Pfizer's experimental drug palbociclib receives FDA breakthrough status for breast cancer

Pfizer announced Wednesday that its experimental oral cyclin-dependent kinases 4 and 6 inhibitor palbociclib received breakthrough therapy status from the FDA for the treatment of breast cancer.

The company noted that the designation was based on preliminary Phase II data in which palbociclib in combination with Novartis' Femara (letrozole) achieved a progression-free survival of 26.1 months, compared to 7.5 months for letrozole alone. The drugmaker added that it has initiated a Phase III trial of palbociclib plus letrozole for the first line treatment of oestrogen receptor-positive, HER2-negative advanced or metastatic breast cancer in post-menopausal women.

"We appreciate the opportunity that Breakthrough Therapy designation provides to work closely with the FDA on the development of palbociclib," said Mace Rothenberg, senior vice president of clinical development and medical affairs for Pfizer's oncology unit. The company indicated that it will continue to work with the agency to determine the implications of the designation and identify the data needed to support a regulatory submission. Pfizer noted that the FDA's requirements for a submission for the drug have yet to be defined.

Interim data from the Phase II trial were presented last year at the CTRC-AACR San Antonio Breast Cancer Symposium. Pfizer noted that enrolment in the late-stage trial, named Study 1008, is open and ongoing.

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