A commonly used vaccine has received FDA approval for a Phase II clinical trial to test its ability to reverse long-standing type 1 diabetes. The announcement was made at the 75th Scientific Sessions of the American Diabetes Association (ADA) by Associate Professor Denise Faustman from Massachusetts General Hospital.
The vaccine is known as bacillus Calmette-Guérin (BCG), and has been used for over 90 years as a vaccine for tuberculosis, and more recently as a treatment for bladder cancer. A 2012 pilot study in adults with long standing type 1 diabetes showed that two injections of BCG spaced 4 weeks apart temporarily reduced the number of auto-reactive killer T cells and increased the number of beneficial regulatory T cells. The vaccine was able to transiently increase the amount of c-peptide in the blood, indicating some restoration of islet function and insulin secretion.
However, there were some issues with the original study, most notably that the positive effects of the BCG vaccine on insulin production did not persist for more than one year. Additionally, the residual levels of beta-cell function that were detected were not unique to the study, having previously been seen in other patients with established type 1 diabetes, and could be achieved by agents other than the BCG vaccine.
The double-blinded, placebo controlled Phase II clinical trial will attempt to address these issues by creating a longer lasting response through more frequent dosing of the vaccine. In addition to the initial two injections, annual boosters of BCG will be given to 150 patients for five years, in the hope that more and more of the islet-destroying T cells will be eliminated, potentially allowing the pancreas to heal and regenerate. Clinical measures such as HbA1C, autoimmune reversal and stabilisation of c-peptide (a marker of islet function) will be investigated over the five years and compared with patients injected with placebo.
Even low levels of insulin production have a significant impact on long-term outcomes for people living with type 1 diabetes. If successful, this trial could enable islet function and insulin secretion to be preserved for longer, improving glycaemic control and reducing the risk of long-term complications.
For more information about the trial, click here.
To read the published Phase 1 trial, click here.