Thrombotic MicroangiopathiesPhase 3aHUSNCT03205995
Safety and Efficacy Study of OMS721 in Patients With Atypical Hemolytic Uremic Syndrome
A Phase 3 study testing OMS721 (narsoplimab) in people with Thrombotic Microangiopathies and Atypical Hemolytic Uremic Syndrome, run by Omeros Corporation at 4 sites in 4 countries.
Trial summary
The purpose of this study is to evaluate the platelet count change from baseline and safety of OMS721 (narsoplimab) in adults and adolescents with atypical hemolytic uremic syndrome (aHUS). The study will also evaluate pharmacokinetics (PK), pharmacodynamics (PD), and anti-drug antibody response (ADA). Read more about this study
- Who is it for?
- Ages 12 years and older
- Conditions the study is for
- Thrombotic Microangiopathies, Atypical Hemolytic Uremic Syndrome
- What is being tested?
- OMS721 (narsoplimab)
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 6 participants
- Where
- 4 sitesin 4 countries
- Study dates
- 2 May 2018to 2 Feb 2021
- Phase
- Phase 3
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 12 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Are age >= 12 years old at screening (Visit 1).
- Have a primary aHUS, diagnosed clinically, and have ADAMTS13 activity > 5% in plasma. Participants are eligible with or without a documented complement mutation or anti-CFH antibody. Participants are categorized according to their response to plasma therapy (plasma exchange or plasma infusion):
- Plasma therapy-resistant aHUS participants must have all of the following:
- Screening platelet count < 150,000/μL despite at least four plasma therapy treatments in a 7-day period prior to screening
- Evidence of microangiopathic hemolysis (at least one of:
- presence of schistocytes,
Show all 16Show fewer
- serum LDH > 1.5 times upper limit of normal (ULN), and
- haptoglobin < LLN)
- Serum creatinine > ULN
- Plasma therapy-responsive aHUS participants must have all of the following:
- Have a documented history of requiring plasma therapy to prevent aHUS exacerbation defined as all of the following:
- decrease in platelet count > 25% when plasma therapy frequency has been decreased (including discontinuation of plasma therapy)
- LDH > 1.5 times ULN when plasma therapy frequency has been decreased (including discontinuation of plasma therapy)
- Have received plasma therapy at least once every 2 weeks at an unchanged frequency for at least 8 weeks before first dose of OMS721
- If sexually active and of childbearing potential, must agree to practice a highly effective method of birth control until the end of the study, defined as one that results in a low failure rate (i.e., less than 1% per year) when used consistently and correctly, such as implants, injectables, combined oral contraceptives, some intrauterine devices, sexual abstinence or vasectomized partner.
- Do not have access to eculizumab treatment, have not derived therapeutic benefit from eculizumab treatment, or have not been able to tolerate eculizumab treatment.
Who cannot join
- Have STEC-HUS.
- Have a positive direct Coombs test.
- Have a history of hematopoietic stem cell transplant.
- Have HUS from an identified drug.
- History of vitamin B12 deficiency-related HUS.
- History of Systemic Lupus Erythematosus.
Show all 25Show fewer
- History of antiphospholipid syndrome.
- Active cancer or history of cancer (except non-melanoma skin cancers) within 5 years of screening.
- Have been on hemodialysis or peritoneal dialysis for ≥ 12 weeks.
- Have an active systemic bacterial or fungal infection requiring systemic antimicrobial therapy (prophylactic antimicrobial therapy administered as standard of care is allowed).
- Baseline resting heart rate < 45 beats per minute or > 115 beats per minute.
- Baseline QTcF > 470 milliseconds.
- Have malignant hypertension (diastolic blood pressure [BP] > 120 mm Hg with bilateral hemorrhages or "cotton-wool" exudates on funduscopic examination).
- Have a poor prognosis with a life expectancy of less than three months in the opinion of the Investigator.
- Are pregnant or lactating.
- Have received treatment with an investigational drug or device within four weeks of the screening visit.
- Have abnormal liver function tests defined as ALT or AST > five times ULN.
- Have HIV infection.
- History of cirrhosis of the liver.
- Are an employee of Omeros, an Investigator, a study staff member, or their immediate family member.
- Have a known hypersensitivity to any constituent of the product.
- Presence of any condition that the Investigator believes would put the subject at risk or confound the interpretation of the data.
- Have previously completed treatment in an OMS721study.
- Have received intravenous immunoglobulin (IVIG) treatment within 8 weeks of screening visit.
- Have received rituximab within 24 weeks of screening visit.
Trial locations and contacts
4 sites in 4 countries.
4 sites in 4 countries
United States1 site
Omeros Investigational Site
Chicago, Illinois, 60643
About this study
Official title: A Phase 3 Study to Evaluate the Safety and Efficacy of OMS721 for the Treatment of Atypical Hemolytic Uremic Syndrome (aHUS) in Adults and Adolescents
The purpose of this study is to evaluate the platelet count change from baseline and safety of OMS721 (narsoplimab) in adults and adolescents with atypical hemolytic uremic syndrome (aHUS). The study will also evaluate pharmacokinetics (PK), pharmacodynamics (PD), and anti-drug antibody response (ADA).
Read the detailed description
This is a Phase 3, uncontrolled, open-label study to evaluate the effect of OMS721 in subjects with aHUS. The primary outcome to be measured is platelet count change from baseline. The secondary outcomes to be measured are other efficacy measures, safety, PK, PD, and immunogenicity (i.e., presence of anti-drug antibody [ADA] response. Subjects with plasma therapy-resistant aHUS and plasma therapy-responsive aHUS will be eligible. The efficacy endpoints, including the primary efficacy endpoint, may not be relevant for plasma therapy-responsive subjects because these subjects may enter the study with normal markers of aHUS activity due to successful treatment with plasma therapy. Therefore, efficacy analyses will be performed separately in the plasma therapy-resistant and plasma therapy responsive subjects. The principal efficacy analyses will be the analyses in the plasma therapy resistant cohort and efficacy analyses of the plasma therapy-responsive cohort will be supportive. Safety analyses will be conducted in all subjects.
- Being tested
- OMS721 (narsoplimab)
- Keywords
- TMA, aHUS
- Medical subject headings
- Thrombotic Microangiopathies, Atypical Hemolytic Uremic Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
OMS721 (narsoplimab)Biological
Also called narsoplimab
Intravenous loading dose followed by daily subcutaneous injections
| Study group | Role | What they receive |
|---|---|---|
| OMS721 (narsoplimab) | Experimental | Administration of OMS721 (narsoplimab) Receives: Biological: OMS721 (narsoplimab) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Platelet Count (10^9 Platelets/L) Change From Baseline at Week 26
The primary outcome to be measured is platelet count change from baseline.
Measured: Week 26
Secondary outcomes (15)
Safety as Measured by Incidences of Adverse Events, Vital Signs, ECG, and Clinical Laboratory Tests
Assessment of safety of OMS721 (narsoplimab) in participants with aHUS by incidence of Adverse Events, clinically significant vital sign abnormalities, ECG abnormalities, and clinical laboratory test abnormalities
Measured: Pre-dose and up to 771 days post-dose
Thrombotic Microangiopathies (TMA) Response
Complete TMA response defined as normalization of platelet count, normalization of serum lactate dehydrogenase (LDH), and > 25% decrease in serum creatinine by at least 2 consecutive measures over at least 4 consecutive weeks, within the initial 26-week period
Measured: 26 weeks
TMA Event-free Status
No decrease in platelet count of > 25% from baseline, no plasma exchange or plasma infusion, and no initiation of new dialysis over at least 12 consecutive weeks, within the initial 26-week period
Measured: 26 weeks
Increase in Estimated Glomerular Filtration Rate (eGFR)
Increase of greater than 15 ml/min/1.73 m2 in eGFR calculated by the modification of diet in renal disease (MDRD) Equation
Measured: 26 weeks
Hematological Normalization
Normalization of platelet count and normalization of serum LDH by 2 consecutive measurements over at least 4 weeks, within the initial 26-week period
Measured: 26 weeks
TMA Remission
Platelet count greater than or equal to 150,000/μL on at least 2 consecutive measures over at least 2 consecutive weeks, within the initial 26-week period
Measured: 26 weeks
Incidence of Antidrug Antibodies (ADA)
Incidences of ADA in participants with aHUS, administered OMS721 (narsoplimab)
Measured: 771 days post-dose
Change From Baseline in Serum Creatinine (mg/dL)
Assessment of subject's change from baseline in serum creatinine.
Measured: 26 weeks
Change From Baseline in Serum LDH (U/L)
Assessment of subject's change from baseline in serum LDH
Measured: 26 weeks
Change From Baseline in Haptoglobin (mg/dL)
Assessment of subject's change from baseline in haptoglobin
Measured: 26 weeks
Pharmacokinetics (PK): Trough Plasma Concentration, Lower Limit of Quantification (LLOQ)
Pharmacokinetics (PK): Trough plasma concentration, lower limit of quantification (LLOQ)
Measured: Days 1-4; Treatment Maintenance (103 weeks): 17 visits; Rescue Therapy (RT) (if occurs): RT Days 1-4; Follow-Up at Day 771
Pharmacokinetics (PK): Maximum Plasma Concentrations (Cmax)
Pharmacokinetics (PK): Maximum plasma concentrations (Cmax)
Measured: Days 1-4; Treatment Maintenance (103 weeks): 17 visits; Rescue Therapy (if occurs): RT Days 1-4; Follow-Up at Day 771
Pharmacokinetics (PK): Area Under Time-concentration Curve (AUC)
Pharmacokinetics (PK): Area under time-concentration curve (AUC)
Measured: Days 1-4; Treatment Maintenance (103 weeks): 17 visits; Rescue Therapy (if occurs): RT Days 1-4; Follow-Up at Day 771
Pharmacodynamics (PD): Inhibition of C3 Activity (%)
Pharmacodynamics (PD): Inhibition of C3 activity
Measured: Days 1-4; Treatment Maintenance (103 weeks): 17 visits; Rescue Therapy (if occurs): RT Days 1-4; Follow-Up at Day 771
Pharmacodynamics (PD): Inhibition of C4 Activity (%)
Pharmacodynamics (PD): Inhibition of C4 activity
Measured: Days 1-4; Treatment Maintenance (103 weeks): 17 visits; Rescue Therapy (if occurs): RT Days 1-4; Follow-Up at Day 771
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Jul 2017
- Study start2 May 2018
- Primary completion2 Feb 2021
- Study completion2 Feb 2021
Why it stopped: Sponsor terminated study
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Thrombotic MicroangiopathiesStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 6 participants (actual)
Sponsor and investigators
- Lead sponsor
- Omeros Corporation
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03205995
- Sponsor's protocol ID
- OMS721-HUS-002
- Acronym
- aHUS
- Status last verified
- Nov 2025
- First submitted
- 17 Apr 2017
- Last updated
- 10 Dec 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
- Expanded access
- Available
Publications
Pugh D, O'Sullivan ED, Duthie FA, Masson P, Kavanagh D. Interventions for atypical haemolytic uraemic syndrome. Cochrane Database Syst Rev. 2021 Mar 23;3(3):CD012862. doi: 10.1002/14651858.CD012862.pub2.
PubMed 33783815
Study at a glance
From the registry record, last updated by the sponsor on 10 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 3 Study to Evaluate the Safety and Efficacy of OMS721 for the Treatment of Atypical Hemolytic Uremic Syndrome (aHUS) in Adults and Adolescents
- ClinicalTrials.gov ID
- NCT03205995
- Acronym / sponsor ID
- aHUS / OMS721-HUS-002
- Keywords
- TMA, aHUS
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Sponsor terminated study
- Enrolment
- 6 participants (actual)
- Lead sponsor
- Omeros CorporationIndustry (pharma, biotech, devices)
- Study start
- 2 May 2018 (actual)
- Primary completion
- 2 Feb 2021 (actual)
- Study completion
- 2 Feb 2021 (actual)
- First posted
- 2 Jul 2017 (actual)
- Results
- Posted 10 Dec 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study is to evaluate the platelet count change from baseline and safety of OMS721 (narsoplimab) in adults and adolescents with atypical hemolytic uremic syndrome (aHUS). The study will also evaluate pharmacokinetics (PK), pharmacodynamics (PD), and anti-drug antibody response (ADA).
Detailed description
This is a Phase 3, uncontrolled, open-label study to evaluate the effect of OMS721 in subjects with aHUS. The primary outcome to be measured is platelet count change from baseline. The secondary outcomes to be measured are other efficacy measures, safety, PK, PD, and immunogenicity (i.e., presence of anti-drug antibody [ADA] response. Subjects with plasma therapy-resistant aHUS and plasma therapy-responsive aHUS will be eligible. The efficacy endpoints, including the primary efficacy endpoint, may not be relevant for plasma therapy-responsive subjects because these subjects may enter the study with normal markers of aHUS activity due to successful treatment with plasma therapy. Therefore, efficacy analyses will be performed separately in the plasma therapy-resistant and plasma therapy responsive subjects. The principal efficacy analyses will be the analyses in the plasma therapy resistant cohort and efficacy analyses of the plasma therapy-responsive cohort will be supportive. Safety analyses will be conducted in all subjects.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| OMS721 (narsoplimab) | Experimental | Biological: OMS721 (narsoplimab)Administration of OMS721 (narsoplimab) |
Who may qualify
- Ages
- 12 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (16 listed)
- Are age >= 12 years old at screening (Visit 1).
- Have a primary aHUS, diagnosed clinically, and have ADAMTS13 activity > 5% in plasma. Participants are eligible with or without a documented complement mutation or anti-CFH antibody. Participants are categorized according to their response to plasma therapy (plasma exchange or plasma infusion):
- If sexually active and of childbearing potential, must agree to practice a highly effective method of birth control until the end of the study, defined as one that results in a low failure rate (i.e., less than 1% per year) when used consistently and correctly, such as implants, injectables, combined oral contraceptives, some intrauterine devices, sexual abstinence or vasectomized partner.
- Do not have access to eculizumab treatment, have not derived therapeutic benefit from eculizumab treatment, or have not been able to tolerate eculizumab treatment.
Key exclusion criteria (25 listed)
- Have STEC-HUS.
- Have a positive direct Coombs test.
- Have a history of hematopoietic stem cell transplant.
- Have HUS from an identified drug.
- History of vitamin B12 deficiency-related HUS.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| OMS721 (narsoplimab)Also: narsoplimabIntravenous loading dose followed by daily subcutaneous injections | Biological | OMS721 (narsoplimab) |
Primary outcome
Platelet Count (10^9 Platelets/L) Change From Baseline at Week 26
Time frame: Week 26
The primary outcome to be measured is platelet count change from baseline.
15 secondary outcomes
Safety as Measured by Incidences of Adverse Events, Vital Signs, ECG, and Clinical Laboratory Tests
Time frame: Pre-dose and up to 771 days post-dose
Thrombotic Microangiopathies (TMA) Response
Time frame: 26 weeks
TMA Event-free Status
Time frame: 26 weeks
Increase in Estimated Glomerular Filtration Rate (eGFR)
Time frame: 26 weeks
Hematological Normalization
Time frame: 26 weeks
TMA Remission
Time frame: 26 weeks
Incidence of Antidrug Antibodies (ADA)
Time frame: 771 days post-dose
Change From Baseline in Serum Creatinine (mg/dL)
Time frame: 26 weeks
Change From Baseline in Serum LDH (U/L)
Time frame: 26 weeks
Change From Baseline in Haptoglobin (mg/dL)
Time frame: 26 weeks
Pharmacokinetics (PK): Trough Plasma Concentration, Lower Limit of Quantification (LLOQ)
Time frame: Days 1-4; Treatment Maintenance (103 weeks): 17 visits; Rescue Therapy (RT) (if occurs): RT Days 1-4; Follow-Up at Day 771
Pharmacokinetics (PK): Maximum Plasma Concentrations (Cmax)
Time frame: Days 1-4; Treatment Maintenance (103 weeks): 17 visits; Rescue Therapy (if occurs): RT Days 1-4; Follow-Up at Day 771
Pharmacokinetics (PK): Area Under Time-concentration Curve (AUC)
Time frame: Days 1-4; Treatment Maintenance (103 weeks): 17 visits; Rescue Therapy (if occurs): RT Days 1-4; Follow-Up at Day 771
Pharmacodynamics (PD): Inhibition of C3 Activity (%)
Time frame: Days 1-4; Treatment Maintenance (103 weeks): 17 visits; Rescue Therapy (if occurs): RT Days 1-4; Follow-Up at Day 771
Pharmacodynamics (PD): Inhibition of C4 Activity (%)
Time frame: Days 1-4; Treatment Maintenance (103 weeks): 17 visits; Rescue Therapy (if occurs): RT Days 1-4; Follow-Up at Day 771
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Dec 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 33783815Pugh D, O'Sullivan ED, Duthie FA, Masson P, Kavanagh D. Interventions for atypical haemolytic uraemic syndrome. Cochrane Database Syst Rev. 2021 Mar 23;3(3):CD012862. doi: 10.1002/14651858.CD012862.pub2.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
4 sites in 4 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing OMS721 (narsoplimab) in people with Thrombotic Microangiopathies and Atypical Hemolytic Uremic Syndrome, run by Omeros Corporation at 4 sites in 4 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 16 inclusion and 25 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 10 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 sites in United States, Lithuania, Poland, Taiwan. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 10 Dec 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Platelet Count (10^9 Platelets/L) Change From Baseline at Week 26 (time frame: Week 26). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03205995, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Dec 2025.