This is a single arm, open label, phase 2 trial aimed to investigate the biological effects and safety of neoadjuvant dalpiciclib in combination with letrozole for HR+/HER2- breast cancer. A total of 35 patients with stage IIB-III HR+/HER2- breast cancer will be enrolled. Six 4-week cycles of adjuvant therapy will be administrated. In each cycle, patients use dalpiciclib orally, 150mg, day 1-21, and letrozole orally, 2.5 mg, day 1-28. Premenopausal or perimenopausal patients should combine ovarian function suppression, including bilateral oophorectomy or treatment with gonadotropin-releasing hormone agonists. The primary endpoint is complete cell-cycle arrest at C1D15, defined as ki67≤2.7%. The secondary endpoints include residual cancer burden, overall response rate, change in Ki67 from baseline to 2 weeks of treatment, preoperative endocrine prognostic index, pathologic complete response, breast-conserving surgery rate and safety profile.
In this single arm, open label, phase 2 trial, operable patients with stage IIB-III HR+/HER2- breast cancer will be enrolled and receive six cycles of adjuvant dalpiciclib plus letrozole. This study aims to assessed the biological effects and safety of dalpiciclib in combination with letrozole for HR+/HER2- breast cancer in the neoadjuvant setting.