Omeros Reports Positive Data Across Primary and Secondary Endpoints in Pivotal Trial of Hematopoietic Stem Cell Transplant-Associated Thrombotic Microangiopathy Patients Treated with Narsoplimab
– 56 Percent of All Narsoplimab-Treated Patients Were Complete Responders by Primary Endpoint, Achieving Full Set of Response Criteria Agreed by
– 100-Day Survival Across All Narsoplimab-Treated Patients Was 65 Percent; 93 Percent for Complete Responders –
– Statistically Significant (p < 0.01) Improvements in Platelet Count, LDH and Haptoglobin Across All Groups of Narsoplimab-Treated Patients –
– No Signal of Any Serious Safety Risk Observed in the Trial; Adverse Events Comparable to Those Commonly Seen in Stem-Cell Transplant –
– Conference Call and Webcast Today at
The primary efficacy endpoint in this single-arm open-label trial of HSCT-TMA patients is the proportion of patients who achieve a highly rigorous set of response criteria that requires both improvement in HSCT-TMA laboratory markers and improvement in clinical status (organ function and transfusions). Patients who did not fully meet these criteria were considered non-responders. The secondary endpoints include survival rates and change from baseline in HSCT-TMA laboratory markers. Consistent with the pre-specified statistical analysis plan for the trial, the primary and secondary endpoints are assessed for (1) all patients who received at least one dose of narsoplimab and (2) patients who received at least 4 weeks of narsoplimab dosing. Patients enrolled in this trial had a high expected mortality rate. In severe cases of HSCT-TMA, mortality can exceed 90 percent.
Primary Efficacy Endpoint:
56 percent of all patients receiving at least one dose of narsoplimab achieved complete responder status (met full set of
FDA-agreed response criteria).
- 68 percent of patients who received the protocol-specified narsoplimab treatment of at least 4 weeks of dosing achieved complete responder status.
- 100-day survival following HSCT-TMA diagnosis for all patients receiving at least one dose of narsoplimab was 65 percent.
- 100-day survival following HSCT-TMA diagnosis for patients who received the protocol-specified treatment of at least 4 weeks of narsoplimab dosing was 81 percent.
- 100-day survival following HSCT-TMA diagnosis in the complete responder group was 93 percent.
Substantial and statistically significant improvements in platelet count, LDH and haptoglobin were observed across all of the following groups:
- All patients who received at least one dose of narsoplimab (p < 0.01 for each laboratory value)
- Patients who received protocol-specified treatment of at least 4 weeks of dosing (p ≤ 0.002 for each laboratory value)
- Complete responders (p < 0.001 for each laboratory value).
- Hemoglobin increased across all groups and reached statistical significance (p = 0.041) in complete responders.
- Creatinine also improved meaningfully in all patient groups but did not reach statistical significance given the use of nephrotoxic agents in trial patients.
- No signal of any serious safety risk has been observed with narsoplimab in the trial.
- The most common adverse events seen in this trial were nausea, vomiting, diarrhea, hypokalemia, neutropenia and fever – all common in stem-cell transplant patients.
- 21 percent of patients died during the trial due to causes common in stem cell transplant, with no additional patients discontinuing for adverse events. The data from the patients who died were not excluded from any analyses.
The HSCT-TMA patient population enrolled in this trial had multiple high-risk features that portend a poor outcome. These include persistence of HSCT-TMA despite modification of immunosuppression (which was a criterion for entry into the trial), graft-versus-host disease, significant infections, non-infectious pulmonary complications and neurological findings. Patients in the trial had a high expected death rate, with 93 percent of them having multiple risk factors.
Patient enrollment in the pivotal trial has been completed. The details of the endpoints, including the response criteria agreed with
Last year the company reported data on 19 HSCT-TMA patients treated with narsoplimab on which
“The response rate in this high-risk population would be expected to be 10 to 15 percent with a 100-day survival rate of less than 20 percent. The response rate and 100-day survival achieved with narsoplimab in this trial demonstrate an unprecedented effect in this condition,” said
“The striking results seen in our pivotal trial are tremendously gratifying,” said
Data from this pivotal trial will also support the narsoplimab marketing authorization application for HSCT-TMA in
In addition to breakthrough therapy designation from
Conference Call and Webcast Details
Omeros’ management will host a webcast and conference call to present data from its pivotal trial of narsoplimab in HSCT-TMA. The call will be held today at
To access the live or subsequently archived webcast and presentation materials on the internet, go to the company’s website at www.omeros.com and select “Events” under the Investors section of the website. To access the live webcast, please connect to the website at least 15 minutes prior to the call to allow for any software download that may be necessary.
Hematopoietic stem cell transplant-associated thrombotic microangiopathy (HSCT-TMA) is a significant and often lethal complication of stem cell transplants. This condition is a systemic, multifactorial disorder caused by endothelial cell damage induced by conditioning regimens, immunosuppressant therapies, infection, GvHD, and other factors associated with stem cell transplantation. Endothelial damage, which activates the lectin pathway of complement, plays a central role in the development of HSCT-TMA. The condition occurs in both autologous and allogeneic transplants but is more common in the allogeneic population. In
Narsoplimab, also known as “OMS721,” is an investigational human monoclonal antibody targeting mannan-binding lectin-associated serine protease-2 (MASP-2), a novel pro-inflammatory protein target and the effector enzyme of the lectin pathway of complement. 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.
Phase 3 clinical programs are in progress for narsoplimab in hematopoietic stem cell transplant-associated thrombotic microangiopathy (HSCT-TMA), in immunoglobulin A (IgA) nephropathy, and in atypical hemolytic uremic syndrome (aHUS). The
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,” “likely”, “look forward to,” “may,” “on track,” “plan,” “potential,” “predict,” “project,” “prospects,” “scheduled,” “should,” “slated,” “targeting,” “will,” “would” and similar expressions and variations thereof. Forward-looking statements, including statements regarding anticipated regulatory submissions, expectations regarding regulatory exclusivities, the timing and results of ongoing or anticipated clinical trials, and the therapeutic application of Omeros’ investigational product, 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, availability and timing of data from clinical trials and the results of such trials, 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 Annual Report on Form 10-K filed with the
Jennifer Cook Williams
Cook Williams Communications, Inc.
Investor and Media Relations