Expression of organic anion-transporting polypeptide 1A2 and organic cation transporter 6 as a predictor of pathologic response to neoadjuvant chemotherapy in triple negative breast cancer

Breast Cancer Res Treat. 2014 May;145(1):101-11. doi: 10.1007/s10549-014-2913-y. Epub 2014 Mar 27.

Abstract

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.

MeSH terms

  • Adult
  • Aged
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use
  • Biomarkers, Tumor / analysis*
  • Drug Resistance, Neoplasm
  • Female
  • Humans
  • Immunohistochemistry
  • Middle Aged
  • Neoadjuvant Therapy*
  • Organic Anion Transporters / biosynthesis*
  • Organic Cation Transport Proteins / biosynthesis*
  • Retrospective Studies
  • Triple Negative Breast Neoplasms / drug therapy
  • Triple Negative Breast Neoplasms / metabolism*
  • Triple Negative Breast Neoplasms / pathology

Substances

  • Biomarkers, Tumor
  • Organic Anion Transporters
  • Organic Cation Transport Proteins
  • SLC22A16 protein, human
  • SLCO1A2 protein, human