GlaxoSmithKline and partners have suffered a setback after the type 1 diabetes investigational drug otelixizumab failed in a late-stage clinical trial.

GSK and US biotech Tolerx have announced that the 272-patient Phase III DEFEND-1 study of otelixizumab, a humanised anti-CD3 monoclonal antibody, did not meet the primary efficacy endpoint of change in C-peptide (which measures the function of insulin-producing beta cells in the pancreas) at month 12 in patients with new-onset autoimmune type 1 diabetes. GSK says it will continue to explore additional dosing regimens "to inform decisions about the future clinical development programme for otelixizumab".

The UK drugs major added that new recruitment and dosing in the DEFEND-2 study, the ongoing confirmatory Phase III study with a design similar to DEFEND-1, has been suspended pending review of the latter's results. Jackie Parkin, medicines development leader at GSK, said that "clearly these are disappointing data, but we are committed to working with Tolerx to better understand the results of this study and determine the way forward".

The failure also represents a bit of a blow to BTG, the London-headquartered firm which licensed otelixizumab to Tolerx in 2007. Chief executive Louise Makin said that the result of the DEFEND-1 study "is obviously disappointing, though we note that GSK is continuing development of otelixizumab in autoimmune diseases".

BTG's share price did not suffer and analysts do not ascribe much value in their models to otelixizumab. The firm's future fortunes are more closely linked to three partnered last-stage assets, namely abiraterone acetate for advanced prostate cancer (Johnson & Johnson), alemtuzumab in multiple sclerosis (Genzyme Corp) and AZD9773 (AstraZeneca) for severe sepsis.