Pfizer’s Medivation breast cancer PARP boosts PFS in phase 3

An experimental PARP med bought up as part of Pfizer’s multibillion-dollar Medivation buyout performed well in a late-stage trial as the Big Pharma eyes regulatory filings.

PARP became all the rage back in 2016 with some stellar data and a series of approvals, partially beating out other I-O and gene editing tech for column inches.

The immediate win for Pfizer in its $14 billion deal to snap up Medivation was the blockbuster cancer drug Xtandi, but its pipeline was also a selling point; today, one of those later projects is looking as if it may come good.

Talazoparib, originally a BioMarin drug before being sold to Medivation in 2015, is an oral, once-a-day PARP inhibitor being tested in the so-called EMBRACA study in a specific set of patients, namely those with germline (inherited) BRCA1/2-positive (gBRCA+) locally advanced and/or metastatic breast cancer (MBC).

The data show superior progression-free survival (PFS) in patients treated with the drug when pitted against those who received chemo. Median PFS was 8.6 months for patients on talazoparib, while those on chemo saw 5.6 months. “This represents a 46% reduction in the risk of disease progression,” Pfizer said in a statement.

The Big Pharma adds that the proportion of patients achieving a complete or partial response (known as an objective response rate) in the talazoparib group was more than twice that of the control arm (62.6% for talazoparib vs. 27.2% for chemo).

Pfizer says it will now “be discussing these data from EMBRACA […] with worldwide health authorities.”

Pfizer will hope to get its med into an increasingly busy market that already has AstraZeneca’s Lynparza, Tesaro Zejula and Clovis’ Rubraca vying for position.

And back in February, AstraZeneca rolled out phase 3 results showing that Lynparza could also top standard-of-care chemo at increasing progression-free survival in patients with HER2-negative breast cancer and BRCA1 or BRCA2 mutations. Game on for both (and with a hint of irony, given that Pfizer could have owned Lynparza if it had managed to buy AstraZeneca a few years back). 

Mace Rothenberg, M.D., chief development officer, Oncology, Pfizer Global Product Development, said: “Results from the EMBRACA study are very encouraging and a great example of precision drug development. By enrolling only patients with germline BRCA-positive metastatic breast cancer, treatment with talazoparib reduced the risk of disease worsening by nearly half, compared with current standard of care chemotherapy. This includes heavily pretreated patients, those with hormone receptor-positive disease and those who had a history of brain metastases.”

But there have been setbacks in this area for some, with AbbVie recently revealing that its PARP inhibitor veliparib flunked two late-stage tests in non-small cell lung cancer and triple negative breast cancer.

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