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BAY2599023

Phase 1

Hemophilia A | Small molecule | Hematology |Bayer AG|Trials Updated: Sep 23, 2026

BAY2599023 target and mechanism

ModalitySmall molecule

Also known as BAY2599023 (DTX201)

Success Probability

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Market & Valuation

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Trial Design

UNCONTROLLEDDMC
Total Trials1
Total Enrollment11

FDA Designations

No designations recorded

BAY2599023 clinical trials

BAY2599023 · 1 trial · 1 indication

Phase 1 1
NCT03588299Study 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"Hemophilia A
COMPLETED11 Analytics
PHASE1COMPLETED
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"
Hemophilia AUnlock trial analytics

Study Endpoints

Primary Endpoints

Number of patients with adverse events (AEs), treatment-emergent adverse events (TEAEs), serious adverse events (SAEs) and AEs/SAEs of special interest
Up to 5 years.

Secondary Endpoints

Expression pattern of FVIII activity.
Up to 5 years
Proportion of patients in the respective dose step, that reached an expression of FVIII above 5%
At 6 months and 12 months following the IV administration of BAY2599023
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Study Design & Arms

AllocationNA
MaskingNONE
ModelSINGLE_GROUP
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
BAY2599023 / (DTX201)EXPERIMENTALAdult patients with severe hemophilia A, who have been previously treated with FVIII products

Interventions

NameTypeDescription
BAY2599023 (DTX201)DRUGSingle escalating doses with 4 dose steps; Single intravenous (IV) administration.
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Eligibility Criteria

Age Range18 Years to N/A
SexMALE
Healthy VolunteersNo
Study Sites13

Inclusion Criteria: * 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 prophylaxi...

Countries:United StatesBulgariaFranceGermanyNetherlandsUnited Kingdom
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Recent Changes (Last 90 Days)

HIGHSep 23, 2026NCT03588299Status: ACTIVE_NOT_RECRUITING → COMPLETED
HIGHSep 23, 2026NCT03588299Status: ACTIVE_NOT_RECRUITING → COMPLETED
HIGHSep 23, 2026NCT03588299Status: ACTIVE_NOT_RECRUITING → COMPLETED

Frequently asked questions about BAY2599023

What is BAY2599023?

BAY2599023 is an investigational gene therapy being developed by Bayer AG for severe hemophilia A. It delivers a healthy version of the factor VIII gene into the nucleus of liver cells using an altered, non-infectious adeno-associated virus (AAV) as a shuttle. It is a Phase 1 asset and has not been approved.

What is BAY2599023 used for in hemophilia A?

BAY2599023 is being studied as a treatment for severe hemophilia A, a bleeding disorder caused by a defective factor VIII gene. The therapy is designed to deliver a healthy copy of that gene into liver cells so the body can produce factor VIII. It is investigational and has not been approved for any use.

Who is developing BAY2599023?

BAY2599023 is developed by Bayer AG, which trades on the OTC market under the ticker BAYRY. Bayer sponsored the Phase 1 study of the therapy in severe hemophilia A. The asset is also referred to as BAY2599023 (DTX201).

What phase is BAY2599023 in?

BAY2599023 is in Phase 1 clinical development. Its single Phase 1 trial, NCT03588299, has been completed. The study enrolled 11 participants and was an uncontrolled, non-randomized, open-label study, so it did not include a placebo or comparator arm. The drug remains investigational.

What clinical trials is BAY2599023 in?

BAY2599023 has been evaluated in one Phase 1 trial, NCT03588299, titled a study to test the safety and how well patients with severe hemophilia A respond to treatment with BAY 2599023 (DTX 201). The trial is completed and enrolled 11 male participants aged 18 years and older across the United States, Bulgaria, France, Germany, the Netherlands, and the United Kingdom.

Is BAY2599023 the same as DTX201?

Yes. BAY2599023 is also known as DTX201, and the two names refer to the same investigational gene therapy for severe hemophilia A. Trial records list the asset as BAY 2599023 (DTX 201). Bayer AG is the developer behind the program.