Primary Tumor Levels of Tissue Inhibitor of Metalloproteinases-1 Are Predictive of Resistance to Chemotherapy in Patients with Metastatic Breast Cancer

Abstract

Only about 50% of metastatic breast cancer patients benefit from cytotoxic chemotherapy. Today, no validated markers exist for prediction of chemotherapy sensitivity/resistance in this patient group. Tissue inhibitor of metalloproteinases-1 (TIMP-1) has been shown to protect against apoptosis, and the purpose of the present study was to test the hypothesis that tumors expressing high levels of TIMP-1 are protected against apoptosis-inducing agents and thus less sensitive to apoptosis-inducing chemotherapeutic drugs. We investigated the association between primary tumor expression levels of TIMP-1 protein and objective response to first-line chemotherapy in 173 patients with metastatic breast cancer. When analyzed as a continuous log-transformed variable, increasing TIMP-1 levels were significantly associated with lack of response to cyclophosphamide/methotrexate/5-fluorouracil and anthracycline-based chemotherapy (P = 0.01; odds ratio, 2.0; 95% confidence interval, 1.1-3.3). In a multivariate model, including lymph node status, steroid hormone receptor status, menopausal status, dominant metastases site, type of chemotherapy, and disease-free interval, TIMP-1 was significantly associated with resistance to treatment (P = 0.03; odds ratio, 1.7; 95% confidence interval, 1.1-3.3). In the present exploratory study, we showed that elevated tumor tissue TIMP-1 levels were significantly associated with a poor response to chemotherapy. By using TIMP-1, we identified a group of patients with metastatic breast cancer, which hardly respond to the most frequently used chemotherapy regimes (i.e., cyclophosphamide/methotrexate/5-fluorouracil and anthracyclines).