Approval sought for new psoriatic arthritis drug
Enbrel could get fast-track review by the U.S. Food and Drug Administration
First posted July 17, 2001
Immunex Corp. of Seattle has asked the U.S. Food and Drug Administration (FDA) to conduct a "priority review" of its drug etanercept (brand name Enbrel®) for the treatment of psoriatic arthritis. If the FDA grants approval, Enbrel would be the first drug approved directly by the FDA for this purpose.
Psoriatic arthritis is a type of arthritis that affects the joints and the soft tissues around the joints. It is similar to rheumatoid arthritis and related to the skin disease psoriasis. Psoriatic arthritis affects between 10 percent and 30 percent of the more than 7 million people in the U.S. who have psoriasis.
Although many therapies are used today for psoriatic arthritis, none are officially approved by the FDA for the disease. Immunex, in conjunction with marketing partner Wyeth-Ayerst Laboratories, has asked for an expedited review of Enbrel because of the lack of approved therapies. If the FDA decides within the next 60 days to grant "priority review," the agency would be required to act on the Enbrel application within six months. Normal review can take a year or more.
Immunex has filed a supplemental biologics license application (sBLA) with the FDA, based on data collected in phase II and phase III clinical trials. Enbrel is already approved for treating rheumatoid arthritis, so psoriatic arthritis is considered a "supplemental" indication.
"Psoriatic arthritis is a potentially devastating condition that may affect more than 1 million Americans," says Gail M. Zimmerman, NPF president and CEO. "There are no treatments for psoriatic arthritis that are approved by the FDA, and the treatments that are used are limited by their serious side effects and by the fact that they just do not work well for everyone. We are hoping that new treatments such as Enbrel will offer people with psoriatic arthritis safer and more effective ways to treat their disease."
"People who are experiencing symptoms of arthritis -- such as swollen, tender joints -- who also have psoriasis or similar skin symptoms should talk with their physician about the possibility of psoriatic arthritis," Ms. Zimmerman continues. "It is important for people to get an accurate diagnosis, as not all forms of arthritis are treated the same. While psoriatic arthritis is similar in some ways to the better-known rheumatoid arthritis, there are important differences as well."
Enbrel's effectiveness
Data has not yet been released from a 205-patient phase III clinical trial of Enbrel for psoriatic arthritis. An April news release from Immunex said preliminary results indicate that psoriatic arthritis patients "experienced significant improvement in signs and symptoms of their disease, compared to placebo."
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.
Last year, Philip J. Mease, M.D., a rheumatologist at Seattle's Minor & James Medical Center, published the results of a 60-patient study. 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.
Enbrel's effectiveness in treating psoriasis was tracked in the phase III psoriatic arthritis study. Early results are reportedly positive, but Immunex is conducting an ongoing phase II study to look specifically at treating psoriasis with Enbrel. Results are expected in several months.
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, people with certain types of arthritis produce too much TNF-alpha, 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.
| 
