Functional Genetic Variants Affecting Tacrolimus Trough Levels and Side Effects in Chinese Renal Transplantation.
Conditions: Transplantation
Sponsor: Southern Medical University, China

Title: Functional Genetic Variants Affecting Tacrolimus Trough 
Levels and Side Effects in Chinese Renal Transplantation. 
ClinicalTrials.gov ID: NCT03083769  
Date: Sep. 23, 2019 
Study Protocol and Statistical Analysis Plan 
Study Protocol: 
Aim: Renal transplant is the treatment of choice for patients with end-stage renal disease. 
Immunological rejection is the leading cause of renal allograft dysfunction after transplant, 
and immunosuppressant play the main role in preventing against it. Tacrolimus (TAC) has become 
the main immunosuppressant as it can effectively improve allograft survival and prevent acute 
rejection. The therapeutic range for TAC is narrow, underexposure to TAC may lead to acute 
rejection in transplant recipients, whereas overexposure to TAC puts patients at risk of 
TAC-related side effects including nephrotoxicity, neurotoxicity. Clinical factors and genetic 
factors play the main role in the variation in TAC trough blood concentrations. There is a necessity 
for searching genetic marker affecting TAC metabolism and side effects to guide individualized 
administration of TAC.  
Methods: Two cohorts will be enrolled in our study. The Chinese renal transplant recipients 
recruited at Nanfang Hospital will be set as the Discovery cohort. The Chinese renal recipients 
recruited at Guilin No. 924 Hospital will be set as Replication cohort. In order to identify the 
genetic variants accounted for the unexplained variability of TAC and the variants associated with 
the side effects in Chinese kidney transplant recipients, we will conduct a systematic 
candidate-SNP approach to investigate the effect of genetic polymorphisms on TAC trough blood 
concentration and side effects in two Chinese kidney transplant cohorts. The SNPs from two 
GWAS cohorts, eQTLs from GTEx database, SNPs locating at the promoters of CYP3A4, CYP3A5 
and CYP3A7 gene, and genetic variants previously reported to be associated with variation in TAC 
trough blood concentration will be analyzed in this study. Additionally, the molecular mechanisms 
of the novel functional genetic variants will be evaluated, and the impact of clinical factors on 
TAC trough blood concentrations will be also analyzed. 
 
Statistical Analysis Plan: 
Statistical analyses will be performed using software R3.4.1 (R foundation for statistical 
computing, http://www.r-project.org) and GraphPad Prism5 (https://www.graphpad.com/). The 
dose-adjusted tacrolimus C0/D without normal distribution will be log-transformed to attain 
normality. Multivariate linear regression model will be used to evaluate the association between 
TAC log(C0/D) and clinical factors. In Discovery cohort, association analysis between candidate 
SNPs and TAC log(C0/D) as well as the risk of acute rejection will be performed in five genetic 
models using software R 3.4.1 with SNPassoc package. An acute rejection free survival rates 

among different genotypes will be calculated using the Kaplan-Meier method. In Replication 
cohort, SNPassoc package was used to evaluate the association between functional SNPs and TAC 
log(C0/D), as well as the association between functional SNPs and the risk of acute rejection. A 
two-sided p value<0.05 was considered statistically significant.