(OMER) Announces Plan to File Infringement Suit Against ANDA Filer

SEATTLE, Aug. 17, 2015  — Omeros Corporation (NASDAQ: OMER) today, in response to investor questions, announced that it plans to file a patent infringement lawsuit against Par Pharmaceutical, Inc. and its subsidiary, Par Sterile Products, LLC (Par) in response to the Abbreviated New Drug Application (ANDA) filed by Par seeking FDA approval to market a generic version of Omeros’ commercial drug Omidria^® (phenylephrine and ketorolac injection) 1%/0.3%. Omidria is approved by the U.S. Food and Drug Administration (FDA) for use during cataract surgery or intraocular lens replacement to maintain pupil size by preventing intraoperative miosis (pupil constriction) and to reduce postoperative ocular pain. As reported in the company’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on August 10, 2015, Omeros received a notice from Par on July 27, 2015, which addresses the ANDA and Par’s request to market a generic version of Omidria pursuant to Paragraph IV of the Hatch-Waxman Act following expiration of the drug’s New Product Exclusivity and, if applicable, the subsequent Pediatric Exclusivity, but prior to the expiration of three patents published in the FDA’s Approved Drug Products with Therapeutic Equivalence Evaluations, or Orange Book, which have terms extending to as late as 2033. Approximately 3.8 million cataract and lens replacement procedures are projected in the U.S. in 2015.

Omeros currently owns 34 issued patents worldwide related to Omidria. The patents that are listed in the Orange Book were granted by multiple examiners in multiple art groups based on review of prior art from multiple searches. Omeros is highly confident in its patent estate protecting Omidria.

Omeros has reviewed Par’s Paragraph IV assertions and plans to file a patent infringement suit against Par within 45 days of Omeros’ receipt of Par’s notice. In this regard, Omeros has engaged a prominent Hatch-Waxman litigation team at Covington & Burling LLP. Filing of the planned lawsuit will trigger what is generally a 30-month stay of FDA action on Par’s ANDA. Issued U.S. patents are presumed to be valid, and only clear and convincing evidence presented in federal court can establish invalidity.  Independent of its patents, Omidria has also received 36-month market exclusivity through the New Product Exclusivity provided by the Federal Food, Drug, and Cosmetic Act as well as an additional six months of market exclusivity available upon successful completion of the company’s pediatric clinical plan according to the Written Request from FDA.

“Generic manufacturers challenging branded drug products is ‘business as usual’ in the pharmaceutical industry and, based on its track record this is not an uncommon activity for Par,” stated Gregory A. Demopulos M.D., chairman and chief executive officer of Omeros. “This action confirms our belief in the market potential of Omidria. We are confident in the strength of our product’s broad patent estate. We have engaged one of the premier biotech patent litigation teams in the country to pursue aggressively our case against Par, so I do not anticipate this effort becoming a distraction for Omeros. We remain focused on continuing to build on our successful launch of Omidria and on increasing the product’s market uptake.”

About Omidria^®
Omeros’ PharmacoSurgery^® product Omidria^® contains the mydriatic (pupil-dilating) agent phenylephrine and the anti-inflammatory agent ketorolac and was developed for use during cataract or other IOL replacement surgery. The FDA has approved Omidria for use during cataract surgery or IOL replacement to maintain pupil size by preventing intraoperative miosis (pupil constriction) and to reduce postoperative ocular pain.

Important Risk Information for Omidria^®
Systemic exposure of phenylephrine may cause elevations in blood pressure. In clinical trials, the most common reported ocular adverse reactions at two to 24 percent are eye irritation, posterior capsule opacification, increased intraocular pressure, and anterior chamber inflammation; incidence of adverse events was similar between placebo-treated and Omidria-treated patients. Omidria^® must be added to irrigation solution prior to intraocular use. Omidria is not approved for use in children.

About Omeros Corporation
Omeros is a biopharmaceutical company committed to discovering, developing and commercializing both small-molecule and protein therapeutics for large-market as well as orphan indications targeting inflammation, coagulopathies and disorders of the central nervous system. Derived from its proprietary PharmacoSurgery^® platform, the company’s first drug product, Omidria^® (phenylephrine and ketorolac injection) 1%/0.3%, has been approved by the FDA for use during cataract surgery or intraocular lens (IOL) replacement to maintain pupil size by preventing intraoperative miosis (pupil constriction) and to reduce postoperative ocular pain. In the European Union, European Commission has approved Omidria for use in cataract surgery and lens replacement procedures to maintain mydriasis (pupil dilation), prevent miosis (pupil constriction), and to reduce postoperative eye pain. Omeros has partnered its arthroscopic product, OMS103, for commercialization with Fagron Sterile Services and affiliated JCB Laboratories. Omeros has five clinical-stage development programs focused on: complement-related thrombotic microangiopathies; Huntington’s disease, schizophrenia, and cognitive impairment; and addictive and compulsive disorders. In addition, Omeros 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,” “look forward to,” “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, product commercialization including with respect to Omidria^® and OMS103, risks associated with Omeros’ ability to partner and commercialize Omidria in Europe, Omeros’ unproven preclinical and clinical development activities, regulatory oversight, intellectual property claims, competitive developments, litigation, 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 10, 2015. 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.