Pfizer novel breast cancer drug gets FDA priority review

The US Food and Drug Administration (FDA) has accepted a New Drug Application (NDA) from Pfizer for its advanced breast cancer therapy palbociclib and granted it Priority Review status.

The drug is one of a new class of CDK 4/6 inhibitors and could be a potential blockbuster for Pfizer, with predicted sales of up to $10 billiion, according to analysts.

The submission seeks approval of palbociclib, in combination with letrozole, as a first-line treatment for postmenopausal women with oestrogen receptor positive, human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer who have not received previous systemic treatment for their advanced disease. It is based on the final results of phase II trial PALOMA-1, comparing palbociclib plus letrozole against letrozole alone in this population.

The Priority Review status accelerates the review time from 10 months to a goal of six months from filing and is given to drugs that may offer major advances in treatment or may provide a treatment where no adequate therapy exists.

Palbociclib received Breakthrough Therapy designation from the FDA in April 2013.

Pfizer recently initiated a multi-centre, open-label expanded access programme (EAP) in the US for palbociclib, making it available to post-menopausal women with hormone receptor-positive (HR+), HER2- advanced breast cancer who are eligible for letrozole therapy and for whom enrolling in other palbociclib clinical trials is not an option.

Palbociclib works by selectively inhibiting cyclin-dependent kinases (CDKs) 4 and 6 to regain cell cycle control and block tumour cell proliferation.

Two phase III studies of palbociclib in advanced/metastatic breast cancer have recently completed enrolment: PALOMA-2 evaluates palbociclib in combination with letrozole versus letrozole plus placebo, while PALOMA-3 evaluates palbociclib in combination with fulvestrant versus fulvestrant plus placebo in women with hormone receptor-positive (HR+), HER2- metastatic breast cancer whose disease has progressed after prior endocrine therapy.

Pfizer is not alone in this field. Others racing to develop their own CDK inhibitors include Eli Lilly, with its compound LY2835219, also known as bemaciclib, entering phase III trials this year and Novartis, with LEE011, which began phase III investigations at the end of 2013.


Pfizer’s novel breast cancer drug shows promise

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