ESMO: Pfizer's narrow Ibrance survival miss could still sway doctors in its favor, executives say

Pfizer's Ibrance, in combination with fulvestrant, showed it could extend patients' lives by nearly seven months over fulvestrant-plus-placebo. (Pfizer)

MUNICH—Pfizer’s Ibrance may have narrowly failed to show it could help relapsed breast cancer patients live longer. But executives contend its newest results still make a “compelling” case.

In a phase 3 study dubbed Paloma-3, HR-positive, HER2-negative breast cancer patients in the Ibrance-plus-fulvestrant arm lived a median 34.9 months—nearly seven months longer than the median 28 months recorded in the fulvestrant-only group, Pfizer said at the European Society for Medical Oncology annual meeting. But that difference came just shy of the statistical significance mark.


Pfizer Oncology Global President Andy Schmeltz was quick to echo the points Pfizer made when it released top-line data in June—namely, that overall survival was a secondary endpoint of the trial, which focused on women whose cancer had progressed after endocrine therapy.

“The primary endpoint, progression-free survival … was met a while ago, and that’s what the study was powered for,” he said.

He also pointed to the “stringent statistical criteria for significance,” noting that Ibrance “just barely missed.”

“Particularly in breast cancer, more than other types of cancer, it’s challenging to demonstrate overall survival because of the course of the disease. It’s slower than other types of tumors,” meaning that doctors can put patients on other therapies after the Ibrance regimen, confounding the measurement of overall survival.

The way he sees it, the showing “really reinforces that the best chance to delay the disease and to extend survival for women with metastatic breast cancer is this combination.”

Plenty of doctors are likely to agree. The Ibrance-fulvestrant combo picked up its FDA approval back in February 2016, and it’s racked up nods in more than 80 countries around the world. All told, 160,000 women have been treated with Ibrance since it first hit the market, Schmeltz said.

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Still, a fair share of patients don’t receive the blockbuster, and that’s what Pfizer’s hoping the new data can help change. For doctors “who aren’t quite there yet,” the new results provide “yet further evidence” of Ibrance’s utility, he said.

Meanwhile, Pfizer is already looking ahead to the next frontier for Ibrance, which is facing down relatively new challengers in Eli Lilly’s Verzenio and Novartis’ Kisqali. The company is testing Ibrance in early breast cancer, and it expects to see those studies begin to read out over the next year and a half.

Earlier Ibrance use “could even prevent and delay the metastases, which would be a game-changer for women with breast cancer,” Schmeltz said, adding, “we’re excited for the future.”