Pharmacogenomic variations in treatment protocols for childhood acute lymphoblastic leukemia

Objectives. This retrospective study evaluates the role of pharmacogenomic determinants in the treatment of childhood acute lymphoblastic leukemia (ALL) in the Taiwanese population. Methods. A total of 105 childhood ALL patients received combined chemotherapy of different intensities based on risk-directed Taiwan Pediatric Oncology Group (TPOG)-ALL-93 protocols. Seventeen genetic polymorphisms in 13 pharmacogenomic targets were analyzed by PCR-based restriction fragment length polymorphism (RFLP) and sequence-specific oligonucleotide (SSO) probe hybridization. Pharmacogenomic polymorphisms were correlated with event-free survival (EFS) of patients, with confounding effects adjusted by multivariate regression. Results. Three polymorphic alleles in the multi-drug resistance 1 (MDR1) ABCB1 gene, and homozygotic MDR1 2677GG, 3435CC, and 2677G-3435C genotypes were highly associated with a significant reduction in EFS in those patients treated by the standard risk (SR) protocol (TPOG-ALL-93-SR). The hazard ratios were 6.8 (p=0.01), 21.7 (p=0.009), and 6.8 (p=0.01), respectively. Conclusions. Independent pharmacogenomic determinants associated with treatment outcome were identified in subsets of Taiwanese ALL patients. ? 2009 Wiley-Liss, Inc.