This invention concerns the discovery of novel autoantigenic peptides useful for the diagnosis and treatment of rheumatoid arthritis.

Summary of Invention:
This invention concerns the discovery of novel autoantigenic peptides useful for the diagnosis and treatment of rheumatoid arthritis. The inventors discovered that substitution of one amino acid for another at specific positions within peptides commonly found within the joints, resulted in the formation of novel autoantigenic peptides. These novel auto-antigenic peptides exhibited an increased affinity for binding the human MHC class II receptor in transgenic mouse models. Subsequent assays performed using the sera from patients with and without rheumatoid arthritis exhibited clinical sensitivity and specificity for rheumatoid arthritis of 80% and 97%, respectively. These results were considered comparable to or better than those obtained using other serum diagnostic biomarkers of rheumatoid arthritis (e.g., rheumatoid factor (RF), cyclic citrullinated peptide [CCP]). Therapeutically, it has been proposed that the novel auto-antigenic peptides of this invention could be bound to other compounds (e.g., toxins), formulated as antigens into vaccines or be used to produce monoclonal antibodies to inhibit or disrupt autoimmune inflammatory responses prior to the onset of rheumatoid arthritis. These and other potential applications hold significant promise for the development of more specific diagnostic tests and more specific, effective and safer products for the treatment of rheumatoid arthritis.

Market Opportunity:
Rheumatoid arthritis affects 1 in 100 people worldwide. In the United States, an estimated 0.5-1% of the population or approximately 2.5 million individuals suffer from rheumatoid arthritis. Early diagnostic assays for rheumatoid arthritis were non-specific and often resulted in a false positive diagnosis. The recent advent of antibodies to citrullinated peptides like ours has allowed for more specific diagnostic assays to be developed and the possibility of early diagnosis. The global market for development of autoimmune diagnostic assays was estimated to be US$250 million in 2005 and is expected to grow to US$410 million by 2010. Prior therapies offered only symptomatic relief from inflammation associated with rheumatoid arthritis. More recently, biologic agents that control autoimmune responses leading up to inflammation and the onset of rheumatoid arthritis have entered the market. The current market for the sale of rheumatoid arthritis therapeutic products is estimated to be more than US$8 billion in the United States and will continue to grow as more individuals are prescribed the disease modifying agents. Some of the most highly prescribed products in this category have already achieved sales in excess of US$500 million per year.