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William J. Gradishar, MD, FACP, FASCO


ASCO 2023: Palbociclib Maintenance in Second-Line Endocrine Therapy for Advanced Breast Cancer

By: Amanda E. Ruffino, BA
Posted: Thursday, June 8, 2023

Antonio Llombart-Cussac, MD, PhD, of Universidad Católica de Valencia, Barcelona, Spain, and colleagues presented the findings of the PALMIRA trial at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 1001), which explored the potential benefit of maintaining the CDK4/6 inhibitor palbociclib in second-line endocrine therapy in patients with hormone receptor–positive, HER2-negative advanced breast cancer who had received prior palbociclib therapy. They found this therapeutic strategy did not significantly improve progression-free survival compared with endocrine therapy alone in the second-line setting. Further analysis of biomarkers may help to identify which patients may be more likely to benefit from this therapeutic approach, they noted.

A total of 198 patients with hormone receptor–positive, HER2-negative advanced breast cancer who had experienced disease progression on first-line palbociclib plus endocrine therapy were included in the study. The patients were randomly assigned to receive either palbociclib plus second-line endocrine therapy or second-line endocrine therapy alone.

The results showed that at a median follow-up of 8.7 months, there was no significant difference in the median investigator-assessed progression-free survival between the two treatment groups: 4.2 months with palbociclib versus 3.6 months without it. The 6-month progression-free survival rate was 40.9% with palbociclib plus endocrine therapy and 28.6% with endocrine therapy alone. According to the investigators, there were no significant differences in overall response rate or clinical benefit rate between the two groups. Although no new safety signals were identified, the rate of grade 3 or 4 adverse events was higher with palbociclib than without (45.2% vs. 8.3%), and no treatment-related deaths were reported.

Disclosure: For full disclosures of the study authors, visit

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