Multidrug Resistance Proteins Do Not Predict Benefit of Adjuvant Chemotherapy in Patients with Completely Resected Non–Small Cell Lung Cancer: International Adjuvant Lung Cancer Trial Biologic Program

Purpose: The purpose of our study was to determine whether multidrug resistance proteins (MRP) are of prognostic and/or predictive value in patients who were enrolled into the International Adjuvant Lung Cancer Trial (IALT). Experimental Design: Expression of MRP1 and MRP2 was immunohistochemically assessed in tumor specimens obtained from 782 IALT patients. Prognostic and predictive analyses were based on Cox models adjusted for clinical and pathologic variables. Results: MRP1 expression was considered positive in 364 (47%) patients and MRP2 expression in 313 (40%) patients. MRP2-positive patients had a significantly shorter overall survival than MRP2-negative patients in the total patient population [adjusted hazard ratio for death, 1.37; 95% confidence interval (95% CI), 1.09-1.72; P = 0.007]. There was no significant association between MRP1 expression and overall survival. Neither MRP1 nor MRP2 predicted response to adjuvant cisplatin-based chemotherapy. Conclusions: MRP2 expression is an independent prognostic factor in patients with completely resected non–small cell lung cancer but neither MRP1 nor MRP2 was of predictive value in patients enrolled into the IALT.