Repligen Corporation, a biopharmaceutical company, announced that its Phase 3 clinical trial in autism of RG1068, synthetic human secretin, failed to meet the study's dual primary endpoints, improvements in social interaction as measured by the Autism Diagnostic Observation Schedule (ADOS) and the parental Clinical Global Impression of Change (CGI). The Phase 3 study had a higher placebo effect than was observed in the Phase 2 study and neither endpoint showed a significant treatment effect in the entire group. A prospectively defined subset analysis of the higher functioning patients (n=68) showed a statistically significant improvement of RG1068 versus placebo on ADOS but not on the CGI. This finding may indicate that measuring a response to RG1068 is more difficult in patients with lower levels of cognitive function.

A preliminary review of the safety data showed no clinically meaningful differences between RG1068 and placebo in side effects and there were no serious adverse events observed in the Phase 3 trial.

This trial evaluated 132 children aged 2 years 8 months to 4 years 11 months with moderate to severe symptoms of autism. Each patient was evaluated at baseline, received six injections of RG1068 or a placebo over 18 weeks and was then reevaluated for improvements. The primary endpoints were improvements in reciprocal social interaction as measured by ADOS, which is performed by a trained psychologist, and the parental CGI.

Walter Herlihy, president and CEO of Repligen, stated, "We have developed an extensive preclinical and clinical data set which supports the use of secretin in the treatment of other neuropsychiatric diseases and we plan to continue our efforts to develop secretin for schizophrenia."

Repligen is currently conducting a Phase 2, double-blind, placebo-controlled, clinical trial to evaluate RG1068 in patients with refractory schizophrenia.