Corticosteroid-Sparing Effect of Etanercept in Idiopathic Panuveitis Resistant to Immunosuppressive Therapy

The current status of biological treatment for uveitis

INTRODUCTION

Noninfectious uveitis represents one of the leading causes of blindness in developed Countries, compromising patients' quality of life and social functioning. The main treatment goals are the control of ocular inflammation, to avert and treat sight-threatening complications, thus preserving and/or restoring visual function.

AREAS COVERED

This manuscript deals with systemic therapy with biologic drugs for noninfectious uveitis. An extensive literature search in the MEDLINE database (via PubMed) has been performed up to June 2020. The major classes of biologic molecules employed in ocular inflammatory diseases have been reviewed, focusing on TNF inhibitors, IL-1, IL-6, IL-17, IL-23 inhibitors, interferons, rituximab, and abatacept efficacy and safety. An overview of most recent developments in the field has been provided as well, with reference to the experience with JAK inhibitors and with biosimilar drugs.

EXPERT OPINION

The development of the concept of targeted therapy and the subsequent introduction of biologic molecules in clinical practice have revolutionized the prognosis of uveitis. The target of a rapid and sustained steroid-free remission of ocular inflammation should be pursued for all patients early in the disease course, in order to have a better chance to improve the final visual outcome.

The use of biologic agents in the management of uveitis

The uveitides are a heterogenous group of ocular inflammatory disorders that account for the third highest cause of blindness worldwide, responsible for 5-10% of visual impairment globally. Up to 35% of patients with uveitis can suffer significant vision loss. To prevent irreversible structural damage and blindness, it is important that the diagnosis and commencement of appropriate therapy occurs promptly. Management includes topical and systemic corticosteroid therapy and conventional immunomodulatory agents, including methotrexate, azathioprine, mycophenolate mofetil and cyclosporin. Significant progress has been made in the past decade in our understanding of the immunopathological pathways that drive intraocular inflammation, allowing the development of targeted therapy with biologic agents. These include TNF-α inhibitors, such as infliximab, adalimumab and etanercept; interleukin blockers, such as tocilizumab and daclizumab; and other targeted therapies, such as rituximab and abatacept. The efficacy of these agents has been studied in cases of severe uveitis that are refractory to conventional immunomodulatory agents and provide exciting results that have revolutionised uveitis management. Though the biologic era has provided a large armamentarium to treat uveitis, ongoing challenges and cases of recalcitrant uveitis remain, posing a challenge to internal medicine physicians. This comprehensive review aims to construct an updated summary on the existing evidence pertaining to the use of biologic agents in the treatment of uveitis. Methods include a systematic search for studies between 2000 and 2018 using PubMed, EMBASE, Ovid MEDLINE and Cochrane libraries.

The Use of Biologic Therapies in Uveitis

Therapy for autoimmune ophthalmic disease is currently evolving. The improved understanding of the abnormal immune response in the various forms of uveitis has resulted in targeted therapy. The aberrations of the immune system have been characterized by atypical cell populations, cytokine expression, and cell-cell interactions. Different patterns of cytokine expression have now been delineated in the abnormal uveal tract with exaggerated and/or abnormal expression of TNF, IL-1, IL-2, IL-6, and IL-17. The development of therapies for other conditions in which these cytokines play an important role has resulted in the availability of biological agents that have been adopted for use in the therapy for uveitis. Adalimumab and infliximab have been the best studied anti-TNF agents and indeed have now been recommended by an expert panel as first-line treatment of ocular manifestations of Behçet's disease and second-line treatment for other forms of uveitis (Levy-Clarke et al. (Ophthalmology, 2013). Other anti-TNF agents have been studied as well. Daclizumab, a monoclonal antibody directed against the IL-2 receptor, has also demonstrated utility in treating uveitis as have some of the anti-IL1 agents. Gevokizumab has been granted orphan drug designation for the treatment of resistant forms of uveitis. Therapies affecting IL-6, including tocilizumab are being studied, and available medications that block antigen presenting cell and T cell interaction such as abatacept have been reported to be effective in uveitis. Interferons as well as rituximab have also been evaluated in small studies. Although these biologic therapies have provided a larger armamentarium to treat uveitis, challenges remain. Uveitis is not a single illness; rather, it is a manifestation of many potential systemic diseases that may have very specific individual therapeutic targets. Identifying and characterizing these underlying diseases is not always achieved, and more importantly, the most effective therapies for each entity have not been defined.

Emerging biologics in the treatment of uveitis

The pathogenic mechanisms underlying uveitis syndromes continue to be evaluated using animal models and in the clinical setting. As the complex interactions between ocular immune cells, proinflammatory cytokines, chemokines and cellular adhesion molecules are uncovered, targeted therapies directed against these immune mediators will continue to be developed. Traditional immunosuppressive medications, such as corticosteroids and steroid-sparing immunomodulatory agents, have demonstrated efficacy in the treatment of uveitic syndromes, but side effects and drug toxicities often limit the use of these medications. The biologic agents, a newer class of medications, target specific immune pathways and have demonstrated efficacy in rheumatologic, dermatologic and neurologic conditions. Biologic therapies (e.g., TNF-alpha inhibitors and IL-2 receptor inhibitor) targeting ocular immune cell surface receptors, cytokines and chemokines continue to be developed and have shown promise in the treatment of uveitis and ocular inflammatory diseases. Clinical and basic aspects of monoclonal antibody therapy for uveitis are presented in this review. Additional studies are needed to further evaluate the role of monoclonal antibodies in the therapeutic armamentarium for uveitis.

Advances in the diagnosis and immunotherapy for ocular inflammatory disease

Significant advances in the diagnosis and therapy for uveitis have been made to improve the quality of care for patients with ocular inflammatory diseases. While traditional ophthalmic examination techniques, fluorescein angiography, and optical coherence tomography continue to play a major role in the evaluation of patients with uveitis, the advent of spectral domain optical coherence tomography and fundus autofluorescence into clinical practice provides additional information about disease processes. Polymerase chain reaction and cytokine diagnostics have also continued to play a greater role in the evaluation of patients with inflammatory diseases. The biologic agents, a group of medications that targets cytokines and other soluble mediators of inflammation, have demonstrated promise in targeted immunotherapy for specific uveitic entities. Their ophthalmic indications have continued to expand, improving the therapeutic armentarium of uveitis specialists.