Selective targeting of T cell subsets: focus on alefacept - a remittive therapy for psoriasis

Research Advances in Fusion Protein-Based Drugs for Diabetes Treatment

Diabetes mellitus (DM) is a chronic metabolic disease characterized by elevated blood glucose levels, resulting in multi-organ dysfunction and various complications. Fusion proteins can form multifunctional complexes by combining the target proteins with partner proteins. It has significant advantages in improving the performance of the target proteins, extending their biological half-life, and enhancing patient drug compliance. Fusion protein-based drugs have emerged as promising new drugs in diabetes therapeutics. However, there has not been a systematic review of fusion protein-based drugs for diabetes therapeutics. Hence, we conducted a comprehensive review of published literature on diabetic fusion protein-based drugs for diabetes, with a primary focus on immunoglobulin G (IgG) fragment crystallizable (Fc) region, albumin, and transferrin (TF). This review aims to provide a reference for the subsequent development and clinical application of fusion protein-based drugs in diabetes therapeutics.

Comprehensive Analysis to Identify Rh Family C Glycoprotein (RHCG) as the Causative Gene for Psoriasis and Search for Alternative Treatment Modalities

Background

Psoriasis is a complex autoimmune disease. Frequent interactions between epidermal and immune cells are likely to be responsible for the strong heterogeneity of psoriasis. Therefore, our work aims to build on current knowledge and further search for new molecular mechanisms related to psoriasis pathogenesis in order to develop new targeted drugs.

Methods

Data from psoriasis samples were obtained from the Gene Expression Omnibus (GEO) database, and batch effects were corrected using the "Combat" algorithm in the "SVA" package. Functional annotation of differential genes in psoriasis was performed by Gene set enrichment analysis (GSEA). Core functional modules were identified using the Multiscale Embedded Gene Co-Expression Network Analysis (MEGENA) algorithm for selection from the differential gene interaction network. The expression and potential function of Rh Family C Glycoprotein (RHCG) was predicted in single cell data by the "Seurat" package and validated in psoriasis samples by multiplex immunofluorescence. In addition, the regulatory function of HOP Homeobox (HOPX) on RHCG in keratinocytes was confirmed using RNA interference. Using immune infiltration analysis, RHCG and DC cells were analyzed for their association. Finally, the molecular mechanisms of treatment of psoriasis using Tripterygii Radix (TR) and Cinnamomi Ramulus (CR) were explored through network pharmacology and experimental validation.

Results

Immune response (represented by C1_2) and collagen matrix formation (represented by C1_3) were identified as two important pathogenic factors in psoriasis and helped to define new biological subtypes of psoriasis. One important psoriasis hub gene, RHCG, was obtained and found to be closely associated with keratinocyte differentiation as well as DC cell maturation. And RHCG was regulated by HOPX in keratinocytes. In addition, the mechanism of action of CR and TR in the treatment of psoriasis was tentatively confirmed to be related to TRPV3, NFKB2, and YAP1.

Conclusions

Our study identifies a new causal disease gene (RHCG) and offers potential alternatives for the treatment of psoriasis.

New Horizons: Emerging Antidiabetic Medications

Over the past century, since the discovery of insulin, the therapeutic offer for diabetes has grown exponentially, in particular for type 2 diabetes (T2D). However, the drugs in the diabetes pipeline are even more promising because of their impressive antihyperglycemic effects coupled with remarkable weight loss. An ideal medication for T2D should target not only hyperglycemia but also insulin resistance and obesity. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and the new class of GLP1 and gastric inhibitory polypeptide dual RAs counteract 2 of these metabolic defects of T2D, hyperglycemia and obesity, with stunning results that are similar to the effects of metabolic surgery. An important role of antidiabetic medications is to reduce the risk and improve the outcome of cardiovascular diseases, including coronary artery disease and heart failure with reduced or preserved ejection fraction, as well as diabetic nephropathy, as shown by SGLT2 inhibitors. This review summarizes the main drugs currently under development for the treatment of type 1 diabetes and T2D, highlighting their strengths and side effects.

Repurposing approved therapeutics for new indication: Addressing unmet needs in psoriasis treatment

Psoriasis is a chronic inflammatory autoimmune condition manifested by the hyperproliferation of keratinocytes with buildup of inflammatory red patches and scales on skin surfaces. The available treatment options for the management of psoriasis have various drawbacks, and the clinical need for effective therapeutics for this disease remain unmet; therefore, the approaches of drug repurposing or drug repositioning could potentially be used for treating indications of psoriasis. The undiscovered potential of drug repurposing or repositioning compensates for the limitations and hurdles in drug discovery and drug development processes. Drugs initially approved for other indications, including anticancer, antidiabetic, antihypertensive, and anti-arthritic activities, are being investigated for their potential in psoriasis management as a new therapeutic indication by using repurposing strategies. This article envisages the potential of various therapeutics for the management of psoriasis.

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Psoriasis is an autoimmune inflammatory skin disorder with complex physiology.

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Conventional treatments for psoriasis cause severe adverse effects; therefore an unmet need remains for safer and more effective therapies for psoriasis.

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Various drugs that effectively decrease the inflammation and proliferation of skin cells can be repurposed for the management of psoriasis.

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Repurposed drugs provide various incentives to the pharmaceutical industry.

Emerging Pathophysiological Targets of Psoriasis for Future Therapeutic Strategies

Psoriasis is a chronic autoimmune skin disorder which involves complex interactions between genes, keratinocytes, T-cells and inflammatory cells. It affects 2-3% population worldwide. Molecular biology and cellular immunology of psoriasis, when linked with biotechnology and genetic studies can help researchers to understand the pathophysiology of psoriasis. T-cells activation, keratinocyte hyperproliferation, and angiogenesis are the core mechanisms entailed in the development of psoriasis lesion. Investigators are trying to overcome the challenges of complex pathophysiology pathways involved in this disorder. The different possible hypotheses for its pathophysiology such as growth factors, enzymes, inflammation, and genetic factors mediated pathophysiology have been described in the present review paper in detail. Clinically available drugs only control the symptoms of psoriasis but are not effective for the treatment of the disorder completely and are also associated with some side effects such as itching, renal disorders, hematologic, nonmelanoma skin cancer, pulmonary, gastrointestinal toxicity, etc. This paper made an effort to understand the pathophysiological targets, discuss the research done so far and the treatments available for the effective management of psoriasis.

Exhausted-like CD8+ T cell phenotypes linked to C-peptide preservation in alefacept-treated T1D subjects

Clinical trials of biologic therapies in type 1 diabetes (T1D) aim to mitigate autoimmune destruction of pancreatic β cells through immune perturbation and serve as resources to elucidate immunological mechanisms in health and disease. In the T1DAL trial of alefacept (LFA3-Ig) in recent-onset T1D, endogenous insulin production was preserved in 30% of subjects for 2 years after therapy. Given our previous findings linking exhausted-like CD8+ T cells to beneficial response in T1D trials, we applied unbiased analyses to sorted CD8+ T cells to evaluate their potential role in T1DAL. Using RNA sequencing, we found that greater insulin C-peptide preservation was associated with a module of activation- and exhaustion-associated genes. This signature was dissected into 2 CD8 memory phenotypes through correlation with cytometry data. These cells were hypoproliferative, shared expanded rearranged TCR junctions, and expressed exhaustion-associated markers including TIGIT and KLRG1. The 2 phenotypes could be distinguished by reciprocal expression of CD8+ T and NK cell markers (GZMB, CD57, and inhibitory killer cell immunoglobulin-like receptor [iKIR] genes), versus T cell activation and differentiation markers (PD-1 and CD28). These findings support previous evidence linking exhausted-like CD8+ T cells to successful immune interventions for T1D, while suggesting that multiple inhibitory mechanisms can promote this beneficial cell state.

CD4+CD25+CD127hi cell frequency predicts disease progression in type 1 diabetes

Transient partial remission, a period of low insulin requirement experienced by most patients soon after diagnosis, has been associated with mechanisms of immune regulation. A better understanding of such natural mechanisms of immune regulation might identify new targets for immunotherapies that reverse type 1 diabetes (T1D). In this study, using Cox model multivariate analysis, we validated our previous findings that patients with the highest frequency of CD4⁺CD25⁺CD127^hi (127-hi) cells at diagnosis experience the longest partial remission, and we showed that the 127-hi cell population is a mix of Th1- and Th2-type cells, with a significant bias toward antiinflammatory Th2-type cells. In addition, we extended these findings to show that patients with the highest frequency of 127-hi cells at diagnosis were significantly more likely to maintain β cell function. Moreover, in patients treated with alefacept in the T1DAL clinical trial, the probability of responding favorably to the antiinflammatory drug was significantly higher in those with a higher frequency of 127-hi cells at diagnosis than those with a lower 127-hi cell frequency. These data are consistent with the hypothesis that 127-hi cells maintain an antiinflammatory environment that is permissive for partial remission, β cell survival, and response to antiinflammatory immunotherapy.

Costimulation Blockade in Kidney Transplant Recipients

Costimulation between T cells and antigen-presenting cells is essential for the regulation of an effective alloimmune response and is not targeted with the conventional immunosuppressive therapy after kidney transplantation. Costimulation blockade therapy with biologicals allows precise targeting of the immune response but without non-immune adverse events. Multiple costimulation blockade approaches have been developed that inhibit the alloimmune response in kidney transplant recipients with varying degrees of success. Belatacept, an immunosuppressive drug that selectively targets the CD28-CD80/CD86 pathway, is the only costimulation blockade therapy that is currently approved for kidney transplant recipients. In the last decade, belatacept therapy has been shown to be a promising therapy in subgroups of kidney transplant recipients; however, the widespread use of belatacept has been tempered by an increased risk of acute kidney transplant rejection. The purpose of this review is to provide an overview of the costimulation blockade therapies that are currently in use or being developed for kidney transplant indications.

The immunological synapse as a pharmacological target

The development of T cell mediated immunity relies on the assembly of a highly specialized interface between T cell and antigen presenting cell (APC), known as the immunological synapse (IS). IS assembly is triggered when the T cell receptor (TCR) binds to specific peptide antigen presented in association to the major histocompatibility complex (MHC) by the APC, and is followed by the spatiotemporal dynamic redistribution of TCR, integrins, co-stimulatory receptors and signaling molecules, allowing for the fine-tuning and integration of the signals that lead to T cell activation. The knowledge acquired to date about the mechanisms of IS assembly underscores this structure as a robust pharmacological target. The activity of molecules involved in IS assembly and function can be targeted by specific compounds to modulate the immune response in a number of disorders, including cancers and autoimmune diseases, or in transplanted patients. Here, we will review the state-of-the art of the current therapies which exploit the IS to modulate the immune response.

Roles of CD48 in regulating immunity and tolerance

CD48, a member of the signaling lymphocyte activation molecule family, participates in adhesion and activation of immune cells. Although constitutively expressed on most hematopoietic cells, CD48 is upregulated on subsets of activated cells. CD48 can have activating roles on T cells, antigen presenting cells and granulocytes, by binding to CD2 or bacterial FimH, and through cell intrinsic effects. Interactions between CD48 and its high affinity ligand CD244 are more complex, with both stimulatory and inhibitory outcomes. CD244:CD48 interactions regulate target cell lysis by NK cells and CTLs, which are important for viral clearance and regulation of effector/memory T cell generation and survival. Here we review roles of CD48 in infection, tolerance, autoimmunity, and allergy, as well as the tools used to investigate this receptor. We discuss stimulatory and regulatory roles for CD48, its potential as a therapeutic target in human disease, and current challenges to investigation of this immunoregulatory receptor.

Can We Repurpose FDA-Approved Alefacept to Diminish the HIV Reservoir?

Current anti-retroviral treatment (ART) for HIV is effective in maintaining HIV at undetectable levels. However, cessation of ART results in immediate and brisk rebound of viremia to high levels. This rebound is driven by an HIV reservoir mainly enriched in memory CD4+ T cells. In order to provide any form of functional HIV Cure, elimination of this viral reservoir has become the focus of current HIV cure strategies. Alefacept was initially developed for the treatment of chronic plaque psoriasis. Alefacept is a chimeric fusion protein consisting of the CD2-binding portion of human leukocyte function antigen-3 (LFA3) linked to the Fc region of human IgG1 (LFA3-Fc). Alefacept was designed to inhibit memory T cell activation that contributes to the chronic autoimmune disease psoriasis by blocking the CD2 coreceptor. However, it was found to deplete memory T cells that express high levels of CD2 via NK cell-mediated antibody dependent cell cytotoxicity (ADCC) in vivo. Phase II and phase III clinical trials of alefacept with psoriasis patients demonstrated promising results and an excellent safety profile. Subsequently, alefacept has been successfully repurposed for other memory T cell-mediated autoimmune diseases including skin diseases other than psoriasis, organ transplantation and type I diabetes (T1D). Herein, we review our specific strategy to repurpose the FDA approved biologic alefacept to decrease and hopefully someday eliminate the HIV reservoir, for which CD2hi memory CD4+ T cells are a significant contributor.

Targeting memory T cells in type 1 diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease that leads to progressive destruction of pancreatic beta cells. Compared to healthy controls, a characteristic feature of patients with T1D is the presence of self-reactive T cells with a memory phenotype. These autoreactive memory T cells in both the CD4(+) and CD8(+) compartments are likely to be long-lived, strongly responsive to antigenic stimulation with less dependence on costimulation for activation and clonal expansion, and comparatively resistant to suppression by regulatory T cells (Tregs) or downregulation by immune-modulating agents. Persistence of autoreactive memory T cells likely contributes to the difficulty in preventing disease progression in new-onset T1D and maintaining allogeneic islet transplants by regular immunosuppressive regimens. The majority of immune interventions that have demonstrated some success in preserving beta cell function in the new-onset period have been shown to deplete or modulate memory T cells. Based on these and other considerations, preservation of residual beta cells early after diagnosis or restoration of beta cell mass by use of stem cell or transplantation technology will require a successful strategy to control the autoreactive memory T cell compartment, which could include depletion, inhibition of homeostatic cytokines, induction of hyporesponsiveness, or a combination of these approaches.

Alefacept provides sustained clinical and immunological effects in new-onset type 1 diabetes patients

BACKGROUND

Type 1 diabetes (T1D) results from destruction of pancreatic β cells by autoreactive effector T cells. We hypothesized that the immunomodulatory drug alefacept would result in targeted quantitative and qualitative changes in effector T cells and prolonged preservation of endogenous insulin secretion by the remaining β cells in patients with newly diagnosed T1D.

METHODS

In a multicenter, randomized, double-blind, placebo-controlled trial, we compared alefacept (two 12-week courses of 15 mg/wk i.m., separated by a 12-week pause) with placebo in patients with recent onset of T1D. Endpoints were assessed at 24 months and included meal-stimulated C-peptide AUC, insulin use, hypoglycemic events, and immunologic responses.

RESULTS

A total of 49 patients were enrolled. At 24 months, or 15 months after the last dose of alefacept, both the 4-hour and the 2-hour C-peptide AUCs were significantly greater in the treatment group than in the control group (P = 0.002 and 0.015, respectively). Exogenous insulin requirements were lower (P = 0.002) and rates of major hypoglycemic events were about 50% reduced (P < 0.001) in the alefacept group compared with placebo at 24 months. There was no apparent between-group difference in glycemic control or adverse events. Alefacept treatment depleted CD4+ and CD8+ central memory T cells (Tcm) and effector memory T cells (Tem) (P < 0.01), preserved Tregs, increased the ratios of Treg to Tem and Tcm (P < 0.01), and increased the percentage of PD-1+CD4+ Tem and Tcm (P < 0.01).

CONCLUSIONS

In patients with newly diagnosed T1D, two 12-week courses of alefacept preserved C-peptide secretion, reduced insulin use and hypoglycemic events, and induced favorable immunologic profiles at 24 months, well over 1 year after cessation of therapy.

TRIAL REGISTRATION

https://clinicaltrials.gov/ NCT00965458.

FUNDING

NIH and Astellas.

Biological products for the treatment of psoriasis: therapeutic targets, pharmacodynamics and disease-drug-drug interaction implications

Psoriasis is a chronic inflammatory skin disease condition that involves altered expression of a broad spectrum of proinflammatory cytokines which are associated with activation of T cells and proliferation of keratinocytes. Currently approved biological products for psoriasis treatment fall into two main classes: cytokine modulators and biologics targeting T cells. In psoriatic patients, elevated levels of proinflammatory cytokines are observed. Elevated proinflammatory cytokines can suppress some cytochrome P450 (CYP) enzymes, and the treatment of psoriasis with biological products can reduce proinflammatory cytokine levels. Therefore, the exposure of CYP substrate drugs is anticipated to be affected by the psoriasis disease resulting in a higher exposure than in healthy state (named disease-drug interaction) as well as by the biological treatments due to disease improvements resulting in a decrease in exposure (named disease-drug-drug interaction, disease-DDI). However, the quantitative impact on CYP substrate exposure due to disease or due to treatment with biological products remains to be evaluated. The objective of the current review is to provide an overview of the therapeutic targets and cytokine-related pharmacodynamic effects of biological products in psoriasis treatment with a particular focus on their implications for disease-DDI. The clinical study design considerations for psoriasis disease-DDI evaluation are also discussed.

Diabetes: Immunotherapy for T1DM--still not there yet

Alefacept, a fusion protein approved for psoriasis, has been trialled in patients with new-onset type 1 diabetes mellitus. However, the withdrawal of the drug from the US market and the unmet primary end point do not raise hope for this drug, even though some secondary end points were met and the study highlighted interesting immunological efficacy.

Alefacept promotes immunosuppression-free renal allograft survival in nonhuman primates via depletion of recipient memory T cells

Renal allograft tolerance has been achieved in MHC-mismatched primates via nonmyeloablative conditioning beginning 6 days prior to planned kidney and donor bone marrow transplantation (DBMT). To extend the applicability of this approach to deceased donor transplantation, we recently developed a novel-conditioning regimen, the "delayed protocol" in which donor bone marrow (DBM) is transplanted several months after kidney transplantation. However, activation/expansion of donor-reactive CD8(+) memory T cells (TMEM) occurring during the interval between kidney and DBM transplantation impaired tolerance induction using this strategy. In the current study, we tested whether, Alefacept, a fusion protein which targets LFA-3/CD2 interactions and selectively depletes CD2(high) CD8(+) effector memory T cells (TEM) could similarly induce long-term immunosuppression-free renal allograft survival but avoid the deleterious effects of anti-CD8 mAb treatment. We found that Alefacept significantly delayed the expansion of CD2(high) cells including CD8(+) TEM while sparing naïve CD8(+) T and NK cells and achieved mixed chimerism and long-term immunosuppression-free renal allograft survival. In conclusion, elimination of CD2(high) T cells represents a promising approach to prevent electively the expansion/activation of donor-reactive TEM and promotes tolerance induction via the delayed protocol mixed chimerism approach.

Targeting of memory T cells with alefacept in new-onset type 1 diabetes (T1DAL study): 12 month results of a randomised, double-blind, placebo-controlled phase 2 trial

BACKGROUND

Type 1 diabetes results from autoimmune targeting of the pancreatic β cells, likely mediated by effector memory T (Tem) cells. CD2, a T cell surface protein highly expressed on Tem cells, is targeted by the fusion protein alefacept, depleting Tem cells and central memory T (Tcm) cells. We postulated that alefacept would arrest autoimmunity and preserve residual β cells in patients newly diagnosed with type 1 diabetes.

METHODS

The T1DAL study is a phase 2, double-blind, placebo-controlled trial in patients with type 1 diabetes, aged 12-35 years who, within 100 days of diagnosis, were enrolled at 14 US sites. Patients were randomly assigned (2:1) to receive alefacept (two 12-week courses of 15 mg intramuscularly per week, separated by a 12-week pause) or a placebo. Randomisation was stratified by site, and was computer-generated with permuted blocks of three patients per block. All participants and site personnel were masked to treatment assignment. The primary endpoint was the change from baseline in mean 2 h C-peptide area under the curve (AUC) at 12 months. Secondary endpoints at 12 months were the change from baseline in the 4 h C-peptide AUC, insulin use, major hypoglycaemic events, and HbA1c concentrations. This trial is registered with ClinicalTrials.gov, number NCT00965458.

FINDINGS

Of 73 patients assessed for eligibility, 33 were randomly assigned to receive alefacept and 16 to receive placebo. The mean 2 h C-peptide AUC at 12 months increased by 0.015 nmol/L (95% CI -0.080 to 0.110) in the alefacept group and decreased by 0.115 nmol/L (-0.278 to 0.047) in the placebo group, and the difference between groups was not significant (p=0.065). However, key secondary endpoints were met: the mean 4 h C-peptide AUC was significantly higher (mean increase of 0.015 nmol/L [95% CI -0.076 to 0.106] vs decrease of -0.156 nmol/L [-0.305 to -0.006]; p=0.019), and daily insulin use (0.48 units per kg per day for placebo vs 0.36 units per kg per day for alefacept; p=0.02) and the rate of hypoglycaemic events (mean of 10.9 events per person per year for alefacept vs 17.3 events for placebo; p<0.0001) was significantly lower at 12 months in the alefacept group than in the placebo group. Mean HbA1c concentrations at week 52 were not different between treatment groups (p=0.75). So far, no serious adverse events were reported and all patients had at least one adverse event. In the alefacept group, 29 (88%) participants had an adverse event related to study drug versus 15 (94%) participants in the placebo group. In the alefacept group, 14 (42%) participants had grade 3 or 4 adverse events compared with nine (56%) participants in the placebo group; no deaths occurred.

INTERPRETATION

Although the primary outcome was not met, at 12 months, alefacept preserved the 4 h C-peptide AUC, lowered insulin use, and reduced hypoglycaemic events, suggesting efficacy. Safety and tolerability were similar in the alefacept and placebo groups. Alefacept could be useful to preserve β-cell function in patients with new-onset type 1 diabetes.

Promising new treatments for psoriasis

Psoriasis is a chronic, proliferative, and inflammatory skin disease affecting 2-3% of the population and is characterized by red plaques with white scales. Psoriasis is a disease that can affect many aspects of professional and social life. Currently, several treatments are available to help control psoriasis such as methotrexate, ciclosporin, and oral retinoids. However, the available treatments are only able to relieve the symptoms and lives of individuals. The discovery of new immunological factors and a better understanding of psoriasis have turned to the use of immunological pathways and could develop new biological drugs against specific immunological elements that cause psoriasis. Biological drugs are less toxic to the body and more effective than traditional therapies. Thus, they should improve the quality of life of patients with psoriasis. This review describes new psoriasis treatments, which are on the market or currently in clinical trials that are being used to treat moderate-to-severe plaque psoriasis. In addition, this paper describes the characteristics and mechanisms in detail. In general, biological drugs are well tolerated and appear to be an effective alternative to conventional therapies. However, their effectiveness and long-term side effects need to be further researched.

Targeting regulatory T cells in the treatment of type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is a T cell-mediated autoimmune disease resulting in islet β cell destruction, hypoinsulinemia, and severely altered glucose homeostasis. T1DM has classically been attributed to the pathogenic actions of auto-reactive effector T cells(Teffs) on the β cell. Recent literature now suggests that a failure of a second T cell subtype, known as regulatory T cells (Tregs), plays a critical role in the development of T1DM. During immune homeostasis, Tregs counterbalance the actions of autoreactive Teff cells, thereby participating in peripheral tolerance. An imbalance in the activity between Teff and Tregs may be crucial in the breakdown of peripheral tolerance, leading to the development of T1DM. In this review, we summarize our current understanding of Treg function in health and in T1DM, and examine the effect of experimental therapies for T1DM on Treg cell number and function in both mice and humans.

Enhanced de novo alloantibody and antibody-mediated injury in rhesus macaques

Chronic allograft rejection is a major impediment to long-term transplant success. Humoral immune responses to alloantigens are a growing clinical problem in transplantation, with mounting evidence associating alloantibodies with the development of chronic rejection. Nearly a third of transplant recipients develop de novo antibodies, for which no established therapies are effective at preventing or eliminating, highlighting the need for a nonhuman primate model of antibody-mediated rejection. In this report, we demonstrate that depletion using anti-CD3 immunotoxin (IT) combined with maintenance immunosuppression that included tacrolimus with or without alefacept reliably prolonged renal allograft survival in rhesus monkeys. In these animals, a preferential skewing toward CD4 repopulation and proliferation was observed, particularly with the addition of alefacept. Furthermore, alefacept-treated animals demonstrated increased alloantibody production (100%) and morphologic features of antibody-mediated injury. In vitro, alefacept was found to enhance CD4 effector memory T cell proliferation. In conclusion, alefacept administration after depletion and with tacrolimus promotes a CD4+memory T cell and alloantibody response, with morphologic changes reflecting antibody-mediated allograft injury. Early and consistent de novo alloantibody production with associated histological changes makes this nonhuman primate model an attractive candidate for evaluating targeted therapeutics.

Aplastic anemia: immunosuppressive therapy in 2010

Acquired aplastic anemia (AA) is the typical bone marrow failure syndrome characterized by an empty bone marrow; an immune-mediated pathophysiology has been demonstrated by experimental works as well as by clinical observations. Immunusuppressive therapy (IST) is a key treatment strategy for aplastic anemia; since 20 years the standard IST for AA patients has been anti-thymocyte globuline (ATG) plus cyclosporine A (CyA), which results in response rates ranging between 50% and 70%, and even higher overall survival. However, primary and secondary failures after IST remain frequent, and to date all attempts aiming to overcome this problem have been unfruitful. Here we review the state of the art of IST for AA in 2010, focusing on possible strategies to improve current treatments. We also discuss very recent data which question the equality of different ATG preparations, leading to a possible reconsideration of the current standards of care for AA patients.

Patients with moderate to severe plaque psoriasis: one year after the European Medicines Agency recommendation of efalizumab suspension

BACKGROUND

In February 19, 2009, the European Medicines Agency (EMA) had recommended the suspension of the marketing authorization for efalizumab after the occurrence of cases of progressive multifocal leukoencephalopathy.

OBJECTIVE

To explore the efficacy of alternative therapies for psoriasis and the health status of patients who discontinued efalizumab.

METHODS

An observational study was performed on 101 patients. After the EMA communication, efalizumab was discontinued in the following 2-3 months. In agreement with the patients, we decided to either prescribe other treatments or none at all.

RESULTS

After 1 year, 11 patients are still not treated, 63 patients are treated with biologics, and 9 patients are treated with systemic conventional therapies.

CONCLUSION

In order to prevent rebound or relapse, various approaches are available, including cyclosporine, methotrexate and biologic therapies. Interestingly, in 11 out of 31 patients who did not receive any systemic drug, psoriasis is still under control, suggesting a long-term effect of efalizumab.

Immunosuppressive therapies in the management of immune-mediated marrow failures in adults: where we stand and where we are going

Immunosuppression is a key treatment strategy for aplastic anaemia (AA) and the related immune-mediated bone marrow failure syndromes (BMFS). For the last 20 years the standard immunosuppressive regimen for AA patients has been anti-thymocyte globulin (ATG) plus ciclosporin A (CyA), which results in response rates ranging between 50% and 70%, and even higher overall survival. However, primary and secondary failures after immunosuppressive therapy remain frequent, and to date all attempts aiming to overcome this problem have been unfruitful. This article reviews the state of the art of current immunosuppressive therapies for AA, focusing on open questions linked to standard immunosuppressive treatment, and on experimental immunosuppressive strategies which could lead to future improvement of current treatments. Specific immunosuppressive strategies employed for other BMFS, such as lineage-restricted marrow failures, myelodysplastic syndromes and large granular lymphocyte leukaemia-associated cytopenias, are also briefly discussed.

The effect of topical corticosteroids in combination with alefacept on circulating T‐cell subsets in psoriasis

BACKGROUND

Novel therapies against psoriasis are emerging. Alefacept is such a treatment. It selectively targets the memory effector population of T cells and thereby diminishes the psoriatic plaques. In some cases, however, the use of alefacept as a monotherapy is not sufficient.

OBJECTIVE

In the present study we investigate the safety and efficacy of adding topical steroids to alefacept treatment during the initial 4 weeks.

METHODS

Peripheral blood was obtained from all patients and the presence of specific T-cell subsets was assessed by flow cytometry. Fourteen patients were included and treated with 15 mg alefacept intramuscularly for a period of 12 weeks. Each of them was randomized to use either betamethasone-dipropionate cream or a vehicle cream during the first 4 weeks of the alefacept course.

RESULTS

Additional topical corticosteroid treatment during the first 4 weeks of alefacept treatment does not have a beneficial effect on the clinical efficacy. Marked changes were seen in the absolute cell counts of various of the analysed T-cell subsets in peripheral blood after 12 weeks of alefacept, either with or without additional local steroid application. The CD45RO+, CD8+CD45RO+, CD8+CD161+, CD4+CD25+, CD4+CLA+ and CD8+CLA+ populations showed a statistically significant decrease immediately after the treatment period. Further analysis revealed that the addition of local steroid therapy to alefacept results in marked decreases of all T-cell subsets analysed in this study, in contrast to the addition of the vehiculum only.

CONCLUSION

Alefacept selectively targets the CD45RO+ lymphocyte population, as well as some other subpopulations of lymphocytes. This effect is independent of the use of additional topical therapy during the first 4 weeks. The extent of the decrease, on the contrary, is dependent on the use of corticosteroids.

T cell targeted immunotherapy for autoimmune disease

Much emphasis has been placed on the so-called "biologics" in the treatment of immune disorders within the last few years. Here we discuss the expanding horizon of potential strategies for immunotherapies targeting T lymphocytes as key effectors and regulators of autoimmunity. We review emerging reagents in a variety of animal models and human disorders that may offer new therapeutic options in current or modified iterations.

Cutaneous sarcoidosis successfully treated with alefacept

BACKGROUND

Sarcoidosis is a systemic granulomatous disease of unknown etiology that affects multiple organ systems, including the pulmonary, lymphatic, skeletal, and integumentary systems. Improved understanding of the intrinsic immunology and molecular biology in sarcoidosis can be applied to the treatment of this disease. Alefacept is a human fusion protein consisting of the extracellular domain of leukocyte function-associated antigen 3 fused with the Fc portion of human immunoglobulin G1. It works by blocking the interaction between antigen-presenting cells and T cells to inhibit activation and by inducing apoptosis of CD4+ T cells. In this case report, we describe a 46-year-old patient with recalcitrant lupus pernio who was successfully treated with alefacept.

OBJECTIVE

To determine whether T-cell inhibition, specifically the use of alefacept, may be used to treat a patient with recalcitrant cutaneous sarcoidosis.

METHODS

Case report.

RESULTS

There was a modest clinical improvement after 8 weeks of intramuscular injections of alefacept.

CONCLUSION

This case report provides further evidence of successful treatment of sarcoidosis with biologic agents directed against T-lymphocyte activation.

Targeting effector memory T cells with the small molecule Kv1.3 blocker PAP-1 suppresses allergic contact dermatitis

The voltage-gated potassium channel Kv1.3 has been recently identified as a molecular target that allows for selective pharmacological suppression of effector memory T (T(EM)) cells without affecting the function of naïve and central memory T cells. We here investigated whether PAP-1, a small molecule Kv1.3 blocker (EC50=2 nM), could suppress allergic contact dermatitis (ACD). In a rat model of ACD, we first confirmed that the infiltrating cells in the elicitation phase are indeed CD8+ CD45RC- memory T cells with high Kv1.3 expression. In accordance with its selective effect on T(EM) cells, PAP-1 did not impair sensitization, but potently suppressed oxazolone-induced inflammation by inhibiting the infiltration of CD8+ T cells and reducing the production of the inflammatory cytokines IFN-gamma, IL-2, and IL-17 when administered intraperitoneally or orally during the elicitation phase. PAP-1 was equally effective when applied topically, demonstrating that it effectively penetrates skin. We further show that PAP-1 is not a sensitizer or an irritant and exhibits no toxicity in a 28-day toxicity study. Based on these results we propose that PAP-1 could potentially be developed into a drug for the topical treatment of inflammatory skin diseases such as psoriasis.

Biologic therapies in clinical development for the treatment of rheumatoid arthritis

The therapeutic objective in patients with rheumatoid arthritis (RA) is reduction of disease activity with an ultimate goal of disease remission. Limitations of currently available disease-modifying antirheumatic drugs and biologic therapies suggest that there remains an unmet need for agents that advance these goals in a greater proportion of patients. Progress in our understanding of the regulatory molecules and pathways that mediate the immune and inflammatory responses necessary for the initiation and perpetuation of RA has led to the identification of new targets for therapy. It is expected that the therapeutic modulation of these targets, which include proinflammatory cytokines, T and B cells, adhesion molecules, chemokines, and intra- and extracellular signaling pathways, can provide new treatment strategies in patients with RA and other autoimmune disorders. Toward this end, a series of novel agents with diverse mechanisms of action are in development. Although many of these agents are still beyond the clinical horizon, several of them have shown promise in recent trials. This article reviews a few of the many treatment strategies currently being evaluated, which are hoped to lead to greater benefits and better disease management in the clinical setting.

Effect of calcipotriol on epidermal cell populations in alefacept-treated psoriatic lesions

BACKGROUND AND OBJECTIVES

The effect of the established antipsoriatic treatment with topical calcipotriol (with a maximum of 100 g per week) in addition to systemic treatment with alefacept, a new biological agent for psoriasis, on epidermal cell populations in the psoriatic lesion was investigated using a combination of the Zenon labelling technique and microscopic image analysis. Epidermal cell populations were measured quantitatively with this sensitive method.

PATIENTS/METHODS

Frozen sections of non-treated psoriatic epidermis and psoriatic epidermis treated with either alefacept intramuscular or alefacept intramuscular in combination with topical calcipotriol for 12 weeks were compared immunohistochemically. Antibodies against keratin 6, 10 and 15 were labelled with the Zenon technique, whereas antibodies against the Ki-67 antigen and beta-1 integrin were covalently Fluorescein Isothiocyanate (FITC)-labelled. Using image analysis, these markers were measured in the epidermis in a standardized manner.

RESULTS AND CONCLUSIONS

Treatment of psoriasis with alefacept resulted in a good clinical response in several patients and in a normalization of epidermal expression of the immunohistochemical parameters for differentiation and proliferation. The addition of topical calcipotriol resulted in a faster clinical improvement with a similar overall clinical response and a similar response of epidermal cell populations as compared to treatment with alefacept monotherapy after 12 weeks of treatment. This study also suggests that the appearance of keratin 15 has a predictive value for the duration of remission. It can be concluded that the addition of a low-dose calcipotriol treatment does not contribute to the clinical efficacy of alefacept, both at the clinical level and with respect to markers for epidermal proliferation and differentiation.

Molecular targets in immune-mediated diseases: focus on rheumatoid arthritis

There are a large number of diseases involving inappropriate activation of the immune system. This review focuses on one such disease, rheumatoid arthritis (RA). Over recent years there has been a dramatic shift in the treatment of RA, in which biological agents, such as monoclonal antibodies and immuno-fusion proteins, have offered the potential to enhance or replace conventional immunosuppressive therapies. This review covers some of the novel biological molecules currently under investigation as potential therapeutic targets in RA. In addition, it covers the genomic and proteomic strategies being used to identify potential new molecular targets for future therapies. Selectively blocking the immune response, in a combination approach blocking not only inflammation but also the adaptive memory response and tissue destruction, holds great promise for the treatment of RA and many other immune-mediated diseases.

Immunosuppressants in advanced clinical development for organ transplantation and selected autoimmune diseases

Immunosuppressants dampen the immune response or restore balance among immune system components. They are primarily used to prevent allograft rejection after organ transplantation and to prevent or treat disease flares in autoimmune diseases. Immunosuppressants available at present include the calcineurin inhibitors (cyclosporin, tacrolimus), antimetabolites (azathioprine, leflunomide, methotrexate, mycophenolate mofetil), antiproliferatives (sirolimus), monoclonal antibodies to T lymphocyte (basiliximab, daclizumab, muromonab-CD3) and anticytokines (anakinra, etanercept, infliximab). The immunosuppressive market grows at a rate of > 10% yearly, with total sales in 2001 of US$2.7 billion. Immunotherapy in transplantation and autoimmune diseases is tending towards the use of multi-drug regimens tailored for the individual patient. At least 23 new immunosuppressants are currently in advanced clinical testing or preregistration, and can be divided into three groups. First, emerging drugs targeting intracellular ligands in immune cells are primarily analogues of currently-marketed agents, which attempt to provide improved pharmaceutical or safety profiles compared with the prototype compound. They are largely being developed in organ transplantation. Second, emerging drugs targeting cell surface ligands on immune cells attempt to antagonise novel molecular sites to interfere with immune cell activation via costimulatory signals, immune cell adhesion to tissues or the vasculature and immune cell trafficking. These agents are being primarily developed in rheumatoid arthritis, psoriasis and/or multiple sclerosis. Finally, emerging drugs acting as anticytokines, which largely follow on from the success of those on the market, by antagonising the function of tumour necrosis factor or a narrow selection of interleukins. All are being assessed in rheumatoid arthritis. Drug development of immunosuppressants is increasingly attempting to intervene in disease progression over the long term. These efforts bring with them trial design and regulatory issues, such as what markers can be used as trial outcome measures, over what duration do trials need to be conducted and what labelling claims are allowed. With the intensive activity in this field, it is likely that several new drugs will reach the market in the coming decade. One caveat, however, is that emerging immunosuppressants that are likely to capture a reasonable share of this increasingly-fragmented market must demonstrate the ability to achieve disease remission or long-term slowing of disease progression.

Dysfunctional blood and target tissue CD4+CD25high regulatory T cells in psoriasis: mechanism underlying unrestrained pathogenic effector T cell proliferation

The balance between regulatory and effector functions is important for maintaining efficient immune responses, while avoiding autoimmunity. The inflammatory skin disease psoriasis is sustained by the ongoing activation of pathogenic effector T cells. We found that a CD4(+) T lymphocyte subpopulation in peripheral blood, phenotypically CD25(high), CTLA-4(+), Foxp3(high) (regulatory T (Treg) cells), is deficient in its suppressor activity in psoriasis. This was associated with accelerated proliferation of CD4(+) responder T cells in psoriasis, the majority of which expressed CXCR3. Nevertheless, criss-cross experiments isolated the defect to psoriatic Treg cells. To examine Treg cells in a nonlymphoid tissue of a human T cell-mediated disease, Treg cells were also analyzed and isolated from the site of inflammation, psoriatic lesional skin. At the regulatory vs effector T cells ratios calculated to be present in skin, however, the psoriatic Treg cell population demonstrated decreased suppression of effector T cells. Thus, dysfunctional blood and target tissue CD4(+)CD25(high) Treg cell activity may lead to reduced restraint and consequent hyperproliferation of psoriatic pathogenic T cells in vivo. These findings represent a critical component of human organ-specific autoimmune disease and may have important implications with regard to the possible therapeutic manipulation of Treg cells in vivo.

From laboratory to clinic: rationale for biologic therapy

Traditional systemic therapy for psoriasis is limited by either lack of efficacy or the long-term side effect profile of the medications used. Newer information about the pathophysiology of the disease has led to new perspectives on developing novel techniques for attacking psoriasis. This article discusses the pathogenesis of psoriasis, looks at the immunologic factors that contribute to forming a psoriatic plaque, reviews how novel biologic therapies are made, and explores how biologics can target each of these specific parts of the immunologic cascade.

Current concepts and review of alefacept in the treatment of psoriasis

Alefacept is a novel biologic agent that selectively targets the memory T-cell population involved in the pathogenesis of psoriasis. Alefacept, administered by intramuscular (IM)or intravenous (IV) bolus injection, is safe and efficacious and improves quality of life ina broad spectrum of psoriasis patients. Disease remissions last approximately 7 months in responders following either IM or IV administration without further treatment. In clinical studies, treatment of patients with psoriasis with up to six courses of alefacept demonstrates the following: no evidence of an increased risk for infection or malignancy;no correlation between rates of infection, malignancy, and circulating CD4+ /CD8+ T-cell counts; and low immunogenicity. A preliminary study evaluating the use of alefacept for the treatment of active psoriatic arthritis parallels the psoriasis experience and supports the premise of targeting T cells as an intervention for this disease. Research continues to examine the use of alefacept in combination with other systemic psoriasis therapies and phototherapy and its potential as a treatment for other T-cell-mediated diseases, such as psoriatic arthritis, alopecia areata, and rheumatoid arthritis.

Sonographic assessment of the liver in children with psoriasis

PURPOSE

The aim of this study was to compare the size and echotexture of the liver in psoriatic and healthy children.

METHODS

In 70 psoriatic and 43 healthy children, longitudinal sonograms of the liver were obtained along standardized section planes defined by the anterior axillary line, medioclavicular line, and midline. The livers' size and echotexture were examined and compared between the study groups.

RESULTS

The measurements of the liver along the 3 section planes were not significantly different between psoriatic and healthy children. Parenchymal liver echogenicity in psoriatic children was neither decreased nor increased.

CONCLUSIONS

No abnormality in size or echotexture of the liver was found in the psoriatic children.

The effect of the combination of calcipotriol and betamethasone dipropionate versus both monotherapies on epidermal proliferation, keratinization and T-cell subsets in chronic plaque psoriasis

Several reports have indicated that the combination of calcipotriol ointment and potent or ultrapotent corticosteroids are more effective and better tolerated, as compared to the monotherapies. The aim of the present study was to find out the effect of combination of calcipotriol ointment once daily and betamethasone dipropionate ointment once daily vs. the effect of twice-daily applications of each of the two treatments as monotherapy during a four-week treatment period. Seven patients with chronic plaque psoriasis were included for treatment with the three treatment schedules. Biopsies were taken before treatment and after four weeks of treatment, and markers for epidermal proliferation (Ki-67) and epidermal differentiation (keratin-10) were studied using a quantitative image analysis, and T-cell subsets in epidermis and dermis (CD4, CD8, CD25, CD45RO, CD45RA, CD94, CD161, and CD2) were studied using immunohistochemical scoring. The most impressive clinical result was reached with the combination. Calcipotriol proved to have a major effect on the proliferation marker Ki-67 and differentiation marker keratin-10, whereas the effect on T-cell subsets was more selective with major reductions of CD45RO(+) and CD8(+) T cells. In contrast, the effect of betamethasone dipropionate on the epidermis was restricted to a normalization of differentiation with a highly significant increase of keratin-10 positive epidermal surface without a significant effect on Ki-67 positive nuclei, and the effect on T-cell subsets was restricted to a reduction of natural killer T-cell receptors designated by CD94 and CD161 in the epidermis. The combination of the two treatments did not affect the proliferation marker Ki-67 and keratinization marker keratin-10, beyond the effect of calcipotriol monotherapy. However, the combination had a profound effect on, virtually, all T-cell subsets, beyond the effect of the monotherapies. It is concluded that the action spectra of calcipotriol and betamethasone on the psoriatic plaque are different and that the combination has effects on T-cell subsets, beyond the addition of the effects of monotherapies.

A novel targeted T-cell modulator, efalizumab, for plaque psoriasis

BACKGROUND

Interactions between leukocyte-function-associated antigen type 1 (LFA-1) and intercellular adhesion molecules are important in the pathogenesis of psoriasis. Efalizumab, a humanized monoclonal antibody, binds to the alpha subunit (CD11a) of LFA-1 and inhibits the activation of T cells.

METHODS

In a phase 3, multicenter, randomized, placebo-controlled, double-blind study, we assign 597 subjects with psoriasis to receive subcutaneous efalizumab (1 or 2 mg per kilogram of body weight per week) or placebo for 12 weeks. Depending on the response after 12 weeks, subjects received an additional 12 weeks of treatment with efalizumab or placebo. Study treatments were discontinued at week 24, and subjects were followed for an additional 12 weeks.

RESULTS

At week 12, there was an improvement of 75 percent or more in the psoriasis area-and-severity index in 22 percent of the subjects who had received 1 mg of efalizumab per kilogram per week and 28 percent of those who had received 2 mg of efalizumab per kilogram per week, as compared with 5 percent of the subjects in the placebo group (P<0.001 for both comparisons). Efalizumab-treated subjects had greater improvement than those in the placebo group as early as week 4 (P<0.001). Among the efalizumab-treated subjects who had an improvement of 75 percent or more at week 12, improvement was maintained through week 24 in 77 percent of those who continued to receive efalizumab, as compared with 20 percent of those who were switched to placebo (P<0.001 for both comparisons). After the discontinuation of efalizumab at week 24, an improvement of 50 percent or more in the psoriasis area-and-severity index was maintained in approximately 30 percent of subjects during the 12 weeks of follow-up. Efalizumab was well tolerated, and adverse events were generally mild to moderate.

CONCLUSIONS

Efalizumab therapy resulted in significant improvements in plaque psoriasis in subjects with moderate-to-severe disease. Extending treatment from 12 to 24 weeks resulted in both maintenance and improvement of responses.

Prevalence of joint disease in patients with psoriasis: implications for therapy

Joint diseases are common among patients with psoriasis. Psoriatic arthritis, the most important of these, can be defined as a rheumatoid factor-negative inflammatory arthritis associated with psoriasis and has emerged as a specific disease independent from rheumatoid arthritis. Psoriatic arthritis is divided into several clinical subsets, which is helpful in differentiating it from other types of inflammatory arthritis. The prevalence of arthritis in patients with psoriasis may be far higher than the previously accepted average of 7%. In a recent study of 5,795 members of the Nordic Psoriasis Associations, the prevalence was found to be 30%. Arthritis has a significant impact on quality of life in patients with psoriasis. These factors should be recognised as they have implications for therapy, since a number of drugs can delay or stop joint damage when given in time. This also applies to the new biologic agents, although at present these therapies are generally restricted to patients non-responsive to other available drugs. Alone or in combination, the new drugs may achieve higher response rates and have better safety profiles than older therapies. However, long-term experience is still lacking and, unfortunately, the new drugs will be far from affordable by all for some time to come.

Systemic therapies for psoriasis: understanding current and newly emerging therapies

The treatment of moderate to severe psoriasis is a rapidly expanding area. Recent insights into the pathogenesis of this disease as a T-cell mediated process has led to a greater understanding of the mechanisms of action of conventional FDA-approved systemic therapies such as methotrexate, cyclosporine, acitretin, and psoralen with ultraviolet A phototherapy. It has also led to the development of rationally targeted therapies against key components of the immune process critical in the generation of the psoriatic plaque. Safety and efficacy data from clinical studies of 4 biologic agents furthest along in their development are reviewed. These results are promising, adding to the armamentarium for treating this disease.

Stellenwert von Biologics in der Psoriasis-Therapie: Ein Konsensus-Papier der Arbeitsgruppe Psoriasis, Arbeitsgemeinschaft dermatologische Forschung. The role of biologics into the management of psoriasis: A consensus paper by the Psoriasis Study Group, Arbeitsgemeinschaft Dermatologische Forschung

About 20% of all psoriasis patients require photo- and/or systemic therapy because of the severity of their disease. Side effects, contraindications, insufficient clinical responses, and lack of long-term efficacy underline the need for novel and improved anti-psoriatic therapies. In recent years, the technology has been established to generate therapeutic molecules from living cells capable of inhibiting disease-relevant mediators or cell-cell interactions. Several of these so-called biologics interfering with key steps in the immunopathogenesis of psoriasis have the potential to meet this need with regard to treating moderate to severe psoriasis. Here, the Psoriasis Study Group of the Arbeitsgemeinschaft Dermatologische Forschung (ADF) analyses the established anti-psoriatic treatment modalities. With the shortcomings of these options in mind, biologics with an immediate relevance for clinical application in the treatment of psoriasis are discussed. The focus is on their potential medical advantages along with safety aspects. Moreover, legal and economical aspects with an impact on the use of biologics are addressed.

Novel biological immunotherapies for psoriasis

Psoriasis is a common skin disease affecting 1 - 3% of the white population. Although its physiopathogenesis still remains poorly understood, recent data suggest a key role played by memory T cells in the genesis of skin and joint lesions. Recent developments in the understanding of cellular mechanisms underlying psoriasis and in biotechnologies have given rise to a generation of biological agents that have shown clinical efficacy in treating psoriasis. These agents, including chimeric antibodies, fusion proteins and recombinant interleukins, specifically target the activated memory T cells directly involved in the development of psoriasis lesions and inhibit their action either directly or through inhibition of pro-inflammatory cytokines. Compared with conventional systemic treatments, they show a better safety profile and allow durable remissions. Some of these agents were very recently marketed for the treatment of psoriasis and hopefully others will follow. These biologicals have opened a new era for the management of this disease; they are reviewed in this article, based on data available in the literature.