Pfizer breast cancer drug delivers

A Phase III study on Pfizer’s treatment Ibrance in combination with hormone therapy has revealed the drug more than doubled the duration of disease control for women with breast cancer.

Unveiled at cancer conference ASCO which is currently underway, the positive data backs up last month’s decision by US regulators to end a trial early on the drug due to its impressive results.

Adding Ibrance (palbociclib) to AstraZeneca‘s Faslodex (fulvestrant) has shown to more than double progression-free survival time, holding off breast cancer advancement by around 5 months in women with previously treated, estrogen-receptor-positive but HER2-negative forms of the disease.

This category accounts for about 75% of all breast cancers, and at the time of the interim analysis the average time to disease progression was 9.2 months – compared with 3.8 months in the placebo arm.

Ibrance was given conditional approval by the FDA in February for patients who had not previously been treated for advanced breast cancer.

“The results of [trial] PALOMA-3 are compelling and provide evidence that could potentially expand the role of palbociclib as an innovative first-in-class therapy for patients with metastatic breast cancer,” says Dr Mace Rothenberg, senior VP and chief medical officer for Pfizer Oncology.

On the back of such pleasing results the US pharma giant is in discussions with regulatory authorities to determine next steps to potentially make it available for women with HR+, HER2- metastatic breast cancer – whose disease has progressed following endocrine therapy.

Ibrance blocks two enzymes, cyclin-dependent kinase 4 and 6, which are involved in growth of cell. According to analysts at Wall Street the drug could lead to annual sales of over $5 billion.

Pfizer intends to file a marketing authorisation application for Ibrance to the European Medicines Agency in the second half of 2015, and in addition will be aiming towards an FDA data review in order to eventually hit the US market.

Brett Wells

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