The IFNG (IFN-γ) Genotype Predicts Cytogenetic and Molecular Response to Imatinib Therapy in Chronic Myeloid Leukemia

Purpose: The present study analyzed treatment outcomes of imatinib therapy by interindividual genetic variants in candidate biological pathways of chronic myeloid leukemia (CML) such as apoptosis, angiogenesis, IFN-gamma signaling pathways, or drug transport/metabolism of imatinib. Experimental Design: Peripheral blood DNAs were genotyped for 79 single nucleotide polymorphism markers involved in the pathways of apoptosis, angiogenesis, myeloid cell growth, xenobiotic metabolism, WT1 signaling, IFN signaling, and others in CML patients who were included in discovery (n = 229, Canada) and validation cohorts (n = 187, Korea). Results: We found several genotypes associated with complete cytogenetic response: IFNG (rs1861494, rs2069705), FASL (rs763110), FAS (rs2234767, rs2234978), VEGFR2 (rs1531289), and WT1 (rs2234590); with major molecular response: IFNG (rs1861494, rs2069705), BIRC5 (rs9904341), FAS (rs2234978), and ABCG2 (rs2231142); with loss of response: IFNG (rs2069705), IFNGR2 (rs9808753), BIRC5 (rs9904341), and ORM (rs3182041); and with treatment failure: IFNG (rs2069705), JAK3 (rs3212713), and ORM (rs3182041). External validation for the above significant genotypes confirmed that the IFNG genotype (rs2069705) was predictive of complete cytogenetic response (hazard ratio, 2.17; P < 0.001) and major molecular response (hazard ratio, 1.96; P = 0.0001) in validation cohorts of Korean ethnicity. Conclusions: The IFNG genotype was predictive for response to imatinib therapy, suggesting potential involvement of the IFN-gamma signaling pathway in the mechanism of action of imatinib in CML. Clin Cancer Res; 16(21); 5339-50. (C) 2010 AACR.