Pyrotinib Combined With Trastuzumab and Pertuzumab for Maintenance Therapy in HER2-Positive Advanced Breast Cancer

Prior treatment

• Other malignancy diagnosed within 5 years prior to enrollment.

Lab values

• Prior treatment with any tyrosine kinase inhibitor targeting HER2 and/or epidermal growth factor receptor (EGFR) including pyrotinib, lapatinib, tucatinib, neratinib, and afatinib.

Other

• Patients who are difficult or unable to be followed-up.
• Other reasons that, in the investigator's judgment, make the patient unsuitable for participation in this study.

• Age ≥ 18 years, male or female.
• Histologically or cytologically confirmed HER2-positive advanced breast cancer (IHC 3+, or IHC 2+ with ISH amplification), with known HR status.
• Have unresectable locally advanced or metastatic disease. If recurrent (after \[neo\]adjuvant therapy), must be at least 6 month treatment free from any trastuzumab and pertuzumab received in the early breast cancer setting for advanced HER2+ disease.
• Have received 4-8 cycles of pre-study induction therapy including only trastuzumab, pertuzumab, and taxane as first-line of therapy for the treatment of advanced breast cancer prior to study enrollment. Participants are eligible provided they are without evidence of disease progression following completion of induction therapy.
• CNS Inclusion - Based on screening contrast-enhanced brain magnetic resonance imaging (MRI), participants may have any of the following: No evidence of brain metastases. Untreated brain metastases which are asymptomatic not needing immediate local treatment and, if identified on prior brain imaging, without evidence of progression since starting first-line induction therapy with trastuzumab, pertuzumab, and taxane
• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0-2
• Have planned to receive maintenance anti-tumor therapy with pyrotinib in combination with HP
• Negative serum pregnancy test; women of childbearing potential must use a highly effective contraceptive method from study initiation until at least 6 months after the last dose of study medication.
• Voluntary participation with written informed consent obtained prior to any study-related procedures.