Idera Pharmaceuticals (NASDAQ: IDRA) today announced that 48% of patients with moderate-to-severe plaque psoriasis (12 of 25) treated with IMO-3100, a selective antagonist of Toll-like Receptors (TLRs) 7 and 9, demonstrated improvements in Psoriasis Area Severity Index (PASI) scores of 35% to 90% from baseline at the completion of a randomized, double-blind, placebo-controlled Phase 2a clinical trial of two dose levels of IMO-3100 administered for four weeks, with a four-week follow-up period. None of the 12 placebo-treated patients had improvement in this range; this difference was statistically significant (p<0.005). The Company believes the results of this trial provide clinical proof-of-concept for the mechanism of action of selective TLR inhibition in patients with psoriasis and potentially other autoimmune and inflammatory disorders. “The clinical activity of IMO-3100 demonstrated in patients with moderate-to-severe plaque psoriasis is encouraging, especially given the short duration of treatment in this study that was designed for initial explorations of safety and efficacy,” commented Alexa Kimball, M.D., M.P.H., Vice Chair, Department of Dermatology at Massachusetts General Hospital, Boston, and an investigator in the trial. “The achievement of statistically significant PASI reductions with only four weeks of treatment in a placebo-controlled double-blind trial directly supports the rationale that the modulation of specific TLRs plays a key role in the treatment of psoriasis and, potentially, other autoimmune and inflammatory disorders,” commented James Krueger, M.D., Ph.D., of The Rockefeller University, New York. “We are excited to see these data, which demonstrate the translation of targeting a novel mechanism of action into clinical activity and support further studies of TLR antagonists for the treatment of psoriasis. Our laboratory is continuing to evaluate the immunological pathways by which TLR antagonists suppress the signaling cascades that underlie psoriasis and have the potential to open up a new approach to disease treatment.” About the IMO-3100 Phase 2 Trial in Psoriasis The Phase 2 trial was a randomized, double-blind, placebo-controlled trial of IMO-3100 in patients with moderate-to-severe plaque psoriasis. In the trial, 44 patients were randomized to receive IMO-3100 monotherapy at 0.16 or 0.32 mg/kg or placebo by subcutaneous injection once weekly for four weeks with four weeks of follow-up. Assessments of safety were performed throughout the treatment and follow-up periods. Multiple parameters were monitored to assess the clinical activity of IMO-3100, including Psoriasis Area Severity Index (PASI), mean focal psoriasis severity and Physician Global Assessment (PGA) scores. In addition to the clinical assessments, biopsies of psoriasis plaques were evaluated for treatment-related changes in epidermal thickness and immune cell infiltrates consistent with the intended mechanism of action. Patients were enrolled at eleven sites in the United States.