Hematopoietic Stem Cell Support Versus Insulin in T1D

Overview

Type 1 diabetes mellitus (T1D) results from immune-mediated destruction of insulin-producing islet cells. The loss of islet cells is traditionally treated with insulin therapy and in some cases pancreas or islet cell transplantation. Another approach would be to preserve islet cell mass before it is irreversibly lost. Previous trials using immune suppression within 6 weeks of T1D onset have demonstrated diminished exogenous insulin requirements compared to untreated controls. In our prior phase I non-randomized study, by extending immune suppression to the point of immune ablation / immune reset with autologous HSC support, several patients with new onset T1D have maintained an insulin-free, drug free remissions for more than 4 years. Although these results appear highly promising, it may be argued that our results are mitigated by the documented honeymoon effect following T1D, that is by a normal transient insulin free interval occurring after disease onset in some patients. The goal of this trial is to extend this phase I study of new onset T1D to clarify whether our post transplant insulin free interval is due to treatment intervention (transplant) or a result of a normally occurring "insulin free honeymoon period". Both groups will receive identical change of life style (i.e. diet, exercise) education.

Eligible patients will have type 1 diabetes (aged ≥ 18 years old) within five months of disease diagnosis, and a positive antibody to an islet cell autoantigen, and fasting C-peptide \> 0.2 nmol/l. Hematopoietic stem cells will be mobilized with cyclophosphamide (2.0 g/m2) and granulocyte colony-stimulating factor (10 g/kg/day) collected from peripheral blood by leukoapheresis and cryopreserved. HSC will injected IV after conditioning with cyclophosphamide (200 mg/kg) divided 50 mg/kg on day -5, -4, -3, -2, and rabbit antithymocyte globulin (4.5 mg/kg) divided 0.5 mg/kg day-5, and 1.0 mg/kg day -4, -3-, -2, -1. Rituxan (500mg) IV will be given on days -6 and +1. The control arm will receive either continuous subcutaneous insulin infusion (CSII) or intensive subcutaneous insulin therapy with multiple insulin injections (at least 4/day) utilizing a long acting background insulin and pre-meal rapid acting insulin. The main outcome measure will be: fasting C-peptide. Other outcome measures will include: daily exogenous insulin requirements, serum levels of hemoglobin A1c, area under the curve (AUC) C-peptide levels during mixed meal tolerance test, islet cell autoantigen antibody titers, and quality of life (QOL) short form 36 (SF-36) questionnaire.