Antigen-based therapy with glutamic acid decarboxylase (GAD) vaccine in patients with recent-onset type 1 diabetes: A randomised double-blind trial

Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
The Lancet (Impact Factor: 45.22). 06/2011; 378(9788):319-27. DOI: 10.1016/S0140-6736(11)60895-7
Source: PubMed

ABSTRACT Glutamic acid decarboxylase (GAD) is a major target of the autoimmune response that occurs in type 1 diabetes mellitus. In animal models of autoimmunity, treatment with a target antigen can modulate aggressive autoimmunity. We aimed to assess whether immunisation with GAD formulated with aluminum hydroxide (GAD-alum) would preserve insulin production in recent-onset type 1 diabetes.
Patients aged 3-45 years who had been diagnosed with type 1 diabetes for less than 100 days were enrolled from 15 sites in the USA and Canada, and randomly assigned to receive one of three treatments: three injections of 20 μg GAD-alum, two injections of 20 μg GAD-alum and one of alum, or 3 injections of alum. Injections were given subcutaneously at baseline, 4 weeks later, and 8 weeks after the second injection. The randomisation sequence was computer generated at the TrialNet coordinating centre. Patients and study personnel were masked to treatment assignment. The primary outcome was the baseline-adjusted geometric mean area under the curve (AUC) of serum C-peptide during the first 2 h of a 4-h mixed meal tolerance test at 1 year. Secondary outcomes included changes in glycated haemoglobin A(1c) (HbA(1c)) and insulin dose, and safety. Analysis included all randomised patients with known measurements. This trial is registered with, number NCT00529399.
145 patients were enrolled and treated with GAD-alum (n=48), GAD-alum plus alum (n=49), or alum (n=48). At 1 year, the 2-h AUC of C-peptide, adjusted for age, sex, and baseline C-peptide value, was 0·412 nmol/L (95% CI 0·349-0·478) in the GAD-alum group, 0·382 nmol/L (0·322-0·446) in the GAD-alum plus alum group, and 0·413 nmol/L (0·351-0·477) in the alum group. The ratio of the population mean of the adjusted geometric mean 2-h AUC of C-peptide was 0·998 (95% CI 0·779-1·22; p=0·98) for GAD-alum versus alum, and 0·926 (0·720-1·13; p=0·50) for GAD-alum plus alum versus alum. HbA(1c), insulin use, and the occurrence and severity of adverse events did not differ between groups.
Antigen-based immunotherapy therapy with two or three doses of subcutaneous GAD-alum across 4-12 weeks does not alter the course of loss of insulin secretion during 1 year in patients with recently diagnosed type 1 diabetes. Although antigen-based therapy is a highly desirable treatment and is effective in animal models, translation to human autoimmune disease remains a challenge.
US National Institutes of Health.

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    • "The most studied of these are proinsulin and GAD65, both of which are very effective in reversing and preventing diabetes in non-obese diabetic (NOD) mouse model of T1D, though somewhat disappointing when translated to clinical trials [13] [14]. A recent example was vaccination with GAD-alum which induced regulatory T cells [15] and delayed the loss of glucose-stimulated C-peptide levels in patients treated soon after diagnosis, but did not prevent the disease [16] [17]. While disheartening, these results indicate that autoantigen-based therapies in humans can restore immune balance when administered in the right context and with an optimal regimen. "
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    ABSTRACT: Type 1 diabetes (T1D) is a metabolic disease that is initiated by the autoimmune destruction of pancreatic insulin-producing beta cells that is accompanied by the development of antigen-specific antibodies and cytotoxic T lymphocytes (CTLs). Several studies have shown that vaccination with diabetic autoantigens provides some protection against this process. In this report we describe a new oral vaccine that utilizes live attenuated Salmonella for simultaneous delivery of autoantigens in conjunction with immunomodulatory cytokine genes to immune cells in the gut mucosa. Recent data showed that live attenuated Salmonella is a safe, simple and effective vector for expression of antigens and cytokines by antigen-presenting cells (APCs) of gut-associated lymphatic tissue (GALT). This novel strategy was tested by fusion of the diabetic autoantigen preproinsulin with Salmonella secretory effector protein (SseF) of pathogenicity island-2 (SPI2). In this way the autoantigen is only expressed inside the host immune cells and translocated to the host cell cytosol. In addition Salmonella was used to deliver the gene for the immunomodulatory cytokine transforming growth factor beta (TGFβ) for host cell expression. Oral co-vaccination of 8 week-old non-obese diabetic (NOD) mice with three weekly doses of both the autoantigen and cytokine significantly reduced the development of diabetes, improved the response to glucose challenge, preserved beta cell mass, and reduced the severity of insulitis compared with controls and autoantigen alone. Combination therapy also resulted in increased circulating levels of IL10 four weeks post-vaccination and IL2 for 12 weeks post-vaccination, but without effect on proinflammatory cytokines IL6, IL12(p70), IL17 and IFNγ. However, in non-responders there was a significant rise in IL12 compared with responders. Future studies will examine the mechanism of this vaccination strategy in more detail. In conclusion, Salmonella-based oral vaccines expressing autoantigens combined with imunomodulatory cytokines appears to be a promising therapy for prevention of T1D.
    Vaccine 03/2014; 32(20). DOI:10.1016/j.vaccine.2014.02.070 · 3.49 Impact Factor
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    • "Human clinical investigations in recent-onset T1D patients using alum-formulated hGAD65 therefore considered the safety and efficacy of a treatment regimen consisting of prime and boost injections with different doses of the protein (Lernmark and Agardh 2005). Although these studies showed that treatment was safe, the efficacy data were equivocal suggesting that inducing tolerance in humans remains a challenge (Wherrett et al. 2011; Ludvigsson et al. 2012). A further trial, involving genetically-predisposed children and young adults with multiple islet cell autoantibodies , is currently exploring the ability of alumformulated hGAD65 to prevent the onset of disease (NCT01122446). "
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    ABSTRACT: The 65-kDa isoform of human glutamic acid decarboxylase (hGAD65) is a major diabetes autoantigen that can be used for the diagnosis and (more recently) the treatment of autoimmune diabetes. We previously reported that a catalytically-inactive version (hGAD65mut) accumulated to tenfold higher levels than its active counterpart in transgenic tobacco plants, providing a safe and less expensive source of the protein compared to mammalian production platforms. Here we show that hGAD65mut is also produced at higher levels than hGAD65 by transient expression in Nicotiana benthamiana (using either the pK7WG2 or MagnICON vectors), in insect cells using baculovirus vectors, and in bacterial cells using an inducible-expression system, although the latter system is unsuitable because hGAD65mut accumulates within inclusion bodies. The most productive of these platforms was the MagnICON system, which achieved yields of 78.8 μg/g fresh leaf weight (FLW) but this was substantially less than the best-performing elite transgenic tobacco plants, which reached 114.3 μg/g FLW after six generations of self-crossing. The transgenic system was found to be the most productive and cost-effective although the breeding process took 3 years to complete. The MagnICON system was less productive overall, but generated large amounts of protein in a few days. Both plant-based systems were therefore advantageous over the baculovirus-based production platform in our hands. Electronic supplementary material The online version of this article (doi:10.1007/s11248-013-9749-9) contains supplementary material, which is available to authorized users.
    Transgenic Research 10/2013; 23(2). DOI:10.1007/s11248-013-9749-9 · 2.28 Impact Factor
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    • "Next, in order to confirm that GAD-alum immunizations induced the production of anti-GAD65 autoantibodies as was shown in human patients [21] [23], we performed serum titrations at 4 weeks post-infection in RIP-GP mice that were treated three times with 2 mg GAD-alum or alum alone. Our findings show that GAD-alum treated individuals harbored significantly increased titers of GAD65-specific IgG autoantibodies compared to mice treated with placebo (Fig. 2D), suggesting that our administration regimen effectively led to GAD-specific humoral responses. "
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    ABSTRACT: Antigen-specific interventions are desirable approaches in Type 1 Diabetes (T1D) as they can alter islet-specific autoimmunity without systemic side effects. Glutamic acid decarboxylase of 65 kDa (GAD65) is a major autoantigen in type 1 diabetes (T1D) and GAD-specific autoimmunity is a common feature of T1D in humans but also in mouse models of the disease. In humans, administration of the GAD65 protein in an alum formulation has been shown to reduce C-peptide decline in recently diagnosed patients, however, these observations were not confirmed in subsequent phase II/III clinical trials. As GAD-based immune interventions in different formulations have successfully been employed to prevent the establishment of T1D in mouse models of T1D, we sought to analyze the efficacy of GAD-alum treatment and the effects on the GAD-specific immune response in two different mouse models of T1D. Consistent with the latest clinical trials, mice treated with GAD-alum were not protected from diabetes, although GAD-alum induced a GAD-specific Th2-deviated immune response in transgenic rat insulin promoter-glycoprotein (RIP-GP) mice. These observations underline the importance of a thorough, preclinical evaluation of potential drugs before the initiation of clinical trials.
    Journal of Autoimmunity 06/2013; 44. DOI:10.1016/j.jaut.2013.05.002 · 7.02 Impact Factor
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