Pyrotinib in patients with HER2-positive advanced breast cancer: A multicenter, retrospective, real-world study

Abstract Purpose: Pyrotinib, a novel human epidermal growth factor receptor 2 (HER2)-targeted tyrosine kinase inhibitor (TKI), was approved for second-line standards of treatment for HER2-positive advanced breast cancer (ABC) in China. This real-world study aimed to assess the actual efficacy and safety of pyrotinib in HER2+ ABC.Methods: In this multicenter, retrospective, observational real-world study, we analyzed 171 patients with HER2+ ABC, who received pyrotinib-based treatment from November 2017 to November 2020. The primary end point was progression-free survival (PFS). Results: Up to November 30, 2021, the median PFS (mPFS) was 12.0 months (95% CI, 10.4-13.6) for all patients. When compared with Eastern Cooperative Oncology Group performance status (ECOG-PS) of 2-4, patients with the ECOG-PS of 0-1 had significant longer PFS (12.9 months vs. 6.7 months, p<0.0001). Patients receiving pyrotinib as first-line treatment demonstrated a significantly longer PFS than those who received pyrotinib as second-line or beyond treatment (13.0 months vs. 10.7 months, p=0.020). Furthermore, lapatinib-naive patients exhibited a significant longer mPFS compared to lapatinib-treated patients (12.2 months vs. 8.1 months, p=0.021). One hundred and sixty-two patients (94.7%) with measurable lesions had been included in efficacy assessment, and objective response rate (ORR) was 45.1%. The most common adverse event (AE) was diarrhea (86.5%). Conclusion: Pyrotinib dramatically improved the clinical outcomes of HER2+ ABC with imaginable toxicities, especially for patients who received first-line treatment and had the ECOG-PS of 0-1, as well as those who were lapatinib-naive.Trial registration: ChiCTR2100051632, Sep 28, 2021