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New treatment approved for psoriatic arthritis

The U.S. Food and Drug Administration (FDA) has approved the drug etanercept (brand name Enbrel) for the treatment of psoriatic arthritis. Physicians can prescribe Enbrel by itself or in combination with methotrexate, another systemic treatment for the disease.

While other therapies are used to treat psoriatic arthritis, Enbrel is the first to receive specific FDA approval for "reducing the signs and symptoms" of active psoriatic arthritis. Psoriatic arthritis affects approximately 23 percent of people with psoriasis.

Enbrel was originally approved for rheumatoid arthritis in 1998, and many physicians are familiar with prescribing it. Patients give themselves injections of the drug under the skin, usually twice per week.

How is it different?
Enbrel is one of many "biologic response modifiers" that have been in development and testing for psoriasis and psoriatic arthritis. This new class of drugs is genetically engineered to block key interactions between cells in the immune system involved in these diseases. Other treatments for psoriasis and psoriatic arthritis, particularly those used in moderate to severe cases, can have a widespread impact on the immune system.

Enbrel blocks the action of a cytokine (cellular "messenger") called tumor necrosis factor-alpha (TNF-alpha) by binding to the site that allows the cell to communicate with other cells. Normally, TNF-alpha plays an important role in our immune system by promoting inflammation to fight infections. For unknown reasons, TNF-alpha is overproduced in the synovial fluid (lubricating fluid of the joints) and tissue of joints as well as the skin of people with psoriatic arthritis and psoriasis.

Thus, TNF-alpha overstimulates inflammation, which leads to painful damage of the joints and connective tissue, as well the development of lesions on the skin.

How effective is Enbrel?
Enbrel is a maintenance drug. Once it is stopped, the symptoms of the disease return. Some patients will begin to experience improvement even after the first injection. Many patients begin to experience improvements in the signs and symptoms of psoriatic arthritis after three to four weeks. By three months, a majority of patients in clinical trials experienced major improvement in both bone and skin disease.

In the last phase III trial before the drug was submitted to the FDA, 62 percent of patients on low doses of methotrexate who also took Enbrel achieved at least a 20 percent improvement in symptoms of psoriatic arthritis (tender and swollen joints, stiffness, pain, etc.) after three months.

Among patients who took Enbrel without methotrexate, 58 percent had at least a 20 percent improvement in their psoriatic arthritis. All patients received 25 milligrams of the drug twice a week and were compared to an equal number of patient who received no Enbrel.

Enbrel also appears to help improve the skin. After six months, 43 percent of patients with moderate to severe psoriasis achieved a 50 percent improvement in a typical lesion, and a 47 percent improvement in their psoriasis overall.

The trial included 205 patients at 17 clinics across the country.

What are the side effects?
In clinical trials, the principal side effects related to Enbrel were minor reactions at the site of injection (36 percent of patients). The injection site reactions have been reported to be like mosquito bites that tend to fade by themselves and are no reason to stop the medication.

Because Enbrel blocks the action of a cell (TNF-alpha) that normally plays an important role in the immune system, it is believed to affect a person's ability to fight infections. Physicians are encouraged to exercise caution when considering the use of Enbrel in patients with a history of recurring infections. However, in clinical trials, infectious events such as upper respiratory and urinary infections occurred with equal frequency between those taking Enbrel and those not, which is reassuring regarding the issue of predisposition to infection.

Recently, the FDA recommended that doctors test patients for tuberculosis (TB) before they take a drug similar to Enbrel called Remicade. Remicade is also an anti-TNF inhibitor, and it appears to contribute to the emergence of TB in patients who have a silent, or dormant, infection with TB. The same recommendation has not been made for Enbrel, but some rheumatologists nonetheless test any patient for dormant TB prior to prescribing anti-TNF therapy.

People with known multiple sclerosis should not take Enbrel. Since the drug was approved for rheumatoid arthritis, a handful of new or exacerbated multiple sclerosis cases has been seen. Physicians should advise their patients about this issue, but the risk is very small and in the great majority of patients outweighed by the potential benefits of the drug.

Based on all of the safety information available on Enbrel since the drug has been approved for rheumatoid arthritis, the FDA requires the warning label on the medication to state that the there is a risk of serious, even life-threatening, infections in some people, especially if their immune system is already compromised. The drug may be temporarily discontinued in people who have active infections, such as lung infections or flu.

Unlike the situation with methotrexate patients, regular blood tests to determine whether Enbrel is harming the liver will not be required.

How do I get it?
Immunex is requiring patients to join an enrollment program to receive Enbrel, but has not stated how long patients must wait before receiving the drug. According to company spokesperson Robin Shapiro, part of the reason the program is in place is to help the company monitor demand for the drug.

Patients who call the enrollment program (1-888-4-ENBREL) are asked for their names, address and mailing information. The company sends a package of information, including a release form patients are required to get their physician to sign. Before patients are placed on the waiting list, they need to send the signed form back to the company, as well as documentation that their insurance company will cover the drug.

According to Immunex, approximately 3,000 people per month are being moved from the waiting list to the active list to begin receiving Enbrel. Company officials say they do not know how many people are now on the waiting list, but that since 1998, Enbrel has been prescribed to 120,000 people.

Depending on where the drug is purchased, Enbrel costs approximately $12,000 per year.

Currently, Medicare does not cover prescription drugs, and so Enbrel is not covered. However, Immunex does report it has had great success working with people to get their private insurance companies to cover the treatment.

By calling the enrollment program number, patients can also talk to insurance specialists who can help walk them through the insurance process. The same number also puts patients in touch with nurses and allows them to order free needle disposal containers and sign up for prescription reminders, e-mail alerts and newsletters about Enbrel. The line is staffed Monday through Friday, from 9 a.m. to 9 p.m. EST.