First "official" drug for psoriatic arthritis could be on the horizon
Enbrel to be submitted for approval later this year
First posted April 2, 2001
Prompted by encouraging results from a late-stage clinical trial, Immunex Corp. of Seattle has announced it will seek U.S. Food and Drug Administration (FDA) approval to treat psoriatic arthritis with its drug etanercept (brand name Enbrel®). Although many medications are used to treat psoriatic arthritis, at this time no drugs are approved by the FDA directly for that purpose.
"There never has been any drug specifically approved for psoriatic arthritis, so our study is probably ground-breaking in itself," said an Immunex spokesperson. "We are confident that our data looks good, and that's why we're moving as quickly as possible with the application [to the FDA]."
Immunex expects to file a supplemental Biological License Application (BLA) with the FDA around mid year. Enbrel, marketed by Immunex in conjunction with Wyeth-Ayerst Laboratories, is already approved for treating rheumatoid arthritis, so psoriatic arthritis is considered a "supplemental" indication.
The company will seek a "priority review," which if granted means the FDA must review and rule on the application within six months. Without priority review, the FDA could take a year or more to analyze the application.
Immunex is still analyzing the data from its 205-patient phase III clinical trial, but preliminary results indicate that psoriatic arthritis patients "experienced significant improvement in signs and symptoms of their disease, compared to placebo," according to a company news release.
Side effects were said to be "consistent with those reported with Enbrel to date." Those side effects have primarily included injection site reactions, infections and headache, although some serious infections have been reported.
Along with psoriatic arthritis, Enbrel's effectiveness in treating psoriasis also was tracked in the phase III study. Early results are positive, but the company is awaiting more definitive answers from an ongoing phase II study, which is looking specifically at treating psoriasis with the medication.
Enbrel's background
Enbrel works by neutralizing tumor necrosis factor alpha (TNF-alpha), a protein in the body that plays an important role in normal immune function. However, there is too much TNF-alpha in people with certain types of arthritis, which leads to the inflammation around joints. Enbrel binds to TNF-alpha molecules and renders them inactive, thereby stopping the inflammatory processes.
Enbrel is given twice per week as an injection under the skin. Patients can self-inject the medication.
Since being approved for rheumatoid arthritis in 1998, Enbrel has been prescribed "off label" for psoriatic arthritis patients by many physicians. The NPF has heard successful anecdotal reports, and small studies have also shown positive results.
A 60-patient study was conducted by Philip J. Mease, M.D., a rheumatologist at Seattle's Minor & James Medical Center. At three months, psoriatic arthritis had measurably improved in 87 percent of patients treated with Enbrel, compared to 23 percent treated with placebo.
Enbrel is often prescribed in combination with other arthritis therapies, such as methotrexate or prednisone (a systemic steroid). In Dr. Mease's study, 68 percent of patients on Enbrel were able to either discontinue taking methotrexate or to decrease the dose. Similarly, 44 percent stopped taking prednisone and 67 percent decreased the dose.
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