Abbott Laboratories (ABBOTT PARK, Illinois) announced positive study data from an extension to a phase II study demonstrating that a majority of moderate-to-severe psoriasis patients who responded to anti-IL-12/23 (ABT-874) after 12 weeks of treatment maintained a high level of response at 24 weeks, following discontinuation of therapy. In the double-blind, placebo-controlled phase II study, patients who achieved 75% improvement in psoriasis signs and symptoms (PASI 75) at 12 weeks stopped receiving ABT-874. At 24 weeks, results showed that substantial percentages of PASI 75 responders in the active treatments arms maintained >e; PASI 50 responses. Results were 68% (13 out of 19 patients), 71% (20 of 28), 81% (22 of 27), 89% (25 of 28), and 85% (23 of 27) in the five ABT-874 dosing groups, respectively.

The study comprised 180 patients who were randomized evenly to six treatment groups: a single, subcutaneous 200-mg injection of ABT-874 at week 0; 100 mg every other week (eow) for 12 weeks; 200 mg weekly for 4 weeks; 200 mg eow for 12 weeks; 200 mg weekly for 12 weeks; or matching placebo. The primary study endpoint was the proportion of patients achieving 75% PASI improvement in the degree and severity of skin lesions after 12 weeks. Results from this study reported earlier this year showed ABT-874 significantly reduced psoriasis symptoms in the majority of patients treated. Also, more than half of patients achieved 90% improvement in the same four of five ABT-874 dosing groups, versus 0% improvement in those receiving placebo.

In the phase II continuation study, treatment with ABT-874 was discontinued in patients who met the primary endpoint. Maintenance of PASI response was evaluated through week 48.

ABT-874 is a fully human monoclonal antibody designed to target and neutralize interleukin-12 and interleukin-23, two proteins associated with inflammation in psoriasis and other autoimmune disorders. Abbott plans to begin phase III psoriasis studies with ABT-874 later in 2007.