Relationship Between an Interleukin 6 SNP and Relapse After Allogeneic Bone Marrow Transplantation

Background/Objectives: Unrelated bone marrow transplantation (BMT) is a curative treatment for hematological malignancies. While HLA mismatch is a recognized risk factor in unrelated BMT, the significance of non-HLA single nucleotide polymorphisms (SNPs) remains uncertain. Cytokines play key roles in several aspects of unrelated BMT. Although the relationship between cytokine gene SNPs and BMT outcomes has been examined, the findings obtained have been inconsistent; therefore, further investigations in additional cohorts are warranted. Methods: Four SNPs in the IL2, IL6, IFN-gamma, and TGF-beta1 genes were retrospectively genotyped in 822 malignant patients and their corresponding donors who received unrelated BMT through the Japan Marrow Donor Program with compatibility at minimum HLA-A, -B, and -DRB1. The relationships between these SNP genotypes and BMT outcomes were statistically analyzed. Results: The donor interleukin-6 (IL6) SNP, rs1800796, also known as -572G>C and -634C/G, was associated with the relapse of the original disease in both univariable and multivariable regression analyses (minimum p-value = 0.0013), and the cumulative incidence curve analysis identified CC as a risk genotype (p-value = 0.0012). None of these SNPs correlated with overall survival. Conclusions: The donor IL6 SNP, rs1800796, may serve as a useful predictor of tumor relapses if validated.