Drug Development

Pilot project provides a snapshot of effectiveness of Pfizer’s PARP contender talazoparib

Jennifer Litton, MD Anderson Cancer Center

Jennifer Litton, MD Anderson Cancer Center

You can expect some notable research updates on the slate of late-stage PARP inhibitors at this weekend’s annual European Society of Medical Oncology meeting. And an early teaser on what’s to come at ESMO should help whet everyone’s appetite for more.

Jennifer Litton, the principal investigator in the Phase III talazoparib study and an investigator at MD Anderson Cancer Center, set up a small pilot study that used the PARP inhibitor on a group of 13 breast cancer patients with BRCA mutations.

These patients were given the drug ahead of pre-surgical chemo, and Litton says her group tracked an average 78% tumor shrinkage among the women in the study. The full range extended from 30% to 98%.

“Acknowledging that this is a small study, I can’t think of any systemic therapy that gives results this consistently strong in only two months,” Litton said. A few weeks ago, Litton started an extension of the pilot, enrolling the first 6 of 20 patients who can shed further light on the drug’s use in treating breast cancer. And her group is using backing from MD Anderson’s Moon Shots program for the work, looking to quickly advance new therapies for cancer.

“If this study produces similarly strong results, the next step would be to directly compare talazoparib to chemotherapy in the pre-surgical, curative setting,” Litton added, “We might be able to delay or replace chemotherapy if we can get similar efficacy with less toxicity from treatment.”

That’s an intriguing piece of the puzzle for Pfizer $PFE, which agreed to pay $14 billion for Medivation to get its hands on Xtandi as well as the late-stage PARP drug. These drugs work by blocking a DNA repair pathway and there has been a considerable amount of research demonstrating their effectiveness as well as a relatively good safety profile.

The big show this weekend, though, will be reserved for Tesaro $TSRO and Clovis Oncology $CLVS, which both have closely-watched PARPs lining up for potential approvals. For Clovis, rucaparib presents its first real opportunity to gain a crucially important FDA approval. And Tesaro has been fueling high hopes with its own late-stage data set. Share prices on both companies have been soaring over the last few months.

We’ll keep you posted on the results.

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