Association Between Genetic Variants in Immune Response Genes and Outcomes After Hematopoietic Cell Transplantation

Despite rapid advances in allogeneic hematopoietic cell transplant (HCT) techniques, the procedure continues to be associated with a high morbidity and mortality with transplant related mortality (TRM) ranging from 15% to as high as 50%. Acute graft versus host disease (GvHD) remains a major cause of morbidity and an important cause of early TRM in patients undergoing allogeneic HCT. Though variations in major histocompatibiliy (MHC) genes are well known determinants of acute GvHD, there is increasing evidence that genetic variation in immune/cytokine response pathways also contributes significantly to the pathogenesis of acute GvHD.

We evaluated the association of single nucleotide polymorphisms (SNPs) in non-MHC dependent immune/cytokine response pathways (n= 77 SNPs in recipients and donors) with acute GvHD and TRM at one year in a cohort of 425 recipient-donor pairs who underwent allogeneic HCT for treatment of hematologic malignancies at the University of Minnesota between 1998 and 2007. We used a Fine and Gray proportional hazards model adjusted for competing risk to evaluate the association between the genetic variants and time to acute GvHD and time to TRM.

After adjustment for recipient age at transplant, race, diagnosis, disease status at transplant, gender mismatch, CMV serostatus of recipient and donor, recipient and donor sex, donor type, conditioning regimen (myeloablative or reduced intensity) and year of transplant, one recipient SNP, rs646005 in the TIRAP gene and one donor SNP, rs2232596 in the LBP gene were marginally associated with increased risk for grade II-IV acute GvHD (Hazard ratio (HR) = 1.33 (95% Confidence interval (CI): 1.07 – 1.62) and 1.32 (1.07 – 1.66) respectively; p =0.01). Similar analyses for TRM showed recipient SNP rs5498 in the ICAM1 gene was associated with a decreased risk of TRM (HR: 0.67(95% CI: 0.50 – 0.89); p=0.0006) while recipient SNPs rs1739654 in the LBP gene and rs3804100 in the TLR2 gene were associated with an increased TRM risk (HR: 1.86 (95% CI: 1.16 – 2.97) and 1.66 (95% CI: 1.11 – 2.48) respectively; p =0.01).

These findings are consistent with previous reports that support a role for genetic variants in the innate immune response pathways among both recipients and donors can influence the risk of acute GvHD and TRM among patients undergoing allogeneic HCT. These findings indicate that a systematic search for genetic variants in the innate immune response pathways may identify novel biomarkers that can be used to identify patients at high risk for acute GvHD and TRM.

Weisdorf:Genzyme: Consultancy, Research Funding.