Human peripheral blood mononuclear cells exhibit heterogeneous CD52 expression levels and show differential sensitivity to alemtuzumab mediated cytolysis

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.

CD52-negative T cells predict acute graft-versus-host disease after an alemtuzumab-based conditioning regimen

Allogeneic haematopoietic stem cell transplantation (HSCT) after a reduced-intensity conditioning (RIC) regimen with fludarabine, melphalan and alemtuzmab is an effective therapy for haematological malignancies. Alemtuzumab, a monoclonal antibody against CD52, a glycosylphosphatidylinositol-anchor-bound surface protein on lymphocytes, depletes T cells to prevent graft-versus-host disease (GVHD). Despite this, acute and chronic GVHD (a/cGVHD) remain life-threatening complications after HSCT. The aim of the present study was to identify parameters to predict GVHD. In 69 patients after HSCT, T-cell subsets were functionally analysed. Reconstitution of CD52^neg T cells and CD52^neg regulatory T cells (Tregs) correlated with onset, severity and clinical course of aGVHD. Patients with aGVHD showed significantly lower levels of CD52^pos T cells compared to patients with cGVHD or without GVHD (P < 0·001). Analysis of T-cell reconstitution revealed a percentage of <40% of CD52^pos CD4^pos T cells or CD52^pos Tregs at day +50 as a risk factor for the development of aGVHD. In contrast, CD52^neg Tregs showed significant decreased levels of glycoprotein A repetitions predominant (GARP; P < 0·001), glucocorticoid-induced TNFR-related protein (GITR; P < 0·001), chemokine receptor (CXCR3; P = 0·023), C-C chemokine receptor type 5 (CCR5; P = 0·004), but increased levels of immunoglobulin-like transcript 3 (ILT3; P = 0·001), as well as a reduced suppressive capacity. We conclude that reconstitution of CD52^neg T cells and CD52^neg Tregs is a risk factor for development of aGVHD.

Pregnancy outcomes and postpartum relapse rates in women with RRMS treated with alemtuzumab in the phase 2 and 3 clinical development program over 16 years

BACKGROUND

Relapsing-remitting multiple sclerosis (RRMS) is frequently diagnosed in women of reproductive age. Because the use of disease-modifying therapies (DMTs) early in the disease course is increasing, it is important to evaluate the safety of DMTs in pregnant women and their developing fetuses. Alemtuzumab, approved for the treatment of relapsing forms of MS, is administered as 2 courses of 12 mg/day on 5 consecutive days at baseline and on 3 consecutive days 12 months later. Alemtuzumab is eliminated from the body within approximately 30 days after administration; it is recommended that women of childbearing potential use effective contraception during and for 4 months after treatment. Here, we report pregnancy outcomes in alemtuzumab-treated women from the phase 2 and 3 clinical development program over 16 years.

METHODS

We followed 972 women who had alemtuzumab in phase 2 (CAMMS223 [NCT00050778]) and phase 3 (CARE-MS I [NCT00530348], CARE-MS II [NCT00548405]) studies, and/or in 2 consecutive extension studies (NCT00930553; NCT02255656 [TOPAZ]). In the extension studies, patients could receive additional alemtuzumab (12 mg/day on 3 days; ≥12 months apart) as needed for disease activity. All women who received alemtuzumab in the clinical development program were included. Pregnant or lactating patients were followed up for safety.

RESULTS

As of November 26, 2018, 264 pregnancies occurred in 160 alemtuzumab-treated women, with a mean age at conception of 32.6 years, and mean time from last alemtuzumab dose to conception of 35.9 months. Of the 264 pregnancies, 233 (88%) were completed, 11 (4%) were ongoing, and 20 (8%) had unknown outcomes; 16 (6%) conceptions occurred within 4 months, and 5 conceptions within 1 month of the last alemtuzumab dose. Of the 233 completed pregnancies with known outcomes, there were 155 (67%) live births with no congenital abnormalities or birth defects, 52 (22%) spontaneous abortions, 25 (11%) elective abortions, and 1 (0.4%) stillbirth. Maternal age was associated with an increased risk of spontaneous abortion in alemtuzumab-treated patients (<35 years: 15%; ≥35 years: 37%; relative risk [RR], 2.46 [95% CI: 1.53-3.95], p=0.0002). Risk of spontaneous abortion was not increased in patients becoming pregnant ≤4 months versus >4 months since alemtuzumab exposure (19% vs 23%; RR, 1.08 [95% CI: 0.41-2.85], p=0.88). Autoimmune thyroid adverse events did not increase risk for spontaneous abortion (patients with vs without thyroid adverse events, 23.7% vs 21.3%; RR, 1.11 [95% CI: 0.69-1.80], p=0.75). Annualized relapse rate was 0.10 and 0.12 in the 2 years prior to pregnancy (post alemtuzumab), and was 0.22, 0.12, and 0.12 in each of the first 3 years postpartum, respectively.

CONCLUSION

Normal live births were the most common outcome in women exposed to alemtuzumab 12 mg or 24 mg in clinical studies. Spontaneous abortion rate in alemtuzumab-treated patients was comparable with rates in the general population and treatment-naive MS patients, and was not increased in women with pregnancy onset within 4 months of alemtuzumab exposure. There was a minimal increase in postpartum relapses.

CD38: From Positive to Negative Expression after Daratumumab Treatment

CD38 is a glycoprotein expressed at a low level in myeloid and lymphoid tissues. However, it is highly and homogeneously expressed in plasma cells (PC) in multiple myeloma. Daratumumab is a human CD38-specific IgG1 antibody available for the treatment of multiple myeloma in Colombia. It has been authorized in relapsed/refractory disease as front-line treatment for non-eligible stem cell transplantation patients by INVIMA (Instituto Nacional de Vigilancia de Medicamentos y Alimentos) that is the regulatory agency. Daratumumab treatment has been associated with the negativization of the expression of CD38 in PC, demonstrating a resistance mechanism under the clonal evolution theory. We report the case of a 63-year-old male, diagnosed with a relapsed/refractory multiple myeloma, heavily treated, who expressed strong CD38 marker at the beginning of the treatment, with a posterior negativization of CD38 after four cycles of treatment with daratumumab.

A cell-based assay for the detection of neutralizing antibodies against alemtuzumab

Aim:

The humanized anti-CD52 monoclonal antibody alemtuzumab depletes lymphocytes and is currently used to treat relapsing multiple sclerosis. During treatment, anti-alemtuzumab antibodies may develop and reduce effective lymphocyte depletion in future treatment cycles.

Results:

Alemtuzumab–Alexa Fluor 488 conjugate binding to the CHO-CD52 cell surface was inhibited by anti-alemtuzumab antibodies.

Conclusion:

In this proof-of-concept study, a CHO-CD52 cell line has been developed and used to detect the presence of anti-alemtuzumab neutralizing antibodies. This platform provides the basis of an assay for routine screening of serum for neutralizing antibodies from patients treated with alemtuzumab.

We developed a competition assay between alemtuzumab and neutralizing antibodies to adherent CD52-expressing cells. The anti-alemtuzumab antibodies inhibit alemtuzumab–Alexa Fluor 488 binding to cell surface CD52. Reduction in the fluorescence signal is proportional the amount of antidrug antibody in the serum sample.

Therapeutic monoclonal antibodies are currently used for the treatment of numerous diseases and conditions, including relapsing multiple sclerosis, and are the most advanced targeted therapies available. However, they all have the potential to cause immunogenic reactions and generate antibodies that bind to the drug and reduce its therapeutic efficacy. As a result, patients do not receive the expected benefit from treatment, and the effect is cumulative with repeat dosing. The timely detection of antidrug antibodies has the potential to avoid these major risks. Here we describe a cell-based method for detecting anti-alemtuzumab neutralizing antibodies.

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.

Targeting CD52 does not affect murine neuron and microglia function

The humanized anti-CD52 antibody alemtuzumab is successfully used in the treatment of multiple sclerosis (MS) and is thought to exert most of its therapeutic action by depletion and repopulation of mainly B and T lymphocytes. Although neuroprotective effects of alemtuzumab have been suggested, direct effects of anti-CD52 treatment on glial cells and neurons within the CNS itself have not been investigated so far. Here, we show CD52 expression in murine neurons, astrocytes and microglia, both in vitro and in vivo. As expected, anti CD52-treatment caused profound lymphopenia and improved disease symptoms in mice subjected to experimental autoimmune encephalomyelitis (EAE). CD52 blockade also had a significant effect on microglial morphology in organotypic hippocampal slice cultures but did not affect microglial functions. Furthermore, anti-CD52 neither changed baseline neuronal calcium, nor did it act neuroprotective in excitotoxicity models. Altogether, our findings argue against a functionally significant role of CD52 blockade on CNS neurons and microglia. The beneficial effects of alemtuzumab in MS may be exclusively mediated by peripheral immune mechanisms.

Efficacy of alemtuzumab in relapsing-remitting MS patients who received additional courses after the initial two courses: Pooled analysis of the CARE-MS, extension, and TOPAZ studies

Background:

Alemtuzumab is given as two annual courses. Patients with continued disease activity may receive as-needed additional courses.

Objective:

To evaluate efficacy and safety of additional alemtuzumab courses in the CARE-MS (Comparison of Alemtuzumab and Rebif^® Efficacy in Multiple Sclerosis) studies and their extensions.

Methods:

Subgroups were based on the number of additional alemtuzumab courses received. Exclusion criteria: other disease-modifying therapy (DMT); <12-month follow-up after last alemtuzumab course.

Results:

In the additional-courses groups, Courses 3 and 4 reduced annualized relapse rate (12 months before: 0.73 and 0.74, respectively; 12 months after: 0.07 and 0.08). For 36 months after Courses 3 and 4, 89% and 92% of patients were free of 6-month confirmed disability worsening, respectively, with 20% and 26% achieving 6-month confirmed disability improvement. Freedom from magnetic resonance imaging (MRI) disease activity increased after Courses 3 and 4 (12 months before: 43% and 53%, respectively; 12 months after: 73% and 74%). Safety was similar across groups; serious events occurred irrespective of the number of courses.

Conclusion:

Additional alemtuzumab courses significantly improved outcomes, without increased safety risks, in CARE-MS patients with continued disease activity after Course 2. How this compares to outcomes if treatment is switched to another DMT instead remains unknown.

Impact of FcγR variants on the response to alemtuzumab in multiple sclerosis

Allelic variants of genes encoding for the Fc gamma receptors IIIA and IIA have been associated with the clinical response to cell‐depleting antibodies in lymphoma patients. Here, we tested the hypothesis that FCGR3A and FCGR2A high‐affinity polymorphisms predict clinical outcomes to alemtuzumab therapy in 85 patients with relapsing‐remitting multiple sclerosis. No differences in clinical and MRI‐based efficacy parameters, the development of severe infusion‐associated reactions and secondary autoimmune diseases during a 2 year follow‐up was observed based on FCGR3A or FCGR2A polymorphisms. This study does not support the use of FCGR genetic variants to predict clinical outcomes to alemtuzumab.

Context Drives Diversification of Monocytes and Neutrophils in Orchestrating the Tumor Microenvironment

Recent preclinical/clinical studies have underscored the significant impact of tumor microenvironment (TME) on tumor progression in diverse scenarios. Highly heterogeneous and complex, the tumor microenvironment is composed of malignant cancer cells and non-malignant cells including endothelial cells, fibroblasts, and diverse immune cells. Since immune compartments play pivotal roles in regulating tumor progression via various mechanisms, understanding of their multifaceted functions is crucial to developing effective cancer therapies. While roles of lymphoid cells in tumors have been systematically studied for a long time, the complex functions of myeloid cells have been relatively underexplored. However, constant findings on tumor-associated myeloid cells are drawing attention, highlighting the primary effects of innate immune cells such as monocytes and neutrophils in disease progression. This review focuses on hitherto identified contextual developments and functions of monocytes and neutrophils with a special interest in solid tumors. Moreover, ongoing clinical applications are discussed at the end of the review.

Immunological Aspects of Approved MS Therapeutics

Multiple sclerosis (MS) is the most common neurological immune-mediated disease leading to disability in young adults. The outcome of the disease is unpredictable, and over time, neurological disabilities accumulate. Interferon beta-1b was the first drug to be approved in the 1990s for relapsing-remitting MS to modulate the course of the disease. Over the past two decades, the treatment landscape has changed tremendously. Currently, more than a dozen drugs representing 1 substances with different mechanisms of action have been approved (interferon beta preparations, glatiramer acetate, fingolimod, siponimod, mitoxantrone, teriflunomide, dimethyl fumarate, cladribine, alemtuzumab, ocrelizumab, and natalizumab). Ocrelizumab was the first medication to be approved for primary progressive MS. The objective of this review is to present the modes of action of these drugs and their effects on the immunopathogenesis of MS. Each agent's clinical development and potential side effects are discussed.

B Cell-based Therapies for Multiple Sclerosis

The traditional view of multiple sclerosis (MS) as a T cell mediated autoimmune disease of the central nervous system (CNS) has evolved into a concept of an immune-mediated disease where complex bi-directional interactions between T cells, B cells and myeloid cells underlie and shape CNS-directed autoimmunity. B cells are now recognized as major contributors to the pathogenesis of MS, largely due to increased understanding of their biology and the profound anti-inflammatory effects demonstrated by B cell depletion in MS. In this chapter we discuss the fundamental roles B cells play in the pathogenesis of MS and review current and future therapeutic strategies targeting B cells in MS, including B cell depletion with various monoclonal antibodies (mAbs) against the B cell surface markers CD20 and CD19, anti-B cell cytokine therapies, blocking Bruton's tyrosine kinase (BTK) in B cells, and various immunomodulatory and immunosuppressive effects exerted on B cells by virtually all other approved therapies for MS.

Novel Immunotherapies for T Cell Lymphoma and Leukemia

PURPOSE OF REVIEW

Novel immunotherapies such as checkpoint inhibitors, bispecific antibodies, and chimeric antigen receptor T cells are leading to promising responses when treating solid tumors and hematological malignancies. T cell neoplasms include leukemia and lymphomas that are derived from T cells and overall are characterized by poor clinical outcomes. This review describes the rational and preliminary results of immunotherapy for patients with T cell lymphoma and leukemia.

RECENT FINDINGS

For T cell neoplasms, despite significant research effort, only few agents, such as monoclonal antibodies and allogeneic stem cell transplantation, showed some clinical activity. One of the major hurdles to targeting T cell neoplasms is that activation or elimination of T cells, either normal or neoplastic, can cause significant toxicity. A need to develop novel safe and effective immunotherapies for T cell neoplasms exists. In this review, we will discuss the rationale for immunotherapy of T cell leukemia and lymphoma and present the most recent therapeutic approaches.

Alemtuzumab in Multiple Sclerosis: Short- and Long-Term Effects of Immunodepletion on the Peripheral Treg Compartment

Treatment with alemtuzumab is followed by an early increase in Treg frequencies. Whether naïve and memory subsets are differentially affected and how depletion influences dysfunctional MS-Treg is unclear. In this study, we analyzed the effect of alemtuzumab on regulatory T-cells (Treg) in patients with multiple sclerosis (MS). For this purpose 182 blood samples from 25 MS patients were taken shortly before treatment and serially for up to 24 months after two alemtuzumab cycles. We studied Treg by flow cytometry (quantitation, phenotypical characterization), real-time polymerase chain reaction (T-cell receptor (TCR) excision circles [TREC] content), CDR3-spectratyping (clonal distribution), and proliferation assays (suppressive function). CD52-mediated cytolysis of Treg and conventional T-cells was determined by a complement-dependent cytolysis assay. Our studies revealed that 1 week post-alemtuzumab, Treg were depicted at constant frequencies among CD4⁺ T-cells. In contrast, Treg frequencies were massively increased at month 1. Post-depletional Treg exhibited a CD45RO⁺ memory phenotype, a skewed TCR repertoire, and contained minimum TREC numbers. Naïve Treg, thymic markers, and TCR-variability commenced to rise after 6 months but did not attain baseline levels. In vitro, Treg exhibited higher susceptibility to lysis than Tcon. Treg suppressive function constantly increased within 1 year when co-cultured with syngeneic T-cells, but remained stable against allogeneic T-cells from normal donors. Our findings suggest that (1) Treg are not spared from alemtuzumab-mediated depletion and thymopoiesis does not considerably contribute to long-term recovery, (2) either homeostatic proliferation and/or conversion from residual Tcon contributes to Treg expansion during the early post-treatment phase (3) the enhanced inhibitory effect of Treg following alemtuzumab is due to altered composition and reactivity of post-depletional Tcon.

Alemtuzumab Associated Listeria Monocytogenes Meningitis

Purpose Describe a case of Listeria monocytogenes meningitis following initiation of alemtuzumab therapy in a patient diagnosed with relapsing–remitting multiple sclerosis (RRMS). Summary A 44-year-old female presented with headache and fever seven days after completion of an initial course of alemtuzumab for the treatment of RRMS. Blood cultures were positive for gram-positive bacilli. A lumbar puncture revealed cell counts, consistent with bacterial meningitis and magnetic resonance imaging (MRI) revealed abnormal signal enhancement of the left cingulate gyrus. Vancomycin, ceftriaxone, and ampicillin were initiated empirically. Both blood and cerebrospinal fluid cultures resulted positive for Listeria monocytogenes. Antibiotics were narrowed to ampicillin for a treatment duration of 21 days, after which symptoms resolved and she was transitioned home. Alemtuzumab is a CD52-directed cytolytic monoclonal antibody that has previously been implicated in association with cases of Listeria monocytogenes meningitis in other countries. Based on its mechanism of action, previous association, and positive temporal relationship, we hypothesize that alemtuzumab played a substantial role in the development of L. monocytogenes meningitis in this patient. Conclusion To our knowledge, this is the first reported case of alemtuzumab associated Listeria meningitis in the United States. This case highlights the severe lymphopenia associated with alemtuzumab therapy and risk of subsequent opportunistic infection. Heightened vigilance in counseling and monitoring of dietary restrictions is critical both prior to and during alemtuzumab therapy. A greater role of prophylactic antibiotics may also be warranted.

Advances in preventing adverse events during monoclonal antibody management of multiple sclerosis

INTRODUCTION

Decades of pharmacological research in Multiple Sclerosis (MS) led to the development of therapeutic Monoclonal Antibodies (MAbs) with many different mechanisms of action (MoA), potentially able to improve disability outcome but also determining a more complex management of patients. Areas covered: When clinicians select MS treatments, they should consider adverse events (AEs) on individual basis to minimize patients' risks. Some AEs are common and can be easily handled, but rare complications should also be taken into account. The aim of this review is to summarize existing evidence and provide practical recommendations for the management of therapeutic MAbs in MS. Expert opinion: The introduction of MAbs revolutionized MS treatment with an improvement in effectiveness. Unfortunately, this has been coupled with a more complex array of AEs needing a tighter surveillance strategy. A close interaction between general practitioners, neurologists, and other specialists is the key for a safer use of such effective drugs.

Keratinocyte growth factor impairs human thymic recovery from lymphopenia

BACKGROUND

The lymphocyte-depleting antibody alemtuzumab is a highly effective treatment of relapsing-remitting multiple sclerosis (RRMS); however 50% of patients develop novel autoimmunity post-treatment. Most at risk are individuals who reconstitute their T-cell pool by proliferating residual cells, rather than producing new T-cells in the thymus; raising the possibility that autoimmunity might be prevented by increasing thymopoiesis. Keratinocyte growth factor (palifermin) promotes thymopoiesis in non-human primates.

METHODS

Following a dose-tolerability sub-study, individuals with RRMS (duration ≤10 years; expanded disability status scale ≤5·0; with ≥2 relapses in the previous 2 years) were randomised to placebo or 180mcg/kg/day palifermin, given for 3 days immediately prior to and after each cycle of alemtuzumab, with repeat doses at M1 and M3. The interim primary endpoint was naïve CD4+ T-cell count at M6. Exploratory endpoints included: number of recent thymic-emigrants (RTEs) and signal-joint T-cell receptor excision circles (sjTRECs)/mL of blood. The trial primary endpoint was incidence of autoimmunity at M30.

FINDINGS

At M6, individuals receiving palifermin had fewer naïve CD4+T-cells (2.229x107/L vs. 7.733x107/L; p=0.007), RTEs (16% vs. 34%) and sjTRECs/mL (1100 vs. 3396), leading to protocol-defined termination of recruitment. No difference was observed in the rate of autoimmunity between the two groupsConclusion: In contrast to animal studies, palifermin reduced thymopoiesis in our patients. These results offer a note of caution to those using palifermin to promote thymopoiesis in other settings, particularly in the oncology/haematology setting where alemtuzumab is often used as part of the conditioning regime.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01712945Funding: MRC and Moulton Charitable Foundation.

Incidence, management, and outcomes of autoimmune nephropathies following alemtuzumab treatment in patients with multiple sclerosis

Background:

Autoimmune disorders including nephropathies have been reported more frequently in alemtuzumab-treated multiple sclerosis (MS) patients than in the general population.

Objective:

Describe instances of autoimmune nephropathy in alemtuzumab-treated MS patients.

Methods:

Cases were identified from safety monitoring within the alemtuzumab relapsing-remitting multiple sclerosis (RRMS) clinical development program (CDP) or post-marketing, or following off-label use.

Results:

As of 16 June 2017, 16 autoimmune nephropathies have occurred following alemtuzumab treatment for MS. The incidence of autoimmune nephropathies was 0.34% within the CDP (5/1485 patients). The five CDP cases (one of anti-glomerular basement membrane (anti-GBM) disease, two of membranous glomerulonephropathy, and two of serum anti-GBM antibody without typical anti-GBM disease) were identified early, responded to conventional therapy (where needed), and had favorable outcomes. Three of 11 cases outside the CDP occurred following off-label alemtuzumab use prior to approval for RRMS and were all anti-GBM disease. Diagnosis was delayed in one of these three cases and another did not receive appropriate treatment; all three cases resulted in end-stage renal failure. All anti-GBM disease cases with documented urinalysis demonstrated prior microscopic hematuria.

Conclusion:

Close monitoring of alemtuzumab-treated MS patients facilitates diagnosis and treatment early in the nephropathy course when preservation of renal function is more likely.

Pulsed immune reconstitution therapy in multiple sclerosis

Whereas drugs used for maintenance/escalation therapy do not maintain their beneficial effect after cessation of therapy, some new highly effective therapies can show prolonged treatment effects after a short treatment course. Such therapies have been named pulsed immune reconstitution therapies or pulsed immunosuppressive therapies, and typical representatives are alemtuzumab and cladribine. Autologous haematopoietic stem cell transplantation could be considered as the strongest immune reconstitution therapy. Both alemtuzumab and cladribine induce depletion of lymphocytes, and a common mechanism of action is preferential depletion of class-switched and unswitched memory B-cells. Whereas CD-19+ B-lymphocytes repopulate within 6 months, CD4+ T-cells repopulate at a slower rate, taking 1–2 years to reach the lower level of normal. In general, the depletion of lymphocytes is more profound and the repletion of T-cells is slower after alemtuzumab than after cladribine treatment. Both drugs have a strong effect on relapses and magnetic resonance imaging (MRI) activity, and reduce disability worsening. The therapeutic effect is maintained beyond the period of active treatment in a large proportion of patients, which is best documented for alemtuzumab. Adverse effects include reactivation of latent infections such as tuberculosis and risk of herpes zoster. The main disadvantage in alemtuzumab-treated patients is the risk of secondary immune-mediated disorders. Pulsed immune reconstitution therapy is an option as initial therapy in relapsing-remitting multiple sclerosis patients with high disease activity and in patients on treatment with another disease-modifying therapy with significant relapse and/or MRI activity.

Modulating acute neuroinflammation in intracerebral hemorrhage: the potential promise of currently approved medications for multiple sclerosis

The secondary inflammatory injury following intracerebral hemorrhage (ICH) results in increased morbidity and mortality. White blood cells have been implicated as critical mediators of this inflammatory injury. Currently, no medications have been clinically proven to ameliorate or beneficially modulate inflammation, or to improve outcomes by any mechanism, following ICH. However, other neuroinflammatory conditions, such as multiple sclerosis, have approved pharmacologic therapies that modulate the inflammatory response and minimize the damage caused by inflammatory cells. Thus, there is substantial interest in existing therapies for neuroinflammation and their potential applicability to other acute neurological diseases such as ICH. In this review, we examined the mechanism of action of twelve currently approved medications for multiple sclerosis: alemtuzumab, daclizumab, dimethyl fumarate, fingolimod, glatiramer acetate, interferon beta-1a, interferon beta-1b, mitoxantrone, natalizumab, ocrelizumab, rituximab, teriflunomide. We analyzed the existing literature pertaining to the effects of these medications on various leukocytes and also with emphasis on mechanisms of action during the acute period following initiation of therapy. As a result, we provide a valuable summary of the current body of knowledge regarding these therapies and evidence that supports or refutes their likely promise for treating neuroinflammation following ICH.

Brief Report: CD52 Expression on CD4+ T Cells in HIV-Positive Individuals on cART

BACKGROUND

HIV persists in a latent state in quiescent CD4 T cells preventing eradication of HIV. CD52 is a surface molecule modulated by HIV. We aimed at examining factors related to CD52 expression on CD4 T cells in HIV-positive individuals and the impact of initiation of combination antiretroviral therapy (cART).

METHODS

Peripheral blood mononuclear cells from 18 HIV-positive individuals and 10 uninfected age- and sex-matched controls were examined by flow cytometry for CD38 and CD52 expression on CD4 T cells. Stimulation assays were performed on 8 healthy blood donors to determine a cutoff for CD52 expression.

RESULTS

All examined CD4 T cells expressed CD52. However, both CD4 T cells with higher (CD52) and with lower CD52 expression (CD52dim) were found in HIV-positive individuals compared to uninfected controls. Two % CD52dim cells defined groups of high and low CD52: the group of individuals with high CD52 had higher CD4 counts at baseline (447 vs. 54 cells/µL, P = 0.02) and higher increase in CD4 counts during follow-up compared with low CD52 (P = 0.02). After 12 months of cART, CD52 increased (median fluorescence intensity 4846 vs. 5621, P < 0.05), whereas CD38 decreased (median fluorescence intensity 1519 vs. 730, P < 0.0001).

CONCLUSIONS

All HIV-positive individuals in this cohort had CD4 T cells that expressed CD52. Higher CD4 counts were found in those with high CD52. Furthermore, an increase in CD52 was found after 12 months of cART, indicating that anti-CD52 antibodies may be more efficient for depletion of CD4 T cells in HIV-positive individuals on cART.

The role of B cells in multiple sclerosis: Current and future therapies

While it was long held that T cells were the primary mediators of multiple sclerosis (MS) pathogenesis, the beneficial effects observed in response to treatment with Rituximab (RTX), a monoclonal antibody (mAb) targeting CD20, shed light on a key contributor to MS that had been previously underappreciated: B cells. This has been reaffirmed by results from clinical trials testing the efficacy of subsequently developed B cell-depleting mAbs targeting CD20 as well as studies revisiting the effects of previous disease-modifying therapies (DMTs) on B cell subsets thought to modulate disease severity. In this review, we summarize current knowledge regarding the complex roles of B cells in MS pathogenesis and current and potential future B cell-directed therapies.

Infection risk with alemtuzumab decreases over time: pooled analysis of 6-year data from the CAMMS223, CARE-MS I, and CARE-MS II studies and the CAMMS03409 extension study

Background:

Reduced MS disease activity with alemtuzumab versus subcutaneous interferon beta-1a (SC IFNB-1a) in core phase 2/3 studies was accompanied by increased incidence of infections that were mainly nonserious and responsive to treatment. Alemtuzumab efficacy was durable over 6 years.

Objective:

To evaluate infections over 6 years in alemtuzumab-treated patients.

Methods:

Three randomized trials (CAMMS223, Comparison of Alemtuzumab and Rebif Efficacy in Multiple Sclerosis (CARE-MS) I, and CARE-MS II) compared two courses of alemtuzumab 12 mg with SC IFNB-1a 44 μg in patients with active relapsing-remitting MS. An extension study (CAMMS03409) provided further evaluation and as-needed alemtuzumab retreatment.

Results:

Infections occurred more frequently with alemtuzumab 12 mg than SC IFNB-1a during Years 1 (58.7% vs 41.3%) and 2 (52.6% vs 37.7%), but declined for alemtuzumab-treated patients in Years 3 (46.6%), 4 (42.8%), 5 (40.9%), and 6 (38.1%). Serious infections were uncommon (1.0%–1.9% per year). Infections were predominantly (>95%) mild to moderate and included upper respiratory tract infections, urinary tract infections, and mucocutaneous herpetic infections. Prophylactic acyclovir reduced herpetic infections. Lymphocyte counts after alemtuzumab therapy did not predict infection risk.

Conclusion:

Infections with alemtuzumab were mostly mild to moderate and decreased over time, consistent with preservation of components of protective immunity.

Anti-CD52 antibody treatment depletes B cell aggregates in the central nervous system in a mouse model of multiple sclerosis

Background

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) for which several new treatment options were recently introduced. Among them is the monoclonal anti-CD52 antibody alemtuzumab that depletes mainly B cells and T cells in the immune periphery. Considering the ongoing controversy about the involvement of B cells and in particular the formation of B cell aggregates in the brains of progressive MS patients, an in-depth understanding of the effects of anti-CD52 antibody treatment on the B cell compartment in the CNS itself is desirable.

Methods

We used myelin basic protein (MBP)-proteolipid protein (PLP)-induced experimental autoimmune encephalomyelitis (EAE) in C57BL/6 (B6) mice as B cell-dependent model of MS. Mice were treated intraperitoneally either at the peak of EAE or at 60 days after onset with 200 μg murine anti-CD52 vs. IgG2a isotype control antibody for five consecutive days. Disease was subsequently monitored for 10 days. The antigen-specific B cell/antibody response was measured by ELISPOT and ELISA. Effects on CNS infiltration and B cell aggregation were determined by immunohistochemistry. Neurodegeneration was evaluated by Luxol Fast Blue, SMI-32, and Olig2/APC staining as well as by electron microscopy and phosphorylated heavy neurofilament serum ELISA.

Results

Treatment with anti-CD52 antibody attenuated EAE only when administered at the peak of disease. While there was no effect on the production of MP4-specific IgG, the treatment almost completely depleted CNS infiltrates and B cell aggregates even when given as late as 60 days after onset. On the ultrastructural level, we observed significantly less axonal damage in the spinal cord and cerebellum in chronic EAE after anti-CD52 treatment.

Conclusion

Anti-CD52 treatment abrogated B cell infiltration and disrupted existing B cell aggregates in the CNS.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1263-9) contains supplementary material, which is available to authorized users.

Assessment of CD52 expression in "double-hit" and "double-expressor" lymphomas: Implications for clinical trial eligibility

"Double-hit" and "double-expressor" lymphomas represent distinct but overlapping subsets of aggressive B-cell non-Hodgkin lymphoma. The high rates of bone marrow involvement by these lymphomas pose a major therapeutic challenge due to the chemotherapy-resistant nature of the bone marrow microenvironment and the limited utility of rituximab-based salvage regimens in patients with relapsed/refractory disease. Preclinical studies utilizing high-dose cyclophosphamide in combination with the anti-CD52 monoclonal antibody alemtuzumab have recently shown promise in the treatment of intramedullary disease, and a Phase I human trial is now underway. In support of such efforts, here we perform CD52 target validation on a series of double-hit (n = 40) and double-expressor (n = 58) lymphomas using immunohistochemistry. CD52 expression levels varied considerably across samples, however positive staining was observed in 75% of both double-hit and double-expressor lymphomas. Similarly, high levels of CD52 expression were seen in patients whose disease was associated with high-risk clinical features, including primary refractory status (73%), higher IPI score (76%), and bone marrow involvement (74%). CD52 expression was not significantly correlated with diagnostically relevant pathologic features such as morphology, cytogenetic findings or other immunophenotypic features, but was notably present in all cases lacking CD20 expression (n = 6). We propose that CD52 expression status be evaluated on a case-by-case basis to guide eligibility for clinical trial enrollment.

HIV vaccine candidate activation of hypoxia and the inflammasome in CD14+ monocytes is associated with a decreased risk of SIVmac251 acquisition

Qualitative differences in the innate and adaptive responses elicited by different HIV vaccine candidates have not been thoroughly investigated. We tested the ability of the Aventis Pasteur live recombinant canarypox vector (ALVAC)-SIV, DNA-SIV and Ad26-SIV vaccine prime modalities together with two ALVAC-SIV + gp120 protein boosts to reduce the risk of SIVmac251 acquisition in rhesus macaques. We found that the DNA and ALVAC prime regimens were effective, but the Ad26 prime was not. The activation of hypoxia and the inflammasome in CD14+CD16- monocytes, gut-homing CCR5-negative CD4+ T helper 2 (TH2) cells and antibodies to variable region 2 correlated with a decreased risk of SIVmac251 acquisition. By contrast, signal transducer and activator of transcription 3 activation in CD16+ monocytes was associated with an increased risk of virus acquisition. The Ad26 prime regimen induced the accumulation of CX3CR1+CD163+ macrophages in lymph nodes and of long-lasting CD4+ TH17 cells in the gut and lungs. Our data indicate that the selective engagement of monocyte subsets following a vaccine prime influences long-term immunity, uncovering an unexpected association of CD14+ innate monocytes with a reduced risk of SIVmac251 acquisition.

Principles of alemtuzumab immunoablation in hematopoietic cell transplantation for non-malignant diseases in children: A review

Alemtuzumab is a humanized mAb targeted to CD52. Alemtuzumab is highly immunosuppressive with the ability to deplete T and B cells (in addition to other immune cell lines). A growing understanding of the PKs, dosing, and timing of administration of alemtuzumab has allowed for the study of its use as a conditioning agent for allogeneic HCT. The highly immunosuppressive properties of the drug are particularly appealing in the setting of non-malignant HCT, where GVHD provides no clinical benefit and relapse of malignancy is not applicable. In addition, the degree of immune suppression achieved with alemtuzumab has allowed for a reduction in the intensity of myeloablative cytotoxic agents included in some HCT conditioning regimens, allowing for fewer acute and late toxicities. This review paper will provide a comprehensive summary of the mechanism of action, PKs, dosing, and timing of alemtuzumab, a brief description of its use in various allogeneic HCT protocols for non-malignant conditions and a summary of the data regarding its use for GVHD therapy. The goal of this review was to provide an understanding as to how alemtuzumab might be safely incorporated into HCT conditioning regimens for children with non-malignant disease, allowing for expanded access to curative HCT therapy.

The therapeutic effect of anti-CD52 treatment in murine experimental autoimmune encephalomyelitis is associated with altered IL-33 and ST2 expression levels

Experimental autoimmune encephalomyelitis (EAE) mice were administered with murine anti-CD52 antibody to investigate its therapeutic effect and whether the treatment modulates IL-33 and ST2 expression. EAE severity and central nervous system (CNS) inflammation were reduced following the treatment, which was accompanied by peripheral T and B lymphocyte depletion and reduced production of various cytokines including IL-33, while sST2 was increased. In spinal cords of EAE mice, while the number of IL-33⁺ cells remained unchanged, the extracellular level of IL-33 protein was significantly reduced in anti-CD52 antibody treated mice compared with controls. Furthermore the number of ST2⁺ cells in the spinal cord of treated EAE mice was downregulated due to decreased inflammation and immune cell infiltration in the CNS. These results suggest that treatment with anti-CD52 antibody differentially alters expression of IL-33 and ST2, both systemically and within the CNS, which may indicate IL-33/ST2 axis is involved in the action of the antibody in inhibiting EAE.

Reduced Expression of Membrane Complement Regulatory Protein CD59 on Leukocytes following Lung Transplantation

Cellular protection against undesired effects of complement activation is provided by expression of membrane-bound complement regulatory proteins including CD59. This protein prevents membrane attack complex formation and is considered to be involved in graft accommodation. Also, CD59 downregulates CD4+ and CD8+ T-cell activation and proliferation. It is unknown whether CD59 expression is affected by transplantation. The aim of this study was to evaluate the quantitative CD59 antigen expression on distinct leukocyte subsets following lung transplantation (n = 26) and to investigate whether this differs from pretransplantation (n = 9). The results show that CD59 expression on leukocytes is significantly lower posttransplantation compared with healthy controls (p = 0.002) and pretransplantation (p < 0.0001). Moreover, the CD59 expression diminishes posttransplantation on all distinct lymphocyte subsets (p < 0.02). This effect appeared to be specific for CD59 since the expression of other surface markers remained stable or inclined following transplantation. The highest antigen expression posttransplantation was observed on CD4+ T cells and monocytes (p ≤ 0.002). These findings show that CD59 expression on leukocytes diminishes posttransplantation, which could result in decreased resistance against complement and enhanced T-cell activation. If such reduction in CD59 expression also occurs on endothelial cells from the transplanted organ, this could lead to a change into a prothrombotic and proinflammatory phenotype.

CD52 inhibits Toll-like receptor activation of NF-κB and triggers apoptosis to suppress inflammation

Soluble CD52 is a small glycoprotein that suppresses T-cell activation, but its effect on innate immune cell function is unknown. Here we demonstrate that soluble CD52 inhibits Toll-like receptor and tumor necrosis factor receptor signaling to limit activation of NF-κB and thereby suppress the production of inflammatory cytokines by macrophages, monocytes and dendritic cells. At higher concentrations, soluble CD52 depletes the short-lived pro-survival protein MCL-1, contributing to activation of the BH3-only proteins BAX and BAK to cause intrinsic apoptotic cell death. In vivo, administration of soluble CD52 suppresses lipopolysaccharide (LPS)-induced cytokine secretion and other features of endotoxic shock, whereas genetic deletion of CD52 exacerbates LPS responses. Thus, soluble CD52 exhibits broad immune suppressive effects that signify its potential as an immunotherapeutic agent.

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.

Alemtuzumab CARE-MS I 5-year follow-up: Durable efficacy in the absence of continuous MS therapy

Objective:

To evaluate 5-year efficacy and safety of alemtuzumab in treatment-naive patients with active relapsing-remitting MS (RRMS) (CARE-MS I; NCT00530348).

Methods:

Alemtuzumab-treated patients received treatment courses at baseline and 12 months later; after the core study, they could enter an extension (NCT00930553) with as-needed alemtuzumab retreatment for relapse or MRI activity. Assessments included annualized relapse rate (ARR), 6-month confirmed disability worsening (CDW; ≥1-point Expanded Disability Status Scale [EDSS] score increase [≥1.5 if baseline EDSS = 0]), 6-month confirmed disability improvement (CDI; ≥1-point EDSS decrease [baseline score ≥2.0]), no evidence of disease activity (NEDA), brain volume loss (BVL), and adverse events (AEs).

Results:

Most alemtuzumab-treated patients (95.1%) completing CARE-MS I enrolled in the extension; 68.5% received no additional alemtuzumab treatment. ARR remained low in years 3, 4, and 5 (0.19, 0.14, and 0.15). Over years 0–5, 79.7% were free of 6-month CDW; 33.4% achieved 6-month CDI. Most patients (61.7%, 60.2%, and 62.4%) had NEDA in years 3, 4, and 5. Median yearly BVL improved over years 2–4, remaining low in year 5 (years 1–5: −0.59%, −0.25%, −0.19%, −0.15%, and −0.20%). Exposure-adjusted incidence rates of most AEs declined in the extension relative to the core study. Thyroid disorder incidences peaked at year 3 and subsequently declined.

Conclusions:

Based on these data, alemtuzumab provides durable efficacy through 5 years in the absence of continuous treatment, with most patients not receiving additional courses.

ClinicalTrials.gov identifier:

NCT00530348; NCT00930553.

Classification of evidence:

This study provides Class III evidence that alemtuzumab durably improves efficacy outcomes and slows BVL in patients with RRMS.

Alemtuzumab for Multiple Sclerosis

Alemtuzumab is a humanised anti-CD52 monoclonal antibody approved for use in active, relapsing multiple sclerosis (MS). Administration results in a rapid depletion of circulating lymphocytes with a subsequent beneficial immune reconstitution. Early open-label experience and recent clinical trials have demonstrated a dramatic effect on relapse rates as well as a positive effect on radiological disease outcomes and disability measures. Despite a mechanism of action that results in profound lymphopaenia, opportunistic infections are rarely seen and no excess association with malignancy has been identified. However, acquired autoimmune disease (AID) is a common adverse event following treatment, necessitating rigorous monitoring in order to facilitate prompt detection and management. Despite this issue, a unique dosing schedule and durability of effect make alemtuzumab a welcome addition to currently available treatment options for MS.

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.

Treatment advances and prognosis for patients with adult T-cell leukemia-lymphoma

A classification for adult T-cell leukemia-lymphoma (ATL) based on clinical features was proposed in 1991: acute, lymphoma, chronic, and smoldering types, and their median survival times (MSTs) were reported to be 6.2, 10.2, 24.3 months, and not reached, respectively. Several new therapies for ATL have since been developed, i.e. dose-intensity multi-agent chemotherapies, allogeneic hematopoietic stem cell transplantation (allo-HSCT), monoclonal antibodies, and anti-viral therapy. The monoclonal antibody to CCR4, mogamulizumab, clearly improved response rates in patients with treatment-naïve and relapsed aggressive ATL, and has the potential to provide a survival advantage. The outcomes of allo-HSCT have been reported since the early 2000s. High treatment-related mortality was initially the crucial issue associated with this treatment approach; however, reduced intensity conditioning regimens have decreased the risk of treatment-related mortality. The introduction of allo- HSCT has had a positive impact on the prognosis of and potential curability with treatments for ATL. A meta-analysis of a treatment with interferon-α and zidovudine (IFN/AZT) revealed a survival benefit in patients with the leukemic subtype. A phase 3 study comparing IFN/AZT with watchful waiting in patients with indolent ATL is ongoing in Japan. Several clinical trials on novel agents are currently being conducted, such as the histone deacetylase inhibitors, alemtuzumab, brentuximab vedotin, nivolumab, and an EZH1/2 dual inhibitor.

Monoclonal Antibodies for Relapsing Multiple Sclerosis: A Review of Recently Marketed and Late-Stage Agents

Treatment of multiple sclerosis (MS) has improved considerably over the last decade because of new insights into MS pathology and biotechnological advances. This has led to the development of new potent pharmaceutical compounds targeting different processes in the complex autoimmune pathology leading to chronic central nervous system (CNS) demyelination, neural loss, and, finally, neurological disability. Although a number of disease-modifying treatments are available for the treatment of the inflammatory phase of MS, there is still a need for highly efficacious therapies with an acceptable safety profile in order to gain therapeutic control early in the disease course. Monoclonal antibodies have proven to be some of the most efficacious disease-modifying therapies in the field of MS, and recent developments in clinical research hold promise for new compounds fulfilling the need for improved safety and high efficacy. We review recent developments in the field of therapeutic monoclonal antibodies used for the treatment of MS and current information on the mode of action, efficacy, and safety of existing and emerging therapeutic monoclonal antibodies as well as their place within the context of different treatment strategies. Finally, we consider the most important future developments.

The immunological function of CD52 and its targeting in organ transplantation

INTRODUCTION

CD52 (Campath-1 antigen), a glycoprotein of 12 amino acids anchored to glycosylphosphatidylinositol, is widely expressed on the cell surface of immune cells, such as mature lymphocytes, natural killer cells (NK), eosinophils, neutrophils, monocytes/macrophages, and dendritic cells (DCs). The anti-CD52 mAb, alemtuzumab, was used widely in clinics for the treatment of patients such as organ transplantation. In the present manuscript, we will briefly summarize the immunological function of CD52 and discuss the application of anti-CD52 mAb in transplantation settings.

FINDINGS

We reviewed studies published until July 2016 to explore the role of CD52 in immune cell function and its implication in organ transplantation. We showed that ligation of cell surface CD52 molecules may offer costimulatory signals for T-cell activation and proliferation. However, soluble CD52 molecules will interact with the inhibitory sialic acid-binding immunoglobulin-like lectin 10 (Siglec10) to significantly inhibit T cell proliferation and activation. Although the physiological and pathological significances of CD52 molecules are still poorly understood, the anti-CD52 mAb, alemtuzumab, was used widely for the treatment of patients with chronic lymphocytic leukemia, autoimmune diseases as well as cell and organ transplantation in clinics.

CONCLUSION

Studies clearly showed that CD52 can modulate T-cell activation either by its intracellular signal pathways or by the interaction of soluble CD52 and Siglec-10 expressing on T cells. However, the regulatory functions of CD52 on other immune cell subpopulations in organ transplantation require to be studied in the near future.

Mechanism of action of three newly registered drugs for multiple sclerosis treatment

Multiple sclerosis (MS) is a disease of suspected autoimmune origin leading to neurodegeneration. The disease pathomechanism is considered to be primarily based on neuroinflammation directed against myelin antigens caused by autoreactive T cells. MS etiology remains still unknown, which makes it difficult to create an efficient therapy, therefore, MS treatment targets mechanisms involved in disease pathology. In this review, we present the mechanism of action of three newly registered drugs for MS. Dimethyl fumarate (DMF) is an agent presenting a broad spectrum of action. Its main activity is based on activating the nuclear factor E2 dependent pathway leading to antioxidant enzyme synthesis. DMF in general suppresses the pro-inflammatory immune activity and exerts a neuroprotective action. Teriflunomide is a more focused drug, acting as an inhibitor of pyrimidines synthesis, important for rapidly dividing cells such as activated lymphocytes. Similarly, alemtuzumab, an anti-CD52 antibody, causes depletion of mainly lymphocytes. Since in MS pathology, T and B cells are involved, this mode of action is promising.

Targeting the Monocyte-Macrophage Lineage in Solid Organ Transplantation

There is an unmet clinical need for immunotherapeutic strategies that specifically target the active immune cells participating in the process of rejection after solid organ transplantation. The monocyte–macrophage cell lineage is increasingly recognized as a major player in acute and chronic allograft immunopathology. The dominant presence of cells of this lineage in rejecting allograft tissue is associated with worse graft function and survival. Monocytes and macrophages contribute to alloimmunity via diverse pathways: antigen processing and presentation, costimulation, pro-inflammatory cytokine production, and tissue repair. Cross talk with other recipient immune competent cells and donor endothelial cells leads to amplification of inflammation and a cytolytic response in the graft. Surprisingly, little is known about therapeutic manipulation of the function of cells of the monocyte–macrophage lineage in transplantation by immunosuppressive agents. Although not primarily designed to target monocyte–macrophage lineage cells, multiple categories of currently prescribed immunosuppressive drugs, such as mycophenolate mofetil, mammalian target of rapamycin inhibitors, and calcineurin inhibitors, do have limited inhibitory effects. These effects include diminishing the degree of cytokine production, thereby blocking costimulation and inhibiting the migration of monocytes to the site of rejection. Outside the field of transplantation, some clinical studies have shown that the monoclonal antibodies canakinumab, tocilizumab, and infliximab are effective in inhibiting monocyte functions. Indirect effects have also been shown for simvastatin, a lipid lowering drug, and bromodomain and extra-terminal motif inhibitors that reduce the cytokine production by monocytes–macrophages in patients with diabetes mellitus and rheumatoid arthritis. To date, detailed knowledge concerning the origin, the developmental requirements, and functions of diverse specialized monocyte–macrophage subsets justifies research for therapeutic manipulation. Here, we will discuss the effects of currently prescribed immunosuppressive drugs on monocyte/macrophage features and the future challenges.

Impact of Desensitization on Antiviral Immunity in HLA-Sensitized Kidney Transplant Recipients

Viral infections represent significant morbidity and mortality factors in kidney transplant recipients, with CMV, EBV, and BKV infections being most common. Desensitization (DES) with IVIg and rituximab with/without plasma exchange followed by kidney transplantation with alemtuzumab induction increased successful transplant rates in HLA-sensitized patients but may represent an increased risk for viral infections due to severe lymphocyte depletion. Here, we report on the posttransplant viral infection status in 372 DES versus 538 non-DES patients. CMV and EBV viremia were significantly lower in DES patients, while BKV viremia was similar. This trend was observed primarily in CMV sero(-), EBV sero(+), and sero(-) patients. No patient developed PTLD. The incidence of BKAN, allograft, and patient survival was similar in both groups. These viral infections were not associated with subsequent allograft rejection which occurred within 6 months after the infection. Conclusions. The IVIg + rituximab desensitization combined with alemtuzumab induction with triple immunosuppression maintenance does not increase the risk for CMV, EBV, and BKV infections. Possible factors include, in addition to posttransplant antiviral prophylaxis and PCR monitoring, presence of memory T cells and antibodies specific to CMV and likely EBV, NK cell-mediated ADCC despite lymphocyte depletion, elimination of EBV and CMV reservoirs by rituximab and alemtuzumab, and use of IVIg with antiviral properties.