ESMO: Pfizer boosts Ibrance's class with positive neutropenia data

New data show neutropenia associated with CDK 4/6 use is "absolutely manageable," according to Pfizer.

MADRIDPfizer this week got some good Ibrance news, and it’s news that could benefit the med’s expanding class, too.

A subanalysis from the drug giant’s PALOMA-2 trial, presented at the European Society for Medical Oncology annual meeting, showed that neutropeniaobserved in 95.3% of the HR+, HER2- breast cancer patients enrolled in the studyis “absolutely manageable,” as Massimo Corsaro, Pfizer’s European senior medical director of oncology, put it in an interview.

While neutropenia is associated with an increased risk of infection, results showed that just 3.5% of Ibrance patients with neutropenia developed grade 3 or 4 infections. And only 1.8% of that group developed febrile neutropenia, a more serious condition.

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Results also showed that reducing dosage to treat patients’ neutropenia didn’t “compromise the efficacy” of Ibrance. “The benefit of the drug will be maintained even after adjusting the drug,” Corsaro said.

And the way he sees it, that’s a win for all CDK 4/6 inhibitors, a group comprising Ibrance along with Novartis’ Kisqali and Eli Lilly candidate abemaciclib.

The data “confirm that this class of drug is still working in a very fantastic way for the benefit of the patient,” he noted. And combining them with strong results abemaciclib posted over the weekend, “now we have even more certainty that this class of drug works not just by chance or coincidence,” he said. “Really the new data that are coming at this congress are really supporting what we already showed” with Ibrance.

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That’s not to say the meds don’t have different safety profiles. Kisqali comes along with some recommended ECG monitoring thanks to mild cardiac arrhythmias and one sudden death that appeared in trials. Abemaciclib, meanwhile, has produced high rates of diarrhea.

Both Novartis and Lilly say those issues are easy to manage; but while that may be the case, it’ll be hard to touch Ibrance thanks to a big first-to-market advantage. The med already boasted blockbuster status when Kisqali hit the scene in March, and Lilly is expecting its approval to arrive in the coming months after nabbing an FDA priority review in July.