Omeros Corporation, a clinical-stage biopharmaceutical company committed to discovering, developing and commercializing small-molecules, has dosed its first patient in a second phase II clinical trial of OMS824, the company's phosphodiesterase 10 (PDE10) inhibitor being developed for the treatment of schizophrenia, Huntington's disease (HD) and other cognitive disorders. The phase II trial will evaluate the tolerability, safety, pharmacokinetics and performance on a battery of tests in patients with symptomatic HD.

Omeros previously reported results from its successful phase II trial of OMS824 in patients with schizophrenia. This second phase II trial will enroll approximately 120 patients with Huntington's disease who will be randomized 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 conducted in healthy subjects. The doses evaluated in this phase II trial are expected to be well tolerated and cover a range of PDE10 target occupancy in the brain. Efficacy will be assessed across three functional domains that are affected by the disease: motor, cognitive, and behavior. Patients in the trial 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 this year with final data projected to be available in 2015.

OMS824 has the potential to improve the cognitive and psychiatric abnormalities as well as the movement disorders associated with the disease. Omeros has been awarded Orphan Drug designation by the FDA to evaluate OMS824 in HD and recently received Fast Track designation from the FDA for the development of OMS824 to treat cognitive impairment in HD.

Omeros recently announced that approximately 70-per cent engagement at PDE10 was achieved in the positron emission tomography (PET) trial following dosing with OMS824 without evidence of extrapyramidal symptoms (EPS). There is currently one other PDE10 inhibitor being evaluated in patients with HD. Based on available information, OMS824 achieves greater PDE10 target occupancy without EPS than does any other PDE10 inhibitor previously or currently in development. Since the maximally tolerated dose of OMS824 has not been reached, Omeros plans to evaluate a higher dose of OMS824 in the PET trial to determine whether an even higher level of PDE10 occupancy can be achieved.

"The Omeros team continues to advance our OMS824 program rapidly and successfully for both of our initial clinical indications – Huntington's disease and schizophrenia," stated Gregory A Demopulos, MD, chairman and chief executive officer of Omeros. "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."

PDE10 is 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.