Islet Transplants in Type 1 Diabetes Durable Up to 8 Years

Transplantation of cadaveric pancreatic islet cells resulted in graft survival and function with acceptable safety for up to 8 years in selected individuals with type 1 diabetes, new research finds.

The study is a long-term follow-up of two phase 3 pivotal trials from the Clinical Islet Transplantation Consortium of a purified human pancreatic islet cell product for treating people with type 1 diabetes.

One trial involved islet transplantation in 48 people who experienced severe hypoglycemia and hypoglycemic unawareness, and the other trial included 24 people who also experienced those complications and were already receiving immunosuppression following kidney transplant. The trials, both registered with the US Food and Drug Administration (FDA), met their primary efficacy and safety endpoints at 2- and 3-year timepoints.

The follow-up data have now been published in Diabetes Care by Michael Rickels, MD, and colleagues.

The procedure involved infusion through the hepatic portal vein of one or more purified human pancreatic islet products under standardized immunosuppression using methods that Rickels and colleagues have been developing since 2004. The approach involves multiple modalities to protect the islets prior to transplantation.

Among the 34 islet-alone and eight islet-after-kidney transplant recipients who entered the extended follow-up, durable graft survival allowing for achievement of glycemic targets occurred without severe hypoglycemia or adverse effects from immunosuppression.

The primary outcome, actuarial survival of graft islet function, was 56% at the maximum follow-up of 8.3 years for the islet-only transplantation group and 49% at 7.3 years for the islet-after-kidney transplantation group (P = .004).

The findings suggest that “in the long run, islet transplantation has efficacy, including among those who have had kidney transplants…Most type 1 diabetes patients are improved tremendously with current insulin delivery systems…but for those having the most difficulty controlling their blood sugar — and those whose diabetes has already been complicated by needing a kidney transplant — the outcomes we saw in this study are what we’ve been hoping to achieve for more than 20 years,” said Rickels in a statement from his institution, the Perelman School of Medicine at the University of Pennsylvania in Philadelphia.

Long-Term Benefit, Safety Seen Up to 8 Years

In the initial trials at day 75 after the initial transplant, 87.5% of the islet-alone and 71% of the islet-after-kidney transplant group achieved A1c < 7%, and 85% and 54%, respectively, achieved A1c ≤ 6.5%. At the end of maximal follow-up, 49% of islet-only transplant recipients maintained A1c < 7%, although none had A1c ≤ 6.5%. For the islet-after-kidney transplant group, these proportions were 35% and 17%, respectively (P = .0017 for A1c < 7.0% and P < .0001 A1c ≤ 6.5%, respectively, between the groups).

There were 12 severe hypoglycemic episodes in five patients (three islet-alone and two islet-after kidney transplant group) during the initial trials, but no additional episodes occurred in either group during long-term follow-up.  

Overall, 53 individuals — 37 in the islet-alone and 16 islet-after-kidney transplant group — or 74% of the total, achieved a period of insulin independence with A1c < 7%, ranging from 36 to 481 days. The range of time to achieving insulin independence reflects individuals who received one, two, or three islet infusions.

The fact that most patients achieved insulin independence following just one (n = 20) or two (n = 30) infusions and only three patients required three infusions was notable, Rickels said.

“Currently, around the world, there’s an expectation of two-to-three donor pancreases being needed. Here, it’s one, maybe two. It’s a much more efficient protocol and opens up access for more islet transplantation as a hoped-for alternative to pancreas transplants.”

Of those who achieved insulin independence, 30 (57%) remained insulin-independent throughout follow-up (20 of 37 islet-alone and 10 of 16 islet-after-kidney transplant patients), with no difference in duration of insulin independence between the groups.

There were no deaths during post-transplant follow-up. Rates of serious adverse events were 0.31 and 0.43 per patient-year for the islet-after-kidney and islet-alone transplant groups, respectively. Of a total of 104 serious adverse events, 65 occurred during the initial trials and had been previously reported. Of the additional 39 serious adverse events that occurred during long-term follow-up, 11 were possibly due to immunosuppression and 27 were deemed unrelated to the procedures.

According to Rickels, “These are the most seriously affected patients, and you’d be expecting to see some hospitalizations in a population managed on immunosuppression therapy…It’s important to note that none of the adverse events were related to the actual islet product. Also, kidney function remained stable during long-term follow-up in both cohorts, in fact, improving in those who had kidney transplants.”

Overall, he said, “This is a much less invasive procedure that opens itself up to significantly fewer complications than what many of these patients would otherwise require, a pancreas transplant, which involves major abdominal surgery.”

The investigators plan to submit these data as part of a biologic license application (BLA) to the FDA.

The research was supported by grants from JDRF, the National Institute of Diabetes and Digestive and Kidney Diseases, and the National Institute of Allergy and Infectious Diseases. Rickels has reported receiving consulting fees from Sernova Corp and Vertex Pharmaceuticals.

Diabetes Care. Published online October 17, 2022. Abstract

Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape, with other work appearing in The Washington Post, NPR’s Shots blog, and Diabetes Forecast magazine. She is on Twitter: @MiriamETucker.

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