Pharmacokinetics, pharmacodynamics, and immunodynamics of daclizumab in a two-dose regimen in liver transplantation

Design, creation and in vitro testing of a reduced immunogenicity humanized anti-CD25 monoclonal antibody that retains functional activity

Humanized and fully human sequence-derived therapeutic antibodies retain the capacity to induce anti-drug antibodies. Daclizumab (humanized version of the murine anti-Tac antibody; E.HAT) was selected for a proof of concept application of engineering approaches to reduce potential immunogenicity due to its demonstrated immunogenicity in the clinic. Reduced immunogenicity variants of E.HAT were created by identifying and modifying a CD4+ T cell epitope region in the VH region. Variant epitope region peptides were selected for their reduced capacity to induce CD4+ T cell proliferative responses in vitro. Variant antibody molecules were created, and CD25 affinity and potency were similar to the unmodified parent antibody. Fab fragments from the variant antibodies induced a lower frequency and magnitude of responses in human peripheral blood mononuclear cells proliferation tests. By the empirical selection of two amino acid mutations, fully functional humanized E.HAT antibodies with reduced potential to induce immune responses in vitro were created.

Frontiers of monoclonal antibodies: Applications in medical practices

With the flourishing of innovation in drug discovery into a new era of personalized therapy, the use of monoclonal antibodies (mAbs) in the treatment of various ailments lies at the forefront. Major improvements in genetic sequencing and biomedical techniques as well as research into mAbs emphasize on determining new targets for advanced therapy while maximizing efficacy for clinical application. However, a balance has to be achieved concerning developing a target with low toxicity combined with high specificity and versatility, to allow a specific antibody to facilitate several biotic effects, ranging from neutralization of virus mechanisms to modulation of immune response and maintaining low global economic cost. Presently, there are approximately 30 mAbs' permitted for therapeutic use with many more being tested in clinical trials. Nevertheless, the heavy cost of mAbs' production, stowage and management as well as the subsequent hindrances to their development are outweighed by mAbs' clinical advantages. Compared to conventional drugs, since mAbs use as pharmacologic iotas have specific physical features and modes of action, they should be considered as a discrete therapeutic category. In this review, the history of mAb generation and the innovative technological applications of mAbs that has advanced in clinical practices is reviewed.

Acute and Chronic Rejection After Liver Transplantation: What A Clinician Needs to Know

While antibody mediated hyper-acute vasculitic rejection is rare in liver transplant recipients, acute and chronic rejection have clinical significance. The liver allograft behaves differently to other solid organ transplants as acute rejection generally does not impair graft survival and chronic rejection (CR) is uncommon. The incidence of acute and chronic rejection has declined in current era due to improved immunosuppressive regimens. Acute rejection generally improves with steroid boluses and steroid resistant rejection is uncommon. CR may improve with escalation of immunosuppression or may result in irreversible loss of graft function leading to retransplantation or death. The current review discusses diagnosis and management of acute and chronic liver allograft rejection.

Antibody induction versus corticosteroid induction for liver transplant recipients

BACKGROUND

Liver transplantation is an established treatment option for end-stage liver failure. To date, no consensus has been reached on the use of immunosuppressive T-cell specific antibody induction compared with corticosteroid induction of immunosuppression after liver transplantation.

OBJECTIVES

To assess the benefits and harms of T-cell specific antibody induction versus corticosteroid induction for prevention of acute rejection in liver transplant recipients.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Science Citation Index Expanded, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) on 30 September 2013 together with reference checking, citation searching, contact with trial authors and pharmaceutical companies to identify additional trials.

SELECTION CRITERIA

We included all randomised clinical trials assessing immunosuppression with T-cell specific antibody induction versus corticosteroid induction in liver transplant recipients. Our inclusion criteria stated that participants within each included trial should have received the same maintenance immunosuppressive therapy.

DATA COLLECTION AND ANALYSIS

We used RevMan for statistical analysis of dichotomous data with risk ratio (RR) and of continuous data with mean difference (MD), both with 95% confidence intervals (CIs). We assessed risk of systematic errors (bias) using bias risk domains with definitions. We used trial sequential analysis to control for random errors (play of chance).

MAIN RESULTS

We included 10 randomised trials with a total of 1589 liver transplant recipients, which studied the use of T-cell specific antibody induction versus corticosteroid induction. All trials were with high risk of bias. We compared any kind of T-cell specific antibody induction versus corticosteroid induction in 10 trials with 1589 participants, including interleukin-2 receptor antagonist induction versus corticosteroid induction in nine trials with 1470 participants, and polyclonal T-cell specific antibody induction versus corticosteroid induction in one trial with 119 participants.Our analyses showed no significant differences regarding mortality (RR 1.01, 95% CI 0.72 to 1.43), graft loss (RR 1.12, 95% CI 0.82 to 1.53) and acute rejection (RR 0.84, 95% CI 0.70 to 1.00), infection (RR 0.96, 95% CI 0.85 to 1.09), hepatitis C virus recurrence (RR 0.89, 95% CI 0.79 to 1.00), malignancy (RR 0.59, 95% CI 0.13 to 2.73), and post-transplantation lymphoproliferative disorder (RR 1.00, 95% CI 0.07 to 15.38) when any kind of T-cell specific antibody induction was compared with corticosteroid induction (all low-quality evidence). Cytomegalovirus infection was less frequent in patients receiving any kind of T-cell specific antibody induction compared with corticosteroid induction (RR 0.50, 95% CI 0.33 to 0.75; low-quality evidence). This was also observed when interleukin-2 receptor antagonist induction was compared with corticosteroid induction (RR 0.55, 95% CI 0.37 to 0.83; low-quality evidence), and when polyclonal T-cell specific antibody induction was compared with corticosteroid induction (RR 0.21, 95% CI 0.06 to 0.70; low-quality evidence). However, when trial sequential analysis regarding cytomegalovirus infection was applied, the required information size was not reached. Furthermore, diabetes mellitus occurred less frequently when T-cell specific antibody induction was compared with corticosteroid induction (RR 0.45, 95% CI 0.34 to 0.60; low-quality evidence), when interleukin-2 receptor antagonist induction was compared with corticosteroid induction (RR 0.45, 95% CI 0.35 to 0.61; low-quality evidence), and when polyclonal T-cell specific antibody induction was compared with corticosteroid induction (RR 0.12, 95% CI 0.02 to 0.95; low-quality evidence). When trial sequential analysis was applied, the trial sequential monitoring boundary for benefit was crossed. We found no subgroup differences for type of interleukin-2 receptor antagonist (basiliximab versus daclizumab). Four trials reported on adverse events. However, no differences between trial groups were noted. Limited data were available for meta-analysis on drug-specific adverse events such as haematological adverse events for antithymocyte globulin. No data were available on quality of life.

AUTHORS' CONCLUSIONS

Because of the low quality of the evidence, the effects of T-cell antibody induction remain uncertain. T-cell specific antibody induction seems to reduce diabetes mellitus and may reduce cytomegalovirus infection when compared with corticosteroid induction. No other clear benefits or harms were associated with the use of T-cell specific antibody induction compared with corticosteroid induction. For some analyses, the number of trials investigating the use of T-cell specific antibody induction after liver transplantation is small, and the numbers of participants and outcomes in these randomised trials are limited. Furthermore, the included trials are heterogeneous in nature and have applied different types of T-cell specific antibody induction therapy. All trials were at high risk of bias. Hence, additional randomised clinical trials are needed to assess the benefits and harms of T-cell specific antibody induction compared with corticosteroid induction for liver transplant recipients. Such trials ought to be conducted with low risks of systematic error and of random error.

Pharmacokinetics, pharmacodynamics and physiologically-based pharmacokinetic modelling of monoclonal antibodies

Development of monoclonal antibodies (mAbs) and their functional derivatives represents a growing segment of the development pipeline in the pharmaceutical industry. More than 25 mAbs and derivatives have been approved for a variety of therapeutic applications. In addition, around 500 mAbs and derivatives are currently in different stages of development. mAbs are considered to be large molecule therapeutics (in general, they are 2-3 orders of magnitude larger than small chemical molecule therapeutics), but they are not just big chemicals. These compounds demonstrate much more complex pharmacokinetic and pharmacodynamic behaviour than small molecules. Because of their large size and relatively poor membrane permeability and instability in the conditions of the gastrointestinal tract, parenteral administration is the most usual route of administration. The rate and extent of mAb distribution is very slow and depends on extravasation in tissue, distribution within the particular tissue, and degradation. Elimination primarily happens via catabolism to peptides and amino acids. Although not definitive, work has been published to define the human tissues mainly involved in the elimination of mAbs, and it seems that many cells throughout the body are involved. mAbs can be targeted against many soluble or membrane-bound targets, thus these compounds may act by a variety of mechanisms to achieve their pharmacological effect. mAbs targeting soluble antigen generally exhibit linear elimination, whereas those targeting membrane-bound antigen often exhibit non-linear elimination, mainly due to target-mediated drug disposition (TMDD). The high-affinity interaction of mAbs and their derivatives with the pharmacological target can often result in non-linear pharmacokinetics. Because of species differences (particularly due to differences in target affinity and abundance) in the pharmacokinetics and pharmacodynamics of mAbs, pharmacokinetic/pharmacodynamic modelling of mAbs has been used routinely to expedite the development of mAbs and their derivatives and has been utilized to help in the selection of appropriate dose regimens. Although modelling approaches have helped to explain variability in both pharmacokinetic and pharmacodynamic properties of these drugs, there is a clear need for more complex models to improve understanding of pharmacokinetic processes and pharmacodynamic interactions of mAbs with the immune system. There are different approaches applied to physiologically based pharmacokinetic (PBPK) modelling of mAbs and important differences between the models developed. Some key additional features that need to be accounted for in PBPK models of mAbs are neonatal Fc receptor (FcRn; an important salvage mechanism for antibodies) binding, TMDD and lymph flow. Several models have been described incorporating some or all of these features and the use of PBPK models are expected to expand over the next few years.

FoxP3+, and not CD25+, T cells increase post-transplant in islet allotransplant recipients following anti-CD25+ rATG immunotherapy

Anti-CD25 antibodies are used as an induction therapy in islet allotransplantation for type 1 diabetes. Although previous reports suggested that anti-CD25 treatment may lead to depletion of CD4+CD25+ regulatory T cells (Tregs) and questioned its use in tolerance-promoting protocols for transplantation, the effect of anti-CD25 antibodies on the frequency and function of Tregs remains unclear. We examined the effect of anti-CD25 antibody, daclizumab, in vivo on Tregs in islet allograft recipients enrolled in a single-center study and monitored post-transplant. Our data shows that the reduction in CD25+ Treg cells observed post-transplant is due to masking of CD25 receptor by daclizumab and not due to depletion. In addition, using Treg marker, FoxP3, we show that anti-CD25+ ATG treatment leads to an increase in FoxP3+ Tregs post-transplant. These data suggest that anti-CD25-based therapy has beneficial effects on Tregs and combined with ATG may be a promising therapy for autoimmunity and transplantation.

Antibody immunosuppressive therapy in solid-organ transplant: Part I

Currently, a wide variety of both polyclonal and monoclonal antibodies are being routinely utilized to prevent and treat solid organ rejection. More commonly, these agents are also administered in order to delay introduction of calcineurin inhibitors, especially in patients with already compromised renal function. While these antibody therapies dramatically reduced the incidence of acute rejection episodes and improved both short and long-term graft survival, they are also associated with an increased incidence of opportunistic infections and neoplastic complications. Therefore, effective patient management must necessarily balance these risks against the potential benefits of the therapy.

Innovative monoclonal antibody therapies in multiple sclerosis

The recent years have witnessed great efforts in establishing new therapeutic options for multiple sclerosis (MS), especially for relapsing-remitting disease courses. In particular, the application of monoclonal antibodies provide innovative approaches allowing for blocking or depleting specific molecular targets, which are of interest in the pathogenesis of MS. While natalizumab received approval by the US Food and Drug Administration and the European Medicines Agency in 2006 as the first monoclonal antibody in MS therapy, rituximab, alemtuzumab, and daclizumab were successfully tested for relapsing-remitting MS in small cohorts in the meantime. Here, we review the data available from these recent phase II trials and at the same time critically discuss possible pitfalls which may be relevant for clinical practice. The results of these studies may not only broaden our therapeutic options in the near future, but also provide new insights into disease pathogenesis.

Daclizumab induction therapy in liver transplant recipients with renal insufficiency

BACKGROUND

The role of interleukin 2 (IL-2) receptor antibodies to avoid the nephrotoxic effects of calcineurin inhibitors in the early post-liver transplant (LT) period is not well defined.

AIM

To examine the use of daclizumab induction in LT recipients with renal insufficiency.

METHODS

Between 2002 and 2005, 62 patients (median pre-LT creatinine 2.4 mg/dL, IQR 1.9-3.7) received daclizumab induction with tacrolimus being administered when serum creatinine was <2.0 mg/dL. A concurrent comparison group (n = 221, 2002-2005) received tacrolimus-based immunosuppression without daclizumab (median pre-LT creatinine 1.1 mg/dL, IQR 0.9-1.4). A second historical comparison group (n = 103, 1995-2005) not receiving daclizumab was matched to the daclizumab patients by pre-LT serum creatinine (2.2 mg/dL, IQR 1.8-3.1). All patients received mycophenolate mofetil and steroids.

RESULTS

Serum creatinine improved in the daclizumab group (-1.0 mg/dL, IQR -2.2 to -0.4) and worsened in the concurrent comparison group (+0.2 mg/dL, IQR 0-0.5) from pre-LT to 4 months. However, there was no difference when daclizumab group was compared with the historical comparison group matched on pre-LT creatinine (median change: -0.8 mg/dL vs. -0.7 mg/dL). Daclizumab induction was not associated with improvement in renal function at 4 months (P = 0.34) after adjusting for pre-LT creatinine, age, gender, hepatitis C status and simultaneous liver kidney transplantation.

CONCLUSION

The incremental benefit offered by induction therapy with IL-2 receptor antibodies to preserve renal function is questionable.

Interleukin-2 receptor blockade with humanized monoclonal antibody for solid organ transplantation

IMPORTANCE OF THE FIELD

Induction therapy has reduced the incidence of acute rejection compared with historical standards. The potency of currently available induction immunosuppression is not without risk and should be carefully considered. Induction with daclizumab, an IL-2 receptor antagonist, has been used safely and effectively for over 10 years across different transplant types. As a result of daclizumab use, transplant centers are able to implement steroid-sparing or calcineurin minimization protocols. Unfortunately, the manufacturing costs have resulted in withdrawal of this agent from the market reducing the options for patients undergoing transplantation.

AREAS COVERED IN THIS REVIEW

This review will update the reader on recently published daclizumab studies in adult solid organ transplant recipients, focusing on comparative studies with other induction agents.

WHAT THE READER WILL GAIN

This paper will provide a summary of comparative studies between daclizumab and other induction therapies focusing on their efficacy and safety.

TAKE HOME MESSAGE

Novel applications, such as long-term use in combination with calcineurin-inhibitor dose reduction and its value in the treatment of acute or chronic rejection have yet to be explored. Since daclizumab has been withdrawn from the market, future IL-2 receptor blockade will have to be achieved with basiliximab, which is a chimeric, monoclonal antibody directed against the same epitope.

Two doses of humanized anti-CD25 antibody in renal transplantation: a preliminary comparative study

HuCD25mAb is a humanized anti-CD25 antibody which has the same amino acid sequence as daclizumab (Zenapax, Roche). HuCD25mAb is expressed in Chinese hamster ovary (CHO) cells while daclizumab is expressed in the NSO myeloma cell line. A comparative study was performed to evaluate the pharmacokinetics and pharmacodynamics between huCD25mAb and daclizumab in a two-dose regimen incorporating triple immunosuppressant treatment regimens (MMF, CsA and steroids). Fifteen patients were enrolled and randomized to receive intravenous infusion of either huCD25mAb (n = 10) or daclizumab (n = 5) at a dosage of 1 mg.kg(-1) on operation day 0 and post-operation day 14. Serum concentrations of huCD25mAb and daclizumab were measured by a validated competitive ELISA. Subgroups of CD3(+), CD25(+), CD4(+) and CD8(+) lymphocytes were monitored periodically by flow cytometry. The concentration-time curves of huCD25mAb and daclizumab were found to fit well to a one-compartment model. A significant decline of proportion (%) of CD3-CD25(+) and CD3(+)CD25(+) lymphocytes was observed 30 min after first infusion on day 0 (3.40 +/- 1.83 to 0.03 +/- 0.07, 3.35 +/- 2.02 to 0.37 +/- 0.49), and these levels remained low for at least 70 days (0.03 +/- 0.05, 0.31 +/- 0.47). All pharmacokinetic parameters of huCD25mAb seemed similar to those of daclizumab. The two-dose huCD25mAb regimen was as effective as daclizumab in rapidly achieving high therapeutic concentration in the treated patients, and a significant decrease of CD3(-)CD25(+) and CD3(+)CD25(+) lymphocytes was demonstrated. This suggests that two-dose regimen is feasible in maintaining host immunosuppression and may provide an effective and economical strategy for reducing incidence of acute graft rejection.

Specific antibodies induced by DNA vaccination with extracellular domain of CD25 gene protect against ConA-induced autoimmune hepatitis

Antibodies to CD25 (anti-CD25) were used clinically to achieve immunosuppression in autoimmune disease, while the possibility of anti-antibodies generation influenced its efficiency. Here we reported that DNA vaccine encoding the extracellular domain of murine CD25 gene (pCD25-ECD) elicited anti-CD25 antibody production in BALB/c mice and subsequently prevents the host against ConA-induced autoimmune hepatitis. We found that serum CD25-specific antibodies were generated after vaccination with pCD25-ECD. Moreover, high levels of IL-4, IL-10 and anti-CD25 antibody were produced by splenocytes of vaccinated mice after CD25 protein restimulation in vitro. Furthermore, we demonstrated that the vaccinated mice suffered less from liver injury induced by ConA, accompanied by the reduction of pathogenic CD4+ T cells. Finally, we showed that the immunized serum could cause cytolysis of activated CD4+ T cells in vitro, depending on complements activation. Our study showed pCD25-ECD induced self anti-CD25 antibodies which executed immunosuppression in autoimmune hepatitis via antibody-complement pathway.

Monoclonal antibodies in the therapy of multiple sclerosis: an overview

With the generation of monoclonal antibodies (mAbs), a new therapeutical concept has gained importance. MAbs aim against selective antigens and so have changed our treatment strategies from non-specific to specific. Four therapeuticals have gained importance in the therapy of multiple sclerosis (MS): One has already been approved for therapy (natalizumab), whereas the other three are either in clinical trials or are about to enter phase III studies. Currently, two phase III studies that evaluate the efficacy of alemtuzumab have begun with recruitment (MS CARE I and II). Another mAb (daclizumab) under study is directed to the interleukin-2alpha chain (CD25). Results of clinical trials are promising by reporting reduction of relapses and progression in relapsing remitting and secondary progressive MS accompanied by reduction of new lesions in magnetic resonance imaging. A multicenter randomized controlled trial of daclizumab in MS is going to be initiated. Trials with a humanised antibody directed against the cell surface molecule CD20 are under development. Although the future will emphasise this trend to mAbs, the risks should not be ignored as has been shown in recent news. Still, mAbs have the possibility to revolutionise therapeutical concepts in the treatment of immune-mediated diseases, and will therefore be a useful addition to current therapeutic concepts.

Interleukin-2 in CD8+ T cells correlates with Banff score during organ rejection in liver transplant recipients

The aim of this study is to compare the histological grading of acute organ rejection according to the Banff score with intracellular interleukin-2 (IL-2) concentrations in cytotoxic CD8+ T cells from peripheral blood samples. 66 recipients after liver transplantation and 20 healthy controls were included into this study. Blood samples of liver transplant recipients were collected beside routine visits or, in case of suspected organ rejection, with additional liver biopsy. For cytometry, the blood cells were stained with CD3, CD8 and intracellular-IL-2. The percentage of cells with detectable intracellular IL-2 was significantly increased in patients with acute rejection (n = 7, P < 0.001, t Test) compared to recipients without rejection. The percentage of cells with detectable intracellular IL-2 (mean +/- SEM) was 7.6 +/- 0.9% in rejection patients, 2.3 +/- 0.22% in stable liver transplant recipients, and 14 +/- 2.99% in healthy controls. Intracellular IL-2 correlates to the Banff score in rejection patients (Spearmans-rho = 0.81, P < 0.05). This cytometric method shows a good sensitivity (71%) with a cut-off based on a high specificity of 95% for histological proven organ rejection in our study cohort. Measurement of intracellular IL-2 in cytotoxic CD8+ T-lymphocytes by flow cytometry correlates very well to the histological grading according to the Banff score and shows a good sensitivity and excellent specificity in acute organ rejection.

Following-up of a four-dose daclizumab induction therapy without calcineurin inhibitors in a liver transplantation recipient with severe renal dysfunction: a case report

BACKGROUND

There is debate on the dose schedule and pharmacokinetics of daclizumab in liver transplant recipients.

METHODS

A four-dose course of daclizumab was administered to a patient with severe renal dysfunction. Calcineurin inhibitor therapy initiation was delayed to 86 days posttransplantation.

RESULTS

The patient is well as 480 days after transplantation. No rejection was observed.

CONCLUSIONS

The result suggested the efficacy of our dose schedule, but it will be necessary to confirm it with further pharmacokinetic studies and more cases.

Pharmacokinetics and immunodynamics of basiliximab in pediatric renal transplant recipients on mycophenolate mofetil comedication

BACKGROUND

The aim of this substudy within a prospective, multicenter, placebo-controlled trial was to assess the pharmacokinetics and immunodynamics of basiliximab in pediatric renal transplant recipients on comedication with mycophenolate mofetil (MMF).

METHODS

Eighty-two patients aged 3 to 18 years, receiving cyclosporine microemulsion, MMF, corticosteroids, and basiliximab or placebo were investigated. Basiliximab serum concentrations were determined by ELISA, CD25+, and CD122+ T lymphocytes by flow cytometry.

RESULTS

Basiliximab clearance adjusted to body surface area was significantly (P<0.05) greater in children versus adults, but the relatively higher basiliximab dose given to children yielded similar exposure compared with adolescents. A cross-study comparison revealed that MMF reduced basiliximab clearance and prolonged CD25 saturation duration from approximately 5 weeks in the absence of MMF to 10 weeks in the presence of MMF. Basiliximab led to a marked reduction of CD25+ T-cell fraction during the first 8 to 10 weeks posttransplant, but did not specifically affect CD122+ T cells. The majority of biopsy-proven acute rejection episodes (BPAR) were observed after interleukin (IL) 2-R desaturation, whereas about a quarter of BPARs occurred despite adequate IL2-R blockade.

CONCLUSIONS

The currently recommended basiliximab dose for pediatric patients, when used with cyclosporine microemulsion and corticosteroids, yielded adequate drug exposure in children and adolescents also under MMF comedication. The observation that about a quarter of BPARs occurred despite adequate IL2-R blockade suggests that another T-cell activation pathway independent of the IL-2/IL-2R pathway is operative, for example, the IL-15 signaling pathway.

Identification and development of new therapeutics for multiple sclerosis

In recent years, large efforts have been undertaken to establish new therapeutic options for the treatment of multiple sclerosis (MS). So far, all of these strategies more or less specifically target subsets of the immune response in MS, including not only activation and expansion of T cells, their circulation and transmigration over the blood-brain barrier but also other cell types such as B cells and probably also natural killer cells. Here, we review available data on the most promising (at present) new therapeutic approaches. These involve the orally available compounds cladribine, FTY720, fumaric-acid esters, laquinimod and teriflunomide in addition to the monoclonal antibodies alemtuzumab, daclizumab, natalizumab and rituximab. After successful completion of Phase III studies, these compounds might have the potential to add to the current therapeutic armentarium especially for relapsing remitting disease courses in the near future, possibly opening the way to a more individualized treatment.

Daclizumab

Daclizumab is a humanized monoclonal antibody which binds to the IL-2 receptor on activated lymphocytes and blocks the production of IL-2. Its use is well established in solid organ transplantation as induction therapy, especially in high-risk patients where reduction or delayed dose of standard immunosuppression would be beneficial. It has been used effectively in both 2-dose and 5-dose regimens in conjunction with other standard immunosuppressive agents. The incidence of acute rejection appears reduced without increasing the rates of infection or post-transplant lympho-proliferative disorders. The agent is generally well tolerated in adults and children and there is no need for additional monitoring. Daclizumab has also been used outside the transplant arena in a variety of immune-mediated diseases with limited success.

Emerging monoclonal antibody therapies for multiple sclerosis

BACKGROUND

Monoclonal antibodies constitute a relatively new class of therapeutic agent designed to interact with specific target antigens. Monoclonal antibodies can be created to deplete cell lineages or antagonize receptors for which small molecule drugs are not available. Because of their accessibility, proteins expressed on the surface of immune system cell lineages are appealing targets for monoclonal antibody therapies.

REVIEW SUMMARY

To review monoclonal antibodies currently under investigation for treatment of multiple sclerosis (MS). This was a review of the literature and ongoing clinical trials. Alemtuzumab, daclizumab, rituximab, and natalizumab are monoclonal antibodies at different stages of clinical development that show promise as MS disease modifying therapies.

CONCLUSIONS

Several monoclonal antibodies directed against antigens present on the cell surface of immune system cell lines are promising candidates for immune suppression therapies in MS. Because these drugs are still in development, their clinical benefits and safety profiles are not fully established. Nevertheless, it seems possible that their specificity will offer advantages over broad-spectrum immune suppressing therapies.

A prospective, randomized, multicenter study evaluating the safety and efficacy of two dosing regimens of daclizumab compared to no antibody induction in simultaneous kidney-pancreas transplantation: results at 3 years

This is a report of outcomes at 36 months of a prospective, multicenter study comparing the safety and efficacy of two dosing regimens of daclizumab with no antibody induction in simultaneous kidney-pancreas transplant (SKPT) patients receiving tacrolimus, mycophenolate mofetil, and prednisone. A total of 298 SKPT patients were randomized into one of three groups: daclizumab 1 mg/kg/dose every 14 days for 5 doses (group 1, n = 107); daclizumab 2 mg/kg/dose for 2 doses (group 2, n = 113); and no antibody induction (group 3, n = 78). There were no differences in baseline characteristics among the three groups, and results were analyzed by an intent-to-treat analysis. The incidence of composite events (acute rejection [AR], any allograft lost, or death) at 3 years was 49%, 43%, and 55% in groups 1, 2, and 3, respectively (P = .278). The cumulative incidences of AR were not statistically different among the three groups (P = .178). The mean time to first AR was delayed in groups 2 (288 days) and 1 (245 days) compared to group 3 (145 days, P = .07). There were no differences in patient or allograft survival rates among the three groups, and the rates of serious adverse events, infections, and hospital readmissions were also comparable. Excellent dual graft function in patients with surviving grafts was observed in all three groups at 3 years.

CONCLUSIONS

The alternative 2-dose regimen of daclizumab was as safe and effective as the conventional 5-dose regimen compared to no antibody induction in SKPT patients, but no long-term benefits were noted.

A novel three-dose regimen of daclizumab in liver transplant recipients with hepatitis C: a pharmacokinetic and pharmacodynamic study

This study evaluated the pharmacokinetics and pharmacodynamics of a novel 3-dose regimen of daclizumab in de novo hepatitis C liver transplant recipients. In 30 of 156 recipients receiving daclizumab, mycophenolate mofetil, tacrolimus, and no steroids (Arm 3 of Hep C 3 Liver Study), daclizumab (2, 2, and 1 mg/kg, respectively) was given on days 1, 3, and 8 posttransplant, respectively, with trough, peak (C(max)), and CD25 saturation (CD(sat)) measured sequentially. Mean daclizumab C(max) was 50.3 microg/mL on day 1, and mean trough levels were 21.8, 25.7, and 9.9 microg/mL on days 3, 8, and 30, respectively. A significant decline in CD(sat) (mean, 15.7% to 4.7%) was observed on day 1 and was sustained throughout the study (2.8% on day 30). Daclizumab concentration > or = 5 microg/mL was the level where most of the effect on CD(sat) was noticed. Elevated baseline CD(sat) was observed in African Americans, patients weighing < or = 75 kg, and patients <60 years of age. After 365 days, 2 patients had experienced 3 rejections, 10 patients had recurrent hepatitis C, 4 patients died, and 2 grafts were lost. In conclusion, this novel 3-dose regimen is effective in rapidly achieving high therapeutic concentration of daclizumab and a significant decline in CD(sat) lasting over 30 days.

Anti-interleukin 2 receptor antibodies and mycophenolate mofetil for treatment of steroid-resistant rejection in adult liver transplantation

BACKGROUND

Steroid-resistant rejection (SRR) results in significant morbidity and mortality from the adverse effects of rescue therapy and in graft loss from chronic rejection. In our knowledge, the efficacy and safety of anti-interleukin (IL) 2r antibodies (daclizumab and basiliximab) for the treatment of SRR in adult liver transplantation has not previously been evaluated.

METHODS

Twenty-five patients received either daclizumab or basiliximab as rescue therapy for SRR. Outcome and biochemical parameters were recorded before and after treatment with an anti-IL-2r antibody.

RESULTS

The median time from transplantation to SRR was 25 days. Secondary immunosuppression included mycophenolate mofetil in 18 patients. Twelve patients (48%) had complete resolution of SRR. Aspartate transaminase levels normalized at a median of 37 days (range, 1-168 days). In 13 patients (52%) progressive hepatic dysfunction developed. Four of these patients received another transplant, and 6 patients had chronic rejection. Three patients died with graft failure. Of 16 patients with acute cellular rejection, 12 (75%) had resolution, 2 had chronic rejection, 1 required a repeat transplantation, and 1 died with graft failure. In contrast, all 9 patients with established chronic rejection in their pretreatment biopsy continued to have significant graft dysfunction, with 4 having persistent chronic graft dysfunction, 3 requiring repeat transplantation, and 2 dying with graft failure.

CONCLUSION

Twelve (48%) of 25 patients who received an anti-IL-2r antibody because of SRR were successfully treated. All successfully treated patients had ongoing acute cellular rejection at liver biopsy (75%), whereas patients with histologic evidence of chronic rejection responded poorly.

Risk Factors and Outcomes Analyses at 36 Months of a Prospective, Randomized, Multicenter, Trial of Daclizumab Induction in Simultaneous Kidney–Pancreas Transplant Recipients

The purpose of this study was to analyze risk factors for acute rejection (AR) and long-term outcomes in simultaneous kidney-pancreas transplant (SKPT) patients enrolled in a prospective, multicenter study of daclizumab (DAC) versus no antibody induction.

METHODS

A total of 298 SKPT patients were randomized into three groups and categorized based on an intent to treat analysis, and factors associated with AR and survival were identified using logistic regression and Cox proportional hazards models.

RESULTS

There were no differences in patient or allograft survival or rejection rates among the three groups at 36 months follow-up. Delayed (kidney) graft function (DGF) was a risk factor for subsequent kidney AR (odds ratio = 2.79, P = .002). The presence of kidney AR was also a risk factor (hazard ratio [HR] = 3.1, P = .003) for kidney graft loss, whereas risk factors for pancreas graft loss (censored for graft loss within 30 days or death with functioning graft) included pancreas AR (HR = 1.97, P = .012), kidney AR (HR = 1.61, P = .042), CMV serostatus donor +/recipient - (HR = 1.62, P = .026), and HLA-B mismatch (HR = 1.58, P = .01). Kidney graft loss (HR = 5.5, P = .02) was the only predictor of mortality.

CONCLUSIONS

At 36 months, no significant differences in outcomes were noted in the three study groups. DGF was the major risk factor for kidney AR, kidney AR was the major risk factor for kidney graft loss, and kidney graft loss was the major determinant of mortality. Prevention of kidney DGF and AR in SKPT recipients may play a pivotal role in optimizing long-term outcomes.

Antibody induction therapy in renal transplant patients receiving calcineurin-inhibitor immunosuppressive regimens: a comparative review

Acute rejection during the first year post-transplant is a key predictor of graft survival after renal transplantation. Use of induction therapy with a lymphocyte-depleting agent or an interleukin-2 receptor (IL-2R) antagonist can provide effective protection against rejection in the first critical weeks and months post-transplant. Polyclonal lymphocyte-depleting antibodies are associated with a low incidence of rejection but evidence of their benefit in terms of graft survival is lacking. Thymoglobulin appears to offer superior graft outcomes compared with generic antithymocyte globulin (ATG). The most frequent adverse events are symptoms of cytokine release syndrome, leukopenia, thrombocytopenia, and tachycardia; data on whether polyclonal antibody use increases the risk of lymphoma are conflicting. Muromonab CD3 (OKT3), a monoclonal lymphocyte-depleting antibody, is efficacious but a high incidence of cytokine release syndrome and increased risk of post-transplant lymphoproliferative disease have limited its use. Following their recent introduction, the IL-2R antagonists basiliximab and daclizumab are now used widely, after randomized trials demonstrated that addition to calcineurin inhibitor-based therapy significantly reduced acute rejection by approximately 30-40%. Meta-analyses and registry analysis suggest that addition of an IL-2R antagonist may improve graft survival. The safety profile of IL-2R antagonists is indistinguishable from placebo, with no apparent difference in incidence of infection or post-transplant lymphoproliferative disease. IL-2R antagonists and polyclonal lymphocyte-depleting antibodies (with delayed cyclosporine) offer equivalent efficacy in standard-risk populations; in a trial of high-risk patients, acute rejection rate and graft outcomes were improved with Thymoglobulin. Tolerability is superior with IL-2R antagonists: cytokine release syndrome and hematologic disturbances (notably leukopenia) are significantly more frequent with polyclonal antibodies. Cytomegalovirus infection may also be more common with lymphocyte-depleting antibodies. Thus, in patients at high risk of graft loss, Thymoglobulin may be the preferred choice for induction therapy, while for all other patients, IL-2R antagonists should be considered first-line choice for induction therapy.

Daclizumab induction in solid organ transplantation

Antibody induction therapy is used in solid organ transplantation to prevent rejection in the early postoperative period. It is especially useful in high-risk groups such as retransplants, patients with delayed graft function to delay the initiation of nephrotoxic calcineurin inhibitors (tacrolimus, cyclosporin), highly sensitised recipients and African-American recipients. Historically, antibody induction has been associated with a high incidence of adverse effects and a complicated administration regimen. Daclizumab is a monoclonal antibody that exerts its effect by binding to the alpha subunit (CD25) of the human interleukin (IL)-2 receptor on the surface of activated lymphocytes, thus preventing the binding of IL-2. It is used for induction therapy and is well-tolerated with easy administration. Although originally studied as a five-dose regimen, there is a growing accumulation of data that fewer doses (two or three) are efficacious and less costly for preventing rejection.

Daclizumab is Associated With Decreased Rejection and No Increased Mortality in Cardiac Transplant Patients Receiving MMF, Cyclosporine, and Corticosteroids

BACKGROUND

Sparse published data exist on outcomes in daclizumab-treated cardiac transplant patients. One trial observed an increased mortality risk 6 and 12 months posttransplant in patients receiving daclizumab plus mycophenolate mofetil (MMF), cyclosporine, and steroids. This study further investigates the safety profile of daclizumab with this same immunosuppressive regimen from a large registry.

METHODS

Data obtained at hospital discharge on all adult cardiac transplants performed in the USA between January 1998 and October 2003 for patients receiving MMF plus cyclosporine and steroids were accessed from the Scientific Registry of Transplant Recipients. Patients were selected based on induction treatment: daclizumab (n = 684) or no induction (n = 2525). Outcomes were evaluated at 6 months, 12 months, and 3 years posttransplant. Univariate Kaplan-Meier and multivariate Cox models were used to evaluate the effect of treatment on outcomes. Patient survival and infectious death were the primary endpoints. Secondary endpoints included rejection within the first year posttransplant (acute rejection; AR) and total rejection episodes over time. The two treatment groups shared similar demographics and transplant procedure details.

RESULTS

Daclizumab (vs no induction) patients had no increased risk of patient death nor infectious death. Daclizumab patients had a lower incidence of AR at 6 months (P = .005) and 12 months (P < .001); the adjusted risk for AR at 12 months (hazards ratio [HR] = 0.77; P = .89) and over 3 years (HR 0.83, P = .006) was also lower in daclizumab-treated patients.

CONCLUSIONS

In cardiac transplant patients, daclizumab (vs no induction) does not result in increased mortality or infectious death, and is associated with a lower incidence of AR.

Early experience with two-dose daclizumab in the prevention of acute rejection in cardiac transplantation

BACKGROUND

Daclizumab is a human monoclonal antibody that binds to the interleukin-2 receptor. It has been used as induction therapy in heart transplantation with repeated administrations over several weeks. At our institution, we use a two-dose regimen of daclizumab based on its extended half-life. We sought to determine the incidence of acute rejection with 2-dose daclizumab in cardiac transplantation.

METHODS

Eighteen consecutive heart transplants performed at a single center were analyzed retrospectively. Patients received daclizumab (2 mg/kg) within 8 h of cardiac transplantation and a second dose (1 mg/kg) 2 wk thereafter. Maintenance immunosupression included mycophenolate mofetil, prednisone and either cyclosporine or tacrolimus, based on side-effect profile. The endpoint was the incidence of acute rejection as defined by a histologic grade >2 according to the classification of the International Society of Heart and Lung Transplantation.

RESULTS

Four patients had acute rejections (all were 3A) during the first 3 months post-transplantation. All four patients had rejection at the first biopsy and only two had rejection thereafter. None of the rejections were hemodynamically significant and no patients were hospitalized. All except one rejection was seen in the context of low 2-h cyclosporine levels. The two-dose regimen was easier to administer on an outpatient basis and resulted in lower cost.

CONCLUSIONS

This preliminary report suggests that induction therapy with a two-dose regimen of daclizumab appears to be safe and well tolerated in patients undergoing cardiac transplantation.

Anti-Interleukin-2 Receptor Antibodies in Transplantation

Two monoclonal antibody preparations against the alpha-chain of the interleukin-2 receptor (IL-2Ralpha) are available for use, basiliximab and daclizumab, a chimeric and a humanised antibody, respectively. The first clinical studies have demonstrated the efficacy of these agents as induction therapy to reduce the rate of acute rejection after organ transplantation. Basiliximab and daclizumab have a similar effect on prevention of acute rejection. Likewise, incidence of infections and malignancies are not different between the two treatment options. Anti-IL-2Ralpha therapy was very well tolerated in clinical trials. Phase III studies with basiliximab have been undertaken with a two-dose regimen, consisting of two doses of 20mg, in an attempt to saturate the IL-2Ralpha on peripheral blood T lymphocytes for an average of 4-6 weeks. In contrast, the daclizumab dose is corrected for bodyweight and the goal is to achieve IL-2Ralpha blockade for 12 weeks. Phase III efficacy trials with daclizumab have, therefore, been developed with five doses of 1 mg/kg every 2 weeks in the first 2 months after transplantation. Whether or not it is a benefit to have blockade of the IL-2Ralpha for 10-12 weeks (daclizumab) compared with 4-6 weeks (basiliximab) remains unknown. Assuming 4-6 weeks would be sufficient for prevention of acute rejection, many centres have changed the protocol of daclizumab administration to two doses, the first dose given at the time of transplantation, the second 10 or 14 days after, with good success. Therefore, it seems feasible to limit the dose of daclizumab, which increases the ease of administration and probably also the cost effectiveness of this agent. There are no controlled studies comparing basiliximab and daclizumab, nor have different dose regimens been directly compared in renal transplantation. The data available suggest the differences are small, if present at all, and it is unlikely that such a trial will ever be done. With both compounds, a significant reduction in the number of acute rejection episodes following solid organ transplantation can be obtained without an increase in adverse effects or infectious complications.

The fractional excretion of soluble interleukin-2 receptor-?? is an excellent predictor of the interleukin-2 receptor-?? status after treatment with daclizumab

BACKGROUND

Daclizumab is a humanized monoclonal antibody against the alpha-chain of the interleukin (IL)-2 receptor (R). The authors previously have shown that the urinary excretion of soluble (s) IL-2Ralpha is dependent on the presence of daclizumab in serum. The authors investigated whether the IL-2Ralpha status, as assessed by flow cytometric analysis, is reflected by the concentration of sIL-2Ralpha in the urine and serum.

METHODS

Two hundred seventy-two measurements were performed in 46 renal transplant recipients who were treated with daclizumab in combination with tacrolimus and mycophenolate mofetil. Soluble IL-2Ralpha was measured in urine and serum with Immulite IL-2R, a solid-phase enzyme-linked immunosorbent assay. Complete blockade of the IL-2Ralpha was defined as the presence of less than 5% IL-2Ralpha+ lymphocytes in the CD3+ population. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the performance of serum and urine sIL-2Ralpha in predicting IL-2Ralpha blockade.

RESULTS

The calculated fractional excretion of sIL-2Ralpha proved to be an excellent predictor of the blockade of IL-2Ralpha (ROC analysis area under the curve, 0.95+/-0.01). A calculated fractional excretion of sIL-2Ralpha lower than 0.5% had a specificity of 100% and a sensitivity of 75% for the assessment of blockade of IL-2Ralpha.

CONCLUSIONS

Blockade of IL-2Ralpha after treatment with daclizumab can reliably be assessed by calculation of the fractional excretion of sIL-2Ralpha. This method is easier to use compared with flow cytometric analysis of IL-2Ralpha+ lymphocytes.

Single-dose daclizumab induction therapy in patients with liver transplantation

AIM: To investigate the efficacy and safety of a single-dose daclizumab induction therapy in orthotopic liver transplantation (OLTx).

METHODS: A retrospective study was made for 54 cases of OLTx in recent three years. The daclizumab group consisted of 23 cases of OLTx who received single-dose of 2 mg/kg intravenously after postoperative 24 hours. The control group consisted of the remaining 31 patients. Additional immunosuppressors included steroids, mycomphenolate mofetil, facrolimus or microemulsion cyclosporine used in all patients. Meta-statistical analysis was made for general data, incidence of acute rejection and infection, postoperative clinical course, complications and prognosis between two groups.

RESULTS: Pretransplant demographies were not significantly different between two groups. In the induction group there were significantly less acute rejection episodes (5 of 23, 21.74%) than those in the control group (12 of 31, 38.71%), which were proved by pathologic diagnosis (P < 0.05). The incidence of infection at the early stage was not significantly different between two groups.

CONCLUSION: Induction therapy with single-dose of daclizumab is safe and effective and appears to be able to reduce the incidence of acute rejection.

Pediatric liver transplantation with daclizumab induction

BACKGROUND

A new class of monoclonal antibodies (non-T-cell depleting) has gained favor for induction therapy after transplantation. This study evaluated the non-T-cell depleting antibody to the CD25 cell, daclizumab, as a single-dose induction agent immediately after pediatric liver transplantation to spare the use of the calcineurin inhibitor, tacrolimus, for 7 days in respect to both efficacy and renal function.

METHODS

From January 1998 to November 2001, 81 pediatric orthotopic liver transplant recipients receiving 89 liver grafts were evaluated. The treatment arm (n=61) received daclizumab 1 mg/kg immediately after liver transplantation along with mycophenolate, steroids, and, on postoperative day 7, tacrolimus. The control group did not receive induction therapy, whereas tacrolimus, mycophenolate, and steroids were started immediately after surgery.

RESULTS

The induction group had fewer patients with rejection within the first 30 days after liver transplantation (9 [14.8%] vs. 10 [50%]; P=0.003). The mean time to first rejection was similar between groups (12.1 [+/-7.8] days vs. 18.5 [+/-8.1] days; P=not significant). There was a 3.39 increase in relative risk to develop rejection within the first 30 days after orthotopic liver transplantation if the patient did not receive induction therapy (relative risk=3.39; 95% confidence interval [1.61, 7.14]). Two-year actuarial survival for the induction group was 93.2% compared with 85% in the control; graft survival was also similar between groups (87.8% vs. 72.7%) at 2 years.

CONCLUSION

Daclizumab 1 mg/kg given immediately after pediatric liver transplantation and withholding tacrolimus, is safe, efficacious, and reduces rejections within the first 30 days after surgery.

Long-term safety, tolerability and efficacy of daclizumab (Zenapax) in a two-dose regimen in liver transplant recipients

A major thrust of transplantation research is to find more effective and less broadly toxic immunosuppressive agents. One potential way is the use of monoclonal antibodies directed to IL-2R alpha. Immunoprophylaxis with daclizumab, a humanized anti-IL-2R alpha monoclonal antibody, has been shown to be effective in the prevention of acute rejection in kidney transplant patients. These results encouraged us to initiate a pilot study in 28 liver transplant patients in 1997. Daclizumab was administered intravenously approximately 6 h after reperfusion (1 mg/kg) and on day 4 post-transplant (0.5 mg/kg). Additional immunosuppression consisted of cyclosporine A as well as of corticosteroids. Administration of daclizumab was not associated with any side-effects. We only experienced one acute rejection in a patient on day 17 post-transplant. It resolved immediately under therapy with prednisolone. The rate of opportunistic infections did not differ from results with conventional immunosuppressive regimens. At 4 years post-transplant no lymphoproliferative disease was observed. Patient survival at 12, 24, 36 and 48 months post-transplant was 88.5, 84.6, 80.8 and 73.1%, respectively. Immunoprophylaxis with a two-dose daclizumab regimen is safe, effective and well tolerated, and does not lead to increased opportunistic infections.