Hemophilia APhase 1/2NCT03588299
Study to Test the Safety and How Well Patients With Severe Hemophilia A Respond to Treatment With BAY 2599023 (DTX 201), a Drug Therapy That Delivers a Healthy Version of the Defective Factor VIII Gene Into the Nucleus of Liver Cells Using an Altered, Non-infectious Virus (AAV) as a "Shuttle"
A Phase 1/2 study testing BAY2599023 (DTX201) in people with Hemophilia A, run by Bayer at 13 sites in 6 countries.
Trial summary
In this study researchers want to gather more information about safety and effectiveness of BAY 2599023 (DTX201), a drug therapy that delivers the human factor VIII gene into the human body by use of a viral vector to treat the disease. Read more about this study
- Who is it for?
- Ages 18 years and older, men only
- Conditions the study is for
- Hemophilia A
- What is being tested?
- BAY2599023 (DTX201)
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 11 participants
- Where
- 13 sitesin 6 countries
- Study dates
- 7 Nov 2018to 15 Sep 2026
- Phase
- Phase 1/2
- 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 18 years and older
- Men only
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Males age 18 years or older.
- Confirmed diagnosis of hemophilia A as evidenced by their medical history with plasma FVIII activity levels < 1% of normal or at screening.
- Have >150 exposure days (EDs) to FVIII concentrates (recombinant or plasma-derived).
- If on prophylaxis, are required to be willing to stop prophylactic treatment at specified time points throughout the study or If on-demand: should have had > 4 bleeding events in the last 52 weeks
- Agree to use reliable barrier contraception.
Who cannot join
- History of allergic reaction to any FVIII product.
- Clinically relevant findings in the physical examination considered critical by the treating physician, including obesity with BMI > 35 kg/m*2
- Current evidence of measurable inhibitor against factor VIII, prior history of inhibitors to FVIII protein or clinical history suggestive of inhibitor.
- Evidence of active hepatitis B or C.
- Currently on antiviral therapy for hepatitis B or C.
- Significant underlying liver disease.
Show all 11Show fewer
- Serological evidence of HIV-1 or HIV-2 with CD4 counts ≤200/mm*3; HIV+ and stable participants with CD4 count >200/mm*3 and undetectable viral load are eligible to enroll.
- Detectable antibodies reactive with AAVhu37capsid.
- Participant with another bleeding disorder that is different from hemophilia A (e.g., von Willebrand disease, hemophilia B).
- Participated in a gene transfer trial within the last 52 weeks or in a clinical trial with an investigational product within the last 12 weeks.
- Known or suspected hypersensitivity or allergic reaction to trial product(s) or related FVIII products or any component of BAY2599023 (DTX201), or a contraindication to prednisolone
Trial locations and contacts
13 sites in 6 countries.
13 sites in 6 countries
Netherlands4 sites
Academisch Medisch Centrum (AMC)
Amsterdam, North Holland, 1105 AZ
Universitair Medisch Centrum Groningen
Groningen, Provincie Groningen, 9713 GZ
Erasmus Medisch Centrum
Rotterdam, South Holland, 3015 CE
University Medical Center Utrecht
Utrecht, Utrecht, 3584 CX
United States3 sites
C.S. Mott Children's Hospital - Hematology / Oncology
Ann Arbor, Michigan, 48109
Arkansas Children's Hospital - Hematology / Oncology
Little Rock, Arkansas, 72202
UW Health Carbone Cancer Center
Madison, Wisconsin, 53792
France2 sites
APHP-Hopital Necker Enfants malades
Paris, Île-de-France Region, 75015
CHU Rennes - Hopital Pontchaillou
Rennes, Brittany Region, 35033
Germany2 sites
Vivantes Klinikum im Friedrichshain
Berlin, State of Berlin, 10249
Universitätsklinikum des Saarlandes
Homburg, Saarland, 66421
Bulgaria1 site
SHATHD Spec. Hospi. for Active Treatm. of Haematol. Dis. EAD
Sofia, Sofia City Province, 1756
United Kingdom1 site
Manchester Royal Infirmary | Haematology
Manchester, Greater Manchester, M13 9WL
About this study
Official title: A Phase 1/2 Open-label Safety and Dose-finding Study of BAY2599023 (DTX201), an Adeno-associated Virus (AAV) hu37-mediated Gene Transfer of B-domain Deleted Human Factor VIII, in Adults With Severe Hemophilia A
In this study researchers want to gather more information about safety and effectiveness of BAY 2599023 (DTX201), a drug therapy that delivers the human factor VIII gene into the human body by use of a viral vector to treat the disease. By replacing the defective gene with a healthy copy the human body may produce clotting factor on its own. Hemophilia A is a bleeding disorder in which the human body does not have enough clotting factor VIII, a protein that controls bleeding. Researcher want to find the optimal dose of BAY 2599023 (DTX201) so that the body may produce enough clotting factor on its own.
- Conditions
- Hemophilia A
- Being tested
- BAY2599023 (DTX201)
- Keywords
- Severe hemophilia A (<1% FVIII activity), Factor VIII gene therapy
- Medical subject headings
- Hemophilia A
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
BAY2599023 (DTX201)Drug
Single escalating doses with 4 dose steps; Single intravenous (IV) administration.
| Study group | Role | What they receive |
|---|---|---|
| BAY2599023 / (DTX201) | Experimental | Adult patients with severe hemophilia A, who have been previously treated with FVIII products Receives: Drug: BAY2599023 (DTX201) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of patients with adverse events (AEs), treatment-emergent adverse events (TEAEs), serious adverse events (SAEs) and AEs/SAEs of special interest
Measured: Up to 5 years.
Secondary outcomes (2)
Expression pattern of FVIII activity.
Determined using both a one-stage assay and chromogenic assay.
Measured: Up to 5 years
Proportion of patients in the respective dose step, that reached an expression of FVIII above 5%
Measured: At 6 months and 12 months following the IV administration of BAY2599023
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Jul 2018
- Study start7 Nov 2018
- Primary completion15 Sep 2026
- Study completion15 Sep 2026
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.
- More trials run by BayerThe sponsor's other registered studies.
- 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 1/2
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 11 participants (actual)
Sponsor and investigators
- Lead sponsor
- Bayer
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- Ultragenix pharmaceutical
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03588299
- Sponsor's protocol ID
- 19429
- Other IDs
- 2023-505827-29-00, 2017-000806-39, 2017, 2023
- Status last verified
- 16 Sep 2026
- First submitted
- 6 Jul 2018
- Last updated
- 23 Sep 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No: Availability of this study's data will later be determined according to Bayer's commitment to the EFPIA/PhRMA "Principles for responsible clinical trial data sharing". This pertains to scope, timepoint and process of data access. As such, Bayer commits to sharing upon request from qualified researchers patient-level clinical trial data, study-level clinical trial data, and protocols from clinical trials in patients for medicines and indications approved in the US and EU as necessary for conducting legitimate research. This applies to data on new medicines and indications that have been approved by the EU and US regulatory agencies on or after January 01, 2014. Interested researchers can use www.vivli.org to request access to anonymized patient-level data and supporting documents from clinical studies to conduct research. Information on the Bayer criteria for listing studies and other relevant information is provided in the member section of the portal.
Study at a glance
From the registry record, last updated by the sponsor on 23 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 1/2 Open-label Safety and Dose-finding Study of BAY2599023 (DTX201), an Adeno-associated Virus (AAV) hu37-mediated Gene Transfer of B-domain Deleted Human Factor VIII, in Adults With Severe Hemophilia A
- ClinicalTrials.gov ID
- NCT03588299
- Acronym / sponsor ID
- 19429
- Conditions
- Hemophilia A
- Keywords
- Severe hemophilia A (<1% FVIII activity), Factor VIII gene therapy
- Phase
- Phase 1/2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 11 participants (actual)
- Lead sponsor
- BayerIndustry (pharma, biotech, devices)
- Collaborators
- Ultragenix pharmaceutical
- Study start
- 7 Nov 2018 (actual)
- Primary completion
- 15 Sep 2026 (actual)
- Study completion
- 15 Sep 2026 (actual)
- First posted
- 17 Jul 2018 (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.
In this study researchers want to gather more information about safety and effectiveness of BAY 2599023 (DTX201), a drug therapy that delivers the human factor VIII gene into the human body by use of a viral vector to treat the disease. By replacing the defective gene with a healthy copy the human body may produce clotting factor on its own. Hemophilia A is a bleeding disorder in which the human body does not have enough clotting factor VIII, a protein that controls bleeding. Researcher want to find the optimal dose of BAY 2599023 (DTX201) so that the body may produce enough clotting factor on its own.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| BAY2599023 / (DTX201) | Experimental | Drug: BAY2599023 (DTX201)Adult patients with severe hemophilia A, who have been previously treated with FVIII products |
Who may qualify
- Ages
- 18 years and older
- Sex
- Male only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Males age 18 years or older.
- Confirmed diagnosis of hemophilia A as evidenced by their medical history with plasma FVIII activity levels < 1% of normal or at screening.
- Have >150 exposure days (EDs) to FVIII concentrates (recombinant or plasma-derived).
- If on prophylaxis, are required to be willing to stop prophylactic treatment at specified time points throughout the study or If on-demand: should have had > 4 bleeding events in the last 52 weeks
- Agree to use reliable barrier contraception.
Key exclusion criteria (11 listed)
- History of allergic reaction to any FVIII product.
- Clinically relevant findings in the physical examination considered critical by the treating physician, including obesity with BMI > 35 kg/m*2
- Current evidence of measurable inhibitor against factor VIII, prior history of inhibitors to FVIII protein or clinical history suggestive of inhibitor.
- Evidence of active hepatitis B or C.
- Currently on antiviral therapy for hepatitis B or C.
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 |
|---|---|---|
| BAY2599023 (DTX201)Single escalating doses with 4 dose steps; Single intravenous (IV) administration. | Drug | BAY2599023 / (DTX201) |
Primary outcome
Number of patients with adverse events (AEs), treatment-emergent adverse events (TEAEs), serious adverse events (SAEs) and AEs/SAEs of special interest
Time frame: Up to 5 years.
2 secondary outcomes
Expression pattern of FVIII activity.
Time frame: Up to 5 years
Proportion of patients in the respective dose step, that reached an expression of FVIII above 5%
Time frame: At 6 months and 12 months following the IV administration of BAY2599023
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 23 Sep 2026.
- Individual participant dataSharing planned: No. Availability of this study's data will later be determined according to Bayer's commitment to the EFPIA/PhRMA "Principles for responsible clinical trial data sharing". This pertains to scope, timepoint and process of data access. As such, Bayer commits to sharing upon request from qualified researchers patient-level clinical trial data, study-level clinical trial data, and protocols from clinical trials in patients for medicines and indications approved in the US and EU as necessary for conducting legitimate research. This applies to data on new medicines and indications that have been approved by the EU and US regulatory agencies on or after January 01, 2014. Interested researchers can use www.vivli.org to request access to anonymized patient-level data and supporting documents from clinical studies to conduct research. Information on the Bayer criteria for listing studies and other relevant information is provided in the member section of the portal.
Related trials for Hemophilia A
RecruitingObservational study
The CACHE Study: Coronary Artery Care in HaEmophilia
Haemophilia, Cardiovascular Diseases
Active, not recruitingObservational study
A Study to Learn About the Study Medicine -Hympavzi in Congenital Hemophilia Patients Without Inhibitors in Japan.
Hemophilia A or B
RecruitingPhase 1/2
A Study to Evaluate the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Efficacy of NXT007 in Persons With Severe or Moderate Hemophilia A
Hemophilia A
Active, not recruitingPhase 3
A Study to Evaluate the Efficacy and Safety of Factor IX Gene Therapy With PF-06838435 in Adult Males With Moderately Severe to Severe Hemophilia B
Hemophilia B
Not yet recruiting
Safety of Intraosseous Anaesthesia in Children With Haemophilia
Haemophilia A, Haemophilia B
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.
13 sites in 6 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1/2 study testing BAY2599023 (DTX201) in people with Hemophilia A, run by Bayer at 13 sites in 6 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 5 inclusion and 11 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: finished, as of the sponsor's last update on 23 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 13 sites in Netherlands, United States, France, Germany, Bulgaria and 1 more country. 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 combined phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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?
Number of patients with adverse events (AEs), treatment-emergent adverse events (TEAEs), serious adverse events (SAEs) and AEs/SAEs of special interest (time frame: Up to 5 years.). 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 23 Sep 2026.