Influence of MDR-reversing activity and quinine dose decrease on survival. (A) Analysis of the prognostic value of the MDR-reversing activity measured at day 2 of quinine infusion in 163 patients. Overall survival was not significantly improved in the 101 patients with an MDR-reversing activity higher than 1.75 compared with 62 patients with an MDR-reversing activity lower than 1.75 (P = .32). Other tested cutoff values were 1.20, 1.50, and 2.00 (not shown). (B) Influence of quinine dose decrease on overall survival in 114 patients who received ICC1. Quinine dose was decreased during either ICC1 or ICC2 in 76 patients (P = .27).