Phase 2 clinical trial evaluating the benefits of a vaccine for patients newly diagnosed with type 1 diabetes mellitus

This study evaluated the efficacy and safety of the glutamic acid decarboxylase (GAD) vaccine for the treatment of newly diagnosed patients with type 1 diabetes mellitus (T1DM). 

T1DM results from an autoimmune (an immune response against the body's own cells and tissues) destruction of insulin-producing cells of the pancreas. Insulin is needed for the body to use glucose (a type of sugar) as energy. The lack of insulin in T1DM leads to a glucose build-up in the blood stream. These patients usually need life-long treatment with insulin injections. Along with insulin, the pancreas also produces equal amounts of a protein called the C-peptide. By measuring the levels of this protein, the doctor can determine the real amount of insulin produced by the pancreas, as a way of differentiate it from the insulin injected into the body. Glutamic acid decarboxylase (GAD) is an enzyme (a type of protein) that has been associated as a target of the autoimmune process in T1DM. Recent studies have shown that treatment with GAD in newly diagnosed patients with T1DM may preserve the function of the insulin-producing cells of the pancreas, thus preserving insulin secretion and slowing down the course of the disease.

The phase 2 clinical trial included 145 patients who had been diagnosed with T1DM for less than 100 days. Patients were randomly assigned to receive for one year either the GAD vaccine (2 or 3 injections) or a placebo (a substance with no medical effect, used as a control in testing new drugs). The main parameters evaluated were blood sugar control and the dose of insulin patients needed, as well as side effects for the treatments.

After 1 year of treatment, the levels of the C-peptide (thus, the insulin production) had a 44% decrease in patients who received 3 injections of GAD vaccine, 42% decrease with 2 injections of GAD vaccine and 41% decrease with placebo. Further, blood sugar and insulin dose needed by patients gradually increased over time. The treatment was safe and well tolerated by all patients, with no significant side effects reported.

In summary, the study found that the treatment with two or three injections of GAD did not affect the course of loss of insulin production over one year.

This study had a small number of participants. Future studies on larger numbers of patients are needed in order to further evaluate the effects of GAD vaccines in patients with T1DM.