A Study to Evaluate the Safety and Efficacy of ZS801 in Adult Hemophilia B Patients

A Non-randomized, Open-label, Dose-escalation, Phase I/II Study to Evaluate the Safety, Tolerability, Kinetics and Efficacy of a Single Intravenous Infusion of ZS801 in Hemophilia B Subjects With Endogenous FIX ≤2%.

A Study to Evaluate the Safety and Efficacy of ZS801 in Adult Hemophilia B Patients (NCT05641610) is a Phase 1 / Phase 2 interventional studying Hemophilia B, sponsored by Institute of Hematology & Blood Diseases Hospital, China. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.

About This Trial

What Stage of Research Is This?

Phase 1 trials test a new treatment for the first time in humans, focusing on safety, dosing, and how the body processes the drug. For Hemophilia B, a Phase 1 study typically enrolls a small number of participants — often healthy volunteers or patients who have exhausted standard treatment options. Phase 1 results determine whether a treatment moves into larger Phase 2 efficacy studies.

This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.

With a target enrollment of 21 participants, this is a small study — typical of early-phase research, rare-disease trials, or pilot studies designed to generate preliminary signal before a larger study is launched.

Who May Be Eligible (Plain English)

Who May Qualify: 1. Male ≥18 years of age; 2. Confirmed diagnosis of hemophilia B, and endogenous FIX ≤2%; 3. Have had ≥100 prior exposure days (EDs) to any recombinant and/or plasma-derived FIX protein products; 4. The subject had at least 3 or more bleeding events and/or chronic hemophilia arthritis in one or more joints in the previous 1 year requiring treatment with FIX; 5. Agree to use reliable barrier contraception and prohibition of sperm donation until 52 weeks after the administration of ZS801. 6. Subjects voluntarily participate and are fully informed, fully understand the research and can comply with the requirements of the research protocol, are willing to complete the research as planned, and voluntarily cooperate with the provision of biological samples for testing. Who Should NOT Join This Trial: 1. Hypersensitivity to any component of the study drug (including immunosuppressants) or a condition that can not use; 2. Inability to tolerate immunosuppressants or steroid drugs; 3. Have FIX inhibitor as assessed by laboratory, or documented history of FIX inhibitor; 4. Who have a history or are currently suffering from any of the following serious clinical diseases: 1. History of malignancy or current presence of any malignancy; 2. Have active autoimmune conditions (where your immune system attacks your own body); 3. Severe heart disease, including angina pectoris, myocardial infarction, heart failure, clinically significant congenital heart disease, heart valve disease, arrhythmia and atrioventricular block, etc.; 4. Have underlying liver disease or history of liver disease (such as portal hypertension, ascites, splenomegaly, esophageal varices, hepatic encephalopathy or hepatic fibrosis); 5. Have active hepatitis B infection (HBsAg positive) or active hepatitis C infection (HCVAb positive), or are currently receiving hepatitis B or hepatitis C antiviral therapy; 6. Diabetes mellitus that is poorly controlled after drug treatment; ...See full criteria on ClinicalTrials.gov Always talk to your doctor about whether this trial is right for you.

These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.

Original Eligibility Criteria

View original clinical language

Inclusion Criteria: 1. Male ≥18 years of age; 2. Confirmed diagnosis of hemophilia B, and endogenous FIX ≤2%; 3. Have had ≥100 prior exposure days (EDs) to any recombinant and/or plasma-derived FIX protein products; 4. The subject had at least 3 or more bleeding events and/or chronic hemophilia arthritis in one or more joints in the previous 1 year requiring treatment with FIX; 5. Agree to use reliable barrier contraception and prohibition of sperm donation until 52 weeks after the administration of ZS801. 6. Subjects voluntarily participate and are fully informed, fully understand the research and can comply with the requirements of the research protocol, are willing to complete the research as planned, and voluntarily cooperate with the provision of biological samples for testing. Exclusion Criteria: 1. Hypersensitivity to any component of the study drug (including immunosuppressants) or a condition that can not use; 2. Inability to tolerate immunosuppressants or steroid drugs; 3. Have FIX inhibitor as assessed by laboratory, or documented history of FIX inhibitor; 4. Who have a history or are currently suffering from any of the following serious clinical diseases: 1. History of malignancy or current presence of any malignancy; 2. Have active autoimmune disease; 3. Severe heart disease, including angina pectoris, myocardial infarction, heart failure, clinically significant congenital heart disease, heart valve disease, arrhythmia and atrioventricular block, etc.; 4. Have underlying liver disease or history of liver disease (such as portal hypertension, ascites, splenomegaly, esophageal varices, hepatic encephalopathy or hepatic fibrosis); 5. Have active hepatitis B infection (HBsAg positive) or active hepatitis C infection (HCVAb positive), or are currently receiving hepatitis B or hepatitis C antiviral therapy; 6. Diabetes mellitus that is poorly controlled after drug treatment; 7. Uncontrolled hypertension or hypotension; 5. laboratory values: 1. Hemoglobin\<110g/L; 2. Platelets\<100×10\^9/L; 3. AST, ALT, alkaline phosphatase\>2×ULN; 4. Total bilirubin\>1.5×ULN; 5. Creatinine\>ULN; 6. Albumin\<LLN; 7. HIV antibody positive or Treponema pallidum antibody positive. 6. Have AAV5 capsid neutralizing antibody titers \>1:5; 7. Those who have received clinical trials of gene therapy before screening, or have used FIX clinical trial drugs within 1 month, or participated in other drug/device clinical trials within 3 months, or plan to participate in other clinical trials during this study; 8. Those who have planned surgery within 52 weeks after the infusion; 9. Those who lost more than 400 mL of blood within 3 months before screening; 10. Those with epilepsy, history of mental illness (such as schizophrenia, depression, mania or anxiety) or obvious mental disorder, incapacitated or incapacitated by other reasons; 11. Patients with a history of drug abuse or alcoholism; 12. Investigators believe that subjects have poor compliance or are expected to be less likely to complete follow-up; 13. There are clinically significant diseases or other reasons that the researcher and/or collaborators consider unsuitable to participate in this researcher.

Treatments Being Tested

GENETIC

ZS801

A novel, bioengineered adeno-associated viral (AAV) vector carrying human factor IX variant. The dose levels are as follows: 2.0×10\^12vg/kg, 5.0×10\^12vg/kg, 1.0×10\^13vg/kg.

Locations (1)

Trial sites listed on ClinicalTrials.gov for this study. Site activation status can vary — confirm with the specific site before traveling for a screening visit.

Institute of Hematology & Blood Diseases Hospital

Tianjin, Tianjin Municipality, China

How to Talk to Your Doctor About This Trial

Bring the printable summary of this trial — including the NCT ID (NCT05641610), the sponsor (Institute of Hematology & Blood Diseases Hospital, China), and the key eligibility criteria — to your next appointment. Your doctor can review the inclusion and exclusion criteria against your medical history, lab values, and current treatments to assess whether you are likely to qualify. They can also help you weigh whether trial participation makes sense alongside your existing care plan.

Useful questions to walk through together: What does the trial protocol require beyond standard care? How long is the active treatment phase, and how long is follow-up? Are there study visits at sites I can reach? Who pays for the trial-specific procedures, and who pays for standard-of-care portions? See our 25 questions to ask about clinical trials guide for a more complete checklist.

Authoritative Sources

The official record for this trial lives on ClinicalTrials.gov — the federal registry maintained by the National Library of Medicine at NIH. For background on how this trial fits into the FDA approval pathway, see the FDA drug approval process. For oncology-specific guidance for patients considering trials, the National Cancer Institute publishes patient-oriented overviews. International trial registries are aggregated by the WHO ICTRP.

Frequently Asked Questions

What is the NCT05641610 clinical trial studying?

A non-randomized, open-label, dose-escalation, phase I/II study to evaluate the safety, tolerability, kinetics and efficacy of a single intravenous infusion of ZS801 in hemophilia B subjects with endogenous FIX ≤2%. The full protocol is registered on ClinicalTrials.gov and includes the primary outcome measures, eligibility criteria, and study endpoints.

Who can participate in NCT05641610?

Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.

How do I contact the trial site for NCT05641610?

Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.

Is participating in a clinical trial safe?

Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.

Where can I verify the data on this page?

Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.

How This Page Is Built

Every field on this page is pulled directly from the ClinicalTrials.gov API v2 — no estimates, no proxies. The plain-English eligibility translation is generated from the original protocol text and reviewed for fidelity to the underlying clinical criteria. The original clinical text remains visible in the collapsible section above so users and clinicians can verify the translation. Read the full methodology for the data pipeline and known limitations.

Source: ClinicalTrials.gov API v2 record for NCT05641610. Maintained by the National Library of Medicine at NIH. Public domain. Cite as: "TrialFinderData. NCT05641610. Data: ClinicalTrials.gov."

Medical disclaimer: This page is informational, not medical advice. Talk to your doctor about whether a clinical trial is right for you.

Last updated 2026-05-08 · Data from ClinicalTrials.gov.