Pfizer stops late-stage Ibrance study early on positive results in metastatic breast cancer

Pfizer said Wednesday that a late-stage trial of Ibrance (palbociclib) will be stopped early, based on an assessment by an independent data monitoring committee, after hitting its primary endpoint of demonstrating an improvement in progression-free survival in certain women with metastatic breast cancer. The company noted that the data are "the first randomised Phase III trial results" for the CDK 4/6 inhibitor.

The PALOMA-3 study was designed to assess the safety and efficacy of Ibrance in combination with AstraZeneca's Faslodex (fulvestrant) versus Faslodex plus placebo in women with hormone receptor-positive, HER2-negative metastatic breast cancer following disease progression during or after endocrine therapy. Pfizer said that adverse events observed in the combination treatment arm were consistent with the known safety profiles of the individual drugs. The drugmaker added that full safety and efficacy data from the trial will be presented later this year at the American Society of Clinical Oncology annual meeting

"The results of this trial are especially important because they help us understand the potential of Ibrance to improve outcomes in patients with this difficult to treat cancer," remarked Mace Rothenberg, chief medical officer for Pfizer Oncology. Rothenberg indicated that Pfizer is "engaging in discussions with health authorities regarding a regulatory path forward" for Ibrance in this indication.

Ibrance was granted accelerated approval by the FDA in February, in combination with Novartis' Femara (letrozole), as a first-line treatment for women with advanced or metastatic oestrogen receptor-positive, HER2-negative breast cancer. Analysts estimate that the therapy could amass approximately $4 billion in revenue by 2020.

For related analysis, see ViewPoints: Pfizer sets out – earlier than expected – to show value of pipeline via Ibrance, and Physician Views Poll Results: Pfizer's Ibrance should be strong out the starting gates.

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