Breast Cancer Coverage from Every Angle

SABCS 2020: Initial PENELOPE-B Results With Palbociclib-Based Therapy for Primary Breast Cancer

By: Vanessa A. Carter, BS
Posted: Friday, December 11, 2020

Despite adjuvant hormone therapy, relapse occurs in about one-third of patients with HER2-negative, hormone receptor–positive, primary breast cancer with residual invasive disease after chemotherapy. At the 2020 San Antonio Breast Cancer Symposium (SABCS; Abstract GS1-02), Sibylle Loibl, MD, PhD, of German Breast Group, Neu-Isenburg, Germany, and colleagues presented initial findings from the phase III PENELOPE-B, which found that 1 year of palbociclib treatment did not seem to improve invasive disease–free survival in these patients at high risk for relapse after neoadjuvant chemotherapy.

This study enrolled a total of 1,250 women who did not have a pathologic complete response following taxane-containing chemotherapy, had ypN-positive, and had a high risk of relapse. After completing chemotherapy and locoregional therapy, patients were randomly assigned 1:1 to receive either a placebo with standard endocrine therapy for 21 days or 13 cycles of palbociclib (125 mg) daily.

The majority (89%) of participants completed at least seven therapy cycles. The proportions of patients who received an aromatase inhibitor, tamoxifen, tamoxifen plus gonadotropin-releasing hormone, and aromatase inhibitor plus gonadotropin-releasing hormone were 50.1%, 49.8%, 9.7%, and 6.6%, respectively. Infections and vascular disorders were the most common serious adverse events, with eight fatalities reported.

The investigators reported 152 invasive disease–free survival events in those receiving endocrine therapy plus palbociclib, at a median follow-up of 42.8 months, compared with 156 such events in those who received endocrine therapy alone. In addition, regardless of age, risk status, and Ki67 index, the findings were consistent across subgroups. Finally, no overall survival benefit was shown with palbociclib.

Disclosure: For full disclosures of study authors, visit

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