Pyrotinib Combined With Dalpiciclib Combined With Letrozole in ER-positive and HER2-positive Advanced Breast Cancer

This is a a multicenter Phase II clinical study investigating efficacy of pyrotinib combined with dalpiciclib combined with letrozole in ER-positive and HER2-positive advanced breast cancer patients. Patients receive pyrotinib 320mg/d, dalpiciclib 125mg/d, d1-21, q28d. One cycle is 28d.

Inclusion criteria

• The subjects voluntarily joined the study, signed the informed consent, and had good compliance
• Postmenopausal or premenopausal/perimenopausal women aged ≥18 years and ≤75 years
• Patients with recurrent/metastatic breast cancer confirmed by histopathology with positive ER expression and positive HER2 expression
• Have at least one extracranial measurable lesion that meets RECIST 1.1 criteria
• At most one previous trastuzumab containing systemic therapy for recurrent metastatic breast cancer

Exclusion criteria

• Subjects had untreated central nervous system metastasis
• Bilateral breast cancer, inflammatory breast cancer, or latent breast cancer
• Previous treatment with any CDK4/6 inhibitors
• Inability to swallow, intestinal obstruction, or other factors affecting drug use and absorption
• Subject has had other malignancies (except cured basal cell carcinoma of the skin and carcinoma in situ of the cervix) within 5 years or at the same time