Significance of lung resistance-related protein in clinical outcome of acute leukemic patients with reference to p-glycoprotein

Lung resistance-related protein (LRP) over-expression in leukemic blast cells from acute leukemia patients, and the effect of LRP or P-glycoprotein (P-gp) on the clinical outcome of acute leukemia were investigated individually by dividing patients into four groups. The complete remission (CR) rate of group I (LRP and P-gp both negative) was 81.7%, group II (only LRP-positive) 87.5%, group III (only P-gp-positive) 87.1%, and group IV (LRP and P-gp both positive) 40.0%. There were no statistical differences between group I and group II or group III, but a significant difference was observed between group I, II, or III and group IV. Median overall survival in group IV was significantly shorter (4.6 months) than in group I, II, or III, although no significant differences were observed between group I and groups II or III (18.9, 20.5, 31.8 months). There was a tendency for disease-free survival in group III to be longer than that in group I, II or IV. The reasons for these findings are discussed. Our present results indicate that the coexistence of LRP and P-gp strongly influenced effectiveness of induction chemotherapy, and long term prognosis, whereas isolated presence of LRP or P-gp did not.