Calcineurin Inhibitors Tacrolimus Research Articles

Abstract Tu031: Immunosuppression Drug Modulation of Endothelial Cell Function

Heart transplantation is a life-saving therapy for patients with end-stage heart failure with over 4,000 transplants occurring per year. The use of immunosuppression drugs is necessary in post transplantation to prevent graft rejection. Proliferation signal inhibitors have previously been shown to effectively reduce the incidence of cardiac allograft vasculopathy (CAV) compared to calcineurin inhibitors but the differential mechanisms that drive this benefit and differences in vascular profile of immunosuppression drugs remain incompletely understood. In this study, we examined the direct effect of immunosuppressive agents on endothelial function to define cellular mechanisms that may contribute to differential vascular phenotypes. We used endothelial cells derived from human induced pluripotent stem cells (iPSCs) and treated them with calcineurin inhibitor (tacrolimus), mTOR inhibitor (sirolimus), or vehicle for 5 days with daily media changes. We examined endothelial function using scratch wound assay, tube formation assay, and LDL uptake. We also examined metabolic changes using Seahorse assay owing to metabolic changes induced by immunosuppression drugs in other organs. Our results indicate mTOR inhibitor (sirolimus) resulted in a reduction in endothelial cell proliferation and migration using the scratch wound assay and tube formation assay compared to vehicle or calcineurin inhibitor (tacrolimus)-treated cells. Sirolimus also reduced LDL uptake in iPSC-derived endothelial cells compared to vehicle or tacrolimus-treated cells. Tacrolimus was associated with a trend towards altered endothelial energetics. Tacrolimus and sirolimus exert differential endothelial cell functional profiles that do not fully explain the clinical outcomes observed suggesting a need to explore the drug endothelial profiles in the context of vascular injury and inflammation.

#1888 Association between intrapatient variability of serum tacrolimus levels with the development of diabetes in post-kidney transplantation patients

Abstract Background and Aims Kidney transplantation is the most cost-effective renal replacement therapy compared to dialysis. Diabetes is main cause of increased cardiovascular risk and death. Post-transplant Diabetes Mellitus (PTDM) it refers to presence of diabetes in an environment after kidney transplantation; According to the ADA (American Diabetes Association) criteria, the diagnosis must be made with a tolerance test with 75 grams of oral glucose (Oral glucose tolerance test-OGTT) or the determination of glycosylated hemoglobin 1Ac (Hb1Ac) in a post-transplant period of stability of the immunosuppression dose and without infections. There are various risk factors for the development of PTDM: hypomagnesemia, glucocorticoids, calcineurin inhibitors (tacrolimus and cyclosporine); hepatitis C virus and cytomegalovirus infections. In a Mexican kidney transplant recipients in Guadalajara, Andrade SG demonstrated that the incidence of PTDM was 10.1% at 1 year post-transplant. In the Spanish population, Porrini E demonstrated that tacrolimus represents a risk factor for the development of PTDM, increasing the incidence of prediabetes by 33% at 12 months post-transplant. Several mechanisms have been implicated in the association of calcineurin inhibitor and PTDM: decreased insulin secretion, glucose intolerance, reduced pancreatic beta cell mass, increased islet apoptosis and decreased insulin gene expression. Studies mention that tacrolimus (FK) is more diabetogenic than cyclosporine (CsA) especially at levels above 20 ng/mL. The DIRECT study (Diabetes Incidence after Renal Transplantation) showed the incidence in 73 kidney transplant patients with CsA (26%) and 96 FK patients (33.6%, p = 0.046). By the other side, Malik RF mentions that FK levels aren´t a risk factor for the development of PTDM. To demonstrate that the high intrapatient variability of tacrolimus/cyclosporine serum levels correlates with the development of diabetes (PTDM) in kidney transplant recipients at the central military hospital in Mexico City. Method Observational, analytical, longitudinal and retrospective study. All kidney transplant recipients from living donors and cadaveric donors from January 2002 to December 2020 were included. FK and CsA were used as maintenance immunosuppression. Serum levels of FK/CsA, Hb1Ac and glucose were measured at months 0, 3, 6, 9 and 12 and intra-patient variability (IPV) of FK/CsA levels was calculated for each patient. The patients were separated into 2 groups, IPV low and IPV high according to the mean the coefficient of variability (CV). The IPV of the calcineurin inhibitor was estimated by calculating the CV in each patient according to the following equation: CV(%)= (SD/mean trough concentration of FK/ CsA)×100. The diagnosis of PTDM followed the criteria of the American Diabetes Association. The Mann Whitney U test was used. Results 638 kidney transplant recipients were included. The mean age of the recipients was 36.78 (±12.81) years. At the time of kidney transplant, the BMI was 22.67 (±3.90) and 25.76 (±3.99) kg/m² BS at 1 year post-transplant for whole cohort. At 1 year post-transplant, 72.3% patients were on FK and 27.7% on CsA. Hb1Ac for whole cohort was 4.81 (±0.71)% and 4.84 (±0.77)% at month 0 and 12 post-kidney transplant, respectively. FK and CsA levels were 12.41 (±5.31) and 234.34 (±87.80) ng/mL and 9.13 (±5.3) and 194.38 (±92.44) ng/mL in the PTDM and non-PTDM groups, respectively (p = 0.029). 17.96% of patients developed PTDM. Mean CV of the entire cohort was 33.84 (±20.41)%. When performing the analysis of the IPV coefficient by subgroups of maintenance immunosuppression used at 1 year post-transplant: the IPV of FK was 43.39 (±18.49)% and 29.99 (±17.56)% in the PTDM and non-PTDM groups respectively, p = 0.000, which shows that patients with a high IPV coefficient of tacrolimus developed more PTDM than those with low variability, student's t-test to compare IPV was 0.03. The IPV of CsA was 38.61 (±18.76)% and 37.51 (±25.67)% in the PTDM and non-PTDM groups respectively, p = 0.819. Conclusion High intrapatient variability of tacrolimus was correlated with the development of PTDM in Mexican kidney transplant recipients.

#1214 Post-kidney transplant cancer: incidence, risk factors and future perspectives. Real-world analysis of a single Italian center

Abstract Background Our retrospective observational study aims to describe the epidemiology of cancer after KTx and to investigate its risk factors and the impact on therapeutic management and survival, in a big monocentric cohort of kidney transplant patients (KT-ps). The association between a specific modification of immunosuppressive therapy after cancer diagnosis and survival outcomes will be analyzed. Methods Retrospective collection of data in KTx-ps transplanted between January 2004 and December 2021, subjected to outpatient follow-up with a median follow-up of 7 [1-19] years. Results We included 930 KTx-ps with mean age at KTx of 49 years. 91% had received pre-TR dialysis, for an average of 52 months. The majority had received KTx from a deceased donor (84%). 74% had undergone induction therapy with Basiliximab and 26% ATG. Maintenance therapy included in most cases the use of steroids (87%), calcineurin inhibitors (tacrolimus 92%, ciclosporin 8%), and mycophenolate (94.6%). Patients with at least one cancer (CAN+) were 177 (19%). The mean time from TR to oncological diagnosis was 83 months. Non-melanoma skin cancers (NMSC) were the most common tumors (55%), while solid tumors were observed in 38.6% of cases. Deceased donor was more represented in CAN+. CAN+ were older and with higher BMI. They had greater presence of vasculitis as basic nephropathy. In the period between 2016 and 2021, induction therapy with ATG was significantly associated with CAN+. In multivariable analysis, ATG emerged as an independent risk factor for CAN+ (p=0.014) and, in survival analyses, ATG was strongly and significantly related to the earlier development of CAN+ (p=0.010). During follow up, cancer-related causes were the second cause of mortality (23%); the average time from cancer diagnosis to death was 23 months. The median survival from TR was 148 (CAN+) and 82 months (CAN−). After oncological diagnosis, significant evidence on tumor survival was derived from the shift to mTOR inhibitors compared to the group with definitive drug suspension (p=0.004). Conclusion The data reported by our study confirm the relevance of cancer as a complication in KTx. ATG represent an independent risk factor for cancer; in this context, a personalized choice of immunosuppressive therapy to be proposed at the time of TR represents a crucial point in the prevention of neoplastic risk. In the KTx-ps, therapeutic strategies with antineoplastic agents and management of immunosuppression therapy after malignancy remain important research perspectives in the near future.

Post-transplant cyclophosphamide, calcineurin inhibitor, and mycophenolate mofetil compared to anti-thymocyte globulin, calcineurin inhibitor, and methotrexate combinations as graft-versus-host disease prophylaxis post allogeneic stem cell transplantation from sibling and unrelated donors in patients with acute myeloid leukemia: a study on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.

Post-transplant cyclophosphamide plus calcineurin inhibitor (CNI)(tacrolimus or cyclosporine A) plus mycophenolate mofetil (PTCy/TAC or CSA/MMF) and anti-thymocyte globulin plus CNI (tacrolimus or cyclosporine A) plus methotrexate (ATG/TAC or CSA/MTX) are common graft-versus-host disease (GVHD) prophylaxis regimens. We compared the two regimens in patients with acute myeloid leukemia (AML) undergoing allogeneic transplantation from matched siblings or unrelated donors. 402 received PTCy/TAC or CSA/MMF and 5648 received ATG/TAC or CSA/MTX. Patients in the PTCy-based group were younger (48.7 vs. 51.5 years, p = 0.024) and there was a higher frequency of patient cytomegalovirus seropositivity and female donor to male patient combination in this group (77.8% vs. 71.8%, p = 0.009 and 18.4% vs. 14.4%, p = 0.029, respectively). More patients in the PTCy-based group received reduced-intensity conditioning (51.5% vs. 41%, p < 0.0001). No differences were observed in the incidence of acute GVHD grade II-IV and III-IV (21.2% vs. 20.4%, p = 0.92 and 8.1% vs. 6%, p = 0.1) or 2-year total and extensive chronic GVHD (33.7% vs. 30%, p = 0.09 and 10.7% vs. 11.2%, p = 0.81) between the groups. In the multivariate analysis, all transplant outcomes did not differ between the groups. PTCy/CNI/MMF and ATG/CNI/MTX are alternative regimens for GVHD prophylaxis in AML patients.

In Vitro Profiling of Commonly Used Post-transplant Immunosuppressants Reveals Distinct Impact on Antiviral T-cell Immunity Towards CMV.

Infectious complications, including widespread human cytomegalovirus (CMV) disease, frequently occur after hematopoietic stem cell and solid organ transplantation due to immunosuppressive treatment causing impairment of T-cell immunity. Therefore, in-depth analysis of the impact of immunosuppressants on antiviral T cells is needed. We analyzed the impact of mTOR inhibitors sirolimus (SIR/S) and everolimus (EVR/E), calcineurin inhibitor tacrolimus (TAC/T), purine synthesis inhibitor mycophenolic acid (MPA/M), glucocorticoid prednisolone (PRE/P) and common double (T+S/E/M/P) and triple (T+S/E/M+P) combinations on antiviral T-cell functionality. T-cell activation and effector molecule production upon antigenic stimulation was impaired in presence of T+P and triple combinations. SIR, EVR and MPA exclusively inhibited T-cell proliferation, TAC inhibited activation and cytokine production and PRE inhibited various aspects of T-cell functionality including cytotoxicity. This was reflected in an in vitro infection model, where elimination of CMV-infected human fibroblasts by CMV-specific T cells was reduced in presence of PRE and all triple combinations. CMV-specific memory T cells were inhibited by TAC and PRE, which was also reflected with double (T+P) and triple combinations. EBV- and SARS-CoV-2-specific T cells were similarly affected. These results highlight the need to optimize immune monitoring to identify patients who may benefit from individually tailored immunosuppression.

Age-Related Brain Atrophy and the Positive Effects of Behavioral Enrichment in Middle-Aged Beagles.

Aging dogs serve as a valuable preclinical model for Alzheimer's disease (AD) due to their natural age-related development of β-amyloid (Aβ) plaques, human-like metabolism, and large brains that are ideal for studying structural brain aging trajectories from serial neuroimaging. Here we examined the effects of chronic treatment with the calcineurin inhibitor (CNI) tacrolimus or the nuclear factor of activated T cells (NFAT)-inhibiting compound Q134R on age-related canine brain atrophy from a longitudinal study in middle-aged beagles (36 females, 7 males) undergoing behavioral enrichment. Annual MRI was analyzed using modern, automated techniques for region-of-interest-based and voxel-based volumetric assessments. We found that the frontal lobe showed accelerated atrophy with age, while the caudate nucleus remained relatively stable. Remarkably, the hippocampus increased in volume in all dogs. None of these changes were influenced by tacrolimus or Q134R treatment. Our results suggest that behavioral enrichment can prevent atrophy and increase the volume of the hippocampus but does not prevent aging-associated prefrontal cortex atrophy.

Current Perspectives on Letermovir and Maribavir for the Management of Cytomegalovirus Infection in Solid Organ Transplant Recipients.

Cytomegalovirus (CMV) infection is arguably the most important infectious complication that negatively affects the outcome of solid organ transplantation. For decades, CMV management after transplantation has relied on antiviral drugs that inhibit viral DNA polymerase (ganciclovir, foscarnet, and cidofovir). However, their use has been complicated by myelosuppression, nephrotoxicity, and selection of drug-resistant viruses. During the past few years, the therapeutic armamentarium for the management of CMV in solid organ transplant recipients has expanded with the approval of letermovir for CMV prophylaxis in high-risk CMV D+/R- kidney recipients, and maribavir for the treatment of refractory and resistant CMV infection. Both drugs offer significant improvement when compared to standard anti-CMV therapies; letermovir was as efficacious for CMV prevention, whereas maribavir was more effective in treating refractory and resistant CMV infections. Both letermovir and maribavir have favorable safety profiles compared to CMV DNA polymerase inhibitors, without the risk of neutropenia and leukopenia associated with ganciclovir and renal toxicities associated with foscarnet and cidofovir. Moreover, letermovir and maribavir are orally bioavailable, which allows convenient outpatient treatment. However, letermovir and maribavir have a significant drug interaction potential in solid organ transplant recipients, resulting in higher levels of calcineurin inhibitors (cyclosporine and tacrolimus) and mTOR inhibitors (sirolimus and everolimus). Both letermovir and maribavir are CMV-specific and do not have clinical efficacy against other herpes viruses. Thus, there is a need for additional antiviral drugs to prevent herpes simplex and other herpes viruses when clinically indicated. This article provides a comprehensive review of the clinical data supporting the use of letermovir and maribavir in clinical practice. The author provides perspectives on the role of these newly approved drugs in the current management landscape of CMV infection in solid organ transplantation.

Secreted frizzled-related protein 2 ameliorates diabetic cardiomyopathy by activating mitophagy

ObjectivesSecreted frizzled-related protein 2 (SFRP2), a novel adipokine that used to be considered an inhibitor of the canonical Wnt pathway, may play a protective role in metabolic disorders. However, its effect on diabetic cardiomyopathy was still unclear. Accumulating evidence indicates that mitophagy can protect cardiac function in the diabetic heart. The present study aimed to explore the roles of SFRP2 on diabetic cardiomyopathy, focusing on the effects and mechanisms for regulating mitophagy. MethodsWild-type H9c2 cells, Sfrp2 overexpression and knockdown H9c2 cells were exposed to a glucolipotoxic milieu. Reactive oxygen species (ROS) production, cell viability, apoptosis, mitophagy and lysosomal activity were detected. The interaction of SFRP2 with frizzled 5 (FZD5), and its effect on expression and intracellular localization of transcription factor EB (TFEB) and β-catenin were also explored. Diabetic rats and Sfrp2 overexpression diabetic rats were constructed to further document the findings from the in vitro study. ResultsThe expression of SFRP2 was low and mitophagy was inhibited in H9c2 cells in a glucolipotoxic milieu. Sfrp2 overexpression activated mitophagy and reduced H9c2 cells injury, whereas Sfrp2 deficiency inhibited mitophagy and worsened this injury. Consistent with the in vitro findings, Sfrp2 overexpression ameliorated the impairment in cardiac function of diabetic rats by activating mitophagy. Sfrp2 overexpression upregulated the expression of calcineurin and TFEB, but did not affect β-catenin in vitro and in vivo. The calcineurin inhibitor tacrolimus can inhibit mitophagy and worsen cell injury in Sfrp2 overexpression H9c2 cells. Furthermore, we found that FZD5 is required for the SFRP2-induced activation of the calcineurin/TFEB pathway and interacts with SFRP2 in H9c2 cells. Transfection with small interfering RNA targeting FZD5 opposed the effects of Sfrp2 overexpression on mitophagy and cell survival in a glucolipotoxic environment. ConclusionsSFRP2 can protect the diabetic heart by interacting with FZD5 and activating the calcineurin/TFEB pathway to upregulate mitophagy in H9c2 cells.

Blockade of Common Gamma Chain Cytokine Signaling with REGN7257, an Interleukin 2 Receptor Gamma (IL2RG) Monoclonal Antibody, in Combination with Costimulatory Blockers Delayed Skin Graft Rejection in Mice

There is a current medical need to identify innovative maintenance therapies to prevent allograft rejection in solid organ transplantation. During transplant rejection, recipient immune cells identify a grafted organ as foreign and attack it: CD4 + T cells orchestrate transplant rejection by recruiting a range of effector cells responsible for the damage of rejection including CD8 + T cells, NK cells, B cells and macrophages. These pathogenic immune cell responses can be driven by cytokines of the common gamma chain (γ c) cytokine family (IL2, IL4, IL7, IL9, IL15, and IL21). γ c cytokines signal through their corresponding receptors, expressed primarily on immune cells, that share a common coreceptor, interleukin 2 receptor subunit gamma (IL2RG) that is required for signaling. To understand the role of γ c cytokines in driving transplant rejection, we generated REGN7257, a fully human IL2RG monoclonal antibody that inhibits γ c cytokine-induced signaling, and we tested its ability to suppress allogeneic immune cell responses in a mouse model of skin graft rejection when delivered as a monotherapy and in combination with mycophenolate mofetil (MMF) or T cell costimulatory pathway blockers. In this model, recipient B6/129 (mixed background) Il2rg hu/hu mice were transplanted with tail skin from BALB/cJ donor mice. Graft survival was analyzed using a log rank Mantel-Cox test to detect statistically significant differences across groups (*=p&amp;lt;0.033; **= p&amp;lt;0.002; ***=p&amp;lt;0.0002; ****=p&amp;lt;0.0001). In a mouse model of skin graft rejection, γ c cytokine signaling blockade with REGN7257 given as maintenance immunosuppression effectively improved overall graft survival (Median Survival Time [MST] IL2RG=13) compared to mice that received a control antibody (MST CTRL=9 [****vs IL2RG Ab]), and with similar efficacy to that observed with the calcineurin inhibitor tacrolimus (MST TAC=12.5 [**vs control, n.s. vs IL2RG Ab]). In treatment combination experiments, while monotherapy treatment with the antiproliferative agent MMF was not as efficient as REGN7257 at delaying skin graft rejection (MST MMF=10 [*vs control] and MST IL2RG=12 [*vs MMF]), simultaneous blockade of cell proliferation and γ c cytokine signaling conferred an advantage over monotherapies (MST MMF+IL2RG=15.5 [****vs control, **vs IL2RG Ab]). Similarly, induction therapy consisting of γ c cytokine signaling blockade followed by maintenance immunosuppression using the CTLA4-Ig fusion protein abatacept, significantly improved overall skin graft survival (MST IL2RG+CTLA4=19.5 [****vs control]) compared to REGN7257 induction only (MST IL2RG=11 [****vs control and combo]) or abatacept maintenance only (MST CTLA4=10 [*vs control, ****vs combo]). Finally, maintenance immunosuppression combining blocking of γc cytokine signaling together with blocking of both CD28 and CD40L costimulatory signals prolonged skin graft survival better than any combination therapies of only 2 pathway blockers (MST TRIPLE=26 [**vs control] and MST DOUBLE=16-21 [n.s.-** vs triple]). Overall, our study showed that γ c cytokine blockade could potentially be an alternative to calcineurin inhibitor-based regimens to prevent rejection by specifically targeting immune cells. Our data also highlighted the inherent complexity of effector mechanisms and pathways involved in allograft rejection and showed that prolonged allograft survival requires simultaneous blockade of multiple T cell activating signals, including inhibition of cytokine signaling and costimulatory signals. These data provide evidence of γ c cytokines as key drivers of allogeneic immune cell responses during acute transplant rejection, offering a potentially novel strategy for the management of transplant patients.

Hyperglycemia and Hyperlipidemia with Kidney or Liver Transplantation: A Review.

Although solid organ transplantation in persons with diabetes mellitus is often associated with hyperglycemia, the risk of hyperlipidemia in all organ transplant recipients is often underestimated. The diagnosis of diabetes often predates transplantation; however, in a moderate percentage of allograft recipients, perioperative hyperglycemia occurs triggered by antirejection regimens. Post-transplant prescription of glucocorticoids, calcineurin inhibitors and mTOR inhibitors are associated with increased lipid concentrations. The existence of diabetes mellitus prior to or following a liver transplant is associated with shorter times of useful allograft function. A cycle involving Smad, TGF beta, m-TOR and toll-like receptors has been identified in the contribution of rejection and aging of allografts. Glucocorticoids (prednisone) and calcineurin inhibitors (cyclosporine and tacrolimus) induce hyperglycemia associated with insulin resistance. Azathioprine, mycophenolate and prednisone are associated with lipogenesis. mTOR inhibitors (rapamycin) are used to decrease doses of atherogenic agents used for immunosuppression. Post-transplant medication management must balance immune suppression and glucose and lipid control. Concerns regarding rejection often override those relative to systemic and organ vascular aging and survival. This review focuses attention on the underlying mechanism of relationships between glycemia/lipidemia control, transplant rejection and graft aging.

Tacrolimus-why pharmacokinetics matter in the clinic.

The calcineurin inhibitor (CNI) Tacrolimus (Tac) is the most prescribed immunosuppressant drug after solid organ transplantation. After renal transplantation (RTx) approximately 95% of recipients are discharged with a Tac-based immunosuppressive regime. Despite the high immunosuppressive efficacy, its adverse effects, narrow therapeutic window and high intra- and interpatient variability (IPV) in pharmacokinetics require therapeutic drug monitoring (TDM), which makes treatment with Tac a major challenge for physicians. The C/D ratio (full blood trough level normalized by daily dose) is able to classify patients receiving Tac into two major metabolism groups, which were significantly associated with the clinical outcomes of patients after renal or liver transplantation. Therefore, the C/D ratio is a simple but effective tool to identify patients at risk of an unfavorable outcome. This review highlights the challenges of Tac-based immunosuppressive therapy faced by transplant physicians in their daily routine, the underlying causes and pharmacokinetics (including genetics, interactions, and differences between available Tac formulations), and the latest data on potential solutions to optimize treatment of high-risk patients.

Calcineurin signaling promotes takotsubo syndrome

Takotsubo syndrome (TTS) is an acute heart failure syndrome that mimics the symptoms of acute myocardial infarction and is often preceded by emotional and/or physical stress. There is currently no treatment for TTS. Here we show that injection of 2.5 mg kg−1 of epinephrine (EPI) into mice recapitulates numerous features of human TTS, including increased myocardial damage and mortality in males. Gene set enrichment analysis of myocardial RNA sequencing after EPI injection revealed significant enrichment of calcineurin-dependent pro-inflammatory gene networks, which was more pronounced in male than in female mice, in agreement with observed sex discrepancies in the mouse phenotype. An increase in calcineurin activity was detected in the circulating cells of patients with TTS, suggesting a systemic nature of the syndrome. Preventive and therapeutic treatment of mice injected with EPI using calcineurin inhibitors cyclosporine and tacrolimus improved heart function and reduced myocardial injury. Our findings suggest that calcineurin inhibition could be a potential therapy for TTS.

Long Term Complications of Immunosuppression Post Liver Transplant

Improvement in immunosuppression has led to a remarkable improvement in short-term and long-term outcomes post-liver transplant (LT). However, with improvements in long-term survival, complications related to immunosuppressive drugs, either directly or indirectly, have also increased. The adverse events could be drug-specific, class-specific, or generic. Calcineurin inhibitors (cyclosporine and tacrolimus) are the backbone of the immunosuppression after LT and the main culprit associated with most of the complications, including renal failure, post-transplant diabetes mellitus (PTDM), and metabolic syndrome. Steroids are also implicated in the development of diabetes, osteoporosis, and metabolic syndrome post-LT. The development of infections and de novo malignancies (DNMs) is a generic effectlinked to the overall cumulative immunosuppression. The development of these complications significantly hampers the quality of life and leads to increased morbidity and mortality post-LT. Thus, it is important to minimize the cumulative immunosuppression dosewhile simultaneously preventing allograft rejection. This review provides up-to-date, comprehensive knowledge of the complications of long-term immunosuppression post-LT along with associated risk factors and strategies to minimize the risk of complications.

Beneficial Effects of Tacrolimus on Brain-Death-Associated Right Ventricular Dysfunction in Pigs.

Right ventricular (RV) dysfunction remains a major problem after heart transplantation and may be associated with brain death (BD) in a donor. A calcineurin inhibitor tacrolimus was recently found to have beneficial effects on heart function. Here, we examined whether tacrolimus might prevent BD-induced RV dysfunction and the associated pathobiological changes. After randomized tacrolimus (n = 8; 0.05 mg·kg-1·day-1) or placebo (n = 9) pretreatment, pigs were assigned to a BD procedure and hemodynamically investigated 1, 3, 5, and 7 h after the Cushing reflex. After euthanasia, myocardial tissue was sampled for pathobiological evaluation. Seven pigs were used as controls. Calcineurin inhibition prevented increases in pulmonary vascular resistance and RV-arterial decoupling induced by BD. BD was associated with an increased RV pro-apoptotic Bax-to-Bcl2 ratio and RV and LV apoptotic rates, which were prevented by tacrolimus. BD induced increased expression of the pro-inflammatory IL-6-to-IL-10 ratio, their related receptors, and vascular cell adhesion molecule-1 in both the RV and LV. These changes were prevented by tacrolimus. RV and LV neutrophil infiltration induced by BD was partly prevented by tacrolimus. BD was associated with decreased RV expression of the β-1 adrenergic receptor and sarcomere (myosin heavy chain [MYH]7-to-MYH6 ratio) components, while β-3 adrenergic receptor, nitric oxide-synthase 3, and glucose transporter 1 expression increased. These changes were prevented by tacrolimus. Brain death was associated with isolated RV dysfunction. Tacrolimus prevented RV dysfunction induced by BD through the inhibition of apoptosis and inflammation activation.

#4394TACROLIMUS BUT NOT VOCLOSPORIN INHIBITS KIDNEY TUBULAR CALCIUM AND MAGNESIUM REABSORPTION IN RATS AT CLINICALLY THERAPEUTIC DOSES

Abstract Background and Aims Clinically, the calcineurin inhibitor tacrolimus frequently causes hypercalciuria and hypomagnesemia by inhibiting kidney tubular calcium and magnesium reabsorption. Voclosporin, a novel calcineurin inhibitor approved in the USA and Europe for the treatment of adults with active lupus nephritis, has fewer side-effects including less hypomagnesemia. However, the differences between the kidney tubular effects of tacrolimus and voclosporin are unknown. To address this, we compared the effects of tacrolimus, voclosporin, and vehicle in rats. Method Tacrolimus (0.5 mg/kg) and voclosporin (0.5 mg/kg) were administrated by daily intraperitoneal injections in male Wistar rats and were compared against vehicle (Cremophor EL: 95% ethanol:saline (5:5:90, v:v:v)) for 28 days (n = 8–9/group). Dosages were determined based on pharmacokinetic studies in rats and aimed to achieve the area under the concentration-time curve observed in clinical studies. At day 18, blood and 24 h urine were collected to measure trough levels of the drugs and to analyze the fractional excretions of calcium and magnesium. At sacrifice, kidneys were harvested for immunoblotting of tubular proteins. Results Both tacrolimus and voclosporin reached clinically therapeutic doses with trough levels of 2.4 μg/L ± 0.6 μg/L and 25.8 μg/L ± 9.6 μg/L, respectively. Compared to vehicle, tacrolimus caused significantly higher fractional excretions of calcium (+348% ± 127%, P &amp;lt; 0.001) and magnesium (+60% ± 38%, P &amp;lt; 0.01) and also caused hypomagnesemia (plasma magnesium 0.65 mmol/L ± 0.04 mmol/L vs. 0.81 mmol/L ± 0.02 mmol/L, P &amp;lt; 0.001). Compared to vehicle, voclosporin only caused a slight, but non-statistically significant, increase in fractional calcium excretion (+ 44% ± 38%, P = 0.08) and did not cause higher fractional magnesium excretion (+5% ± 30%, P = 0.96) or hypomagnesemia (plasma magnesium 0.8 mmol/L ± 0.04 mmol/L, P = 0.9). Compared to vehicle, tacrolimus caused an 11-fold decrease in the protein abundance of the cytosolic calcium-binding protein calbindin-D28K and a 2-fold decrease in the abundance of the sodium-chloride cotransporter (NCC). In contrast, voclosporin did not decrease the protein abundances of calbindin-D28K and NCC. No differences were observed between vehicle, tacrolimus, and voclosporin in the calcium channel TRPV5 and magnesium channel TRPM6 (Figure 1). Conclusion In contrast to the calcineurin inhibitor tacrolimus, voclosporin does not inhibit the kidney tubular reabsorption of calcium and magnesium and therefore does not cause hypercalciuria or hypomagnesemia. A possible explanation for this difference is that tacrolimus but not voclosporin affects tubular transport in the distal convoluted tubule, which was further supported by the selective inhibition of calbindin-D28K and NCC by tacrolimus. Our data show that tubulotoxicity of tacrolimus is not apparent with voclosporin treatment, at clinically relevant doses.

#3370 RETURN TO DIALYSIS AFTER KIDNEY TRANSPLANTATION, A REALITY OF TODAY: DESCRIBING OUR EXPERIENCE

Abstract Background and Aims Longer survival in renal transplantation means an increase in the number of patients who return to dialysis after graft loss. There is little literature about the management of immunosupression(IS) in these patients and the complications derived from its maintenance and its withdrawal/reduction. Method We conducted a retrospective study involving a cohort of patients who returned to dialysis after graft failure at Doce de Octubre Hospital from 2015 to 2022. We analyzed baseline characteristics, IS withdrawal scheme, and the complications derived in the 27 months following the restart of dialysis. Results A total of 50 patients were enrolled in the study: 58% male, 86% hypertensive, 30% diabetic and 52% with heart disease. The median age at transplant was 41.5 (33.7-53.2). 70% of donations were in brain death, 18% asystole and 10% alive. The duration of the graft was 8.5 years (5,14), 96% of patients developed anti-HLA antibodies and 40% suffered active rejection. Upon restarting dialysis, all the patients were receiving IS: 84% calcineurin inhibitors (CNI) (tacrolimus, cyclosporine), 58% antimetabolites (mycophenolate, azathioprine), and 10% mTOR inhibitors (everolimus). Haemodialysis was performed in 70% of patients through central venous catheterization in 68.6%. The median time to stop IS was 10 months (6,19). Between the first and the third month, imTOR [0(0.4)] and antimetabolite [1(0.3)] were finalized. Discontinuance of CNI and steroids was at 2 months (1,8) and 8 months (3,15.7) respectively. As complications derived of IS, 64% of patients developed serious infection and 12% were diagnosticated of neoplasms. On the other hand, eighteen patients presented immunological intolerance to the graft, 100% requiring an increase of steroids, 72.2% percutaneous embolization and finally 50% require a transplantectomy. The rate of immunological intolerance, embolization and transplantectomy was higher in patients with withdrawal IS during the first year. Patients on haemodialysis (HD) had higher rate of graft intolerance compared to peritoneal dialysis (PD) (40.5% vs 23%), attributable to early suspension of IS (62% before the first year), but similar rate of infection (61.5%PD, 64.8%HD). At 27 months (14.5,44.2) of follow-up after returning dialysis, 64% of patients remained on dialysis (30% on waiting list for a second kidney transplantation), 28% were retransplanted, and 8% were died. Conclusion Most of transplant recipients returned to haemodialysis through a venous catheter. Withdrawal of immunosuppression was performed on a median of 10 months, faster in mTOR and antimetabolites, and more progressive in CNI and steroids. Stop IS before the first year is more common in haemodialysis group and it is associated with a higher rate of graft intolerance. Finally we want to highlight the significant percentage of embolizations in our hospital, that let us avoid a 12.2% of the transplantectomies.

#2989 SELECTIVE RENAL DISPOSITION OF THE CALCINEURIN INHIBITORS VOCLSOPORIN, CYCLOSPORINE, AND TACROLIMUS

Abstract Background and Aims The calcineurin inhibitors (CNI) cyclosporine (CSA) and tacrolimus (TAC) were revolutionary immunosuppressants when first introduced for solid organ transplantation in the 1980s. Voclosporin (VCS), a novel CNI, recently became the first oral therapy approved in the United States, Great Britain, and Europe for the treatment of active lupus nephritis based on positive results from Phase 2 and 3 clinical trials. Unlike CSA and TAC, VCS has demonstrated a consistent pharmacokinetic and pharmacodynamic profile, eliminating the need for therapeutic drug monitoring. Further, VCS is associated with a more favorable metabolic profile and has not been associated with electrolyte disturbances. Emerging evidence indicates small molecule therapeutics may display differential disposition within organ tissues. This suggests that CNIs may be differentially distributed and retained in the kidney, potentially explaining the difference in their efficacy and safety profiles. To evaluate renal disposition of CSA, TAC, and VCS, we assessed in mice and humans the disposition of each CNI in the kidney relative to its systemic drug exposure. Method Single 30 mg/kg doses of CSA, TAC and VCS were administered intravenously to mice. Following intravenous administration, kidneys were collected at 15 minutes, 30 minutes, 1 hour and 2 hours, flash frozen in liquid nitrogen, and stored at −20 °C until sectioning. Sections of 10 μm kidney tissue were mounted on indium tin oxide coated glass slides. Matrix of 10 mg/mL α-Cyano-4-hydroxycinnamic acid in 85% acetonitrile/13% ethanol + 2% water + 0.1% trifluoroacetic acid was sprayed on the tissue using an HTX tissue sprayer, dried for 10 minutes in the vacuum, and subjected to Matrix-assisted Laser Desorption and Ionization Mass Spectrometry Imaging (MALDI-MSI). The systemic and renal clearance in humans of CSA and TAC were obtained from the literature; pharmacokinetic data on VCS was obtained from data on file. Renal secretion of each drug was compared to its expected passive filtration based on glomerular filtration rate (GFR), fraction unbound in plasma (fu), and respective systemic drug exposure. Results MALDI-MSI demonstrated significantly higher concentrations of drug and more diffuse tissue disposition of CSA in mouse kidney compared to VCS (Figure 1). CSA was retained in all kidney tissues up to 2 hours post-administration. Higher concentrations and more diffuse disposition of TAC was also noted compared to VCS at 15 and 30 minutes; TAC was distinctively retained in the cortex and medulla. VCS had moderate distribution in the cortex and was rapidly excreted with low levels of drug present in the kidney after 1 hour. According to published data, CSA has a measured renal clearance of 1.48 mL/min in healthy human subjects, representing approximately 10% of expected passive filtration of 12.5 mL/min (Table 1). TAC has a renal clearance of 0.014 mL/min representing &amp;lt;2% of expected passive filtration of 1.25 mL/min. VCS has a renal clearance of 7.82 mL/min representing approximately 200% of its expected passive filtration rate of 3.75 mL/min. Conclusion MALDI-MSI revealed differential retention and distribution of CSA, TAC and VCS in mice, consistent with their respective renal clearances in humans. Higher drug exposure and &amp;gt;90% renal reabsorption was observed for both CSA and TAC in this study, whereas the renal handling of VCS suggested a significant component of tubular secretion. The higher rate of secretion and lower overall exposure of kidney tissue to VCS may be associated with an improved safety profile when compared to the more diffuse distribution and greater renal retention of CSA and TAC.

An analysis of the efficacy of graft-versus-host disease prophylaxis with post-transplant cyclophosphamide in children with acute myeloid leukemia following allogeneic hematopoietic stem cell transplantation from HLA-matched and partially-matched unrelated donors

An analysis of the efficacy of graft-versus-host disease prophylaxis with post-transplant cyclophosphamide in children with acute myeloid leukemia following allogeneic hematopoietic stem cell transplantation from HLA-matched and partially-matched unrelated donors

Immunosuppressant drugs and quality-of-life outcomes in kidney transplant recipients: An international cohort study (EU-TRAIN).

Introduction: Patient-Reported Outcomes (PRO) integrate a wide range of holistic dimensions that arenot captured within clinical outcomes. Particularly, from induction treatment to maintenance therapy, patient quality-of-life (QoL) of kidney transplant recipients have been sparsely investigated in international settings. Methods: In a prospective, multi-centric cohort study, including nine transplant centers in four countries, we explored the QoL during the year following transplantation using validated elicitation instruments (EQ-5D-3L index with VAS) in a population of kidney transplant patients receiving immunosuppressive therapies. Calcineurin inhibitors (tacrolimus and ciclosporin), IMPD inhibitor (mycophenolate mofetil), and mTOR inhibitors (everolimus and sirolimus) were the standard-of-care (SOC) medications, together with tapering glucocorticoid therapy. We used EQ-5D and VAS data as QoL measures alongside descriptive statistics at inclusion, per country and hospital center. We computed the proportions of patients with different immunosuppressive therapy patterns, and using bivariate and multivariate analyses, assessed the variations of EQ-5D and VAS between baseline (i.e., inclusion Month 0) and follow up visits (Month 12). Results: Among 542 kidney transplant patients included and followed from November 2018 to June 2021, 491 filled at least one QoL questionnaire at least at baseline (Month 0). The majority of patients in all countries received tacrolimus and mycophenolate mofetil, ranging from 90.0% in Switzerland and Spain to 95.8% in Germany. At M12, a significant proportion of patients switched immunosuppressive drugs, with proportion varying from 20% in Germany to 40% in Spain and Switzerland. At visit M12, patients who kept SOC therapy had higher EQ-5D (by 8 percentage points, p < 0.05) and VAS (by 4 percentage points, p < 0.1) scores than switchers. VAS scores were generally lower than EQ-5D (mean 0.68 [0.5-0.8] vs. 0.85 [0.8-1]). Discussion: Although overall a positive trend in QoL was observed, the formal analyses did not show any significant improvements in EQ-5D scores or VAS. Only when the effect of a therapy use was separated from the effect of switching, the VAS score was significantly worse for switchers during the follow up period, irrespective of the therapy type. If adjusted for patient characteristics and medical history (e.g., gender, BMI, eGRF, history of diabetes), VAS and EQ-5D delivered sound PRO measures for QoL assessments during the year following renal transplantation.

Clinical Implications and Risk Factors for Erectile Dysfunction in Kidney Transplant: A Single-Center Assessment.

Erectile dysfunction (ED) affects the great majority of people undergoing dialysis and also the majority of patients undergoing kidney transplantation. In this study, we investigated the degree of erectile dysfunction (ED), as well as its prevalence, contributory variables, and overall impact after renal transplant. Adult male kidney transplant patients were the subject of an observational, non-interventional study that was conducted at a single center. Age, time and type ofdialysis before transplantation, comorbidities, factors associated with cardiovascular risk, data on sexual history, physical examination, and laboratory results were among the clinical data we examined. In addition to gathering clinical and demographic characteristics, the International Index of Erectile Function (IIEF) questionnaire was used to evaluate sexual function. A total of 170 renal transplanted patients between 20 and 70 years old (mean age: 45.40±11.5) were included in this study. All of the patients had immunosuppressive treatment with a calcineurin inhibitor (cyclosporine or tacrolimus) and had a normalglomerular filtration rate (GFR). The prevalence of sexual dysfunction increased with age (42.6% of patients under 40, 47.4% of patients in the 40-60 age group, and 78.9% of patients over 60). Mild, moderate, and severe ED was noted in 33.5%, 20.6%, and 10.6% of cases, respectively, and 51 (30%) patients reported having a normal sexual function.While calcium channel blockers (122 cases) were the most commonly used antihypertensive medication and chronic glomerulosclerosis (55.3%) was the most common cause of chronic kidney disease (CKD) before transplantation, none of these variables appear to have affected the severity of erectile dysfunction. The only medications associated with sexual dysfunction were alpha-blockers and aspirin (75 mg)(p=0.026 and p=0.013, respectively). Although kidney transplantation has positive impacts on the quality of life, erectile dysfunction is a frequent condition among patients with renal transplants, and it has an increased frequency with age. In our study, it has been observed that only a small percentage of the research group had a normal sexual function, although most of the patients were young, and that alpha-blockers and aspirin (75 mg) are associated with erectile dysfunction.