Hemophilia ANCT06273865
Version Testing of EnzySystem Version A for Hemophilia A
An observational study of Hemophilia A, run by Radboud University Medical Center at 2 sites in Netherlands.
Trial summary
Background of the study: To measure blood clotting, blood is taken from a vein. This blood is processed in the laboratory and then tested. A new device has been developed that requires only a very small volume of blood (5-10 drops of blood) to perform the laboratory tests. Read more about this study
- Who is it for?
- Ages 20 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Hemophilia A
- What is being tested?
- Several assays
- How many people
- 40 participants
- Where
- 2 sitesNetherlands
- Study dates
- 29 May 2024to 1 May 2026
- Phase
- Observational
- Are there results?
- None posted in the registry
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 20 to 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: The study population consists of healthy volunteers who respond to an advertisement at the Noviotech campus in Nijmegen Hemophilia A patients are recruited from the Hemophilia Treatment Center (HTC) Nijmegen-Eindhoven-Maastricht (NEM) (location Radboudumc).
Who may be able to join
- Healthy volunteers:
- Age between 20 to 70 years old (equally distributed over the age range)
- 7 volunteers 20-40 years old
- 7 volunteers 40-60 years old
- 6 volunteers 60+ years old
- Hemophilia A patients:
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- Diagnosed with mild (FVIII activity levels 5-40%), moderate (FVIII activity levels 1-5%) or severe hemophilia A (FVIII activity levels <1%)
- Medication
- On demand treatment
- Washout of medication of at least 24 hours after treatment with short half life (SHL) replacement therapy
- Washout of medication of at least 72 hours after treatment with extended half life (EHL) replacement therapy
- Age 20-70 years old
Who cannot join
- A healthy volunteer who meets any of the following criteria will be excluded from participation in this study:
- use of anticoagulants or platelet antagonists (aspirin or any TAR);
- known allergy to stainless steel;
- trauma or surgery within the last two weeks;
- pregnancy;
- use of:
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- NSAIDs;
- antimicrobial medication;
- thyroid inhibitors; or SSRI's. A hemophilia A patient who meets any of the following criteria will be excluded from participation in this study:
- use of anticoagulants or platelet antagonists (aspirin or any TAR);
- known allergy to stainless steel;
- trauma or surgery within the last two weeks;
- a bleeding episode within the last two weeks;
- clinical indication of liver cirrhosis (echographic indication, enlarged spleen, decreased platelet count);
- pregnancy;
- FVIII inhibitors;
- Signs of inflammation or infection
- use of:
- NSAIDs;
- antimicrobial medication;
- thyroid inhibitors or SSRI's;
- Emicizumab.
Trial locations and contacts
2 sites in 1 country.
Netherlands2 sites
Enzyre BV
Nijmegen, Gelderland
Radboud university medical center
Nijmegen, 6525 GA
About this study
Background of the study:
To measure blood clotting, blood is taken from a vein. This blood is processed in the laboratory and then tested. A new device has been developed that requires only a very small volume of blood (5-10 drops of blood) to perform the laboratory tests. The long-term goal is that this device can be used by a doctor or at home to quickly measure blood clotting. In this research we want to compare this new system with the standard methods - measurement in the laboratory - and evaluate whether the correct value is determined.
Read more
Objective of the study:
The primary objective of this study is to demonstrate that the EnzySystem HemA version A can record thrombin generation TG and quantify FVIII activity levels within a time frame of 60 min in fresh whole blood samples of healthy volunteers and patients with hemophilia A in the Enzyre laboratory (for healthy volunteers) and the Radboudumc (for patients with hemophilia A).
Study design:
This is a cross-sectional observational study. All participants are asked to fill a questionnaire prior to blood collection. The blood of healthy volunteers will be collected in an office of Enzyre BV, the blood of patients will be collected in the Radboudumc. Blood collection, by venepuncture, will be conducted by a Radboudumc research nurse or physician of the research team in both locations. In total, four blood tubes with citrate as anticoagulant will be drawn (a total of around 11 mL).
Study population:
The study population consists of 20 healthy volunteers: evenly distributed between male and female; ages spread over the range from 20 to 70 years old; recruited by Enzyre via advertisement. 20 Patients: 5 severe hemophilia A; 5 moderate hemophilia A; 10 mild hemophilia A; recruited from the Hemophilia Treatment Center (HTC) Nijmegen-Eindhoven-Maastricht (NEM) (location Radboudumc).
Primary study parameters/outcome of the study:
Demonstrate that the EnzySystem HemA version A can record TG and quantitative FVIII activity levels within a time frame of 60 min in fresh blood samples of healthy volunteers and patients with hemophilia A.
Secondary study parameters/outcome of the study (if applicable):
Secondary study parameters are composed whether the measured values comply with the desired assay specificity and accuracy.
Outcomes are analysed for equivalence compared to one-stage FVIII assay, FVIII chromogenic assay, thrombin generation via the Nijmegen Hemostasis Assay, and possibly via the Technoclone assay.
Is it possible to measure FVIII activity with the EnzySystem HemA version A in fresh blood samples of healthy volunteers and patients with hemophilia A, compared to the gold standard with;
- Precision in the normal range (60-140%): min. 30%
- Precision in the low range (3-10%): min. 50%
- Limit of Detection range min. 100 % FVIII activity
- Limit of Detection low range min. 3 % FVIII activity Is it possible to measure TG with the EnzySystem HemA version A in fresh blood samples of healthy volunteers and patients with hemophilia A, compared to the gold standard with;
- Precision in the normal range (60-140%) of control samples: min. 30%
- Precision in patient with hemophilia A: min. 50%
- Limit of Detection, high range > 400 nM thrombin activity
- Limit of Detection measured with Plasma, low range < 50 nM thrombin
Other study parameters All samples will also be tested for other hemostasis specific parameters as these parameters may affect a proper measurement of both FVIII activity and Thrombin Generation. The following parameters will be measured in plasma obtained from the whole blood vacutainers. Moreover, left over samples (plasma) will eventually be used to develop other coagulation related parameters.
- von Willebrand Factor antigen levels
- von Willebrand Factor ristocetin activity levels
- Prothrombin Fragment 1+2 levels
- ADAMTS13 activity
- FVIII antigen levels
- blood group
- Conditions
- Hemophilia A
- Being tested
- Several assays
- Keywords
- Diagnostic, Point of care, Thrombin generation, Factor VIII
- Medical subject headings
- Hemophilia A, Disease
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Several assaysDiagnostic test
Standard blood draw by venipuncture is performed in all study participants to collect blood samples in four 2.7 mL citrated blood tubes. Tube one is a dummy tube and is discarded. Tube two is used for the FVIII activity and thrombin generation assay on the EnzySystem. Tube three is used to perform conventional FVIII activity and thrombin generation assays. Tube four is used for duplicate measurements of the conventional assays and measurement of prothrombin F1+2 antigen levels, ADAMTS13 activity, FVIII antigen, VWF (von Willebrand Factor) antigen and von Willebrand ristocetin cofactor activity levels.
| Study group | Role | What they receive |
|---|---|---|
| Healthy volunteers | Not described Receives: Diagnostic Test: Several assays | |
| Hemophilia A patient | Not described Receives: Diagnostic Test: Several assays |
What is being measured
The primary outcome is the main question the study is designed to answer.
Time between venipuncture and EnzySystem assay results
Time is measured between venipuncture, start of the EnzySystem FVIII activity and thrombin generation assay, and assay results
Measured: All measurements with the EnzySystem will be performed <2 hours of drawing blood
Secondary outcomes (2)
Validity of EnzySystem FVIII activity results
Comparison of the FVIII activity results obtained with the EnzySystem and with conventional (one-stage and chromogenic) assays
Measured: All steps until freezing of the plasma should take place within two hours after venipuncture
Validity of EnzySystem thrombin generation results
Comparison of the thrombin generation results obtained with the EnzySystem and with conventional assays
Measured: All steps until freezing of the plasma should take place within two hours after venipuncture
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Feb 2024
- Study start29 May 2024
- Primary completion1 Mar 2026 (estimated)
- Study completion1 May 2026 (estimated)
Why it stopped: Performing interim analysis before continuing with next center
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Hemophilia AStudies 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
- Observational
- Observational model
- Cohort
- Time perspective
- Cross-sectional
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Radboud University Medical Center
- Sponsor type
- University, hospital or other
- Collaborators
- Enzyre B.V.
- Responsible party
- Sponsor
- Investigators
- Saskia Schols, PhD, Principal investigator, Radboud University Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06273865
- Sponsor's protocol ID
- HEMSTOL77
- Status last verified
- Aug 2024
- First submitted
- 15 Feb 2024
- Last updated
- 15 Aug 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 15 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Version Testing of EnzySystem Version A for Hemophilia A
- ClinicalTrials.gov ID
- NCT06273865
- Acronym / sponsor ID
- HEMSTOL77
- Conditions
- Hemophilia A
- Keywords
- Diagnostic, Point of care, Thrombin generation, Factor VIII
- Study type
- Observational
- Recruitment status
- SuspendedReason stopped: Performing interim analysis before continuing with next center
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- Radboud University Medical CenterUniversity, hospital or other
- Collaborators
- Enzyre B.V.
- Study start
- 29 May 2024 (actual)
- Primary completion
- 1 Mar 2026 (estimated)
- Study completion
- 1 May 2026 (estimated)
- First posted
- 23 Feb 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Background of the study:
To measure blood clotting, blood is taken from a vein. This blood is processed in the laboratory and then tested. A new device has been developed that requires only a very small volume of blood (5-10 drops of blood) to perform the laboratory tests. The long-term goal is that this device can be used by a doctor or at home to quickly measure blood clotting. In this research we want to compare this new system with the standard methods - measurement in the laboratory - and evaluate whether the correct value is determined.
Objective of the study:
The primary objective of this study is to demonstrate that the EnzySystem HemA version A can record thrombin generation TG and quantify FVIII activity levels within a time frame of 60 min in fresh whole blood samples of healthy volunteers and patients with hemophilia A in the Enzyre laboratory (for healthy volunteers) and the Radboudumc (for patients with hemophilia A).
Study design:
This is a cross-sectional observational study. All participants are asked to fill a questionnaire prior to blood collection. The blood of healthy volunteers will be collected in an office of Enzyre BV, the blood of patients will be collected in the Radboudumc. Blood collection, by venepuncture, will be conducted by a Radboudumc research nurse or physician of the research team in both locations. In total, four blood tubes with citrate as anticoagulant will be drawn (a total of around 11 mL).
Study population:
The study population consists of 20 healthy volunteers: evenly distributed between male and female; ages spread over the range from 20 to 70 years old; recruited by Enzyre via advertisement. 20 Patients: 5 severe hemophilia A; 5 moderate hemophilia A; 10 mild hemophilia A; recruited from the Hemophilia Treatment Center (HTC) Nijmegen-Eindhoven-Maastricht (NEM) (location Radboudumc).
Primary study parameters/outcome of the study:
Demonstrate that the EnzySystem HemA version A can record TG and quantitative FVIII activity levels within a time frame of 60 min in fresh blood samples of healthy volunteers and patients with hemophilia A.
Secondary study parameters/outcome of the study (if applicable):
Secondary study parameters are composed whether the measured values comply with the desired assay specificity and accuracy.
Outcomes are analysed for equivalence compared to one-stage FVIII assay, FVIII chromogenic assay, thrombin generation via the Nijmegen Hemostasis Assay, and possibly via the Technoclone assay.
Is it possible to measure FVIII activity with the EnzySystem HemA version A in fresh blood samples of healthy volunteers and patients with hemophilia A, compared to the gold standard with;
- Precision in the normal range (60-140%): min. 30%
- Precision in the low range (3-10%): min. 50%
- Limit of Detection range min. 100 % FVIII activity
- Limit of Detection low range min. 3 % FVIII activity Is it possible to measure TG with the EnzySystem HemA version A in fresh blood samples of healthy volunteers and patients with hemophilia A, compared to the gold standard with;
- Precision in the normal range (60-140%) of control samples: min. 30%
- Precision in patient with hemophilia A: min. 50%
- Limit of Detection, high range > 400 nM thrombin activity
- Limit of Detection measured with Plasma, low range < 50 nM thrombin
Other study parameters All samples will also be tested for other hemostasis specific parameters as these parameters may affect a proper measurement of both FVIII activity and Thrombin Generation. The following parameters will be measured in plasma obtained from the whole blood vacutainers. Moreover, left over samples (plasma) will eventually be used to develop other coagulation related parameters.
- von Willebrand Factor antigen levels
- von Willebrand Factor ristocetin activity levels
- Prothrombin Fragment 1+2 levels
- ADAMTS13 activity
- FVIII antigen levels
- blood group
Study design
- Observational model
- Cohort
- Time perspective
- Cross-sectional
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Healthy volunteers | – | Diagnostic Test: Several assays |
| Hemophilia A patient | – | Diagnostic Test: Several assays |
Who may qualify
- Ages
- 20 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- The study population consists of healthy volunteers who respond to an advertisement at the Noviotech campus in Nijmegen Hemophilia A patients are recruited from the Hemophilia Treatment Center (HTC) Nijmegen-Eindhoven-Maastricht (NEM) (location Radboudumc).
Key inclusion criteria (12 listed)
- Age between 20 to 70 years old (equally distributed over the age range)
- 7 volunteers 20-40 years old
- 7 volunteers 40-60 years old
- 6 volunteers 60+ years old
- Diagnosed with mild (FVIII activity levels 5-40%), moderate (FVIII activity levels 1-5%) or severe hemophilia A (FVIII activity levels <1%)
Key exclusion criteria (22 listed)
- A healthy volunteer who meets any of the following criteria will be excluded from participation in this study:
- use of anticoagulants or platelet antagonists (aspirin or any TAR);
- known allergy to stainless steel;
- trauma or surgery within the last two weeks;
- pregnancy;
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 |
|---|---|---|
| Several assaysStandard blood draw by venipuncture is performed in all study participants to collect blood samples in four 2.7 mL citrated blood tubes. Tube one is a dummy tube and is discarded. Tube two is used for the FVIII activity and thrombin generation assay on the EnzySystem. Tube three is used to perform conventional FVIII activity and thrombin generation assays. Tube four is used for duplicate measurements of the conventional assays and measurement of prothrombin F1+2 antigen levels, ADAMTS13 activity, FVIII antigen, VWF (von Willebrand Factor) antigen and von Willebrand ristocetin cofactor activity levels. | Diagnostic test | Healthy volunteers, Hemophilia A patient |
Primary outcome
Time between venipuncture and EnzySystem assay results
Time frame: All measurements with the EnzySystem will be performed <2 hours of drawing blood
Time is measured between venipuncture, start of the EnzySystem FVIII activity and thrombin generation assay, and assay results
2 secondary outcomes
Validity of EnzySystem FVIII activity results
Time frame: All steps until freezing of the plasma should take place within two hours after venipuncture
Validity of EnzySystem thrombin generation results
Time frame: All steps until freezing of the plasma should take place within two hours after venipuncture
Results and safety
Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Aug 2025.
- 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.
Saskia Schols, PhD principal investigator
Radboud University Medical Center
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Hemophilia A, run by Radboud University Medical Center at 2 sites in Netherlands.
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 12 inclusion and 22 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: paused, as of the sponsor's last update on 15 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Netherlands. 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.
Are results available for this study?
Results are not available in the source record.
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?
Time between venipuncture and EnzySystem assay results (time frame: All measurements with the EnzySystem will be performed <2 hours of drawing blood). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 15 Aug 2025.