What is Biology Good For?
Treating Rheumatoid Arthritis Through Biotechnology: ENBREL



Rheumatoid Arthritis - Background of the Disease

Arthritis literally means means "inflammation (=itis) of a joint (=arthro)", and refers to a group of diseases that cause pain, swelling, stiffness and loss of motion in the joints, and also in the muscles, tendons, ligaments, and bones. Both children and adults can develop almost all types of arthritis. [Quote]

Rheumatoid Arthritis (RA) is a chronic inflammatory disease that chiefly affects the membranes of various joints in the body. RA and
Juvenile Rheumatoid Arthritis (JRA) are diseases that strike adults and children and can cause painful joint swelling, deformity, stunted growth and increased mortality. According to the Arthritis Foundation, JRA affects approximately 50,000 children in the United States. The disease can impair a child's ability to take part in physical activities, make daily activities such as schoolwork more difficult and affect a child's physical appearance.

What causes Arthritis?

The disease is considered an autoimmune disease that is acquired (perhaps after a viral infection?) and in which genetic factors appear to play a role. Autoimmune means that the person's body begins attacking and destroying it's own tissues. Other examples of autoimmune diseases are Diabetes and Multiple Sclerosis. In all of these disorders, the exact cause of the autoimmune response is not known.

In RA and JRA, the body produces proteins, called cytokines, that invade the joints and cause their linings to become swollen and painful. One of the cytokines that plays a major role in this process is called tumor necrosis factor (TNF). Although everyone needs some TNF to help their immune system, researchers have found that people living with RA have elevated levels of TNF in their joints. Elevated levels of TNF are thought to be related to swelling, pain, and other effects of RA.

ENBREL: a new way to manage the symptoms of RA and JRA

ENBREL is a recombinant protein made by the Biotechnology company Immunex . ENBREL is very similar to a human protein called Tumor Necrosis Factor (TNF) Receptor. The TNF Receptor is found found naturally in the body and normally works to bind TNF in healthy people. However, people with RA live with excess levels of TNF in their bloodstream, which can cause or exacerbates the symptoms of arthritis.

ENBREL is a modified, injectable form of the TNF Receptor that works by capturing the excess TNF in the bloodstream of people with RA or JRA. By acting as a "molecular sponge" to mop up excess levels of TNF, ENBREL brings the levels of TNF in the bloodstream down to normal levels and lessens the symptoms of RA. The binding of Enbrel to TNF renders the TNF inactive, resulting in significant reduction in inflammatory activity.

How Effective is ENBREL?

Enbrel has been studied in thousands of patients from ages four to adult.
Seventy-four percent of the study participants demonstrated a clinical response to Enbrel, measured by the RA and JRA Definition of Improvement.

Medical studies have shown that ENBREL can work as early as two weeks, with most people deriving maximum benefits within three months. At 3 months, two out of three people were better able to

Perform daily activities
Dress and groom themselves
Get out of bed
Reach and grip objects

has been so successful in fighting arthritis that there is a 1,000 patient waiting list for it. At present about 350,000 patients are using the drug. The drug had slightly over $750 million in sales in 1999, making it the fastest biotech launched drug in history. The down side of this injectable drug is that it costs about $12,000 per year to use. Weighed against this cost is the fact that methotrexate, a standard therapy for RA and JRA, costs only about $1,500 per year and comes in pill form.

Althought this drug has a high cost, its benefits are clear for patients with rheumatoid arthritis. "Children with JRA face the possibility of a lifetime of pain and disability," said Daniel Lovell, M.D., M.P.H., a pediatric rheumatologist at Children's Hospital Medical Center of Cincinnati. "Rheumatologists have had limited options to treat children with moderate to severe arthritis. The approval of Enbrel for JRA opens a new era of hope for these children, teen-agers and their families."

Information for this Good For was obtained from the following sources:
ENBREL Backgrounder

FDA Approves Enbrel for JRA
Rheumatoid Arthritis- Enbrel and TNF- Part II


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1. What is TNF and what does it do to cause or increase the symptoms of Rheumatoid Arthritis?
2. What does ENBREL do to TNF in the body of patients with Rheumatoid Arthritis?
3. How much more expensive is ENBREL than Methotrexate, the standard drug for treatment of arthritis?
