Fibromyalgia or multi-organ dysesthesia?

Anti-TNF alpha therapy of rheumatoid arthritis: what have we learned?

Rheumatoid arthritis (RA), a systemic disease, is characterized by a chronic inflammatory reaction in the synovium of joints and is associated with degeneration of cartilage and erosion of juxta-articular bone. Many pro-inflammatory cytokines including TNF alpha, chemokines, and growth factors are expressed in diseased joints. The rationale that TNF alpha played a central role in regulating these molecules, and their pathophysiological potential, was initially provided by the demonstration that anti-TNF alpha antibodies added to in vitro cultures of a representative population of cells derived from diseased joints inhibited the spontaneous production of IL-1 and other pro-inflammatory cytokines. Systemic administration of anti-TNF alpha antibody or sTNFR fusion protein to mouse models of RA was shown to be anti-inflammatory and joint protective. Clinical investigations in which the activity of TNF alpha in RA patients was blocked with intravenously administered infliximab, a chimeric anti-TNF alpha monoclonal antibody (mAB), has provided evidence that TNF regulates IL-6, IL-8, MCP-1, and VEGF production, recruitment of immune and inflammatory cells into joints, angiogenesis, and reduction of blood levels of matrix metalloproteinases-1 and -3. Randomized, placebo-controlled, multi-center clinical trials of human TNF alpha inhibitors have demonstrated their consistent and remarkable efficacy in controlling signs and symptoms, with a favorable safety profile, in approximately two thirds of patients for up to 2 years, and their ability to retard joint damage. Infliximab (a mAB), and etanercept (a sTNF-R-Fc fusion protein) have been approved by regulatory authorities in the United States and Europe for treating RA, and they represent a significant new addition to available therapeutic options.

Treatment options for rheumatoid arthritis: celecoxib, leflunomide, etanercept, and infliximab

OBJECTIVE

To review new pharmacologic agents approved for use in the management of rheumatoid arthritis (RA).

DATA SOURCES

A MEDLINE search (1966-January 2000) was conducted to identify English-language literature available on the pharmacotherapy of RA, focusing on celecoxib, leflunomide, etanercept, and infliximab. These articles, relevant abstracts, and data provided by the manufacturers were used to collect pertinent data.

STUDY SELECTION

All controlled and uncontrolled trials were reviewed.

DATA EXTRACTION

Agents were reviewed with regard to mechanism of action, efficacy, drug interactions, pharmacokinetics, dosing, precautions/contraindications, adverse effects, and cost.

DATA SYNTHESIS

Traditional pharmacologic treatments for RA have been limited by toxicity, loss of efficacy, or both. Increasing discoveries into the mechanisms of inflammation in RA have led to the development of new agents in hopes of addressing these limitations. With the development of celecoxib, a selective cyclooxygenase-2 inhibitor, the potential exists to minimize the gastrotoxicity associated with nonsteroidal antiinflammatory drugs. Leflunomide has been shown to be equal to or less efficacious than methotrexate, and may be beneficial as a second-line disease-modifying antirheumatic drug (DMARD). The biologic response modifiers, etanercept and infliximab, are alternatives that have shown benefit alone or in combination with methotrexate. However, they should be reserved for patients who fail to respond to DMARD therapy. Further studies should be conducted to evaluate the long-term safety and efficacy of these agents as well as their role in combination therapy.

CONCLUSIONS

Celecoxib, leflunomide, etanercept, and infliximab are the newest agents approved for RA. Clinical trials have shown that these agents are beneficial in the treatment of RA; however, long-term safety and efficacy data are lacking.

Antitumor necrosis factor therapy for inflammatory bowel disease: a review of agents, pharmacology, clinical results, and safety

Tumor necrosis factor-alpha (TNFalpha), a proinflammatory cytokine, plays an important role in the pathogenesis of inflammatory bowel disease (IBD). Biotechnology agents including a chimeric monoclonal anti-TNF antibody (infliximab), a humanized monoclonal anti-TNF antibody (CDP571), and a recombinant TNF receptor fusion protein (etanercept) have been used to inhibit TNFalpha activity. Controlled trials have demonstrated efficacy for infliximab in moderately to severely active Crohn's disease (CD) and fistulizing CD sufficient to justify recent U.S. Food and Drug Administration (FDA) approval. Additional trials have been completed in rheumatoid arthritis (RA). Similarly, preliminary controlled trials have suggested efficacy for CDP571 in active CD and RA. Larger controlled trials have demonstrated efficacy for etanercept in RA patients who have failed disease modifying antirheumatic drug (DMARD) therapy leading to FDA approval for RA. Toxicities observed with anti-TNF therapies have included formation of human antichimeric antibodies (HACA) with associated acute and delayed hypersensitivity infusion reactions, human antihuman antibodies (HAHAs), and formation of autoantibodies with rare instances of drug-induced lupus. Several cases of non-Hodgkin's lymphoma also has been described. Future studies should evaluate optimal timing and duration of anti-TNF therapy, the utility of adjuvant medical treatments during anti-TNF therapy, and evaluate long-term safety and efficacy of the various anti-TNF agents.