Investigational Treatment Combo Produces Responses in HER2-Positive Metastatic Breast Cancer

Pyrotinib, a second-generation, irreversible anti-human epidermal growth factor receptor 2 (HER2) tyrosine kinase inhibitor, plus nab-paclitaxel showed promising anti-tumor activity in patients with HER2-positive advanced or metastatic breast cancer. The results were presented at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting.

The multicenter, single-arm, open-label, phase 2 study was conducted in China and included women aged 18 to 75 years with histologically or cytologically confirmed HER2-positive advanced or metastatic breast cancer. Patients had an Eastern Cooperative Oncology Group (ECOG) performance status score of 0-1, and those with primary resistance to trastuzumab and bone-only metastases were excluded from the study.

A total of 51 patients were enrolled between December 2019 and December 2021. Median patient age was 55 years (range, 35-72 years), and 23 patients (45.1%) had an ECOG score of 0. Of the total number of patients, 10 (19.6%) with metastatic disease had previously received first-line treatment, and 28 (54.9%) had received prior treatment with trastuzumab. More than half of the patients (n=29; 56.9%) had hormone receptor-positive disease. Visceral metastases occurred in 56.9% of the patients (n=29), and 26 patients (51%) were menopausal.

Patients received pyrotinib 400 mg orally daily plus nab-paclitaxel 125 mg/m² intravenously on days 1, 8, and 15 of each 28-day cycle until disease progression, unacceptable toxicity, withdrawal, or death.

As of January 21, 2022 (data cutoff), 38 patients were evaluable. The confirmed objective response rate (primary endpoint) was 81.6% (95% CI, 65.1-91.7). Responses to treatment included: complete response in 4 patients (10.5%), partial response in 27 patients (71.1%), stable disease in 6 patients (15.8%), and progressive disease in 1 patient (2.6%). Progression-free survival data were still immature at the time of reporting.

Among the full cohort, the most common grade ≥3 treatment-emergent adverse events were neutropenia (n=14; 27.5%), diarrhea (n=10; 19.6%), fatigue (n=5; 9.8%), and peripheral neuropathy (n=4; 7.8%).

Reference

Li H, Li Z, Yan M, et al. Pyrotinib plus nab-paclitaxel in patients with HER2-positive advanced or metastatic breast cancer: A multicenter, single-arm, open-label phase 2 trial. Abstract #1035. Presented at the 2022 American Society of Clinical Oncology Annual Meeting; June 3-7, 2022; Chicago, IL.