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  • Expression of organic anion...
    Hashimoto, Yumi; Tatsumi, Shigenobu; Takeda, Risa; Naka, Ayano; Ogane, Naoki; Kameda, Yoichi; Kawachi, Kae; Shimizu, Satoru; Sakai, Mai; Kamoshida, Shingo

    Breast cancer research and treatment, 05/2014, Volume: 145, Issue: 1
    Journal Article

    Organic anion-transporting polypeptide 1A2 (OATP1A2) and organic cation transporter 6 (OCT6) are involved in the uptake of taxanes and anthracyclines, respectively. The aim of this study was to evaluate expression levels of OATP1A2 and OCT6 as a predictor of response to neoadjuvant chemotherapy (NAC) in breast cancer. A total of 124 patients who received anthracycline/taxane-based NAC were included. Expression levels of OATP1A2 and OCT6 were immunohistochemically assessed in core needle biopsies obtained prior to NAC. A pathologic good response (pGR) and a pathologic complete response (pCR) were achieved in 24 and 10 % of patients, respectively. In univariate analysis of the entire cohort, negative hormone receptor (HR) status (pGR and pCR, P  < 0.001), high Ki-67 level (pGR, P  = 0.03; pCR, P  = 0.02), triple negative (TN) subtype (pGR, P  = 0.001; pCR, P  < 0.001), and high OCT6 (pGR, P  = 0.003) were associated with the response. In combined analysis, high OATP1A2/high OCT6 level was also a significant factor for pGR ( P  = 0.001) and pCR ( P  = 0.001). Two separate multivariate analyses showed that HR status, TN subtype and combined high OATP1A2/high OCT6 level were significant independent predictors. When TN and non-TN tumors were assessed separately in univariate analysis, high Ki-67 level ( P  = 0.04) were associated with pGR and combined high OATP1A2/high OCT6 level was associated with both pGR ( P  = 0.005) and pCR ( P  = 0.03) in the TN group. Multivariate analysis identified the combined high OATP1A2/high OCT6 level as the sole independent predictor of pGR. In the non-TN group, negative HR status ( P  = 0.03) and positive HER2 status ( P  = 0.005) were associated with pGR, but HER2 status was the sole independent predictor of pGR. These results suggest that response-associated predictors may differ between the TN and non-TN tumors. Combined high OATP1A2/high OCT6 may be a potential predictor of response to anthracycline/taxane-based chemotherapy in breast cancer, especially in TN tumors.