Protalex Inc. announced dosing of the first patient in its European Phase Ib study of PRTX-100 in adults with persistent/chronic Immune Thrombocytopenia (ITP) (the PRTX-100-203 Study). PRTX-100, Protalex's lead drug candidate, is a highly purified form of Staphylococcal protein A (SpA), which was granted Orphan Drug Designation in Europe and the U.S. for the treatment of ITP. A similar Phase I/II clinical study of PRTX-100 is underway in the U.S. (the PRTX-100-202 Study).

PRTX-100 is also the subject of ongoing clinical development in Rheumatoid Arthritis (RA). The 203 Study is an open-label, dose-escalation study that will enroll up to 30 patients in as many as five cohorts at five to six clinical centers in France. Each patient will receive four weekly intravenous doses of PRTX-100 and will be monitored for up to 48 weeks thereafter.

The primary study endpoint of the 203 Study is safety. Secondary endpoints include platelet response, immunogenicity and pharmacokinetics.