Present and Future of Combination Therapy of Autoimmune Diseases

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Present and future of combination therapy of autoimmune diseases

disease remission, enabling changes in dosing and ‘A dual therapeutic strategy targeting scheduling of those drugs with the least conven- the dominating proinflammatory ient safety profile, leading certainly to a more milieu as well as the more specific individualized approach to medicine and open- immune response is, in our view, ing the possibility of identifying a strategy leading especially promising.’ to long-lasting remission.

Treatment regimens for rheumatological diseases Combination of nonbiologics have changed considerably over the past 20 years. It has become common practice, that patients are To date, treatment of rheumatoid arthritis (RA) started on disease-modifying antirheumatic mainly focused on the inflammatory pathogenic drugs (DMARDs) therapy early in the course of component of the disease. Significant progress in their disease. In order to achieve synergy without the induction of disease remission has been subsequent increase in toxicity, long-term remis- achieved by the use of powerful immunosuppres- sion and slowing of radiological damage, the sants and cytostatic drugs, such as corticosteroids, combination of several DMARDs with different methotrexate (MTX) and leflunomide, in the mechanisms of action was tested and found to be early stage of the disease [1,2]. Biologics have effective in some combinations [5,6]. For instance, recently been added for treatment-resistant dis- in two open-label randomized trials in patients ease, more specifically targeting components that with early RA, the combination of MTX, sulfa- play a role in the disease pathogenesis [3,4]. Unfor- salazine, hydroxychloroquine (HCQ) and pred- tunately, persistent disease remission can only be nisolone demonstrated greater clinical achieved as long as the drugs are administered, improvement and significantly less radiographic and only then can progression of joint damage be progression compared with a single DMARD prevented. In addition, since most of these agents with or without prednisone [2,7]. Many other induce a generalized and nonspecific inhibition of combinations are used in common practice, with immune response and inflammation, they can a general direct correlation between increased cause considerable immunodepression, leading to clinical efficacy and overlapping undesired complications that prompted US FDA to formu- effects, which limit the use of such combinations. late black-box warnings for some of these prod- The underlying reason for the synergistic effect ucts. A more specific modulation of the immune of these DMARDs is not fully known at present. Sarah TA Roord, response could theoretically overcome these pit- This effect may may be partly due to the influ- Berent J Prakken & falls. Some of these novel strategies are in the ence on each other’s pharmacokinetics; for exam- Salvatore Albani † clinical development stage. ple, HCQ leads to slower clearance and uptake †Author for correspondence University of California, The combination of treatment strategies with with a greater area under the curve for MTX in San Diego, Departments of different and complementary mechanisms of patients taking the combination of HCQ and Medicine & Pediatrics, action is likely to be more successful and is thus MTX [8]. The synergy may also be mechanistic 9500 Gilman Drive, being introduced into the standard of practice; by and affect both the adaptive and innate arms of La Jolla, CA 92093-0731, USA acting complementarily or synergistically, they can the immune response. For instance, MTX, as a Tel.: +1 858 534 0394; enhance efficacy. Cost and toxicity can be folate inhibitor, acts on rapidly proliferating cells, Fax: +1 858 822 5666; decreased, owing to the opportunity to administer which are purportedly composing the pool of [email protected] lower amounts of drugs than when they are given effector cells that may fuel autoimmune inflam- separately. Combination of nonbiologics, currently mation. Conversely, HCQ is an inhibitor of approved biologics and novel biologics will be dis- intracellular processes involved in antigen presen- cussed in this editorial. A dual therapeutic strategy tation, thus potentially affecting the repertoire of targeting the dominating proinflammatory milieu autoantigens available to effector cells [9]. as well as the more specific immune response is, in Unfortunately, a proportion of patients still our view, especially promising. Induction of spe- do not respond sufficiently to DMARD therapy, cific immune tolerance may provide a long-lasting and complementary approaches are needed.

Major disadvantages of the use of DMARDs are significantly, compared with MTX or that they are not specific (and therefore lead to anti-TNFα treatment alone [12–20]. The combi- side effects) and that they must be administered nation treatments led to a decrease in disease continuously to retain efficacy. activity, reduction of disability, an increase in remission rates and even a decrease in progres- Combination of currently sion of joint damage. Unfortunately, the exact approved biologics mechanism underlying this synergistic effect is Greater success with fewer side effects can be not currently known, but may be explained in expected by more specifically targeting pro- part by a decreased amount of neutralizing anti- inflammatory cytokines that are known to play a bodies against TNF antagonists [21]. Further- role in the autoimmune process, such as tumor more, knowledge on the influence of MTX on necoris factor (TNF)α, interleukin (IL)-1 or -6. T cells and the inflammatory process has been Several biological agents have been identified expanding in recent years, and may also provide that can block these cytokines: some explanation for the combinatory effect of • Enbrel (Etanercept®), a soluble TNF receptor MTX with anticytokine treatment. MTX pro- fusion protein, targets TNFα; motes the release of the endogenous anti- • Remicade (Infliximab®), a chimeric anti- inflammatory mediator adenosine, presumably TNFα antibody, targets TNFα; through its capacity to increase intracellular 5-aminoimidazole-4-carboxamide ribonucle- •Humira (Adalimumab®), a recombinant otide (AICAR) concentrations [22]. Adenosine human anti-TNFα antibody, targets TNFα; has a central role in regulation of inflammatory ® • Kineret (Anakinra ), an IL-1 receptor responses, one of which is the contribution to antagonist (IL1-RA), neutralizes IL-1; the resolution of inflammation, both by down- •MRA® (a humanized IL-6 receptor antibody) regulating macrophage activation and by targets IL-6. advancing T-helper (Th)2 versus Th1 cell The use of these agents has shown clinical effi- development [23]. Direct evidence for the pro- cacy in several clinical trials, but the fact that the motion of a more anti-inflammatory environ- effects are only temporary, their cost is high and ment by MTX was gained in early RA patients, severe side effects may occur, such as an increase where a decrease in T-cell-derived TNFα was in serious infections and possibly lymphomas observed, together with an increase in IL-10- due to anti-TNFα treatment, is hampering their producing T cells [24]. In in vitro experiments, success [3,10]. MTX was demonstrated to increase IL-10 and The potential for additive or synergistic effects -4 gene transcription as well as decrease IFNγ of two biologics has been tested in the treatment gene transcription [25]. Therefore the combina- of RA by adding kineret to treatment with tion of blocking proinflammatory cytokines by enbrel. However, no additional clinical effect was anticytokine biologics with the promotion of a demonstrated, whereas an increased safety risk more anti-inflammatory environment by MTX did become apparent, due to higher incidence of may work synergistically. serious infections, injection site reactions and Hence, an important step towards obtaining neutropenia [11]. Therefore, the combination of disease remission and slowing of radiological two anticytokine biologics is not recommended. damage has been obtained by combining several Conversely, a field with great potential is the DMARDs or combining MTX and anticytokine combination of biologics that target different biologics. However, the effects only last while the immunopathogenic pathways; therefore exploit- drugs are administered. ing a potential complementarity in mechanism of action. However, these approaches are at the Combination of currently approved initial stage of clinical testing to ascertain both biologics with novel biologics efficacy and tolerability. The induction of specific immune tolerance would ideally spare the patient generalized Combination of nonbiologics with immune suppression and could be expected to currently approved biologics provide a long-lasting effect (and maybe even a Promising results were obtained when combining cure) that is devoid of side effects. The induction MTX with a biological agent. The combination of immune tolerance requires the identification of MTX with anti-TNFα or IL-1RA treatment is of the appropriate target. Efforts at inducing tol- found to improve the clinical outcome erance independent of a specific antigenic target

650 Future Rheumatol. (2006) 1(6) Combination therapy of autoimmune diseases – EDITORIAL

are mainly based on molecules interfering with physiological response, which involves both the either T (CD3 or CD80/CTLA-4) or B cells adaptive and the innate arms of the immune sys- (CD20/CD22). These attempts have led to very tem [37–39]. Such a response contributes to the encouraging results, and some of these drugs are clearing of a possible pathogen invasion, but also already available on the market. In recent onset induces increased availability of self-HSP-derived Type 1 diabetes, two humanized anti-CD3 peptides through cellular stress. These peptides monoclonal antibodies were able to maintain then form a new target for the immune system and residual β cell function better than placebo or a induce self-perpetuating cycles of inflammation, control group, as demonstrated by increased C fueled by the self-antigens and self-reactive T cells. peptide responses and decreased insulin needs. We have previously demonstrated, that HSP pep- Short-term treatment even produced lasting tides are recognized by T cells with regulatory effects for up to 2 years [26,27]. Orencia (Abata- function, which are then capable of preventing cept®), a recombinant cytotoxic T-lymphocyte further tissue damage. If such regulatory function antigen (CTLA)4-immunoglobulin (Ig) fusion is impaired, loops of inflammation continue and protein, blocks the costimulatory signal required autoimmune arthritis prevails [40,41]. for T-cell activation by competing with CD28 for CD80 and CD86 binding. It demonstrated ‘Promising results of antigen-specific effectiveness in active RA patients, in improve- immunomodulation by HSP in ment of signs and symptoms of disease, physical experimental disease models of function and the quality of life over a period of arthritis and Type 1 diabetes 12 months in two Phase II studies [28,29]. In a warranted subsequent clinical trials in Phase III randomized trial, it also demonstrated human disease.’ clinical and functional benefits in nonresponders to TNFα therapy [30]. Although the role of Promising results of antigen-specific immuno- B cells in RA is not fully understood, selective modulation by HSP in experimental disease depletion of B cells by a monoclonal antibody models of arthritis and Type 1 diabetes war- against CD20, rituxan (Rituximab®), led to sus- ranted subsequent clinical trials in human dis- tained clinical improvement in an open label ease [42,43]. In RA, we have recently reported the study [31]. In a subsequent randomized, double- results of a Phase I/IIa clinical trial with a dnaJ- blind, controlled study in 161 RA patients, treat- derived peptide, dnaJP1, administered orally to ment with rituxan, alone or in combination with 15 patients with early, active disease [44]. Interest- cyclophosphamide or MTX, led to significant ingly, with this treatment, we were able to induce improvement of disease symptoms [32]. This cat- immune deviation from proinflammatory to egory of molecules represents a significant step modulatory T-cell responses, leading to signifi- forward with their mechanism of action, because cant reduction in TNFα and IFNγ production, in most cases they aim to modulate certain and an increase in IL-10 and -4. These effects aspects of adaptive immunity rather than were mediated via restoration of function of suppress an individual pathway (i.e., a cytokine). CD4CD25 bright regulatory T cells (Treg), pro- Another approach would be induction of toler- ducing IL-10 and expressing FOXP3. Recently, ance using an antigen. However, the search for the we completed the Phase II clinical trial with disease-triggering antigen has not been successful dnaJP1 [Submitted]. This study focused on safety to date, and attempts to induce tolerance to candi- and clinical efficacy of the drug. It involved dates in this respect, such as chicken and bovine 160 patients who received dnaJP1 or placebo Type II collagen and human cartilage glycoprotein orally once per day for 6 months. The dnaJP1 (HCgp)39, major constituents of articular carti- peptide treatment demonstrated encouraging lage, were also not encouraging [33–36]. In fact, we clinical and immunological effects, suggesting feel that the focus of antigen-specific therapy that induction of immune tolerance to an should move away from the one disease-triggering inflammatory ubiquitous antigen may translate antigen and should focus mainly on key players at into clinical improvement of the disease. the site of inflammation, which play a role in dis- Due to safety and specificity in mechanism of ease perpetuation. Heat-shock proteins (HSPs) are action, epitope-specific immunotherapy has the present in all cells and are upregulated during profile of an ideal ‘work with’ approach. As such, stress. As ubiquitous and bacterial-derived prod- it could exploit synergy and complementarity in ucts, HSP-derived peptides are perceived as a dan- mechanisms of action with both biologics and ger signal and elicit a default proinflammatory more traditional DMARDs. www.futuremedicine.com 651 EDITORIAL – Roord, Prakken & Albani

We have obtained the first results in the combi- and numbers in RA patients [49–51]. Additionally, nation of anti-TNFα therapy and antigen-specific anti-TNFα treatment was shown to induce a immunomodulation to an HSP60 peptide in an shift to a more anti-inflammatory cytokine pro- experimental form of arthritis: adjuvant arthritis file in peripheral blood mononuclear cells (AA). AA is a T-cell-dependent disease that can be (PBMCs) and T cells of RA patients [52]. In non- passively transferred by a T-cell clone that is spe- obese diabetic mice, it was demonstrated that cific for the 180–188 amino acid sequence of anti-CD3 treatment led to a decrease in the mycobacterial HSP60 [45,46]. In previous studies, amount of autoaggressive T cells and an expan- we demonstrated that nasal administration of sion of CD4+CD25+ cells in draining lymph peptide 180–188 after the induction of AA is nodes. Disease suppression was mediated mildly effective [43]. Interestingly, by giving a sin- through production of TGFβ [53]. gle low dose of enbrel before mucosal tolerance As aforementioned, epitope-specific immuno- induction to HSP60 peptide 180–188, significant therapy also has the potential to act in synergy suppression of arthritis was observed to the same with more traditional DMARDs. In our Phase II extent as a full course of enbrel therapy [47]. This trial with dnaJP1 in human RA, we unexpect- implies that lower doses of anti-TNFα can be edly obtained the first results of combination given, resulting in lower cost and less long-term treatment of a DMARD and mucosal tolerance side effects. Interestingly, two distinctly different induction. Interestingly, the clinical effect of immunological mechanisms were at the basis of dnaJP1 was clearly enhanced in patients using equivalent clinical suppression of arthritis when hydroxychloroquine (HCQ). HCQ is tradition- comparing full dose enbrel therapy with the com- ally an antimalarial drug that, due to its immu- bination treatment of anti-TNFα and 180–188 nomodulatory effects, is also used in the peptide. Where anti-TNFα treatment induced treatment of RA. The explanation of the mainly immune suppression, combination treat- enhanced effect of dnaJP1 tolerance induction ment was able to induce active modulation due to HCQ, may be partly because it is known through induction of IL-10 production by effec- to decrease TNFα and IL-6 production. HCQ’s tor T cells, as well as the induction of main effect is exerted through blockade of the CD4+CD25+ regulatory T cells, again producing processing of proteins by antigen-presenting cells IL-10 and expressing FOXP3. (APCs) [9,54,55]. This creates an environment of low self-presentation of proteins, whereby the ‘Immune tolerance may still be the dnaJP1 peptide might be more easily presented, ultimate objective in the treatment of as it does not need to be processed in order to be autoimmune diseases.’ presented by APCs. In this way, such peptides may have a greater impact on the regulatory Similarly promising results were recently pub- immune system. lished by Bresson and colleagues in experimental Combination of MTX with antigen-specific diabetes [48]. By combining anti-CD3 and intra- tolerance induction may also be beneficial. MTX nasal proinsulin peptide treatment, recent onset administration may create a better milieu for diabetes could be reversed more potently than antigen-specific immunomodulation, by creating when anti-CD3 or the peptide was given alone. an anti-inflammatory environment and maybe This combination treatment induced Tregs; the even a more tolerogenic microenvironment via level of CD4+CD25+FOXP3+ cells increased and its action on rapidly proliferating effector T cells insulin-specific production of IL-10, TGFβ and and the decrease in TNFα production [23,24]. IL-4 by Tregs was enhanced. The Tregs were capable of suppressing autoaggressive CD8+ Conclusion & future perspective responses in vitro. Furthermore, adoptive trans- The combination of different treatments, espe- fer of the peptide-specific Tregs suppressed dis- cially of DMARDs or anticytokine biologics ease in recent onset diabetic recipients to the with novel biologics, appears to be effective same extent as in the donors. through synergistic, as well as complementary, The reason the induction of tolerance is facili- working mechanisms. These approaches may tated by the combination with anti-TNFα and implicate important changes in the future anti-CD3, may be partly because both have been management of autoimmunity. demonstrated to create a tolerogenic environ- Immune tolerance may still be the ultimate ment. Several studies have demonstrated that objective in the treatment of autoimmune dis- anti-TNFα treatment can improve Treg function eases. The combination treatment approach may

652 Future Rheumatol. (2006) 1(6) Combination therapy of autoimmune diseases – EDITORIAL

exploit the strengths of complementary drugs to responding to certain cocktails of drugs; and reduce the chances of developing side thereby providing an important step towards effects. This approach, which is associated with a individualized medicine. more focused and effective approach toward Lastly, the complementarities in mechanisms modulation of adaptive immunity, may render of action and the diverse potency of various true immune tolerization attainable. DMARDs and biologics may eventually lead to a Secondly, the increasing knowledge of the progressive treatment design, where various pathophysiology of disease may enable the drugs may be used at different times. In such a choice of different associations of drugs, for protocol, DMARDs and anticytokine biologics example, based on genetic and pathological pat- can be applied to induce disease remission, fol- terns. This may lead to the identification of lowed by epitope-specific therapy in order to subgroups of patients who may be more prone maintain it.

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54. Savarino A, Boelaert JR, Cassone A, Affiliations • Berent J Prakken, MD, PhD Majori G, Cauda R: Effects of chloroquine • Sarah TA Roord, MD Wilhelmina Children’s Hospital, Department of on viral infections: an old drug against University of California, San Diego,Departments Pediatric Immunology, University Medical today’s diseases? Lancet Infect. Dis. 3(11), of Medicine &Pediatrics, 9500 Gilman Drive, Center Utrecht, The Netherlands 722–727 (2003). La Jolla, CA 92093-0731, USA Tel.: +31 302 503 316; 55. van den Borne BE, Dijkmans BA, and, Fax: +31 302 505 350; de Rooij HH, Le CS, Verweij CL: Wilhelmina Children’s Hospital, Department of [email protected] Chloroquine and hydroxychloroquine Pediatric Immunology, University Medical •Salvatore Albani, MD PhD equally affect tumor necrosis factor-α, Center Utrecht, The Netherlands University of California, San Diego, interleukin 6, and interferon-γ production Tel.: +31 302 504 595; Departments of Medicine &Pediatrics, by peripheral blood mononuclear cells. Fax: +31 302 505 350; 9500 Gilman Drive, La Jolla, J. Rheumatol. 24(1), 55–60 (1997). [email protected] CA 92093-0731, USA Tel.: +1 858 534 0394; Fax: +1 858 822 5666; [email protected]