An experimental drug designed to block the advancement of type 1 diabetes in its earliest stages has proven effective over a course of two years in about half of the patients who participated in the phase 2 clinical trial.

Patients who benefited most were those who still had relatively good control of their blood sugar levels and only a moderate need for insulin injections when the trial began. With the experimental drug, teplizumab, they were able to maintain their level of insulin production for the full two years, longer than with most otherdrugs tested against the disease.

Results are published online in the journal Diabetes, and will appear in the November issue of the print edition.

The treatment did not benefit all patients. Some lost half or more of their ability to produce insulin – a drop similar to many of the controls not receiving the drug.  Reasons for the different responses are unclear, but likely involve differences in the metabolic condition of the patients and in the severity of their disease at the trial’s start, the researchers said.

“The benefits of treatment among the patients who still had moderately healthy insulin production suggests that the sooner we can detect the pre-diabetes condition and get this kind of drug onboard, the more people we can protect from the progressive damage caused by an autoimmune attack,” said Jeffrey Bluestone, PhD, co-leader of the research and A.W. and Mary Clausen Distinguished Professor at UC San Francisco, who collaborated in developing the drug.

The clinical trial was led by Kevan Herold, MD, PhD, a professor of immunobiology and deputy director for translational science at Yale University. He and Bluestone have collaborated on four previous clinical trials of the experimental drug.

“We are very excited by the efficacy of the drug,” Herold said. “Some of our patients and families have described a real impact on their diabetes.”

Teplizumab is one of a number drugs under active investigation to control autoimmune reactions. The drug uses an antibody targeted against a molecule called CD3 to bind to the immune system¹s T-cells and restrain  them from attacking beta cells.

The journal’s print edition will include a commentary by Jay S. Skyler, MD, chairman of the NIH-funded Type 1 Diabetes Trial Net, an international network of researchers that also studies teplizumab for prevention of type 1 diabetes. Skyler writes that the new results make a compelling case for U.S. Food and Drug Administration approval to launch a much larger-scale, phase 3 clinical trial of the drug's effectiveness.

The study focused on 52 participants, most of whom were less than 14 years old, who had been diagnosed with “new-onset type 1 diabetes” within eight weeks of the trial’s start. All 52 were treated with the experimental drug for two weeks at diagnosis and again one year later, and their capacity to produce their own insulin to control their blood sugar was compared with a non-treated group.

Because the participants received daily insulin injections before and throughout the trial, researchers instead monitored their blood levels of C-peptide, a molecule produced in the pancreas at the same rate as insulin.