Long-term safety and efficacy results of the Edmonton Protocol for islet transplantation were reported October 3, 2015 in the American Journal of Transplantation. Data from the Immune Tolerance Network’s (ITN) EXIIST Study (Extended Immunosuppression in Islet Transplantation), led by Dr. Daniel Brennan (Washington University), demonstrate that islet transplantation with steroid-free immunosuppression over a 10 year period enables good islet graft function and glucose control without serious adverse events or infections.
The EXIIST study was initiated in 2010 to provide continued access to immunosuppressive medications for patients enrolled in a prior multi-center islet transplant study (NIS01/ITN005CT). Islet transplantation is still considered experimental for treating type 1 diabetes and therefore immunosuppressive medications are not covered by health insurers. The extended study also allowed for the assessment of long-term safety and islet allograft function with prolonged use of immunosuppression.
Of the 36 participants that participated in the first study, 7 were eligible and consented to enroll in EXIIST. Islet function was assessed using C-peptide responses to a mixed meal tolerance text (MMTT). All 7 participants in EXIIST maintained allograft function for at least 10 years and achieved insulin independence for periods ranging from 5 to 126 months (median 56 months). Two participants remained insulin-independent at the last study visit, and for those who lost insulin-independence, insulin usage was still significantly less than before the transplant. Although there was a gradual decline in participants’ insulin production over the course of the study, overall glucose control was relatively stable. Also, despite the extended use of immunosuppression, there were no serious infections throughout the course of the study.
This is the first prospective, multicenter study to demonstrate that the long-term use of immunosuppressive medications for 10 years following islet transplantation is associated with durable islet allograft function and good safety. Islet transplantation protocols have continued to improve since the initiation of this study and may lead to better outcomes and longer periods of insulin-independence.