Belimumab for systemic lupus erythematosus

Genetics and novel aspects of therapies in systemic lupus erythematosus

Autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis, autoimmune hepatitis and inflammatory bowel disease, have complex pathogeneses and the factors which cause these disorders are not well understood. But all have in common that they arise from a dysfunction of the immune system, interpreting self components as foreign antigens. Systemic lupus erythematosus (SLE) is one of these complex inflammatory disorders that mainly affects women and can lead to inflammation and severe damage of virtually any tissue and organ. Recently, the application of advanced techniques of genome-wide scanning revealed more genetic information about SLE than previously possible. These case-control or family-based studies have provided evidence that SLE susceptibility is based (with a few exceptions) on an individual accumulation of various risk alleles triggered by environmental factors and also help to explain the discrepancies in SLE susceptibility between different populations or ethnicities. Moreover, during the past years new therapies (autologous stem cell transplantation, B cell depletion) and improved conventional treatment options (corticosteroids, traditional and new immune-suppressants like mycophenolate mofetile) changed the perspective in SLE therapeutic approaches. Thus, this article reviews genetic aspects of this autoimmune disease, summarizes clinical aspects of SLE and provides a general overview of conventional and new therapeutic approaches in SLE.

Which dose of steroids and which cytotoxics for severe lupus?

There have been a number of major advances in the treatment of systemic lupus erythematosus and we are now in the era of biologic therapies for this multisystem autoimmune disorder. There has been a greater awareness of the toxicities of the traditional therapies including the recognition that the doses of corticosteroids used in the past have been excessive, resulting in unacceptable toxicities. Other advances have included the development of lower cumulative doses of cyclophosphamide and the widespread acceptance of mycophenolate mofetil for the treatment of lupus nephritis. This review addresses the current management of severe lupus with corticosteroids and cytotoxic agents.

[Recommendations on the use of belimumab in systemic lupus erythematosus. GEAS-SEMI Clinical Practice Guide]

Biological therapies are based on the administration of various types of synthetic molecules related to the immune response. Their use has spread in recent years to the field of systemic autoimmune diseases, particularly to systemic lupus erythematosus (SLE). Until 2011, these diseases were not included in the therapeutic indications approved by international regulatory agencies. Therefore, the use of biological therapies was restricted to clinical trials and to compassionate use for cases refractory to standard treatments (off-label use), which require the approval of the Health Ministry. In 2011, belimumab, a human monoclonal antibody that specifically binds to the soluble form of the protein human B lymphocyte stimulator BlyS, was approved for use in patients with SLE. Because the clinical information on the use of this new drug in patients with SLE has only been obtained from the results of randomized trials, the Study Group of Autoimmune Diseases (GEAS) of the Spanish Society of Internal Medicine (SEMI) has developed therapeutic guidelines. These guidelines are based on the current scientific evidence on the use of belimumab in SLE patients in the clinical practice.

New treatment options for lupus - a focus on belimumab

Belimumab is the first biologic approved for patients with systemic lupus erythematosus (SLE). Belimumab is the first of a new class of drug targeting B cell-stimulating factors or their receptors to reach the market. Its target, BLyS, also known as BAFF (B cell-activating factor from the tumor necrosis factor family), is a type II transmembrane protein that exists in both membrane-bound and soluble forms. Additionally to a robust rational from murine experiments conducted in lupus prone mice, BLyS circulating levels are increased in SLE patients. After the negative results of a Phase II trial, two Phase III trials met their primary endpoints. Some SLE patients are still refractory to the standard options of care or necessitate prolonged high-dose corticotherapy and/or long-term immunosuppressive regimens. However, some experts still feel that the effect of this biologic might not be clinically relevant and blame the use of the new systemic lupus response index as well as the discrepancies between both trials and the noninclusion of the severe form of the disease as nephritis. In this review, we aim to discuss the characteristics of belimumab, critically evaluate the different steps of its development, and consider its future place in the arsenal against SLE, taking into account the patients’ perspectives.

The role of B cells in solid organ transplantation

The role of antibodies in chronic injury to organ transplants has been suggested for many years, but recently emphasized by new data. We have observed that when immunosuppressive potency decreases either by intentional weaning of maintenance agents or due to homeostatic repopulation after immune cell depletion, the threshold of B cell activation may be lowered. In human transplant recipients the result may be donor-specific antibody, C4d+ injury, and chronic rejection. This scenario has precise parallels in a rhesus monkey renal allograft model in which T cells are depleted with CD3 immunotoxin, or in a CD52-T cell transgenic mouse model using alemtuzumab to deplete T cells. Such animal models may be useful for the testing of therapeutic strategies to prevent DSA. We agree with others who suggest that weaning of immunosuppression may place transplant recipients at risk of chronic antibody-mediated rejection, and that strategies to prevent this scenario are needed if we are to improve long-term graft and patient outcomes in transplantation. We believe that animal models will play a crucial role in defining the pathophysiology of antibody-mediated rejection and in developing effective therapies to prevent graft injury. Two such animal models are described herein.