FDA Grants Orphan Drug Designation to Omeros’ Treatment for Stem Cell Transplant-Associated Thrombotic Microangiopathy

  • OMS721 also has orphan status for two other conditions
  • OMS721 is Omeros’ lead human MASP-2 antibody
  • The drug was awarded fast track designation for the treatment of patients with aHUS.

Omeros Corporation (NASDAQ:OMER) announced on 10/23/18 that OMS721 has received orphan drug designation from the FDA for the treatment of hematopoietic stem cell transplant-associated thrombotic microangiopathy (HSCT-TMA). OMS721 is Omeros’ lead human monoclonal antibody targeting mannan-binding lectin-associated serine protease-2 (MASP-2), the effector enzyme of the lectin pathway of the complement system. OMS721 was awarded breakthrough therapy designation for the treatment of high-risk HSCT-TMA earlier this year. Thrombotic microangiopathy is a life-threatening complication of HSCT, with reported mortality of greater than 90 percent in some high-risk patients.

This most recent orphan designation for OMS721 by FDA is consistent with Omeros’ Phase 3 program in HSCT-TMA and, therefore, confers to OMS721 on approval for this indication all the benefits of orphan drug designation. OMS721 also has orphan designation in the U.S. for immunoglobulin A (IgA) nephropathy and for the prevention (inhibition) of complement-mediated TMA, including HSCT-TMA and atypical hemolytic uremic syndrome (aHUS). Omeros has active Phase 3 programs for OMS721 in HSCT-TMA, IgA nephropathy, and aHUS.

“With FDA’s granting of an additional orphan drug designation for OMS721 for stem cell transplant-associated TMA, we now have orphan designations that cover both the prevention and treatment of this disorder with OMS721 in the U.S. as well as in Europe,” stated Gregory A. Demopulos, M.D., chairman and chief executive officer of Omeros. “We continue to work with FDA and European regulators as we pursue expedited pathways to OMS721 approval in stem-cell TMA. Our objective is to make this drug -- which we and leading experts believe is saving lives – available to transplanters and their patients as quickly as possible.”

OMS721 is Omeros’ lead human MASP-2 antibody. 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.

Phase 3 clinical programs are in progress for OMS721 in atypical hemolytic uremic syndrome (aHUS), in immunoglobulin A (IgA) nephropathy and in hematopoietic stem cell transplant-associated thrombotic microangiopathy (HSCT-TMA). Also, two Phase 2 trials are ongoing. One is continuing to enroll IgA nephropathy patients and has already generated positive data in patients with IgA nephropathy and with lupus nephritis; the other is enrolling and has reported positive data in patients with HSCT-TMA and in patients with aHUS. OMS721 can be administered both intravenously and subcutaneously, and Omeros expects to commercialize each formulation of OMS721 for different therapeutic indications. In parallel, Omeros is 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. The FDA has granted OMS721 breakthrough therapy designation for IgA nephropathy and for high-risk HSCT-TMA, orphan drug status for the prevention (inhibition) of complement-mediated thrombotic microangiopathies and for the treatment of IgA nephropathy, and fast track designation for the treatment of patients with aHUS.

In early October of this year, Omeros released positive results of a study of OMS721 in patients with IgA nephropathy.