RDP58, a locally active TNF inhibitor, is effective in the dextran sulphate mouse model of chronic colitis

Objective and design: RDP58 is a novel anti-inflammatory peptide that inhibits TNF synthesis and upregulates heme oxygenase-1. RDP58 therapy was evaluated in the dextran sodium sulphate (DSS) model of chronic colitis. Material: Colitis was induced by giving DSS to mice (n = 8 animals/group). Toxicity studies were done in Rhesus monkeys (n = 5), dogs (n = 3) and mice (n = 10). Treatment: In colitis, mice were treated with p. o. vehicle (saline), RDP58 (5 and 10 mg/kg/day) or 5-ASA (50 mg/ kg/day). Methods: Disease activity index (DAI) was used as the end-point of efficacy. Results: RDP58 therapy significantly reduced DAI and histological scores in all animals. DAI scores in RDP58 treated animals declined faster than 5-ASA. RDP58 at 5 or 10 mg/ kg/day significantly reduced DAI compared to 5-ASA. RDP58 significantly reduced acute, chronic and total inflammation scores. It enhanced re-epithelialization by reducing crypt scores. RDP58 was not bioavailable and was well tolerated. Conclusions: Therapeutic efficacy of RDP58 combined with a lack of bioavailibility and toxicity suggest that RDP58 may be a promising new therapeutic for IBD.