Senior Staff Writer

A day before Biogen Inc.'s psoriasis drug, Amevive, was scheduled to appear before the FDA's Dermatologic and Ophthalmic Drugs Advisory Committee, the agency posted to its website a briefing document suggesting the product, while effective, may need additional time in the clinic.

The company's stock (NASDAQ:BGEN) fell $1.12 Wednesday to close at $40.36.

Cambridge, Mass.-based Biogen is seeking approval of Amevive (alefacept) for the treatment of patients with chronic plaque psoriasis who are candidates for phototherapy or systemic therapy. Alefacept targets the reduction of CD4+ and CD8+ memory T cells.

In the conclusion of the 111-page briefing, the FDA reviewer listed the efficacy outcomes for the patient population involved in the drug's trials. The document said the patient population is indeed representative of moderate to severe psoriasis patients, and both the intravenous and intramuscular doses were effective.

The response to treatment - meaning an improvement in PASI scores from baseline of greater than or equal to 75 percent - in the 7.5-mg intravenous group was superior to placebo, the briefing said, with an absolute difference of 11 percent. A similar response over placebo was seen in the 15-mg intramuscular group, where the absolute difference was 15 percent.

However, the FDA reviewer said it was not clear if differences in duration of response between treatment groups were clinically meaningful. Also, "there was substantial use of non-allowed antipsoriatic medications. This raised concerns about confounding of efficacy outcomes; however, the use of concomitant treatment appeared to be similar across study arms."

Regarding safety, the reviewer said there were more serious adverse events such as infections and malignancy in the groups treated with alefacept, but "the incidence of these events was too low to draw definitive conclusions." Also, "there was a suggestion of alefacept-induced hypersensitivity reaction [rare cases of urticaria] and of possible deleterious effect on healing."

The document also said studies demonstrated that "lymphocyte counts decrease and do not recover to baseline in a substantial proportion of patients even after a prolonged observation period."

The reviewer suggested that "long-term studies in larger patient populations are needed to assess the risk of infection and malignancy and the recovery of lymphocyte counts to baseline/normal."

If so, a key question will be whether Biogen would be required to conduct those studies before approval could be gained, or if the studies could be done post-approval.

The FDA panel today is expected to announce its recommendation for the drug, thus handing the reigns to the FDA, which usually, although it is not obligated to, follows the panel's suggestion.

Biogen filed for Amevive approval in the U.S. and Europe simultaneously in August using a common technical document through guidelines set in place in 2001 by the International Conference on Harmonization. If approved, Amevive would be Biogen's second marketed drug that it owns completely, the first being Avonex, approved to treat multiple sclerosis. (See BioWorld Today, August 7, 2001.)