Effect of CYP2B6*6 on response in each treatment arm. Within each treatment arm, *6 and *1/*1 patients were compared for response using the Wald χ² test. Response was defined in 3 ways: CR; CR or nPR; and CR, nPR, or partial response (PR). FC-treated CYP2B6*6 patients were less likely to achieve a CR (P = .004; OR, 0.27) or CR/nPR (P = .017; OR, 0.35). In contrast, response to Chl or F alone was not influenced by CYP2B6 status.