Maintenance Therapy in HER2-Positive Unresectable Locally Recurrent or Metastatic Breast Cancer: A Phase II Study

Fudan University

Status and phase: Not yet enrolling; Phase 2

Conditions: HER2-positive Breast Cancer

Treatments: Drug: Trastuzumab rezetecan; Drug: Dalpiciclib; Drug: Trastuzumab; Drug: Pyrotinib; Drug: ET: Letrozole/ Anastrozole/ Exemestane/ Fulvestrant/ Leuprorelin/ Goserelin.

Study type: Interventional

Funder types: Other; Industry

Identifiers

NCT07179939

MA-BC-II-111

Details and patient eligibility

About

This is a phase II trial exploring the maintenance therapy with trastuzumab combined with pyrotinib or dalpiciclib and endocrine therapy in HER2-positive advanced breast cancer based on different hormone receptor (HR) statuses following trastuzumab rezetecan (T-DXh, SHR-A1811) as induction treatment for HER2-positive unresectable locally recurrent or metastatic breast cancer (MBC) patients.

Enrollment: 288 estimated patients

Sex: Female

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

To be eligible to participate in this trial, an individual must meet ALL the following criteria:

1. Patient must be capable to understand the purpose of the study and have signed written informed consent form (ICF) prior to beginning specific protocol procedures.

2. Female patients ≥ 18 years of age at the time of signing ICF.

3. Breast Cancer Requirements:

   1. Histologically or cytologically confirmed HER2-positive(IHC 3+ or ISH+) unresectable locally advanced or metastatic breast cancer (Note: Patients eligible for curative-intent treatment are excluded).
   2. Documented hormone receptor (HR) status.
   3. No prior systemic anti-tumor therapy for recurrent/metastatic disease (≤1 line of endocrine therapy is permitted*).
   4. For patients who received (neo)adjuvant therapy: >12 months between the end of systemic treatment (excluding endocrine therapy) and recurrence/metastasis.

4. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.

5. Adequate Organ Function.

6. Pregnancy and Contraception: Women of childbearing potential (WOCBP) must agree to use highly effective contraception from screening until7 months after the last dose of study treatment and must refrain from breastfeeding.

Exclusion criteria

An individual who meets ANY of the following criteria will be excluded from participation in this trial:

1. Known active CNS metastases not treated with surgery or radiotherapy, except for those who have achieved stable disease for ≥1 month after treatment and have discontinued corticosteroids for >2 weeks.

2. Received major cancer-related surgery, radiotherapy, chemotherapy, immunotherapy, molecular targeted therapy, biologic therapy, or investigational drug therapy within 4 weeks prior to the first dose of study treatment.

3. Previous treatment with antibody-drug conjugates containing exatecan derivative topoisomerase I inhibitors.

4. Presence of clinically significant cardiovascular conditions, including:

   1. Severe/unstable angina
   2. Symptomatic congestive heart failure (NYHA class ≥II)
   3. Clinically significant supraventricular or ventricular arrhythmias requiring treatment or intervention
   4. Myocardial infarction within 6 months before the first dose

5. Has a history of non-infectious interstitial lung disease (ILD)/pneumonitis that required steroids, has current ILD/pneumonitis, or has suspected ILD/pneumonitis that cannot be ruled out by imaging at screening.

6. Known substance abuse or any other concurrent severe and/or uncontrolled medical condition that would, in the investigator's judgment, contraindicate patient participation.

Trial design

Primary purpose: Treatment

Allocation: N/A

Interventional model: Single Group Assignment

Masking: None (Open label)

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288 participants in 1 patient group

Experimental

Experimental group

Description:

All patients will receive a 6-cycle induction phase with T-DXh 4.8 mg/kg body weight administered as an intravenous (IV) infusion on day 1 (D1) of each 21-day cycle (Q3W). Participants may continue with maintenance treatment if T-DXh is discontinued prematurely due to unacceptable toxicity prior to disease progression. During the maintenance phase, participants with HR positive disease will receive trastuzumab combined with dalpiciclib and endocrine therapy and for those with HR negative disease will receive trastuzumab combined with pyrotinib.

Treatment:

Drug: ET: Letrozole/ Anastrozole/ Exemestane/ Fulvestrant/ Leuprorelin/ Goserelin.

Drug: Pyrotinib

Drug: Trastuzumab

Drug: Dalpiciclib

Drug: Trastuzumab rezetecan