Omeros Corporation (OMER) has released additional positive results from its Phase I trial of its drug candidate OMS824, the lead compound in its phosphodiesterase 10 (PDE10) programme, for the treatment of cognitive disorders.

In the trial, the company assessed the extent to which OMS824, at a dose higher than previously reported, binds to PDE10, an enzyme expressed in the region of the brain that has been linked to a range of diseases that affect cognition.

The trial showed that OMS824 achieved an average of 63% engagement at PDE10 and did not generate the dose-limiting side effects seen with other PDE10 inhibitors.

In addition, the data helps further development of the drug through clinical trials in cognitive disorders patients.

The company has already started Phase II trial last month to assess the drug in patients with schizophrenia and intends to begin a Phase II trial in Huntington’s disease later in 2013.

The Phase I trial was carried out in healthy male subjects given OMS824 once-daily for seven days at a dose higher compared with those previously assessed in the target-engagement clinical trial.

"We look forward to reviewing the series of data from our ongoing programmes in patients suffering from Huntington’s disease and schizophrenia."

During the trial, positron emission tomography (PET) scans were used to measure the binding activity of OMS824 to PDE10 in the brain and the drug was well tolerated with mild somnolence as the only apparent side effect.

Omeros chairman and chief executive officer Gregory Demopulos said: "We look forward to reviewing the series of data from our ongoing programmes in patients suffering from Huntington’s disease and schizophrenia."

In the PET trial, the level of target engagement is seen to be significantly higher with lesser side effects.

Compared with the PET trial, the recently completed Phase I clinical pharmacokinetic trial with 10 days of OMS824 dosing achieved about 50% higher plasma concentrations with mild, well-tolerated and self-limiting side effects.

The company said PET data was not secured in the pharmacokinetic trial but based on modelling of all data obtained in the OMS824 Phase I trial, it is estimated that the drug engaged the PDE10 enzyme at levels substantially more than 63%.

In order to confirm this estimate, the company is currently planning to assess a higher dose of OMS824 in the PET trial.

Omeros’ PDE10 programme focuses on an enzyme that is expressed in areas of the brain linked to diseases that affect cognition and psychomotor functions, including Huntington’s disease and schizophrenia.

According to the company, OMS824 has the potential to improve the motor and psychiatric abnormalities in Huntington’s disease, as well as the positive and negative symptoms of schizophrenia apart from its potential benefits on cognition.

Omeros recently received orphan drug designation from the US FDA to evaluate OMS824 in Huntington’s disease while its fast-track application to the FDA is currently under review.