Background: The pharmacokinetic impact of multidrug resistance-1 (MDR1) gene single nucleotide polymorphisms (SNPs) has been already investigated in solid organ transplantation field, however, data is still lacking in an allogeneic stem cell transplantation (SCT) setting.
Methods: A total of 82 patients receiving an allogeneic HLA-identical sibling (n=70) or unrelated SCT (n=12) with graft-versus-host disease (GVHD) prophylaxis of cyclosporine-A (CSA) plus methotrexate (MTX) were included in the current study. Two SNPs of MDR1 gene (C3435T and G2677T/A) were analyzed using PCR/RFLP assay.
Results: As regards G2677T/A SNP, GG genotype showed a higher incidence of NRM compared to non-GG genotype (67% vs. 32%, p=0.0073), yet not C3435T (p=0.2026) or MDR1 haplotype (p=0.2238). Accordingly, overall survival (OS) was significantly correlated with G2677T/A genotype (p=0.0048), yet not with C3435T (p=0.5041) or MDR1 haplotype (p=0.4086). However, no difference in the relapse incidence was noted according to G2677T/A, C3435T genotype or MDR1 haplotype. In a multivariate analysis, those patients without GG genotype at G2677T/A were found to have favorable prognosis in terms of OS (p=0.003) or NRM (p=0.031) along with occurrence of chronic GVHD (p<0.001 for OS, p=0.001 for NRM), standard disease risk (p=0.045 for OS) or acute grade 0,1 GVHD (p=0.019 for NRM). However, no correlation was found between the blood concentrations of CSA and MDR1 genotype and CSA neurotoxicity and MDR1 genotype.
Conclusion: The G2677T/A genotype seemed to be associated with the transplantation outcomes, especially NRM. Further study is warranted to clarify its mechanism of MDR1 SNPs other than pharmacokinetic aspects.