Omeros Announces Positive Data in Phase 1 Clinical Trial with OMS721

     Omeros Announces Positive Data in Phase 1 Clinical Trial with OMS721

-- Phase 2 Program Expected to Begin Enrollment Next Quarter --

PR Newswire

SEATTLE, Nov. 7, 2013

SEATTLE, Nov. 7, 2013 /PRNewswire/ -- Omeros Corporation (NASDAQ: OMER) today
announced positive clinical data in a Phase 1 clinical trial of OMS721, the
company's lead human monoclonal antibody targeting mannan-binding
lectin-associated serine protease-2 (MASP-2), an important regulatorof the
lectin pathway of the immune system. Subcutaneous administration of OMS721
achieved a high degree of lectin pathway inhibition. The drug was well
tolerated and no drug-related adverse events were observed. A Phase 2 clinical
program to evaluate OMS721 in the treatment of thrombotic microangiopathies
(TMAs), a family of disorders that occurs in the microcirculation of the
body's organs, most commonly the kidney and brain, is expected to begin
enrollment in early 2014. 

This Phase 1 trial is a placebo-controlled, double-blind,
single-ascending-dose study to evaluate the safety, tolerability,
pharmacodynamics and pharmacokinetics of OMS721 administered either
intravenously or subcutaneously in healthy subjects. To date, four cohorts of
subjects have received OMS721 or placebo by subcutaneous injection at
increasing dose levels. OMS721 or placebo injections were well tolerated in
all subjects. No clinically significant abnormalities on laboratory tests or
electrocardiograms have been observed. At the highest subcutaneous dose
administered to date, OMS721 achieved serum concentrations that resulted in a
high degree of inhibition of lectin pathway activation. The serum
concentrations seen in the Phase 1 subjects are similar to those associated
with efficacy in animal models of diseases linked to the lectin pathway,
including those of TMA and neovascular age-related macular degeneration (AMD),
a leading cause of vision loss in individuals over 60 years of age.

Earlier this year, Omeros reported positive data using OMS721 in a
well-established model of TMA. The company also recently announced preclinical
findings indicating that blockade of MASP-2 by OMS721 may provide a new
treatment for AMD. Omeros controls the worldwide rights to MASP-2 and all
therapeutics targeting MASP-2. MASP-2 is critical to the function of the
lectin pathway, one of the principal components of the complement system, a
key part of the immune response.

"We are pleased to see the safety profile and the high degree of lectin
pathway inhibition achieved with subcutaneous administration of OMS721 in this
trial," stated Gregory A. Demopulos, M.D., chairman and chief executive
officer of Omeros. "OMS721 could become the first subcutaneously administered
complement inhibitor on the market, addressing a wide range of immune-related
disorders, including atypical hemolytic uremic syndrome and other TMAs. We
look forward to initiating enrollment in our Phase 2 clinical program next

About Omeros' MASP-2 Program
Omeros controls the worldwide rights to MASP-2 and all therapeutics targeting
MASP-2, a novel pro-inflammatory protein target involved in activation of the
complement system, which is an important component of the immune system. The
complement system plays a role in the inflammatory response and becomes
activated as a result of tissue damage or microbial infection. MASP-2 appears
to be unique to, and required for the function of, one of the principal
complement activation pathways, known as the lectin pathway. Importantly,
inhibition of MASP-2 does not appear to interfere with the antibody-dependent
classical complement activation pathway, which is a critical component of the
acquired immune response to infection, and its abnormal function is associated
with a wide range of autoimmune disorders. MASP-2 is generated by the liver
and is then released into the circulation. Adult humans who are genetically
deficient in one of the proteins that activate MASP-2 do not appear to be
detrimentally affected by the deficiency. Therefore, Omeros believes that it
may be possible to deliver MASP-2 antibodies systemically and OMS721, its lead
MASP-2 antibody, is designed to be self-administered by subcutaneous

Omeros also believes that it has identified the proteins that activate the
complement system's alternative pathway in humans, which is linked to a wide
range of immune-related disorders. In addition to its lectin pathway
inhibitors, the Company is advancing the development of antibodies that would
block activation of the alternative pathway alone or in combination with the
lectin pathway.

About Omeros Corporation
Omeros is a clinical-stage biopharmaceutical company committed to discovering,
developing and commercializing small-molecule and protein therapeutics
targeting inflammation, coagulopathies and disorders of the central nervous
system. Derived from its proprietary PharmacoSurgery^® platform, the Company's
lead drug product, OMS302 for lens replacement surgery, is currently under
review for marketing approval by both the US Food and Drug Administration and
the European Medicines Agency with commercial launch planned for 2014. Omeros'
five other clinical programs are focused on schizophrenia, Huntington's
disease and cognitive impairment; addictive and compulsive disorders;
complement-related diseases; and preventing problems associated with surgical
procedures. Omeros also has a proprietary GPCR platform, which is making
available an unprecedented number of new GPCR drug targets and corresponding
compounds to the pharmaceutical industry for drug development.

Forward-Looking Statements
This press release contains forward-looking statements within the meaning of
Section 27A of the Securities Act of 1933 and Section 21E of the Securities
Exchange Act of 1934, which are subject to the "safe harbor" created by those
sections for such statements. All statements other than statements of
historical fact are forward-looking statements, which are often indicated by
terms such as "anticipate," "believe," "could," "estimate," "expect," "goal,"
"intend," "may," "plan," "potential," "predict," "project," "should," "will,"
"would" and similar expressions. 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, risks associated
with Omeros' unproven preclinical and clinical development activities,
regulatory oversight, commercialization of its products, intellectual property
claims and 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 August 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, 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,
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