Novel assays of multiple lymphocyte functions in whole blood measure: new mechanisms of action of mycophenolate mofetil in vivo

Personalized Therapy for Mycophenolate: Consensus Report by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

ABSTRACT

When mycophenolic acid (MPA) was originally marketed for immunosuppressive therapy, fixed doses were recommended by the manufacturer. Awareness of the potential for a more personalized dosing has led to development of methods to estimate MPA area under the curve based on the measurement of drug concentrations in only a few samples. This approach is feasible in the clinical routine and has proven successful in terms of correlation with outcome. However, the search for superior correlates has continued, and numerous studies in search of biomarkers that could better predict the perfect dosage for the individual patient have been published. As it was considered timely for an updated and comprehensive presentation of consensus on the status for personalized treatment with MPA, this report was prepared following an initiative from members of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT). Topics included are the criteria for analytics, methods to estimate exposure including pharmacometrics, the potential influence of pharmacogenetics, development of biomarkers, and the practical aspects of implementation of target concentration intervention. For selected topics with sufficient evidence, such as the application of limited sampling strategies for MPA area under the curve, graded recommendations on target ranges are presented. To provide a comprehensive review, this report also includes updates on the status of potential biomarkers including those which may be promising but with a low level of evidence. In view of the fact that there are very few new immunosuppressive drugs under development for the transplant field, it is likely that MPA will continue to be prescribed on a large scale in the upcoming years. Discontinuation of therapy due to adverse effects is relatively common, increasing the risk for late rejections, which may contribute to graft loss. Therefore, the continued search for innovative methods to better personalize MPA dosage is warranted.

Interindividual Variability in Lymphocyte Stimulation and Transcriptomic Response Predicts Mycophenolic Acid Sensitivity in Healthy Volunteers

Mycophenolic acid (MPA) is an immunosuppressant commonly used to prevent renal transplant rejection and treat glomerulonephritis. MPA inhibits IMPDH2 within stimulated lymphocytes, reducing guanosine synthesis. Despite the widespread use of MPA, interindividual variability in response remains with rates of allograft rejection up to 15% and approximately half of individuals fail to achieve complete remission to lupus nephritis. We sought to identify contributors to interindividual variability in MPA response, hypothesizing that the HPRT1 salvage guanosine synthesis contributes to variability. MPA sensitivity was measured in 40 healthy individuals using an ex vivo lymphocyte viability assay. Measurement of candidate gene expression (n ± 40) and single‐cell RNA‐sequencing (n ± 6) in lymphocytes was performed at baseline, poststimulation, and post‐MPA treatment. After stimulation, HPRT1 expression was 2.1‐fold higher in resistant individuals compared with sensitive individuals (P ± 0.049). Knockdown of HPRT1 increased MPA sensitivity (12%; P ± 0.003), consistent with higher expression levels in resistant individuals. Sensitive individuals had higher IMPDH2 expression and 132% greater stimulation. In lymphocyte subpopulations, differentially expressed genes between sensitive and resistant individuals included KLF2 and LTB. Knockdown of KLF2 and LTB aligned with the predicted direction of effect on proliferation. In sensitive individuals, more frequent receptor‐ligand interactions were observed after stimulation (P ± 0.0004), but fewer interactions remained after MPA treatment (P ± 0.0014). These data identify a polygenic transcriptomic signature in lymphocyte subpopulations predictive of MPA response. The degree of lymphocyte stimulation, HPRT1, KLF2, and LTB expression may serve as markers of MPA efficacy.

Neurotherapeutic Strategies for Multiple Sclerosis

Multiple sclerosis (MS) is the most common disabling neurologic disease of young adults. There are now 16 US Food and Drug Administration (FDA)-approved disease-modifying therapies for MS as well as a cohort of other agents commonly used in practice when conventional therapies prove inadequate. This article discusses approved FDA therapies as well as commonly used practice-based therapies for MS, as well as those therapies that can be used in patients attempting to become pregnant, or in patients with an established pregnancy, who require concomitant treatment secondary to recalcitrant disease activity.

In Vitro Influence of Mycophenolic Acid on Selected Parameters of Stimulated Peripheral Canine Lymphocytes

Mycophenolic acid (MPA) is an active metabolite of mycophenolate mofetil, a new immunosuppressive drug effective in the treatment of canine autoimmune diseases. The impact of MPA on immunity is ambiguous and its influence on the canine immune system is unknown. The aim of the study was to determine markers of changes in stimulated peripheral canine lymphocytes after treatment with MPA in vitro. Twenty nine healthy dogs were studied. Phenotypic and functional analysis of lymphocytes was performed on peripheral blood mononuclear cells cultured with mitogens and different MPA concentrations– 1 μM (10⁻³ mol/m³), 10 μM or 100 μM. Apoptotic cells were detected by Annexin V and 7-aminoactinomycin D (7-AAD). The expression of antigens (CD3, CD4, CD8, CD21, CD25, forkhead box P3 [FoxP3] and proliferating cell nuclear antigen [PCNA]) was assessed with monoclonal antibodies. The proliferation indices were analyzed in carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled cells. All analyses were performed using flow cytometry. The influence of MPA on apoptosis was dependent on the mechanism of cell activation and MPA concentration. MPA caused a decrease in the expression of lymphocyte surface antigens, CD3, CD8 and CD25. Its impact on the expression of CD4 and CD21 was negligible. Its negative influence on the expression of FoxP3 was dependent on cell stimulation. MPA inhibited lymphocyte proliferation. In conclusion, MPA inhibited the activity of stimulated canine lymphocytes by blocking lymphocyte activation and proliferation. The influence of MPA on the development of immune tolerance–expansion of Treg cells and lymphocyte apoptosis–was ambiguous and was dependent on the mechanism of cellular activation. The concentration that MPA reaches in the blood may lead to inhibition of the functions of the canine immune system. The applied panel of markers can be used for evaluation of the effects of immunosuppressive compounds in the dog.

Treatment of canine meningoencephalomyelitis of unknown aetiology with mycophenolate mofetil and corticosteroids: 25 cases (2007-2012)

The use of mycophenolate mofetil (MMF) for a variety of immune‐mediated diseases in veterinary medicine has been described. However, there is only a small number of cases documenting its use in dogs with meningoencephalomyelitis of unknown aetiology (MUE). We hypothesized that the use of MMF and corticosteroids in dogs with MUE results in comparable survival data to other published treatment protocols and is associated with limited adverse effects. A retrospective study of medical case records of dogs clinically diagnosed with MUE recorded signalment, neuroanatomic localization, magnetic resonance imaging findings, cerebrospinal fluid analysis results, medications administered, follow‐up neurologic examinations, survival and adverse events. Variables were compared between dogs which were treated with MMF within 30 days of diagnosis (immediate group) vs. dogs in which MMF therapy was started >30 days after diagnosis (delayed group). Twenty‐five cases of MUE were identified. The overall median survival time from diagnosis was 731 days (range 43–1672 days). After 1 month of MMF treatment, 92% of dogs showed improvement on a neurological examination. There was no significant effect of any recorded parameter on survival, including delayed vs. immediate initiation of MMF treatment. Dogs with delayed treatment had significantly lower clinical remission rates than dogs with immediate treatment at 6 months after starting MMF. Adverse events were identified in two cases (8%) and were characterized by mild gastrointestinal signs (vomiting and decreased appetite). Administration of MMF appears safe in dogs with MUE. The use of MMF results in comparable survival times to alternate immunosuppressive protocols.

Interleukin-2-stimulated natural killer cells are less susceptible to mycophenolate mofetil than non-activated NK cells: possible consequences for immunotherapy

In a clinical phase I/II trial, pediatric patients with high-risk malignancies were treated with ex vivo IL-2-stimulated donor natural killer (NK) cells after transplantation with haploidentical stem cells. To evaluate the potential negative effects of the immunosuppressive drug mycophenolate mofetil (MMF) used for immunotherapy, the functionality and signaling of ex vivo NK cells was investigated. Our results show that during NK cell expansion, long-term (9 days) incubation with mycophenolic acid (MPA), the active metabolite of MMF, in therapeutically relevant concentrations led to the severe inhibition of NK cell proliferation. This correlated with a significantly reduced cytokine/chemokine secretion and the inhibited acquisition of surface receptors regarding cytotoxicity (e.g., NKp30, NKp44, NKp46, NKG2D), adhesion/migration (e.g., ICAM-1/CD54, LFA-1/CD11a, CD62L, CXCR3) and activation (e.g., CD25). Moreover, MPA prevented phosphorylation of the central signaling molecules STAT-3/-4/-5, AKT and ERK1/2. In contrast, short-term (24 h) MPA incubation of IL-2-stimulated NK cells had no or only marginal effects on the activated NK cell phenotype, including receptor expression, cytokine/chemokine secretion and intracellular signaling. Further, short-term MPA incubation only moderately affected the highly cytotoxic activity of previously IL-2-stimulated NK cells. In conclusion, while long-term MPA incubation significantly compromised ex vivo NK cell functionality, previously IL-2-activated NK cells seemed to be rather resistant to short-term MPA treatment. This finding supports the use of IL-2-activated NK cells as immunotherapy, especially for patients treated with MMF after haploidentical stem cell transplantation.

Mycophenolate mofetil in multiple sclerosis: a multicentre retrospective study on 344 patients

OBJECTIVES

Mycophenolate mofetil (MMF) is an immunosuppressive agent, sometimes used as a disease-modifying therapy for multiple sclerosis (MS). Several studies have reported the relative safety of this treatment but, to date, its efficacy has rarely been described. We performed a retrospective study to assess the safety and efficacy of MMF in patients with MS.

METHODOLOGY

Three French MS centres included all of their patients treated by MMF. The main outcome criterion was annualised relapse rate (ARR) in the 1 year period after onset of MMF compared with the 1 year control period. Treatment with another immunosuppressive drug, such as mitoxantrone or cyclophosphamide, in the 2 years preceding initiation of MMF was included in a subgroup analysis. MMF safety and progression of the Expanded Disability Status Scale (EDSS) score were also assessed.

RESULTS

344 patients were included; 149 patients were previously treated with another immunosuppressant (IS group). Mean MMF treatment duration was 25.3±1.1 months. During the 1 year control period, ARR was 1.11±0.08, and for the 1 year treatment period, ARR was reduced significantly to 0.35±0.05 (p<0.0001, Wilcoxon paired test). Adverse events (occurring in 11% of patients) were mainly digestive disorders, benign infections, asthenia and transitory lymphopenia. Concerning the progression of disability, in the subgroup of patients without previous immunosuppressant treatment, EDSS remained stable between initiation and 1 year after the beginning of MMF.

INTERPRETATION

Our results suggest that MMF can improve or stabilise MS patients and can be used as an alternative therapy.

A one-year prospective, randomized, placebo-controlled, quadruple-blinded, phase II safety pilot trial of combination therapy with interferon beta-1a and mycophenolate mofetil in early relapsing-remitting multiple sclerosis (TIME MS)

BACKGROUND

Mycophenolate mofetil (MMF) is an oral DNA base synthesis inhibitor with immunomodulatory effects on B cells, T cells, and macrophages.

OBJECTIVE

To conduct a safety and tolerability pilot study of interferon beta-1a (IFN-b1a) in combination with either placebo or oral MMF in multiple sclerosis (MS).

METHODS

Twenty-four treatment-naïve R-RMS patients participated in a one-year prospective, placebo-controlled, blinded, safety pilot clinical trial. Every patient injected weekly intramuscular interferon beta-1a. The cohort was then randomized (1 : 1) to either active oral MMF or identical-appearing placebo tablets. Clinical evaluations were assessed every 3 months, along with brain MRI scans performed at baseline and repeated every 60 days for one year. Comprehensive laboratory assessments were monitored for safety, along with adverse events.

RESULTS

In this small pilot investigation, no differences were identified between the two treatment groups with respect to patient-reported adverse events, MRI metrics, or laboratory abnormalities. Notwithstanding these observations, and the limited number of patients treated, trends appeared to favor the combination therapy regimen.

CONCLUSIONS

The combination treatment regimen of interferon beta-1a and MMF appeared to be well tolerated in this pilot study. Despite the small sample size, therapeutic trends were observed in favor of combination therapy. An adequately powered controlled trial of MMF in MS appears warranted.

A randomized, blinded, parallel-group, pilot trial of mycophenolate mofetil (CellCept) compared with interferon beta-1a (Avonex) in patients with relapsing-remitting multiple sclerosis

BACKGROUND

Mycophenolate mofetil (MMF, CellCept®) has been utilized as an antirejection agent in transplant recipients and in patients with myriad autoimmune disorders including multiple sclerosis (MS).

OBJECTIVE

To investigate radiographic and clinical safety involving monotherapy use of daily oral MMF (1 g b.i.d.) versus weekly intramuscular interferon beta 1a (Avonex® at 30 mcg) in relapsing-remitting MS (RRMS).

METHODS

We organized a randomized, serial, 6-monthly, MRI-blinded, parallel-group multicenter pilot study to determine the safety of MMF versus interferon beta monotherapy in 35 untreated patients with RRMS, all of whom exhibited evidence of gadolinium (Gd) enhancement on a screening MRI of the brain. The primary outcome was the reduction in the cumulative mean number of combined active lesions (CAL), new Gd-enhancing lesions, and new T2 lesions on MRI analyses.

RESULTS

Both interferon beta and MMF appeared safe and well tolerated in the majority of patients. There was no difference between MMF therapy and the standard regimen of interferon beta therapy on the primary safety MRI endpoints of the study. However, the MMF group showed a trend toward a lower accumulation of combined active lesions, CAL, Gd and T2 lesions when compared with interferon beta treated patients.

CONCLUSIONS

The results from this pilot study suggest that the application of MMF monotherapy in MS deserves further exploration.

Inhibition of T-cell activation and proliferation by mycophenolic acid in patients awaiting liver transplantation: PK/PD relationships

Mycophenolic acid (MPA) plasma concentrations were reported to be associated with a decrease in T-cell proliferation, and in both IL-2 α-chain (CD25) and transferin receptor (CD71) expression. The aim of this study was to confirm, quantify and model these PK/PD relationships. Full profiles of MPA plasma concentrations, T-cell proliferation, intracytoplasmic IL-2 and TNF-α expression, and both CD71 and CD25 expression were collected over the 12h after dosing in 10 patients on the waiting list for liver transplantation. Data were analyzed using NONMEM(®). Both CD25 and CD71 expression and T cell proliferation clearly decreased (median of decrease from baseline 62%, 68% and 94%, respectively) with increasing MPA concentrations, in contrast to IL-2 and TNF-α expression. The CD25 and CD71 baseline expression (E(0)) and maximum effect (E(max)) were correlated with the E(0) and E(max) values of T-cell proliferation (r(2)=0.509 and r(2)=0.622, respectively). The CD25, CD71 expression and T-cell proliferation profiles were adequately fitted using a sigmoid inhibitory E(max) model. Low estimated values (≤2 mg/L) for 50% inhibitory MPA concentrations were obtained. This study confirmed a transient MPA concentration-dependent decrease in T-cells expressing CD25 and CD71 and a strong reduction of T-cell proliferation and showed that CD25 and CD71 expression was correlated with T-cell proliferation.

Enteric-coated mycophenolate sodium - current and future use in transplant patients

Mycophenolate mofetil, the morpholino ester prodrug of mycophenolic acid, is an effective immunosuppressant, although there are concerns over dose reductions and discontinuations due to gastrointestinal adverse events. Enteric-coated mycophenolate sodium (Myfortic) was formulated to improve mycophenolic acid-related upper gastrointestinal adverse events and to deliver effective mycophenolic acid protection. Enteric-coated mycophenolate sodium 720 mg and mycophenolate mofetil 1000 mg are therapeutically equivalent in de novo transplant patients. Conversion from mycophenolate mofetil to enteric-coated mycophenolate sodium in maintenance patients can be achieved without compromising safety and efficacy. Recent studies demonstrate the efficacy and tolerability of enteric-coated mycophenolate sodium in adult and pediatric renal transplant patients converted from mycophenolate mofetil, and early results also suggest that enteric-coated mycophenolate sodium can provide similar efficacy and safety as mycophenolate mofetil in de novo heart transplant patients.

Pharmacodynamic evaluation of the first dose of mycophenolate mofetil before kidney transplantation

BACKGROUND AND OBJECTIVES

The effect of mycophenolate mofetil (MMF) on T cell function has not been evaluated in patients undergoing kidney transplantation. The aim of this study was to assess the effect of 1g of MMF on T cell function, that is, intralymphocyte cytokine expression, T cell activation (CD25 and CD71), and T cell proliferation, as well as inosine monophosphate dehydrogenase (IMPDH) activity, to better understand the relationship between pharmacokinetic and pharmacodynamic markers in patients receiving the first dose of MMF before kidney transplantation.

PATIENTS

Twenty-four patients undergoing a kidney transplantation from a living donor were enrolled in this study.

RESULTS

Compared with baseline (before MMF intake), T cell proliferation (93%), IMPDH activity (74%), CD25 (46%), and CD71 (50%) expression significantly decreased during the first hour after MMF intake, in parallel to the rise in MPA concentration. Thereafter, all pharmacodynamic markers, except IMPDH activity, returned back to baseline level. There was a complex inverse relationship between pharmacokinetic and pharmacodynamic markers. The inhibition of T cell proliferation was highly correlated to IMPDH activity, but also to T cell activation markers.

CONCLUSION

The administration of MMF to patients is associated not only with a dramatic decrease in both T cell proliferation and IMPDH activity, but also with in a decrease in CD25 and CD71 expression.

Pharmacodynamic monitoring of the immunosuppressive therapy in patients after heart transplantation: Whole blood flow cytometric analysis of lymphocyte function

Despite therapeutic monitoring and daily measurements of blood concentrations (pharmacokinetics) of immunosuppressive medications, immunosuppressive therapy remains still a challenge after heart transplantation (HTx) due to drug interactions, toxicities and individual responses to drug effects. We established whole blood flow cytometric assays of lymphocyte function to assess the pharmacodynamics of immunosuppressive therapy and investigated both pharmacokinetic and pharmacodynamic approaches after HTx. Our results showed that pharmacodynamic measurements provide a more direct assessment of the functional activity of immunosuppressants on immune cells compared to drug level monitoring alone. The information from both pharmacokinetic and pharmacodynamic monitoring has the potential to increase the efficacy and safety of individual immunosuppressive therapy after HTx.

Effect of Mycophenolate Mofetil Monotherapy on T-Cell Functions and Inosine Monophosphate Dehydrogenase Activity in Patients Undergoing a Kidney Transplantation

The aim of this study was to assess the effects of 1 g of mycophenolate mofetil (MMF) on T-cell function and inosine monophosphate dehydrogenase (IMPDH) activity among patients undergoing kidney transplantation. Five patients undergoing renal transplantation from a living donor were enrolled in this study. Compared to baseline (before MMF intake), CD25 and CD71 expression were significantly decreased during the first hour following MMF intake. T-cell proliferation and IMPDH activity also decreased dramatically. Thereafter, all biomarker levels increased over time. At 4 hours, CD25 and CD71 levels, as well as IMPDH activity, returned to almost baseline values, whereas T-cell proliferation remained below baseline. Intracytoplasmic IL-2 expression remained unchanged after MMF ingestions. In conclusion, administration of 1 g of MMF was associated with a transient decrease in CD25 expression in addition to a temporary dramatic decrease in both T-cell proliferation and IMPDH activity.

Leukocyte Suppression is Associated with Improved Clinical Outcomes in Children’s Status after Orthotopic Heart Transplantation

BACKGROUND

Leukocyte suppression is a sequela of immunosuppressive therapy after orthotopic heart transplantation and may result in discontinuation of anti-proliferative agents. Clinical outcomes in this patient population have not been well delineated.

METHODS

This study was a retrospective review of children who underwent orthotopic heart transplantation at our institution from 1986 to 2003. Leukocyte suppression was defined as a white blood cell count <5,000, prompting the withdrawal of anti-proliferative agents. The population was divided into 2 groups, leukosuppressed (LS) and non-leukosuppressed (NLS), and their clinical outcomes were compared.

RESULTS

The study included 109 patients, of which 44 (40%) became leukosuppressed. The 2 groups were similar regarding demographic data and initial management. The LS Group had a significantly decreased incidence of rejection, being 7 times less likely to have recurrent rejection (p = 0.001). The median time to rejection was 0.8 +/- 0.6 years for the NLS Group, whereas the median time to rejection was not yet reached at 17 years for the LS Group. The LS Group also tended toward a decreased incidence of retransplantation or death (p = 0.06). The organ "half-life" in the NLS Group was 7.5 years vs 12.5 years in the LS Group. There was no difference between the 2 groups in regards to other adverse effects of immunosuppression.

CONCLUSIONS

Children who have undergone orthotopic heart transplantation and subsequently become leukosuppressed have a lower incidence of rejection and a tendency toward less organ loss than children who do not become leukosuppressed, without having an increased incidence of adverse side effects.

Combined Use of the JAK3 Inhibitor CP-690,550 with Mycophenolate Mofetil to Prevent Kidney Allograft Rejection in Nonhuman Primates

BACKGROUND

Immunosuppression via Janus kinase (JAK) 3 inhibition affords significant prolongation of allograft survival. We investigated the effects of an immunosuppressive regimen combining the JAK3 inhibitor CP-690,550 with mycophenolate mofetil (MMF) in nonhuman primates (NHPs).

METHODS

Life-supporting kidney transplantations were performed between ABO-compatible, MLR-mismatched NHPs. Animals were treated orally twice a day with CP-690,550 and MMF (n=8) or MMF alone (n=2) and were euthanized at day 90 or earlier due to allograft rejection.

RESULTS

Mean survival time (+/-SEM) in animals treated with MMF alone (23+/-1 days) was significantly extended in animals that concurrently received CP-690,550 (59.5+/-9.8 days, P=0.02). Combination animals exposed to higher levels of CP-690,550 had a significantly better survival (75.2+/-8.7 days) than animals that received less CP-690,550 (33.3+/-12.6 days, P=0.02). Three combination therapy animals were euthanized at day 90 with a subnormal renal function and early-stage acute graft rejection. Rejection, delayed by treatment, ultimately developed in other animals. Anemia and gastrointestinal intolerance was seen in combination therapy animals that otherwise did not show evidence of viral or bacterial infection besides signs consistent with subclinical pyelonephritis (n=3). One incidental lymphosarcoma was noted.

CONCLUSIONS

Addition of CP-690,550 to MMF significantly improved allograft survival. The observed side effects appear amenable to improvements upon alteration of dosing strategies. Efficacy of this combination regimen suggests that it could become the backbone of calcineurin inhibitor-free regimens.

Effects of JAK3 Inhibition with CP-690,550 on Immune Cell Populations and Their Functions in Nonhuman Primate Recipients of Kidney Allografts

BACKGROUND

Janus Kinase (JAK) 3 is a tyrosine kinase essential for proper signal transduction downstream of selected cytokine receptors and for robust T-cell and natural killer cells activation and function. JAK3 inhibition with CP-690,550 prevents acute allograft rejection. To provide further insight into the mechanisms of efficacy, we investigated the immunomodulatory effects of CP-690,550 in vitro and in vivo in nonhuman primates.

METHODS

Pharmacodynamic assessments of lymphocyte activation, function, proliferation and phenotype were performed in three settings: in vitro in whole blood isolated from untransplanted cynomolgus monkeys (cynos), in vivo in blood from untransplanted cynos dosed with CP-690,550 for 8 days, and in vivo in blood from transplanted cynos immunosuppressed with CP-690,550. Cell surface activation markers expression, IL-2- enhanced IFN-gamma production, lymphocyte proliferation and immune cell phenotype analyzes were performed with multiparametric flow cytometry.

RESULTS

In vitro exposure to CP-690,550 resulted in significant reduction of IL-2-enhanced IFN-gamma production by T-cells (maximum inhibition of 55-63%), T-cell surface expression of CD25 (50% inhibitory concentration (IC50); 0.18 microM) and CD71 (IC50; 1.6 microM), and T-cell proliferative capacities measured by proliferating cell nuclear antigen expression (IC50; 0.87 microM). Similar results were observed in animals dosed with CP-690,550. In addition, transplanted animals displayed significant reduction of NK cell (90% from baseline) and T-cell numbers whereas CD8 effector memory T-cell populations were unaffected.

CONCLUSIONS

Potent in vitro and in vivo immunomodulatory effects of the JAK3 inhibitor CP-690,550 likely contribute to its efficacy in the prevention of organ allograft rejection.

Effects of the kinase inhibitor CGP41251 (PKC 412) on lymphocyte activation and TNF-α production

CGP41251 is a serine/threonine and tyrosine kinase inhibitor that is a novel anticancer agent. Because the kinases that CGP41251 inhibits play important roles in T lymphocyte activation, we hypothesized that this compound may have useful immunomodulatory properties. Here we characterized the in vitro immunomodulatory effects of CGP41251. The effects of CGP41251 on lymphocyte proliferation, expression of T cell activation surface markers, and intracellular calcium response in peripheral blood mononuclear cells (PBMC's) were measured. Intracellular IL-2, TNF-alpha, IFN-gamma expression in CGP41251-treated T cells stimulated by lectin was measured by flow cytometry. CGP41251 inhibited lectin-induced lymphocyte proliferation and upregulation of activation surface markers with a 50% inhibitory concentration (IC(50)) of 0.1 microM. CGP41251, at micromolar concentrations, blunted the intracellular calcium response during PBMC activation. CGP41251 inhibited TNF-alpha production by T cells with an IC(50) of 0.5 microM and did not significantly inhibit the production of IL-2 or IFN-gamma. In conclusion, CGP41251 potently inhibits T lymphocyte activation and function and interferes with the proximal part of the T cell activation pathway. The ability of CGP41251 to selectively block T cell TNF-alpha production warrants the evaluation of this compound on other, e.g., monocyte, immune cells and in immunological conditions that are characterized by high TNF-alpha levels such as psoriasis and inflammatory bowel diseases.

Mycophenolic Acid Interaction With Cyclosporine and Tacrolimus In Vitro and In Vivo

The effect of mycophenolic acid (MPA) in combination with either cyclosporine (CsA) or tacrolimus (TRL) on whole-blood lymphocyte function was assessed in vitro as well as in vivo. For the in vitro studies, rat whole blood was incubated with different concentrations of MPA together with CsA or TRL. In vivo, rats (n = 6 per group) were orally treated with 2.5 or 5 mg/kg of mycophenolate mofetil (MMF), either alone or in combination with 5 mg/kg CsA or 4 mg/kg TRL. Blood was obtained before and at different times after dosing. For both in vitro and in vivo studies, mitogen-stimulated whole blood was analyzed by flow cytometry to determine inhibition of expression of lymphocyte proliferation (proliferating cell nuclear antigen, PCNA) and T-cell activation (eg, CD25). Plasma MPA concentrations were measured by HPLC, and whole-blood CsA and TRL concentrations were quantified using LC-MS/MS. In vitro, low concentrations of 250 and 500 nM MPA acted additively with CsA and overadditively with TRL to suppress lymphocyte function, whereas higher MPA concentrations (1000 nM) in these combinations did not further increase inhibition compared with monotherapy with CsA or TRL alone. In vivo, the MPA AUC0-24 showed a dose-dependent increase. CsA and TRL AUC0-24 were not influenced by the MMF dose. Combination therapy increased inhibition of lymphocyte function compared with MMF monotherapy with a pronounced effect on PCNA compared with CD25. Significant differences between 2.5 and 5 mg/kg MMF in the combination groups were observed at 2 or 6 hours after dosing because of the maximal inhibitory effect on PCNA and CD25 expression (P < 0.05, ANOVA). However, in combination with TRL no different effects on the inhibition of CD25 expression were found between the 2 MMF doses. These novel data indicate that measurement of pharmacodynamic parameters of lymphocyte function in whole blood may help to monitor drug combination therapy and provide a rationale for drug reduction to minimize toxicity without compromising efficacy.

Review of the immunosuppressant enteric-coated mycophenolate sodium

Enteric-coated mycophenolate sodium (EC-MPS; myfortic, Novartis Pharma AG) is an advanced formulation delivering mycophenolic acid (MPA). EC-MPS was designed to improve MPA-related upper gastrointestinal adverse events by delaying the release of MPA until reaching the small intestine. At a dose of 720 mg, EC-MPS exhibits equivalent MPA exposure (area under the concentration curve [AUC]) and maximal MPA concentration (C(max)) to mycophenolate mofetil (MMF; CellCept, Roche AG) 1000 mg. The time to maximal MPA concentration (T(max)) for EC-MPS is delayed relative to that for MMF, consistent with a functioning enteric coating. EC-MPS 720 mg b.i.d. has demonstrated therapeutic equivalence to MMF 1000 mg b.i.d. in renal transplant patients. Recent clinical trials have demonstrated that EC-MPS is as effective and safe as MMF in both de novo and maintenance renal transplant patients. Furthermore, studies have confirmed that maintenance patients can be safely converted from MMF to EC-MPS with no compromise of efficacy or safety. EC-MPS therefore presents physicians and patients with a valid alternative MPA therapy with a comparable efficacy and safety profile to MMF.

Immunomodulatory effects of docetaxel on human lymphocytes

Docetaxel is an antineoplastic taxoid that interferes with microtubule polymerization dynamics and is used clinically to treat advanced cancers. Because microtubules play significant roles in T lymphocyte activation and function we characterized the in vitro immunomodulatory properties of docetaxel. Effects of docetaxel on lectin-induced peripheral blood mononuclear cell (PBMC) proliferation were measured by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and proliferating cell nuclear antigen (PCNA) staining. In addition, apoptosis was measured by annexin V staining and cell activation by determination of CD25 and CD71 cell surface expression. Intracellular calcium kinetics in lectin-activated Jurkat T lymphocytes exposed to docetaxel were investigated. Th1 cytokine production was assessed in T lymphocytes by intracellular cytokine staining. Docetaxel significantly inhibited PBMC proliferation and promoted apoptosis of lectin-activated PBMCs. Docetaxel significantly decreased expression of CD71 but not that of CD25. Docetaxel altered intracellular calcium homeostasis but did not affect Th1 cytokine production in T lymphocytes. In conclusion we demonstrate that docetaxel, although exerting significant antiproliferative effects on lymphocytes and promoting activation-induced apoptosis does affect only partially lymphocyte activation and function and does not affect Th1 cytokine production. These results suggest maintenance of lymphocyte functions important for host tumor surveillance and suggest that this compound may have a role in the treatment of cancer arising organ transplant recipients.

Ex vivo lymphocyte proliferative function is severely inhibited in renal transplant patients on mycophenolate mofetil treatment

Mycophenolate mofetil (MMF) is a recently introduced immunosuppressive drug. Its active form is mycophenolic acid (MPA). MPA specifically inhibits de novo purine synthesis, which is vital for T and B lymphocyte proliferation. We measured lymphocyte subset numbers and mitogen induced proliferation in kidney transplant recipients on different combinations of MMF, cyclosporin A (C), azathioprine (A) and prednisolone (P) (C+A n=70; C+A+P n=15; C+MMF n=45; C+MMF+P n=37) and normals (n=73). Patients on MMF had severely reduced phytohaemagglutinin A (PHA) induced proliferation compared to normals (Nml 2766+/-926 CPM/1000 lymphocytes [mean+/-S.D.]; C+MMF 282+/-406; C+MMF+P 195+/-496); non-MMF patients did not differ from normal. Similar inhibition of Poke Weed Mitogen and Staphylococcal enterotoxin B induced proliferation was observed. Cell cycle studies established that MMF patients had a significantly higher proportion of lymphocytes in the G0/G1 phase following PHA stimulation than the non-MMF patients. All transplant groups had significantly lower B cell numbers than the normal controls but no differences in CD4 and CD8 T cell numbers. All but the C+MMF group had significantly lower CD16+NK cell numbers than normal, while only the non-MMF groups had significantly lower CD56+NK cell numbers. The proliferation assay used was an ex vivo diluted whole blood technique. Removal of residual MPA by washing the plasma out prior to mitogen stimulation led to a significant increase in proliferation in six out of seven cases. In summary we have found that MMF treatment has a strikingly inhibitory effect on patient ex vivo lymphocyte mitogenic function.

Development of a high pressure liquid chromatography method for the determination of mycophenolic acid and its glucuronide metabolite in small volumes of plasma from paediatric patients

In order to facilitate the simultaneous determination of the levels of mycophenolic acid (MPA) and mycophenolic acid glucuronide (MPAG) in plasma samples a step wise gradient high performance liquid chromatography (HPLC) method was developed using UV detection system and naproxen as an internal standard. The analytes were extracted from plasma using Strata-X polymeric solid phase extraction (SPE) cartridges. Separation was achieved within a total chromatographic run time of 18 min at 1.0 ml/min flow rate using a Hv PURITY C18 column. The method was found to be linear over the concentration range investigated, 1.0-16 microg/ml (r > 0.99) for MPA and 10-160 microg/ml (r > 0.99) for MPAG. The limit of detection was 0.1 microg/ml for both MPAG and MPA. The intra- and inter-day imprecisions expressed as R.S.D. were 7.8 and 6.6%, respectively, for MPA (1 microg/ml) and 6.2% and 5.6%, respectively, for MPAG (20 microg/ml). The average extraction recovery from plasma was 93.06%, for MPA and 92.41% for MPAG. The method developed was found to be accurate and precise in quantifying the level of MPA and MPAG over a their therapeutic range of concentrations in small volumes of plasma and thus can be effectively used in the routine drug monitoring procedures and pharmacokinetic studies. It was also developed in such a way that it should be easily coupled to an electro-spray ionization mass spectrometer should greater sensitivity be required.

Sustained suppression of peripheral blood immune functions by treatment with mycophenolate mofetil correlates with reduced severity of cardiac allograft rejection

BACKGROUND

We tested the hypothesis that sustained suppression of immune functions by mycophenolate mofetil (MMF) throughout the dosing interval reduces the severity of rejection.

METHODS

Four groups of rat heart allograft recipients were treated orally daily through Day 5 with either: "low-dose" MMF, 10 mg/kg once daily (QD) or 5 mg/kg twice daily (BID); or "high-dose" MMF, 20 mg/kg QD or 10 mg/kg BID. The following were determined for all animals on Day 6: pharmacokinetics (PK, using high-performance liquid chromatography) of mycophenolic acid (MPA); pharmacodynamics (PD, by flow cytometry quantitation of whole blood mitogen-stimulated lymphocyte proliferation and expression of diverse T-cell surface activation molecules); and histologic graft rejection scores (RS).

RESULTS

RS correlated with PD for suppression of both lymphocyte proliferation and transferrin receptor expression (r2 = 0.85 and 0.81, respectively) more highly than with MPA plasma levels (r2 = 0.45), which shows the validity of PD as surrogate markers of MMF efficacy. MMF 5 mg/kg BID produced greater (p < 0.001) suppression of lymphocyte proliferation (area under the PD effect-time curve, AUE = 2,010% inhibition. hour) and sustained trough (E0) PD effect (86% suppression) than MMF 10 mg/kg QD (AUE = 1,436% inhibition. hour, E0 = 55%). RS did not differ between the 20 mg/kg QD and 10 mg/kg BID "high-dose" groups, because PD was maximally suppressed.

CONCLUSIONS

PD were surrogate markers for MMF immunosuppressive efficacy. MMF 5 mg/kg BID produced more sustained suppression of both PD and rejection than MMF 10 mg/kg QD.

Assessment of immunosuppressive drug interactions: inhibition of lymphocyte function in peripheral human blood

Cyclosporin (CsA) or tacrolimus (TRL) is routinely combined with either sirolimus (SRL) or mycophenolate mofetil (MMF) in immunosuppressive regimes in organ transplantation. The aim of our study was to establish a specific human blood assay of lymphocyte function in order to assess interactions of these drug combinations. Different concentrations (10(6)-10(9) nM) of CsA, TRL, SRL or mycophenolic acid (MPA, the active metabolite of MMF) was added to whole blood of five human volunteers. Drug combinations were studied by adding 250, 500 or 1000 nM of MPA to different concentrations of CsA, TRL, or SRL or by adding 1, 10 or 25 nM of SRL to different concentrations of CsA or TRL. After concanavalin-A stimulation, whole blood cultures were analyzed by flow cytometry detecting lymphocyte proliferation and activation by bivariate expression of proliferating cell nuclear antigen (PCNA)/DNA content and T cell-surface activation antigens (e.g. CD25, CD95, and CD154). We found an order of potency inhibiting lymphocyte function with SRL>TRL>CsA>MPA. In addition, we observed enhanced inhibition of PCNA, CD25, CD95 or CD154, if either CsA or TRL was combined with low concentrations of MPA, or SRL alone or if SRL was combined with low concentrations of MPA. Data analysis revealed an independent functional synergism or partial agonism in most combinations. This human blood assay is able to assess lymphocyte function and to monitor immunosuppressive therapy. The assay also permits pharmacological analysis of drug interactions, which will lead to improved safety and therapeutic efficacy in transplanted patients.

Mycophenolate Mofetil in Multiple Sclerosis

OBJECTIVE

To describe experience with the use of mycophenolate mofetil (MMF) in the treatment of multiple sclerosis (MS).

BACKGROUND

MMF is a potent immunosuppressant that is a selective inhibitor of inosine 5'-monophosphate dehydrogenase type II, the enzyme responsible for the de novo synthesis of the purine nucleotide guanine within activated T and B lymphocytes and macrophages.

METHODS

A retrospective review of experience in treating 79 MS patients with MMF (61 with secondary progressive, 14 with relapsing-remitting, and 4 with primary progressive MS) in the authors' MS center.

RESULTS

In most cases, MMF was added as adjunctive therapy in patients already being treated with either interferon-beta (n = 44) or glatiramer acetate (n = 20). Fifteen patients not able to use interferon or glatiramer acetate were treated with MMF monotherapy. Seventy percent of the patients continued MMF therapy. Eight patients discontinued therapy because of side effects, 7 patients continued to exhibit evidence of disease progression, 4 were denied insurance coverage, 2 were lost to follow-up, and 1 patient had an elevation of hepatic transaminases that resolved on discontinuation of MMF. One patient discontinued MMF therapy secondary to cytomegalovirus diarrhea.

CONCLUSION

MMF was well tolerated by the majority of patients treated. While these clinical observations were uncontrolled, the clinical course of MS was either unchanged or subjectively improved in many of the treated patients. A randomized controlled trial of MMF in MS, either as monotherapy or in conjunction with interferon or glatiramer acetate, appears warranted.

Pharmacodynamics of mycophenolate mofetil after heart transplantation: new mechanisms of action and correlations with histologic severity of graft rejection

The primary mechanism of action in vivo of mycophenolate mofetil (MMF) is believed to be inhibition of lymphocyte proliferation. We used novel assays of lymphocyte functions (pharmacodynamics, PD) in whole blood collected from rat heart allograft recipients treated with MMF to investigate the mechanisms of action of the active metabolite of MMF, mycophenolate acid (MPA) in vivo. Allograft recipients were treated orally once daily with 3 different doses of MMF. Seven days after transplantation, blood was collected 24h after the penultimate dose and several timepoints after the last dose, after which grafts were removed for microscopic grading of rejection. Lymphocytes in whole blood samples were mitogen stimulated through calcium-dependent and -independent signaling pathways. Inhibition of PD was measured by lymphocyte proliferation and expression of several surface antigens on T cells, and was calculated as area under the time-inhibition of immune function effect curve (AUE0-24h). We found that inhibition of lymphocyte proliferation and antigen expression by MPA correlated highly with MMF-dose, MPA level and with the histologic severities of graft rejection (p <0.05). In summary, MPA suppressed lymphocyte proliferation and expression of T-cell surface antigens in whole blood collected from MMF-treated allograft recipients, thus demonstrating the multiple mechanisms of suppression of rejection on peripheral blood T cells after MMF treatment.