Arthritis is one of the most common human ailments worldwide. For this reason it is a popular target with pharmaceutical companies. Many biologics have been developed to allow rheumatologists to do more than just treat the symptoms of arthritis pain. Increasingly, biologics are being used to actually change mechanisms of the patient’s immune system and growth factors. This has lead to strong revenue growth in the market for prescription treatments.
Arthritis is a complex family of musculoskeletal disorders. The most crippling of the arthritis family is rheumatoid arthritis. In the United States, approximately 1% to 2% of the population is affected. Women are two to three times more likely to develop RA than men, and the peak incidence occurs between the fourth and sixth decades.
Symptomatic treatments have traditionally been used for patients with arthritis. While these treatments are still used regularly, new disease-modifying therapies have produced the most impressive results in treating more severe types of arthritis. Led by biologic response modifiers, the market for prescription arthritis treatments will exceed $20 billion in 2011, according to Kalorama Information. In particular, drugs such as Remicade or Humira that attack tumor necrosis factor (TNF) have led this market to 7.3% growth in revenues.
Biologic response modifiers are true biologic compounds because they are made from living cells. The homeostatic mechanism of immunity is essential for human survival. Biologic therapy or biotherapy, previously termed immunotherapy, is a broad term used to describe the use of agents derived from natural sources that both augment and suppress the body’s immune activity.
Tumor necrosis factor (TNF) mediates a number of immunologic events indicating it plays an important role in host response to inflammation. TNF stimulates macrophage-mediated antitumor activity, endothelial cells, and granulocytes. Research has shown that TNF-induced effector molecules are responsible for the cytotoxic activities of natural cytotoxic cells that may be important in natural immunity. These cells can cause tumor cell lysis, but also initiate the inflammatory cascade. Leading anti-TNF therapies include Enbrel, Humira, and Remicade. Anti-TNF drugs lead biologic arthritis treatments and all arthritis treatments.
There are other types of biologics that deserve mention. Cyclosporin is a cyclic peptide of 11 amino acid residues with potent immunosuppressive activity but no effect on the acute inflammatory reaction. Glucocorticoids are an immunosuppressant drug category that restrains the clonal proliferation of Th cells, through decreasing transcription of the gene for IL-2; however, they also decrease the transcription of many other cytokine genes.
Azathiprine interferes with purine synthesis and is cytotoxic. Excessive purine synthesis is associated with some cases of gouty arthritis. Both cell-mediated and antibody-mediated immune reactions are depressed by this drug since it inhibits clonal proliferation in the induction phase of the immune response by a cytotoxic action on dividing cells.