Autoimmune disorders are caused by the body producing an inappropriate immune response against its own tissues. Sometimes the immune system will cease to recognize one or more of the body's normal constituents as "self" and will create autoantibodies - antibodies that attack its own cells, tissues, and/or organs. This causes inflammation and damage and can eventually lead to autoimmune disorders.
There are more than eighty illnesses caused by autoimmunity. Some of the most common types of autoimmune disorders include: rheumatoid arthritis (joints), Crone's disease and ulcerative colitis (inflammatory bowl diseases, IBD), psoriasis (skin), lupus and multiple sclerosis (CNS). A substantial minority of the population suffers from these diseases, which are often chronic, debilitating and life-threatening. It has been estimated that autoimmune diseases are among the ten leading causes of death among women in all age groups up to 65 years.
Rheumatoid arthritis (RA) is a chronic and debilitating autoimmune disease of unknown etiology. It is associated with significant morbidity, as the associated inflammatory processes cause the destruction of cartilage and bone, leading to joint swelling and pain and, ultimately, joint destruction. Up to 90% of patients with severe synovitis have evidence of bone erosion. Current RA therapies hold many limitations, including serious side effects, such as increased risk for cancer and infections, as well as lack of response to current available treatments in some patients, which can generally be accounted for by genetic polymorphism.
RA affects an estimated 2 two million people in the United States and an estimated 20 million individuals worldwide. The annual global prevalence rate of RA is approximately 1-2%, with incidence of approximately 3 per 100,000 new cases per year. In the US in 2005, 1.29 million adults aged over 18 years old were estimated to have RA. It is generally 2- to 3-fold more frequent in women than in men, and can begin to develop at any age, with a peak onset generally between the age group of 25 to 55 years.
In addition to RA, there is clear medical need also in the other autoimmune indications. Inflammatory bowel diseases (IBD) are a group of inflammatory conditions of the colon and small intestine. The main types of IBD are Crohn's disease and Ulcerative Colitis (UC). The differences between Crohn's disease and UC are the location and nature of the inflammatory changes. Crohn's can affect any part of the gastrointestinal tract, from mouth to anus, although a majority of the cases start in the terminal ileum, and it can affect the whole bowel wall. UC, in contrast, is restricted to the colon and the rectum, and manifests itself in the mucosa only (epithelial lining of the gut). The prevalence of IBD is 0.2% in the USA, with approximately 300,000-500,000 people affected.
Psoriasis is a chronic, immune-mediated skin disease that affects about 1-3% of the world's population. In addition to physical and traumatic skin damage, psoriasis also causes psychological damage due to its appearance-altering effects. Psoriasis can be manifested at various degrees of severity, but commonly causes substantial discomfort to patients.
As autoimmune diseases are chronic, they entail long-term drug use by patients, substantially affecting patients' quality of life. Hence, in addition to the obvious need for drugs with better efficacy, in RA and the other autoimmune diseases there is also a need for drugs with better pharmacological properties. Drugs with better pharmacological properties, such as improved bio-availability, will improve delivery to the site of action in the damaged tissue, improving safety and lowering the expected side effect profile. These properties will also enable oral administration instead of sub-cuteneous bolus injections or intra-venus administration, which are problematic methods for chronic administration of drugs. Therefore, there is a real need for innovative drugs with efficacy superior to existing treatments and with the absence of the severe side effects.