Momenta Pharmaceuticals, Inc. announced the dosing of the first subject in the Phase 1/2 clinical trial of M254, hypersialylated Immunoglobulin G (hsIgG). The Phase 1/2 study will enroll normal healthy volunteers and patients with Immune Thrombocytopenic Purpura (ITP). The multi-part study includes single and multiple dose parts, and a placebo-controlled, randomized double-blinded cross-over study comparing M254 to IVIg. The four part study will evaluate the safety, efficacy, pharmacokinetics, and pharmacodynamics of intravenous (IV) M254 in approximately 65 subjects, including healthy volunteers and patients with ITP. Parts A and B are double-blind, placebo-controlled, single ascending dose cohort studies in healthy volunteers and ITP patients, respectively. In Part C, ITP patients will receive M254 or IVIg in a cross-over dosing design, while in Part D, ITP patients will receive multiple doses of M254. The primary efficacy endpoint is an assessment of platelet response. ITP is a rare autoimmune disease that leads to excessive bruising and bleeding, which can affect children and adults, and can be acute or chronic. Abnormal autoantibodies bind to circulating platelet membranes leading to platelet destruction and subsequent reduction in the number of circulating platelets (thrombocytopenia). It is estimated that chronic ITP affects 30,000 – 60,000 patients in the U.S. Current therapies for ITP include IVIg, steroids, platelet production boosters (TPO receptor agonists) and splenectomy. Not all patients, however, have an adequate treatment response with existing therapies. As a result, there remains a significant unmet medical need for additional treatment options for patients with ITP.