An Open-Label, Single-Center, Exploratory Phase Ib/II Clinical Study of Entinostat Combined With Pyrotinib Plus Endocrine Therapy in Patients With Advanced Triple-Positive Breast Cancer After Trastuzumab Failure
This is an open-label, single-center, exploratory, Phase Ib/II clinical trial evaluating the safety and efficacy of entinostat combined with pyrotinib and endocrine therapy in patients with advanced hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-positive (HER2+) breast cancer who have failed prior trastuzumab-based therapy. The study consists of two parts: Part I (Phase Ib) employs a 3+3 dose-escalation design to determine the dose-limiting toxicity (DLT), maximum tolerated dose (MTD), and recommended Phase II dose (RP2D) of entinostat when given in combination with pyrotinib (400 mg daily) and endocrine therapy. Part II (Phase II) uses a Simon two-stage design to further evaluate the efficacy and safety of the combination at the RP2D. The primary efficacy endpoint is progression-free survival (PFS) based on RECIST v1.1. A total of approximately 79-94 participants will be enrolled.
• Age ≥ 18 and ≤ 75 years, female, premenopausal or postmenopausal.
• Histologically confirmed HR+/HER2+ breast cancer (HER2 positive defined as IHC 3+ or FISH confirmed by the pathology department of the study center).
• Histologically confirmed locally advanced breast cancer (not amenable to curative local therapy) or recurrent/metastatic breast cancer.
• Prior treatment with trastuzumab and taxane-based anticancer therapy.
• Received 1-2 prior lines of systemic anticancer therapy in the advanced setting.
• Life expectancy ≥ 3 months.
• At least one measurable lesion per RECIST v1.1.
• ECOG performance status 0-2.
• All acute toxicities from prior anticancer therapy resolved to Grade 0-1 (per NCI CTCAE v5.0), except alopecia and toxicities deemed by the investigator to pose no safety risk.
⁃ Adequate bone marrow function: ANC ≥ 1.5×10\^9/L, platelet ≥ 100×10\^9/L, hemoglobin ≥ 90 g/L.
⁃ Adequate hepatic and renal function: TBIL ≤ 1.5×ULN; ALT and AST ≤ 2.5×ULN (or ≤ 5×ULN in the presence of liver metastases); BUN and Cr ≤ 1.5×ULN with creatinine clearance ≥ 50 mL/min.
⁃ Voluntarily participate and sign written informed consent. -