Optimizing the dose of mycophenolate mofetil for the maintenance treatment of lupus nephritis by therapeutic drug monitoring

Optimal exposure of mycophenolic acid for induction therapy of childhood lupus nephritis patients: an observational cohort study

OBJECTIVES

Mycophenolic acid (MPA) is recommended for lupus nephritis (LN) treatment, but with large inter-individual variability in pharmacokinetics (PK). The aim of this study is to reveal the relationship between MPA exposure and disease response and adverse drug reactions in pediatric LN patients.

METHOD

This was a population-based observational cohort study. A total of 86 pediatric LN patients treated with mycophenolate mofetil (MMF) for induction therapy were enrolled. The area-under the concentration-time curve (AUC) was calculated using MPA concentrations according to a limited sampling strategy. Receiver operating characteristic analysis was performed to assess the MPA-AUC threshold values. The cumulative incidence of renal remission and inactive systemic lupus erythematosus (SLE) over time was evaluated by Kaplan-Meier's analysis.

RESULTS

MPA-AUC was identified as an independent factor associated with renal remission and lupus activity at 6 and 12 months after MMF treatment, and the improved renal remission rates were correlated with higher MPA-AUC, with thresholds of 29.81 and 30.63 μg·h·mL-1 at 6 months and 12 months, respectively. Furthermore, the thresholds for maintaining the hypoactive state of LN were 30.96 and 31.19 μg·h·mL-1at 6 months and 12 months, respectively. Patients reaching target thresholds for MPA-AUC achieved renal response or stable disease earlier. In addition, the MPA-AUC threshold for decreasing MMF-related adverse reactions was 50.80 μg·h·mL-1.

CONCLUSION

The initial and long-term treatments of pediatric LN patients with MMF should be individualized according to the MPA-AUC, and the recommended MPA exposure is 31.19-50.80 μg·h·mL-1.

Therapeutic drug monitoring of mycophenolic acid and clinical outcomes of lupus nephritis: a systematic review and meta-analysis

INTRODUCTION

Mycophenolic acid (MPA) is a primary immunosuppressive agent used in the treatment of lupus nephritis (LN). While therapeutic drug monitoring (TDM) of MPA is well established in organ transplantation, its role in LN treatment remains uncertain. Our objective was to review and summarise current knowledge on TDM of MPA in the LN treatment.

METHODS

A systematic search was conducted in the online databases, specifically targeted patients diagnosed with LN receiving MPA treatment. The included studies had to report both MPA pharmacokinetic parameters and renal outcomes. A random-effects model meta-analysis was conducted to assess the relationship between clinical responses and MPA pharmacokinetics.

RESULTS

A total of 1507 studies were initially screened, resulting in the inclusion of 16 studies for meta-analysis, encompassing 433 patients. The response group exhibited significantly higher MPA area under the concentration-time curve (AUC) compared with the non-response group (51.44±21.73 mg·h/L vs 30.30±16.24 mg·h/L). The weighted mean difference (WMD) of MPA-AUC between responders and non-responders was 16.83 mg·h/L (95% CI 10.59 to 23.06; p<0.001). Similarly, trough concentration (C0) of MPA showed a strong association with renal response, evidenced by C0 values of 2.50±1.73 mg/L in the response group vs 1.51±1.33 mg/L in the non-response group (WMD 1.37 mg/L; 95% CI 0.77 to 1.97; p<0.001). There was no significant relationship identified between MPA-AUC and adverse events.

CONCLUSION

This meta-analysis emphasised the meaningful correlation between MPA AUC and C0 with renal response in LN treatment. Randomised controlled trials are necessary to validate this approach and determine its superiority over fixed dosing in the context of LN treatment.

Perspectives on Mycophenolate Mofetil in the Management of Autoimmunity

Before becoming a cornerstone in the treatment of numerous immune-mediated diseases, mycophenolate mofetil (MMF) was first introduced as an immunosuppressive agent in transplant immunology and later received the attention of rheumatologists and clinicians involved in the management of autoimmune diseases. MMF is now a widespread immunosuppressive drug for the treatment of several conditions, including lupus nephritis, interstitial lung disease associated with systemic sclerosis, and anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis while being efficacious also as rescue therapy in various orphan diseases, including dermatomyositis and IgA-associated nephropathy. Similarly, case reports or series support a possible use of MMF in other rare autoimmune diseases. Beyond modulating lymphocyte activation, MMF acts on other immune and non-immune cells and these effects may explain the therapeutic profile of this medication. The effects of MMF are broadly characterized by the impact on the immune system and the antiproliferative and antifibrotic changes induced. In this latter case, mechanistic data on fibroblasts may in the future allow to reevaluate the use of MMF in selected patients with inflammatory arthritis or systemic sclerosis. Attention must be paid towards the possible occurrence of adverse events, such as gastrointestinal complaints and teratogenicity, while the risk of infections and cancer related to MMF needs to be further investigated.

Pharmacokinetics and pharmacodynamics profiles of enteric-coated mycophenolate sodium in female patients with difficult-to-treat lupus nephritis

Relapsed or resistant lupus nephritis (LN) is considered a difficult-to-treat type of LN, and enteric-coated mycophenolate sodium (EC-MPS) has been used in this condition. Therapeutic drug monitoring using the area under the plasma mycophenolic acid concentration from 0 to 12 h postdose (MPA-AUC_0-12h ) ≥45 μg.h/ml is a useful approach to achieve the highest efficiency. This study assessed EC-MPS's pharmacokinetic (PK) and pharmacodynamic (PD) profiles and investigated an optimal level of the single time point of plasma MPA concentration. Nineteen biopsy-proven patients with class III/IV LN received 1440 mg/day of EC-MPS for 24 weeks. PK (maximum plasma MPA concentration [C_max ], time to C_max , and MPA-AUC_0-12h ) and PD (activity of inosine-5'-monophosphate dehydrogenase [IMPDH]) parameters were measured at weeks 2, 8, 16, and 24. We found that IMPDH activity decreased from baseline by 31-42% within 2-4 h after dosing, coinciding with the increased plasma MPA concentration. MPA-AUC_0-12h ≥45 μg.h/ml was best predicted by a single time point MPA concentration at C0.5, C2, C3, C4, and C8 (r²  = 0.516, 0.514, 0.540, 0.611, and 0.719, respectively), independent of dose, albumin, urine protein/creatinine ratio, and urinalysis. The MPA-C0.5 cutoff of 2.03 g/ml yielded the highest overall sensitivity of 85% and specificity of 88.2% in predicting MPA-AUC_0-12h ≥45 μg.h/ml. A single timepoint of plasma MPA-C0.5 ≥2.03 μg/ml may help guide EC-MPS adjustment to achieve adequate drug exposure. Further study of EC-MPS used to validate this cutoff is warranted.

The use of mycophenolate mofetil area under the curve

PURPOSE OF REVIEW

Although mycophenolate mofetil (MMF) has been used successfully to treat a myriad of autoimmune diseases, its complex pharmacokinetics make it difficult to determine the true drug exposure for an individual patient. This review summarizes the body of literature focused on the gold standard measurement of the area under the curve (AUC) of mycophenolic acid (MPA), the active metabolite of MMF.

RECENT FINDINGS

Fixed dosing of MMF leads to highly variable drug exposure. Retrospective series have reported improved clinical outcomes when a minimum AUC value from 0 to 12 h (AUC0-12h) ≥30 mg h/l is achieved. MPA levels are affected by various drug interactions, hypoalbuminemia, and renal insufficiency and the measurement of free rather than total MPA levels is prudent in some situations. A limited number of studies employing prospective dose adjustment of MMF based on AUC0-12h measurements have yielded mixed results.

SUMMARY

Given the wide range of MPA AUC encountered in autoimmune diseases, dose adjustments of MMF based on AUC rather than fixed dosing of MMF should be considered in both clinical practice and clinical trials. Limited sampling strategies have been proposed to improve clinical feasibility of measurements, but a standard is yet to be defined.

Mycophenolic acid area under the concentration-time curve is associated with therapeutic response in childhood-onset lupus nephritis

BACKGROUND

Mycophenolic acid (MPA), the active compound of mycophenolate mofetil (MMF), is widely used in lupus nephritis treatment. Therapeutic drug monitoring of adults suggests that area under the concentration-time curve (AUC) of MPA (MPA-AUC) is associated with clinical outcomes, but childhood data are scarce.

METHODS

Retrospective study of 27 children with biopsy-proven lupus nephritis treated with MMF between 2008 and 2016. In 25 children, MPA-AUC was performed within 6 months after kidney biopsy and MMF initiation. Treatment response at 6 months was defined as normal or improved GFR by 25% compared with baseline, 50% reduction of proteinuria to < 0.5 g/day or 50 mg/mmol, and no hematuria.

RESULTS

A total of 62 MPA-AUC were analyzed in 27 patients. Overall median was 44 mg h/L (interquartile range [IQR] 33-54). Individual dose adaptation was required in 32 cases (52%) to achieve target AUC of 30-60 mg h/L. At 6 months, 14/25 patients were defined as responders (56%, median MPA-AUC 49 mg h/L (40-59)) and 11/25 as non-responders (44%, 29 mg h/L (24-38)). Patients with MPA-AUC levels > 45, 30-45, and < 30 mg h/L had 6-month response rates of 89% (8/9), 60% (6/10), and 0% (0/6), respectively. In a logistic regression model adjusted for age, sex, lupus nephritis classification, and time since MMF initiation, an MPA-AUC > 45 mg h/L was significantly associated with therapeutic response (OR 3.6, 95% CI 2.4-9.5, p = 0.03).

CONCLUSIONS

Therapeutic drug monitoring leading to individualized dosing may improve efficacy of MMF. MPA-AUC > 45 mg h/L is associated with better response rate and may be considered as a target value in pediatric lupus nephritis.

Real-World Experience of Safety of Mycophenolate Mofetil in 119 Japanese Patients with Systemic Lupus Erythematosus: A Retrospective Single-Center Study

Objectives

Mycophenolate mofetil (MMF) is the standard treatment for lupus nephritis. In Japan, it was approved for lupus nephritis in 2015. We investigated its real-world safety and effectiveness in Japanese patients with systemic lupus erythematosus (SLE).

Methods

We analyzed the continuation rate, adverse events, and reasons for discontinuation of MMF in Japanese patients with SLE in a retrospective single-center study. We included 119 patients who received MMF from 31 July 2015 to 31 May 2019. To compare demographic and clinical characteristics between groups, the Mann–Whitney U-test was used for nonnormally distributed variables. Categorical variables were compared using Fisher's exact test. Kaplan–Meier curves were plotted for the discontinuation rate of MMF.

Results

Patients consisted of 18 males and 101 females. Thirty-five patients discontinued MMF. The cumulative discontinuation rate was 42.4%. Twenty-nine patients discontinued MMF due to adverse events, and six patients discontinued MMF due to remission of SLE or desire for childbearing. At the time of the last observation, the lupus low disease activity state achievement rate was significantly lower in patients who experienced adverse events than those who did not (64% vs. 35%, P = 0.009). We examined the concentration of mycophenolate acid (trough level) in stored frozen serum in 11 patients. Two patients had irreversible complications due to viral meningitis; their trough mycophenolate acid concentrations were 8.3 and 6.3 μg/mL, respectively.

Conclusions

Although MMF may be effective in Japanese patients with SLE, physicians should pay attention to infections in patients with high mycophenolate acid concentrations.

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.

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.

High plasma mycophenolate acid concentration in the early phase of induction therapy predicts good renal outcome in lupus nephritis

Objectives: To identify the prognostic predictive factor of complete renal response (CR) at week 12 by focusing on the plasma mycophenolic acid (MPA) concentration in induction therapy in lupus nephritis.Methods: We prospectively enrolled patients with biopsy-proven LN class III/IV who were hospitalized between 2016 and 2017. As an induction therapy, mycophenolate mofetil was continuously introduced at 2000 mg/day. We measured the MPA plasma concentration at two time points depending on the induction therapy phase, early (week 4) or middle (week 12). The association between these concentrations and CR rate at week 12 was evaluated.Results: Ten patients were enrolled. A significantly higher AUC_0-12 between 0 and 12 h of MPA at the early phase was observed in the patients with CR at week 12 than in those without (p = .03). All the patients with high MPA-AUC_0-12 (> 40 mg h/L) at the early phase achieved CR at week 12, but no such association was found at the middle phase. The multivariate analysis revealed that MPA-AUC0-12 was selected as an independent predictive factor of CR at week 12 (odds ratio: 1.12; 95% confidence interval: 1.01-1.45, p = .02).Conclusion: The high AUC_0-12 of MPA at the early phase of induction therapy may predict good renal response.

Complications of Immunosuppression in Glomerular Disease

Most glomerular diseases are immunologically mediated disorders of the kidney and are common causes of ESKD. In addition to supportive therapy, a wide range of immunosuppressive agents are used in the management of patients with these conditions. Immunosuppression requires a careful balance of risk and benefits, and many of these agents have a narrow therapeutic window and require close monitoring. This review describes the side effects of immunosuppressive agents used in recent randomized, controlled trials of glomerular disease, and highlights some of the key adverse events that determine the choice and prescription of these medications.

Ex vivo binding of the immunosuppressant mycophenolic acid to dog and cat plasma proteins and the effect of co-incubated dexamethasone and prednisolone

Mycophenolic acid (MPA) has been shown to be promising for the treatment of autoimmune diseases in dogs and cats. In humans, MPA is highly bound to plasma proteins (~97%). It has been recommended to monitor free drug plasma concentrations because the free MPA correlates with its immunosuppressive effect. However, it is unknown if MPA is highly bound to plasma proteins in dogs and cats. The objectives of this study were to determine the extent of plasma protein binding of MPA and evaluate the effect of prednisolone and dexamethasone on the extent of protein binding of MPA in dogs and cats. The extent of plasma protein binding of MPA was determined in plasma collected from clinically healthy adult cats (n = 13) and dogs (n = 14) by combining high-throughput dialysis and ultra-high-liquid chromatography. This study reveals that MPA is highly bound to plasma proteins (>90%) in dogs and cats, mean extent of binding of MPA at 15 μg/ml to plasma proteins being 96% (range, 95%-97%) and 92% (range, 90%-93%) for dogs and cats, respectively. In dog plasma, MPA is primarily bound to albumin. In vitro, prednisolone increased the unbound MPA in dogs (p < .01) but not in cats (p = .07) while dexamethasone had no effect on MPA plasma binding in either species (p > .05). Results of this study provide valuable information for designing future pharmacokinetic and pharmacodynamic studies and also therapeutic monitoring programs for dogs and cats.

Effects of diammonium glycyrrhizinate on hepatic and intestinal UDP-Glucuronosyltransferases in rats: Implication in herb-drug interactions

Glycyrrhizin is a major bioactive component of liquorice, which exerts multiple biochemical and pharmacological activities and is frequently used in combination with other drugs in the clinic. Mycophenolate mofetil (MMF), an immunosuppressant widely used in transplant patients, is metabolized by UDP-glucuronyltransferases (UGTs). Although significant evidence supports that glycyrrhizin could interact with the cytochrome P450s (CYPs), few studies have addressed its effects on UGTs. The present study aimed at investigating the regulatory effects of diammonium glycyrrhizinate (GLN) on UGTs in vitro and in vivo. We found that long-term administration of GLN in rats induced overall metabolism of MMF, which might be due to the induction of UGT1A protein expression. Hepatic UGT1A activity and UGT1A mRNA and protein expression were significantly increased in GLN-treated rats. UGT1A expression levels were also increased in the intestine, contradicting with the observed decrease in intestinal UGT1A activities. This phenomenon may be attributed to different concentrations of glycyrrhetinic acid (GA) in liver and intestine and the inhibitory effects of GA on UGT1A activity. In conclusion, our study revealed that GLN had multiple effects on the expression and activities of UGT1A isoforms, providing a basis for a better understanding of interactions between GLN and other drugs.

Mycophenolic Acid Pharmacokinetics and Relapse in Children with Steroid-Dependent Idiopathic Nephrotic Syndrome

BACKGROUND AND OBJECTIVES

Therapeutic drug monitoring of mycophenolic acid can improve clinical outcome in organ transplantation and lupus, but data are scarce in idiopathic nephrotic syndrome. The aim of our study was to investigate whether mycophenolic acid pharmacokinetics are associated with disease control in children receiving mycophenolate mofetil for the treatment of steroid-dependent nephrotic syndrome.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a retrospective multicenter study including 95 children with steroid-dependent nephrotic syndrome treated with mycophenolate mofetil with or without steroids. Area under the concentration-time curve of mycophenolic acid was determined in all children on the basis of sampling times at 20, 60, and 180 minutes postdose, using Bayesian estimation. The association between a threshold value of the area under the concentration-time curve of mycophenolic acid and the relapse rate was assessed using a negative binomial model.

RESULTS

In total, 140 areas under the concentration-time curve of mycophenolic acid were analyzed. The findings indicate individual dose adaptation in 53 patients (38%) to achieve an area under the concentration-time curve target of 30-60 mg·h/L. In a multivariable negative binomial model including sex, age at disease onset, time to start of mycophenolate mofetil, previous immunomodulatory treatment, and concomitant prednisone dose, a level of area under the concentration-time curve of mycophenolic acid >45 mg·h/L was significantly associated with a lower relapse rate (rate ratio, 0.65; 95% confidence interval, 0.46 to 0.89; P=0.01).

CONCLUSIONS

Therapeutic drug monitoring leading to individualized dosing may improve the efficacy of mycophenolate mofetil in steroid-dependent nephrotic syndrome. Additional prospective studies are warranted to determine the optimal target for area under the concentration-time curve of mycophenolic acid in this population.

Pharmacokinetics of mycophenolate mofetil in Omani patients on cyclosporine or tacrolimus

BACKGROUND

Mycophenolate mofetil (MMF) reduces rejection in organ transplantation and is effective in controlling autoimmune diseases. Determining the area under the receiver operating characteristic curve (AUC) of MMF is not routine despite interindividual variability. The aim of this study was to look into MMF-AUC in Omani patients on cyclosporine (CsA) or tacrolimus (Tac).

METHODS

We measured MMF-AUC in 27 stable Omani patients. We used the 4-time-points-limited sampling strategy.

RESULTS

Sixteen, 8, and 3 recipients were receiving Tac, CsA, and calcineurin inhibitor (CNI)-free regimens, respectively. The mean MMF dose was 1,685 ± 442 mg/d. All except 3 patients were within or above the target AUC. The AUC was significantly higher in patients receiving Tac versus CsA. All patients on Tac were within or above the target AUC. Seven of the 8 patients with MMF-AUC above target were receiving Tac. Two of the 3 patients with MMF-AUC below target were on CsA.

DISCUSSION

These preliminary results confirm the significant interindividual variability of MMF-AUC. None of the recipients on Tac had an AUC below target. Most patients above the target AUC were receiving Tac. Two of the 3 patients with MMF-AUC below target were on CsA and receiving 1 g/d MMF. Patients on Tac are at risk of having higher than the target AUC, exposing them to overimmunosuppression. Recipients on CsA seem to require >1 g/d MMF.

CONCLUSIONS

These preliminary results encourage measuring the AUC of MMF. The fixed MMF dose regimen seems to be unreliable to predict the AUC. Preventing under- or overimmunosuppression offsets the burden.