SAFETY OF CDP870, A PEGYLATED HUMANIZED ANTI-TNF ANTIBODY FRAGMENT, IN CROHN’S DISEASE Stefan Schreiber, M.D.*, Trevor Winter, M.D., Alison Innes, Jatin Patel, the CDP870 Crohn’s Disease Study Group. Christian-Albrechts University, Kiel, Germany; University of Kentucky, Lexington, KY and Celltech Research and Development, Slough, United Kingdom. Purpose: We reported that CDP870 is effective for treatment of Crohn’s disease (CD). The safety and pharmacokinetics of CDP870 have been investigated in 2 Phase II studies in CD. Methods: Two trials were analyzed: 292 adult patients with active CD (CDAI score 220–450) received subcutaneous (sc) administration of CDP870 100 (n 74), 200 (n 72) or 400mg (n 73), or placebo (n 73) at wks 0, 4, and 8. In a second study, adult patients with active CD received a single intravenous (iv) infusion of CDP870 1.25 (n 2), 5 (n 26), 10 (n 17) or 20mg/kg (n 23), or placebo (n 24). Adverse events (AEs) were monitored up to wk 20 in the sc study and up to wk 12 in the iv study. Plasma concentrations of CDP870 were assessed serially. Results: The incidence and pattern of AEs in both studies were comparable across treatment groups and the majority of events were of mild–moderate intensity. The most frequent AEs included headache, aggravated CD, nausea and nasopharyngitis. The most frequently occurring infections among CDP870-treated patients were nasopharyngitis, urinary tract infection and influenza. There was no increase in opportunistic infections and no tuberculosis. There were no deaths, lupus or malignancy. Of the patients who received sc CDP870, 13.7% (30/219) experienced serious AEs vs 21.9% (16/73) of the placebo group, and 10.5% (23/219) of patients withdrew due to AEs. In the iv study, 10.3% (7/68) of CDP870-treated patients and 8.3% (2/24) of the placebo group experienced serious AEs. 2 patients given iv infusions of CDP870 withdrew due to AEs. Of the patients in th sc study 78.1% (228/292) received all 3 injections. A low incidence of mild–moderate injection site reactions was reported: 2 (2.7%), 5 (6.8%), 4 (5.6%) and 2 (2.7%) in the placebo and 100, 200 and 400mg CDP870 treatment groups, respectively. None resulted in withdrawal. No CDP870related infusion reactions were reported in the iv study. Following sc and iv administration, CDP870 mean maximal plasma concentrations were broadly dose-proportional. Pharmacokinetic profiles were consistent with a half-life of approximately 2 wks. Conclusions: Safety experience to date in 287 patients with CD suggests that sc and iv administration of CDP870 is well tolerated and that CDP870 has favorable tolerability compared with other biologics against TNF.