A Safety Study of Intravenous Immunoglobulin in Patients With Chronic Immune Thrombocytopenic Purpura (ITP)

A Safety Study of Intravenous Immunoglobulin in Patients With Chronic Immune Thrombocytopenic Purpura (ITP)

An Open-label, Prospective, Multicenter Study to Investigate the Specificity of in Vivo Antibody Binding to Red Blood Cells in Subjects With Chronic Immune Thrombocytopenic Purpura (ITP) Treated With IgPro10 (Privigen®) Who Have Shown Signs of Hemolysis

It is known that intravenous immunoglobulins can induce hemolysis, but the mechanism is not known in detail. The primary objective of this study was to investigate the specificity of antigens on red blood cells in patients with chronic immune thrombocytopenic purpura (ITP) who have shown signs of clinically relevant hemolysis following treatment with the intravenous immunoglobin Privigen®. The study was to explore potential mechanisms of hemolysis by analysis of the specificity of the antibodies possibly involved. To distinguish between clinically non-relevant hemolysis and a relevant intravascular hemolysis, an independent adjudication by a committee was performed for each patient with signs of hemolysis determined in the laboratory or in the clinic. This study was requested as a post-marketing commitment study by the United States Food and Drug Administration (FDA). By September 2014, no case of clinically significant intravascular hemolysis was found, and the FDA agreed to halt the study and analyze all hemolysis-relevant endpoints using FDA criteria for hemolysis in addition to analyses planned in the protocol. The study was not restarted.

IgPro10 will be administrated by IV infusion either a single dose of 1 g/kg bw on 1 day or 2 doses of 1 g/kg bw on 2 days (2 g/kg bw total dose) dependent on the response to the first treatment.

Set of Antibodies Most Frequently Bound to Red Blood Cells (RBCs) in Subjects Experiencing Clinically Significant Intravascular Hemolysis

The occurrence of clinically significant intravascular hemolysis was determined by an independent Adjudication Committee. No subject experienced clinically significant intravascular hemolysis; therefore, the primary safety endpoint could not be analyzed.

The responder rate is the percentage of subjects who have a platelet response (defined as a platelet count increase at least once to ≥ 50 x 10^9/L after the first IgPro10 administration).

Inclusion Criteria: Diagnosis of chronic ITP Age of 18 to 65 years Platelet count of ≤ 30 x 10^9/L at screening Exclusion Criteria: Planned splenectomy throughout the study period Treatment with immunoglobulin G for intravenous administration (IVIG) or anti-D immunoglobulin within 3 weeks prior to screening Use of drugs that have any pharmacological effect on the blood clotting system within 3 weeks prior to screening Known allergy or other severe reactions to blood products including intolerability to previous IVIG Known hyperprolinemia Red blood cell transfusion or erythropoietin treatment within the last 14 days