The US Food and Drug Administration (FDA) has approved a phase II clinical trial for testing the ability of a promising vaccine to reverse advanced Type-1 diabetes, researchers said.

The generic vaccine called Bacillus Calmette-Guerin (BCG) was earlier found effective in reversing advanced Type-1 diabetes in mice and subsequently completed a successful phase I human clinical trial.

The five-year trial will investigate whether repeat BCG vaccination can clinically improve Type-1 diabetes in adults between 18 and 60 years of age who have small but still detectable levels of insulin secretion from the pancreas.

“In the phase I clinical trial we demonstrated a statistically significant response to BCG, but our goal in phase II is to create a lasting therapeutic response,” said principal investigator of the study Denise Faustman, director of the Massachusetts General Hospital (MGH) immunobiology laboratory.

“We will be working again with people who have had type-1 diabetes for many years. This is not a prevention trial; instead, we are trying to create a regimen that will treat even advanced disease.”

A generic drug with over 90 years of clinical use and safety data, BCG is currently approved by the FDA for vaccination against tuberculosis and for the treatment of bladder cancer.

The vaccine is known to elevate levels of the immune modulator tumor necrosis factor (TNF), which Faustman’s team previously showed can temporarily eliminate in both humans and mice the abnormal white blood cells responsible for autoimmune Type-1 diabetes.

In the new trial, which will be double conducted at MGH, 150 adults with long-term Type-1 diabetes will be randomised to receive two injections four weeks apart of either BCG or placebo and then a single injection annually for the next four years.

Faustman announced the approval of the trial at the 75th scientific sessions of the American Diabetes Association (ADA) in Boston, Massachusetts on June 7.