Mark Robson, of Memorial Sloan Kettering Cancer Center, in a statement.

Now, the British drugmaker is expecting a “change in medical practice” similar to the one it saw when Lynparza launched in ovarian cancer three years back, Michelle Werner, AstraZeneca’s U.S. head of oncology, said in an interview. “The ability to have an option that is not chemotherapy is also, I think, tremendous in terms of the potential that it has in being able to have a positive impact on a patient’s quality of life,” she added.

The data will also boost Lynparza over a pair of new PARP rivals in the ovarian cancer world: Clovis Oncology’s Rubraca, approved in December, and Tesaro’s Zejula, which won its FDA green light in late March. While both drugmakers are testing their meds in triple negative breast cancer, those studies are only in phase 2.

RELATED: AZ gears up for FDA filing as PARP inhibitor Lynparza wins big in ovarian cancer trial

Other data that could give AZ a lift? Results Lynparza posted last year, showing that in patients who’d relapsed after platinum chemo, Lynparza could hold off cancer recurrence for more than two years compared with placebo. After picking up a priority review for that use—as a maintenance treatment—the company is waiting for an FDA verdict on the new indication. Tesaro already has a thumbs up in that space.