A study conducted at Diabetes Research Institute at University of Miami Millar School of Medicine, FL, USA for assessing the effectiveness of a vaccine for type 1 diabetes has not met with success. The study was presented at the American Diabetes Association meeting in San Diego, and was also published in The Lancet. The lead clinical investigator for the study is Dr. Jay Skyler.
The most pressing challenge for any successful diabetes vaccine is to selectively protect the insulin producing beta cells from auto-immune attack while at the same time not interfere with the immune system in an adverse way so that it leads to altered or lowered immunity. Based upon studies conducted prior to this report, there has been accumulating evidence that glutamic acid decarboxylase (GAD) is an appropriate target antigen for type 2 diabetes.
The authors in this study wanted to test the hypothesis that repeated injections of 20 μg GAD formulated with the adjuvant alum (GAD-alum) in type 1 diabetes patients who had been diagnosed for less than three months would lead to a preservation of insulin secretion as measured by production of C-peptide levels. C-peptide levels are a direct indicator of the level of insulin production and thus beta cell function.
This study enrolled 145 patients ranging from 3-45 years who had been diagnosed with type 1diabetes for 100 days or less. In total, 15 sites from USA and Canada participated in this study. The study was designed in a way so that these patients could be randomized to any of the three arms of the study: three injections of 20 μg GAD-alum, two injections of GAD-alum and one of alum, or 3 injections of alum (as a control group).
Data that has emerged from this study has revealed that in all three groups, there was a similar decline in beta cell function, as depicted by their respective measured C-peptide levels. This led the researchers to conclude that there was no difference in the progression of type 1 diabetes in all three groups.
While the researchers confirmed that the GAD vaccine was ineffective in patients who had been diagnosed recently, the vaccine may still have a role to play in preventing type 1diabetes if instituted earlier during the natural progression of this disease. They also claimed that GAD vaccine could become an adjunct treatment in a combination therapy therapeutic regimen provided to recent-onset type 1 diabetes patients. The authors pressed for an increased requirement for research to ascertain the effectiveness of GAD vaccine if given earlier or as a part of a standard therapeutic regimen in patients with type 2 diabetes.
In a comment that is linked to this study report, Dr. Chantal Mathieu and Dr. Pieter Gillard at the University Hospital Leuven, Catholic University of Leuven, Leuven, Belgium stated that there was consensus among experts that combination therapy that combined immune modulating drugs or interventions (perhaps including anti-CD3) at lower doses along with an antigen specific strategy was the solution for type 1 diabetes.
They concluded that researchers should continue their research in this important disease area and not give up hope of preventing or curing type 1 diabetes. They pressed for a continued interest of pharmaceutical companies, scientific community and other agencies so that type 1 diabetes can be beaten. They stated that there was no dearth of ideas, motivation as well as machinery to perform the complex studies required to accomplish this research.
Written by Barry Windsor