Protalex Inc. announced preliminary findings completion of its Phase I/II open-label, single group study with former participants from its U.S.-based PRTX-100-104 Study. In this continuation study (“PRTX-100-105 Study”), rheumatoid arthritis (RA) patients received a fixed dose of PRTX-100 over a 6-month period in combination with either methotrexate or leflunomide. PRTX-100, Protalex's lead drug candidate, is a highly purified form of Staphylococcal protein A (SpA) and has been the subject of ongoing clinical development in both RA and Immune Thrombocytopenia (ITP).

PRTX-100 was recently granted Orphan Drug Designation in the U.S. and in Europe for the treatment of ITP and is currently the subject of clinical studies in both the U.S. and Europe. Eight of eleven patients in the 105 Study completed the study per protocol, which consisted of four weekly doses, followed by five monthly doses of PRTX-100 over a 6-month period at a single site in the U.S. The primary study endpoint of the 105 Study was the safety and tolerability of a fixed dose of PRTX-100 administered over an extended period. The secondary endpoints included immunogenicity, effects on measures of RA disease activity, evaluation of anti-PRTX-100 antibody presence, and feasibility of joint evaluations with ultrasound and biomarkers as disease markers.

A preliminary interim analysis indicated that for patients who completed per protocol, PRTX-100 exhibited an acceptable safety profile and RA disease activity was improved in a majority of patients at the end of the study as compared to baseline. No serious adverse events (SAEs) were reported. At study day 196, one month after the final dose, patients who completed the study per protocol demonstrated a mean reduction of the DAS28CRP score from 5.25 to 2.52, suggesting a clinically meaningful improvement in disease activity.

Additionally, clinical assessment by Ultrasound Power Doppler Joint Counts (UPD), also revealed a reduction in average disease severity by day 196, and the correlation between the UPD and the DAS28CRP was r=0.624 (p<.0005). The Company expects to submit the final clinical report to the FDA in the next several months.