Investigational New Drug Application Cleared by FDA for OMS824 in Huntington's Disease

Investigational New Drug Application Cleared by FDA for OMS824 in Huntington's
                                   Disease

-- Clinical Trial in Patients with Huntington's Disease Slated to Begin Next
Quarter --

PR Newswire

SEATTLE, May 23, 2013

SEATTLE, May 23, 2013 /PRNewswire/ --Omeros Corporation (NASDAQ: OMER) today
announced that its Investigational New Drug Application (IND) to evaluate
OMS824 in Huntington's disease has been cleared by the U.S. Food and Drug
Administration (FDA). OMS824 selectively inhibits phosphodiesterase 10
(PDE10), an enzyme expressed in areas of the brain linked to a wide range of
diseases that affect cognition, including Huntington's disease and
schizophrenia. OMS824 has shown promising results in animal models directly
relevant to Huntington's disease and, as previously announced, OMS824 was well
tolerated and exhibited favorable pharmacokinetic properties in a Phase 1
clinical program. Omeros plans to advance OMS824 into Phase 2 clinical trials
for Huntington's disease next quarter and for schizophrenia later this year,
the OMS824 IND for use in patients with schizophrenia having already been
cleared by the FDA.

Omeros also announced today that it has requested Orphan Drug Designation from
the FDA for OMS824 in the treatment of Huntington's disease. Orphan-designated
drugs are eligible for incentives such as a faster approval process and
additional market exclusivity. This designation is granted to drugs that are
expected to provide significant therapeutic advantage over existing treatments
and that target conditions affecting 200,000 or fewer U.S. patients annually.
Huntington's disease is estimated to affect approximately 31,000 U.S. patients
annually, and the only FDA‑approved treatment for the disease is
tetrabenazine, which is indicated for Huntington's-related movement disorders.
Omeros recently announced that it has requested Fast Track designation for
OMS824 in the treatment for Huntington's disease. Fast Track designation is
reserved for drugs being developed to treat life-threatening conditions with
the potential to address unmet medical needs and typically provides priority
review status.

"Cognitive impairment is a hallmark of Huntington's disease and schizophrenia,
and there currently are no drugs that improve cognition in either disorder,"
stated Gregory A. Demopulos, M.D., chairman and chief executive officer of
Omeros. "In Huntington's disease, OMS824 also has the potential to improve
motor control and to reduce the rate of neurodegeneration, slowing disease
progression. We are pleased that the FDA has now cleared the way for us to
evaluate OMS824 in both patients with Huntington's disease and schizophrenia,
and we look forward to initiating enrollment in our Phase 2 clinical trials."

About Orphan Drug Status
Orphan drug designation is granted by the FDA's Office of Orphan Products
Development for drugs that are expected to provide significant therapeutic
advantage over existing treatments and that target conditions affecting
200,000 or fewer U.S. patients annually. Orphan drug designation qualifies a
company for several benefits under the Orphan Drug Act of 1983. The benefits
apply across all stages of drug development and include accelerated approval
process; seven years of market exclusivity following marketing approval; tax
credits on U.S. clinical trials; eligibility for orphan drug grants; and
waiver of certain administrative fees.

About FDA's Fast Track Program
The FDA's Fast Track program facilitates the development of drugs intended to
treat serious or life-threatening conditions and that have the potential to
address unmet medical needs. Fast Track drugs are eligible for more frequent
and timely meetings with the FDA to discuss the development plan and to ensure
that data needed for approval are collected appropriately. Drugs in the Fast
Track program typically are granted priority review status and their
respective New Drug Applications are accepted and reviewed by the FDA as
rolling submissions.

About Omeros' PDE10 Program
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. Huntington's disease is a hereditary
neurodegenerative disorder that leads to movement, cognition, and behavioral
abnormalities and premature death. Cognitive dysfunction is responsible for
substantial disability in these diseases and is not improved by current
medications. Omeros' proprietary compound OMS824 inhibits PDE10 and is being
developed for the treatment of cognitive disorders. In addition to potential
benefits on cognition, OMS824 could also improve psychiatric manifestations,
such as the positive (e.g., hallucinations) and negative (e.g., flat affect)
symptoms of schizophrenia.

About Omeros Corporation
Omeros is a clinical-stage biopharmaceutical company committed to discovering,
developing and commercializing products targeting inflammation, coagulopathies
and disorders of the central nervous system. The Company's most clinically
advanced product candidates, OMS302 for lens replacement surgery and OMS103HP
for arthroscopy, are derived from its proprietary PharmacoSurgery™ platform
designed to improve clinical outcomes of patients undergoing a wide range of
surgical and medical procedures. Omeros has five clinical development
programs. Omeros may also have the near-term capability, through its GPCR
program, to add a large number of new drug targets and their corresponding
compounds to the market. Behind its clinical candidates and GPCR platform,
Omeros is building a diverse pipeline of protein and small-molecule
preclinical programs targeting inflammation, coagulopathies and central
nervous system disorders.

Forward-Looking Statements
This press release contains forward-looking statements as defined within the
Private Securities Litigation Reform Act of 1995, which are subject to the
"safe harbor" created by those sections. These statements include, but are not
limited to, Omeros' expectations that it will advance OMS824 into Phase 2
clinical programs for Huntington's disease and schizophrenia this year;
regarding the potential therapeutic benefits of OMS824; and that it may have
capability, through its GPCR program, to add a large number of new drug
targets and their corresponding compounds to the market. Forward-looking
statements are based on management's beliefs and assumptions and on
information available to management only as of the date of this press release.
Omeros' actual results could differ materially from those anticipated in these
forward-looking statements for many reasons, including, without limitation,
the risks, uncertainties and other factors described under the heading "Risk
Factors" in the Company's Quarterly Report on Form 10-Q filed with the
Securities and Exchange Commission on May 9, 2013. Given these risks,
uncertainties and other factors, you should not place undue reliance on these
forward-looking statements, and the Company assumes no obligation to update
these forward-looking statements publicly, even if new information becomes
available in the future.

SOURCE Omeros Corporation

Contact: Jennifer Cook Williams, Cook Williams Communications, Inc., Investor
and Media Relations, +1-360-668-3701, jennifer@cwcomm.org