The pharmacogenetics of mycophenolate mofetil in Tunisian renal transplant patients

Post-transplant complications revealed by mycophenolate mofetil related transporters and metabolic enzymes gene polymorphisms in pediatric patients with hematological disorders

BACKGROUND

Haploidentical hematopoietic stem cell transplantation (Haplo-HSCT) serves as an important option for patients without an HLA matched donor in treating hematological disorders, while patients may experience various complications after transplantation. Mycophenolate mofetil (MMF), a cornerstone drug for graft-versus-host disease (GvHD) prophylaxis, effectively reduces the incidence of acute GvHD, and the efficacy of MMF varies among individuals associated with MMF-related transporters and metabolic enzymes single nucleotide polymorphisms (SNPs). However, limited studies have systematically reported the correlations between the MMF-related SNPs and post-transplant complications.

METHODS

Here, we conducted a retrospective study involving 90 pediatric patients with hematological disorders who underwent haplo-HSCT at a single center. All patients were subjected to MMF-related SNP testing, combined with common clinical characteristics, to be correlated with post-transplant complications.

RESULTS

We observed that all 15 MMF-related SNPs were in Hardy-Weinberg equilibrium. Based on multivariate Cox regression analysis of post-transplant complications, we discovered that SLCO1B1 (521T > C) variant genotype was an independent protective factor for chronic GvHD (HR = 0.25, 95% confidence interval (CI) (0.08-0.84)). For viral infection, CYP2C8 (1291 + 106T > C) variant genotype was an independent risk factor for cytomegalovirus infection (HR = 2.98, 95% CI (1.18-7.53)). As to hemorrhagic cystitis, SLCO1B1 (1865 + 4846T > C) variant genotype was an independent protective factor, while older age was considered as an independent risk factor (HR = 0.41, 95% CI (0.19-0.85); HR = 2.52, 95% CI (1.14-5.54), respectively). No statistical significance was discovered between common clinical characteristics and MMF-related SNPs with other complications, including grade II-IV/III-IV acute GvHD, Epstein-Barr virus infection, peri-engraftment syndrome, and capillary leak syndrome. We also discovered SLCO1B1 (597 C > T) and SLC29A1 (-162 + 228 A > C) variant genotypes are both independent factors for cumulative incidence of relapse after haplo-HSCT (HR = 4.02, 95% CI (1.42-11.44); HR = 0.18, 95% CI (0.07-0.43), respectively).

CONCLUSIONS

Our findings highlight the significance of MMF-related transporters and metabolic enzymes SNPs in the development of post-transplant complications, contributing to facilitating personalized risk assessment and improving the clinical management in haplo-HSCT patients.

Influence of genetic polymorphisms on pharmacokinetics and treatment response of mycophenolic acid: a scoping review

This scoping review explores the impact of genetic polymorphisms on the pharmacokinetics and treatment responses of mycophenolic acid (MPA), an immunosuppressant. The study includes 83 articles from 1226 original studies, focusing on transplantation (n = 80) and autoimmune disorders (n = 3). Genetic variants in uridine 5'-diphospho-glucuronosyltransferase (UGT1A9, UGT1A8 and UGT2B7) and transmembrane transporters (ABCC2, SLCO1B1, SLCO1B3 and ABCB1) significantly affected MPA's pharmacokinetics and susceptibility to its adverse effect. Whereas variants in several genes including UGT1A9, UGT2B7, IMPDH1 and IMPDH2 have been associated with a higher risk of transplant rejection. However, there is a lack of studies on MPA's impact on autoimmune disorders and limited research on the Asian population. The findings underscore the need for further research on MPA's impact across different populations and diseases, particularly among other Asian ethnic groups, to advance personalized medicine in MPA therapy.

The pharmacogenetics of tacrolimus in renal transplant patients: association with tremors, new-onset diabetes and other clinical events

Our study is the first study to investigate the effect of SNPs in CYP3A5, CYP3A4, ABCB1 and POR genes on the incidence of tremors, nephrotoxicity, and diabetes mellitus. A total of 223 renal transplant patients receiving tacrolimus and mycophenolate mofetil (MMF) were recruited. Both adults and children patients participated in the study. Genotyping was performed using PROFLEX-PCR followed by RFLP. MPA and tacrolimus plasma concentrations were measured by immunoassay. The AUC0-12h of MMF was estimated by a Bayesian method. We found a statistically significant association between the CYP3A5*3 and CYP3A4*1B genotypes and the tacrolimus exposure. We found a lower occurrence of nephrotoxicity (p = 0.03), tremor (p = 0.01), and new-onset diabetes (p = 0.002) associated with CYP3A5*1 allele. The CYP3A4*1B allele was significantly associated with a lower occurrence of new-onset diabetes (p = 0.026). The CYP3A5*1 allele was significantly associated with an increased risk of acute and chronic rejection (p = 0.03 and p < 0.001, respectively). Our results support the usefulness of tacrolimus pharmacokinetics in pre-kidney transplant assessments.