Adequate tacrolimus exposure modulates the impact of HLA class II molecular mismatch: a validation study in an American cohort.

Clinicians have few tools to predict the risk of alloimmune injury that would guide immunosuppression management in renal transplant patients. We evaluated human leukocyte antigen (HLA)-DR/DQ molecular mismatch to predict de novo donor-specific antibodies (DSAs) during the first year of transplant and explored how differences in tacrolimus exposure may modulate this risk. HLA-DR and -DQ eplet mismatches were determined between 444 donor-recipient pairs in Denver, Colorado between 2007 and 2013. Previously defined mismatch thresholds stratified recipients into low- (N = 119), intermediate- (N = 153), and high- (N = 172) risk categories. The area under the curve for DSA at 1 year was 0.84 and 0.82 for HLA-DR and HLA-DQ eplet mismatches, respectively. Compared to low-risk patients, there was a graded increase in risk of DR/DQ DSA in intermediate (HR 15.39, 95% CI 2.01-118.09, p = .009) and high-risk (HR 23.81, 95% CI 3.17-178.66, p = 0.002) categories. Intermediate- and high-risk patients with a mean tacrolimus <6 ng/ml versus >8 ng/ml had increased risk of DR/DQ DSA at 1 year (HR 2.34, 95% CI 1.05-5.22, p = .04). HLA molecular mismatch represents a reproducible, objective, and clinically relevant tool to stratify patients by alloimmune risk and may help guide personalized immunosuppression management.

SARS Cov-2 infection in a renal-transplanted patient: A case report.

The clinical manifestation of COVID-19 can vary from an asymptomatic course to ARDS requiring invasive mechanical ventilation and extracorporeal membrane oxygenation. A kidney transplanted patient infected with SARS CoV-2 infection showed a mild disease despite immune suppression. It is possible that Immunosuppression can "be protective" as the cytokine storm is an important factor in the disease story. Despite the good outcome reported in the present case report, is remains of vital importance the solid organ transplant patients use precautions in order to avoid the infection.

A comprehensive review of the impact of tacrolimus intrapatient variability on clinical outcomes in kidney transplantation.

Tacrolimus (Tac) is widely used to prevent rejection and graft loss in solid organ transplantation. A limiting characteristic of Tac is the high intra and interpatient variability associated with its use. Routine therapeutic drug monitoring (TDM) is necessary to facilitate Tac management and to avoid undesirable clinical outcomes. However, whole blood trough concentrations commonly utilized in TDM are not strong predictors of the detrimental clinical outcomes of interest. Recently, researchers have focused on Tac intrapatient variability (Tac IPV) as a novel marker to better assess patient risk. Higher Tac IPV has been associated with a number of mechanisms leading to shortened graft survival. Medication nonadherence (MNA) is considered to be the primary determinant of high Tac IPV and perhaps the most modifiable risk factor. An understanding of the methodology behind Tac IPV is imperative to its recognition as an important prognostic measure and integration into clinical practice. Therapeutic interventions targeting MNA and reducing Tac IPV are crucial to improving long-term graft survival.

Clinical course of COVID-19 in a liver transplant recipient on hemodialysis and response to tocilizumab therapy: A case report.

The novel coronavirus disease 2019 (COVID-19) is a highly infectious and rapidly spreading disease. There are limited published data on the epidemiology and outcomes of COVID-19 infection among organ transplant recipients. After initial flulike symptoms, progression to an inflammatory phase may occur, characterized by cytokine release rapidly leading to respiratory and multiorgan failure. We report the clinical course and management of a liver transplant recipient on hemodialysis, who presented with COVID-19 pneumonia, and despite completing a 5-day course of hydroxychloroquine, later developed marked inflammatory manifestations with rapid improvement after administration of off-label, single-dose tocilizumab. We also highlight the role of lung ultrasonography in early diagnosis of the inflammatory phase of COVID-19. Future investigation of the effects of immunomodulators among transplant recipients with COVID-19 infection will be important.

Distinct peripheral blood molecular signature emerges with successful tacrolimus withdrawal in kidney transplant recipients.

Tacrolimus (Tac) is an effective anti-rejection agent in kidney transplantation, but its off-target effects make withdrawal desirable. Although studies indicate that Tac can be safely withdrawn in a subset of kidney transplant recipients, immune mechanisms that underlie successful vs unsuccessful Tac removal are unknown. We performed microarray analyses of peripheral blood mononuclear cells (PBMC) RNA from subjects enrolled in the Clinical Trials in Organ Transplantation-09 study in which we randomized stable kidney transplant recipients to Tac withdrawal or maintenance of standard immunosuppression beginning 6 months after transplant. Eight of 14 subjects attempted but failed withdrawal, while six developed stable graft function for ≥2 years on mycophenolate mofetil plus prednisone. Whereas failed withdrawal upregulated immune activation genes, successful Tac withdrawal was associated with a downregulatory and proapoptotic gene program enriched within T cells. Functional analyses suggested stronger donor-reactive immunity in subjects who failed withdrawal without evidence of regulatory T cell dysfunction. Together, our data from a small, but unique, patient cohort support the conclusion that successful Tac withdrawal is not simply due to absence of donor-reactive immunity but rather is associated with an active immunological process.

A case of SARS-CoV-2 pneumonia with successful antiviral therapy in a 77-year-old man with a heart transplant.

The SARS-CoV-2 infection can be seen as a single disease, but it also affects patients with relevant comorbidities who may have an increased risk of a severe course of infection. In this report, we present a 77-year-old patient with a heart transplant receiving relevant immunosuppressive therapy who tested positive for SARS-CoV-2 after several days of dyspnea, dry cough, and light general symptoms. Computed tomography confirmed interstitial pneumonia. The patient received antiviral therapy with hydroxychloroquine and showed no further deterioration of the clinical state. After 12 days of hospitalization, the patient was released; he was SARS-CoV-2 negative and completely asymptomatic.

Butyric acid normalizes hyperglycemia caused by the tacrolimus-induced gut microbiota.

Approximately 33.6% of nondiabetic solid organ transplant recipients who received tacrolimus developed hyperglycemia. Whether the tacrolimus-induced gut microbiota is involved in the regulation of hyperglycemia has not been reported. Hyperglycemia was observed in a tacrolimus-treated mouse model, with reduction in taxonomic abundance of butyrate-producing bacteria and decreased butyric acid concentration in the cecum. This tacrolimus-induced glucose metabolic disorder was caused by the gut microbiota, as confirmed by a broad-spectrum antibiotic model. Furthermore, oral supplementation with butyrate, whether for remedy or prevention, significantly increased the butyric acid content in the cecum and arrested hyperglycemia through the regulation of glucose-regulating hormones, including glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and insulin, in serum. The butyrate-G-protein-coupled receptor 43-GLP-1 pathway in the intestinal crypts may be involved in the pathogenesis of normalization of hyperglycemia caused by the tacrolimus. Therefore, tacrolimus affects glucose metabolism through the butyrate-associated GLP-1 pathway in the gut, and oral supplementation with butyrate provides new insights for the prevention and treatment of tacrolimus-induced hyperglycemia in transplant recipients.

The tacrolimus-induced glucose homeostasis imbalance in terms of the liver: From bench to bedside.

Tacrolimus (TAC), the mainstay of maintenance immunosuppressive agents, plays a crucial role in new-onset diabetes after transplant (NODAT). Previous studies investigating the diabetogenic effects of TAC have focused on the ß cells of islets. In this study, we found that TAC contributed to NODAT through directly affecting hepatic metabolic homeostasis. In mice, TAC-induced hypoglycemia rather than hyperglycemia during starvation via suppressing gluconeogenetic genes, suggesting the limitation of fasting blood glucose in the diagnosis of NODAT. In addition, TAC caused hepatic insulin resistance and triglyceride accumulation through insulin receptor substrate (IRS)2/AKT and sterol regulatory element binding protein (SREBP1) signaling, respectively. Furthermore, we found a pivotal role of CREB-regulated transcription coactivator 2 (CRTC2) in TAC-induced metabolic disorders. The restoration of hepatic CRTC2 alleviated the metabolic disorders through its downstream molecules (eg, PCK1, IRS2, and SREBP1). Consistent with the findings from bench, low CRTC2 expression in graft hepatocytes was an independent risk factor for NODAT (odds ratio = 2.692, P = .023, n = 135). Integrating grafts' CRTC2 score into the clinical model could significantly increase the predictive capacity (areas under the receiver operating characteristic curve: 0.71 vs 0.79, P = .048). Taken together, in addition to its impact on pancreatic cells, TAC induces "hematogenous diabetes" via CRTC2 signaling. Liver-targeted management may be of help to prevent or heal TAC-associated diabetes.

Tacrolimus troughs and genetic determinants of metabolism in kidney transplant recipients: A comparison of four ancestry groups.

Tacrolimus trough and dose requirements vary dramatically between individuals of European and African American ancestry. These differences are less well described in other populations. We conducted an observational, prospective, multicenter study from which 2595 kidney transplant recipients of European, African, Native American, and Asian ancestry were studied for tacrolimus trough, doses, and genetic determinants of metabolism. We studied the well-known variants and conducted a CYP3A4/5 gene-wide analysis to identify new variants. Daily doses, and dose-normalized troughs were significantly different between the four groups (P < .001). CYP3A5*3 (rs776746) was associated with higher dose-normalized tacrolimus troughs in all groups but occurred at different allele frequencies and had differing effect sizes. The CYP3A5*6 (rs10264272) and *7 (rs413003343) variants were only present in African Americans. CYP3A4*22 (rs35599367) was not found in any of the Asian ancestry samples. We identified seven suggestive variants in the CYP3A4/5 genes associated with dose-normalized troughs in Native Americans (P = 1.1 × 10-5 -8.8 × 10-6 ) and one suggestive variant in Asian Americans (P = 5.6 × 10-6 ). Tacrolimus daily doses and dose-normalized troughs vary significantly among different ancestry groups. We identified potential new variants important in Asians and Native Americans. Studies with larger populations should be conducted to assess the importance of the identified suggestive variants.

Late intra-patient tacrolimus trough level variability as a major problem in kidney transplantation: A Collaborative Transplant Study Report.

Intra-patient variability (IPV) of tacrolimus trough level has been associated with poor outcome after kidney transplantation. These findings were derived from single-center analyses and restricted mainly to measurements early after transplantation. We analyzed in a multicenter effort whether high IPV of tacrolimus levels at posttransplant years 1, 2, and 3 was associated with impaired clinical outcome. More than 6600 patients who received a deceased donor kidney transplant during 2000-2014 and had a functioning graft for >3 years were studied. Graft survival was significantly impaired with increasing IPV (P < 0.001). As compared to patients with a low IPV of <30%, the risk of graft loss during years 4-6 increased 32% in patients with an IPV of 30% to 44% and 66% in patients with an IPV of ≥45% (P = 0.002 and P < 0.001). About one-third of patients showed an IPV of ≥30% with substantially impaired outcome. Even in patients with good outcome during the first 3 posttransplant years, a high IPV was associated with inferior graft survival. Our data indicate that a fluctuating tacrolimus trough level at years 1, 2, and 3 posttransplant is a major problem in kidney transplantation.

Evidence of a clinically significant drug-drug interaction between cannabidiol and tacrolimus.

Cannabidiol (CBD), a major purified nonpsychoactive component of cannabis with anticonvulsant properties, was approved by the U.S. Food and Drug Administration (FDA) in June 2018 as an adjuvant treatment for refractory epilepsy (Epidiolex; GW Pharmaceuticals). CBD is metabolized by cytochrome P450 (CYP)3A4 and CYP2C19 with a growing body of evidence suggesting it is also a potent inhibitor of these pathways. We report for the first time a significant drug-drug interaction between the purified CBD product and tacrolimus. A participant in a CBD clinical trial for epilepsy who was also receiving tacrolimus showed an approximately 3-fold increase in dose-normalized tacrolimus concentrations while receiving 2000-2900 mg/day of CBD. Our report delineates an important concern for the transplant community with the increasing legalization of cannabis and advent of an FDA-approved CBD product. Larger studies are needed to better understand the impact of this drug-drug interaction in solid organ transplant recipients.

Comparison of the effects of standard vs low-dose prolonged-release tacrolimus with or without ACEi/ARB on the histology and function of renal allografts.

Targeting the renin-angiotensin system and optimizing tacrolimus exposure are both postulated to improve outcomes in renal transplant recipients (RTRs) by preventing interstitial fibrosis/tubular atrophy (IF/TA). In this multicenter, prospective, open-label controlled trial, adult de novo RTRs were randomized in a 2 × 2 design to low- vs standard-dose (LOW vs STD) prolonged-release tacrolimus and to angiotensin-converting enzyme inhibitors/angiotensin II receptor 1 blockers (ACEi/ARBs) vs other antihypertensive therapy (OAHT). There were 2 coprimary endpoints: the prevalence of IF/TA at month 6 and at month 24. IF/TA prevalence was similar for LOW vs STD tacrolimus at month 6 (36.8% vs 39.5%; P = .80) and ACEi/ARBs vs OAHT at month 24 (54.8% vs 58.2%; P = .33). IF/TA progression decreased significantly with LOW vs STD tacrolimus at month 24 (mean [SD] change, +0.42 [1.477] vs +1.10 [1.577]; P = .0039). Across the 4 treatment groups, LOW + ACEi/ARB patients exhibited the lowest mean IF/TA change and, compared with LOW + OAHT patients, experienced significantly delayed time to first T cell-mediated rejection. Renal function was stable from month 1 to month 24 in all treatment groups. No unexpected safety findings were detected. Coupled with LOW tacrolimus dosing, ACEi/ARBs appear to reduce IF/TA progression and delay rejection relative to reduced tacrolimus exposure without renin-angiotensin system blockade. ClinicalTrials.gov identifier: NCT00933231.

Abatacept as rescue immunosuppression after calcineurin inhibitor treatment failure in renal transplantation.

A majority of kidney transplant recipients receive calcineurin inhibitor-based immunosuppression. However, some do not tolerate calcineurin inhibitors and require other immunosuppressive strategies. Until recently, alternative approaches have been associated with inferior outcomes, but recent methods have effectively utilized belatacept in calcineurin inhibitor-intolerant patients. Though promising, belatacept uptake has been limited by higher acute rejection rates, unavailability due to production shortages, and logistical challenges as a result of intravenous infusion requirements. Interestingly, its predecessor abatacept is clinically available in subcutaneous formulation to treat autoimmune disorders but has not been used in clinical transplantation. Here we report on a series of 9 calcineurin inhibitor-intolerant transplant recipients converted to abatacept early after transplant as rescue immunosuppression during periods of belatacept unavailability. Retrospective review revealed successful allograft salvage and 100% patient and graft survival (median 115 months) after conversion to abatacept. Patients received abatacept for a median duration of 82 months with stable, long-term renal allograft function, a single cellular rejection episode, and no clinically apparent protective immunity concerns. Hence our findings suggest that future clinical studies utilizing abatacept either de novo or as conversion therapy in transplant recipients should be considered.

Lower tacrolimus exposure and time in therapeutic range increase the risk of de novo donor-specific antibodies in the first year of kidney transplantation.

De novo donor-specific antibodies (dnDSAs) have been associated with reduced graft survival. Tacrolimus (TAC)-based regimens are the most common among immunosuppressive approaches used in in clinical practice today, yet an optimal therapeutic dose to prevent dnDSAs has not been established. We evaluated mean TAC C0 (tacrolimus trough concentration) and TAC time in therapeutic range for the risk of dnDSAs in a cohort of 538 patients in the first year after kidney transplantation. A mean TAC C0  < 8 ng/mL was associated with dnDSAs by 6 months (odds ratio [OR] 2.51, 95% confidence interval [CI] 1.32-4.79, P = .005) and by 12 months (OR 2.32, 95% CI 1.30-4.15, P = .004), and there was a graded increase in risk with lower mean TAC C0 . TAC time in the therapeutic range of <60% was associated with dnDSAs (OR 2.05, 95% CI 1.28-3.30, P = .003) and acute rejection (hazard ratio [HR] 4.18, 95% CI 2.31-7.58, P < .001) by 12 months and death-censored graft loss by 5 years (HR 3.12, 95% CI 1.53-6.37, P = .002). TAC minimization may come at a cost of higher rates of dnDSAs, and TAC time in therapeutic range may be a valuable strategy to stratify patients at increased risk of adverse outcomes.

Immunosuppressive effect of the gut microbiome altered by high-dose tacrolimus in mice.

The alterations induced in gut microbiota by tacrolimus may affect immune function and organ transplantation. Mice were treated with high-dose tacrolimus for 14 days. The fecal microbiota were analyzed by pyrosequencing the 16S rRNA genes, and the effect on metabolism was predicted using the sequence data. The subgroups of T cells in the serum, gut-associated lymphoid tissue, and draining lymph nodes were determined by flow cytometry. Tacrolimus treatment significantly altered the relative abundance of Allobaculum, Bacteroides, and Lactobacillus and CD4+ CD25hi FoxP3+ regulatory T cells in the colonic mucosa and the circulation. These were significantly increased after either tacrolimus treatment or treatment by fecal microbiota transfer from tacrolimus-treated donors. Further, treatment with low-dose tacrolimus plus fecal microbiota transfer from high-dose tacrolimus-altered mice increased skin allograft survival rate in a skin transplantation model. Thus, high-dose tacrolimus alters the compositions and taxa of the gut microbiota. Administration of these conditioned gut microbiota plus low-dose tacrolimus resulted in regulation of colonic and systemic immune responses and an increased allograft survival rate. This study demonstrated a new strategy for controlling allograft rejection by combining an immunosuppressive agent with gut microbiome transplantation.

A donor and recipient candidate gene association study of allograft loss in renal transplant recipients receiving a tacrolimus-based regimen.

This work investigated, in two large cohorts of French renal transplants treated with tacrolimus, the influence of donor and recipient ABCB1, CYP3A4, and CYP3A5 genotypes on the risk of allograft loss. A discovery and a replication population of 330 and 369 adult renal transplant patients, each from a different transplantation center and all receiving a tacrolimus-based immunosuppressive regimen, were retrospectively genotyped. The influence of genetic factors and other known risk factors on allograft loss was investigated using multivariate Cox proportional hazard analyses. The existence of previous transplantations (per unit HR = 1.89 [1.10-3.26] P = .0216) and the donor ABCB1 c.1199GA/AA genotype (GA/AAvs GG: HR = 3.22 [1.14-9.09], P = .0288) were associated with an increased risk of allograft loss in the discovery cohort and with graft loss due to humoral rejection in the replication cohort (per unit HR = 2.26 [1.34-3.81], P = .00229; GA/AAvs GG HR = 3.42 [1.28-9.16], P = .0142). Genotyping the donor for the ABCB1 c.1199 G>A (exon 11, rs2229109) allele may be of interest before prescribing tacrolimus to the recipient, although this polymorphism is rather rare and its effect may be limited to certain mechanisms of graft loss.

High tacrolimus trough level variability is associated with rejections after heart transplant.

Tacrolimus, the major immunosuppressant after heart transplant (HTx) therapy, is a narrow therapeutic index drug. Hence, achieving stable therapeutic steady state plasma concentrations is essential to ensure efficacy while avoiding toxicity. Whether high variability in steady state concentrations is associated with poor outcomes is unknown. We investigated the association between tacrolimus trough level variability during the first year post-HTx and outcomes during and beyond the first postoperative year. Overall, 72 patients were analyzed for mortality, of whom 65 and 61 were available for rejection analysis during and beyond the first year post-HTx, respectively. Patients were divided into high (median >28.8%) and low tacrolimus level variability (<28.8%) groups. Mean tacrolimus levels did not differ between the groups (12.7 ± 3.4 ng/mL vs 12.8 ± 2.4 ng/mL, P = .930). Patients in the high variability group exhibited higher long-term rejection rate (median total rejection score: 0.33 vs 0, P = .04) with no difference in rejection scores within the first year post-HTx. Multivariate analysis showed that high tacrolimus trough level variability was associated with >8-fold increased risk for any rejection beyond the first year post-HTx (P = .011). Mortality was associated only with cardiovascular complications (P = .018), with no effect of tacrolimus through level variability.

Prospective randomized study of conversion from tacrolimus to cyclosporine A to improve glucose metabolism in patients with posttransplant diabetes mellitus after renal transplantation.

Tacrolimus (TAC) increases the risk of posttransplant diabetes (PTDM) compared with cyclosporine A (CYC). The present 12-month, multicenter, investigator-driven, prospective, randomized study was designed to assess whether conversion from tacrolimus to CYC can reverse PTDM after renal transplantation. Predominantly white patients with PTDM according to the 2005 American Diabetes Association criteria were randomized to either replacement of TAC with CYC or continuation of their TAC-based regimen after stratification for type of glucose-lowering therapy, steroid therapy, and hepatitis C status. At 12 months, 14 of 41 patients with complete data in the CYC arm (34%; 95%CI 19%-49%) were free of diabetes, whereas this was the case in only 4 of 39 patients (10%; 95%CI 3%-20%) in the TAC arm (P = .01). At 12 months, 39% of patients in the CYC arm were off glucose-lowering medication vs 13% of patients in the TAC arm (P = .01). The CYC group decreased glycated hemoglobin level during the 12-month follow-up, resulting in significantly lower levels compared with the TAC group (6.0 ± 0.9% vs 7.1 ± 1.7% at 12 months; P = .002). In conclusion, replacement of TAC with CYC significantly improves glucose metabolism and has the potential to reverse diabetes during the first year after conversion. (EU Clinical Trials Register No. 2006-001765-42).

Increasing tacrolimus time-in-therapeutic range is associated with superior one-year outcomes in lung transplant recipients.

Calcineurin inhibitors (CNIs) are the backbone of traditional immunosuppressive regimens for lung transplant recipients (LTR). The CNIs are both narrow therapeutic index drugs with significant interpatient and intrapatient variability that require therapeutic drug monitoring to ensure safety and effectiveness. We hypothesized that tacrolimus time-in-therapeutic range (TTR) affects acute and chronic rejection rates in LTRs. This was a single-center, observational, cross-sectional study of 292 adult LTRs. Subjects who received tacrolimus posttransplant for the first year were included. TTR was calculated at 1 year using protocol goal ranges (12-15 mg/mL months 0-6; 10-12 mg/mL for months 7-12). The primary outcome was acute cellular rejection (ACR) burden at 1 year. Chronic lung allograft dysfunction (CLAD), mortality, and infection rate were assessed as secondary outcomes at 1 year. Primary and secondary outcomes were assessed using logistic regression. Increasing TTR by 10% was associated with a significantly lower likelihood of high-burden ACR at 1 year on univariable (OR 0.46, 95% CI 0.40-0.54, P < .001) and multivariable (OR 0.64, 95% CI 0.47-0.86, P = .003) assessment, controlling for age and induction agent. Increasing TTR by 10% was also associated with lower rates of CLAD (P < .001) and mortality (P < .001) at 1 year. Prospective studies confirming these findings appear warranted.