Therapeutic drug monitoring of mycophenolate mofetil in transplantation

Efficacy and Safety of Mycophenolate Mofetil In De Novo Renal Transplantation in a Retrospective Cohort of Transplant Recipients in Colombia-Esmitren Study

BACKGROUND

To describe and establish the efficacy and safety of Mycophenolate Mofetil (Micoflavin) in patients with de novo renal transplantation during one-year post-transplant follow-up. As secondary objectives, the behavior of mycophenolic acid (MPA) C0 levels in this population, the relationship between MPA levels and renal function of the grafts, the incidence of acute rejection, and the incidence of adverse effects were evaluated.

METHODS

A prospective cohort study was conducted on patients who received a first kidney transplant from a deceased donor between March 1, 2021, and February 28, 2022, at the Alma Mater of Antioquia Hospital of the Antioquia's University, in Medellín, Colombia. MPA C0 levels were taken from the patients on days 15, 30, 90, 180, and 360 after the kidney transplantation.

RESULTS

Patients presented MPA therapeutic levels in the study. The average of the MPA levels in the population was 2.5 µg/mL, with an IQR of 2.13 to 3.32. There were 5 acute rejections (27%), but none of the patients with acute rejection presented subtherapeutic levels of mycophenolate. No significant relationship was observed between mycophenolic acid levels and rejection (P = .255). The patients who completed the study had no gastrointestinal intolerance to mycophenolate, cytomegalovirus infections, or significant hematological complications.

CONCLUSIONS

MMF (Micoflavin) maintained mycophenolic acid levels C0 within the therapeutic range, was well tolerated and without the presence of significant adverse events, and maintained stable renal function throughout the follow-up period in the population studied.

Population pharmacokinetics of mycophenolic acid and dose optimisation in adult Chinese kidney transplant recipients

1. This study aimed to establish a population pharmacokinetic (PPK) model of mycophenolic acid (MPA), quantify the effect of clinical factors and pharmacogenomics of MPA, and optimise the dosage for adult kidney transplant recipients.2. One-hundred and four adult renal transplant patients were enrolled. The PPK model was established using the Phoenix® NMLE software and the stepwise methods were filtered for significant covariates. Monte Carlo simulations were performed to optimise the dosage regimen.3. A two-compartment model with first-order absorption and elimination (including lag time) provided a more accurate description of MPA pharmacokinetics. Serum albumin (ALB) significantly affected the central apparent clearance (CL/F), whereas post-transplant time and creatinine clearance were associated with a central apparent volume of distribution (V/F). The estimated population values obtained by the final model were 17.5 L/h and 93.97 L for CL/F and V/F, respectively. Simulation results revealed that larger mycophenolate mofetil doses are required as the ALB concentration decreases. This study established a PPK model of MPA and validated it using various methods. ALB significantly affected CL/F and recommended optimal dose strategies were given based on the final model. These results provide a reference for the personalised therapy of MPA for kidney transplant patients.

Pharmacokinetics and tolerability of multiple-day oral dosing of mycophenolate mofetil in healthy horses

BACKGROUND

Additional efficacious immunomodulatory treatment is needed for the management of immune-mediated disease in horses. Mycophenolate mofetil (MMF) is an immunosuppressive drug that warrants assessment as a viable therapeutic agent for horses.

HYPOTHESIS/OBJECTIVES

To evaluate the pharmacokinetics (PK) of multiple-day oral dosing of MMF in healthy horses and to determine the tolerability of this dosing regimen.

ANIMALS

Six healthy Standardbred mares.

METHODS

Horses received MMF 10 mg/kg PO q12h for 7 days in the fed state. Serial sampling was performed over 12 hours on Days 1 and 7 with trough samples collected every 24 hours, immediately before morning drug administration. Noncompartmental PK analyses were performed to determine primary PK parameters, followed by calculation of geometric means and coefficients of variation. A CBC, serum biochemical profile, physical examination, and fecal scoring were used to assess dose tolerability.

RESULTS

Seven days of treatment resulted in a mycophenolic acid (MPA) area under the curve (AUC0-12 ) of 12 594 h × ng/mL (8567-19 488 h × ng/mL) and terminal half-life (T1/2 ) of 11.3 hours (7.5-15.9 hours), yielding minor metabolite accumulation in all horses treated. Salmonellosis was detected in the feces of 2 horses by Day 7, and all horses developed myelosuppression, hyperbilirubinemia, hyporexia, decreased gastrointestinal motility, and decreased fecal output by the seventh day of treatment.

CONCLUSION AND CLINICAL IMPORTANCE

Administration of MMF at 10 mg/kg PO q12h resulted in hematologic and clinical toxicity within 1 week of treatment. A decreased MMF dose, frequency, or both is needed to avoid colic. Drug monitoring should include frequent hemograms, serum biochemical profiles, and strict biosecurity protocols.

Status and Quality of Guidelines for Therapeutic Drug Monitoring Based on AGREE II Instrument

BACKGROUND

With the progress of therapeutic drug monitoring (TDM) technology and the development of evidence-based medicine, many guidelines were developed and implemented in recent decades.

OBJECTIVE

The aim was to evaluate the current status of TDM guidelines and provide suggestions for their development and updates based on Appraisal of Guidelines for Research and Evaluation (AGREE) II.

METHODS

The TDM guidelines were systematically searched for among databases including PubMed, Embase, China National Knowledge Infrastructure, Wanfang Data, and the Chinese biomedical literature service system and the official websites of TDM-related associations. The search period was from inception to 6 April 2023. Four researchers independently screened the literature and extracted data. Any disagreement was discussed and reconciled by another researcher. The quality of guidelines was assessed using the AGREE II instrument.

RESULTS

A total of 92 guidelines were included, including 57 technical guidelines, three management guidelines, and 32 comprehensive guidelines. The number of TDM guidelines has gradually increased since 1979. The United States published the most guidelines (20 guidelines), followed by China (15 guidelines) and the United Kingdom (ten guidelines), and 23 guidelines were developed by international organizations. Most guidelines are aimed at adult patients only, while 28 guidelines include special populations. With respect to formulation methods, there are 23 evidence-based guidelines. As for quality evaluation results based on AGREE II, comprehensive guidelines scored higher (58.16%) than technical guidelines (51.36%) and administrative guidelines (50.00%).

CONCLUSION

The number of TDM guidelines, especially technical and comprehensive ones, has significantly increased in recent years. Most guidelines are confronted with the problems of unclear methodology and low quality of evidence according to AGREE II. More evidence-based research on TDM and high-quality guideline development is recommended to promote individualized therapy.

Impact of Fasting Status and Circadian Variation on the Pharmacokinetics of Mycophenolate Mofetil and the Glucuronide Metabolite in Renal Transplant Recipients

Mycophenolate mofetil (MMF) is an immunosuppressive prodrug often used to prevent allograft rejection following solid organ transplantation. After oral administration, MMF is rapidly hydrolyzed to the active metabolite mycophenolate acid (MPA), which is inactivated by glucuronosyltransferase to the mycophenolic acid glucuronide metabolite (MPAG). The aim was 2-fold: to investigate the impact of circadian variation and fasting versus nonfasting status on MPA and MPAG pharmacokinetics in renal transplant recipients (RTRs).

Methods

RTRs with stable graft function treated with tacrolimus, prednisolone, and MMF (750 mg BID) were included in this open, nonrandomized study. Two 12-h pharmacokinetic investigations were conducted in succession following morning and evening doses, both in a fasting and in a real-life nonfasting condition.

Results

A total of 30 (22 men) RTRs performed one 24-h investigation, and 16 repeated the investigation within 1 mo. In a real-life nonfasting state, MPA area under the curve (AUC)_0-12 and C ₀ failed to meet the bioequivalence criteria. Following the evening dose, mean MPA AUC_12-24 was 16% lower (P < 0.001) compared with AUC_0-12, and a shorter T _max was observed (P = 0.09). Under fasting conditions, MPA AUC_12-24 was 13% lower than AUC_0-12, and the absorption rate was slower after the evening dose (P < 0.05). MPAG displayed circadian variation only under real-life conditions with lower AUC_0-12 following the evening dose (P < 0.001).

Conclusions

Both MPA and MPAG showed circadian variation with somewhat lower systemic exposures following the evening dose with limited clinical relevance in the dosing of MMF in RTRs. Fasting status affects MMF absorption rate differently, but with similar results in systemic exposure.

The combination of exposure to Tacrolimus, mycophenolic acid, Inosine 5'-Monophosphate Dehydrogenase activity and inhibition in the first week define early histological outcomes in renal transplant recipients

Therapeutic drug monitoring is routine for Tacrolimus, while levels are not routinely monitored for mycophenolic acid (MPA). This study investigated the effect of early post-transplant pharmacokinetics (PK) of MPA and Tacrolimus along with the pharmacodynamics (PD) of MPA on biopsy-proven acute rejection (BPAR) after renal transplantation. A prospective PK/PD study with limited sampling (three blood samples) was conducted in renal transplant recipients on week 1, around Day 6 (n = 42) and at the 3rd-month biopsy on Day 90 (n = 23). The partial exposures (area under curve [AUC]_0-3.5 h ) of both MPA and Tacrolimus obtained during the first week were more predictive of rejection (combined clinical and subclinical rejection) by Day 90 than their trough concentrations or Day 90 exposures. Patients with rejection had significantly worse renal function (eGFR) and a comparatively lower exposure to MPA during the first post-transplant week. The lower MPA exposure was also associated with sub-optimal inosine monophosphate dehydrogenase (IMPDH) inhibition in patients with rejection, and the probability of rejection was higher in the presence of an increased pre-transplant IMPDH activity. A composite of parameters, including MPA exposure and IMPDH activity was found to predict acute rejection and may be beneficial along with tacrolimus monitoring early after renal transplantation.

Individualization of Mycophenolic Acid Therapy through Pharmacogenetic, Pharmacokinetic and Pharmacodynamic Testing

Mycophenolic acid (MPA) is a widely used immunosuppressive agent and exerts its effect by inhibiting inosine 5′-monophosphate dehydrogenase (IMPDH), the main regulating enzyme of purine metabolism. However, significant unexplained differences in the efficacy and tolerability of MPA therapy pose a clinical challenge. Therefore, broad pharmacogenetic, pharmacokinetic, and pharmacodynamic approaches are needed to individualize MPA therapy. In this prospective cohort study including 277 renal transplant recipients, IMPDH2 rs11706052 SNP status was assessed by genetic sequencing, and plasma MPA trough levels were determined by HPLC and IMPDH enzyme activity in peripheral blood mononuclear cells (PBMCs) by liquid chromatography–mass spectrometry. Among the 277 patients, 84 were identified with episodes of biopsy-proven rejection (BPR). No association was found between rs11706052 SNP status and graft rejection (OR 1.808, and 95% CI, 0.939 to 3.479; p = 0.076). Furthermore, there was no association between MPA plasma levels and BPR (p = 0.69). However, the patients with graft rejection had a significantly higher predose IMPDH activity in PBMCs compared to the controls without rejection at the time of biopsy (110.1 ± 50.2 vs. 95.2 ± 45.4 pmol/h; p = 0.001), and relative to the baseline IMPDH activity before transplantation (p = 0.042). Our results suggest that individualization of MPA therapy, particularly through pharmacodynamic monitoring of IMPDH activity in PBMCs, has the potential to improve the clinical outcomes of transplant patients.

Population Pharmacokinetics of Mycophenolic Acid in Renal Transplant Patients: A Comparison of the Early and Stable Posttransplant Stages

Mycophenolic acid (MPA) is an antimetabolic immunosuppressive drug widely used in solid organ transplantation and autoimmune diseases. Pharmacokinetics (PK) of MPA demonstrates high inter- and intra-variability. The aim of this study was to compare the population PK properties of MPA in adult renal transplant patients in the early and stable post-transplant stages and to simulate an optimal dosing regimen for patients at different stages. A total of 51 patients in the early post-transplant period (1 week after surgery) and 48 patients in the stable state (5.5–10 years after surgery) were included in the study. In the two-compartment population PK model, CL/F (23.36 L/h vs. 10.25 L/h) and V/F (78.07 vs. 16.24 L) were significantly different between the two stages. The dose-adjusted area under the concentration time curve (AUC_ss,12h/dose) for patients in the early stage were significantly lower than those for patients in the stable state (40.83 ± 22.26 mg h/L vs. 77.86 ± 21.34 mg h/L; p < 0.001). According to Monte Carlo simulations, patients with 1.0–1.5 g of mycophenolate mofetil twice daily in the early phase and 0.50–0.75 g twice daily in the stable phase had a high probability of achieving an AUC_ss,12h of 30–60 mg h/L. In addition, limited sampling strategies showed that two 4-point models (C0-C1-C2-C4 and C1-C2-C3-C6) performed well in predicting MPA exposure by both Bayesian estimate and regression equation and could be applied in clinical practice to assist therapeutic drug monitoring of MPA.

Two-Year Outcomes of Low-Exposure Extended-Release Tacrolimus and Mycophenolate Mofetil Regimen in De Novo Kidney Transplantation: A Multi-center Randomized Controlled Trial

BACKGROUND

Once-daily extended-release tacrolimus (TACER) is commonly administered following kidney transplantation (KTx); however, its optimal dosage remains unknown.

METHODS

In this multi-center, randomized controlled trial, 62 living donor KTx recipients were assigned to either standard-exposure (SE; n = 32) or low-exposure (LE; n = 30) TACER (Graceptor®, Astellas Pharm Inc.) groups. All patients received basiliximab and mycophenolate mofetil (MMF). The primary outcomes were acute rejection, graft/patient survival, and the secondary outcomes were incidence of cytomegalovirus infection, and de novo donor-specific antibodies (dnDSA) production.

RESULTS

The tacrolimus trough level and estimated area under the blood concentration-time curve (eAUC) were significantly higher in SE than in LE (SE vs LE; one year: 5.0 ± 0.9 ng/mL and 206.9 ± 26.8 ngཥh/mL vs 3.4 ± 1.0 ng/mL and 153.9 ± 26.4 ngཥh/mL; two years: 4.8 ± 1.0 ng/mL and 204.9 ± 30.1 ngཥh/mL vs 3.8 ± 0.9 ng/mL and 164.4 ± 27.0 ngཥh/mL). In contrast, the dosage and eAUC of MMF did not differ between groups. Two-year graft and patient survival rates were 100% in both groups, and acute rejection rates were 0% and 10% in the SE and LE, respectively (p = 0.11). The mean estimated glomerular filtration rates did not differ between the groups. Cytomegalovirus infection was slightly lower in the LE (SE: 12.5% and LE: 6.7%, p = 0.37). In the LE, four cases of dnDSA were noted within two years of transplantation; no case was observed in the SE (p = 0.034).

CONCLUSIONS

Although the LE TACER regimen showed similar rates of acute rejection, as well as graft and patient survival compared with SE after KTx, LE was significantly more associated with dnDSA. Further investigation of its long-term effect on graft survival is warranted. (University Hospital Medical Information Network Clinical Trials Registry ID: UMIN000033089). This article is protected by copyright. All rights reserved.

Is the failure of recent trials on withdrawal of calcineurin inhibitors due to inadequate mycophenolic acid dosing?

Calcineurin inhibitors (CNIs) are the mainstay immunosuppressive therapy after kidney transplantation, despite their side effects. Recently, several randomized controlled trials attempting CNI withdrawal or minimization in stable, low-risk kidney transplant recipients led to an unacceptable risk of acute rejection and de novo HLA antibody formation. In the opinions of many, these trials definitively demonstrated that CNI-free regimens in the context of mycophenolate mofetil (MMF) maintenance are too risky. It can be argued, however, that the investigators failed to optimize the dose of the remaining immunosuppressive therapy. In particular, the potential benefit of MMF dosing based on the targeted mycophenolic acid (MPA) concentration was not taken into account. In this review, we present an overview of the studies on CNI withdrawal, both recent and older, paying specific attention to the MMF dose and elaborating on the possible benefit of MPA monitoring in this setting.

No Influence of Everolimus on Mycophenolic Acid Area Under the Concentration-Time Curve: Limited Sampling Strategy for Mycophenolic Acid in Japanese Kidney Transplant Recipients Treated With Tacrolimus, Mycophenolate Mofetil, Steroid, and Everolimus

BACKGROUND

Despite a growing need for everolimus (EVR) to reduce calcineurin inhibitor toxicity in kidney transplantation (KTx), the influence of EVR on the pharmacokinetics of mycophenolic acid (MPA), a mycophenolate mofetil (MMF) active metabolite, is obscure, and no suitable limited sampling strategy (LSS) for MPA when EVR is concomitantly present exists. We aimed to investigate the influence of EVR on MPA pharmacokinetics in KTx.

MATERIALS AND METHODS

This study complied with all principles of the Declaration of Helsinki. Twenty patients were initially administered tacrolimus, MMF, and methylprednisolone and then received EVR 4 months after KTx. Approximately 4 weeks before and after EVR administration, the estimated value of the area under the concentration-time curve for MPA from 0 to 12 hours (MPA-AUC0-12) was calculated using MPA blood concentration just before and 1, 2, 4, and 6 hours after MMF administration. We compared several MPA pharmacokinetics parameters before and after EVR addition and determined the best estimation equation for LSS of MPA-AUC0-12.

RESULTS

Although MPA-C6 per dose (MPA-C6/D) significantly decreased after EVR addition (from 3.4 [±2.2] ng/mL/g to 2.5 [±0.9] ng/mL/g), MPA-C0/D, -C1/D, -C2/D, -C4/D, and MPA-AUC0-12/D showed no significant change. MPA-AUC0-12/D did not correlate with EVR-AUC0-12/D. The best estimation equation for LSS of MPA-AUC0-12 by 2 time points was [(2.94 × C2) + (5.09 × C4) + 5.32] (R² = 0.73) and [(5.70 × C0) + (1.39 × C1) + 22.45] (R² = 0.72) before and after EVR addition, respectively.

CONCLUSIONS

EVR can be safely combined with MMF after KTx once our results have been reevaluated.

Effect of mycophenolic acid and tacrolimus on the incidence of infectious complications after kidney transplantation

INTRODUCTION

Infectious complications remain a common cause of mortality after kidney transplantation (KTx). Goal of effective immunosuppressive treatment (IS) must be balanced between decreasing incidence of acute kidney rejection (AKR) and avoiding the incidence of infections, at the same time.

MATERIALS AND METHODS

The aim of our analysis was to identify the risk of fixed daily dose (DD) of mycophenolic acid (MPA) and levels of tacrolimus (TAC) in the development of a single, recurrent infection and AKR after KTx.

RESULTS

Our analysis consisted of 100 patients after KTx (66 males, 34 females). MPA DD > 1080 mg was a risk factor (RF) for recurrent infection in general (OR 1.2964;P = 0.0277), for recurrent bacterial infection from 1^st to 6^th month (OR 1.2674;P = 0.0151), recurrent bacterial infection (OR 1.2574;P = 0.0436), single viral infection (OR 1.2640;P = 0.0398) from 6^th-12^th month after KTx. MPA DD > 1080 mg and levels of TAC above recommended levels were not independent RF for the incidence of the infection.

CONCLUSION

MPA DD > 1080 mg as a RF for recurrent infection starting in the 1^st month after KTx with significant association between the incidence of infections and MPA DD and TAC levels, without increased risk of AKR. In the centers with fixed dosing of IS, this can lead to lowering the risk of infections by decreasing MPA DD 1 month after KTx without increasing risk of infections.

Association of ABCC2 Haplotypes to Mycophenolic Acid Pharmacokinetics in Stable Kidney Transplant Recipients

Mycophenolic acid exhibits significant interpatient pharmacokinetic variability attributed to factors including race, sex, concurrent medications, and enterohepatic circulation of the mycophenolic acid glucuronide metabolite to mycophenolic acid. This conversion by enterohepatic circulation is mediated by the multidrug resistance-associated protein 2, encoded by ABCC2. This study investigated ABCC2 haplotype associations with mycophenolic acid pharmacokinetics in 147 stable kidney transplant recipients receiving mycophenolic acid in combination with calcineurin inhibitors. The role of the ABCC2 genotypes -24C>T (rs717620), 1249C>T (rs2273697), and 3972C>T (rs3740066) were evaluated in prospective, cross-sectional pharmacokinetic studies of stable recipients receiving mycophenolic acid and either tacrolimus or cyclosporine. Haplotype phenotypic associations with mycophenolic acid pharmacokinetic parameters were computed using THESIAS (v. 3.1). Four ABCC2 haplotypes with estimated frequencies greater than 10% were identified (H1:CGC [wild type], H9:CGT, H2:CAC, H12:TGT). There were no differences in haplotype frequencies by either race or sex. There were significant associations of pharmacokinetic parameters with ABCC2 haplotypes for mycophenolic acid clearance (L/h), mycophenolic acid AUC_0-12h (mg·h/L), and the ratio of mycophenolic acid glucuronide to mycophenolic acid AUC_0-12h . The wild-type haplotype ABCC2 CGC had greater mycophenolic acid AUC_0-12h (P = .017), slower clearance (P = .013), and lower mycophenolic acid glucuronide to mycophenolic acid AUC_0-12h ratio (P = .047) compared with the reduced function ABCC2 haplotype CGT. These differences were most pronounced among patients receiving tacrolimus cotreatment. No phenotypic associations were found with the cyclosporine-mycophenolic acid regimen. Variation in ABCC2 haplotypes contributes to subtherapeutic mycophenolic acid exposure and influences interpatient variability in pharmacokinetic phenotypes based on concurrent calcineurin inhibitor treatment.

Towards therapeutic drug monitoring of mycophenolic acid in mucous membrane pemphigoid: A retrospective single-centre study

BACKGROUND

Mycophenolate mofetil (MMF) is theoretically a treatment of choice for mucous membrane pemphigoid (MMP), due to its good long-term tolerance and efficacy especially in elderly patients. However, no therapeutic monitoring is currently performed despite its large inter-individual variability.

OBJECTIVES

The aim of this study was to investigate the exposure/effect relationship based on the area under the curve (AUC) or trough level of mycophenolic acid in MMP patients.

METHODS

Thirteen patients (n = 29 AUC measurements performed between February 2013 and November 2016) treated for MMP at Limoges University Hospital were evaluated using the Mucous Membrane Pemphigoid Disease Area Index score, and patients were classified as improvement (>50% decrease vs. baseline) vs. stabilisation (<50%) or non-response (no improvement). AUC was estimated using a population pharmacokinetic model and Bayesian estimation. The association between exposure parameters, demographic variables and response group was investigated using time-dependent Cox models, and an AUC threshold for 'improvement' was also investigated.

RESULTS

An improvement was observed in approximately 70% of the patients. Only the MPA AUC_0-24 h was retained in the multivariate analysis with a decreased risk of stabilisation/non-response per 10 mg*h/L increase, (HR = 0.64, 95% CI = [0.43-0.94], P = 0.0038). That led to an AUC_0-24 h threshold of 89 mg*h/L associated with excellent performances (AUC ROC = 0.828, Sen = 75%, Spe = 100%, P = 0.0001).

DISCUSSION/CONCLUSION

An association between MPA exposure and disease was observed. Therapeutic drug monitoring can be proposed with an AUC_0-24 h threshold of 89 mg*h/L. It might improve the long-term response of patients to this drug with better tolerance than rituximab or cyclophosphamide.

Mycophenolic acid drug monitoring in patients with systemic sclerosis associated with diffuse skin and/or pulmonary involvement: A monocentric and retrospective French study

OBJECTIVE

To explore pharmacokinetic/pharmacodynamic relationship between mycophenolic acid area under the curve and clinical response at 1 year on skin involvement or interstitial lung disease in patients with systemic sclerosis.

METHOD

Retrospective, monocentric study based on French Scleroderma Database in patients receiving mycophenolate mofetil who experienced a limited sampling strategy to estimate individual mycophenolic acid area under the curve plus two pulmonary function tests and skin evaluation after 1 month and 1 year. Efficacy criterions were variations of modified Rodnan skin score, forced vital capacity, and diffusing lung capacity for carbon monoxide at 1 year.

RESULTS

We included 52 patients; mean age was 49 years (range 17-79), and 36 (69%) were females. Fifty patients (96%) had skin sclerosis, 39 (75%) had diffuse skin involvement with a median modified Rodnan skin score of 14 (0-38). Thirty-eight (76%) had interstitial lung disease, with median forced vital capacity and diffusing lung capacity for carbon monoxide of 81% (37-127) and 56% (28-103) from predicted values, respectively. Twenty-five (51%) patients had pulmonary fibrosis. Mycophenolate mofetil was given for 10 months (0-173) at a median dose of 2000 mg/day (500-3000). In the entire population, no relationship was found between area under the curve and modified Rodnan skin score (p = 0.085), forced vital capacity (p = 0.80), or diffusing lung capacity for carbon monoxide (p = 0.72) variations at 1 year.

CONCLUSION

In this retrospective study, we failed to document any relationship between mycophenolic acid area under the curve and skin involvement or interstitial lung disease evolution. Routine monitoring of mycophenolic acid in systemic sclerosis patients treated with mycophenolate mofetil cannot be recommended based on our results.

Pharmacokinetics of mycophenolic acid after haplo-hematopoietic stem cell transplantation in Japanese recipients

PURPOSE

Mycophenolate mofetil (MMF), a mycophenolic acid (MPA) prodrug, is used to prevent graft-versus-host disease (GVHD) in hematopoietic stem cell transplantation (HSCT). Although previous studies have reported that enterohepatic circulation (EHC) of MPA, which is usually observed in MMF-treated patients, does not occur in HSCT patients, it is unclear what happens in haploidentical-HSCT (haplo-HSCT) patients, who are using post-transplant cyclophosphamide. This study was conducted to investigate MPA pharmacokinetics in haplo-HSCT patients.

METHODS

Seventeen haplo-HSCT patients, who received MMF for GVHD prophylaxis, were enrolled in this study. We collected blood samples on days 14 and 28, and plasma MPA concentrations were measured by high-performance liquid chromatography; pharmacokinetic parameters such as area under the curve (AUC), mean residence time (MRT), and apparent oral clearance (CL/F) were measured with moment analysis. We also evaluated EHC as AUC_6-12h/AUC_0-12h.

RESULTS

There was no significant difference in MPA pharmacokinetic parameters between days 14 and 28. There was also no difference between the pharmacokinetic parameter changes and diarrhea. Additionally, varying plasma MPA concentrations suggested that MPA EHC did not occur.

CONCLUSION

In this study, we revealed the pharmacokinetics of MMF in Japanese haplo-HSCT recipients. Additionally, our study demonstrated that MPA EHC might not occur in Japanese haplo-HSCT recipients.

PK/PD Study of Mycophenolate Mofetil in Children With Systemic Lupus Erythematosus to Inform Model-Based Precision Dosing

Objectives: To evaluate the mycophenolic acid [MPA, the active form of mycophenolate mofetil (MMF)] pharmacokinetic parameters in relation to clinical response to identify target exposure ranges in pediatric patients with systemic lupus erythematosus (SLE).

Methods: This was a retrospective study using pharmacokinetic data collected in 67 pediatric patients aged 4–18 years with SLE. Target MPA exposures for effective inhibition of SLE activity (as measured by SLE disease Activity Index (SLEDAI), active SLE was defined as a SLEDAI score of ≥6, and a controlled disease was defined as a SLEDAI score of ≤4) were assessed by receiver operating characteristic (ROC) curve and logistic regression. Exposure-response models were developed to quantitatively describe the relationship between SLEDAI score and AUC_0–12 or C_trough, respectively.

Results: The MPA AUC_0-12 in patients with active SLE was significantly lower than that in patients with inactive SLE. ROC analysis revealed that an AUC_0–12 threshold of 39 μg h/ml or a C_trough of 1.01 μg/ml was associated with the lowest risk of active SLE. Logistic regression analysis revealed that an AUC_0–12 of less than 34 μg h/ml or a C_trough of less than 1.2 μg/ml probably is associated with active SLE. The results of the exposure-response modeling also indicated that an AUC_0-12 less than 32 μg h/ml or a C_trough less than 1.1 μg/ml was associated with suboptimal clinical outcome. An AUC_0-12 above 50 μg h/ml or a C_trough above 1.7 ug/ml was associated with disease control.

Conclusion: Both AUC_0–12 and C_trough of MPA are predictive of the likelihood of active SLE in pediatric patients receiving MMF. An individualized dosing regimen of MMF, with a target AUC_0–12 or C_trough, should be considered for SLE patients.

Pharmacokinetics of Enteric-Coated Mycophenolate Sodium Metabolites in Patients Over 60 Years Old Within the First Year After Renal Transplantation

OBJECTIVE

It is still unclear whether mycophenolic acid (MPA) doses should be adjusted for older patients. Therefore, we compared the pharmacokinetics of MPA, mycophenolic acid glucuronide (MPAG), and free MPA (fMPA) between older and younger renal transplant recipients.

METHODS

We included 12 patients <60 years and 6 patients >60 years within the first year after renal transplantation, who were receiving enteric-coated mycophenolate sodium, tacrolimus, and steroids. Blood samples were collected up to 12 hours after drug administration.

RESULTS

MPA and fMPA pharmacokinetics were similar for patients <60 and >60 years; however, the MPA area under the concentration-time curve from 0 to 12 hours (AUC_0-12) was 1.2-fold lower in the older patients. MPAG pharmacokinetics were more than 1.5-fold higher in patients >60 years, which might be related to deteriorated renal function in older people. Moreover, the mean (MPAG AUC_0-12)/(MPA AUC_0-12) ratio was more than 2-fold higher in patients >60 years. The second maximal MPA concentration was more frequently observed in patients <60 years, although all patients received tacrolimus. The percentage of patients with MPA concentration before the next drug dose (C_trough) and AUC_0-12 within and below target was the same in both groups. All patients >60 years had MPA AUC_0-12 >30 μg·h/mL within 22 to 114 days after transplantation.

CONCLUSIONS

MPA therapeutic monitoring should be recommended in enteric-coated mycophenolate sodium--treated patients >60 years because MPA AUC_0-12 exceeded the recommended value in half of the studied patients.

Effect of the proton-pump Inhibitor pantoprazole on MycoPhenolic ACid exposure in kidney and liver transplant recipienTs (IMPACT study): a randomized trial

BACKGROUND

Mycophenolic acid (MPA) is widely utilized as an immunosuppressant in kidney and liver transplantation, with reports suggesting an independent relationship between MPA concentrations and adverse allograft outcome. Proton-pump inhibitors (PPIs) may have variable effects on the absorption of different MPA formulations leading to differences in MPA exposure.

METHODS

A multicentre, randomized, prospective, double-blind placebo-controlled cross-over study was conducted to determine the effect of the PPI pantoprazole on the MPA and its metabolite MPA-glucuronide (MPA-G) area under the curve (AUC) >12 h (MPA-AUC12 h) in recipients maintained on mycophenolate mofetil (MMF) or enteric-coated mycophenolate sodium (EC-MPS). We planned a priori to examine separately recipients maintained on MMF and EC-MPS for each pharmacokinetic parameter. The trial (and protocol) was registered with the Australian New Zealand Clinical Trials Registry on 24 March 2011, with the registration number of ACTRN12611000316909 ('IMPACT' study).

RESULTS

Of the 45 recipients screened, 40 (19 MMF and 21 EC-MPS) were randomized. The mean (standard deviation) recipient age was 58 (11) years with a median (interquartile range) time post-transplant of 43 (20-132) months. For recipients on MMF, there was a significant reduction in the MPA-AUC12 h [geometric mean (95% confidence interval) placebo: 53.9 (44.0-65.9) mg*h/L versus pantoprazole: 43.8 (35.6-53.4) mg*h/L; P = 0.004] when pantoprazole was co-administered compared with placebo. In contrast, co-administration with pantoprazole significantly increased MPA-AUC12 h [placebo: 36.1 (26.5-49.2) mg*h/L versus pantoprazole: 45.9 (35.5-59.3) mg*h/L; P = 0.023] in those receiving EC-MPS. Pantoprazole had no effect on the pharmacokinetic profiles of MPA-G for either group.

CONCLUSIONS

The co-administration of pantoprazole substantially reduced the bioavailability of MPA in patients maintained on MMF and had the opposite effect in patients maintained on EC-MPS, and therefore, clinicians should be cognizant of this drug interaction when prescribing the different MPA formulations.

Quantification of mycophenolic acid in human plasma by liquid chromatography with time-of-flight mass spectrometry for therapeutic drug monitoring

This study presents, for the first time, the development and validation of a liquid chromatography and time-of-flight mass-spectrometry (LC-TOF-MS) based assay to quantify mycophenolic acid (MPA) in patient samples as part of a routine therapeutic drug monitoring service. MPA was extracted from 50 μl human plasma by protein precipitation, using sulindac as internal standard (IS). Separation was obtained on a Luna™ Omega polar C₁₈ column kept at 40°C. The mobile phase consisted of a mixture of acetonitrile-deionized water (50:50, v/v) with 0.1% formic acid at a flow rate of 350 μl/min. Analyte and IS were monitored on a TOF-MS using a Jet-Stream™ (electrospray) interface running in positive mode. Assay performance was evaluated by analysing patient plasma (N = 69) and external quality assessment (N = 6) samples. The retention times were 2.66 and 2.18 min for MPA and IS, respectively. The lower limit of quantification of MPA was 0.1 μg/ml. The within- and between-assay reproducibility results ranged from 1.81 to 10.72%. Patient and external quality assessment sample results were comparable with those obtained previously by an in-house validated LC-MS/MS method. This method showed satisfactory analytical performance for the determination of MPA in plasma over the calibration range of 0.1-15.0 μg/ml.

Mycophenolate mofetil for systemic sclerosis: drug exposure exhibits considerable inter-individual variation-a prospective, observational study

Objective

Mycophenolate mofetil (MMF) is an established therapy for systemic sclerosis (SSc), but its pharmacokinetics in this disease remains unexplored. We have investigated drug exposure in MMF-treated patients with SSc in relation to clinical features of the disease and common concomitant drugs.

Methods

This study was predefined to include 35 MMF-treated SSc patients who were using MMF at a fixed dose of 0.5, 1.0 or 1.5 g twice daily since at least 3 months. The 12-h drug exposure of the active MMF metabolite mycophenolic acid (MPA) was estimated by repeated analysis of plasma MPA over a 6-h period. This 12-h drug exposure was dose normalised to a daily intake of 3 g MMF (MPA_AUC_3g) in order to compare subjects using MMF at different doses. Drug exposure was analysed in reference to the clinical characteristics including body weight, renal function, autoantibodies, intestinal dysbiosis, intestinal inflammation assessed by faecal (F)-calprotectin, intestinal symptoms assessed by the University of California Los Angeles Scleroderma Trial Consortium Gastrointestinal Tract Instrument 2.0 and concomitant drug usage including proton-pump inhibitors (PPI).

Results

Thirty-four out of 35 study participants completed the study. The mean daily MMF dose was 2.1 g. Drug exposure expressed as MPA_AUC_3g varied up to 8-fold between patients (median 115, range 27–226 mg h/L).

MPA_AUC_3g was inversely related to body weight (r_s = − 0.58, p < 0.001) and renal function (r_s = − 0.34, p = 0.054). Anti-topoisomerase-1 antibodies and male sex were associated with lower MPA_AUC_3g (87 vs 123 and 71 vs 141; p = 0.008 and p = 0.015, respectively). MPA_AUC_3g was inversely related to the intestinal abundance of lactobacilli and to F-calprotectin (r_s = − 0.54, p = 0.004; r_s = − 0.36, p = 0.034), but not to gastrointestinal symptoms. MPA_AUC_3g was inversely related to PPI usage (r_s = − 0.45, p = 0.007). We found no association between MPA_AUC_3g and disease subtype, disease duration or disease activity.

Conclusion

MMF-treated SSc patients exhibit considerable inter-individual variation in drug exposure, and lower MPA levels were primarily found in PPI users with poor prognostic factors. Body weight, renal function, sex, serology, gastrointestinal manifestations and/or measuring individual MPA exposure should be considered when using MMF for SSc.

Lack of concordance between EMIT assay and LC-MS/MS for Therapeutic Drug Monitoring of Mycophenolic Acid: Potential increased risk for graft rejection?

Therapeutic drug monitoring (TDM) of immunosuppressive drugs is crucial in organ-transplanted patients to prevent rejection or toxic effects due to inadequate dosage. Mycophenolic acid (MPA) is a commonly used immunosuppressant in this setting. Nowadays, MPA concentrations are monitored by Enzyme Multiplied Immunoassay Technology (EMIT), and Liquid Chromatography (LC)-based techniques, particularly coupled to Tandem Mass Spectrometry (LC-MS/MS). This study evaluates the concordance between TDM results for MPA obtained through CE-IVD EMIT and LC-MS/MS assays in plasma samples. LC-MS/MS quantification was based on a commercial kit and the analytical performance in terms of accuracy was tested through external proficiency tests and inter-laboratory comparison with a home-made HPLC-UV method. Both these evaluations confirmed the reliability of the LC-MS/MS method (1.6 % and 9.0 % of bias, respectively). Conversely, the comparison between EMIT and LC-MS/MS showed overestimation by EMIT of 33.5 %. This bias resulted concentration-dependent, ranging from 46.4 % in the concentration range of 1-2 mg/L, to 21.4 % over 4 mg/L. Considering the theoretical clinical impact of this overestimation, a fraction comprised between 12.4 % and 31.4 % of samples which resulted over three different minimum effective concentration values by EMIT (no indication for dose adjustment) had discordant indications by LC-MS/MS (dose adjustment needed). Concluding, this study highlights a clinically relevant systematic overestimation of MPA concentration by EMIT, supporting the switch to LC-MS/MS techniques for TDM purpose. However, further prospective studies are needed in order to evaluate the clinical impact of switching the TDM activity from EMIT to LC-MS/MS in a larger cohort in a long period.

Population pharmacokinetics of mycophenolic acid in Mexican patients with lupus nephritis

Background

Mycophenolic acid (MPA) is an effective oral immunosuppressive drug used to treat lupus nephritis (LN), which exhibits large pharmacokinetic variability. This study aimed to characterize MPA pharmacokinetic behaviour in Mexican LN patients and to develop a population pharmacokinetic model which identified factors that influence MPA pharmacokinetic variability.

Methods

Blood samples from LN patients treated with mycophenolate mofetil (MMF) were collected pre dose and up to six hours post dose. MPA concentrations were determined by a validated ultra-performance liquid chromatography tandem mass spectrometry technique. Patients were genotyped for polymorphisms in enzymes (UGT1A8, 1A9 and 2B7) and transporters (ABCC2 and SLCO1B3). The anthropometric, clinical, genetic and co-medication characteristics of each patient were considered as potential covariates to explain the variability.

Results

A total of 294 MPA concentrations from 40 LN patients were included in the development of the model. The data were analysed using NONMEM software and were best described by a two-compartment linear model. MPA CL, Vc, Vp, Ka and Q were 15.4 L/h, 22.86 L, 768 L, 1.28 h−1and 20.3 L/h, respectively. Creatinine clearance and prednisone co-administration proved to have influence on clearance, while body weight influenced Vc. The model was internally validated, proving to be stable. MMF dosing guidelines were obtained through stochastic simulations performed with the final model.

Conclusions

This is the first MPA population pharmacokinetic model to have found that co-administration of prednisone results in a considerable increase on clearance. Therefore, this and the other covariates should be taken into account when prescribing MMF in order to optimize the immunosuppressant therapy in patients with LN.

A new model to determine Optimal Exposure to Tacrolimus and Mycophenolate Mofetil after renal transplantation

BACKGROUND

Drug dosing for Tacrolimus (TAC) and Mycophenolate Mofetil (MMF) after kidney transplantation remains challenging. Therapeutic drug monitoring (TDM) offers a means to individualize drug dosing and improve outcomes.

METHODS

In this observational study, patients having mycophenolic acid (MPA) exposure assessed by limited sampling strategy (LSS) within the first 6 months were included and followed for 1 year.

RESULTS

A total of 113 clinical events occurring in 110 patients were classified into 3 groups: Group 1 Stable (n = 34), Group 2 Over drug exposed (n = 64) having infections or drug toxicity and Group 3 Under drug exposed (n = 15) developing rejection or de novo donor-specific alloantibodies. Although TAC levels, MMF dose, MPA, and MPA Glucuronide (MPAG) exposure, expressed as area under curve (AUC), individually failed to predict outcomes, a scoring model incorporating all 3 drug levels TAC TDM × (MPA AUC + MPAG/10 AUC) correctly classified outcomes. A score over 1071 had a sensitivity and specificity of 0.94 (95% CI 0.56-0.83) and 0.84 (95% CI 0.69-0.89) for over exposure. A score below 625 had a sensitivity and specificity of 0.76 (95% CI 0.53-0.93) and 0.80 (95% CI 0.41-0.70) for under exposure.

CONCLUSIONS

This integrated model of assessing TAC and MMF exposure may facilitate individualized therapy.

Effect of Protein Binding on Exposure of Unbound and Total Mycophenolic Acid: A Population Pharmacokinetic Analysis in Chinese Adult Kidney Transplant Recipients

OBJECTIVES

The population pharmacokinetic (popPK) characteristics of total mycophenolic acid (tMPA) have been investigated in various ethnic populations. However, investigations of popPK of unbound MPA (uMPA) are few. Thus, a popPK analysis was performed to: (1) characterize the PK of uMPA and tMPA and its 7-O-mycophenolic acid glucuronide (MPAG) metabolite in kidney transplant patients cotreated with cyclosporine (CsA), and (2) identify the clinically significant covariates that explain variability in the dose-exposure relationship.

METHODS

A total of 740 uMPA, 741 tMPA, and 734 total MPAG (tMPAG) concentration-time data from 58 Chinese kidney transplant patients receiving MPA in combination with CsA were analyzed using NONMEM® software with the stochastic approximation expectation maximization (SAEM) followed by the important sampling (IMP) method. The influence of covariates was tested using a stepwise procedure.

RESULTS

The PK of uMPA and unbound MPAG (uMPAG) were characterized by a two- and one-compartment model with first-order elimination, respectively. A linear protein binding model was used to link uMPA and tMPA. Apparent clearance (CL/F) and central volume of distribution (VC/F) of uMPA (CLuMPA/F and VCuMPA/F, respectively) and protein binding rate constant (k B) were estimated to be 851 L/h [relative standard error (RSE), 7.1%], 718 L (18.5%) and 53.4/h (2.3%), respectively. For uMPAG, the population values (RSE) of CL/F (CLuMPAG) and VC/F (VCuMPAG/F) were 5.71 L/h (4.4%) and 29.9 L (7.7%), respectively. Between-subject variability (BSVs) on CLuMPA/F, VCuMPA/F, CLuMPAG/F, and VCuMPAG/F were 51.0, 80.0, 31.8 and 48.4%, respectively, whereas residual unexplained variability (RUVs) for uMPA, tMPA, and uMPAG were 47.0, 45.9, and 22.0%, respectively. Significant relationships were found between k B and serum albumin (ALB) and between CLuMPAG/F and glomerular filtration rate (GFR). Additionally, model-based simulation showed that changes in ALB concentrations substantially affected tMPA but not uMPA exposure.

CONCLUSIONS

The established model adequately described the popPK characteristics of the uMPA, tMPA, and MPAG. The estimated CLuMPA/F and unbound fraction of MPA (FUMPA) in Chinese kidney transplant recipients cotreated with CsA were comparable to those published previously in Caucasians. We recommend monitoring uMPA instead of tMPA to optimize mycophenolate mofetil (MMF) dosing for patients with lower ALB levels.

The utility of trough mycophenolic acid levels for the management of lupus nephritis

Background

Monitoring of mycophenolic acid (MPA) levels may be useful for effective mycophenolate mofetil (MMF) dosing. However, whether commonly obtained trough levels are an acceptable method of surveillance remains debatable. We hypothesized that trough levels of MPA would be a poor predictor of area under the curve (AUC) for MPA.

Methods

A total of 51 patients with lupus nephritis who were on MMF 1500 mg twice a day and had a 4-h AUC done were included in this study. MPA levels were measured prior to (C0) and at 1 (C1), 2 (C2) and 4 (C4) h, followed by 1500 mg of MMF. The MPA AUC values were calculated using the linear trapezoidal rule. Regression analysis was used to examine the relationship between the MPA trough and AUC. Differences in the MPA trough and AUC between different clinical and demographic categories were compared using t-tests.

Results

When grouped by tertiles there was significant overlap in MPA, AUC 0-4 and MPA trough in all tertiles. Although there was a statistically significant correlation between MPA trough levels and AUC, this association was weak and accounted for only 30% of the variability in MPA trough levels. This relationship might be even more unreliable in men than women. The use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers was associated with increased MPA trough levels and AUC at 0-4 h (AUC0-4).

Conclusion

Trough levels of MPA do not show a strong correlation with AUC. In clinical situations where MPA levels are essential to guide therapy, an AUC0-4 would be a better indicator of the adequacy of treatment.

Influence of Calcineurin Inhibitor and Sex on Mycophenolic Acid Pharmacokinetics and Adverse Effects Post-Renal Transplant

Tacrolimus or cyclosporine is prescribed with mycophenolic acid posttransplant and contributes to interpatient variability in mycophenolic acid pharmacokinetics and response. Cyclosporine inhibits enterohepatic circulation of the metabolite mycophenolic acid glucuronide, which is not described with tacrolimus. This study investigated mycophenolic acid pharmacokinetics and adverse effects in stable renal transplant recipients and the association with calcineurin inhibitors, sex, and race. Mycophenolic acid and mycophenolic acid glucuronide area under the concentration-time curve from 0 to 12 hours (AUC0-12h ) and apparent clearance were determined at steady state in 80 patients receiving cyclosporine with mycophenolate mofetil and 67 patients receiving tacrolimus with mycophenolate sodium. Gastrointestinal adverse effects and hematologic parameters were evaluated. Statistical models evaluated mycophenolic acid pharmacokinetics and adverse effects. Mycophenolic acid AUC0-12h was 1.70-fold greater with tacrolimus (68.9 ± 30.9 mg·h/L) relative to cyclosporine (40.8 ± 17.6 mg·h/L); P < .001. Target mycophenolic acid AUC0-12h of 30-60 mg·h/L was achieved in 56.3% on cyclosporine compared with 34.3% receiving tacrolimus (P < .001). Mycophenolic acid clearance was 48% slower with tacrolimus (10.6 ± 4.7 L/h) relative to cyclosporine (20.5 ± 10.0 L/h); P < .001. Enterohepatic circulation occurred less frequently with cyclosporine (45%) compared with tacrolimus (78%); P < 0.001; with a 2.9-fold greater mycophenolic acid glucuronide AUC0-12h to mycophenolic acid AUC0-12h ratio (P < .001). Race did not affect mycophenolic acid pharmacokinetics. Gastrointestinal adverse effect scores were 2.2-fold higher with tacrolimus (P < .001) and more prominent in women (P = .017). Lymphopenia was more prevalent with tacrolimus (52.2%) than cyclosporine (22.5%); P < 0.001. Calcineurin inhibitors and sex contributed to interpatient variability in mycophenolic acid pharmacokinetics and adverse effects post-renal transplant, which could be attributed to differences in enterohepatic circulation.

Generics in transplantation medicine: Randomized comparison of innovator and substitution products containing mycophenolate mofetil

Objective: Mycophenolate mofetil (MMF) is widely used as an immunosuppressant for the prophylaxis of acute organ rejection in recipients of solid organ transplants. Materials and methods: We have compared, in healthy subjects, the pharmacokinetics of mycophenolic acid when MMF was administered in the form of the innovator product CellCept (F. Hoffmann-La Roche Ltd.) or one of three commercially available generics, Renodapt (Biocon Ltd.), Mycept (Panacea Biotec), or Cellmune (Cipla Ltd.). The study was powered to detect a 20% difference in mean formulation performance measures, but not to formally evaluate bioequivalence. Geometric mean ratios of maximum concentrations (C_max) and areas under plasma concentration-time curves were calculated. Results: Comparing generics against each other, the differences in point estimates of the geometric mean ratios of C_max of two of the comparisons were either borderline within (Renodapt/Cellmune) or clearly outside (Mycept/Cellmune) a region of 80 – 125% around the reference mean, indicating that bioequivalence between these generics may be difficult to show. Conclusion: Physicians in the field of transplantation should be aware of the potential risk of altering the therapeutic outcome when switching from one preparation of MMF to another. ClinicalTrials.gov identifier: NCT02981290.

Macrophage lipid accumulation in the presence of immunosuppressive drugs mycophenolate mofetil and cyclosporin A

OBJECTIVE

Mycophenolate (MPA) and cyclosporin A (CsA) are two immunosuppressive agents currently used for the treatment of autoimmune diseases. However, reports regarding their effects on inflammation and lipid handling are controversial. Here, we compare the effect of these two drugs on the expression of proteins involved in cholesterol handling and lipid accumulation in a macrophage cell system utilizing M0, M1 and M2 human macrophages and in murine bone marrow-derived macrophages (BMDM).

METHODS

Differentiated M0, M1 and M2 subsets of THP-1 human macrophages were subjected to various concentrations of either MPA or CsA. Expression of proteins involved in reverse cholesterol transport (ABCA1 and 27-hydroxylase) and scavenger receptors, responsible for uptake of modified lipids (CD36, ScR-A1, CXCL16 and LOX-1), were evaluated by real-time PCR and confirmed with Western blot. DiI-oxidized LDL internalization assay was used to assess foam cell formation. The influence of MPA was also evaluated in BMDM obtained from atherosclerosis-prone transgenic mice, ApoE^-/- and ApoE^-/-Fas^-/-.

RESULTS

In M0 macrophages, MPA increased expression of ABCA1 and CXCL16 in a concentration-dependent manner. In M1 THP-1 macrophages, MPA caused a significant increase of 27-hydroxylase mRNA and CD36 and SR-A1 receptor mRNAs. Exposure of M2 macrophages to MPA also stimulated expression of 27-hydroxylase, while downregulating all evaluated scavenger receptors. In contrast, CsA had no impact on cholesterol efflux in M0 and M1 macrophages, but significantly augmented expression of ABCA1 and 27-hydroxylase in M2 macrophages. CsA significantly increased expression of the LOX1 receptor in naïve macrophages, downregulated expression of CD36 and SR-A1 in the M1 subpopulation and upregulated expression of all evaluated scavenger receptors. However, CsA enhanced foam cell transformation in M0 and M2 macrophages, while MPA had no effect on foam cell formation unless used at a high concentration in the M2 subtype.

CONCLUSIONS

Our results clearly underline the importance of further evaluation of the effects of these drugs when used in atherosclerosis-prone patients with autoimmune or renal disease.

Early pharmacokinetics of low dosage mycophenolate exposure in Thai kidney transplant recipients

Background The effects of mycophenolic acid exposure in the early period after transplantation on clinical outcomes have been reported; however, mycophenolic acid exposure in the early period after transplantation in Asian kidney transplant recipients who receive 1.5 g/d mycophenolate mofetil has never been investigated. Objective To determine mycophenolic acid exposure on day 3 post-transplantation in kidney transplant recipiens who receive 1.5 g/d mycophenolate mofetil. The effects of the reduced renal function on mycophenolic acid area under the concentration-time curve (AUC) and the achievement of the target AUC on the incidence of biopsy proven acute rejection during the first month post-transplantation were also evaluated. Setting A university hospital Method Blood samples and 24-h urine were collected on day 3 post-transplantation. Main outcome measures The mycophenolic acid AUC was calculated by linear trapezoidal rule and compared with the target of 45 mg*h/L. Results Of 42 Thai kidney transplant recipiens, the mean mycophenolic acid AUC of 45.1 mg*h/L (SD 14.7) was comparable to the AUC target (P = 0.962). Significant differences of the mycophenolic acid AUC were observed between patients with urine output of < 2400 mL and those with urine output ≥ 2400 mL (35.3 ± 6.6 and 47.4 ± 15.2, respectively; P = 0.002), and between patients with 24-h measured CrCl < 25 mL/min and those with CrCl ≥ 25 mL/min (38.0 (29.0, 42.2) and 49.2 ± 14.0, respectively; P = 0.017). Proportions of overall biopsy proven acute rejection among patients with mycophenolic acid AUC of < 45 and ≥ 45 mg*h/L were comparable (20.0% and 23.5%, respectively; P = 1.000). Conclusions After the starting dosage of 1.5 g/d mycophenolate mofetil, the mean mycophenolic acid AUC on day 3 post-kidney transplantation is comparable with the target of 45 mg*h/L. Severely reduced renal function significantly influences mycophenolic acid exposure.

Low incidence of acute rejection within 6 months of kidney transplantation in HIV-infected recipients treated with raltegravir: the Agence Nationale de Recherche sur le Sida et les Hépatites Virales (ANRS) 153 TREVE trial

OBJECTIVES

High rates of clinical acute rejection after kidney transplantation have been reported in people living with HIV (PLHIV), probably as a consequence of drug interactions. We therefore investigated the incidence of acute rejection within 6 months of transplantation in HIV-infected recipients treated with a protease-inhibitor-free raltegravir-based regimen.

METHODS

The Agence Nationale de Recherche sur le Sida et les Hépatites Virales (ANRS) 153 TREVE (NCT01453192) study was a prospective multicentre single-arm trial in adult PLHIV awaiting kidney transplantation, with viral load < 50 HIV-1 RNA copies/mL, CD4 T-cell count > 200 cells/μL, and HIV-1 strains sensitive to raltegravir, aiming to demonstrate 6-month clinical acute rejection rates < 30%. Time to transplantation was compared with that for uninfected subjects matched for age, sex and registration date.

RESULTS

In total, 61 participants were enrolled in the study, and 26 underwent kidney transplantation. Two participants experienced clinical acute rejection, corresponding to an estimated clinical acute rejection rate of 8% [95% confidence interval (CI) 2-24%] at 6 and 12 months post-transplantation. HIV infection remained under control in all but one participant, who temporarily stopped antiretroviral treatment. Median time to transplantation was longer in PLHIV than in controls (4.3 versus 2.8 years, respectively; P = 0.002) and was not influenced by blood group.

CONCLUSIONS

Acute rejection rates were low after kidney transplantation in PLHIV treated with a raltegravir-based regimen. However, PLHIV have poorer access to transplantation than HIV-uninfected individuals after registration on the waiting list.

Immunosuppressants in Organ Transplantation

The goal of immunosuppressive therapy post-transplantation in pediatric renal transplant recipients is to prevent acute and chronic rejection while minimizing drug side effects. Most therapies alter immune response mechanisms but are not immunologically specific, and a careful balance is required to find the dose that prevents rejection of the graft while minimizing the risks of overimmunosuppression leading to infection and cancer. While this chapter because of space constraints focuses on immunosuppressive therapy in pediatric renal transplant recipients, many aspects can be applied on pediatric recipients of other solid organ transplants such as the liver and heart. The major maintenance immunosuppressive agents currently used in various combination regimens are tacrolimus, cyclosporine, mycophenolate mofetil, azathioprine, everolimus, sirolimus, and glucocorticoids (steroids). Although data from adult renal transplantation trials are used to help guide management decisions in pediatric patients, immunosuppressive therapy in pediatric renal transplant recipients often must be modified because of the unique dosage requirements and clinical effects of these agents in children, including their impact on growth and development. The optimal immunosuppressive therapy post-transplant is not established. The goal remains to find the best combination of immunosuppressive agents that optimizes allograft survival by preventing acute rejection while limiting drug toxicities.

Review of approaches and examples for monitoring biotransformation in protein and peptide therapeutics by MS

Biotherapeutic drugs have emerged in quantity in pharmaceutical pipelines, and increasingly diverse biomolecules are progressed through preclinical and clinical development. As purification, separation, mass spectrometer detection and data processing capabilities improve, there is opportunity to monitor drug concentration by traditional ligand-binding assay or MS measurement and to monitor metabolism, catabolism or other biomolecular mass variants present in circulation. This review highlights approaches and examples of monitoring biotransformation of biotherapeutics by MS as these techniques are poised to add value to drug development in years to come. The increased use of such approaches, and the successful quantitation of biotherapeutic structural modifications, will provide insightful data for the benefit of both researchers and patients.

Replacement of mycophenolate mofetil with a JAK inhibitor, AS2553627, in combination with low-dose tacrolimus, for renal allograft rejection in non-human primates

In renal transplant patients, using mycophenolate mofetil (MMF) with calcineurin inhibitors (CNIs; cyclosporine and tacrolimus [TAC]) has led to a significant improvement in graft survival. However, reducing or withholding MMF due to its gastrointestinal adverse events increases rejection risk. CNI-sparing strategies are important to avoid CNI-related nephrotoxicity in clinical settings. Here, we investigated AS2553627, a JAK inhibitor replacing MMF in combination with a sub-therapeutic dose of TAC to treat allograft rejection in a monkey model. AS2553627 inhibited proliferation of IL-2 stimulated T cells with little species difference between monkeys and humans. In MMF monotherapy, oral administration of 20 or 40 mg/kg/day prolonged graft survival with median survival times (MSTs) of 16.5 days and 33 days, respectively, whereas untreated animals showed MST of 6 days. In MMF/TAC (1 mg/kg/day, p.o.) combination therapy, pharmacokinetic analysis indicated that MMF 20 mg/kg/day achieved the clinical target AUC_0-24h and prolonged renal allograft survival, with MST of 24 days. Oral administration of AS2553627 0.24 mg/kg/day in combination with TAC significantly prolonged renal allograft survival to MST of >90 days with low plasma creatinine levels. Histopathological analysis revealed that acute T cell-mediated rejection events such as vasculitis and interstitial mononuclear cell infiltration were significantly inhibited in AS2553627/TAC-treated allografts compared with MMF/TAC-treated allografts. All AS2553627/TAC-treated monkeys surviving >90 days exhibited less interstitial fibrosis/tubular atrophy than monkeys in the MMF/TAC group. These results suggest that AS2553627 replacing MMF is an attractive CNI-sparing strategy to prevent renal allograft rejection.

Mycophenolic acid concentrations in peripheral blood mononuclear cells are associated with the incidence of rejection in renal transplant recipients

AIMS

Although therapeutic drug monitoring of plasma mycophenolic acid (MPA) concentrations has been recommended to individualize dosage in transplant recipients, little is known regarding lymphocyte concentrations of MPA, where MPA inhibits inosine monophosphate dehydrogenase (IMPDH). This study investigated the utility of measuring predose MPA concentrations in peripheral blood mononuclear cells (C_0C ) and predose IMPDH activity, as predictors of graft rejection in renal transplant recipients.

METHODS

Forty-eight patients commencing mycophenolate mofetil (1 g twice daily) in combination with tacrolimus and prednisolone were recruited. Blood was collected for determination of trough total (C_0P ) and unbound (C_0u ) plasma MPA concentrations. Peripheral blood mononuclear cells were isolated for determination of C_0C and IMPDH activity. The incidence of rejection within 2 days of sample collection was determined histologically and classified according to the Banff 2007 criteria.

RESULTS

There was no association between MPA C_0C and C_0P (r_s  = 0.28, P = 0.06), however, MPA C_0C were weakly correlated with MPA C_0u (r_s  = 0.42, P = 0.013). Multivariate analysis indicated that MPA C_0C was the only covariate independently associated with rejection (FDR-adjusted P = 0.033). The receiver operating characteristic area under the curve (AUC) for the prediction of severe rejection using MPA C_0C was 0.75 (P = 0.013), with 73% sensitivity and specificity at a C_0C threshold of 0.5 ng 10^-7 cells. However, predose IMPDH activity was not a predictor of rejection (P > 0.15).

CONCLUSIONS

MPA C_0C measurement within the early post-transplant period may be useful to facilitate early titration of MPA dosing to significantly reduce rejection.

Clinical Implication of Mycophenolic Acid Trough Concentration Monitoring in Kidney Transplant Patients on a Tacrolimus Triple Maintenance Regimen: A Single-Center Experience

Background

This study was designed to analyze the clinical implications of mycophenolic acid trough concentration monitoring.

Material/Methods

We collected data of patients with mycophenolic acid trough concentration monitoring after their first kidney transplant between November 2006 and March 2015 who were prescribed tacrolimus, mycophenolate, and methylprednisolone. Analyses were performed on 3 periods: 1 month, 1 month to 1 year, and after 1 year post-transplantation. To analyze factors related to acute cellular rejection, logistic regression was used for 1 month, while Cox analysis was used during 1 month to 1 year and after 1 year post-transplantation.

Results

In the 145 patients receiving mycophenolate mofetil, mean tacrolimus trough ≥7.0 ng/mL (OR=0.177, CI=0.060–0.524, p=0.002) and mean mycophenolic acid trough ≥1.7 mg/L (OR=0.190, CI=0.040–0.896, p=0.036) were protective for rejection during 1 month. Mean mycophenolic acid trough ≥1.7 mg/L (HR=0.179, CI=0.040–0.806, p=0.025) and ≥0.7 mg/L (HR=0.142, CI=0.028–0.729, p=0.019) were related to better rejection-free survival during 1 month to 1 year and after 1 year, respectively. In 399 patients receiving enteric-coated mycophenolate sodium, mean tacrolimus trough ≥7.0 ng/mL (OR=0.258, CI=0.131–0.507, p<0.001) and mean mycophenolic acid trough ≥2.1 mg/L (OR=0.507, CI=0.264–0.973, p=0.041) were protective for rejection during 1 month. Mean mycophenolic acid trough ≥1.7 mg/L (HR=0.519, CI=0.289–0.932, p=0.028) and ≥0.7 mg/L (HR=0.208, CI=0.072–0.602, p=0.004) were related to better rejection-free survival during 1 month to 1 year and after 1 year, respectively.

Conclusions

Mycophenolic acid trough concentration monitoring can be useful in preventing acute cellular rejection in patients receiving tacrolimus, mycophenolate, and methylprednisolone.

Estimation of Mycophenolic Acid Area Under the Curve With Limited-Sampling Strategy in Chinese Renal Transplant Recipients Receiving Enteric-Coated Mycophenolate Sodium

BACKGROUND

The enteric-coated mycophenolate sodium (EC-MPS), whose active constituent is mycophenolic acid (MPA), has been widely clinically used for organ transplant recipients. However, its absorption is delayed due to its special designed dosage form, which results in difficulty to monitor the exposure of the MPA in patients receiving the EC-MPS. This study was aimed at developing a relatively practical and precise model with limited sampling strategy to estimate the 12-hour area under the concentration-time curve (AUC0-12 h) of MPA for Chinese renal transplant recipients receiving EC-MPS.

METHODS

A total of 36 Chinese renal transplant recipients receiving the EC-MPS and tacrolimus were recruited in this study. The time point was 2 weeks after the transplantation for all the patients. The MPA concentrations were measured with enzyme-multiplied immunoassay technique for 11 blood specimens collected predose and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, and 12 hours after the morning dose of EC-MPS. The measured AUC was calculated with these 11 points of MPA concentrations with the linear trapezoidal rule. Limited sampling strategy was used to develop models for estimated AUC in the model group (n = 18). The bias and precision of different models were evaluated in the validation group (n = 18).

RESULTS

C4 showed the strongest correlation with the measured AUC. The best 3 time point equation was 6.629 + 8.029 × C0 + 0.592 × C3 + 1.786 × C4 (R = 0.910; P < 0.001), whereas the best 4 time point equation was 3.132 + 5.337 × C0 + 0.735 × C3 + 1.783 × C4 + 3.065 × C8 (R = 0.959; P < 0.001). When evaluated in the validation group, the 4 time point model had a much better performance than the 3 time point model: for the 4 time point model: R = 0.873, bias = 0.505 [95% confidence interval (CI), -10.159 to 11.170], precision = 13.370 (95% CI, 5.186-21.555), and 77.8% of estimated AUCs was within 85%-115% of the measured AUCs; for the 3 time point model: R = 0.573, bias = 6.196 (95% CI, -10.627 to 23.018), precision = 21.286 (95% CI, 8.079-34.492), and 50.0% of estimated AUCs was within 85%-115% of the measured AUCs.

CONCLUSIONS

It demanded at least 4 time points to develop a relatively reliable model to estimate the exposure of MPA in renal transplant recipients receiving the EC-MPS. The long time span needed restricted its application, especially for the outpatients, but it could be a useful tool to guide the personalized prescription for the inpatients.

Renal Transplant Acute Rejection with Lower Mycophenolate Mofetil Dosing and Proton Pump Inhibitors or Histamine-2 Receptor Antagonists

BACKGROUND

Pharmacokinetic data show reduced mycophenolic acid levels in renal transplant recipients taking mycophenolate mofetil (MMF) and proton pump inhibitors (PPIs) concomitantly. This reduced exposure could increase rejection risk. The typical initial MMF dose post renal transplantation is 2 g/day, which often requires dose reduction secondary to side effects. Existing studies have not shown significant acute rejection differences for patients taking MMF-PPI versus patients taking MMF-ranitidine.

OBJECTIVE

The purpose of this study was to evaluate clinical outcomes in renal transplant recipients receiving a lower MMF dose than previously studied (1.5 g/day) and either a PPI or histamine-2 receptor antagonist (H2RA).

METHODS

This retrospective cohort study included adult subjects receiving a renal transplant between January 1, 2009, and June 30, 2013. Comparison groups were defined based on acid-suppressing therapy class prescribed at discharge from transplantation. The primary outcome was acute rejection incidence within 1 year posttransplantation.

RESULTS

Of 728 renal transplant recipients screened, 522 were included: 183 taking a PPI and 339 taking an H2RA. There was no significant difference in acute rejection within 1 year (H2RA 19% versus PPI 14%, p=0.12) or 3 months (4% vs 5%, p=0.44, respectively) posttransplantation. Maintenance immunosuppression (MMF dose and tacrolimus troughs) was similar between groups at 3 months and 1 year. Graft and patient survivals were favorable (> 95%), and graft function at 1 year was stable and similar between groups.

CONCLUSION

Despite taking lower MMF doses than previously studied, subjects on a PPI compared to an H2RA were not at increased risk of acute rejection within 1 year posttransplantation.