Korean study is first to show palbociclib benefit in premenopausal women

CHICAGO—A second trial of a CDK4/6 inhibitor in premenopausal women with HR+/HER2- metastatic breast cancer demonstrated a significant benefit in progression-free survival compared to women treated with capecitabine.

The study by Korean investigators enrolled 184 women, median age 44, all of whom were receiving tamoxifen before enrollment. The women were randomized to palbociclib following endocrine therapy with exemestane and leuprolide.

Yeon Hee Park, MD, of the Samsung Medical Center, Seoul, said that median PFS in the palbociclib arm was 20.1 months versus 14.4 months in the control group. Park reported the findings from the Young PEARL study in an oral abstract session devoted to metastatic breast cancer. The session, here at the American Society of Clinical Oncology Meeting, included a presentation of overall survival from the MONALEESA-7 trial.

Those back-t0-back results for CDK4/6 inhibitors led study discussant Angelo Di Leo, MD, PhD, to declare that CDK4/6 inhibitors should be considered “the new standard of practice” for the first-line treatment of premenopausal women with advanced HR+/HER2- breast cancer.

But the Young PEARL study findings raised some questions for Di Leo and for audience members, especially the issue of the comparator arm: why was trastuzumab not used? Park explained that the choice of a comparator boiled down to what is available in Korea. Also questioned was the lack of hormonal therapy in the capecitabine arm.

Also, there were no differences between the overall objective response rate and response duration.

Park maintained that the findings are especially useful since palbociclib is currently not approved for premenopausal women, and that “this is the first study to show palbociclib benefit in that cohort.”


Young PEARL was funded by Pfizer.

Park reported no financial disclosure.

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