New Therapeutic Targets in ANCA-associated Vasculitis
Maria Prendecki MBBS PhD and Stephen P. McAdoo MBBS PhD

Correspondence
Dr Stephen McAdoo, Centre for Inflammatory Disease, Department of Immunology and Inflammation, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
Email [email protected], Tel +44 (0)20 8383 3152, Fax +44 (0)20 8383 2062

Acknowledgements
We acknowledge support from the National Institute for Health Research Imperial Biomedical Research Centre.

Disclosures
SPM has received honoraria from Rigel Pharmaceuticals and Celltrion Healthcare.

Abstract word count: 170 Word count: 3759
Figures: 1
Table: 1

This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/ART.41407

Accepted Article
Abstract

Anti-neutrophil cytoplasm antibody (ANCA)- associated vasculitis (AAV) is a rare systemic auto- immune disease characterised by necrotizing inflammation of predominantly small blood vessels and the presence of circulating ANCA directed against myeloperoxidase (MPO) or proteinase-3 (PR3). Current treatment strategies for severe disease, supported by the findings of several well- coordinated randomised control trials, aim to induce remission with high-dose glucocorticoids and either rituximab or cyclophosphamide, followed by relapse prevention with a period of sustained low-dose treatment. This approach has dramatically improved outcomes in AAV, however a significant proportion of patients experience serious treatment-related side effects or suffer relapse. Recent advances in our understanding of disease pathogenesis has led to the identification of novel therapeutic targets which may address these problems, including those directed at the aberrant adaptive autoimmune response (B and T cell directed treatments) and those targeting innate immune elements (complement, monocytes, neutrophils). It is anticipated that these novel treatments, used alone or in combination, will lead to more effective and less-toxic treatment regimens for patients with AAV in the future.

Accepted Article
Introduction

The anti-neutrophil cytoplasm antibody- (ANCA-) associated vasculitides (AAV) are a group of rare systemic inflammatory diseases that includes granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic GPA (EGPA). They are associated with the presence of autoantibodies to myeloperoxidase (MPO) or proteinase-3 (PR3), which are thought to play a pathogenic role, although approximately 10% of patients are ANCA negative, and they have similar clinical features to those who are ANCA positive (1). They are multi-system diseases that, in common, are characterised by necrotizing inflammation of predominantly small blood vessels, though clinical presentation can vary widely, both in disease severity and spectrum of organ involvement.

Historically, outcomes in patients with AAV were poor, with up to 80% mortality at one year prior to the use of immunosuppressive treatment. This was transformed with the introduction of cyclophosphamide, used in combination with glucocorticoids, in the 1970s. Since then, there has been decade upon decade improvements in patient outcome (2, 3), reflecting a combination of improved general medical care, earlier diagnosis, and more refined immunosuppressive regimens that have reduced toxicity from long-term cyclophosphamide use. These have been informed by a number of well-designed and collaborative clinical trials, and based on their findings current guidelines stratify treatment depending on severity and phase of disease, usually with an initial period of intense immunosuppression to induce remission (often with cyclophosphamide or rituximab), followed by prevention of relapse with a period of sustained low-dose maintenance treatment (with drugs such as azathioprine, MMF or rituximab) (4).

With this approach, most patients now achieve remission during the first six months of treatment, and survival is estimated to be > 90% at one year. However, unmet treatment needs remain: most deaths in the first year are now attributed to side effects of treatment, particularly infection. During long-term follow up, therapy-related adverse events remain problematic, including malignancy and cardiovascular disease, and underscoring the need to refine treatment regimens further (5, 6). In addition, approaches that can induce more sustained remissions, thus avoiding the accrual of damage caused by disease relapse and its retreatment, are badly needed in this patient population.

Accepted Article
Advances in our understanding disease pathogenesis – related to both the aberrant adaptive T and B response that underlie this autoimmune disease, and to the role of innate immune components, including neutrophils, monocytes and complement, as mediators of vascular damage – provide an opportunity to identify more specific, less toxic treatment for AAV. Many novel therapeutic agents are being investigated in pre-clinical and early phase clinical studies and in this review we summarise possible future therapeutic options (Figure 1) (7-10). EGPA, having distinct pathogenesis and therapeutic approaches, is not included here.

Targeting B cells

The emergence of rituximab as an effective induction and remission-maintenance treatment is arguably the most significant development in the management of AAV since the introduction of cytotoxic therapy almost half a century ago. B cells are clearly central to disease pathogenesis: they produce ANCA; activated B cell numbers have been shown to correlate with disease activity (11); and B cell repopulation after rituximab, and possibly their phenotype, may predict relapse (12).

Several second generation anti-CD20 drugs are in development – these differ from rituximab in their epitope specificity, pharmacokinetics, and ability to induce either complement or antibody- dependent cytotoxicity and apoptosis, which in turn may impact the rapidity, depth and duration of their depleting effect of the circulating and tissue B cell pool. Ofatumumab, a fully humanized anti-CD20 mAb, has been tested in one small case series of patients with AAV where it showed therapeutic benefit, however none of these second generation agents have been tested in RCT in AAV (13). Obinutuzumab, which has increased antibody dependent cytotoxicity and increased direct B cell killing compared to rituximab, has shown promise in a Phase 2 study in lupus nephritis (NCT02550652) (14). Conversely, an early study of another humanized anti-CD20 antibody, ocrelizumab, in lupus was terminated early due to a higher than expected rate of infections (15, 16). Whether these second generation anti-CD20 drugs might provide incremental benefit over rituximab in AAV, without increasing acute or long-term toxicity (e.g. hypogammaglobulinaemia, impaired vaccine responses), will require more detailed study.

Accepted Article
The inhibition of B cell cytokines and survival factors is an alternative approach to direct targeting of B cells. B lymphocyte stimulator (BLyS), for example, plays an important role in B cell survival and circulating BLyS levels are higher in patients with AAV than in healthy controls. After treatment with rituximab (in AAV and other autoimmune diseases) serum BLyS levels rise (17, 18), which may herald relapse. In vitro, BlyS is released from neutrophils stimulated with ANCA, suggesting a specific role in AAV (19). Belimumab is an anti-BlyS mAb licensed for treatment of lupus and under investigation in AAV. The Belimumab in Remission of Vasculitis (BREVAS) trial examined the addition of belimumab to azathioprine and glucocorticoids for remission-maintenance, in patients who received either rituximab or cyclophosphamide for induction (20). Regrettably, the trial was terminated early due to under-recruitment and no benefit was observed in the primary endpoint of relapse rate. However, in the subgroup of patients treated with rituximab for induction, fewer relapses were seen with belimumab (0/14 versus 3/13 in placebo group). Although both number of patients and relapses were small, this might suggest potential benefit of belimumab after treatment with rituximab (20). The combination of rituximab and belimumab will be investigated further in the Rituximab and Belimumab Combination Therapy in PR3-AAV trial (COMBIVAS; NCT03967925), in which patients will be treated with rituximab and glucocorticoids for remission-induction, and randomised to receive either belimumab or placebo for one year. It is hypothesized that the addition of belimumab will potentiate the effect of rituximab on B cell depletion and prevent the return of autoreactive cells, or suppress a broader repertoire of B cells (including those not expressing CD20) than rituximab alone, thus inducing more rapid and sustained remission (21).

Bortezomib, a proteasome inhibitor which drives plasma cells with high immunoglobulin synthesis to apoptosis, is an alternative means to target the CD20-ve population. In a mouse model of MPO-AAV, it depleted MPO-specific plasma cells and decreased severity of glomerulonephritis (22). There is a single report of its successful use in a patient with treatment- resistant PR3-AAV (23). The routine use of bortezomib is likely to be limited due to its side effect profile as >30% of patients develop painful peripheral neuropathy, however several novel and potentially less toxic proteasome inhibitors are in development.(24, 25)

Novel cell-based approaches may also be used to target autoreactive B cells. Chimeric antigen receptor T (CAR-T) cells are autologous cells that can be engineered to specifically target

Accepted Article
CD19+ve B cells, an approach has shown efficacy in some haematological malignancies. It is also possible that an extension of this technology – chimeric autoantibody receptor (CAAR) T cell – may target autoreactive B cells through their antigen-specific B cell receptor. CAAR T cells have been tested in a model of pemphigus in humanised mice, where they induced lysis of pathogenic B cells (26). Although in early stages of development, CAAR T cells may provide a curative approach in AAV and other autoimmune diseases where the target autoantigens are defined.

Targeting T cells

The importance of aberrant T cell responses in AAV is increasingly recognised, and studies in experimental models of MPO-AAV have been particularly informative (27). In mice, disease can be attenuated by depletion of either CD4 or CD8 T cells, and adoptive transfer of T cells can initiate glomerular injury independently of ANCA. In patients with AAV, circulating ANCA are predominantly class-switched IgG1 and IgG4, implying T cell help. Immunostaining has identified T cells in the glomeruli and tubulointerstitium in renal biopsy tissue from patients with renal AAV, and several abnormalities of circulating T cell phenotype or function have been reported in patients with active disease (28, 29). An exhausted T cell phenotype has been shown to correlate with disease relapse (30). Activation of circulating T cells is reported to persist in remission despite treatment, and so there may be a particular role for anti-T cell therapies in preventing relapse (31).

There are several small studies using T-cell directed therapies for remission induction, typically in patients with refractory disease. An open label cohort study reported 15 patients with relapsing or refractory disease treated with anti-thymocyte globulin (ATG), in whom 13 showed a favourable response (32). Alemtuzumab is a humanised anti-CD52 mAb which depletes all lymphocytes, with a particularly long-lasting effect on T cells – CD4+ counts take approximately 60 months to recover (33). When CD4+ T cells do eventually repopulate after alemtuzumab, some reports in patients with multiple sclerosis show a skew towards a Treg phenotype, which could contribute to long-lasting immunomodulatory effects (34). Long-term follow up of 71 patients with refractory AAV treated with alemtuzumab showed that 80% achieved remission, although relapse and severe adverse events were common (35). A subsequent Phase 2 RCT, Alemtuzumab for ANCA Associated Refractory Vasculitis (ALEVIATE), compared high- and low-dose alemtuzumab in a

Accepted Article
mixed cohort of patients with refractory AAV or Behcet’s disease. A preliminary report indicates that at six months, 65% had achieved remission and, although relapse was common, 35% had sustained remission at one year, by which point 26% of patients experienced an adverse event (36). Thus, there may be a role for alemtuzumab in the treatment of patients with difficult-to-treat disease, although the potential for adverse events is high compared to standard treatment strategies, likely reflecting both drug toxicity and susceptibility to infection due to disease-related factors. There are also reports autoimmune phenomena occurring after alemtuzumab treatment in other diseases such as multiple sclerosis, thought to be driven by expansion of T cells which have escaped deletion and become chronically activated; whether patients with AAV are at similar risk should also be considered. (37).

In patients with non-severe disease, abatacept, a fusion protein comprised of the Fc region of IgG1 fused to CTLA4 has been tested. Abatacept prevents the co-stimulatory signalling via CD80 and CD86 which is needed for antigen presenting cell activation of T cells (38). An open-label study of 20 patients with relapsing, non-severe GPA who received abatacept in addition to methotrexate, MMF or azathioprine, reported remission rates of 80%, and the ability to wean glucocorticoid in
>70%.(39) A RCT evaluating this approach in a glucocorticoid-free regimen is currently recruiting (ABROGATE; NCT02108860).

The TH17/IL-17/IL-23 axis is also known to play a role in the pathogenesis of AAV. IL-23 and IL- 17 levels are raised in the serum of patients with active disease, and stimulation of neutrophils with ANCA has been shown to induce production of IL-17 (40, 41). In one study, IL-17 deficient mice were protected from developing MPO-AAV (42). Monoclonal antibodies against IL-17 (seikinumab) and IL-23 (ustekinumab) have been tested in psoriasis and rheumatoid arthritis, but there are no reports of their use in AAV to date.

Targeting cytokines

Levels of circulating cytokines such as IL-6 and TNFα are elevated in patients with active AAV (43, 44). A number of open-label studies and case series have reported successful use of anti- TNFα therapies, although these results were not confirmed when tested in RCT, the largest of which – Wegener’s Granulomatosis Etanercept Trial (WGET) – recruited 174 patients with GPA,

Accepted Article
who were randomised to receive either etanercept or placebo, in addition to standard treatment with glucocorticoids and methotrexate or cyclophosphamide, for remission-maintenance (45). There was no benefit from etanercept on sustained remission rates and this negative trial outcome means that anti-TNFα agents have largely been discounted as a potential therapeutic option in AAV, though they may yet have a niche role in the treatment of specific disease manifestations such as ocular inflammation (46).

IL-6 promotes B cell differentiation, activates macrophages, and induces production of other cytokines; serum IL-6 levels are elevated in patients with AAV, and IL-6 is expressed at sites of tissue inflammation (43). There are several case reports of tocilizumab, a humanised anti-IL-6R mAb, in treatment of AAV, with many reporting complete and sustained remission in patients with otherwise refractory disease (43, 47). Others have reported less favourable outcomes, with treatment failure or infectious complications (47). Given the successful use of toclizumab in other systemic autoimmune rheumatic diseases, controlled studies may be warranted to define the role of anti-IL-6 therapy in AAV.

Targeting complement

While historically regarded as a ‘pauci-immune’ vasculitis, with few immunoglobulin or complement deposits in tissue, the past decade has seen the important role of complement in disease pathogenesis come to light (8). In patients, careful examination has identified complement deposition at sites of tissue inflammation in AAV, and altered levels of plasma and urinary complement components have been shown to correlate with disease severity (48, 49). Convincing evidence of complement involvement came from experimental mouse models, where a series of elegant studies dissected a role for alternative pathway activation, and for the receptor of C5a, a potent anaphylatoxin and chemoattractant, in disease pathogenesis. (50). In vitro, C5a can prime neutrophils to respond to ANCA stimulation, and both ANCA-stimulated neutrophils and NETS can activate the alternative complement cascade leading to a positive feedback loop (51, 52). Ultimately it was shown that in mice transgenic for the human C5a receptor, a small molecule antagonist of the C5aR1 (avacopan, CCX168), was an effective treatment for the passive transfer model of MPO-AAV (53).

Accepted Article
This compound then showed promising results in an early phase clinical study, where it was found to be a non-inferior substitute for prednisolone during remission-induction (54). However, this study was small (n=67), of short duration (12 weeks), and included only patients with non-severe disease. A subsequent phase 3 trial of avacopan (ADVOCATE; NCT02994927) completed recruitment of 300 patients in 2018. They were randomised to receive either avacopan or glucocorticoids during remission-induction with either cyclophosphamide or rituximab, and top- line data released in late-2019 suggests non-inferiority of avacopan at 26 weeks and superiority over glucocorticoids at 52 weeks, with an acceptable safety profile. However, full publication of the study is awaited, and it should be highlighted that the most severe cases (those with eGFR<15 ml/min, requiring dialysis or plasma exchange) were still excluded.

An alternative anti-C5a treatment, IFX-1, a mAb targeting C5a rather than C5aR, which may therefore have differing biological effects to avocapan, is also being evaluated in phase 2 studies. Patients will be randomised to standard glucocorticoids, IFX-1 and reduced glucocorticoids, or IFX-1 and no glucocorticoids, during remission-induction (European study, NCT03895801) or to standard of care plus IFX-1 or placebo (North American study, NCT03712345). Recruitment is ongoing and completion is estimated by July 2021. Blockade of C5 cleavage is another potential treatment for AAV, though eculizumab in AAV is limited to case reports (55).

Targeting neutrophils and monocytes

There is extensive evidence for a pathogenic role for neutrophils in AAV. That ANCA bind to and activate neutrophils, causing them to degranulate and produce reactive oxygen species, was first shown nearly 30 years ago (56). ANCA stimulation of neutrophils has also been shown to activate intracellular signalling cascades leading to increased neutrophil adhesion and transmigration at the vascular endothelium (57). ANCA stimulation can induce NETosis, a specialised form of cell death with release of neutrophil extracellular traps (NETs; extra-cellular meshes of decondensed chromatin and granular proteins). NETs are pathogenic in AAV; they can activate dendritic cells, autoreactive B cells, and complement; they are directly injurious to endothelium; and they may play a role in loss of tolerance to ANCA antigens (52, 58). While many studies have focussed on the role of neutrophils, monocytes also express the ANCA autoantigens and respond similarly to

Accepted Article
ANCA stimulation in vitro (59), and thus may contribute to tissue injury. A number of agents that target these neutrophil- and monocyte-mediated functions in AAV are in pre-clinical development.

Inhibiting NETosis may attenuate both vascular damage and potentiation of the autoimmune response by limiting aberrant extracellular expression of ANCA autoantigens. Peptidylarginine deiminase 4 (PAD-4) is essential for NET formation, as it plays a role in citrullination of histones, and PAD-4 inhibition decreases NET formation in vitro (60). In a mouse model of MPO-AAV, PAD-4 deficiency or use of a selective inhibitor decreased NETosis, MPO deposition, glomerular injury, and cell infiltration (61). PAD-4 inhibition has also been tested in mouse models of lupus, but as yet there have been no studies in humans.

Cathepsin C is a lysosomal peptidase which acts in the bone marrow to cleave neutrophil serine proteinases (NSP), including neutrophil elastase and PR3, to their mature, active forms (62). Activated neutrophils release large amounts of these NSP into the extra-cellular space, where they may initiate tissue inflammation and injury as a constituent of NETs. In a mouse model of MPO- AAV, knockout of cathepsin C protected from disease and decreased MPO-ANCA induced IL-1β production in vitro (63). Cleaved NSP may also remain bound to the neutrophil cell surface and, in PR3-AAV, this translocation of PR3 to the cell surface may perpetuate disease; there is evidence in GPA that patients with a higher levels of membrane-bound PR3 have more severe features (64, 65). Thus, reducing cell surface expression of PR3 by preventing its activation by cathepsin C has been suggested as a potential therapeutic. A recently developed pharmacological inhibitor of cathepsin C decreases membrane bound PR3 on neutrophils, with no effect on neutrophil differentiation. When used in vitro, PR3-ANCA-mediated neutrophil activation was diminished and the compound also showed pharmacological activity in mice, although it was not tested in an in vivo model of AAV (66).

Directly targeting MPO, the other ANCA autoantigen, is another approach which has been assessed in animal models. Like PR3, MPO is released from neutrophils and monocytes following activation, and may cause injury and activate autoreactive B and T cells. Extracellular MPO can deposit in glomeruli in AAV, and the amount of deposition correlates with severity of disease (67). In vivo, treatment of mice with an MPO inhibitor decreased severity of crescentic glomerulonephritis (67).

Accepted Article
Spleen tyrosine kinase (Syk) is a cytoplasmic protein tyrosine kinase that is highly expressed in neutrophils and monocytes, where it plays a role in signalling for activatory Fc receptors and some integrins (68). Syk is activated in neutrophils following ANCA stimulation (69), and can be detected in leucocytes within glomerular lesion in patients with ANCA-associated renal disease (70, 71) . Fostamatinib, a small molecule inhibitor with selectivity for Syk, inhibits ANCA- induced neutrophil responses in vitro, and is an effective treatment for a rat model of MPO-AAV (70, 72). Syk is also critical for BCR signalling, and fostamatinib reduced autoantibody responses in experimental anti-GBM disease, suggesting a potential dual therapeutic effect in AAV (73).

There may be concerns that targeting these innate immune responses may leave patients vulnerable to infection, though it is reassuring that congenital deficiencies of Cathespin C and MPO, for example, have relatively mild clinical phenotypes. In addition, clinical studies of Syk inhibition in other diseases, including RA, IgA nephropathy and ITP, did not show a risk of severe infections, supporting future trials of these approaches in AAV.

Combination drug therapy

Drugs targeting the innate immune response may be an effective substitute for glucocorticoids during acute disease, though they may be less effective for suppressing the underlying adaptive response, which is needed to secure long-term remission. Conversely, specific targeting of B and T lymphocytes may not provide sufficiently rapid responses during acute flares to prevent accrual of organ damage. As an increasing number of potential therapeutic agents are identified, future studies will need to address how they are best used in sequence or in combination, with each other or with existing therapies, and during different phases of disease, to improve outcomes and reduce toxicity. The negative results in some RCT in AAV, such as those with etanercept in the WGET study, may relate to their use as ‘add on’ therapy to conventional treatment, such that potential signals of biological activity were lost; whereas the recent enthusiasm for complement inhibition arose following a successful trial designed to demonstrate that avacapan could wholly replace glucocortoids during remission induction

Accepted Article
Conversely, ‘multi-target’ therapy has recently emerged as an effective approach in lupus nephritis, and combination approaches that target multiple aspects of the immune and inflammatory response may likewise be an effective way to provide rapid and sustained disease control in AAV, while avoiding toxicities caused by excessive exposure to individual drugs. One such combination approach using low-dose intravenous cyclophosphamide and rituximab, along with a rapid oral glucocorticoid taper, has been described in an open-label cohort study. Rates of remission at six months, mortality, long-term relapse rates and renal outcomes were favourable when compared to matched historical controls from EUVAS studies(74) (75). A similar approach, using a short course of oral cyclophosphamide and rituximab, has been reported in a single centre retrospective case series of 129 patients, again showing favourable rates of remission-induction and relapse (76). It is suggested that the early combination of cyclophosphamide and rituximab may allow reduction in glucocorticoid-exposure during acute disease, while inducing sustained remission, perhaps through potentiation of B cell depletion.
However, concern for increased toxicity remains. A clinical trial of this combination treatment regimen - Exploring Durable Remission With Rituximab in Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis (ENDURRANCE; NCT03942887) - is currently recruiting, and will assess both immunological responses (as its primary outcome) and clinical outcomes (including adverse events) following combination induction treatment with rituximab, low-dose intravenous cyclophosphamide, and low-dose glucocorticoids.

Conclusions

Modern immunosuppression regimens have transformed outcomes in AAV, and several evidence- based treatment guidelines are now available, informed by the findings of high quality RCTs There are, however, unmet needs relating to drug side effects and the unpredictable nature of disease relapse. Advances in understanding of disease pathogenesis have identified many potential new targets for therapy, directed to various aspects of adaptive and innate immune responses that underlie AAV, which may tackle some of these issues. Some have already progressed to clinical studies, such as targeting of the alternative complement cascade, and others remain in the pre- clinical stages of development. Future clinical trials of these novel therapeutics will need to establish their efficacy and, as an increasing number of potential treatments becomes available, indicate how they can used to complement or replace existing approaches. With more agents at our

Accepted Article
disposal, future studies may also need to incorporate the use of biomarkers and predictors of flare, and stratification for patient factors that may influence treatment response, including age, co- morbidities, pattern of organ involvement, including the presence of granulomatous lesions, ANCA serotype, and potentially genotype, so that subgroups of patients likely to benefit from a given therapy can be identified. This should allow for the development of more tailored treatment protocols that maximise response, while minimising side effects from unnecessary drug exposure, and thus improved outcomes for patients with AAV.

Accepted Article
Figure 1: Current concepts in disease pathogenesis in ANCA-associated vasculitis (AAV) and potential therapeutic targets.
Cytokine or C5a priming of neutrophils leads to expression of ANCA antigens at the cell surface. ANCA can then activate neutrophils to produce reactive oxygen species (ROS) or to undergo NETosis, leading to endothelial cell injury. Activation of the alternative complement cascade leads to a positive feedback loop of neutrophil priming and activation. Dysregulated B and T cell responses may contribute to both the initial generation of autoimmunity and to the potentiation of inflammation. Potential new therapeutics are indicated, including targeting of B cells with second generation anti-CD20 or anti-BLyS agents; targeting of T cells or their activation by antigen presenting cells (ATG, alemtuzumab, abatacept); targeting complement with anti-C5a agents; targeting cytokines such as IL-6 or TNFα; and target neutrophils and/or monocytes with MPO, PAD-4, or Syk inhibition.

Accepted Article

Table 1. Selected Recent and Ongoing trials of novel treatments in ANCA-associated vasculitis (AAV).
Study (NCT) Design (n) Key Inclusion criteria Primary end point Status (May
2020) Results & Comments
Targeting B cells
COMBIVAS: Double blind RCT of Active PR3-AAV, Time to PR3-ANCA Recruiting An experimental medicine study that will assess
Rituximab and belimumab or placebo eGFR>30 ml/min negativity whether dual B cell immunotherapy will improve
Belimumab (in addition to RTX & biological end-points, including ANCA titre and B
Combination Therapy glucocorticoids) for cell number and phenotype in both circulating
in PR3-AAV remission induction and lymph node compartments.
(NCT03967925) (Target n= 30) Estimated completion Feb 2022.

ENDURRANCE:
Open label parallel RCT
Active MPA/GPA
ANCA negativity at 24 weeks
Recruiting
A mechanistic study that will assess
Exploring Durable of RTX & low dose CYC vs immunological responses after addition of
Remission with RTX (in addition to cyclophosphamide to rituximab, using high-
Rituximab in ANCA- glucocorticoids) for sensitivity analysis of circulating B cells and
Associated Vasculitis remission induction plasma cell populations.
(NCT03942887) (Target n= 47) Estimated completion April 2023.

Accepted Article

Targeting T cells
ALEVIATE: Randomised, prospective Refractory AAV or Response at 6 months, Complete Results presented in abstract form in 201936:
Alemtuzumab for open-label study of high Behcets with failure to SAE at 6 months ⦁ 65% in remission at 6 months
ANCA Associated dose vs low dose respond to ⦁ 35% with sustained remission
Refractory Vasculitis alemtuzumab for conventional ⦁ SAE in 26% of patients
(NCT01405807) remission induction treatment
(n=23; 12 AAV)

ABROGATE:
Double blind RCT of
Relapsing non-severe
Treatment failure rate
Recruiting
A Phase 3 study that will evaluate the efficacy of
Abatacept for the abatacept vs placebo (in GPA (relapse, disease worsening, abatacept to achieve sustained glucocorticoid-
Treatment of addition to SOC) for or BVAS>1 at 6 months) free remission in non-severe GPA.
Relapsing Non-Severe maintenance of Estimated completion Sept 2024
GPA remission.
(NCT02108860) (Target n= 66)
Targeting Complement

Accepted Article

ANCA, anti-neutrophil cytoplasm antibody; BVAS, Birmingham vasculitis activity score; CYC, cyclophosphamide; eGFR, estimated glomerular filtration rate; GPA, granulomatosis with polyangiitis; MPA, microscopic polyangiitis; PR3, proteinase 3; RCT, randomised control trial; RTX, rituximab; SAE, serious adverse event; SOC, standard of care.

Accepted Article
References
⦁ Jennette JC, Falk RJ, Bacon PA, Basu N, Cid MC, Ferrario F, et al. 2012 revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides. Arthritis and rheumatism. 2013;65(1):1- 11.
⦁ FAUCI AS, HAYNES BF, KATZ P, WOLFF SM. Wegener’s Granulomatosis: Prospective Clinical and Therapeutic Experience With 85 Patients for 21 Years. Annals of internal medicine. 1983;98(1):76-85.
⦁ Rhee RL, Hogan SL, Poulton CJ, McGregor JA, Landis JR, Falk RJ, et al. Trends in Long-Term Outcomes Among Patients With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis With Renal Disease. Arthritis & rheumatology (Hoboken, NJ). 2016;68(7):1711-20.
⦁ Geetha D, Jin Q, Scott J, Hruskova Z, Hanouneh M, Little MA, et al. Comparisons of Guidelines and Recommendations on Managing Antineutrophil Cytoplasmic Antibody–Associated Vasculitis. Kidney International Reports. 2018;3(5):1039-49.
⦁ Flossmann O, Berden A, de Groot K, Hagen C, Harper L, Heijl C, et al. Long-term patient survival in ANCA-associated vasculitis. Annals of the rheumatic diseases. 2011;70(3):488.
⦁ Little MA, Nightingale P, Verburgh CA, Hauser T, De Groot K, Savage C, et al. Early mortality in systemic vasculitis: relative contribution of adverse events and active vasculitis. Annals of the rheumatic diseases. 2010;69(6):1036-43.
⦁ Prendecki M, Pusey CD. Recent advances in understanding of the pathogenesis of ANCA- associated vasculitis. F1000Research. 2018;7.
⦁ Chen M, Jayne DRW, Zhao MH. Complement in ANCA-associated vasculitis: mechanisms and implications for management. Nature reviews Nephrology. 2017;13(6):359-67.
⦁ McClure M, Gopaluni S, Jayne D, Jones R. B cell therapy in ANCA-associated vasculitis: current and emerging treatment options. Nature reviews Rheumatology. 2018;14(10):580-91.
⦁ Martinez Valenzuela L, Bordignon Draibe J, Fulladosa Oliveras X, Bestard Matamoros O, Cruzado Garrit JM, Torras Ambrós J. T-lymphocyte in ANCA-associated vasculitis: what do we know? A pathophysiological and therapeutic approach. Clinical kidney journal. 2019;12(4):503-11.
⦁ Jones RB, Cohen Tervaert JW, Hauser T, Luqmani R, Morgan MD, Peh CA, et al. Rituximab versus Cyclophosphamide in ANCA-Associated Renal Vasculitis. New England Journal of Medicine. 2010;363(3):211-20.
⦁ Alberici F, Smith RM, Jones RB, Roberts DM, Willcocks LC, Chaudhry A, et al. Long-term follow-up of patients who received repeat-dose rituximab as maintenance therapy for ANCA-associated vasculitis. Rheumatology (Oxford, England). 2015;54(7):1153-60.

⦁ Accepted Article
⦁ McAdoo SP, Bedi R, Tarzi R, Griffith M, Pusey CD, Cairns TD. Ofatumumab for B cell depletion therapy in ANCA-associated vasculitis: a single-centre case series. Rheumatology (Oxford, England). 2016;55(8):1437-42.
⦁ Reddy V, Klein C, Isenberg DA, Glennie MJ, Cambridge G, Cragg MS, et al. Obinutuzumab induces superior B-cell cytotoxicity to rituximab in rheumatoid arthritis and systemic lupus erythematosus patient samples. Rheumatology (Oxford, England). 2017;56(7):1227-37.
⦁ Mössner E, Brünker P, Moser S, Püntener U, Schmidt C, Herter S, et al. Increasing the efficacy of CD20 antibody therapy through the engineering of a new type II anti-CD20 antibody with enhanced direct and immune effector cell–mediated B-cell cytotoxicity. Blood. 2010;115(22):4393-402.
⦁ Mysler EF, Spindler AJ, Guzman R, Bijl M, Jayne D, Furie RA, et al. Efficacy and safety of ocrelizumab in active proliferative lupus nephritis: results from a randomized, double-blind, phase III study. Arthritis and rheumatism. 2013;65(9):2368-79.
⦁ Pollard RP, Abdulahad WH, Vissink A, Hamza N, Burgerhof JG, Meijer JM, et al. Serum levels of BAFF, but not APRIL, are increased after rituximab treatment in patients with primary Sjogren’s syndrome: data from a placebo-controlled clinical trial. Annals of the rheumatic diseases. 2013;72(1):146-8.
⦁ Krumbholz M, Specks U, Wick M, Kalled SL, Jenne D, Meinl E. BAFF is elevated in serum of patients with Wegener’s granulomatosis. Journal of autoimmunity. 2005;25(4):298-302.
⦁ Holden NJ, Williams JM, Morgan MD, Challa A, Gordon J, Pepper RJ, et al. ANCA-stimulated neutrophils release BLyS and promote B cell survival: a clinically relevant cellular process. Annals of the rheumatic diseases. 2011;70(12):2229-33.
⦁ Jayne D, Blockmans D, Luqmani R, Moiseev S, Ji B, Green Y, et al. Efficacy and Safety of Belimumab and Azathioprine for Maintenance of Remission in Antineutrophil Cytoplasmic Antibody- Associated Vasculitis: A Randomized Controlled Study. Arthritis & rheumatology. 2019;71(6):952-63.
⦁ McClure M, Gopaluni S, Wason J, Rosen AN, Henderson R, Salama A, et al. 322. A RANDOMISED, DOUBLE-BLIND, CONTROLLED, MECHANISTIC STUDY OF RITUXIMAB AND BELIMUMAB COMBINATION THERAPY IN PR3 ANCA-ASSOCIATED VASCULITIS (COMBIVAS): STUDY PROTOCOL. Rheumatology. 2019;58(Supplement_2).
⦁ Bontscho J, Schreiber A, Manz RA, Schneider W, Luft FC, Kettritz R. Myeloperoxidase-specific plasma cell depletion by bortezomib protects from anti-neutrophil cytoplasmic autoantibodies-induced glomerulonephritis. Journal of the American Society of Nephrology : JASN. 2011;22(2):336-48.
⦁ Novikov P, Moiseev S, Bulanov N, Shchegoleva E. Bortezomib in refractory ANCA-associated vasculitis: a new option? Annals of the rheumatic diseases. 2016;75(1):e9-e.
⦁ Badros A, Goloubeva O, Dalal JS, Can I, Thompson J, Rapoport AP, et al. Neurotoxicity of bortezomib therapy in multiple myeloma: a single-center experience and review of the literature. Cancer. 2007;110(5):1042-9.

⦁ Accepted Article
⦁ Hiepe F, Radbruch A. Plasma cells as an innovative target in autoimmune disease with renal manifestations. Nature Reviews Nephrology. 2016;12(4):232-40.
⦁ Ellebrecht CT, Bhoj VG, Nace A, Choi EJ, Mao X, Cho MJ, et al. Reengineering chimeric antigen receptor T cells for targeted therapy of autoimmune disease. Science. 2016;353(6295):179-84.
⦁ Shochet L, Holdsworth S, Kitching AR. Animal Models of ANCA Associated Vasculitis. Frontiers in immunology. 2020;11:525.
⦁ Geetha D, Sethi S, De Vriese AS, Specks U, Kallenberg CGM, Lim N, et al. Interstitial Immunostaining and Renal Outcomes in Antineutrophil Cytoplasmic Antibody-Associated Glomerulonephritis. American journal of nephrology. 2017;46(3):231-8.
⦁ Marinaki S, Kalsch AI, Grimminger P, Breedijk A, Birck R, Schmitt WH, et al. Persistent T-cell activation and clinical correlations in patients with ANCA-associated systemic vasculitis. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association – European Renal Association. 2006;21(7):1825-32.
⦁ McKinney EF, Lee JC, Jayne DR, Lyons PA, Smith KG. T-cell exhaustion, co-stimulation and clinical outcome in autoimmunity and infection. Nature. 2015;523(7562):612-6.
⦁ Sanders JS, Huitma MG, Kallenberg CG, Stegeman CA. Plasma levels of soluble interleukin 2 receptor, soluble CD30, interleukin 10 and B cell activator of the tumour necrosis factor family during follow-up in vasculitis associated with proteinase 3-antineutrophil cytoplasmic antibodies: associations with disease activity and relapse. Annals of the rheumatic diseases. 2006;65(11):1484-9.
⦁ Schmitt WH, Hagen EC, Neumann I, Nowack R, Flores-Suarez LF, van der Woude FJ. Treatment of refractory Wegener’s granulomatosis with antithymocyte globulin (ATG): an open study in 15 patients. Kidney Int. 2004;65(4):1440-8.
⦁ Coles AJ, Cox A, Le Page E, Jones J, Trip SA, Deans J, et al. The window of therapeutic opportunity in multiple sclerosis: evidence from monoclonal antibody therapy. Journal of neurology. 2006;253(1):98-108.
⦁ Haas J, Wurthwein C, Korporal-Kuhnke M, Viehoever A, Jarius S, Ruck T, et al. Alemtuzumab in Multiple Sclerosis: Short- and Long-Term Effects of Immunodepletion on the Peripheral Treg Compartment. Frontiers in immunology. 2019;10:1204.
⦁ Walsh M, Chaudhry A, Jayne D. Long-term follow-up of relapsing/refractory anti-neutrophil cytoplasm antibody associated vasculitis treated with the lymphocyte depleting antibody alemtuzumab (CAMPATH-1H). Annals of the rheumatic diseases. 2008;67(9):1322-7.
⦁ Gopaluni S, Goymer D, McClure M, Cahill H, Broadhurst E, Smith R, et al. 302.  ALEMTUZUMAB FOR RELAPSING AND REFRACTORY PRIMARY SYSTEMIC VASCULITIS – A TRIAL OF EFFICACY AND SAFETY (ALEVIATE): A RANDOMISED OPEN-LABEL PHASE II CLINICAL TRIAL. Rheumatology. 2019;58(Supplement_2).

⦁ Accepted Article
⦁ Jones JL, Thompson SA, Loh P, Davies JL, Tuohy OC, Curry AJ, et al. Human autoimmunity after lymphocyte depletion is caused by homeostatic T-cell proliferation. Proc Natl Acad Sci U S A. 2013;110(50):20200-5.
⦁ Bonelli M, Scheinecker C. How does abatacept really work in rheumatoid arthritis? Current opinion in rheumatology. 2018;30(3):295-300.
⦁ Langford CA, Monach PA, Specks U, Seo P, Cuthbertson D, McAlear CA, et al. An open-label trial of abatacept (CTLA4-IG) in non-severe relapsing granulomatosis with polyangiitis (Wegener’s). Annals of the rheumatic diseases. 2014;73(7):1376-9.
⦁ Nogueira E, Hamour S, Sawant D, Henderson S, Mansfield N, Chavele KM, et al. Serum IL-17 and IL-23 levels and autoantigen-specific Th17 cells are elevated in patients with ANCA-associated vasculitis. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association – European Renal Association. 2010;25(7):2209-17.
⦁ Hoshino A, Nagao T, Nagi-Miura N, Ohno N, Yasuhara M, Yamamoto K, et al. MPO-ANCA induces IL-17 production by activated neutrophils in vitro via classical complement pathway-dependent manner. Journal of autoimmunity. 2008;31(1):79-89.
⦁ Gan PY, Steinmetz OM, Tan DS, O’Sullivan KM, Ooi JD, Iwakura Y, et al. Th17 cells promote autoimmune anti-myeloperoxidase glomerulonephritis. Journal of the American Society of Nephrology : JASN. 2010;21(6):925-31.
⦁ Berti A, Cavalli G, Campochiaro C, Guglielmi B, Baldissera E, Cappio S, et al. Interleukin-6 in ANCA-associated vasculitis: Rationale for successful treatment with tocilizumab. Seminars in arthritis and rheumatism. 2015;45(1):48-54.
⦁ Ohlsson S, Wieslander J, Segelmark M. Circulating cytokine profile in anti-neutrophilic cytoplasmatic autoantibody-associated vasculitis: prediction of outcome? Mediators of inflammation. 2004;13(4):275-83.
⦁ Etanercept plus standard therapy for Wegener’s granulomatosis. The New England journal of medicine. 2005;352(4):351-61.
⦁ Levy-Clarke G, Jabs DA, Read RW, Rosenbaum JT, Vitale A, Van Gelder RN. Expert panel recommendations for the use of anti-tumor necrosis factor biologic agents in patients with ocular inflammatory disorders. Ophthalmology. 2014;121(3):785-96.e3.
⦁ Sakai R, Kondo T, Kurasawa T, Nishi E, Okuyama A, Chino K, et al. Current clinical evidence of tocilizumab for the treatment of ANCA-associated vasculitis: a prospective case series for microscopic polyangiitis in a combination with corticosteroids and literature review. Clinical Rheumatology. 2017;36(10):2383-92.

⦁ Accepted Article
⦁ Xing GQ, Chen M, Liu G, Heeringa P, Zhang JJ, Zheng X, et al. Complement activation is involved in renal damage in human antineutrophil cytoplasmic autoantibody associated pauci-immune vasculitis. Journal of clinical immunology. 2009;29(3):282-91.
⦁ Gou SJ, Yuan J, Wang C, Zhao MH, Chen M. Alternative complement pathway activation products in urine and kidneys of patients with ANCA-associated GN. Clinical journal of the American Society of Nephrology : CJASN. 2013;8(11):1884-91.
⦁ Xiao H, Schreiber A, Heeringa P, Falk RJ, Jennette JC. Alternative complement pathway in the pathogenesis of disease mediated by anti-neutrophil cytoplasmic autoantibodies. The American journal of pathology. 2007;170(1):52-64.
⦁ Schreiber A, Xiao H, Jennette JC, Schneider W, Luft FC, Kettritz R. C5a receptor mediates neutrophil activation and ANCA-induced glomerulonephritis. Journal of the American Society of Nephrology : JASN. 2009;20(2):289-98.
⦁ Wang H, Wang C, Zhao MH, Chen M. Neutrophil extracellular traps can activate alternative complement pathways. Clinical and experimental immunology. 2015;181(3):518-27.
⦁ Xiao H, Dairaghi DJ, Powers JP, Ertl LS, Baumgart T, Wang Y, et al. C5a receptor (CD88) blockade protects against MPO-ANCA GN. Journal of the American Society of Nephrology : JASN. 2014;25(2):225-31.
⦁ Jayne DRW, Bruchfeld AN, Harper L, Schaier M, Venning MC, Hamilton P, et al. Randomized Trial of C5a Receptor Inhibitor Avacopan in ANCA-Associated Vasculitis. Journal of the American Society of Nephrology : JASN. 2017;28(9):2756-67.
⦁ Ribes D, Belliere J, Piedrafita A, Faguer S. Glucocorticoid-free induction regimen in severe ANCA-associated vasculitis using a combination of rituximab and eculizumab. Rheumatology. 2019.
⦁ Falk RJ, Terrell RS, Charles LA, Jennette JC. Anti-neutrophil cytoplasmic autoantibodies induce neutrophils to degranulate and produce oxygen radicals in vitro. Proc Natl Acad Sci U S A. 1990;87(11):4115-9.
⦁ Radford DJ, Luu NT, Hewins P, Nash GB, Savage CO. Antineutrophil cytoplasmic antibodies stabilize adhesion and promote migration of flowing neutrophils on endothelial cells. Arthritis and rheumatism. 2001;44(12):2851-61.
⦁ Sangaletti S, Tripodo C, Chiodoni C, Guarnotta C, Cappetti B, Casalini P, et al. Neutrophil extracellular traps mediate transfer of cytoplasmic neutrophil antigens to myeloid dendritic cells toward ANCA induction and associated autoimmunity. Blood. 2012;120(15):3007-18.
⦁ Jennette JC, Falk RJ. ANCAs are also antimonocyte cytoplasmic autoantibodies. Clinical journal of the American Society of Nephrology : CJASN. 2015;10(1):4-6.
⦁ Lewis HD, Liddle J, Coote JE, Atkinson SJ, Barker MD, Bax BD, et al. Inhibition of PAD4 activity is sufficient to disrupt mouse and human NET formation. Nature Chemical Biology. 2015;11:189.

⦁ Accepted Article
⦁ O’Sullivan KM, Lo CY, Summers SA, Elgass KD, McMillan PJ, Longano A, et al. Renal participation of myeloperoxidase in antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis. Kidney Int. 2015;88(5):1030-46.
⦁ Seren S, Rashed Abouzaid M, Eulenberg-Gustavus C, Hirschfeld J, Nasr Soliman H, Jerke U, et al. Consequences of cathepsin C inactivation for membrane exposure of proteinase 3, the target antigen in autoimmune vasculitis. J Biol Chem. 2018;293(32):12415-28.
⦁ Schreiber A, Pham CT, Hu Y, Schneider W, Luft FC, Kettritz R. Neutrophil serine proteases promote IL-1beta generation and injury in necrotizing crescentic glomerulonephritis. Journal of the American Society of Nephrology : JASN. 2012;23(3):470-82.
⦁ Korkmaz B, Lesner A, Letast S, Mahdi YK, Jourdan M-L, Dallet-Choisy S, et al. Neutrophil proteinase 3 and dipeptidyl peptidase I (cathepsin C) as pharmacological targets in granulomatosis with polyangiitis (Wegener granulomatosis). Seminars in Immunopathology. 2013;35(4):411-21.
⦁ von Vietinghoff S, Schreiber A, Otto B, Choi M, Gobel U, Kettritz R. Membrane proteinase 3 and Wegener’s granulomatosis. Clinical nephrology. 2005;64(6):453-9.
⦁ Jerke U, Eulenberg-Gustavus C, Rousselle A, Kreideweiss S, Grundl M, Eickholz P, et al. 196.  CHARACTERIZATION OF CATHEPSIN C AS A TREATMENT TARGET IN ANCA-ASSOCIATED VASCULITIS. Rheumatology. 2019;58(Supplement_2).
⦁ Antonelou M, Michaelsson E, Evans RDR, Wang CJ, Henderson SR, Walker LSK, et al. Therapeutic Myeloperoxidase Inhibition Attenuates Neutrophil Activation, ANCA-Mediated Endothelial Damage, and Crescentic GN. Journal of the American Society of Nephrology : JASN. 2020;31(2):350-64.
⦁ Mocsai A, Ruland J, Tybulewicz VL. The SYK tyrosine kinase: a crucial player in diverse biological functions. Nature reviews Immunology. 2010;10(6):387-402.
⦁ Hewins P, Williams JM, Wakelam MJO, Savage COS. Activation of Syk in Neutrophils by Antineutrophil Cytoplasm Antibodies Occurs via Fcγ Receptors and CD18. Journal of the American Society of Nephrology. 2004;15(3):796-808.
⦁ McAdoo SP, Prendecki M, Tanna A, Bhatt T, Bhangal G, McDaid J, et al. Spleen tyrosine kinase inhibition is an effective treatment for established vasculitis in a pre-clinical model. Kidney International.
⦁ McAdoo SP, Bhangal G, Page T, Cook HT, Pusey CD, Tam FWK. Correlation of disease activity in proliferative glomerulonephritis with glomerular spleen tyrosine kinase expression. Kidney international. 2015;88(1):52-60.
⦁ Prendecki M, Bhatt T, Gulati K, Dudhiya F, Masuda E, Tam F, et al. 213. LEUCOCYTE SPLEEN TYROSINE KINASE IN ANCA-ASSOCIATED VASCULITIS. Rheumatology. 2019;58(Supplement_2).

⦁ Accepted Article
⦁ McAdoo SP, Reynolds J, Bhangal G, Smith J, McDaid JP, Tanna A, et al. Spleen Tyrosine Kinase Inhibition Attenuates Autoantibody Production and Reverses Experimental Autoimmune GN. Journal of the American Society of Nephrology : JASN. 2014;25(10):2291-302.
⦁ Pepper RJ, McAdoo SP, Moran SM, Kelly D, Scott J, Hamour S, et al. A novel glucocorticoid-free maintenance regimen for anti-neutrophil cytoplasm antibody–associated vasculitis. Rheumatology. 2018;58(2):260-8.
⦁ McAdoo SP, Medjeral-Thomas N, Gopaluni S, Tanna A, Mansfield N, Galliford J, et al. Long-term follow-up of a combined rituximab and cyclophosphamide regimen in renal anti-neutrophil cytoplasm antibody-associated vasculitis. Nephrology Dialysis Transplantation. 2018:gfx378-gfx.
⦁ Cortazar FB, Muhsin SA, Pendergraft WF, 3rd, Wallace ZS, Dunbar C, Laliberte K, et al. Combination Therapy With Rituximab and Cyclophosphamide for Remission Induction in ANCA Vasculitis. Kidney Int Rep. 2018;3(2):394-402.