US-based clinical-stage biopharmaceutical firm Omeros has dosed the first patient in a second Phase II clinical trial of its phosphodiesterase 10 (PDE10) inhibitor OMS824, being developed for the treatment of schizophrenia, Huntington's disease (HD) and other cognitive disorders.
The Phase II study is designed to assess the tolerability, safety, pharmacokinetics and performance on a battery of tests in patients with symptomatic HD.
Around 120 patients with Huntington's disease will be enrolled in the second Phase II trial and they will be randomised to receive placebo or one of three doses of OMS824.
The dose levels were selected based on tolerability and PDE10 target occupancy results in Phase I studies carried out in healthy patients.
According to the company, the doses assessed in the second Phase II trial are expected to be well tolerated and cover a range of PDE10 target occupancy in the brain.
Efficacy will be evaluated across three functional domains that are affected by the disease: motor, cognitive, and behavior.
In the trial, patients are allowed to continue their usual medications based on the results of the earlier Phase II trial in which schizophrenia patients who took similar classes of drugs had no untoward interactions with OMS824.
Interim results are expected in the second half of 2014 with final data scheduled to be available in 2015.
In the US, HD is estimated to affect around 31,000 patients and the only drug approved by the US Food and Drug Administration (FDA) for the treatment of this disease is tetrabenazine, which is indicated for Huntington's-related movement disorders.
The company said that OMS824 has the potential to improve the cognitive and psychiatric abnormalities and also the movement disorders related with the disease.
Omeros previously secured FDA Orphan Drug designation to assess OMS824 in HD and FDA Fast Track designation for the development of OMS824 to treat cognitive impairment in HD.
About 70% engagement at PDE10 was achieved in the positron emission tomography (PET) trial following dosing with OMS824 without evidence of extrapyramidal symptoms (EPS), the company said.
According to Omeros, OMS824 achieves greater PDE10 target occupancy without EPS than does any other PDE10 inhibitor previously or currently in development.
Omeros also intends to evaluate a higher dose of OMS824 in the PET trial to determine whether an even higher level of PDE10 occupancy can be achieved.
Currently, there is one other PDE10 inhibitor being evaluated for the treatment of patients with HD.
Omeros chairman and chief executive officer Gregory Demopulos said: "Each of these disorders represents a significant unmet therapeutic need. Like treatments for schizophrenia, the only commercially available drug for Huntington's addresses narrowly limited symptoms of the disease and is associated with poorly tolerated side-effects.
"OMS824 holds the promise to expand the therapeutic reach across the disabling aspects of each of these diseases with better tolerability, and we look forward to additional clinical data later this year."