Omeros Reports Additional Positive Results From OMS721 Phase II Trial In Patients With Stem Cell Transplant-Associated Thrombotic Microangiopathy

--Data Presented at the Recent Combined International and American Blood & Marrow Transplantation Meetings--

SEATTLE--(BUSINESS WIRE)-- Omeros Corporation (NASDAQ: OMER) today announced additional positive data from the ongoing Phase 2 clinical trial evaluating OMS721 in the treatment of hematopoietic stem cell transplant-associated thrombotic microangiopathy (HCT-TMA). These data were presented at the combined annual meetings of the Center for International Blood & Marrow Transplant Research (CIBMTR) and the American Society for Blood and Marrow Transplantation (ASBMT). The presentation, “Early Results of a Phase 2 Study Using OMS721 in Patients with Hematopoietic Stem Cell Transplant-Associated Thrombotic Microangiopathy (HCT-TMA),” summarized clinical data from the seven HCT-TMA patients who to date have been treated with OMS721. Samer Khaled, M.D., Assistant Clinical Professor of Hematology & Hematopoietic Cell Transplantation at City of Hope, presented the data Saturday, February 25, 2017.

The Phase 2 uncontrolled clinical trial is ongoing in patients with one of three types of TMA, including HCT-TMA. To be eligible for enrollment, HCT-TMA patients are required to be adults with post-transplant TMA persisting at least two weeks following calcineurin inhibitor modification (conservative treatment). This population is at high risk for poor outcomes, including mortality. The primary efficacy endpoint of the study is change in platelet count. Additional efficacy endpoints include changes in lactate dehydrogenase (LDH) and haptoglobin levels.

The presentation included multiple figures summarizing these efficacy measures following treatment with OMS721. Consistent with previously reported results, statistically significant and clinically meaningful improvements in TMA disease activity were observed over the course of treatment, specifically in mean platelet count, mean LDH and mean haptoglobin. Mean creatinine also improved but did not reach statistical significance.

“TMA following stem cell transplantation can be a devastating complication, especially in these patients who had failed conservative treatment,” stated Dr. Khaled. “Their respective prognoses were poor, and the positive responses that we have observed with OMS721 are truly impressive. We are continuing to enroll patients in this study and I look forward to working with Omeros to move OMS721 through further development.” Thrombotic microangiopathy is a potentially life-threatening complication of HCT. Approximately 20,000 HCT procedures are performed in the U.S. annually, and TMA is reported to occur in approximately 10 to 25 percent of HCT patients. Although the kidney is the most commonly affected organ, HCT-TMA is a multi-system disorder and can also manifest clinically in the lungs, gastrointestinal tract and central nervous system. Reported mortality in patients with multi-organ involvement is greater than 90%. Even in patients who survive acute episodes, HCT-TMA increases the risk for chronic kidney disease and end-stage renal disease.

The most common adverse events observed to date in the study have been diarrhea, abdominal pain, anemia, neutropenia, hyperbilirubinemia, hyperkalemia and graft-versus-host disease, all of which commonly occur with HCT. A total of ten serious adverse events have been reported, none considered related to OMS721 treatment. Two patients died of progression of cancer after less than three weeks of OMS721 treatment and one patient died of graft failure after completing the study and positively responding to OMS721. None of these deaths was considered by the investigators to be related to OMS721 treatment.

“We are excited about the consistently positive results in this study,” stated Gregory A. Demopulos M.D., chairman and chief executive officer of Omeros. “HCT-TMA is frequently fatal and there is no approved treatment. We plan to discuss our data with the FDA and international regulatory agencies as we continue to design an efficient Phase 3 program with the objective of accelerating access to OMS721 for physicians and their patients.”

Additional data related to treatment of HCT-TMA with OMS721 will be presented at the Annual Meeting of the European Society of Blood and Marrow Transplantation in Marseille, France later next month.

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 is the effector enzyme of the lectin pathway, one of the principal complement activation pathways. 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 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. Omeros has received both Orphan Drug status and Fast Track designation from the U.S. FDA for its lead human MASP-2 antibody OMS721. Following discussions with both the FDA and the European Medicines Agency, a Phase 3 program for OMS721 in atypical hemolytic uremic syndrome is in progress. Also, two Phase 2 trials are ongoing. One is evaluating OMS721 in glomerulonephropathies, which has generated positive data in patients with immunoglobulin A (IgA) nephropathy and with membranous nephropathy and the other is being conducted in patients with thrombotic microangiopathies (TMAs), with positive data reported in patients with hematopoietic stem cell transplant-associated TMA. In addition to potential intravenous administration, Omeros plans to commercialize OMS721 for one or more therapeutic indications as a subcutaneous injection and is also developing small-molecule inhibitors of MASP-2. Based on requests from treating physicians, Omeros has established a compassionate-use program for OMS721, which is active in both the U.S. and Europe.

Omeros also has identified MASP-3 as the protein that is critical to the activation of 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 its development of antibodies and small-molecule inhibitors against MASP-3 to block activation of the alternative pathway.

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. Part of its proprietary PharmacoSurgery® platform, the company’s first drug product, OMIDRIA® (phenylephrine and ketorolac injection) 1% / 0.3%, was broadly launched in the U.S. in April 2015. OMIDRIA is the first and only FDA-approved drug (1) 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 and (2) that contains an NSAID for intraocular use. In the European Union, the 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 clinical-stage development programs focused on: complement-associated thrombotic microangiopathies; complement-mediated glomerulonephropathies; Huntington’s disease and cognitive impairment; and addictive and compulsive disorders. In addition, Omeros has a proprietary G protein-coupled receptor (GPCR) platform, which is making available an unprecedented number of new GPCR drug targets and corresponding compounds to the pharmaceutical industry for drug development, and a platform used to generate antibodies.

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