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 Background: For human epidermal growth factor receptor 2 (HER2) positive advanced or metastatic breast cancer, the standard therapeutic strategy is HER2-targeted agents combined with a taxane. This multicenter, single-arm phase 2 trial was designed to assess the efficacy and safety of pyrotinib (a brand-new generation, irreversible anti-HER2 tyrosine kinase inhibitor) plus nab-paclitaxel in patients with HER2-positive advanced or metastatic breast cancer. Methods: This was a multicenter, single-arm, open-label phase 2 trial conducted at seven centers in China (ChiCTR1900023653). Women aged 18-75 years, with histologically or cytologically confirmed HER-2 positive (immunohistochemistry [IHC] 3+ or positive confirmed by fluorescence in situ hybridization) advanced or metastatic breast cancer and with Eastern Cooperative Oncology Group performance score (ECOG PS) of 0-1 were enrolled. Patients with primary resistance to trastuzumab and bone-only metastases were excluded. Eligible patients received pyrotinib (400 mg, po, qd) plus nab-paclitaxel (125 mg/m2, iv, day 1/8/15) for each 28-day cycle until disease progression, unacceptable toxicity, consent withdrawal or death. The primary endpoint was objective response rate (ORR), defined as the proportion of patients with complete response (CR) or partial response (PR) according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Secondary endpoints included progression-free survival (PFS), overall survival, safety and quality of life. Results: Between December 2019 and December 2021, 51 patients were enrolled. The median age was 55 years (range 35–72). Twenty-three patients (45.1%) had ECOG PS of 0. Ten patients (19.6%) with metastatic disease had previously received first-line treatment and 28 (54.9%) had received prior treatment with trastuzumab. More than half (29 of 51, 56.9%) had hormone receptor-positive disease. Visceral metastases occurred in 56.9% of the patients (29 of 51) and 26 patients (51.0%) were menopausal. The data cutoff for the present analysis was January 21, 2022. Among 38 evaluable patients, four patients (10.5%) had CR, 27 (71.1%) had PR, six (15.8%) had stable disease, and one (2.6%) had progressive disease. The confirmed ORR was 81.6% (95% CI 65.1-91.7%). The PFS data were still immature. The most common grade ≥3 treatment-emergent adverse events included neutropenia (14 of 51, 27.5%), diarrhea (10 of 51, 19.6%), fatigue (5 of 51, 9.8%) and peripheral neuropathy (4 of 51, 7.8%). Conclusions: Pyrotinib combined with nab-paclitaxel showed a promising antitumor activity with good tolerance in patients with HER2-positive advanced or metastatic breast cancer. Clinical trial information: ChiCTR1900023653.