Protalex Inc. announced preliminary findings from a limited interim analysis of its U.S.-based multicenter Phase 1(b) randomized, multiple-dose, dose-escalation study of PRTX-100 in combination with methotrexate or leflunomide in adults with active rheumatoid arthritis (PRTX-100-104 Study). PRTX-100 is an investigational drug incorporating a highly purified form of Staphylococcal Protein A. The interim analysis included patients in the first four dosing cohorts of the five-cohort study through day 85 of the study protocol. Five U.S. clinical centers enrolled 41 patients in Cohorts 1 through 4 of the 104 Study; five patients discontinued from the study prior to their day 85 visit.

A preliminary interim analysis of Cohorts 1 through 4 indicated that PRTX-100 was generally safe and well tolerated. The rate of adverse events (AEs) among patients receiving PRTX-100 was comparable to that of those receiving placebo and similar to that seen in prior clinical studies of PRTX-100; two patients discontinued the study because of treatment-related AEs. Pharmacokinetic analyses indicated a roughly linear increase in plasma maximum concentrations with increasing doses of 1.5, 3.0, 6.0, and 12 mcg/kg.

Effects on measures of disease activity showed that patients who received PRTX-100 had average DAS28-CRP and CDAI scores lower than the average scores of those who received placebo, which is consistent with a therapeutic effect in patients with this disease. A detailed analysis of the final 104 Study results of Cohorts 1 through 4 will be prepared for scientific presentation and publication this spring. Additionally, Protalex has completed randomization of all 20 patients into Cohort 5 of the 104 Study which is the final cohort.

These patients are receiving 5 weekly doses of PRTX-100 or placebo, followed by 4 monthly 'maintenance' doses thereafter, with total drug exposure over the six month study visit period not to exceed that of Cohort 4 (60 mcg).