A Trial to Treat Patients With ITP Who Do Not Achieve a Durable Response to Rituxan Alone

Inclusion Criteria: Patients will be eligible to participate in the study if they: * Have chronic ITP19 (\> 6 months duration). * Have received Rituximab a minimum of 3 months prior to entry. * Have received no more than 2 courses of Rituximab at standard dose separated by a minimum of 12 weeks. * Have not achieved a durable response to Rituximab, with platelet counts \< 30,000/ml when not supported by other treatment. * Have a platelet count of \< 30,000/ul on two separate occasions 1-2 weeks apart within the past month prior to the inclusion. * Are age ≥ 12 years old. * Had a splenectomy at least 60 days prior to study entry, or a contraindication to splenectomy. * Give written informed consent. * Use an effective means of contraception during treatment and for six months after completion of treatment. * Have negative serum pregnancy test, for all women who are able to have children, within 14 days prior to study entry. Exclusion Criteria: Male and female subjects will be ineligible to participate if they: * Received prior treatment with cyclophosphamide within the last 3 months. * Received prior treatment with \> 4 infusions of vinca alkaloids within the 6 months. * Had previous or concomitant malignancy other than basal cell or squamous cell carcinoma of the skin, carcinoma-in-situ of the cervix, or other malignancy for which the patient had not been disease-free for at least 5 years. * Have an HIV infection. * Have hepatitis Bs antigen positivity or active hepatitis C infection * Have an absolute neutrophil count \< 1.000/mm3 at study entry (unless related to autoimmune neutropenia). * Have a Hemoglobin level \< 10 g/dl other than caused by thalassemia trait, iron deficiency or autoimmune hemolytic anemia (patients with Evan's syndrome will not be excluded). * Have an impaired renal function as indicated by a serum creatinine level \> 2.0 mg/dL. * Have an inadequate liver function as indicated by a total bilirubin level \> 2.0 mg/dL and/or an AST or ALT level \> 3x upper limit of normal. * Have active infection requiring antibiotic therapy within 7 days prior to study entry. * Are pregnant or lactating women, or plan to become pregnant or impregnated within 12 months of receiving study drug. * Have had a prior severe reaction to Rituximab, leading to discontinuation of treatment. * Have a New York Heart Classification III or IV heart disease. * Have a history of severe psychiatric disorder or are unable to comply with study and follow-up procedures.