New study highlights the challenges of translating promising research to effective treatments

Results from a clinical study in people with type 1 diabetes (T1D) who were treated with a combination of two drugs in an attempt to improve their beta cell survival and stimulate beta cell regeneration are so far inconclusive. The study, called REPAIR-T1D and supported by JDRF and Sanford Health, tested the effect of the heartburn drug lansoprazole and the type 2 diabetes drug sitagliptin on preserving remaining beta cell function as measured by C-peptide levels in sixty-eight people recently diagnosed with T1D. The results, recently published in the journal The Lancet Diabetes & Endocrinology, showed that the average C-peptide levels of the forty-six people treated with the combination therapy continued to decline and were no different than the twenty-two placebo-treated individuals over a 12-month timeframe.

However, the study results did suggest a possible small benefit of this combination drug therapy in some people. In a subgroup of participants who had higher levels of a specific hormone induced by one of the drugs, C-peptide levels were more stable during the study. This may indicate that some people in the study who did not receive any benefit from the therapy needed higher doses of the drugs to work as intended. If substantiated, this finding could be an important learning from the study.

The REPAIR-T1D study was started more than 2 years ago based on promising results treating diabetic mice with the same drug combination. In these animals and in mice with transplanted human islets, the drug combination increased their beta cell numbers and restored them to normal glucose control. The reason for the general lack of efficacy in people in this study is not clearly understood, and it is not the first time results in mice did not translate directly to people. This emphasizes the need for more focus on conducting well-designed pilot human studies of promising T1D therapies and better markers of an effect to shorten study durations.

The REPAIR-T1D study participants will be followed for another 12 months to more fully evaluate the therapy and gain further insights that may point to ways to improve testing this therapy in a future study.

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