Tacrolimus Immunosuppression Research Articles

Measurement of Whole Blood Tacrolimus Concentrations by LC-MS/MS and Immunoassay Methods: Influence of Immediate-Release vs Extended-Release Tacrolimus Formulations.

Therapeutic drug monitoring of the immunosuppressant tacrolimus is commonly performed by immunoassay or LC-MS/MS. Measurement biases between these methodologies have been characterized for immediate-release tacrolimus (IR-tac; Prograf) but have not been performed for extended-release formulations such as Envarsus. These discrepancies can impact patient care, as appropriate dosing is required to maintain therapeutic concentrations and immunosuppression. Validation of a whole-blood LC-MS/MS method for the simultaneous quantification of tacrolimus and its major metabolite, desmethyl tacrolimus, was performed using traceable calibrators (tacrolimus, ERM-DA110a) and quality control (QC) material for tacrolimus and standard material for desmethyl tacrolimus. Tacrolimus concentrations were determined by LC-MS/MS and the ARCHITECT immunoassay in patients receiving either IR-tac or Envarsus for clinical care. External calibration curves for both tacrolimus and desmethyl tacrolimus were linear (R2 > 0.995), and the analytical measurement range (AMR) for tacrolimus spanned from 1.1 to 31.6 ng/mL. Calibrator/QC biases were within 15% of their spiked concentrations throughout the AMR, and within-run imprecision was <10%, except at the lower limit of quantification (n = 25). Between-run imprecision for low, mid, and high QC levels was ≤11% over a 2-week period (n = 5 days). Comparative biases between immunoassay and LC-MS/MS were significantly lower (P = 0.0074) for patients receiving Envarsus (n = 20 specimens) relative to patients receiving IR-tac (n = 32 specimens). Biases between immunoassay and LC-MS/MS tacrolimus measurements in patients receiving immediate-release vs extended-release formulations indicate that their distinct pharmacokinetic profiles impact measurement accuracy. These assay biases should be considered when interpreting tacrolimus concentration measurements.

Unrelated Bone Marrow Transplantation for Chronic Myeloid Leukemia after Liver Transplantation

This report describes the case of a 29-year-old patient with chronic myeloid leukemia in the blast phase who underwent hematopoietic stem cell transplantation (HSCT) after living-donor liver transplantation. Donor selection, conditioning regimens, and graft-versus-host disease (GVHD) prophylaxis are discussed. The patient received a non-myeloablative conditioning regimen and ABO blood group-matched unrelated human leukocyte antigen fully-matched donors. Immunosuppressants tacrolimus and mycophenolate mofetil were administered to prevent GVHD. Maintenance therapy with ponatinib effectively maintained remission. This case highlights the complexities of managing HSCT after solid organ transplantation and suggests strategies for future cases.

Immunosuppressant drug tacrolimus inhibits HUVEC angiogenesis and production of placental growth factor.

Tacrolimus is a cornerstone of immunosuppression in solid organ transplants, but its use is linked with the development of endothelial dysfunction. Pregnant solid organ transplant recipients are four to six times more likely to develop preeclampsia, which is also associated with endothelial dysfunction. Therefore, this in vitro study investigated the acute effects of tacrolimus on the expression of common angiogenic factors related to preeclampsia, and effects on angiogeneis in primary human tissues. Primary human umbilical vein endothelial cells (HUVECs) were exposed to tacrolimus (0, 5, 20, 50ng/mL) for 24h alone, or in combination with tumour necrosis factor (TNF, 10ng/mL) and high dose glucose (25mM). Cell culture concentrations of sFlt-1, PlGF and activin A were measured. In addition, the effect of tacrolimus on markers of endothelial dysfunction and permeability were assessed, as were the effect of tacrolimus on tube formation. Angiogenic factors and mRNA markers of oxidative stress and inflammation were also assessed in primary placental tissue after an acute 24h exposure to tacrolimus. Tacrolimus exposure significantly reduced HUVEC secretion of PlGF, increased production of activin A, andreduced tubular structure formation without impacting cell permeability or viability. There was no change in ICAM1 or VCAM1 expression in HUVECs treated with tacrolimus treatment alone, however co-culture with TNF significantly increased expression of ICAM1 and VCAM1. In placental explants tacrolimus did not change angiogenic factor production or markers of inflammation or oxidative stress. An acute tacrolimus exposure reduced PlGF secretion and impaired angiogenesis in primary endothelial cells, without affecting. These findings provide a potential mechanistic basis for tacrolimus to contribute to the endothelial dysfunction contributing to preeclampsia.

Retention of indoxyl sulfate in different genotypes of ABCC2 may explain variation in tacrolimus pharmacokinetics.

Microbiota-derived toxins indoxyl sulfate and hippuric acid were previously reported to be associated with altered pharmacokinetics of the immunosuppressant tacrolimus in liver transplant recipients, and ABC transporter proteins are likely to be involved in the transport of such substances, but the in vivo role has not been elucidated. The aim of this study was to assess the retention of indoxyl sulfate and hippuric acid in the plasma of liver transplantation subjects carrying different genotypes of ABCB1 and ABCC2 (changes in transporter activity due to genetic variation), and to explore whether genetic variation is involved in altering the relationship between microbe-derived toxins and tacrolimus pharmacokinetics. Liver transplantation subjects treated with the immunosuppressive regimen tacrolimus, corticosteroids, and mycophyolate mofetil were included and divided into normal renal function group and chronic kidney disease group. The plasma concentrations of indoxyl sulfate and hippuric acid in two groups of liver transplantation subjects carrying different genotypes of ABCB1 and ABCC2 were compared. For genotype carriers with significant differences, the Pearson Correlation Coefficient method was further used to investigate the correlation between plasma indoxyl sulfate level and tacrolimus dose-corrected trough concentration in patients with different renal function status. Carriers of the rs717620-24T variant exhibited high plasma indoxyl sulfate retention in patients with normal renal function, and furthermore, chronic kidney disease patients and patients with normal renal function exhibited indoxyl sulfate and tacrolimus in the ABCC2 normal function (β = -0.740, p = 0.020) and reduced function groups (β = -0.526, p = 0.005), respectively, showing a strong correlation with tacrolimus. ABCC2 may be one of the pathways by which tacrolimus pharmacokinetics is altered by indoxyl sulfate.

Patiromer Does Not Alter Tacrolimus Pharmacokinetics in Kidney Transplant Recipients When Administered Three Hours Post-Tacrolimus.

Hyperkalemia is common in kidney transplant (KTx) recipients. Patiromer, a potassium-binding polymer used to treat acute and chronic hyperkalemia, has the potential to bind charged particles in the gastrointestinal tract and thereby potentially affect the absorption of coadministered drugs. The immunosuppressive drug tacrolimus (Tac) has a narrow therapeutic window, is susceptible to drug-drug interactions (DDIs), and a potential gastrointestinal interaction with patiromer could elevate the risk of allograft rejection. We aimed to investigate the potential DDI between patiromer and Tac pharmacokinetics in KTx with hyperkalemia by sampling capillary blood using volumetric absorptive microsampling (VAMS). Thirteen KTx recipients on Tac twice daily (BID) with plasma potassium levels of >4.6 mmol/L were included. Two 12 h Tac pharmacokinetic investigations were performed with and without 8.4 mg patiromer/d for 1 wk. Oral Tac dose remained unchanged and patiromer was administered 3 h after Tac dose. Tac sampling was self-conducted using VAMS after mastering the technique. Ten patients provided 2 evaluable pharmacokinetic profiles. The Tac area under the curve (AUC)0-12 ratio (AUCTac+patiromer/AUCTac) was 0.99 (90% confidence interval [CI], 0.86-1.14), and the Cmax ratio was 1.01 (90% CI, 0.86-1.19). Tac C0 and C12 fulfilled the bioequivalence criteria with a ratio of 0.98 (90% CI, 0.90-1.07) and 0.93 (90% CI, 0.83-1.04), respectively. When administered 3 h after the Tac morning dose, patiromer has no clinically relevant impact on Tac pharmacokinetics. We demonstrate that VAMS is a well-suited sampling method to simplify the execution of DDI studies.

Abstract 4138738: Clinical Evidence of Immune Response to Transplanted Allogeneic iPS Cell-Derived Cardiomyocytes

Background&amp;Purpose: The clinical application of cell transplantation therapy utilizing induced pluripotent stem cells (iPS cells) for heart failure is progressing, with the primary strategy being the use of pre-prepared allogeneic iPS cells. The immune response to these transplanted cells is crucial and may affect therapeutic efficacy, necessitating the use of immunosuppressive drugs. However, detailed clinical reports on immune responses are sparse. This study aims to analyze the immune response to transplanted cells in clinical iPS cell-derived cardiomyocyte (iPSC-CM) transplants and examine the correlation between immune response and therapeutic efficacy. Methods: In the "Phase 1 multicenter clinical trial of transplantation of iPSC-CMs for ischemic cardiomyopathy" (https://jrct.niph.go.jp/en-latest-detail/jRCT2053190081), conducted as the First-in-Human trial, the immune response to transplanted cells was analyzed in four cases at our hospital. Comprehensive analysis of anti-human leukocyte antigen (HLA) antibodies in serum and single-cell RNA sequencing in peripheral blood mononuclear cells was performed to investigate their relationship with therapeutic effects on cardiac function. Results: Patients received immunosuppressive drugs (tacrolimus, mycophenolate mofetil, and steroids) for 3 months post-transplantation, followed by a 1-year follow-up. In all cases, an increase in transplant cell HLA-specific antibodies was observed after discontinuing immunosuppressive drugs (Figure 1 and 2). Single-cell analysis revealed a decrease in immunocompetent cells in peripheral blood during immunosuppressive therapy. Cardiac function analysis showed improvements in all cases except Case 2 (Figure 3), where pre-existing anti-HLA-DQ antibodies were present before transplantation. Conclusions: No immune response to the transplanted cells was observed during immunosuppressive therapy. In a case with limited therapeutic response, pre-existing antibodies to transplanted cells were detected, potentially impacting the therapeutic outcome.

An Immune-Independent Mode of Action of Tacrolimus in Promoting Human Extravillous Trophoblast Migration Involves Intracellular Calcium Release and F-Actin Cytoskeletal Reorganization.

We have previously reported that the calcineurin inhibitor macrolide immunosuppressant Tacrolimus (TAC, FK506) can promote the migration and invasion of the human-derived extravillous trophoblast cells conducive to preventing implantation failure in immune-complicated gestations manifesting recurrent implantation failure. Although the exact mode of action of TAC in promoting implantation has yet to be elucidated, the integral association of its binding protein FKBP12 with the inositol triphosphate receptor (IP3R) regulated intracellular calcium [Ca2+]i channels in the endoplasmic reticulum (ER), suggesting that TAC can mediate its action through ER release of [Ca2+]i. Using the immortalized human-derived first-trimester extravillous trophoblast cells HTR8/SVneo, our data indicated that TAC can increase [Ca2+]I, as measured by fluorescent live-cell imaging using Fluo-4. Concomitantly, the treatment of HTR8/SVneo with TAC resulted in a major dynamic reorganization in the actin cytoskeleton, favoring a predominant distribution of cortical F-actin networks in these trophoblasts. Notably, the findings that TAC was unable to recover [Ca2+]i in the presence of the IP3R inhibitor 2-APB indicate that this receptor may play a crucial role in the mechanism of action of TAC. Taken together, our results suggest that TAC has the potential to influence trophoblast migration through downstream [Ca2+]i-mediated intracellular events and mechanisms involved in trophoblast migration, such as F-actin redistribution. Further research into the mono-therapeutic use of TAC in promoting trophoblast growth and differentiation in clinical settings of assisted reproduction is warranted.

Enhanced BMP Signaling Alters Human β-Cell Identity and Function.

Inflammation contributes to the pathophysiology of diabetes. Identifying signaling pathways involved in pancreatic β-cell failure and identity loss can give insight into novel potential treatment strategies to prevent the loss of functional β-cell mass in diabetes. It is reported earlier that the immunosuppressive drug tacrolimus has a detrimental effect on human β-cell identity and function by activating bone morphogenetic protein (BMP) signaling. Here it is hypothesized that enhanced BMP signaling plays a role in inflammation-induced β-cell failure. Single-cell transcriptomics analyses of primary human islets reveal that IL-1β+IFNγ and IFNα treatment activated BMP signaling in β-cells. These findings are validated by qPCR. Furthermore, enhanced BMP signaling with recombinant BMP2 or 4 triggers a reduced expression of key β-cell maturity genes, associated with increased ER stress, and impaired β-cell function. Altogether, these results indicate that inflammation-activated BMP signaling is detrimental to pancreatic β-cells and that BMP-signaling can be a target to preserve β-cell identity and function in a pro-inflammatory environment.

7635 Severe Osteoporosis in a Patient with Heterotopic Calcification: A Case Report

Abstract Disclosure: D. Salih Bacha: None. L.Z. Khan: None. Background: While osteoporosis and heterotopic ossification (HO) are distinct conditions affecting bone health, their coexistence poses intriguing clinical challenges. Osteoporosis, characterized by increased bone fragility, typically results from various factors such as aging, steroid use, or malabsorption. HO is a condition where bone forms abnormally in soft tissues. Risk factors that predispose to HO include male sex, spinal cord injury, trauma, surgery, and genetic factors. Treatment of HO is typically surgical resection and NSAIDs. Initial evidence supported the use of bisphosphonates for preventing ectopic bone formation post-trauma, but recent data failed to show significant benefit in HO prevention. This case presents a patient with unique challenges of both HO and bone fragility with multiple severe vertebral fractures. Case: A 44-year-old male patient had a major motor vehicle accident necessitating multiple recurrent abdominal surgeries. During one exploratory laparotomy, diffuse mesenteric calcifications were noted, indicative of HO. A baseline Dual X-ray Absorptiometry (DXA) scan revealed bone density of 1.003 g/cm2 and 0.788 g/cm2 at the spine and femoral neck, respectively, concerning for osteopenia. He was started on zoledronic acid in preparation for upcoming intestinal transplant. Few months after the transplant, he was started on daily tacrolimus and hydrocortisone for immunosuppression. Within months, he experienced sudden back pain while riding an elevator, and was found to have acute fractures in T8 and T9 vertebrae. A repeat DXA scan showed a further decline in bone density to 0.909 g/cm2 and 0.748 g/cm2 at the spine and femoral neck, respectively. Within a year, additional fractures occurred in the thoracic and lumbar spine (T10, T11, T12, L1, L2, L3, and L4), requiring multiple kyphoplasty interventions. Over time, worsening kyphosis, back pain, and height loss occurred, significantly affecting the patient's quality of life. He continued receiving yearly zoledronic acid infusions and underwent regular DXA scans, which revealed mild improvement in his bone density. Currently, there are no established guidelines specifying the optimal duration for bisphosphonate treatment in such cases. Therefore, our individualized treatment plan involves a tentative 10-year course of bisphosphonate treatment with yearly assessment of bone mineral density. Conclusion: Although the patient had some risk factors for osteoporosis, including daily steroid and tacrolimus use, the severity and frequency of his fractures suggested a potential synergy between osteoporosis and HO, where the formation of heterotopic calcifications may have been exacerbating his bone loss. The coexistence of osteoporosis and HO in this patient underscores the need for individualized care and establishment of treatment guidelines in patients with multiple bone disorders. Presentation: 6/3/2024

Clinical drug interactions between voriconazole and 38 other drugs: a retrospective analysis of adverse events.

Voriconazole (VRZ) is involved in a variety of drug‒drug interactions (DDIs), but few studies have reported adverse events (AEs) associated with the DDIs of VRZ. The primary goal of this study was to analyse the potential risk factors for AEs caused by DDIs between VRZ and other drugs via the OpenVigil FDA platform and to provide a reference for preventing VRZ DDIs and monitoring clinically related adverse drug events. A retrospective pharmacovigilance study was conducted to investigate the AEs related to DDIs between VRZ and four categories of drugs: proton pump inhibitors (PPIs), non-steroidal anti-inflammatory drugs (NSAIDs), immunosuppressants, and other antibacterial drugs. AE information for the target drugs from the first quarter of 2004 to the third quarter of 2022 was downloaded from the OpenVigil FDA data platform. Four frequency statistical models-the reporting ratio method, Ω shrinkage measure model, combination risk ratio model, and the chi-square statistics model-were used to analyse the AEs related to DDIs and evaluate the correlation and influence of sex and age between the drug(s) and the target AEs detected. A total of 38 drugs were included, with 262 AEs detected by at least one of the four models and 48 AEs detected by all four models. Some 77 detected AEs were significantly positively correlated with DDIs and were related to higher reporting rates of AEs than when used alone. Graft-versus-host disease was the AE that had the strongest correlation with the drug interaction between VRZ and immunosuppressants (tacrolimus, mycophenolate mofetil, cyclophosphamide, and cyclosporine), and multiple organ dysfunction syndrome was correlated with VRZ in combination with other antibacterial drugs (linezolid, meropenem, cefepime, and vancomycin). Significant sex and age differences in the target AEs were detected for five and nine target drugs, respectively. For VRZ in combination with linezolid, aggravated conditions and respiratory failure should be given more attention in male patients, and mycophenolate mofetil and respiratory failure in female patients. When conditions are aggravated, febrile neutropenia and septic shock should be of particular concern in patients over 18years of age who use VRZ in combination with ceftazidime, ciprofloxacin, or cytarabine. In patients aged under 18, septic shock should be considered when VRZ is used in combination with meropenem and dexamethasone. AEs related to DDIs should receive more attention when VRZ is used in combination with PPIs (renal impairment), NSAIDs (constipation and renal failure), immunosuppressants (graft versus host disease, septic shock) and other antibacterial drugs (multiple organ dysfunction syndrome, febrile neutropenia, and respiratory failure). Considering the influence of sex and age differences in VRZ DDIs, these factors need to be considered when assessing the risk of AEs in patients receiving VRZ and other drugs.

Pharmacovigilance in the Age of Legalized Cannabis: Using Social Media to Monitor Drug-Drug Interactions Between Immunosuppressants and Cannabis-Derived Products.

A clinical trial of Epidiolex®, the only US FDA-approved cannabis-derived consumer product (CDP), discovered an interaction with an immunosuppressant (tacrolimus) that led to drug toxicity, highlighting the unique intersection of prescription and commonly unregulated consumer products. We aimed to identify if similar drug-drug interactions (DDIs) are occurring among the consumer CDP market, even though they cannot be identified through trials. We searched Reddit for subreddits related to CDPs or health, resulting in 63,561,233 posts. From these, we identified 190 posts discussing both immunosuppressants and CDPs. Two blinded investigators evaluated the following. (1) Was there a concern about a potential DDI between consumer CDPs and immunosuppressants? (2) Was there a unique adverse event attributed to a DDI between consumer CDPs and immunosuppressants? Of these, 66 posts (35%) expressed concern about a potential DDI, such as "Hey, my partner wants to try my edibles … she's on Prograf [tacrolimus] and wants to talk to a stoner who's had a heart transplant." Four posts (2%) reported a unique DDI, such as "I have clinical results that are semi-anecdotal, showing the coordination to my halting substance use … It's the CBD. Shot my prograf to 30 at like 4mg." Two of the four reported DDIs are similar to those first reported for Epidiolex. The remaining two reported DDIs include a potential cannabidiol (CBD)/sirolimus or delta-9-tetrahydrocannabinol (THC)/sirolimus interaction and a THC/tacrolimus interaction, both resulting in drug toxicity. This case study is the first to report on DDIs involving consumer CDPs, including both CBD and THC products, as well as a broader class of immunosuppressants. This demonstrates the risks associated with using consumer CDPs alongside prescription medications while highlighting the need for development of increased surveillance to monitor consumer CDPs for drug safety signals, as well as comprehensive regulations that take into account the unique characteristics of the consumer marketplace.

Belatacept Versus Tacrolimus for Kidney Transplant Recipients of Deceased Donors With Acute Kidney Injury: US National Database Study.

It is unclear whether kidney grafts from deceased donors with acute kidney injury (AKI) are more vulnerable to calcineurin inhibitor nephrotoxicity, and whether de novo use of belatacept is more beneficial than tacrolimus for recipients of these types of kidney transplants. In this retrospective cohort study using the US Organ Procurement and Transplantation Network database, we created 1:4 matches with highly similar characteristics for recipients of AKI-donor kidneys receiving belatacept versus tacrolimus for initial maintenance immunosuppression and compared outcomes for graft function, patient and graft survival, and rejection. The matched cohort consisted of 567 and 2268 recipients administered belatacept and tacrolimus, respectively. Posttransplant estimated glomerular filtration rate was significantly higher in the belatacept group at 6 mo (58.2 ± 24.2 versus 54.6 ± 21.6 mL/min/1.73 m2, P < 0.001); however, the between-group difference did not reach statistical significance at 12 mo (57.2 ± 24.3 versus 55.7 ± 22.2 mL/min/1.73 m2, P = 0.057). Median follow-up periods were 3.2 and 3.1 y for patient and graft survival, respectively. There were no significant differences between belatacept versus tacrolimus for mortality (hazard ratio 1.18 [95% confidence interval, 0.95-1.47], P = 0.14) or death-censored graft failure (hazard ratio 1.17 [0.85-1.61], P = 0.33). Rejection rate within 12 mo was significantly higher in the belatacept group (13% versus 7%, P < 0.001). In this matched cohort study, initial use of belatacept for AKI-donor kidney recipients was associated with small benefits in early graft function when compared with tacrolimus. Although rejection risk was significantly higher in recipients administered belatacept, patient and graft survival were not significantly different between groups.

Immunosuppressant therapy averts rejection of allogeneic FKBP1A-disrupted CAR-T cells

Chimeric antigen receptor (CAR) Tcells from allogeneic donors promise "off-the-shelf" availability by overcoming challenges associated with autologous cell manufacturing. However, recipient immunologic rejection of allogeneic CAR-T cells may decrease their invivo lifespan and limit treatment efficacy. Here, we demonstrate that the immunosuppressants rapamycin and tacrolimus effectively mitigate allorejection of HLA-mismatched CAR-T cells in immunocompetent humanized mice, extending their invivo persistence to that of syngeneic humanized mouse-derived CAR-T cells. In turn, genetic knockout (KO) of FKBP prolyl isomerase 1A (FKBP1A), which encodes a protein targeted by both drugs, was necessary to confer CD19-specific CAR-T cells (19CAR) robust functional resistance to these immunosuppressants. FKBP1AKO 19CAR-T cells maintained potent invitro functional profiles and controlled invivo tumor progression similarly to untreated 19CAR-T cells. Moreover, immunosuppressant treatment averted invivo allorejection permitting FKBP1AKO 19CAR-T cell-driven B cell aplasia. Thus, we demonstrate that genome engineering enables immunosuppressant treatment to improve the therapeutic potential of universal donor-derived CAR-T cells.

Effect of Immunosuppressive Therapy After Liver Transplantation and the Relationship Between Changes in the Gut Microbiome and Graft Rejection

Solid organ transplantation, particularly liver transplantation, necessitates the use of immunosuppressive therapy to prevent organ rejection. However, these agents profoundly affect the gut microbiota, whose altered state can significantly impact transplant outcomes. This review synthesizes current knowledge on the interactions between immunosuppressants and the gut microbiota and explores the mechanisms by which these interactions affect graft survival and rejection. Immunosuppressive drugs, including cyclosporine, tacrolimus, sirolimus, mycophenolate mofetil, prednisone, and azathioprine, are known to cause dysbiosis by decreasing microbial diversity and favoring pathogenic bacteria and fungi. This disruption can lead to increased susceptibility to infections, chronic inflammation, impaired drug metabolism, and direct effects on graft rejection. The review also discusses the potential of modifying the gut microbiota to improve transplant outcomes through dietary interventions, probiotics, prebiotics, and fecal microbiota transplantation (FMT). These interventions aim to restore a healthy microbial balance, enhance immune tolerance, and reduce the incidence of graft rejection. The paper highlights the need for integrated approaches that consider the microbiome’s role in transplantation and outlines future directions for research and clinical practice, aiming to optimize the management of transplant recipients. By understanding and manipulating the gut microbiome, new therapeutic strategies could revolutionize transplant medicine, reducing complications and improving the quality of life for recipients.

Standardization via Post Column Infusion-A Novel and Convenient Quantification Approach for LC-MS/MS.

Mass spectrometry (MS) is a widely used analytical technique including medical diagnostics, forensic toxicology, food and water analysis. The gold standard for quantifying compounds involves using stable isotope-labeled internal standards (SIL-IS). However, when these standards are not commercially available, are prohibitively expensive, or are extremely difficult to synthesize, alternative external quantification techniques are employed. We hereby present a novel, convenient and cheap quantification approach-quantification via post column infusion (PCI). As a proof of concept, we demonstrated PCI quantification for the immunosuppressant tacrolimus in whole blood using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The validation results met the criteria according to the guideline on bioanalytical method validation of the European Medicine Agency (EMA), achieving imprecisions and inaccuracies with coefficient of variation and relative bias below 15%. Anonymized and leftover whole blood samples from immunosuppressed patients receiving tacrolimus were used for method comparison (PCI quantification vs. conventional internal standard (IS) quantification). Both methods showed strong agreement with a Pearson correlation coefficient of r = 0.9532. This novel PCI quantification technique (using the target analyte itself) expands the quantification options available in MS, providing reliable results, particularly when internal standards are unavailable or unaffordable. With the current paper, we aim to demonstrate that our innovative PCI technique has great potential to overcome practical issues in quantification and to provide guidance on how to incorporate PCI in existing or new LC-MS methods. Moreover, this study demonstrated a more convenient method for correcting matrix effects in comparison to alternative PCI techniques.

Removing the physician from the equation: Patient-controlled, home-based therapeutic drug self-monitoring of tacrolimus.

The dosing of tacrolimus, which forms the backbone of immunosuppressive therapy after kidney transplantation, is complex. This is due to its variable pharmacokinetics (both between and within individual patients), narrow therapeutic index, and the severe consequences of over- and underexposure, which may cause toxicity and rejection, respectively. Tacrolimus is, therefore, routinely dosed by means of therapeutic drug monitoring (TDM). TDM is performed for as long as the transplant functions and frequent and often lifelong sampling is therefore the rule. This puts a significant burden on patients and transplant professionals and is associated with high healthcare-associated costs. Furthermore, by its very nature, TDM is reactive and has no predictive power. Finally, the current practice of TDM does not foresee in an active role for patients themselves. Rather, the physician or pharmacist prescribes the next tacrolimus dose after obtaining the concentration measurement test results. In this article, we propose a strategy of patient-controlled, home-based, self-TDM of the immunosuppressant tacrolimus after transplantation. We argue that with the combined use of population tacrolimus pharmacokinetic models, home-based sampling by means of dried blood spotting and implementation of telemedicine, this may become a feasible approach in the near future.

#2362 Clinical utility Anti-human T-lymphocyte Immunoglobulin (ATLG) as an induction agent in a living donor kidney transplantation: 5-year follow-up data

Abstract Background and Aims The usage of induction agents for living donor kidney transplants in India is varied. Polyclonal antibodies currently in use are anti-thymocyte globulin (ATG) and anti-T-lymphocyte globulin (ATLG). The role and dose of ATLG need to be defined. This study is focused on ATLG usage and the outcome with long-term follow-up. Method This is an analysis of 206 patients who received ATLG as an induction agent from 2017 to 2023. Patients received triple immunosuppression therapy: Tacrolimus, Mycophenolate Mofetil (MMF), and prednisolone for maintenance immunosuppression. Results A total of 206 patients received ATLG as an induction agent for living donor kidney transplants. The mean age of the patients was 39.13 ± 12.56 years. There were 87.3% (n = 180) males and 12.6% (n = 26) females. The majority of transplants in our study were ABO-compatible (94.6%, n = 195) and ABO-incompatible (5.2%, n = 11). The mean age of donors was 41 ± 13.7 years. Males were 38.3% (n = 79), and females were 61.6% (n = 127). Overall survival observed in the current study was 98% (n = 202), Post-transplant, 4 patients died (n = 2 died due to COVID-19, 1 due to Heart failure and 1 was infectious mortality.) The mean cumulative dose of ATLG in the current study was 305.1 ± 61.8 mg, and the mean dose was 5.4 ± 1.4 mg/kg. The baseline etiologies of patients who underwent transplant were chronic glomerulonephritis (47.5% n = 98), diabetic nephropathy (16.9% n = 35), hypertension (29.1% n = 60), CIN, and other GMB diseases. In the current study, the figure shows overall 11.6% (n = 24) rejections and 5-year follow-up data of Serum creatinine within a normal range. Post-transplant BK Virus Nephropathy was observed in 3.39% (n = 7) cases, CMV infection in two cases, TB was observed in three cases and fungal pneumonia in one case. Conclusion Long-term 5 year follow-up of Living donor kidney transplant shows that ATLG is an effective and safe induction agent. Good compliance with Oral immunosuppressant can improve graft survival as per the current study.

Arterial hypertension in kidney transplant recipients: pathophysiology, diagnostics, treatment

Relevance: Arterial hypertension (HTN) in kidney transplant recipients is a major risk factor for cardiovascular diseases, graft rejection and premature death. In the post-transplant period in 80% of cases persistent or refractory arterial hypertension develops which is difficult to correct with conventional drug therapy. Treatment difficulties include the ineffectiveness of many first-line drugs and the fact that the most common immunosuppressive drugs (cyclosporine, tacrolimus and methylprednisolone) contribute to the development of hypertension. This type of hypertension represents a significant problem in clinical practice due to the complexity of treatment and high mortality. The need to study the treatment of post-transplant hypertension is due not only to its clinical significance, but also to the potential opportunity to improve treatment results and life expectancy of kidney transplant recipients.Objective: to study the genesis, risk factors, pathophysiology, diagnosis and treatment of posttransplant hypertension.Materials and methods: 37 literary sources were analyzed.Conclusions: High blood pressure exposes the recipient of a kidney transplant to the risk of CVD and mortality as well as increased systemic hypertension which can be a cause and a consequence of renal pathology. Hypertension is a modifiable risk factor contributing to the progression of renal failure. There is no any single treatment algorithm. It is often necessary to use several antihypertensive drugs to achieve the target blood pressure.

Demonstration of Interaction between Carbapenem Group Antibiotics and Different Immunosuppressant Drugs by Molecular Docking

Background: It has been shown that drugs used parenterally cause errors in immunosuppressant concentrations measured by LC-MS / MS method. It is yet unknown whether this measurement error is due to drug-drug interaction or analytical interference. Objective: The aim of this study is to investigate the possible interaction and inhibition concentrations of broad-spectrum antibiotics (ertapenem, meropenem, imipenem) with 4 different immunosuppressants (tacrolimus, sirolimus, everolimus, cyclosporine A) by molecular docking. Method: The docking results of ertapenem, meropenem, and imipenem-cilastatin drugs, which are frequently used in intensive care units and wards, were analyzed with the Autodock 4.2 program. Binding energy levels and inhibition concentrations were recorded. Results: The highest binding energies of the most stable conformations, providing the best compatibility among the active ingredients, belong to cilastatin. The interaction energy of cilastatin with sirolimus in 320 conformations was calculated as -4.08 kcal/mol. Sirolimus interacted with ertapenem at -3.43, imipenem at -2.53, and meropenem at -3.84 kcal/mol. According to these values, the receptor, which is the most compatible host with all ligand molecules, is sirolimus. The least interaction energy value was calculated between cyclosporine and imipenem (-1.12 kcal / mol). Conclusion: Concerning the most stable conformations of models docked with Autodock tools, it has been determined that carbapenems interact with immunosuppressants. Since the detected inhibition concentration levels can be seen in blood samples taken immediately after carbapenem injection, immunosuppressant measurement is recommended before the use of carbapenem in immunosuppressant monitoring of transplant patients.

Nonperturbative Fluorogenic Labeling of Immunophilins Enables the Wash-free Detection of Immunosuppressants.

Immunosuppressants are clinically approved drugs to treat the potential rejection of transplanted organs and require frequent monitoring due to their narrow therapeutic window. Immunophilins are small proteins that bind immunosuppressants with high affinity, yet there are no examples of fluorogenic immunophilins and their potential application as optical biosensors for immunosuppressive drugs in clinical biosamples. In the present work, we designed novel diazonium BODIPY salts for the site-specific labeling of tyrosine residues in peptides via solid-phase synthesis as well as for late-stage functionalization of whole recombinant proteins. After the optimization of a straightforward one-step labeling procedure for immunophilins PPIA and FKBP12, we demonstrated the application of a fluorogenic analogue of FKBP12 for the selective detection of the immunosuppressant drug tacrolimus, including experiments in urine samples from patients with functioning renal transplants. This chemical methodology opens new avenues to rationally design wash-free immunophilin-based biosensors for rapid therapeutic drug monitoring.