CAMPATH-1H, a humanized monoclonal antibody, in refractory rheumatoid arthritis. An intravenous dose-escalation study

Alemtuzumab-induced autoimmune thyroid events in patients with relapsing-remitting multiple sclerosis: A real-life and monocentric experience at a tertiary-level centre

OBJECTIVE

Alemtuzumab-induced autoimmune thyroid events (AIATEs) are the most common adverse effects observed in relapsing-remitting multiple sclerosis (RRMS) patients. This study aims to explore the clinical and biochemical characteristics of such AIATEs, and to examine the risk factors for their occurrence, particularly for the worst clinical phenotype of fluctuating Graves' disease (GD).

DESIGN, PATIENTS, MEASUREMENTS

We retrospectively analysed a real-life single-centre consecutive series of 57 RRMS patients treated with alemtuzumab whose clinical and biochemical parameters were collected before starting the treatment and then monthly during their follow-up.

RESULTS

AIATEs developed in 39% of patients a mean 17 months ± 11 after the first cycle of alemtuzumab. The most common AIATEs were GD (64%), followed by Hashimoto's thyroiditis with hypothyroidism (23%), TSH-receptor-antibody (TRAb)-positive hypothyroidism (9%), and silent thyroiditis (4%). GD showed a fluctuating course in 57% of cases. Baseline positivity for anti-thyroperoxidase antibodies, and higher absolute titers of anti-thyroglobulin and anti-thyroperoxidase antibodies correlated significantly with the risk of developing AIATEs, but TRAb positivity did not. Higher TRAb titers at the time of GD being diagnosed correlated strongly with a greater risk of the fluctuating GD phenotype. On ROC curve analysis, we found that a cut-off of 7.3 IU/L could be used to predict the risk of developing a fluctuating GD, with a positive predictive value of 100%.

CONCLUSIONS

TRAb levels measured with commercial automatic methods at the time of a patient being diagnosed with alemtuzumab-induced GD emerged as a novel biomarker for predicting a fluctuating disease phenotype, with an influence on subsequent therapeutic decisions and patients' follow-up.

Treatment approaches to patients with multiple sclerosis and coexisting autoimmune disorders

The past decades have yielded major therapeutic advances in many autoimmune conditions - such as multiple sclerosis (MS) - and thus ushered in a new era of more targeted and increasingly potent immunotherapies. Yet this growing arsenal of therapeutic immune interventions has also rendered therapy much more challenging for the attending physician, especially when treating patients with more than one autoimmune condition. Importantly, some therapeutic strategies are either approved for several autoimmune disorders or may be repurposed for other conditions, therefore opening new curative possibilities in related fields. In this article, we especially focus on frequent and therapeutically relevant concomitant autoimmune conditions faced by neurologists when treating patients with MS, namely psoriasis, rheumatoid arthritis and inflammatory bowel diseases. We provide an overview of the available disease-modifying therapies, highlight possible contraindications, show pathophysiological overlaps and finally present which therapeutics can be utilized as a combinatory treatment, in order to 'kill two birds with one stone'.

Development of a structure-based computational simulation to optimize the blocking efficacy of pro-antibodies

The on-target toxicity of monoclonal antibodies (Abs) is mainly due to the fact that Abs cannot distinguish target antigens (Ags) expressed in disease regions from those in normal tissues during systemic administration. In order to overcome this issue, we “copied” an autologous Ab hinge as an “Ab lock” and “pasted” it on the binding site of the Ab by connecting a protease substrate and linker in between to generate a pro-Ab, which can be specifically activated in the disease region to enhance Ab selectivity and reduce side effects. Previously, we reported that 70% of pro-Abs can achieve more than 100-fold blocking ability compared to the parental Abs. However, 30% of pro-Abs do not have such efficient blocking ability. This is because the same Ab lock linker cannot be applied to every Ab due to the differences in the complementarity-determining region (CDR) loops. Here we designed a method which uses structure-based computational simulation (MSCS) to optimize the blocking ability of the Ab lock for all Ab drugs. MSCS can precisely adjust the amino acid composition of the linker between the Ab lock and Ab drug with the assistance of molecular simulation. We selected αPD-1, αIL-1β, αCTLA-4 and αTNFα Ab as models and attached the Ab lock with various linkers (L1 to L7) to form pro-Abs by MSCS, respectively. The resulting cover rates of the Ab lock with various linkers compared to the Ab drug were in the range 28.33–42.33%. The recombinant pro-Abs were generated by MSCS prediction in order to verify the application of molecular simulation for pro-Ab development. The binding kinetics effective concentrations (EC-50) for αPD-1 (200-250-fold), αIL-1β (152-186-fold), αCTLA-4 (68-150-fold) and αTNFα Ab (20-123-fold) were presented as the blocking ability of pro-Ab compared to the Ab drug. Further, there was a positive correlation between cover rate and blocking ability of all pro-Ab candidates. The results suggested that MSCS was able to predict the Ab lock linker most suitable for application to αPD-1, αIL-1β, αCTLA-4 and αTNFα Ab to form pro-Abs efficiently. The success of MSCS in optimizing the pro-Ab can aid the development of next-generation pro-Ab drugs to significantly improve Ab-based therapies and thus patients' quality of life.

The pro-Ab blocks the Ag binding site using an Ab lock. We designed a method which uses structure-based computational simulation (MSCS) to predict the cover rate of Ab locks with various linkers and select the suitable linker for each Ab.

The Irony of Humanization: Alemtuzumab, the First, But One of the Most Immunogenic, Humanized Monoclonal Antibodies

Alemtuzumab was designed to reduce the immunogenicity of the parent CD52-specific rat immunoglobulin. Although originally marketed for use in cancer (Mabcampath®), alemtuzumab is currently licensed and formulated for the treatment of relapsing multiple sclerosis (Lemtrada®). Perhaps due to its history as the first humanized antibody, the potential of immunogenicity of the molecule has been considered inconsequential, and anti-drug antibodies (ADA) responses were similarly reported as being clinically insignificant. Nonetheless, despite humanization and depletion of peripheral T and B cells, alemtuzumab probably generates the highest frequency of binding and neutralizing ADA of all humanized antibodies currently in clinical use, and they occur rapidly in a large majority of people with MS (pwMS) on alemtuzumab treatment. These ADA appear to be an inherent issue of the biology of the molecule-and more importantly, the target-such that avoidance of immunogenicity-related effects has been facilitated by the dosing schedule used in clinical practice. At the population level this enables the drug to work in most pwMS, but in some individuals, as we show here, antibody neutralization appears to be sufficiently severe to reduce efficacy and allow disease breakthrough. It is therefore imperative that efficacy of lymphocyte depletion and the anti-drug response is monitored in people requiring additional cycles of treatment, notably following disease breakthrough. This may help inform whether to re-treat or to switch to another disease-modifying treatment.

Specific activation of pro-Infliximab enhances selectivity and safety of rheumatoid arthritis therapy

During rheumatoid arthritis (RA) treatment, long-term injection of antitumor necrosis factor α antibodies (anti-TNFα Abs) may induce on-target toxicities, including severe infections (tuberculosis [TB] or septic arthritis) and malignancy. Here, we used an immunoglobulin G1 (IgG1) hinge as an Ab lock to cover the TNFα-binding site of Infliximab by linking it with matrix metalloproteinase (MMP) -2/9 substrate to generate pro-Infliximab that can be specifically activated in the RA region to enhance the selectivity and safety of treatment. The Ab lock significantly inhibits the TNFα binding and reduces the anti-idiotypic (anti-Id) Ab binding to pro-Infliximab by 395-fold, 108-fold compared with Infliximab, respectively, and MMP-2/9 can completely restore the TNFα neutralizing ability of pro-Infliximab to block TNFα downstream signaling. Pro-Infliximab was only selectively activated in the disease site (mouse paws) and presented similar pharmacokinetics (PKs) and bio-distribution to Infliximab. Furthermore, pro-Infliximab not only provided equivalent therapeutic efficacy to Infliximab but also maintained mouse immunity against Listeria infection in the RA mouse model, leading to a significantly higher survival rate (71%) than that of the Infliximab treatment group (0%). The high-selectivity pro-Infliximab maintains host immunity and keeps the original therapeutic efficiency, providing a novel strategy for RA therapy.

During treatment of rheumatoid arthritis, systemic administration of anti-TNFα antibodies may induce on-target toxicities, limiting their application. The incorporation of IgG1 hinge as an antibody lock generates a pro-Infliximab whose activation is specific to the disease region, enabling safer RA therapy.

Phage display antibody libraries: A robust approach for generation of recombinant human monoclonal antibodies

Monoclonal antibodies (mAbs) and their derivatives have achieved remarkable success as medicine, targeting both diagnostic and therapeutic applications associated with communicable and non-communicable diseases. In the last 3 to 4 decades, tremendous success has been manifested in the field of cancer therapy, autoimmune diseases, cardiovascular and infectious diseases. MAbs are the fastest growing class of biopharmaceuticals, with more than 25 derivatives are in clinical use and 7 of these have been isolated through phage display technology. Phage display technology has gained impetus in the field of medical and health sciences, as a large repertoire of diverse recombinant antibodies, targeting various antigens have been generated in a short span of time. A prominent number of phage display derived antibodies are already approved for therapy and significant numbers are currently in clinical trials. In this review we have discussed the various strategies employed for generation of monoclonal antibodies; their advantages, limitations and potential therapeutic applications. We also discuss the potential of phage display antibody libraries in isolation of monoclonal antibodies.

Clinical pharmacology of alemtuzumab, an anti-CD52 immunomodulator, in multiple sclerosis

Alemtuzumab, a humanized anti‐CD52 monoclonal antibody, is approved for treatment of relapsing multiple sclerosis (MS). In the Phase II/III trials, patients received 12 or 24 mg/day of alemtuzumab in two treatment courses (5 days for course 1 and 3 days for course 2), 12 months apart. Serum concentrations of alemtuzumab peaked on the last day of dosing in each course and mostly fell below the limit of quantitation by day 30. Alemtuzumab rapidly depleted circulating T and B lymphocytes, with the lowest observed values occurring within days. Lymphocytes repopulated over time, with B cell recovery usually complete within 6 months. T lymphocytes recovered more slowly and generally did not return to baseline by 12 months post‐treatment. Approximately 40 and 80% of patients had total lymphocyte counts, reaching the lower limit of normal by 6 and 12 months after each course, respectively. The clearance of alemtuzumab is dependent on circulating lymphocyte count. A majority of treated patients tested positive for anti‐alemtuzumab antibodies, including inhibitory antibodies, during the 2‐year studies, and a higher proportion of patients tested positive in course 2 than in course 1. The presence of anti‐alemtuzumab antibody appeared to be associated with slower clearance of alemtuzumab from the circulation but had no impact on the pharmacodynamics. No effects of age, race or gender on the pharmacokinetics or pharmacodynamics were observed. Together, the pharmacokinetics, pharmacodynamics and immunogenicity results support the continued development and use of alemtuzumab for the treatment of MS, and probably explain its sustained effects beyond the dosing interval.

Life-threatening autoimmune warm hemolytic anemia following treatment for multiple sclerosis with alemtuzumab

Background:

Alemtuzumab is a humanized monoclonal antibody directed at CD52 approved as a disease-modifying therapy for relapsing forms of multiple sclerosis (MS).

Objective:

To describe a case of a life-threatening autoimmune anemia occurring after a first course of alemtuzumab for relapsing-remitting MS in a 28-year-old male.

Methods:

Case report.

Results:

A 28-year-old male developed a life-threatening autoimmune anemia occurring 11 months after first alemtuzumab course.

Conclusion:

We report the third case of autoimmune hemolytic anemia following treatment with alemtuzumab in a young MS patient. Due to the severity of this adverse event, neurologists using this treatment should be alert.

Alemtuzumab depletion failure can occur in multiple sclerosis

Alemtuzumab is a lymphocyte-depleting antibody and one of the most effective treatments for relapsing multiple sclerosis. However, it also causes loss of immune-tolerance leading to secondary autoimmunity and marked anti-drug antibody responses. Although these anti-drug responses have been reported to be of no significance, we hypothesized that they will affect the depleting capacity and treatment response in some individuals. This was found following analysis of the regulatory submission of the pivotal phase III trials, which was obtained from the European Medicines Agency. At the population level there was lack of influence of 'ever-positive' alemtuzumab-specific antibody responses on lymphocyte depletion, clinical efficacy and adverse effects during the 2-year trial. This was not surprising as no one before the first infusion, and only 0·6% of people before the second-infusion, had pre-infusion, neutralizing antibodies (NAbs). However, at the individual level, NAbs led to poor lymphocyte depletion. Importantly, it was evident that 31% of people had NAbs and 75% had binding antibodies at the end of treatment-cycle 2, which suggests that problems may occur in people requiring additional alemtuzumab cycles. In addition, we also identified individuals, following 'post-marketing' alemtuzumab use, whose lymphocyte level was never effectively depleted after the first infusion cycle. Hence, although alemtuzumab depletes lymphocytes in most individuals, some people fail to deplete/deplete poorly, probably due to biological-response variation and NAbs, and this may lead to treatment failure. Monitoring depletion following infusion and assessment of the neutralizing response before re-infusion may help inform the decision to retreat or switch therapy to limit treatment failure.

Alemtuzumab

Each month, subscribers to The Formulary® Monograph Service receive five to six well-documented monographs on drugs that are newly released or are in late Phase III trials. The monographs are targeted to your Pharmacy and Therapeutics Committee. Subscribers also receive monthly one-page summary monographs on the agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation (DUE) is also provided each month. The monographs are published in printed form and on diskettes that allow customization. Subscribers to the The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X.

Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. If you would like information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The September 2001 Formulary monograph topics are telithromycin, trivalent influenza vaccine, drotrecogin alfa, pime-crolimus cream, zoledronic acid, and brimonidine tartrate opththalmic solution. The DUE is on almotriptan maleate.

Characterization of CD4 T Cell Epitopes of Infliximab and Rituximab Identified from Healthy Donors

The chimeric antibodies anti-CD20 rituximab (Rtx) and anti-TNFα infliximab (Ifx) induce antidrug antibodies (ADAs) in many patients with inflammatory diseases. Because of the key role of CD4 T lymphocytes in the initiation of antibody responses, we localized the CD4 T cell epitopes of Rtx and Ifx. With the perspective to anticipate immunogenicity of therapeutic antibodies, identification of the CD4 T cell epitopes was performed using cells collected in healthy donors. Nine T cell epitopes were identified in the variable chains of both antibodies by deriving CD4 T cell lines raised against either Rtx or Ifx. The T cell epitopes often exhibited a good affinity for human leukocyte antigen (HLA)-DR molecules and were part of the peptides identified by MHC-associated peptide proteomics assay from HLA-DR molecules of dendritic cells (DCs) loaded with the antibodies. Two-third of the T cell epitopes identified from the healthy donors stimulated peripheral blood mononuclear cells from patients having developed ADAs against Rtx or Ifx and promoted the secretion of a diversity of cytokines. These data emphasize the predictive value of evaluating the T cell repertoire of healthy donors and the composition of peptides bound to HLA-DR of DCs to anticipate and prevent immunogenicity of therapeutic antibodies.

Phage display-derived human antibodies in clinical development and therapy

Over the last 3 decades, monoclonal antibodies have become the most important class of therapeutic biologicals on the market. Development of therapeutic antibodies was accelerated by recombinant DNA technologies, which allowed the humanization of murine monoclonal antibodies to make them more similar to those of the human body and suitable for a broad range of chronic diseases like cancer and autoimmune diseases. In the early 1990s in vitro antibody selection technologies were developed that enabled the discovery of “fully” human antibodies with potentially superior clinical efficacy and lowest immunogenicity.

Antibody phage display is the first and most widely used of the in vitro selection technologies. It has proven to be a robust, versatile platform technology for the discovery of human antibodies and a powerful engineering tool to improve antibody properties. As of the beginning of 2016, 6 human antibodies discovered or further developed by phage display were approved for therapy. In 2002, adalimumab (Humira®) became the first phage display-derived antibody granted a marketing approval. Humira® was also the first approved human antibody, and it is currently the best-selling antibody drug on the market. Numerous phage display-derived antibodies are currently under advanced clinical investigation, and, despite the availability of other technologies such as human antibody-producing transgenic mice, phage display has not lost its importance for the discovery and engineering of therapeutic antibodies.

Here, we provide a comprehensive overview about phage display-derived antibodies that are approved for therapy or in clinical development. A selection of these antibodies is described in more detail to demonstrate different aspects of the phage display technology and its development over the last 25 years.

Novel Immunotherapeutic Avenues for Rheumatoid Arthritis

Rheumatoid arthritis (RA) is the most common inflammatory rheumatic disease. It leads to irreversible joint damage, physical handicap, and reduced life expectancy. The past two decades have seen considerable therapeutic advances with the development of biologic treatments to block proinflammatory cytokines or modulate lymphocyte function, followed by the development of small molecules to target intracellular signaling. Nevertheless, only a minority of patients can achieve disease remission, especially long term, warranting further investigation into newer therapeutic options. Targeting single proinflammatory pathways may not be sufficient, as suggested by variable results with T helper (Th)-17-related cytokine blockade. Multilevel information from 'omics' techniques along with data from mechanistic studies might facilitate the identification of pivotal checkpoints in RA disease pathogenesis and the subsequent development of new effective treatments.

Characterisation of a Novel Anti-CD52 Antibody with Improved Efficacy and Reduced Immunogenicity

Anti-CD52 therapy has been shown to be effective in the treatment of a number of B cell malignancies, hematopoietic disorders and autoimmune diseases (including rheumatoid arthritis and multiple sclerosis); however the current standard of treatment, the humanized monoclonal antibody alemtuzumab, is associated with the development of anti-drug antibodies in a high proportion of patients. In order to address this problem, we have identified a novel murine anti-CD52 antibody which has been humanized using a process that avoids the inclusion within the variable domains of non-human germline MHC class II binding peptides and known CD4+ T cell epitopes, thus reducing its potential for immunogenicity in the clinic. The resultant humanized antibody, ANT1034, was shown to have superior binding to CD52 expressing cells than alemtuzumab and was more effective at directing both antibody dependent and complement dependent cell cytotoxicity. Furthermore, when in the presence of a cross-linking antibody, ANT1034 was more effective at directly inducing apoptosis than alemtuzumab. ANT1034 also showed superior activity in a SCID mouse/human CD52 tumour xenograft model where a single 1 mg/Kg dose of ANT1034 led to increased mouse survival compared to a 10 mg/Kg dose of alemtuzumab. Finally, ANT1034 was compared to alemtuzumab in in vitro T cell assays in order to evaluate its potential to stimulate proliferation of T cells in peripheral blood mononuclear cells derived from a panel of human donors: whereas alemtuzumab stimulated proliferation in a high proportion of the donor cohort, ANT1034 did not stimulate proliferation in any of the donors. Therefore we have developed a candidate therapeutic humanized antibody, ANT1034, that may have the potential to be more efficacious and less immunogenic than the current standard anti-CD52 therapy.

Emerging therapies for rheumatoid arthritis

INTRODUCTION

With the introduction of biologic therapies, tremendous progress has been made in the treatment of rheumatoid arthritis (RA). However, up to 40% of patients do not respond to these treatments.

AREAS COVERED

Several new treatment strategies are discussed, with brief overview of currently performed clinical trials. The development of molecules targeting cytokines other than TNF is discussed, as well as chemokine-directed drugs. Finally, the area of small molecular inhibitors is explored.

EXPERT OPINION

Since RA is a life-long disease often evolving into disability, development of new treatment strategies remains crucial. Especially small molecules targeting JAK, Syk and PDE4 may provide novel therapeutic options.

A review of Campath in autoimmune disease: Biologic therapy in the gray zone between immunosuppression and immunoablation

Campath, the subject of this review, is an example of a broadly targeted biologic agent, approved for patients with B-CLL, which may combine immunosuppressive as well as immunoablative properties. For many years Campath has been in clinical use as an immunosuppressive agent for various autoimmune diseases and as part of the preparative regimes for allogeneic HSCT, successfully preventing graft-versus-host-disease (GVHD). This review summarizes the experience of 24 studies including a total of 323 patients treated with Campath for various autoimmune diseases such as arthritis, MS, vasculitis, autoimmune cytopenias and others. The results demonstrate that Campath is fairly safe and 75% of the patients experienced clinical improvement and 15% of the patients were reported in clinical remission even though improvements were often transient.While other biologic drugs may have to narrow targets, Campath, is able to bridge the gap between immunosuppression and immunoablation and may offer an alternative to human stem cell transplantation avoiding the risks of chemotherapy and radiation.

Pharmacotherapy: concepts of pathogenesis and emerging treatments. Co-stimulation and T cells as therapeutic targets

Full activation and differentiation of resting T cells into effector T cells requires at least two signals, the first through engagement of the T cell antigen receptor (TCR) by the antigen-major histocompatibility complex (MHC) on antigen-presenting cells (APCs), and the second by engagement of co-stimulatory molecules such as CD28, on T cells by ligands such as CD80/86 on APCs. Effector T cell differentiation is associated with proliferation, secretion of cytokines and expression of additional surface molecules. These inducible structures may have stimulatory (ICOS, OX40 and 4-1BB) or inhibitory (cytotoxic T-lymphocyte antigen (CTLA)-4) potential. To the extent that T cells have a role in particular immune-mediated diseases, interruption of T cell co-stimulation is a potentially worthwhile approach to the treatment of those conditions. This article summarises the experience in treating rheumatological disease by perturbation of T cell co-stimulation, and also describes structures that could be future targets for this type of therapeutic approach.

Oxidized ATP inhibits T-cell-mediated autoimmunity

T cells directed against self antigens play an important role in several autoimmune diseases. The available immunosuppressive compounds used to treat autoimmune diseases are limited, and often they have side effects that limit their application. T cells express ATP receptors, which could be new target molecules to treat autoimmune disease. Here we analyzed the effect of oxidized ATP (oxATP), an inhibitor of the ATP receptor P2rx7, in different murine models of T-cell-mediated autoimmune diseases. Treatment with oxATP inhibited proliferation and effector function of T cells. In the systems we used, oxATP did not obviously interfere with the innate immune response, but strongly reduced antigen-specific T-cell responses. This treatment ameliorated T-cell-mediated autoimmune type I diabetes and autoimmune encephalitis in mice. In conclusion, oxATP was found to strongly inhibit activated T cells and could thus be used to target T-cell-mediated autoimmune disease.

Have we overestimated the benefit of human(ized) antibodies?

The infusion of animal-derived antibodies has been known for some time to trigger the generation of antibodies directed at the foreign protein as well as adverse events including cytokine release syndrome. These immunological phenomena drove the development of humanized and fully human monoclonal antibodies. The ability to generate human(ized) antibodies has been both a blessing and a curse. While incremental gains in the clinical efficacy and safety for some agents have been realized, a positive effect has not been observed for all human(ized) antibodies. Many human(ized) antibodies trigger the development of anti-drug antibody responses and infusion reactions. The current belief that antibodies need to be human(ized) to have enhanced therapeutic utility may slow the development of novel animal-derived monoclonal antibody therapeutics for use in clinical indications. In the case of murine antibodies, greater than 20% induce tolerable/negligible immunogenicity, suggesting that in these cases humanization may not offer significant gains in therapeutic utility. Furthermore, humanization of some murine antibodies may reduce their clinical effectiveness. The available data suggest that the utility of human(ized) antibodies needs to be evaluated on a case-by-case basis, taking a cost-benefit approach, taking both biochemical characteristics and the targeted therapeutic indication into account.

A novel strategy to reduce the immunogenicity of biological therapies

Biological therapies, even humanized mAbs, may induce antiglobulin responses that impair efficacy. We tested a novel strategy to induce tolerance to a therapeutic mAb. Twenty patients with relapsing-remitting multiple sclerosis received an initial cycle of alemtuzumab (Campath-1H), up to 120 mg over 5 d, preceded by 500 mg SM3. This Ab differs from alemtuzumab by a single point mutation and is designed not to bind to cells. Twelve months later, they received a second cycle of alemtuzumab, up to 72 mg over 3 d. One month after that, 4 of 19 (21%) patients had detectable serum anti-alemtuzumab Abs compared with 145 of 197 (74%) patients who received two cycles of alemtuzumab without SM3 in the phase 2 CAMMS223 trial (p < 0.001). The efficacy and safety profile of alemtuzumab was unaffected by SM3 pretreatment. Long-lasting "high-zone" tolerance to a biological therapy may be induced by pretreatment with a high i.v. dose of a drug variant, altered to reduce target-binding.

Clinically validated approaches to the treatment of autoimmune diseases

IMPORTANCE OF THE FIELD

Autoimmune diseases are pathological conditions in which "self-tolerance" has been broken, and an immune response has been mounted against the body's own tissues. More than seventy autoimmune diseases have been described, some of which are systemic and others of which are organ-specific. Although many of these diseases are rare, the collective prevalence of autoimmune diseases in the United States alone is between 5 and 8%, and is increasing.

AREAS COVERED IN THIS REVIEW

Herein, we review the exciting advances made during the past decade (1999 - 2009) in the development of clinically-validated agents for the treatment of autoimmune disease. We focus on five of the most prevalent conditions: rheumatoid arthritis, psoriasis, multiple sclerosis, Crohn's disease, and systemic lupus erythematosus. The discussion is largely restricted to agents - both small molecules and macromolecules - that have advanced through randomized, controlled clinical trials.

WHAT THE READER WILL GAIN

An overview of the pathogenesis of each disease is provided, along with a description of the therapies. Results from pivotal clinical trials are tabulated for four of the disease areas. We also provide summaries of experiences with both failed clinical trials and side effects observed during the course of clinical investigations. We conclude the review with thoughts on current challenges in the field and the prospect for future innovations.

TAKE HOME MESSAGE

During the past decade, some of the largest advances in the treatment of autoimmune disease have arisen from highly potent and selective macromolecule-based therapies (e.g. antibodies, recombinant proteins and fusion proteins). Together, these clinical experiences have provided insight into the critical mechanisms in autoimmune pathogenesis, including inflammatory cytokine release, T-cell migration and co-stimulation, and B-cell function.

Alemtuzumab in the treatment of IVIG-dependent chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an idiopathic immune mediated neuropathy causing demyelination and conduction block thought to occur as the result of an aberrant autoimmune response resulting in peripheral nerve inflammation mediated by T cells and humoral factors. Diagnosis commonly prompts initial treatment with steroids or intravenous immunoglobulin (IVIG) on which 5-35% subsequently become dependent to maintain function. Despite a number of small scale trials, the role for alternative long-term immunosuppression remains unclear. Alemtuzumab is a humanised monoclonal antibody targeting the CD52 antigen present on the surface of lymphocytes and monocytes. A single intravenous infusion results in rapid and profound lymphopoenia lasting >12 months. We report its use and clinical outcome in a small series of patients with severe IVIG-dependent CIDP. Seven patients (4 Males; 3 Females) who had failed to respond to conventional immunosuppression were treated in 5 centres receiving 9 courses of alemtuzumab (dose range 60-150 mg). Following treatment, mean monthly IVIG use fell 26% from 202 to 149 g and IVIG administration frequency from 22 to 136 days. Two patients had prolonged remission, two patients had a partial response and no clear benefit was observed in the remaining three patients (2 Males, 1 Females). Responding patients had a younger age at onset (19.5 years) and shorter disease duration than non-responders. Three patients developed autoimmune disease following treatment. Alemtuzumab may offer an alternative treatment for a subset of early onset IVIG dependent CIDP patients failing conventional immunosuppressive agents, but concerns about toxicity may limit its use.

T cell epitope: friend or foe? Immunogenicity of biologics in context

Like vaccines, biologic proteins can be very immunogenic for reasons including route of administration, dose frequency and the underlying antigenicity of the therapeutic protein. Because the impact of immunogenicity can be quite severe, regulatory agencies are developing risk-based guidelines for immunogenicity screening. T cell epitopes are at the root of the immunogenicity issue. Through their presentation to T cells, they activate the process of anti-drug antibody development. Preclinical screening for T cell epitopes can be performed in silico, followed by in vitro and in vivo validation. Importantly, screening for immunogenicity is complicated by the discovery of regulatory T cell epitopes, which suggests that immunogenicity testing must now take regulatory T cells into consideration. In this review, we address the application of computational tools for preclinical immunogenicity assessment, the implication of the discovery of regulatory T cell epitopes, and experimental validation of those assessments.

Effect of Alemtuzumab (CAMPATH 1-H) in patients with inclusion-body myositis

Sporadic inclusion-body myositis (sIBM) is the most common disabling, adult-onset, inflammatory myopathy histologically characterized by intense inflammation and vacuolar degeneration. In spite of T cell-mediated cytotoxicity and persistent, clonally expanded and antigen-driven endomysial T cells, the disease is resistant to immunotherapies. Alemtuzumab is a humanized monoclonal antibody that causes an immediate depletion or severe reduction of peripheral blood lymphocytes, lasting at least 6 months. We designed a proof-of-principle study to examine if one series of Alemtuzumab infusions in sIBM patients depletes not only peripheral blood lymphocytes but also endomysial T cells and alters the natural course of the disease. Thirteen sIBM patients with established 12-month natural history data received 0.3 mg/kg/day Alemtuzumab for 4 days. The study was powered to capture > or =10% increase strength 6 months after treatment. The primary end-point was disease stabilization compared to natural history, assessed by bi-monthly Quantitative Muscle Strength Testing and Medical Research Council strength measurements. Lymphocytes and T cell subsets were monitored concurrently in the blood and the repeated muscle biopsies. Alterations in the mRNA expression of inflammatory, stressor and degeneration-associated molecules were examined in the repeated biopsies. During a 12-month observation period, the patients' total strength had declined by a mean of 14.9% based on Quantitative Muscle Strength Testing. Six months after therapy, the overall decline was only 1.9% (P < 0.002), corresponding to a 13% differential gain. Among those patients, four improved by a mean of 10% and six reported improved performance of daily activities. The benefit was more evident by the Medical Research Council scales, which demonstrated a decline in the total scores by 13.8% during the observation period but an improvement by 11.4% (P < 0.001) after 6 months, reaching the level of strength recorded 12 months earlier. Depletion of peripheral blood lymphocytes, including the naive and memory CD8+ cells, was noted 2 weeks after treatment and persisted up to 6 months. The effector CD45RA(+)CD62L(-) cells, however, started to increase 2 months after therapy and peaked by the 4th month. Repeated muscle biopsies showed reduction of CD3 lymphocytes by a mean of 50% (P < 0.008), most prominent in the improved patients, and reduced mRNA expression of stressor molecules Fas, Mip-1a and alphaB-crystallin; the mRNA of desmin, a regeneration-associated molecule, increased. This proof-of-principle study provides insights into the pathogenesis of inclusion-body myositis and concludes that in sIBM one series of Alemtuzumab infusions can slow down disease progression up to 6 months, improve the strength of some patients, and reduce endomysial inflammation and stressor molecules. These encouraging results, the first in sIBM, warrant a future study with repeated infusions

Immunogenicity of biologically-derived therapeutics: assessment and interpretation of nonclinical safety studies

An evaluation of potential antibody formation to biologic therapeutics during the course of nonclinical safety studies and its impact on the toxicity profile is expected under current regulatory guidance and is accepted standard practice. However, approaches for incorporating this information in the interpretation of nonclinical safety studies are not clearly established. Described here are the immunological basis of anti-drug antibody formation to biopharmaceuticals (immunogenicity) in laboratory animals, and approaches for generating and interpreting immunogenicity data from nonclinical safety studies of biotechnology-derived therapeutics to support their progression to clinical evaluation. We subscribe that immunogenicity testing strategies should be adapted to the specific needs of each therapeutic development program, and data generated from such analyses should be integrated with available clinical and anatomic pathology, pharmacokinetic, and pharmacodynamic data to properly interpret nonclinical studies.

New approaches to prediction of immune responses to therapeutic proteins during preclinical development

Clinical studies show that immunogenicity observed against therapeutic proteins can limit efficacy and reduce the safety of the treatment. It is therefore beneficial to be able to predict the immunogenicity of therapeutic proteins before they enter the clinic. Studies using deimmunized proteins have highlighted the importance of T-cell epitopes in the generation of undesirable immunogenicity. In silico, in vitro, ex vivo and in vivo methods have therefore been developed that focus on identification of CD4+ T-cell epitopes in the sequence of therapeutic proteins. A case study of existing therapeutic proteins is presented to review these different approaches in order to assess their utility in predicting immunogenic potential.

High incidence of tuberculosis after alemtuzumab treatment in Hong Kong Chinese patients

Twenty-seven patients received the anti-CD52 monoclonal antibody alemtuzumab for hematologic malignancies and autoimmune cytopenias in a tuberculosis-endemic area. Seven patients developed mycobacterium tuberculosis (TB) infections (median: 4, 1-24, months from alemtuzumab). The actuarial 1- and 2-year incidence of TB was 31% and 45%. All patients had severe depression of lymphocyte counts subsequent to alemtuzumab treatment, and tuberculosis was extra-pulmonary in three cases. All seven patients had received prior chemotherapy/immunosuppression and tuberculosis had not occurred until alemtuzumab was administered. Patients receiving alemtuzumab in areas endemic for tuberculosis should have careful initial evaluation of TB exposure, so that prophylactic antibiotics might be administered. Tuberculosis reactivation should be considered for unexplained fever and symptoms after alemtuzumab treatment.

Campath 1-H treatment in patients with aggressive relapsing remitting multiple sclerosis

Campath 1-H (Alemtuzumab) is a humanised monoclonal antibody which targets the CD52 antigen, a low molecular weight glycoprotein present on the surface of most lymphocyte lineages, causing complement mediated lysis and rapid and prolonged T lymphocyte depletion. Following encouraging initial data from other centres we report our open label experience of using Campath 1-H as a treatment in aggressive relapsing multiple sclerosis in a consecutive series of 39 highly selected patients treated across three regional centres and followed for a mean of 1.89 years. The mean annualised relapse rate fell from 2.48 pre treatment to 0.19 post treatment with 29% of documented relapses observed in the 12 weeks following initial infusion. Mean change in EDSS was -0.36 overall and -0.15 in those patients completing > or =1 year of follow- up. Eighty-three per cent of patients had stable or improved disability following treatment. Infusion related side effects were common including rash, headache and pyrexia but were usually mild and self limiting. Transient worsening of pre-existing neurological deficits during infusion was observed in 3 patients. 12 patients developed biochemical evidence of autoimmune dysfunction, 2 patients developed thyroid disease and 1 patient autoimmune skin disease. We conclude that relapse rates fall following Campath 1-H. Whilst side effects were common these were normally self limiting or easily managed, suggesting Campath 1-H may be of use in the treatment of very active relapsing remitting multiple sclerosis.

A case of human T lymphotropic virus type I-associated synovial swelling

BACKGROUND

Human T lymphotropic virus type 1 (HTLV-I) is associated with T-cell activation, proliferation, and leukemogenesis. HTLV-I is the causative agent of adult T cell leukemia/lymphoma and is associated with myelopathy/tropical spastic paraparesis, uveitis, polymyositis, synovitis, thyroiditis, and bronchoalveolar pneumonia. Since T-cell abnormalities are present in those infected with HTLV-I, the clinical problems might result from abnormal immune function or from direct leukemic or lymphomatous cell infiltration of tissues in the body. Distinguishing between these potential causes might be difficult in patients with joint involvement since the clinical findings can be similar. Consequently, obtaining synovial tissue for analyses is likely to be helpful in determining which process is causing the clinical symptoms.

INVESTIGATIONS

Physical examination, comprehensive metabolic panel, complete blood counts, urinalysis, serological testing for rheumatoid factor, antinuclear antibodies, hepatitis, and cytomegalovirus; western blot for HTLV-I/II, lymphocyte phenotyping of peripheral blood, polymerase chain reaction, plain radiographic imaging, CT, MRI skin biopsy with immunohistochemical analysis, lymph node biopsy with immunohistochemical analysis, lymphocyte phenotyping of synovial fluid, synovial tissue biopsy with immunohistochemical analysis of synovial tissue, and synovial tissue culture.

DIAGNOSIS

HTLV-I infected synovial cells in conjunction with leukemic/lymphomatous infiltration of synovial tissue.

MANAGEMENT

Chemotherapy protocol using alemtuzumab.

Engineering and characterization of a mouse/human chimeric anti-phencyclidine monoclonal antibody

Previously, our laboratory produced a high affinity, anti-phencyclidine (PCP) murine monoclonal antibody (mAb6B5) that also binds other PCP-like arylcyclohexylamines. In this project, mAb6B5 is engineered into a mouse/human chimera (ch-mAb6B5) to assess the feasibility of developing it into a medication for PCP and PCP-like drug abuse. To create ch-mAb6B5, the light and heavy chain constant regions of mAb6B5 were replaced with human kappa and IgG(2) constant regions in order to decrease its potential immunogenicity in humans. To be an effective anti-PCP medication, ch-mAb6B5 must retain the critical immunochemical binding properties of mAb6B5. Expression vectors containing ch-mAb6B5 light chain and heavy chain cDNA were constructed and expressed in the murine myeloma cell line P3X63-Ag8.653. Immunoassays confirm that ch-mAb6B5 is indeed a chimera, composed of mAb6B5's PCP-binding variable domains and human kappa and IgG constant regions. Radioimmunoassays show that ch-mAb6B5 has the same drug-binding profile as mAb6B5. Ch-mAb6B5 and mAb6B5 bind PCP with a K(D) of 0.67 nM and 1.17 nM (respectively) and bind PCP-like arylcyclohexylamines 1-[1-(2-thienyl)cyclohexyl]piperidine and N-ethyl-1-phenylcyclohexylamine with similar specificity. Additionally, ch-mAb6B5 and mAb6B5 have the same calculated isoelectric points and molecular weights, critical properties in antigen-antibody interactions. These data demonstrate that mouse/human ch-mAb6B5, a "more human" version of murine mAb6B5, retains mAb6B5's unique drug-binding properties. This work supports our continued efforts to develop ch-mAb6B5 into a medication for PCP and PCP-like drug abuse - introducing the intriguing possibility of using a single therapeutic mAb for treating a class of abused drugs.

Immunogenicity screening in protein drug development

Most therapeutic proteins in clinical trials or on the market are, to a variable extent, immunogenic. Formation of antidrug antibodies poses a risk that should be assessed during drug development, as it possibly compromises drug safety and alters pharmacokinetics. The generation of these antibodies is critically dependent on the presence of T helper cell epitopes, which have classically been identified by in vitro methods using blood cells from human donors. As a novel development, in silico methods that identify T cell epitopes have been coming on line. These methods are relatively inexpensive and allow the mapping of epitopes from virtually all human leukocyte antigen molecules derived from a wide genetic background. In vitro assays remain important, but guided by in silico data they can focus on selected peptides and human leukocyte antigen haplotypes, thereby significantly reducing time and cost.

A low incidence of nontuberculous mycobacterial infections in pediatric hematopoietic stem cell transplantation recipients

Hematopoietic stem cell transplantation (HSCT) is being used to treat a wide spectrum of clinical disorders but opportunistic infection remains an important factor determining outcomes for these patients. Nontuberculous mycobacterial (NTM) infections are being reported more frequently in HSCT recipients and the incidence of NTM infections in adult recipients is reported to be 0.4%-4.9%. However, the incidence and severity of NTM infections are less well described in pediatric HSCT recipients. Centers for Disease Control and Prevention guidelines were used to define definite and probable NTM infection among 132 children undergoing 169 HSCT between January 2000 and December 2004 at our institution. NTM infection was diagnosed in 5 of 132 pediatric recipients (3.8%). There were no NTM infections diagnosed in the autologous HSCT recipients and the incidence of NTM in allogeneic HSCT recipients was 6.4% (95% confidence interval, 0.8-11.9). The mean age of the HSCT recipients who developed NTM infections was 8 years (range, 2-19 years); 3 were male and 2 were female. Four conditioning regimens included alemtuzumab and 3 had antithymocyte globulin. Of the 5 patients with NTM infections, 2 met the criteria for definite infection and 3 for probable infection. Of the 2 patients with definite NTM infection, 1 had disseminated disease with Mycobacterium avium complex and the other had Mycobacterium chelonae catheter-related bloodstream infection. The probable NTM infections were 1 skin infection with Mycobacterium kansasii and 2 lower respiratory tract infections with M avium complex. Median time to NTM infection was 115 days (range, 14-269 days) after HSCT. Two patients had graft-versus-host disease at the time of NTM infection. All 5 patients received 3-4 antimycobacterial drugs and all NTM infections resolved. In summary, the incidence of NTM infection in pediatric HSCT recipients appears similar to that described in adult HSCT recipients and the outcome appears to be excellent with the proper antibiotic therapy. The increased use of anti-T cell antibodies appears to be associated with an increased risk of NTM infections in pediatric HSCT recipients. Multicenter studies are needed to identify the risk factors, early diagnostic criteria, and optimal therapy.

Different mechanisms of Campath-1H-mediated depletion for CD4 and CD8 T cells in peripheral blood

It is assumed that complement and noncomplement-mediated mechanisms are similarly responsible for Campath-1H-mediated killing of all T-cell subtypes in vivo. However, the differing surface expression of CD52 on T-cell subtypes suggests that may not be the case. The purpose of this study is to determine the extent and mechanism of Campath-1H-mediated elimination of different T-cell subtypes in peripheral blood. Whole blood or lymphocytes isolated from peripheral blood of healthy volunteers by Ficoll density centrifugation were incubated with Campath-1H, with or without complement and/or serum, and the resultant T-cell elimination mechanisms studied. For CD4(+) T lymphocytes, 60% and 40% cell death and for CD8(+) T lymphocytes 23% and 77% cell death, in peripheral blood, was mediated by complement and noncomplement mediated mechanisms, respectively. CD4(+) T cells demonstrated approximately twice the amount of surface CD52 compared with CD8(+) T cells, consistent with primarily complement-mediated killing for CD4(+) T cells. Thus, peripheral blood supports differential and partial elimination of T-cell subtypes, suggesting that the complete T-cell elimination seen in transplant recipients is most likely due to contribution from other lymphoid organs.

Biologic therapies in rheumatology: lessons learned, future directions

During the past decade biologic therapies such as monoclonal antibodies and fusion proteins have revolutionized the management of rheumatic disease. By targeting key cytokines and immune cells biologics have provided more specific therapeutic interventions with less immunosuppression. Clinical use, however, has revealed that their theoretical simplicity hides a more complex reality. Efficacy, toxicity and even pharmacodynamic effects can deviate from those predicted, as poignantly illustrated by the catastrophic effects witnessed during the first-into-human administration of TGN1412. This review summarizes lessons gleaned from practical experience and discusses how these can inform future discovery and development of new biologic therapies for rheumatology.

CD52 ligation induces CD4 and CD8 down modulation in vivo and in vitro

To successfully induce donor-specific tolerance after immune depletion, it is essential to understand the residual and recovering immune system in the context of the depleting agent because the properties of such a recovering immune system differ based on the depleting agent used. In this study, we investigate the phenotypic and functional characteristics of T cells exposed to Campath-1H in vivo and in vitro. Recovering T cells demonstrated down modulated surface CD4 and CD8 (by flow cytometry) for up to 45 days after Campath-1H administration. Additionally, these T cells had an activated phenotype. To determine whether this CD4/8 down modulation was due to T-cell activation only or in part due to Campath-1H, whole blood from healthy volunteers was exposed to Campath-1H and the surviving lymphocytes isolated. Flow cytometry revealed a dose-dependent down modulation of CD4/8 without T-cell activation. Additionally, these Campath-1H-treated T cells were immunocompetent as indicated by increased surface CD69 and interleukin-2 (IL-2) production following stimulation by soluble anti-CD3 mAb. In conclusion, Campath-1H by itself down modulates surface CD4 and CD8 without activating T cells.

CD52 is a novel costimulatory molecule for induction of CD4+ regulatory T cells

We previously reported that 4C8 monoclonal antibody (mAb) provides a costimulatory signal to human CD4+ T cells and consequently induces regulatory T (Treg) cells, which are hypo-responsive and suppress the polyclonal response of bystander CD4+ cells in a contact-dependent manner. In this study, we identified the antigen of 4C8 mAb as CD52. Costimulation with Campath-1H, a humanized anti-CD52 mAb, also induced Treg cells. Anti-CD52-induced Treg cells suppressed the proliferation of both CD4+ and CD8+ T cells provided with polyclonal or allogeneic stimulation. When Treg cells were induced from Staphylococcal enterotoxin B (SEB) treated cells, they suppressed the response to SEB more efficiently than that to another superantigen, SEA. Furthermore, anti-CD52-induced Treg cells could be expanded by culture with IL-2 followed by CD52-costimulation, and co-injection of expanded Treg cells suppressed lethal xenogeneic graft versus host disease (GvHD) reactions in SCID mice caused by human peripheral blood mononuclear cells (PBMCs).

B CELL IMMUNOBIOLOGY IN DISEASE: Evolving Concepts from the Clinic

The pathogenic roles of B cells in autoimmune diseases occur through several mechanistic pathways that include autoantibodies, immune complexes, dendritic and T cell activation, cytokine synthesis, chemokine-mediated functions, and ectopic neolymphogenesis. Each of these pathways participate to different degrees in autoimmune diseases. The use of B cell-targeted and B cell subset-targeted therapies in humans is illuminating the mechanisms at work in a variety of human autoimmune diseases. In this review, we highlight some of these recent findings that provide insights into both murine models of autoimmunity and human autoimmune diseases.

Cytomegalovirus (CMV) infections and CMV-specific cellular immune reconstitution following reduced intensity conditioning allogeneic stem cell transplantation with Alemtuzumab

We studied the incidence and recurrence of Cytomegalovirus (CMV) infection and reactivation in 38 recipients of Alemtuzumab reduced intensity conditioning-stem cell transplantation, and used CMV-HLA tetramer studies to discover if these events correlated with recovery of circulating CMV-specific CD8+ T cells (cytotoxic T lymphocyte (CTLs)). The cumulative incidence of CMV infection was 60% at 1 year (95% CI, 45-78%) with a median reactivation time of 24 days (range 5-95 days). All patients with CMV reactivation received Ganciclovir or Foscarnet, and only one developed CMV disease. More strikingly, only 8/21 patients had relapse of CMV antigenemia. Tetramer analysis in 13 patients showed that 11 reconstituted CMV CTLs (7/11 by day 30 and 10/11 by day 90). The development of CMV infection was accompanied by a >5-fold rise of CMV CTLs. Recurrence of CMV infection occurred only in the patients who failed to generate a CTL response to the virus. Hence, recipients of SCT using Alemtuzumab-RIC are initially profoundly immunosuppressed and have a high incidence of early CMV reactivation. However, in the majority of patients, infection is transient, and antiviral T cell reconstitution is rapid. Monitoring with CMV-specific CTLs may help identify the subset of patients at risk from recurrent infection or disease.

Spectrum of infection, risk and recommendations for prophylaxis and screening among patients with lymphoproliferative disorders treated with alemtuzumab*

There is an increasing use of monoclonal antibodies in the treatment of haematological malignancies. Alemtuzumab (Campath-1H; Ilex Pharmaceuticals, San Antonio, TX, USA) is a monoclonal antibody reactive with the CD52 antigen used as first and second line therapy for two types of lymphoproliferative disorders: chronic lymphocytic leukaemia (CLL), and T-cell lymphomas [both peripheral (PTCL) and cutaneous (CTCL)]. With alemtuzumab therapy, viral, bacterial and fungal infectious complications are frequent, and may be life threatening. An understanding of the patients at highest risk and duration of risk are important in developing recommendations for empirical management, antimicrobial prophylaxis and targeted surveillance. This review discusses the infection risks associated with these lymphoproliferative disorders and their treatment, and provide detailed recommendations for screening and prophylaxis.

Tuberculosis due to Mycobacterium bovis after alemtuzumab administration

We describe a patient with relapsing B chronic lymphocytic leukemia who developed systemic bacille Calmette-Guérin infection (BCGitis) after administration of alemtuzumab (Campath-1H).