Depletion of CD52-positive cells inhibits the development of central nervous system autoimmune disease, but deletes an immune-tolerance promoting CD8 T-cell population. Implications for secondary autoimmunity of alemtuzumab in multiple sclerosis

Endoplasmic reticulum stress response in immune cells contributes to experimental autoimmune encephalomyelitis pathogenesis in rats

We examined the role of endoplasmic reticulum (ER) stress and the ensuing unfolded protein response (UPR) in the development of the central nervous system (CNS)-directed immune response in the rat model of experimental autoimmune encephalomyelitis (EAE). The induction of EAE with syngeneic spinal cord homogenate in complete Freund's adjuvant (CFA) caused a time-dependent increase in the expression of ER stress/UPR markers glucose-regulated protein 78 (GRP78), X-box-binding protein 1 (XBP1), C/EBP homologous protein (CHOP), and phosphorylated eukaryotic initiation factor 2α (eIF2α) in the draining lymph nodes of both EAE-susceptible Dark Agouti (DA) and EAE-resistant Albino Oxford (AO) rats. However, the increase in ER stress markers was more pronounced in AO rats. CFA alone also induced ER stress, but the effect was weaker and less sustained compared to full immunization. The ultrastructural analysis of DA lymph node tissue by electron microscopy revealed ER dilatation in lymphocytes, macrophages, and plasma cells, while immunoblot analysis of CD3-sorted lymph node cells demonstrated the increase in ER stress/UPR markers in both CD3+ (T cell) and CD3- (non-T) cell compartments. A positive correlation was observed between the levels of ER stress/UPR markers in the CNS-infiltrated mononuclear cells and the clinical activity of the disease. Finally, the reduction of EAE clinical signs by ER stress inhibitor ursodeoxycholic acid was associated with the decrease in the expression of mRNA encoding pro-inflammatory cytokines TNF and IL-1β, and encephalitogenic T cell cytokines IFN-γ and IL-17. Collectively, our data indicate that ER stress response in immune cells might be an important pathogenetic factor and a valid therapeutic target in the inflammatory damage of the CNS.

Clinical relevance of thymic and bone marrow outputs in multiple sclerosis patients treated with alemtuzumab

Thymic and bone marrow outputs were evaluated in 13 sequential samples of 68 multiple sclerosis patients who initiated alemtuzumab and were clinically followed for 48 months. Three months after alemtuzumab infusions, the levels of new T lymphocytes were significantly reduced, but progressively increased reaching the highest values at 36 months, indicating the remarkable capacity of thymic function recovery. Newly produced B cells exceeded baseline levels as early as 3 months after alemtuzumab initiation. Heterogeneous patterns of new T- and B-cell recovery were identified, but without associations with age, sex, previous therapies, development of secondary autoimmunity or infections, and disease re-emergence. Trial registration version 2.0-27/01/2016.

Single cell and spatial transcriptomic analyses reveal microglia-plasma cell crosstalk in the brain during Trypanosoma brucei infection

Human African trypanosomiasis, or sleeping sickness, is caused by the protozoan parasite Trypanosoma brucei and induces profound reactivity of glial cells and neuroinflammation when the parasites colonise the central nervous system. However, the transcriptional and functional responses of the brain to chronic T. brucei infection remain poorly understood. By integrating single cell and spatial transcriptomics of the mouse brain, we identify that glial responses triggered by infection are readily detected in the proximity to the circumventricular organs, including the lateral and 3rd ventricle. This coincides with the spatial localisation of both slender and stumpy forms of T. brucei. Furthermore, in silico predictions and functional validations led us to identify a previously unknown crosstalk between homeostatic microglia and Cd138+ plasma cells mediated by IL-10 and B cell activating factor (BAFF) signalling. This study provides important insights and resources to improve understanding of the molecular and cellular responses in the brain during infection with African trypanosomes.

The genealogy, methodology, similarities and differences of immune reconstitution therapies for multiple sclerosis and neuromyelitis optica

Immune reconstitution therapies (IRTs) are a type of short course procedure or pharmaceutical agent within the MS pharmacopeia. They emanate from oncology and induce transient incomplete lympho-ablation with or without myelo-ablation, resulting in potential prolonged immunomodulation. Thus, they provide significant prophylaxis from disease activity without retreatment. Modern IRT for autoimmunity encompasses a heterogeneous group of pulsed lympho- and non-myelo-ablative treatments designed to re-boot the adaptive immune system in a quasi-permanent manner - a re-induction of ontogeny. IRT is the extensive debulking of an auto-aggressive immune system to attempt to reach the Holy Grail of immune tolerance. This incomplete yet significant lympho-ablation induces lymphoproliferation, reduces pathogenic clonal cells, causes thymopoiesis and results in the induction of immune tolerance. Lympho-ablation with immune reconstitution can result in minimal residual autoimmunity. There is a resetting of the immune thermostat - i.e., the immunostat. IRTs have the potential to provide prolonged periods of disease inactivity without retreatment in part through the immunological results of their pulsatile lymphocyte depletion. It is vital to increase our understanding of how IRTs alter a patient's immune response to the antigenic target of the disease so that we can devise newer, more durable and safer forms of such agents. What common features do extant IRTs (i.e., stem cell transplant, alemtuzumab and oral cladribine) have to produce the durable therapeutic response without long term treatment in neuroimmunological diseases such as MS (multiple sclerosis) and NMOSD (neuromyelitis optica spectrum disorders)? Can we learn from these critical features to predict what other maneuvers or agents might effect similar clinical results with equal or greater efficacy and safety?

Autoimmune storm following alemtuzumab

Alemtuzumab has been associated with the emergence of secondary autoimmune diseases. We report a case of a patient with relapsing-remitting multiple sclerosis who developed a refractory immune thrombocytopaenia associated with vasculitis, myelofibrosis and later Guillain-Barré syndrome following alemtuzumab. The medical community should be aware of unusual and unexpected adverse events that may be associated with alemtuzumab, especially when occurring simultaneously in the same patient.

Loss of thymic function promotes EAE relapse in anti-CD52-treated mice

Anti-CD52 treatment creates a long-lasting CD4 T cell lymphopenia and reduces multiple sclerosis (MS) relapses in humans. In contrast, anti-CD52 therapy at disease onset more fully suppresses experimental autoimmune encephalomyelitis (EAE) in mice, and T cell repopulation is rapid. To test whether prolonged T cell lymphopenia promotes relapses, we thymectomized mice prior to EAE induction and anti-CD52 treatment. Thymectomy greatly reduced the number of recent thymic emigrant T cells and was associated with a prolonged reduction in CD4 T cells in peripheral blood. Two-thirds of thymectomized C57BL/6 mice had an EAE relapse post anti-CD52 treatment, while no surgery and sham surgery euthymic controls remained relapse-free. These data demonstrate that thymus function can alter the effectiveness of anti-CD52 treatment.

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Thymectomy significantly reduces the proportion of newly generated T cells.

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Thymectomy predisposes anti-CD52-treated mice to EAE relapse.

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Thymectomy-promoted EAE relapse in anti-CD52 treated mice is associated with weight decline and prolonged T cell lymphopenia.

IgG4-related autoimmune manifestations in Alemtuzumab-treated multiple sclerosis patients

We aimed to determine whether Alemtuzumab-induced immune reconstitution affects immunoglobulin and complement levels in the serum of Relapsing-Remitting Multiple Sclerosis (RRMS) patients. IgG4-levels were increased 24-months after treatment initiation compared to baseline levels in twenty-nine patients. Alemtuzumab-treated patients with the highest IgG4-levels were more prone to thyroid-related autoimmune manifestations and specific autoimmune adverse events such as Crohn's disease, Graves' disease, and hemolytic anemia. Compared to baseline, total IgG-levels showed a trend towards reduced levels following two-courses of Alemtuzumab, but no significant change of C3 and/or C4-levels was observed. In conclusion, monitoring of IgG4-levels can serve as a marker for secondary autoimmunity risk in multiple sclerosis patients treated with Alemtuzumab.

Product review on MAbs (alemtuzumab and ocrelizumab) for the treatment of multiple sclerosis

Traditionally, the management of active relapsing remitting MS was based on the, so-called, maintenance therapy, which is characterized by continuous treatment with particular disease modifying therapy (DMT), and a return of disease activity when the drug is discontinued. Another approach is characterized by a short treatment course of a DMT, which is hypothesized to act as an immune reconstitution therapy (IRT), with the potential to protect against relapses for years after a short course of treatment. Introduction of monoclonal antibodies in the treatment of MS has revolutionized MS treatment in the last decade. However, given the increasingly complex landscape of DMTs approved for MS, people with MS and neurologists are constantly faced with the question which DMT is the most appropriate for the given patient, a question we still do not have an answer to. In this product review, we will discuss the first DMT that acts as IRT, an anti-CD52 monoclonal antibody alemtuzumab and an anti CD20 monoclonal antibody, ocrelizumab that has the potential to act as an IRT, but is administered continuously. Special emphasis will be given on safety in the context of COVID-19 pandemics and vaccination strategies.

Antigen-specific tolerization in human autoimmunity: Inhibition of interferon-beta1a anti-drug antibodies in multiple sclerosis: A case report

BACKGROUND

Antigen-specific tolerance in auto-immune diseases is the goal for effective treatment with minimal side-effects. Whilst this is achievable in animal models, notably via intravenous delivery of the model-specific autoantigen following transient CD4 T cell depletion, specific multiple sclerosis autoantigens remain unproven. However, anti-drug antibodies to human therapeutic proteins represent a model human autoimmune condition, which may be used to examine immune-tolerance induction. Some people with MS (PwMS) on interferon-beta1a (IFNβ1a) develop neutralizing antibodies to IFNβ1a that do not disappear in repeated tests over years.

METHODS

One PwMS was recruited, as part of a planned phase IIa trial (n = 15), who had developed neutralizing antibodies to subcutaneous IFNβ1a. Mitoxantrone (12 mg/m²) was administered as a lymphocyte depleting agent followed by four days of (88 μg/day + three 132 μg/day) intravenous IFNβ1a. Subcutaneous IFNβ1a three times a week was maintained during follow-up. IFNβ1a neutralizing antibody responses in serum were measured during treatment and three-monthly for 12 months.

FINDINGS

One participant was recruited and, within 6 months of tolerization, the neutralizing antibodies were undetectable. The tolerization treatment was well tolerated. However, the study was terminated after the first enrolment, on ethical grounds, as treatment alternatives became available and the potential risks of mitoxantrone use increased.

INTERPRETATION

The data suggest that it may be possible to induce antigen-specific tolerance by providing tolerogenic antigen following transient immune depletion. Further studies are warranted.

FUNDING

The study was supported by an unrestricted research grant from Merck-Serono.

Effects of disease-modifying therapy on peripheral leukocytes in patients with multiple sclerosis

Modern disease-modifying therapies (DMTs) in multiple sclerosis (MS) have variable modes of action and selectively suppress or modulate the immune system. In this review, we summarize the predicted and intended as well as unwanted adverse effects on leukocytes in peripheral blood as a result of treatment with DMTs for MS. We link changes in laboratory tests to the possible therapeutic risks that include secondary autoimmunity, infections, and impaired response to vaccinations. Profound knowledge of the intended effects on leukocyte counts, in particular lymphocytes, explained by the mode of action, and adverse effects which may require additional laboratory and clinical vigilance or even drug discontinuation, is needed when prescribing DMTs to treat patients with MS.

Regulation of Monocyte Adhesion and Type I Interferon Signaling by CD52 in Patients With Systemic Sclerosis

OBJECTIVE

Systemic sclerosis (SSc) is characterized by dysregulation of type I interferon (IFN) signaling. CD52 is known for its immunosuppressive functions in T cells. This study was undertaken to investigate the role of CD52 in monocyte adhesion and type I IFN signaling in patients with SSc.

METHODS

Transcriptome profiles of circulating CD14+ monocytes from patients with limited cutaneous SSc (lcSSc), patients with diffuse cutaneous SSc (dcSSs), and healthy controls were analyzed by RNA sequencing. Levels of CD52, CD11b/integrin αΜ, and CD18/integrin β2 in whole blood were assessed by flow cytometry. CD52 expression was analyzed in relation to disease phenotype (early, lcSSc, dcSSc) and autoantibody profiles. The impact of overexpression, knockdown, and antibody blocking of CD52 was analyzed by gene and protein expression assays and functional assays.

RESULTS

Pathway enrichment analysis indicated an increase in adhesion- and type I IFN-related genes in monocytes from SSc patients. These cells displayed up-regulated expression of CD11b/CD18, reduced expression of CD52, and enhanced adhesion to intercellular adhesion molecule 1 and endothelial cells. Changes in CD52 expression were consistent with the SSc subtypes, as well as with immunosuppressive treatments, autoantibody profiles, and monocyte adhesion properties in patients with SSc. Overexpression of CD52 led to decreased levels of CD18 and monocyte adhesion, while knockdown of CD52 increased monocyte adhesion. Experiments with the humanized anti-CD52 monoclonal antibody alemtuzumab in blood samples from healthy controls increased monocyte adhesion and CD11b/CD18 expression, and enhanced type I IFN responses. Monocytic CD52 expression was up-regulated by interleukin-4 (IL-4)/IL-13 via the STAT6 pathway, and was down-regulated by lipopolysaccharide and IFNs α, β, and γ in a JAK1 and histone deacetylase IIa (HDAC IIa)-dependent manner.

CONCLUSION

Down-regulation of the antiadhesion CD52 antigen in CD14+ monocytes represents a novel mechanism in the pathogenesis of SSc. Targeting of the IFN-HDAC-CD52 axis in monocytes might represent a new therapeutic option for patients with early SSc.

New Algorithms Improving PML Risk Stratification in MS Patients Treated With Natalizumab

Overview: We assessed the role of age and disease activity as new factors contributing to establish the risk of progressive multifocal leucoencephalopathy in multiple sclerosis patients treated with natalizumab in 36 University Hospitals in Europe. We performed the study in 1,307 multiple sclerosis patients (70.8% anti-John Cunninghan virus positive antibodies) treated with natalizumab for a median time of 3.28 years. Epidemiological, clinical, and laboratory variables were collected. Lipid-specific IgM oligoclonal band status was available in 277 patients. Factors associated with progressive multifocal leucoencephalopathy onset were explored by uni- and multivariate logistic regression. Results: Thirty-five patients developed progressive multifocal leucoencephalopathy. The multivariate analysis identified anti-John Cunninghan virus antibody indices and relapse rate as the best predictors for the onset of this serious opportunistic infection in the whole cohort. They allowed to stratify progressive multifocal leucoencephalopathy risk before natalizumab initiation in individual patients [area under the curve (AUC) = 0.85]. The risk ranged from <1/3,300 in patients with anti-John Cunninghan virus antibody indices <0.9 and relapse rate >0.5, to 1/50 in the opposite case. In patients with lipid-specific IgM oligoclonal bands assessment, age at natalizumab onset, anti-John Cunninghan virus antibody indices, and lipid-specific IgM oligoclonal band status predicted progressive multifocal leucoencephalopathy risk (AUC = 0.92). The absence of lipid-specific IgM oligoclonal bands was the best individual predictor (OR = 40.94). The individual risk ranged from <1/10,000 in patients younger than 45 years at natalizumab initiation, who showed anti John Cunningham virus antibody indices <0.9 and lipid-specific IgM oligoclonal bands to 1/33 in the opposite case. Conclusions: In a perspective of personalized medicine, disease activity, anti-lipid specific IgM oligoclonal bands, anti Jonh Cunninghan virus antibody levels, and age can help tailor natalizumab therapy in multiple sclerosis patients, as predictors of progressive multifocal leucoencephalopathy.

Cardiac sarcoidosis requiring ICD placement and immune thrombocytopenia following alemtuzumab treatment for multiple sclerosis

Alemtuzumab, an effective disease-modifying therapy for multiple sclerosis, carries a significant risk of secondary autoimmunity. We present a case of cardiac sarcoidosis and immune thrombocytopenia diagnosed in an MS patient two years after completing alemtuzumab treatment. We hypothesize that alemtuzumab-induced changes to the T regulatory cell population may be implicated in the development of sarcoidosis in MS patients.

Mitigating alemtuzumab-associated autoimmunity in MS: A "whack-a-mole" B-cell depletion strategy

Objective

To determine whether the punctuated administration of low-dose rituximab, temporally linked to B-cell hyperrepopulation (defined when the return of CD19⁺ B cells approximates 40%–50% of baseline levels as measured before alemtuzumab treatment inception), can mitigate alemtuzumab-associated secondary autoimmunity.

Methods

In this hypothesis-driven pilot study, 10 patients received low-dose rituximab (50–150 mg/m²), a chimeric anti-CD20 monoclonal antibody, after either their first or second cycles of alemtuzumab. These patients were then routinely assessed for the development of autoimmune disorders and safety signals related to the use of dual monoclonal antibody therapy.

Results

Five patients received at least 1 IV infusion of low-dose rituximab, following alemtuzumab therapy, with a mean follow-up of 41 months. None of the 5 patients developed secondary autoimmune disorders. An additional 5 patients with follow-up over less than 24 months received at least 1 infusion of low-dose rituximab treatment following alemtuzumab treatment. No secondary autoimmune diseases were observed.

Conclusions

An anti-CD20 “whack-a-mole” B-cell depletion strategy may serve to mitigate alemtuzumab-associated secondary autoimmunity in MS by reducing the imbalance in B- and T-cell regulatory networks during immune reconstitution. We believe that these observations warrant further investigation.

Classification of evidence

This study provides Class IV evidence that for people with MS, low-dose rituximab following alemtuzumab treatment decreases the risk of alemtuzumab-associated secondary autoimmune diseases.

Anti-CD52 blocks EAE independent of PD-1 signals and promotes repopulation dominated by double-negative T cells and newly generated T and B cells

Lymphocyte depletion using anti-CD52 antibody effectively reduces relapses of multiple sclerosis (MS). To begin to understand what mechanisms might control this outcome, we examined the effect of a murine-CD52-specific mAb on the depletion and repopulation of immune cells in mice with experimental autoimmune encephalomyelitis (EAE), a model of MS. We tested whether the tolerance-promoting receptor programmed cell death protein-1 (PD-1) is required for disease remission post anti-CD52, and found that PD-1-deficient mice with a more severe EAE were nevertheless effectively treated with anti-CD52. Anti-CD52 increased the proportions of newly generated T cells and double-negative (DN) T cells while reducing newly generated B cells; the latter effect being associated with a higher expression of CD52 by these cells. In the longer term, anti-CD52 caused substantial increases in the proportion of newly generated lymphocytes and DN T cells in mice with EAE. Thus, the rapid repopulation of lymphocytes from central lymphoid organs post anti-CD52 may limit further disease. Furthermore, these data identify DN T cells, a subset with immunoregulatory potential, as a significant hyperrepopulating subset following CD52-mediated depletion.

Establishing immune scoring model based on combination of the number, function, and phenotype of lymphocytes

Background: Quantitatively assessing host immunity remains a challenge in clinical practice.

Results: Most parameters in lymphocyte number, function and phenotype were correlated with age. The reference ranges of these parameters were established in four age groups (children, adolescents, adults, and elders). The numbers of CD4⁺ T cells, CD8⁺ T cells, B cells, but not NK cells, were negatively correlated with age. However, the function of CD4⁺ T cells, CD8⁺ T cells and NK cells was positively correlated with age. The expression of CD28 on T cells gradually decreased with increasing age and was negatively correlated with their function. An opposite phenomenon was observed in the expressions of HLA-DR and CD45RO on T cells. An immune scoring model was established by using 8 parameters (CD4⁺ T cell number × function, CD28⁺CD4⁺ T cell number, HLA-DR⁺CD4⁺ T cell number, CD45RO⁺CD4⁺ T cell number, CD8⁺ T cell number × function, CD28⁺CD8⁺ T cell number, HLA-DR⁺CD8⁺ T cell number, NK cell number × function) from the results of lymphocyte number, function, and phenotype. This immune scoring model showed sensitivities of 70% and 71.4% in determining hyper-immune and hypo-immune status, respectively.

Conclusions: An immune scoring model based on combination of lymphocyte number, function, and phenotype shows potential value in quantitatively assessing host immunity.

Methods: 261 healthy individuals aged 1 to 82 years were recruited from Tongji Hospital. The number, function, and phenotype of CD4⁺ T cells, CD8⁺ T cells and NK cells were simultaneously determined.

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.

Event-Driven Immunoprofiling Predicts Return of Disease Activity in Alemtuzumab-Treated Multiple Sclerosis

Background: Alemtuzumab is a highly effective drug for the treatment of multiple sclerosis (MS), characterized by specific patterns of depletion and repopulation. As an induction-like treatment concept, two mandatory infusion courses can inhibit long-term disease activity in the majority of patients, and additional courses can successfully manage subsequent re-emergence of disease activity. Currently, there are no biomarkers to identify patients with re-emergent disease activity requiring retreatment.

Methods: In this study, we systematically characterized 16 MS patients commencing alemtuzumab. Clinical parameters, MRI and detailed immunoprofiling were conducted every 3 months for up to 84 months.

Results: Alemtuzumab led to significant decrease in clinical disease activity in all evaluated patients. Nine out of 16 patients presented with no evidence of disease activity (NEDA)-3 up to 84 months (“complete-responder”), while 7 patients demonstrated clinical or/and subclinical MRI disease activity and received alemutzumab retreatment (“partial-responder”). In both response categories, all T- and B-cell subsets were markedly depleted after alemtuzumab therapy. In particular, absolute numbers of Th1 and Th17 cells were markedly decreased and remained stable below baseline levels—this effect was particularly pronounced in complete-responders. While mean cell numbers did not differ significantly between groups, analysis of event-driven immunoprofiling demonstrated that absolute numbers of Th1 and Th17 cells showed a reproducible increase starting 6 months before relapse activity. This change appears to predict emergent disease activity when compared with stable disease.

Conclusion: Studies with larger patient populations are needed to confirm that frequent immunoprofiling may assist in evaluating clinical decision-making of alemtuzumab retreatment.

Risks and risk management in modern multiple sclerosis immunotherapeutic treatment

In recent years, there has been a paradigm shift in the treatment of multiple sclerosis (MS) owing to the approval of a number of new drugs with very distinct mechanisms of action. All approved disease-modifying drugs primarily work directly on the immune system. However, the identification of an ‘optimal choice’ for individual patients with regard to treatment efficacy, treatment adherence and side-effect profile has become increasingly complex including conceptual as well as practical considerations. Similarly, there are peculiarities and specific requirements with regard to treatment monitoring, especially in relation to immunosuppression, the development of secondary immune-related complications, as well as the existence of drug-specific on- and off-target effects. Both classical immunosuppression and selective immune interventions generate a spectrum of potential therapy-related complications. This article provides a comprehensive overview of available immunotherapeutics for MS and their risks, detailing individual mechanisms of action and side-effect profiles. Furthermore, practical recommendations for patients treated with modern MS immunotherapeutics are provided.

Immune thrombocytopenia in alemtuzumab-treated MS patients: Incidence, detection, and management

Background:

Alemtuzumab is a highly effective therapy for relapsing-remitting multiple sclerosis (RRMS), and immune thrombocytopenia (ITP) has been identified as a risk.

Objective:

To examine ITP incidence, treatment, and outcomes during the clinical development of alemtuzumab for RRMS and discuss postmarketing experience outside clinical trials.

Methods:

CAMMS223 and Comparison of Alemtuzumab and Rebif^® Efficacy in Multiple Sclerosis (CARE-MS) I and II investigated two annual courses of alemtuzumab 12 mg (or 24 mg in CAMMS223/CARE-MS II) versus subcutaneous interferon beta-1a three times per week. Patients completing core studies could enroll in an extension. Monthly monitoring for ITP continued until 48 months after the last alemtuzumab infusion.

Results:

Of 1485 alemtuzumab-treated MS patients in the clinical development program, 33 (2.2%) developed ITP (alemtuzumab 12 mg, 24 [2.0%]; alemtuzumab 24 mg, 9 [3.3%]) over median 6.1 years of follow-up after the first infusion; most had a sustained response to first-line ITP therapy with corticosteroids, platelets, and/or intravenous immunoglobulin. All cases occurred within 48 months of the last alemtuzumab infusion. Postmarketing surveillance data suggest that the ITP incidence is not higher in clinical practice than in clinical trials.

Conclusion:

Alemtuzumab-associated ITP occurs in approximately 2% of patients and is responsive to therapy. Careful monitoring is key for detection and favorable outcomes.

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.

Efficacy and Safety of the Newer Multiple Sclerosis Drugs Approved Since 2010

Multiple sclerosis treatment faces tremendous changes as a result of the approval of new medications. The new medications have differing safety considerations and risks after long-term treatment, which are important for treating physicians to optimize and individualize multiple sclerosis care. Since the approval of the first multiple sclerosis capsule, fingolimod, the armamentarium of multiple sclerosis therapy has grown with the orally available medications dimethyl fumarate and teriflunomide. Fingolimod is mainly associated with cardiac side effects, dimethyl fumarate with bowel symptoms. Several reports about progressive multifocal leukoencephalopathy as a result of dimethyl fumarate or fingolimod therapy raised the awareness of fatal opportunistic infections. Alemtuzumab, a CD52-depleting antibody, is highly effective in reducing relapses but leads to secondary immunity with mainly thyroid disorders in about 30% of patients. Development of secondary B-cell-mediated disease might also be a risk of this antibody. The follow-up drug of the B-cell-depleting antibody rituximab, ocrelizumab, is mainly associated with infusion-related reactions; long-term data are scarce. The medication daclizumab high yield process, acting via the activation of CD56^bright natural killer cells, can induce the elevation of liver function enzymes, but also fulminant liver failure has been reported. Therefore, daclizumab has been retracted from the market. Long-term data on the purine nucleoside cladribine in MS therapy, recently authorized in the European Union, have been acquired during the long-term follow-up of the cladribine studies. The small molecule laquinimod is currently under development. We review data of clinical trials and their extensions regarding long-term efficacy and side effects, which might be associated with long-term treatment.

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.

Immunomodulation in multiple sclerosis: promises and pitfalls

Multiple sclerosis (MS) afflicts about 2.5 million people globally and poses a major personal and socioeconomic burden. The recognition of MS as an inflammatory disease, characterized by infiltration of immune cells into the central nervous system, has spurred research into the autoimmune etiology of the condition and has provided the rationale for its treatment through immunomodulation. Experience with immunotherapies in MS to date has suggested a disparity between the observed immune cell infiltration and the progressive loss of neurons. However, recent clinical efforts are providing new insights into progressive MS that once again place the immune system at center stage. This article reviews the main mechanisms of MS immunopathogenesis, and the benefits, risks and challenges of immunomodulatory treatments for the disease.

Decreased platelet number in multiple sclerosis during alemtuzumab infusion: a common, transient and clinically silent phenomenon

Background

The cause and clinical significance of the transient decrease in platelet (PLT) count observed in relapsing remitting multiple sclerosis (RRMS) during alemtuzumab administration remain undefined. The aim of this study was to analyse the kinetics and clinical relevance of early onset thrombocytopaenia in alemtuzumab-treated RRMS.

Methods

A total of 26 patients with RRMS were included in a longitudinal study. Blood samples were collected immediately before the first alemtuzumab infusion (D0), and after 3 days (D3), 28 days (D28) and 49 days (D49). PLT, red blood cell (RC), leucocyte and lymphocyte counts, haemoglobin (Hb) concentration and haematocrit (Htc) were measured. Patients with MS were clinically evaluated every day of drug infusion and then at D28 and D49 to verify the presence of signs or symptoms suggestive of thrombocytopaenia.

Results

PLT number significantly decreased at D3 (p < 0.005) and was associated with a decrease in RC count (r: 0.53, p < 0.01), Hb (r: 0.42, p = 0.05) and Htc (r: 0.53, p < 0.01). A progressive reversion of PLT number to normal values was observed at D28 and D49. A mild thrombocytopaenia was observed in 12 patients (46.2%), 8 of which (66.6%) had PLT nadir values at D3, and 4 (33.3%) at D28. No sign or symptom suggestive of thrombocytopaenia was observed. A strong correlation between pretreatment and nadir PTL counts (r: 0.59, p < 0.005) was observed; indeed, mild thrombocytopaenia was observed more frequently in these patients with a baseline PTL count lower than 230 × 10⁹/L (83.3% versus 42.9%, p < 0.05).

Conclusions

The early PLT decrease in alemtuzumab-treated patients is transient, mild, not associated with clinically relevant events and is probably related to the cytokine-released syndrome. Notwithstanding this, our findings suggest the opportunity for PLT monitoring during infusion and in the following 2 months, since a decrease in PLT count may occur.

CD4+ CD52lo T-cell expression contributes to the development of systemic lupus erythematosus

The cell-surface glycoprotein CD52 is widely expressed in lymphocytes. CD4⁺CD52^hi T cells are functioning suppressor CD4⁺T cells. We investigated the role of the immune regulation of CD4⁺CD52 T cells in systemic lupus erythematosus (SLE). CD4⁺CD52^lo T cells were increased in SLE patients, in positive correlation with SLEDAI, anti-ds-DNA antibody, and IgG concentration. Circulating follicular helper-like T cells (Tfh-like cells) were also increased in SLE, in positive correlation with CD4⁺CD52^lo T cells. Chemokine receptor 8 (CCR8) expression in CD4⁺CD52^lo T cells was increased. In vitro experiments using CD4 T cells of SLE patients showed that thymus and activation-regulated chemokine (TARC), a ligand of CCR8, contributed to the development of CD4⁺CD52^hi T cells into CD4⁺CD52^lo T cells. Our findings suggest that CD4+CD52lo T-cell upregulation is involved in the production of pathogens by autoantibodies, and TARC may contribute to the development of SLE through an aberrant induction of CD4⁺CD52^lo T cells.

Monoclonal Antibodies in Preclinical EAE Models of Multiple Sclerosis: A Systematic Review

Monoclonal antibodies (mAb) are promising therapeutics in multiple sclerosis and multiple new candidates have been developed, hence increasing the need for some agreement for preclinical mAb studies. We systematically analyzed publications of experimental autoimmune encephalomyelitis (EAE) studies showing effects of monoclonal antibodies. A PubMed search retrieved 570 records, out of which 122 studies with 253 experiments were eligible based on experimental design, number of animals and presentation of time courses of EAE scores. Analysis of EAE models, treatment schedules, single and total doses, routes of administration, and onset of treatment from pre-immunization up to 35 days after immunization revealed high heterogeneity. Total doses ranged from 0.1 to 360 mg/kg for observation times of up to 35 days after immunization. About half of experiments (142/253) used total doses of 10-70 mg/kg. Employing this range, we tested anti-Itga4 as a reference mAb at varying schedules and got no, mild or substantial EAE-score reductions, depending on the mouse strain and onset of the treatment. The result agrees with the range of outcomes achieved in 10 reported anti-Itga4 experiments. Studies comparing low and high doses of various mAbs or early vs. late onset of treatment did not reveal dose-effect or timing-effect associations, with a tendency towards better outcomes with preventive treatments starting within the first week after immunization. The systematic comparison allows for extraction of some "common" design characteristics, which may be helpful to further assess the efficacy of mAbs and role of specific targets in preclinical models of multiple sclerosis.

Interpreting Lymphocyte Reconstitution Data From the Pivotal Phase 3 Trials of Alemtuzumab

Importance

Alemtuzumab, a CD52-depleting monoclonal antibody, effectively inhibits relapsing multiple sclerosis (MS) but is associated with a high incidence of secondary B-cell autoimmunities that limit use. These effects may be avoided through control of B-cell hyperproliferation.

Objective

To investigate whether the data describing the effect of alemtuzumab on lymphocyte subsets collected during the phase 3 trial program reveal mechanisms explaining efficacy and the risk for secondary autoimmunity with treatment of MS.

Design, Setting, and Participants

Lymphocyte reconstitution data from regulatory submissions of the pivotal Comparison of Alemtuzumab and Rebif Efficacy in Multiple Sclerosis I and II (CARE-MS I and II) trials were obtained from the European Medicines Agency via Freedom of Information requests. Data used in this study were reported from June 22 to October 12, 2016.

Main Outcomes and Measures

Tabulated data from T- and B-lymphocyte subset analysis and antidrug antibody responses were extracted from the supplied documents.

Results

Alemtuzumab depleted CD4+ T cells by more than 95%, including regulatory cells (-80%) and CD8+ T cells (>80% depletion), which remained well below reference levels throughout the trials. However, although CD19+ B cells were initially also depleted (>85%), marked (180% increase) hyperrepopulation of immature B cells occurred with conversion to mature B cells over time. These lymphocyte kinetics were associated with rapid development of alemtuzumab-binding and -neutralizing antibodies and subsequent occurrence of secondary B-cell autoimmunity. Hyperrepopulation of B cells masked a marked, long-term depletion of CD19+ memory B cells that may underpin efficacy in MS.

Conclusions and Relevance

Although blockade of memory T and B cells may limit MS, rapid CD19+ B-cell subset repopulation in the absence of effective T-cell regulation has implications for the safety and efficacy of alemtuzumab. Controlling B-cell proliferation until T-cell regulation recovers may limit secondary autoimmunity, which does not occur with other B-cell-depleting agents.

Impact of aging immune system on neurodegeneration and potential immunotherapies

The interaction between the nervous and immune systems during aging is an area of avid interest, but many aspects remain unclear. This is due, not only to the complexity of the aging process, but also to a mutual dependency and reciprocal causation of alterations and diseases between both the nervous and immune systems. Aging of the brain drives whole body systemic aging, including aging-related changes of the immune system. In turn, the immune system aging, particularly immunosenescence and T cell aging initiated by thymic involution that are sources of chronic inflammation in the elderly (termed inflammaging), potentially induces brain aging and memory loss in a reciprocal manner. Therefore, immunotherapeutics including modulation of inflammation, vaccination, cellular immune therapies and "protective autoimmunity" provide promising approaches to rejuvenate neuroinflammatory disorders and repair brain injury. In this review, we summarize recent discoveries linking the aging immune system with the development of neurodegeneration. Additionally, we discuss potential rejuvenation strategies, focusing aimed at targeting the aging immune system in an effort to prevent acute brain injury and chronic neurodegeneration during aging.

Alemtuzumab in the long-term treatment of relapsing-remitting multiple sclerosis: an update on the clinical trial evidence and data from the real world

Alemtuzumab is a humanized monoclonal antibody approved for the treatment of relapsing-remitting multiple sclerosis (RRMS), given as two annual courses on five consecutive days at baseline and on three consecutive days 12 months later. Here we provide an update on the long-term efficacy and safety of alemtuzumab in RRMS, including real-world experience, and advances in our understanding of its mechanism of action. Recent data from the phase II/III extension study have demonstrated that alemtuzumab reduces relapse rates, disability worsening, and the rate of brain volume loss over the long term, with many patients achieving no evidence of disease activity. In high proportions of patients, preexisting disability remained stable or improved. Alemtuzumab is associated with a consistent safety profile over the long term, with no new safety signals emerging and the overall annual incidence of reported adverse events decreasing after the first year on treatment. Acyclovir prophylaxis reduces herpetic infections, and monitoring has been shown to mitigate the risk of autoimmune adverse events, allowing early detection and overall effective management. Data from clinical practice and ongoing observational studies are providing additional information on the real-world use of alemtuzumab. Recent evidence on the mechanism of action of alemtuzumab indicates that in addition to its previously known effects of inducing depletion and repopulation of T and B lymphocytes, it also results in a relative increase of cells with memory and regulatory phenotypes and a decrease in cells with a proinflammatory signature, and may further promote an immunoregulatory environment through an impact on other innate immune cells (e.g. dendritic cells) that play a role in MS. These effects may allow preservation of innate immunity and immunosurveillance. Together, these lines of evidence help explain the durable clinical efficacy of alemtuzumab, in the absence of continuous treatment, in patients with RRMS.

Direct targeting of cancer cells with antibodies: What can we learn from the successes and failure of unconjugated antibodies for lymphoid neoplasias?

Following approval in 1997 of the anti-CD20 antibody rituximab for the treatment of B-NHL and CLL, many other unconjugated IgG1 MAbs have been tested in pre-clinical and clinical trials for the treatment of lymphoid neoplasms. Relatively few have been approved however and these are directed against a limited number of target antigens (CD20, CD52, CCR4, CD38, CD319). We review here the known biological properties of these antibodies and discuss which factors may have led to their success or may, on the contrary, limit their clinical application. Common factors of the approved MAbs are that the target antigen is expressed at relatively high levels on the neoplastic targets and their mechanism of action is mostly immune-mediated. Indeed most of these MAbs induce ADCC and phagocytosis by macrophages, and many also activate complement, leading to target cell lysis. In contrast direct cell death induction is not a common feature but may enhance efficacy in some cases. Interestingly, a key factor for the success of several MAbs appears to be their capacity to skew immunity towards an anti-tumour mode, by inhibiting/depleting suppressor cells and/or activating immune cells within the microenvironment, independently of FcγRs. We also expose here some of the strategies employed by industry to expand the clinical use of these molecules beyond their original indication. Interestingly, due to the central role of lymphocytes in the control of the immune response, several of the antibodies are now successfully used to treat many different autoimmune diseases and have also been formally approved for some of these new indications. There is little doubt that this trend will continue and that the precise mechanisms of therapeutic MAbs will be further dissected and better understood in the context of both tumour immunology and autoimmunity.

Both cladribine and alemtuzumab may effect MS via B-cell depletion

Objective:

To understand the efficacy of cladribine (CLAD) treatment in MS through analysis of lymphocyte subsets collected, but not reported, in the pivotal phase III trials of cladribine and alemtuzumab induction therapies.

Methods:

The regulatory submissions of the CLAD Tablets Treating Multiple Sclerosis Orally (CLARITY) (NCT00213135) cladribine and Comparison of Alemtuzumab and Rebif Efficacy in Multiple Sclerosis, study one (CARE-MS I) (NCT00530348) alemtuzumab trials were obtained from the European Medicine Agency through Freedom of Information requests. Data were extracted and statistically analyzed.

Results:

Either dose of cladribine (3.5 mg/kg; 5.25 mg/kg) tested in CLARITY reduced the annualized relapse rate to 0.16–0.18 over 96 weeks, and both doses were similarly effective in reducing the risk of MRI lesions and disability. Surprisingly, however, T-cell depletion was rather modest. Cladribine 3.5 mg/kg depleted CD4⁺ cells by 40%–45% and CD8⁺ cells by 15%–30%, whereas alemtuzumab suppressed CD4⁺ cells by 70%–95% and CD8⁺ cells by 47%–55%. However, either dose of cladribine induced 70%–90% CD19⁺ B-cell depletion, similar to alemtuzumab (90%). CD19⁺ cells slowly repopulated to 15%–25% of baseline before cladribine redosing. However, alemtuzumab induced hyperrepopulation of CD19⁺ B cells 6–12 months after infusion, which probably forms the substrate for B-cell autoimmunities associated with alemtuzumab.

Conclusions:

Cladribine induced only modest depletion of T cells, which may not be consistent with a marked influence on MS, based on previous CD4⁺ T-cell depletion studies. The therapeutic drug-response relationship with cladribine is more consistent with lasting B-cell depletion and, coupled with the success seen with monoclonal CD20⁺ depletion, suggests that B-cell suppression could be the major direct mechanism of action.

Memory B Cells are Major Targets for Effective Immunotherapy in Relapsing Multiple Sclerosis

Although multiple sclerosis (MS) is considered to be a CD4, Th17-mediated autoimmune disease, supportive evidence is perhaps circumstantial, often based on animal studies, and is questioned by the perceived failure of CD4-depleting antibodies to control relapsing MS. Therefore, it was interestingly to find that current MS-treatments, believed to act via T cell inhibition, including: beta-interferons, glatiramer acetate, cytostatic agents, dimethyl fumarate, fingolimod, cladribine, daclizumab, rituximab/ocrelizumab physically, or functionally in the case of natalizumab, also depleted CD19+, CD27+ memory B cells. This depletion was substantial and long-term following CD52 and CD20-depletion, and both also induced long-term inhibition of MS with few treatment cycles, indicating induction-therapy activity. Importantly, memory B cells were augmented by B cell activating factor (atacicept) and tumor necrosis factor (infliximab) blockade that are known to worsen MS. This creates a unifying concept centered on memory B cells that is consistent with therapeutic, histopathological and etiological aspects of MS.