Multicenter phase II study of apatinib single or combination therapy in HER2-negative breast cancer involving chest wall metastasis

OBJECTIVE: Breast cancer (BC) with chest wall metastasis (CWM) usually shows rich neovascularization. This trial explored the clinical effect of apatinib on human epidermal growth factor receptor 2 (HER2)-negative advanced BC involving CWM. METHODS: This trial involved four centers in China and was conducted from September 2016 to March 2020. Patients received apatinib 500 mg/d [either alone or with endocrine therapy if hormone receptor-positive (HR+)] until disease progression or unacceptable toxicity. Progression-free survival (PFS) was the primary endpoint. RESULTS: We evaluated 26 patients for efficacy. The median PFS (mPFS) and median overall survival (mOS) were 4.9 [range: 2.0−28.5; 95% confidence interval (95% CI): 2.1−8.3] months and 18 (range: 3−55; 95% CI: 12.9−23.1) months, respectively. The objective response rate (ORR) was 42.3% (11/26), and the disease-control rate was 76.9% (20/26). In the subgroup analysis, HR+ patients compared with HR-negative patients had significantly improved mPFS of 7.0 (95% CI: 2.2−11.8) monthsvs. 2.3 (95% CI: 1.2−3.4) months, respectively (P=0.001); and mPFS in patients without or with chest wall radiotherapy was 6.4 (95% CI: 1.6−19.5) monthsvs. 3.0 (95% CI: 1.3−4.6) months, respectively (P=0.041). In the multivariate analysis, HR+ status was the only independent predictive factor for favorable PFS (P=0.014). CONCLUSIONS: Apatinib was highly effective for BC patients with CWM, especially when combined with endocrine therapy. PFS improved significantly in patients with HR+ status who did not receive chest wall radiotherapy. However, adverse events were serious and should be carefully monitored from the beginning of apatinib treatment.