Complement inhibitors in pediatric kidney diseases: new therapeutic opportunities

Historically, the complement system (classical, lectin, alternative, and terminal pathways) is known to play a crucial role in the etiopathogenesis of many kidney diseases. Direct or indirect activation in these settings is revealed by consumption of complement proteins at the serum level and kidney tissue deposition seen by immunofluorescence and electron microscopy. The advent of eculizumab has shown that complement inhibitors may improve the natural history of certain kidney diseases. Since then, the number of available therapeutic molecules and experimental studies on complement inhibition has increased exponentially. In our narrative review, we give a summary of the main complement inhibitors that have completed phase II and phase III studies or are currently used in adult and pediatric nephrology. The relevant full-text works, abstracts, and ongoing trials (clinicaltrials.gov site) are discussed. Data and key clinical features are reported for eculizumab, ravulizumab, crovalimab, avacopan, danicopan, iptacopan, pegcetacoplan, and narsoplimab. Many of these molecules have been shown to be effective in reducing proteinuria and stabilizing kidney function in different complement-mediated kidney diseases. Thanks to their efficacy and target specificity, these novel drugs may radically improve the outcome of complement-mediated kidney diseases, contributing to an improvement in our understanding of their underlying pathophysiology.

A case of rapid avacopan-induced liver injury in pediatric granulomatosis with polyangiitis

Children with anti-neutrophil cytoplasmic antibody-associated vasculitis benefit immensely from avacopan as it reduces the requirement for steroids. However, descriptions of adverse drug reactions in children are lacking, and the dosage and follow-up intervals are unclear. A 10-year-old boy with initial granulomatosis and polyangiitis presented with diffuse pulmonary hemorrhage. Rituximab and 30 mg avacopan were administered twice daily as induction therapy following methylprednisolone pulse therapy. However, sudden liver function test abnormalities were observed on day 31 of avacopan treatment, despite liver enzyme levels being within the normal range 5 days earlier. A drug-induced lymphocyte stimulation and various infectious disease tests yielded negative results. Discontinuation of rituximab and avacopan resulted in improved liver function; no change in the Birmingham Vasculitis Activity Score during liver function test abnormalities was observed. Avacopan-associated abnormalities in liver function tests suggest that drug-induced liver injury may occur rapidly in children, and appropriate dosing strategies should be reconsidered.

Improved Hearing Impairment of Granulomatosis with Polyangiitis Treated with Rituximab and Avacopan without Glucocorticoids

A 78-year-old woman with a history of intractable otitis media presented with a fever, hearing impairment, thigh pain, and a skin rash. She had renal dysfunction, positive myeloperoxidase-antineutrophil cytoplasmic autoantibody, otitis media, and multiple nodules in both lungs. She was diagnosed with granulomatosis with polyangiitis, crescentic glomerulonephritis, and interstitial nephritis, which was confirmed in a kidney biopsy specimen. Induction therapy with rituximab and avacopan without glucocorticoids promptly resolved her fever and thigh pain and improved her auditory acuity and nodule in the right lung. The patient experienced no adverse effects with rituximab or avacopan.

A projected cost-utility analysis of avacopan for the treatment of antineutrophil cytoplasmic antibody-associated vasculitis in Spain

BACKGROUND

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) are rare autoimmune diseases characterized by inflammation of blood vessels. This study aimed to assess the cost-utility of avacopan in combination with rituximab (RTX) or cyclophosphamide (CYC) compared with glucocorticoids (GC) for the treatment of severe, active AAV in Spain.

METHODS

A 9-state Markov model was designed to reflect the induction of remission and sustained remission of AAV over a lifetime horizon. Clinical data and utility values were mainly obtained from the ADVOCATE trial, and costs (€ 2022) were sourced from national databases. Quality-adjusted life years (QALYs), and incremental cost-utility ratio (ICUR) were evaluated. An annual discount rate of 3% was applied. Sensitivity analyses were performed to examine the robustness of the results.

RESULTS

Avacopan yielded an increase in effectiveness (6.52 vs. 6.17 QALYs) and costs (€16,009) compared to GC, resulting in an ICUR of €45,638 per additional QALY gained. Avacopan was associated with a lower incidence of end-stage renal disease (ESRD), relapse and hospitalization-related adverse events. Sensitivity analyses suggested that the model outputs were robust and that the progression to ESRD was a driver of ICUR.

CONCLUSIONS

Avacopan is a cost-effective option for patients with severe, active AAV compared to GC in Spain.

Successful treatment with avacopan (CCX168) in a pediatric patient with C3 glomerulonephritis

BACKGROUND

C3 glomerulonephritis (C3GN) is a subtype of C3 glomerulopathy (C3G), characterized by dysregulation of the alternative pathway of complement and by dominant C3 by immunofluorescence on the kidney biopsy. There is no approved treatment for patients with C3G. Immunosuppressive drugs as well as biologics have been used with limited success. In recent decades, substantial advances in the understanding of the complement system have led to the development of new complement inhibitors. Avacopan (CCX168) is an orally administered small-molecule C5aR antagonist that blocks the effects of C5a, one of the most potent pro-inflammatory mediators of the complement system.

CASE REPORT

We describe a child with biopsy-proven C3GN treated with avacopan. She was enrolled in the ACCOLADE double-blind placebo-controlled Phase 2 study (NCT03301467), where during the first 26 weeks she was randomized to receive an avacopan-matching placebo orally twice daily, while in the following 26 weeks, the study was open-label and she received avacopan. After a wash-out period, she was restarted on avacopan through an expanded access program.

CONCLUSIONS

In this case, use of avacopan in a pediatric patient with C3GN was safe and well tolerated. On avacopan, the patient was able to discontinue mycophenolate mofetil (MMF) while maintaining remission.

Avacopan for the Treatment of Anti-Neutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis

OBJECTIVE

To review the safety and efficacy of avacopan for the treatment of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis.

DATA SOURCES

A systematic review of the literature was performed using the terms avacopan OR tavneos OR CCX168 OR ANCA-associated vasculitis in PubMed and Google Scholar. Articles between January 2016 and January 2023 were considered for inclusion. Bibliographies and ClinicalTrials.gov were also searched for completion.

STUDY SELECTION AND DATA EXTRACTION

Relative English language and human studies related to pharmacology, clinical trials, and safety were included.

DATA SYNTHESIS

The 52-week ADVOCATE and 12-week CLEAR clinical trials evaluated the safety and efficacy of avacopan. The remission rate was 65.7% and 54.9% in the avacopan and placebo group, respectively, in the ADVOCATE trial. The Birmingham Vasculitis Activity Score improved by ≥50% in 86.4% of avacopan treated patients and 70% of prednisone treated patients in the CLEAR trial.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE IN COMPARISON WITH EXISTING DRUGS

Glucocorticoids in combination with cyclophosphamide, azathioprine, and/or rituximab have been a mainstay of ANCA-associated vasculitis treatment. However, short- and long-term medication-related adverse effects risk negative outcomes for patients. Avacopan may provide equivalent to better treatment with fewer side effects due to a reduction, if not elimination, of glucocorticoids.

CONCLUSIONS

Avacopan used in isolation or combination is safe and effective for ANCA-associated vasculitis.

Renal improvement and remission in a patient with refractory ANCA-associated vasculitis treated with avacopan

Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis is associated with end-organ damage resulting in significant morbidity and mortality. Most recently, avacopan, an orally administered selective antagonist of the C5a receptor, was approved by the US Food and Drug Administration as an adjunctive treatment of adult patients with severe, active ANCA-associated vasculitis (granulomatosis with polyangiitis and microscopic polyangiitis) in combination with standard therapy including glucocorticoids. This case study describes a 58-year-old Asian female with severe ANCA-associated vasculitis and acute renal failure who responded to adjunctive therapy with avacopan despite being refractory to rituximab and glucocorticoid therapy.

[Diagnosis and therapy of granulomatosis with polyangiitis and microscopic polyangiitis-2023: consensus of the Austrian society of nephrology (ÖGN) and Austrian society of rheumatology (ÖGR)]

ANCA-associated vasculitides (AAV) are rare, complex systemic diseases that are often difficult to diagnose, because of unspecific clinical symptoms at presentation. However, the clinical course may be very dramatic and even life-threatening, necessitating prompt diagnosis and treatment.Therefore, it is important to increase disease awareness among physicians and support colleagues who are not confronted with these rare diseases on a regular basis. Here, the Austrian Society of Nephrology (ÖGN) and the Austrian Society of Rheumatology (ÖGR) provide a joint consensus on how to best diagnose and manage patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).

Gradual Increase of Avacopan Dose with Concomitant Ursodeoxycholic Acid Use May Help Avoid the Risk of C5a Receptor Inhibitor-induced Liver Injury in Antineutrophil Cytoplasmic Antibody-associated Vasculitis

Microscopic polyangiitis (MPA) is a necrotizing vasculitis characterized by anti-neutrophil cytoplasmic antibody against myeloperoxidase. The C5 receptor inhibitor avacopan effectively sustains remission in MPA with a reduction in prednisolone dosage. Liver damage is a safety concern for this drug. However, when it occurs and how to treat it remains unknown. A 75-year-old man developed MPA and presented with hearing impairment and proteinuria. Methylprednisolone pulse therapy followed by 30 mg/day prednisolone and two doses of weekly rituximab were administered. Avacopan was initiated to taper prednisolone for sustained remission. After nine weeks, liver dysfunction and sparse skin eruptions developed. Cessation of avacopan and initiation of ursodeoxycholic acid (UDCA) improved liver function without discontinuation of prednisolone and other concomitant drugs. After three weeks, avacopan was rechallenged with a small dose which was gradual increased; UDCA was continued. Full-dose avacopan did not induce recurrence of liver injury. Therefore, gradually increasing the dose of avacopan with concomitant UDCA use may help avoid possible avacopan-induced liver injury.

Steroid sparing in vasculitis: Myth or reality?

Glucocorticoids are the cornerstone of therapy for all forms of vasculitis. However, glucocorticoid treatment carries with it the risk of glucocorticoid toxicity. Recent research efforts in vasculitis have emphasized investigation into strategies that reduce glucocorticoid exposure. These strategies include the adoption of rapid-acting steroid-sparing agents, reduced-dose glucocorticoid induction regimens, the early introduction of steroid-sparing agents for maintenance therapy, and the extension of maintenance therapy to minimize glucocorticoid exposure associated with disease relapse. These are critical advances to move us toward the goal of glucocorticoid-free treatment of vasculitis. The evidence supporting each of these strategies and directions for future research are explored.

CanVasc consensus recommendations for the use of avacopan in antineutrophil cytoplasm antibody-associated vasculitis: 2022 addendum

OBJECTIVE

In 2020, the Canadian Vasculitis Research Network (CanVasc) published their updated recommendations for the management of antineutrophil cytoplasm antibody (ANCA)-associated vasculitides (AAV). The current addendum provides further recommendations regarding the use of avacopan in AAV based on a review of newly available evidence.

METHODS

An updated systematic literature review on avacopan (formerly, CCX168) using Medline, Embase, and the Cochrane Library was performed for publications up to September 2022. New recommendations were developed and categorized according to the EULAR grading levels, as done for previous CanVasc recommendations. A modified Delphi procedure and videoconferences were used to reach ≥80% consensus on the inclusion, wording and grading of each recommendation.

RESULTS

Three new recommendations were developed. They focus on avacopan therapy indication and duration, as well as timely glucocorticoid tapering.

CONCLUSION

These 2022 addended recommendations provide rheumatologists, nephrologists, and other specialists caring for patients with AAV with guidance for the use of avacopan, based on current evidence and consensus from Canadian experts.

Place de l’avacopan dans le traitement de la vascularite associée aux ANCA What role for avacopan in the treatment of ANCA-associated vasculitis?

Recent experimental data have revealed the complement, and more specifically the C5a compound, plays a major role in the pathophysiology of ANCA associated vasculitis (AAV). The development of avacopan, an oral inhibitor of C5a receptor, has allowed to test the blockade of this immunological pathway, initially in a murine animal model of the disease, followed by a preliminary, phase 2 therapeutic trial in human disease, with promising results. An international phase 3 trial published in 2021 demonstrated that avacopan can be used instead of corticosteroids for the induction therapy of AAV, in association with an immunosuppressive drug such as cyclophosphamide or rituximab. The adjunction of this new-generation immunosuppressive drug does not increase the infectious risk, but seems to amplify the improvement of renal function during the initial treatment of renal vasculitis. These results have led to the recent registration of avacopan, opening new therapeutic options in AAV. © 2022 Published by Elsevier Masson SAS on behalf of Société francophone de néphrologie, dialyse et transplantation.

C5a receptor antagonism coming of age for vascular pathology

The Food and Drug Administration recently approved the new drug avacopan for a relatively rare disease, anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis. Avacopan is an antagonist of receptor-1 for anaphylatoxin C5a (C5aR₁) that is the first one to meet all expectations of an orally bioavailable drug. Pharmacological effects of C5a on vascular tissue are reviewed; they are essentially indirect, via resident or infiltrating leukocytes, and largely mediated by vasoconstrictor prostanoids that are potentially thrombogenic. The in vivo acute neutropenic effect of C5a and various responses of isolated neutrophils to the peptide have been exploited in the preclinical development of avacopan, but not the prominent hemodynamic responses. Possible clinical risks and extension of therapeutic C5aR₁ blockade are discussed. Therapeutic intervention on the blood-derived peptide C5a and on its G protein coupled receptor for specific forms of vascular injury contrasts with other current research approaches in vascular pathology, such as investigating the roles of cytokines and intracellular signaling.

Avacopan, a Selective C5a Receptor Antagonist, for Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis

Avacopan, an orally administered C5a receptor (C5aR) antagonist, has been approved for the treatment of microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) in Japan and the United States. In ADVOCATE Phase III clinical trial, patients with active MPA or GPA received either 30 mg avacopan twice daily or prednisone on a tapering schedule in combination with rituximab or cyclophosphamide (followed by azathioprine). The trial met its two primary endpoints: avacopan showed non-inferiority to prednisone for achieving remission at week 26 (avacopan, 72.3%; prednisone, 70.1%; p < 0.001 for non-inferiority and p = 0.24 for superiority) and superiority for maintaining remission at week 52 (65.7% for avacopan, 54.9% prednisone, p < 0.001 for non-inferiority and p = 0.007 for superiority). Of several key secondary endpoints tested, the glucocorticoid toxicity index (GTI)-cumulative worsening score and GTI-aggregate improvement score were significantly lower in the avacopan group than in the prednisone group at both weeks 26 and 52. Serious adverse events related and unrelated to the worsening vasculitis were reported at 10.2% and 37.3% in the avacopan group and at 14.0% and 39.0% in the prednisone group, respectively. Avacopan has set the stage for the semi-glucocorticoid-free or glucocorticoid-free treatment of MPA and GPA.

Renal diseases and the role of complement: Linking complement to immune effector pathways and therapeutics

The complement system is an ancient and phylogenetically conserved key danger sensing system that is critical for host defense against pathogens. Activation of the complement system is a vital component of innate immunity required for the detection and removal of pathogens. It is also a central orchestrator of adaptive immune responses and a constituent of normal tissue homeostasis. Once complement activation occurs, this system deposits indiscriminately on any cell surface in the vicinity and has the potential to cause unwanted and excessive tissue injury. Deposition of complement components is recognized as a hallmark of a variety of kidney diseases, where it is indeed associated with damage to the self. The provenance and the pathophysiological role(s) played by complement in each kidney disease is not fully understood. However, in recent years there has been a renaissance in the study of complement, with greater appreciation of its intracellular roles as a cell-intrinsic system and its interplay with immune effector pathways. This has been paired with a profusion of novel therapeutic agents antagonizing complement components, including approved inhibitors against complement components (C)1, C3, C5 and C5aR1. A number of clinical trials have investigated the use of these more targeted approaches for the management of kidney diseases. In this review we present and summarize the evidence for the roles of complement in kidney diseases and discuss the available clinical evidence for complement inhibition.

Vasculitis therapy refines vasculitis mechanistic classification

The primary vasculitides constitute a heterogeneous group of immune mediated diseases of incompletely understood pathogenesis currently classified by the size of blood vessels affected (Chapel Hill classification). In recent years, several drugs with well-characterized immunological targets have been tested in clinical trials in large vessel vasculitis and small vessel vasculitis. Such trials provide "reverse translational" or bedside to bench information about underlying pathogenic mechanisms. Therefore, the aim of this systematic literature review was to examine the evidence base for a more refined mechanistic immunological classification of vasculitis. A total of 40 studies (20 randomized controlled trials (RCTs), 16 prospective studies, 1 retrospective cohort study and 3 case series) were included for full qualitative assessment. RCTs concerning biologic therapy for large vessel vasculitis mainly supports interleukin 6 receptor inhibition (tocilizumab). RCTs concerning biologic therapy for granulomatosis with polyangiitis and microscopic polyangiitis mainly support anti-CD20 treatment (rituximab) and complement inhibition with a small molecule C5a receptor antagonist (avacopan) is an emerging treatment option. The biologic treatment of eosinophilic granulomatosis with polyangiitis is centered around interleukin 5 inhibition (mepolizumab). Studies on tumor necrosis factor alpha inhibition (adalimumab, infliximab, and etanercept) showed negative results in giant cell arteritis but some effect in Takayasu arteritis. Taken together, clinical studies with cytokine and cell specific drugs are dissecting the heterogeneous immunopathogenic mechanisms of vasculitis and support a mechanistic immunological classification. Especially, cytokine antagonism is pointing towards immunological distinctions between eosinophilic granulomatosis with polyangiitis and granulomatosis with polyangiitis/microscopic polyangiitis and differences between giant cell arteritis and Takayasu arteritis.

C3 glomerulopathy and atypical hemolytic uremic syndrome: an updated review of the literature on alternative complement pathway disorders

The complement system plays a significant role within the pathological process of C3 glomerulopathy (C3GP) and atypical hemolytic uremic syndrome (aHUS). In daily practice, clinicians should differentiate the subgroups of C3GP because of they should apply different treatment modalities. In the past, C3GP was considered as a part of membranoproliferative glomerulonephritis (MPGN). MPGN is defined as glomerular capillary thickening secondary to the synthesis of the new glomerular basement membrane and mesangial cellular hyperplasia with mesangial matrix expansion. Atypical hemolytic uremic syndrome is an ultra-rare disease that can be outlined by the triad of Coombs negative microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Recent advances demonstrated that these diseases share common abnormalities of the control of the alternative complement system. Therefore, nowadays, most researchers advocate that there may be overlap in the pathogenesis of C3GP and aHUS. This review will provide recent novel mechanisms and treatment options in these diseases. For the purposes that we mentioned above and to help clinicians, we aimed to describe the etiology, pathophysiology, and treatment of C3GP and aHUS in this comprehensive review.

Antineutrophil cytoplasmic antibody associated vasculitides with renal involvement: Open challenges in the remission induction therapy

Renal involvement with rapidly progressive glomerulonephritis is a common manifestation of antineutrophil cytoplasmic antibody (ANCA) associated vasculitides, which is characterized by end-stage renal disease and high mortality rates in untreated and/or late referral patients. The long-term renal survival has improved dramatically since the addition of cyclophosphamide (CYC) and recently of rituximab (RTX) in association with corticosteroids in the remission induction therapeutic regimens. However, renal prognosis remains unfavorable for many patients and the mortality rate is still significantly high. In this review, we analyze the open challenges to be addressed to optimize the induction remission therapy, principally in patients with advanced kidney failure. This concern the first-line therapy (CYC or RTX) based on different parameters (estimated glomerular filtration rate at baseline, new or relapsed disease, ANCA specificity, tissue injury, safety), the role of plasma exchange and the role of new therapies. Indeed, we discuss future perspectives in induction remission therapy by reporting recent advances in new targeted therapies with particular reference to avacopan, an orally administered selective C5a receptor inhibitor.