High expression of organic anion transporter 2 and organic cation transporter 2 is an independent predictor of good outcomes in patients with metastatic colorectal cancer treated with FOLFOX-based chemotherapy

摘要

Although metastatic colorectal cancer (mCRC) is commonly treated with 5-fluorouracil (5-FU)/leucovorin/oxaliplatin (FOLFOX), their response to FOLFOX varies, and no biomarkers predictive of treatment outcome have been validated. Organic anion transporter 2 (OAT2) and organic cation transporter 2 (OCT2) are critical determinants in uptake of 5-FU and oxaliplatin, respectively. In this study, we evaluated whether OAT2 and OCT2 levels can predict effectiveness of FOLFOX-based therapy. We retrospectively assessed 90 patients with mCRC who were treated with first-line FOLFOX with or without bevacizumab. We immunohistochemically determined OAT2 and OCT2 expression levels at invasion fronts of their tumors and correlated the levels to clinicopathological parameters, including objective tumor response (OTR) and progression-free survival (PFS). High expression of OAT2 (OAT2^High) and OCT2 (OCT2^High) were detected in 36% and 60% of the tumors, respectively. OCT2^High was significantly associated with invasion depth (P=0.03), whereas OAT2^High was not associated with any clinicopathological parameters. In univariate analysis, OAT2^High was significantly correlated with good OTR (P=0.02), and OCT2^High with long PFS (P=0.03). Multivariate analyses showed that OAT2^High and OCT2^High, respectively, were the sole independent predictors of good OTR (P=0.02) and long PFS (P=0.03). We found that patients with OAT2^High/OCT2^High showed the best treatment outcomes (good OTR and long PFS) with significantly higher frequency than patients with other expression patterns (P=0.003). OAT2^High/OCT2^High status was also the only independent predictive factor in multivariate analysis. This study suggests that OAT2^High and OCT2^High are important independent predictors of good outcomes in FOLFOX-treated mCRC.