Neoadjuvant endocrine therapy with sequential palbociclib and chemotherapy based on Ki67 status in stage II-III breast cancer: An open-label, phase II study.

ABSTRACT:

Background

While neoadjuvant endocrine therapy (NET), with or without a CDK4/6 inhibitor, is an established treatment option for estrogen receptor-positive breast cancers, optimal patient selection and second-line treatment for non-responders remain uncertain.

Methods

In the open-label, phase 2 PETREMAC trial (NCT02624973), pre- and postmenopausal patients with large T2 (>4 cm) or locally advanced ER/PGR>50 %, HER2-, and TP53 wild-type breast cancers received NET (tamoxifen + goserelin for premenopausal and letrozole for postmenopausal patients). Palbociclib was added if the Ki67 reduction was ≤50 % after 14 days. Neoadjuvant chemotherapy (NAC) was introduced if NET ± palbociclib failed to reduce Ki67 sufficiently or if there was no objective response on MRI after 24 weeks.

SUBMITTER: Engebrethsen C 

PROVIDER: S-EPMC12813210 | biostudies-literature | 2026 Feb

REPOSITORIES: biostudies-literature