Biologic medications, specifically tumor necrosis factor-alpha (TNF-alpha) blockers, are considered a promising new therapy for the treatment of psoriatic arthritis (PsA), especially in people who have moderate to severe cases of the disease. For the most part, candidates for therapy with biologic response modifiers, or biologics, have not responded to or cannot tolerate more conventional forms of treatment. The following biologic agents are currently approved by the Food and Drug Administration (FDA) for the treatment of psoriatic arthritis:
Etanercept (Enbrel®) became the first biologic medication approved by the FDA for treating the signs and symptoms of psoriatic arthritis in 2002. Now, Enbrel is also indicated for inhibiting the progression of joint destruction and improving physical function in patients who have psoriatic arthritis. Enbrel is a man-made protein that acts like a sponge, soaking up TNF-alpha and blocking it from causing inflammation. It is given as an injection that can be administered at home.
According to clinical studies, after six months of treatment, Enbrel was proven effective at reducing the number of tender and swollen joints in patients with psoriatic arthritis. Nearly two out of five patients experienced a 50 percent improvement in arthritis severity scores. These scores are based on the severity of swelling in and around the joints, joint tenderness, pain, physical function and morning stiffness. The results could be seen after four weeks of treatment.
The side effects associated with Enbrel range from mild to severe. Mild side effects include itching, pain, swelling and redness at the site of the injection. Nasal and throat irritation, dizziness and headaches have also been noted.
Since Enbrel can suppress the immune system, the more severe side effects include an increased risk for an infection such as tuberculosis. There are also cases linking the use of Enbrel to multiple sclerosis and other diseases of the central nervous system. Reports of an increased risk of congestive heart failure have prompted doctors to use caution when patients have already been diagnosed with that condition. Finally, studies indicate there may be an association between Enbrel and an increased risk of cancer, specifically lymphoma.
Adalimumab (Humira®) was approved by the FDA in 2005 for treating active psoriatic arthritis. It is a synthetic, self-administered injection taken every two weeks and is used for reducing the signs and symptoms of psoriatic arthritis. It blocks TNF-alpha production, which slows the destruction of the joints caused by the disease and improves physical function in adults.
In a 24-week study of patients with psoriatic arthritis, adult patients who had failed previous nonsteroidal anti-inflammatory drug treatments experienced significantly greater improvement in their joint and skin disease symptoms when compared to placebo. The improvements were seen in as little as two weeks after starting treatment and continued to improve over time.
Humira is known to cause allergic-like reactions as well as reduced levels of platelets and red blood cells. It has also been associated with serious infections, such as tuberculosis, sepsis and fungal infections. Humira may worsen the symptoms of central nervous system diseases, such as multiple sclerosis. A link is also being studied between Humira and an increased risk of cancer.
Infliximab (Remicade®) was approved by the FDA for the treatment of PsA in 2005. Unlike Enbrel or Humira, Remicade is a monoclonal antibody given in three separate 2 or 3 hour intravenous infusions in a doctor's office. Initially, the drug is given three times within six weeks, and then it may be administered every eight weeks. It works by lowering the amount of TNF-alpha to more normal levels.
According to a large-scale clinical study of the drug, 27 percent of patients with psoriatic arthritis who took Remicade experienced a 70 percent improvement in their arthritic symptoms when compared to placebo. In addition, an analysis of X-rays revealed clinical evidence that the drug is successful at inhibiting the structural progression of the disease.
However, serious side effects have been associated with Remicade's administration.
These include difficulty breathing and low blood pressure. Rash, itching, fever and chills may also occur during or shortly after administration and could indicate an allergy to the drug. Allergies are more common among patients who develop antibodies to Remicade and are less likely to occur in patients who are taking drugs that suppress the immune system, such as methotrexate. Decreased white and red blood cell levels and decreased platelet counts have been reported in patients who are taking Remicade, as has vasculitis, an inflammation of the blood vessels.
Biologics Are Not for Everyone
Although biologic medications are considered as promising options for the treatment of psoriatic arthritis, their effectiveness varies from person to person, and in some people they may not work at all. For others, one biologic may not work as well as another. Some people may not be considered candidates because of the risk of serious side effects.
Biologic medications are not generally recommended if a person's immune system is already significantly compromised. People with active infections may not be eligible for treatment, and if a major infection develops while taking a biologic, it is usually recommended that the medication be temporarily stopped. In addition, screening for tuberculosis or other hidden infections may be required before a treatment is started. Biologic medications are also not advised for people who are pregnant, who have a history of heart failure or for the elderly.
It is important to note that biologic medications are very complex medications. They require decades to research and develop. The high cost of creating these medications is one reason why their annual use can range from $10,000 to $25,000, depending on the dose and frequency of the treatment. Some health insurances cover the use of these treatments in part or in full. Finally, the potential effects of biologics on the immune system are still being evaluated. Anyone who is considering a biologic medication should talk with his or her doctor about the short-term and long-term side effects and risks and carefully weigh those against the risks of other treatment