Omeros Reports Significant Improvement in Overall Survival Data in OMS721-Treated Patients with Hematopoietic Stem Cell Transplant-Associated Thrombotic Microangiopathy
-- Greater than 16-Fold Improvement in Survival Compared to Historical Control --
A total of 19 HCT-TMA patients have been treated to date with OMS721, 18 in the ongoing study and one patient under a compassionate use protocol. An historical control that best matched the OMS721-treated population was identified from the literature. The literature reference selection criteria were those studies that specified: (1) individual patient data (required for analysis), (2) adult and/or adolescent populations, (3) allogeneic stem cell transplant recipients only, and (4) no or partial response to immunosuppressive regimen modification. Overall median survival demonstrated greater than 16-fold improvement in survival in the OMS721-treated group (p < 0.0001).
Markers of TMA activity in study participants, specifically mean platelet count, mean LDH, and mean haptoglobin, continue to demonstrate statistically and clinically significant improvements following OMS721 treatment. At the end of protocol-allowed treatment, the mean platelet count (normal range: 150,000 – 400,000 x 106/mL) increased from 18,100 x 106/mL at baseline to 52,300 x 106/mL (p = 0.017). The mean LDH (normal range: 125-220 U/L) decreased from 591 U/L at baseline to 250 U/L (p < 0.001). The mean haptoglobin (normal range: 14-268 mg/dL) increased from 8 mg/dL at baseline to 141 mg/dL (p = 0.003). Mean creatinine remained stable at approximately 120 μmol/L (normal range: 63-104 μmol/L) but a majority of patients had co-existing conditions for which they were receiving nephrotoxic medications. Other serious co-existing conditions included graft versus host disease (GvHD), cytomegalovirus and human herpes virus 6 infections, prior sepsis, diffuse alveolar hemorrhage, and residual underlying malignancies.
OMS721 has been well tolerated and no safety concerns have been identified. The most commonly reported adverse events were diarrhea and neutropenia. Four deaths occurred during the study: one due to progression of acute myeloid leukemia, two due to neutropenic sepsis, and one due to acute renal and respiratory failure. Only one of these deaths – the acute renal and respiratory failure – was considered “possibly drug-related” because an association could not be definitively ruled out by the investigator. These are common complications of HCT. The other three deaths were deemed not to be related to OMS721.
Earlier data from this study have previously been presented at the 2017
combined annual meetings of the Center for
“As evidenced by the published literature, this is a population with an
extremely high mortality rate and a disorder for which there is no
approved therapy, and the improvement in survival in these patients with
OMS721 is compelling,” stated
In the Phase 2 HCT-TMA clinical trial, patients receive weekly OMS721 treatments for four or eight weeks, at the discretion of the investigator. To be eligible for enrollment, HCT-TMA patients are required to be adults with post-transplant TMA persisting at least two weeks following immunosuppressive regimen modification (conservative treatment) or more than 30 days post-transplant. This population was chosen to represent a population at risk for poor outcomes, including mortality. These patients often have severe co-existing conditions, and mortality rates have been reported to be as high as 100 percent.
“Hematopoietic stem cell transplantation is a potentially curative and
life-saving medical procedure but is far too often complicated by
thrombotic microangiopathy, for which serious cases carry an
unacceptably high mortality rate,” stated
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.
About Graft-versus-Host Disease
Graft-versus-host disease is a common complication of HCT. Both acute and chronic forms exist and result from donor immune cells recognizing the recipient patient as foreign tissue. This triggers an immune response against the recipient patient. Acute GvHD occurs in up to 50% or more of patients who receive allogeneic transplants. Acute GvHD most commonly targets the skin, gastrointestinal tract, and liver, but can also affect the kidney, eye, lung, and blood cells. Chronic GvHD occurs in approximately 40% of patients who receive allogeneic transplants and most commonly affects the skin, liver, eye, gastrointestinal tract and lungs. Both acute and chronic GvHD are related to significant morbidity and mortality.
About Omeros’ MASP Programs
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 (HCT-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
HCT-TMA and in patients with aHUS. OMS721 can be administered both
intravenously and subcutaneously, and
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Cook Williams Communications, Inc.
Jennifer Cook Williams, 360-668-3701
Investor and Media Relations