Patient Inclusion Criteria

Patients must be willing and able to give written informed consent by signing an IRB-approved Informed Consent Form prior to admission to this study. Patients may be male or female, between the ages of 18 75. Men, if sexually active, must agree to use at least one medically acceptable form of birth control. Women of childbearing potential must have a negative urine pregnancy test, and agree to use two independent methods of birth control, if sexually active. Patients must have a diagnosis of chronic refractory ITP for at least 3 months. Chronic refractory ITP is defined as: 1. Platelet count less than 30,000/mm3 consistently for 3 months (except for transient nonsustained responses to various therapeutic regimens). There must be at least three separate platelet counts (below 30,000/mm3) over this period, with at least one extending back to three months or more prior to patient entry into the study. 2. The following conditions will have been excluded either by history or appropriate laboratory investigation: HIV infection (see below), lymphoproliferative disorders, myelodysplasia, SLE, drug-induced or alloimmune thrombocytopenia, or dysglobulinemias. 3. The patient must have tried at least two typical regimens for the treatment of ITP (George et al., Blood, 1996; Practice Guidelines, American Society of Hematology). At least 50% of the enrolled patients will not be known to be refractory to IVIg. Patients may or may not have been treated with IVIg in the past. Subjects must test negative for HIV, HBV, and HCV by standard serologic tests within the previous six months.

Patient Exclusion Criteria

Patients who have a history or presence of substantial or clinically significant respiratory, gastrointestinal, renal, hepatic, neurological, cardiovascular, psychiatric, musculoskeletal, genitourinary, dermatological, or other disorders that, in the Investigator's opinion, could affect the conduct of the study or the absorption, metabolism or excretion of the study drug are excluded. Specifically excluded are lymphoma/chronic lymphocytic leukemia, hepatitis, or HIV associated with ITP. - Patients who have a history of relevant drug hypersensitivity are excluded. - Patients who have a history of substance abuse, drug addiction or alcoholism are excluded. Patients with the following laboratory abnormalities: a leukocyte count less than 2,500/mm3, a neutrophil count of less than 1,800/mm3, lymphocyte count less than 750/mm3, Hgb less than 10 g/L, or transaminase levels (ALT, AST) greater than 1.5xULN are excluded.