Opportunities for future biological therapy in SLE

Newer drugs for the treatment of lupus nephritis

This article first reviews the current treatment of lupus nephritis, with a focus on the most serious forms, that is, the proliferative subtypes. Current standards for treatment have been developed empirically. Corticosteroids form the basis of all regimens. Cyclophosphamide given intravenously for prolonged periods is the current gold standard. Azathioprine can be regarded as an effective drug for maintenance treatment of lupus nephritis. Studies on its efficacy in schedules for remission induction are in progress. It has been learned from studies on 'conventional' immunosuppression that randomised, clinical trials should comprise large numbers of patients and a follow-up of many years to elucidate differences between effective strategies. These requirements are not met by any of the 'new' treatments we discuss in this review. There is only limited experience in patients with lupus nephritis with drugs that are currently used for immunosuppression in other autoimmune diseases, such as methotrexate, cyclosporin and high-dose intravenous gammaglobulins, nor with new immunosuppressive drugs that have been developed for immunosuppression in organ transplantation (mycophenolate mofetil, tacrolimus, fludarabine and cladribine). Hormonal therapy with the weak androgen prasterone (dehydroepiandrosterone; DHEA) has no role in treatment of active lupus nephritis. There are interesting experiences with agents that have evolved from progress in immunobiology and in our understanding of immunological processes. These modalities enable more specific immunosuppression and include monoclonal antibodies directed at immune cells, cytokines and components of the complement system, constructs developed to induce tolerance in pathogenic B cells, and gene therapy. Finally, we review data on autologous bone marrow transplantation in patients with systemic lupus erythematosus. We conclude that some strategies (like mycophenolate mofetil) are good candidates for further investigation in large-scale, prospective, randomised trials with prolonged follow-up (which are almost by definition hard to perform). Most new biological agents still are in a pre-clinical phase.

CTLA4Ig inhibits T cell-dependent B-cell maturation in murine systemic lupus erythematosus

Long-term administration of CTLA4Ig prevents the onset of disease in systemic lupus erythematosus-prone (SLE-prone) NZB/NZW F1 mice. To determine the mechanism of this effect, we engineered an adenovirus that expresses murine CTLA4Ig. Administration of a single high dose of this virus results in long-term expression of CTLA4Ig in the serum and absence of an immune response to the adenoviral vector. We administered Ad-CTLA4Ig to 19- to 22-week-old NZB/NZW F1 mice and evaluated the effect on anti-DNA antibody-producing B cells. We show that CTLA4Ig has a beneficial effect on murine SLE for as long as it is present in the serum. This effect is associated with decreased expansion of both the IgM and IgG autoreactive B-cell population, inhibition of immunoglobulin class switching, decreased frequency and altered pattern of somatic mutation, and a marked decrease in the numbers of activated CD4-positive T cells. In contrast, intrinsic B-cell hyperreactivity and the survival of plasma cells in the bone marrow, both of which are less dependent on T-cell help, appear to be unaffected by CTLA4Ig. High-dose CTLA4Ig did not induce permanent tolerance in this autoimmune disease model. Furthermore, although the mice survived in a conventional housing facility, treatment with Ad-CTLA4Ig was immunosuppressive.