2008 Update From the Collaborative Islet Transplant Registry

Background. This report summarizes the primary efficacy and the safety outcomes of islet transplantation reported to the NIDDK and JDRF funded Collaborative Islet Transplant Registry (CITR), currently the most comprehensive collection of human-to-human islet transplant data. Methods. CITR collects and monitors comprehensive data on allogeneic islet transplantation in North America, Europe, and Australia since 1999. Results. As of April 2008, the CITR registry comprised 325 adult recipients of 649 islet infusions derived from 712 donors. At 3 years post-first infusion, 23% of islet-alone recipients were insulin independent (II≥2 weeks), 29% were insulin dependent with detectable C-peptide, 26% had lost function, and 22% had missing data. Seventy percent achieved II at least once, of whom 71% were still II 1 year later and 52% at 2 years. Higher number of infusions, greater number of total islet equivalents infused, lower pretransplant HbA1c levels, processing centers related to the transplant center, and larger islet size are factors that favor the primary outcomes. Protocols with daclizumab or etanercept during induction had higher rates of II and lower rates of function loss, which endorse the current approaches. Infusion-related adverse event incidence was 0.71 events/person-year (EPY) in year 1, whereas immunosuppression-related adverse event incidence was 0.87 EPY, both declining to less than 0.21 EPY thereafter. Conclusions. Clinical islet transplantation needs to be evaluated using the most clinically relevant endpoints such as glucose stabilization and severe hypoglycemia prevention. The cumulative results of the registry confirm the inarguably positive impact of islet transplantation on metabolic control in T1 diabetes.