Richard Finn, MD, Division of Hematology/Oncology at the Jonsson Comprehensive Cancer Center, University of California, Los Angeles, describes results from a phase II study that examined PD 0332991, an oral selective inhibitor of cyclin-dependent kinase 4/6, in combination with letrozole as a treatment for postmenopausal women with metastatic ER-positive breast cancer.

In the trial, 165 patients were randomized 1:1 to receive letrozole alone or in combination with PD 0332991. Patients were further stratified into two parts based on molecular characteristics. Part 2 of the study contained patients with CCND1 amplification and/or a loss of p16 expression.

Finn explains that the addition of PD 0332991 to letrozole resulted in a dramatic improvement between all subgroups of the trial. The median progression-free survival (PFS) benefit for the combination was 26.1 months compared to 7.5 months for letrozole alone (HR = 0.37; 

A phase III trial is planned to begin in 2013 to further examine the efficacy of PD 0332991 in breast cancer.

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Richard Finn, MD, from the Jonsson Comprehensive Cancer Center, describes results from a phase II study that examined PD 0332991 in combination with letrozole for women with metastatic ER-positive breast cancer.

Richard S. Finn, MD

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Dr. Finn on PD 0332991 Plus Letrozole in Breast Cancer