TGF-a LEVELS AND RESPONSE TO LAPATINIB

Breast Cancer Res Treat. 2010 Oct 9. [Epub ahead of print]
High serum TGF-α predicts poor response to lapatinib and capecitabine in HER2-positive breast cancer.
Rhee J, Han SW, Cha Y, Ham HS, Kim HP, Oh DY, Im SA, Park JW, Ro J, Lee KS, Park IH, Im YH, Bang YJ, Kim TY.

Department of Internal Medicine, Seoul National University Hospital, 101 Daehang-Ro, Jongno-Gu, Seoul, Korea.
Abstract

Lapatinib and capecitabine combination therapy is effective in trastuzumab-resistant human epidermal growth factor receptor 2 (HER2)-positive breast cancer. We investigated the biomarkers from serum of patients receiving lapatinib and capecitabine Patients received lapatinib 1,250 mg once daily and capecitabine 2,000 mg/m(2)/day, day 1-14, every 3 weeks. Serum samples were obtained before treatment initiation. Levels of transforming growth factor-α (TGF-α), epidermal growth factor (EGF), extracellular domains of EGFR and HER2 were measured by enzyme-linked immunosorbent assay. The effect of TGF-α on in vitro sensitivity of SK-BR-3 cells to lapatinib was investigated. Sixty-four patients were included. Response rate was significantly higher in patients with low serum TGF-α (≤3.75 pg/ml) compared to high TGF-α (>3.75 pg/ml) [61.1% (11/18) vs. 17.4% (8/46), respectively; P = 0.001]. Low serum TGF-α was independently associated with better response in multivariate analysis [adjusted odds ratio, 8.96; 95% confidence interval (CI) 2.4-34.2]. Time-to-progression tended to be shorter in patients with high serum TGF-α compared to low TGF-α [median 3.8 months (95% CI 2.3-5.4) vs. 6.5 (95% CI 6.1-6.8), respectively; P = 0.067]. We confirmed that TGF-α diminished the sensitivity of SK-BR3-cells to lapatinib in vitro. The in vitro antiproliferative effect of cetuximab in combination with lapatinib was higher than that of lapatinib alone in SK-BR3-cells exposed to TGF-α. These data suggest that TGF-α plays a role in resistance to lapatinib and capecitabine therapy among HER2-positive breast cancer.