Pfizer's Ibrance misses shot at big new market with early breast cancer failure

Pfizer’s Ibrance has met with immense success in metastatic breast cancer since breaking onto the scene in 2015. But its first foray into early breast cancer was a bust, the company reported late Friday.

In a result that could cost Ibrance access to a multibillion-dollar market, a planned futility analysis of the phase 3 Pallas trial determined adding the drug to standard postsurgery endocrine therapy was unlikely to significantly lengthen patients’ time before invasive disease returned. The trial tested Ibrance in women and men with HR-positive, HER2-negative early breast cancer.

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The independent data monitoring committee's conclusion was “a surprise and disappointment,” as RBC Capital Markets analyst Randall Stanicky put it in a note to clients, and investors agreed, sending Pfizer shares down by about 7% in after-market trading.

The company has for years been talking up Ibrance’s potential to move earlier into therapy and unlock a big new commercial opportunity; back in 2017, Morgan Stanley analyst David Risinger pegged the adjuvant opportunity at $8 billion-plus.

In the wake of the failure, investors will have to pin their hopes on another trial—dubbed Penelope-B—testing the drug in patients with a high risk of recurrence after pre-surgery chemo. That study, which began enrolling patients about two years earlier than Pallas, is still ongoing, Stanicky noted, adding that “in theory, we would expect more events to have occurred in the higher-risk patient subgroup,” indicating that trial may be going better.

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Those results will be along later this year, but while they might ease the sting of the Pallas flop, they won’t erase it completely. The high-risk group represents “a smaller commercial opportunity” relative to the Pallas population, Stanicky pointed out.

Ibrance currently bears a U.S. approval, when coupled with an aromatase inhibitor, to treat postmenopausal women or men with HR-positive, HER2-negative metastatic breast cancer who haven’t yet received other hormone therapy. Paired with fulvestrant, it’s cleared to treat patients whose disease has progressed after hormone therapy.

Thanks to those indications, the drug racked up $3.25 billion in U.S. sales last year despite in-class competition from Novartis’ Kisqali and Eli Lilly’s Verzenio. Worldwide, Ibrance’s 2019 sales hit $4.96 billion.