A Phase 1, open label, repeat-dose, dose escalation study of the safety and tolerability of Staphylococcal protein A in adult patients with chronic Idiopathic Thrombocytopenic Purpura (ITP)

This study is testing the safety of a protein called PRTX-100 (derived from Staphylococcal bacteria) in adults with chronic immune thrombocytopenic purpura (ITP). ITP is a condition where the immune system destroys platelets — cells needed for blood to clot — leading to a high risk of bleeding. Multiple doses of PRTX-100 will be given at gradually increasing levels to three groups, with safety closely monitored throughout. The study is a carefully staged safety trial. You may be eligible if: - You are 18 years of age or older - You have had ITP for more than 4 months - Your platelet count is below 50 x 10^9/L (if not on steroids) or below 90 x 10^9/L (if on steroids) in the 30 days before the study You may NOT be eligible if: - You had a splenectomy (spleen removal) in the last 45 days - You have a significant heart, lung, liver, kidney, nerve, or mental health condition - You received rituximab in the last 6 months - You received other ITP treatments (cyclophosphamide, vincristine, IVIG, or anti-RhD) within 3 months (or 30 days for IVIG/anti-RhD) Talk to your doctor about whether this trial might be right for you.