Immunex Corp.’s Enbrel showed promise as a treatment for psoriasis in a Phase II study conducted by independent researchers, who presented results at the 60th Annual American Academy of Dermatology Conference in New Orleans.
In the study, 112 patients with moderate to severe plaque psoriasis were randomized to receive 25 mg of Enbrel or placebo subcutaneously twice a week for six months. The study showed that 56 percent of patients treated with Enbrel had at least a 75 percent improvement over a six-month period, compared to 5 percent of patients receiving placebo. The primary endpoint of the study was the proportion of patients achieving a 75 percent improvement in the Psoriasis Area and Severity Index (PASI) after three months.
“Enbrel is the first biologic that has been introduced to the dermatologist’s office as a resource,” said Kris Greco, spokeswoman for Seattle-based Immunex. “We are pleased with the results of this study.”
There was more good news for Immunex. Thirty percent of patients treated with Enbrel achieved a PASI of 75 at three months vs. 2 percent of those receiving placebo (p<0.0001). After six months of study, 21 percent of Enbrel patients achieved PASI 90, compared to none receiving placebo.
The study also looked at the ability of the monoclonal antibody infliximab (Centocor Inc.’s Remicade) to treat psoriasis. The open-label extension trial was designed to determine whether those who had a favorable response to infliximab in an initial randomized 10-week study could maintain the benefits of a PASI improvement of greater than or equal to 50 percent. In the original trial, 82 percent and 73 percent of patients in the 5 mg/kg and 10 mg/kg treatment groups, respectively, experienced a 75 percent improvement in their PASI rating at week 10, following three doses of infliximab (at weeks zero, two and six).
A total of 29 patients who received the three doses of infliximab were observed in the open-label extension study through 26 weeks. The data showed that 55 percent of the patients sustained their response for six months without re-treatment and maintained a greater than or equal to 50 percent improvement in their PASI rating. Also, 48 percent of patients maintained a 75 percent improvement in PASI over the same study period.
For Immunex, a psoriasis approval isn’t even next in line in fact, it could be two approvals away. Enbrel, a tumor necrosis factor inhibitor, is indicated for reducing signs and symptoms and inhibiting the progression of structural damage in patients with moderately to severely active rheumatoid arthritis. It can be used in combination with methotrexate in patients who do not respond adequately to methotrexate alone. It also is indicated for reducing signs and symptoms of moderately to severely active polyarticular-course juvenile rheumatoid arthritis in patients who have had an inadequate response to one or more DMARDs. And it is indicated for reducing signs and symptoms of active arthritis in patients with psoriatic arthritis, and again Enbrel can be used in combination with methotrexate in patients who do not respond adequately to methotrexate alone.
Immunex has initiated a Phase II/III psoriasis trial that is aiming to enroll about 600 patients. Greco listed the goal for Enbrel psoriasis approval as 2004, but Enbrel is in two Phase III trials for other indications that are expected to reach filing status sooner.
“We are looking at ankylosing spondylitis as well as Wegener’s [granulomatosis],” she told BioWorld Today. “We would then have psoriasis follow that.”
Immunex’s stock (NASDAQ:IMNX) rose 22 cents Friday to close at $28.54.