Safety and efficacy of Gammaplex® in idiopathic thrombocytopenic purpura (ClinicalTrials.gov--NCT00504075)

Abstract

Background and objectives: This multicentre, open-label study investigated the safety and efficacy of Gammaplex, a 5% Intravenous Immunoglobulin (IVIg), in patients with idiopathic (immune) thrombocytopenic purpura (ITP).

Materials and methods: Patients were between the ages of 6 and 70 years; had ITP for at least six months and had a platelet count ≤ 20 × 10(9)/L. Eligible patients were dosed with 1 g/kg of Gammaplex on two consecutive days, followed by assessment of safety and efficacy on Days 3, 5, 9, 14, 21, 32 and 90. Response was defined as the increase in platelet count to a threshold of ≥ 50 × 10(9)/L on or before Day 9 after the first dose of Gammaplex.

Results: All 35 patients received at least one infusion of Gammaplex. Twenty-nine (83%) patients responded to Gammaplex, similar to the historical control, with a 95% lower one-sided confidence interval of 68.9%. Median duration of response was 10.0 days, with an overall reduction in bleeding episodes. Gammaplex provided supranormal concentrations of total IgG; mean peak concentration (Cmax) of 45.3 g/L (4.53 g/dL), with a mean half-life of 28.5 days. Fifteen patients reported 63 Adverse Drug Reactions (ADRs); the most common were headache (10 patients), vomiting (6 patients) and pyrexia (5 patients). Five of these ADRs were considered serious, one patient had three concurrent Serious Adverse Events (SAEs); these were vomiting, dehydration and headache. Two other patients each had one SAE (headache). There were no unexpected Adverse Events (AEs) or thromboembolic episodes and no significant changes in vital signs, biochemical, haematological and virology results.

Conclusion: Gammaplex achieved a very high concentration of serum IgG but was well-tolerated and effective in the treatment of ITP with a similar degree of efficacy to the pre-determined historical control group and the pre-set statistical criteria.

Trial registration: ClinicalTrials.gov NCT00504075 Clinical Trials Registry India 000016.

Conflict of interest statement

Competing Interests: At the time of publication the authors K.R. Gillanders and E.W. Gascoigne were employees of BPL. The authors C.H. Dash, S.J. Leach and M.E Stratford Bobbitt were contracted by BPL. C.H. Dash, K.R. Gillanders, S.J. Leach and M.E. Stratford Bobbitt were involved in the management of the trial. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.

Figures

Figure 1. Flow diagram for patients enrolled.

Figure 2. Median platelet count from baseline to Day 32 after Gammaplex infusions.

Figure 3. Bleeding/haemorrhage reports from screening to Day 32.