FDA Expands Palbociclib Approval for Breast Cancer

The Food and Drug Administration (FDA) has granted an expanded indication for the cyclin-dependent kinase 4/6 inhibitor palbociclib (Ibrance). The drug is now approved for use in combination with fulvestrant in women with hormone receptor (HR)-positive, HER2-negative advanced or metastatic breast cancer whose disease progressed following endocrine therapy.

Palbociclib was initially approved in February 2015 for the treatment of estrogen receptor–positive, HER2-negative metastatic breast cancer, in women who had not yet received endocrine therapy. The new approval was granted under the FDA’s breakthrough therapy designation.

The additional indication for palbociclib is based on results from the PALOMA-3 trial, which was stopped early in April 2015 after an interim analysis showed benefit in combination with fulvestrant when compared to fulvestrant and placebo.

The trial enrolled 521 women; results were presented at last year’s American Society of Clinical Oncology Annual Meeting in Chicago, though Pfizer reports slightly updated results in a press release.

Women who received palbociclib plus fulvestrant had a median progression-free survival of 9.5 months, compared with 4.6 months in the fulvestrant plus placebo group, for a hazard ratio of 0.461 (95% CI, 0.360–0.591; P < .0001). The overall response rate was 24.6% with palbociclib, compared with 10.9% in the placebo group. The duration of response was also longer with the study drug, at 9.3 months compared with 7.6 months in the fulvestrant plus placebo patients.

The most common adverse events of any grade were neutropenia, at 83% vs only 4% in the placebo group, leucopenia (53% vs 5%), infections (47% vs 31%), and fatigue (41% vs 29%).

“There currently is no cure for metastatic breast cancer, so ongoing treatment is usually needed to control the spread of the disease,” said Marisa Weiss, MD, the founder and chief medical officer of Breastcancer.org, in the press release. “That's why the availability of a first-of-its-kind treatment option like [palbociclib] for women dealing with HR-positive, HER2-negative metastatic disease represents a very important advance.”