NCT03369444 (FIX-GT) is a Phase 1, PHASE2 clinical trial of FLT180a in Hemophilia B, sponsored by University College, London.

Who is sponsoring NCT03369444?

NCT03369444 is sponsored by University College, London.

What drugs are being tested in NCT03369444?

Interventions in NCT03369444: FLT180a.

What condition does NCT03369444 study?

NCT03369444 studies Hemophilia B.

Is NCT03369444 still recruiting?

NCT03369444 is currently terminated. Last updated 2 December 2022.

Are results published for NCT03369444?

Yes — primary outcome results have been posted to ClinicalTrials.gov. See the outcomes section above for details.

Last reviewed 2022-12-02 · How we verify

NCT03369444: FIX-GT

Name: Drug Landscape Pharmaceutical Database
Creator: Drug Landscape
Published: 2026-01-01
License: https://creativecommons.org/licenses/by/4.0/

A Factor IX Gene Therapy Study (FIX-GT)

Terminated Phase 1, PHASE2 Results posted Last updated 2 December 2022

What this trial tests

Phase 1, PHASE2 trial testing FLT180a in Hemophilia B in 10 participants. Terminated before completion.

Timeline

5 December 2017

Primary endpoint
20 October 2020

20 October 2020

Quick facts

Lead sponsor	University College, London
Phase	Phase 1, PHASE2
Status	Terminated
Study type	INTERVENTIONAL
Allocation	non randomized
Design	sequential
Masking	none
Primary purpose	treatment
Enrollment	10
Start date	5 December 2017
Primary completion	20 October 2020
Estimated completion	20 October 2020
Sites	11 locations across Italy, Ireland, United States, United Kingdom

Drugs / interventions tested

FLT180a — full drug profile →

Conditions studied

Hemophilia B — all drugs for Hemophilia B →

Sponsor

University College, London

Who can join

18 and older, male only, with Hemophilia B. Patients with the condition only — healthy volunteers not accepted.

Results — posted to ClinicalTrials.gov

Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.

Frequency and Severity of Treatment-emergent Adverse Events (TEAEs) (Safety) Primary · From Day 0 (first dose of FLT180a) until week 26 post infusion (up to 26 weeks)

Safety as assessed by the reporting of AEs according to Common Terminology Criteria for Adverse Events (CTCAE) v5.0

Number of TEAEs

Group	Value	95% CI
FLT180a First Dose	11
FLT180a Second Dose	37
FLT180a Third Dose	25
FLT180a Fourth Dose	108

Serious TEAEs

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	6
FLT180a Third Dose	4
FLT180a Fourth Dose	5

FLT180a-related TEAEs

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	13
FLT180a Third Dose	4
FLT180a Fourth Dose	10

Serious FLT180a-related TEAEs

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	3
FLT180a Third Dose	4
FLT180a Fourth Dose	4

Number of Participants With FIX Activity Response Primary · From screening until week 26 post infusion (Up to 38 weeks)

The proportion of participants at the terminal dose (1.3 x 10e\^12 vg/kg) achieving clinical FIX response and proportion of patients achieving normalised FIX response at Week 26. A clinical FIX response is defined as achieving a FIX activity of 5% to 150%. Normalised FIX response is defined as achieving FIX activity in the normal range (50-150%).

Clinical FIX Responders (≥5% and ≤150% of Normal)

Group	Value	95% CI
FLT180a Fourth Dose	2

Normalised FIX Responders (≥50% and ≤150% of Normal)

Group	Value	95% CI
FLT180a Fourth Dose	2

Number of Participants With a Change From Baseline or Abnormal Finding From Routine Safety Assessments Secondary · From screening until week 26 post infusion (Up to 38 weeks)

Safety as assessed by reporting of abnormal or change from baseline findings from routine safety assessments including, laboratory assessments, ECG, physical exam and liver ultrasound.

Haemoglobin

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	1
FLT180a Third Dose	0
FLT180a Fourth Dose	2

Leukocytes (10e9/L0

Group	Value	95% CI
FLT180a First Dose	1
FLT180a Second Dose	0
FLT180a Third Dose	2
FLT180a Fourth Dose	1

Lymphocytes count decreased (10e9/L)

Group	Value	95% CI
FLT180a First Dose	1
FLT180a Second Dose	2
FLT180a Third Dose	2
FLT180a Fourth Dose	3

Lymphocytes count increased (10e9/L)

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	0
FLT180a Third Dose	0
FLT180a Fourth Dose	2

Neutrophils (10e9/L)

Group	Value	95% CI
FLT180a First Dose	1
FLT180a Second Dose	0
FLT180a Third Dose	0
FLT180a Fourth Dose	1

Platelets (10e9/L)

Group	Value	95% CI
FLT180a First Dose	1
FLT180a Second Dose	1
FLT180a Third Dose	1
FLT180a Fourth Dose	0

Basophils (10e9/L)

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	0
FLT180a Third Dose	0
FLT180a Fourth Dose	0

Eosinophils (10e9/L)

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	0
FLT180a Third Dose	0
FLT180a Fourth Dose	0

FIX Concentrate Usage Secondary · Baseline and Post Dose (Day15 post infusion to Week26/End of Study)

Change from baseline in FIX concentrate consumption.

Annualised Total Units (IU) of FIX Concentrate Consumption at Baseline

Group	Value	95% CI
FLT180a First Dose	501500	± 300520.38
FLT180a Second Dose	1219000	± 72124.89
FLT180a Third Dose	968000	± 14142.14
FLT180a Fourth Dose	350947.5	± 112653.53

Annualised Total Total Units (IU) of FIX Concentrate Consumption Post-Dose (Day 15 to Week 26/EOS)

Group	Value	95% CI
FLT180a First Dose	0	± 0
FLT180a Second Dose	0	± 0
FLT180a Third Dose	0	± 0
FLT180a Fourth Dose	0	± 0

Bleeding Frequency Secondary · Baseline and Post-Dose (Day 15 to Week 26/EOS)

Change from baseline in annualised bleeding rate (ABR)

ABR at Baseline (over last 3 years)

Group	Value	95% CI
FLT180a First Dose	4.665	± 0.9405
FLT180a Second Dose	4.330	± 4.2426
FLT180a Third Dose	1.0	± 1.4142
FLT180a Fourth Dose	2.335	± 1.1208

ABR at Post-Dose (Day 15 to WEek 26/EOS)

Group	Value	95% CI
FLT180a First Dose	2.175	± 3.0759
FLT180a Second Dose	0	± 0
FLT180a Third Dose	2.160	± 3.0547
FLT180a Fourth Dose	0.548	± 1.0950

Immune Response - Development of Inhibitors Secondary · Week 1, week 2, week 3, week 6, week 9, week 12, week 16, week 20 and week 26/EOS post infusion

Immune response to the human FIX transgene product (i.e., development of FIX neutralising antibodies referred to as inhibitors) will be assessed by measurement of the level of inhibitors.

Week 1

Group	Value	95% CI
FLT180a First Dose	1
FLT180a Second Dose	0
FLT180a Third Dose	2
FLT180a Fourth Dose	0
FLT180a First Dose	1
FLT180a Second Dose	2
FLT180a Third Dose	0
FLT180a Fourth Dose	4

Week 2

Group	Value	95% CI
FLT180a First Dose	2
FLT180a Second Dose	0
FLT180a Third Dose	2
FLT180a Fourth Dose	0
FLT180a First Dose	0
FLT180a Second Dose	2
FLT180a Third Dose	0
FLT180a Fourth Dose	4

Week 3

Group	Value	95% CI
FLT180a First Dose	1
FLT180a Second Dose	0
FLT180a Third Dose	0
FLT180a Fourth Dose	0
FLT180a First Dose	1
FLT180a Second Dose	2
FLT180a Third Dose	2
FLT180a Fourth Dose	4

Week 6

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	0
FLT180a Third Dose	1
FLT180a Fourth Dose	0
FLT180a First Dose	2
FLT180a Second Dose	2
FLT180a Third Dose	1
FLT180a Fourth Dose	4

Week 9

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	0
FLT180a Third Dose	0
FLT180a Fourth Dose	0
FLT180a First Dose	2
FLT180a Second Dose	2
FLT180a Third Dose	2
FLT180a Fourth Dose	4

Week 12

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	0
FLT180a Third Dose	0
FLT180a Fourth Dose	0
FLT180a First Dose	2
FLT180a Second Dose	2
FLT180a Third Dose	2
FLT180a Fourth Dose	4

Week 16

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	0
FLT180a Third Dose	0
FLT180a Fourth Dose	0
FLT180a First Dose	2
FLT180a Second Dose	2
FLT180a Third Dose	2
FLT180a Fourth Dose	4

Week 20

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	0
FLT180a Third Dose	0
FLT180a Fourth Dose	0
FLT180a First Dose	2
FLT180a Second Dose	2
FLT180a Third Dose	2
FLT180a Fourth Dose	4

Viral Shedding Evaluated as Time to Unquantifiable Vector Genomes Secondary · From screening until time to unquantifiable results of vector genomes in all matrices, up to an average of 5.14 weeks

Serum and bodily secretions will be collected to assess clearance of vector genomes

Plasma

Group	Value	95% CI
FLT180a First Dose	1.355	± 1.1102
FLT180a Second Dose	1.715	± 0.6010
FLT180a Third Dose	1.425	± 1.0112
FLT180a Fourth Dose	1.750	± 0.6320

Saliva

Group	Value	95% CI
FLT180a First Dose	0.570	± 0.000
FLT180a Second Dose	2.570	± 0.6081
FLT180a Third Dose	1.355	± 1.1102
FLT180a Fourth Dose	2.143	± 0.9972

Semen

Group	Value	95% CI
FLT180a First Dose	2.285	± 0.2051
FLT180a Second Dose	3.070	± 0.0990
FLT180a Third Dose	2.640	± 0.7071
FLT180a Fourth Dose	3.750	± 1.0357

Stool

Group	Value	95% CI
FLT180a First Dose	2.930	± 0.7071
FLT180a Second Dose	4.290	± 1.4142
FLT180a Third Dose	5.140	± 1.4142
FLT180a Fourth Dose	3.788	± 0.5007

Urine

Group	Value	95% CI
FLT180a First Dose	1.355	± 1.1102
FLT180a Second Dose	2.070	± 0.0990
FLT180a Third Dose	2.140	± 0.0000
FLT180a Fourth Dose	1.178	± 0.7590

Endogenous FIX Production Secondary · From screening until week 26 post infusion

The proportion of patients achieving FIX activity at or above 5%, 15%, 30%, 40%, 50%, 70% and 150% of normal, at each scheduled visit, will be summarised by dose and overall.

FIX Activity ≥5% and ≤150% of Normal

Group	Value	95% CI
FLT180a First Dose	2
FLT180a Second Dose	1
FLT180a Third Dose	2
FLT180a Forth Dose	2

FIX Activity ≥15% and ≤150% of Normal

Group	Value	95% CI
FLT180a First Dose	2
FLT180a Second Dose	1
FLT180a Third Dose	1
FLT180a Forth Dose	2

FIX Activity ≥30% and ≤150% of Normal

Group	Value	95% CI
FLT180a First Dose	2
FLT180a Second Dose	1
FLT180a Third Dose	1
FLT180a Forth Dose	2

FIX Activity ≥40% and ≤150% of Normal

Group	Value	95% CI
FLT180a First Dose	2
FLT180a Second Dose	1
FLT180a Third Dose	1
FLT180a Forth Dose	2

FIX Activity ≥50% and ≤150% of Normal

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	1
FLT180a Third Dose	1
FLT180a Forth Dose	2

FIX Activity ≥70% and ≤150% of Normal

Group	Value	95% CI
FLT180a First Dose	0
FLT180a Second Dose	1
FLT180a Third Dose	0
FLT180a Forth Dose	1

FIX Activity ≥5% of Normal

Group	Value	95% CI
FLT180a First Dose	2
FLT180a Second Dose	2
FLT180a Third Dose	2
FLT180a Forth Dose	4

FIX Activity ≥15% of Normal

Group	Value	95% CI
FLT180a First Dose	2
FLT180a Second Dose	2
FLT180a Third Dose	1
FLT180a Forth Dose	4

Change From Baseline in FIX Activity as a Percentage of Normal Values Secondary · Week 26/EOS

Absolute change from baseline in FIX production (% FIX activity) at week 26/EOS will be summarised.

Group	Value	95% CI
FLT180a First Dose	40	± 7.07
FLT180a Second Dose	155.5	± 157.68
FLT180a Third Dose	32.0	± 41.01
FLT180a Fourth Dose	129.3	± 65.7

Adverse events — posted to ClinicalTrials.gov

Time frame: From consent to Week 26 post dose/End of Study visit or early withdrawal of patient (up to 38 weeks).. Reporting threshold: 0%. Adverse-event reports describe events observed during the trial — not all are caused by the drug.

FLT180a First Dose

Serious: 0/2 (0%)

Deaths: 0/2

FLT180a Second Dose

Serious: 2/2 (100%)

Deaths: 0/2

FLT180a Third Dose

Serious: 2/2 (100%)

Deaths: 0/2

FLT180a Forth Dose

Serious: 3/4 (75%)

Deaths: 0/4

Serious adverse events (8 terms)

Reaction	System	FLT180a First Dose	FLT180a Second Dose	FLT180a Third Dose	FLT180a Forth Dose
Transaminitis	Investigations	—	—	—	—
Increased ALT	Investigations	—	—	—	—
Abdominal pain upper	Gastrointestinal disorders	—	—	—	—
Raised Troponin	Investigations	—	—	—	—
Raised Amylase	Investigations	—	—	—	—
Chest Sepsis (no more information)	Infections and infestations	—	—	—	—
Drop in Factor IX	Investigations	—	—	—	—
Tacrolimus Toxicity	Injury, poisoning and procedural complications	—	—	—	—

Other adverse events (80 terms — click to expand)

Reaction	System	FLT180a First Dose	FLT180a Second Dose	FLT180a Third Dose	FLT180a Forth Dose
Headache	Nervous system disorders	—	—	—	—
Transaminases increased	Investigations	—	—	—	—
Muscle spasms	Musculoskeletal and connective tissue disorders	—	—	—	—
Diarrhoea	Gastrointestinal disorders	—	—	—	—
Fatigue	General disorders	—	—	—	—
Tremor	Nervous system disorders	—	—	—	—
Alanine aminotransferase increased	Investigations	—	—	—	—
Blood creatine phosphokinase increased	Investigations	—	—	—	—
Blood lactate dehydrogenase increased	Investigations	—	—	—	—
Coagulation factor IX level increased	Investigations	—	—	—	—
Arthralgia	Musculoskeletal and connective tissue disorders	—	—	—	—
Myalgia	Musculoskeletal and connective tissue disorders	—	—	—	—
Nausea	Gastrointestinal disorders	—	—	—	—
Rhinitis	Infections and infestations	—	—	—	—
Paraesthesia	Nervous system disorders	—	—	—	—
Oropharyngeal pain	Respiratory, thoracic and mediastinal disorders	—	—	—	—
Cushingoid	Endocrine disorders	—	—	—	—
Decreased appetite	Metabolism and nutrition disorders	—	—	—	—
Aspartate aminotransferase increased	Investigations	—	—	—	—
Amylase increased	Investigations	—	—	—	—
Blood bilirubin increased	Investigations	—	—	—	—
Blood glucose increased	Investigations	—	—	—	—
Coagulation factor IX level decreased	Investigations	—	—	—	—
Drug level increased	Investigations	—	—	—	—
Troponin increased	Investigations	—	—	—	—
Pain in extremity	Musculoskeletal and connective tissue disorders	—	—	—	—
Back pain	Musculoskeletal and connective tissue disorders	—	—	—	—
Joint effusion	Musculoskeletal and connective tissue disorders	—	—	—	—
Joint stiffness	Musculoskeletal and connective tissue disorders	—	—	—	—
Musculoskeletal pain	Musculoskeletal and connective tissue disorders	—	—	—	—
Dyspepsia	Gastrointestinal disorders	—	—	—	—
Abdominal pain	Gastrointestinal disorders	—	—	—	—
Abdominal pain upper	Gastrointestinal disorders	—	—	—	—
Abdominal distension	Gastrointestinal disorders	—	—	—	—
Constipation	Gastrointestinal disorders	—	—	—	—
Eructation	Gastrointestinal disorders	—	—	—	—
Gingival pain	Gastrointestinal disorders	—	—	—	—
Haemorrhoids	Gastrointestinal disorders	—	—	—	—
Toothache	Gastrointestinal disorders	—	—	—	—
Vomiting	Gastrointestinal disorders	—	—	—	—

Most-reported serious reactions: Transaminitis, Increased ALT, Abdominal pain upper, Raised Troponin, Raised Amylase, Chest Sepsis (no more information), Drop in Factor IX, Tacrolimus Toxicity.

Data from ClinicalTrials.gov NCT03369444 adverse events section.

Sponsor's own description

Severe haemophilia B (HB) is a bleeding disorder where a protein made by the body to help make blood clot is either partly or completely missing. This protein is called a clotting factor; with severe haemophilia B, levels of clotting factor IX (FIX) (nine) are very low and affected individuals can suffer life threatening bleeding episodes. HB mainly affects boys and men (normally one in every 30,000 males). Current treatment for HB involves intravenous infusions of factor IX as regular treatment (Prophylaxis) or 'on demand'. On demand treatment is highly effective at stopping bleeding but cannot fully reverse long-term damage that follows after a bleed. Regular treatment can prevent bleeding, however can be invasive for patients and also expensive. This research study aims to test the safety and effectiveness of a gene therapy which produces Factor IX protein in the body. The gene will be given using an inactivated virus called "the vector" ( FLT180a), in a single infusion. The vector has been developed from a virus known as an adeno- associated virus, that has been changed so that it is unable to cause a viral infection in humans. This "inactivated" virus is further altered to carry the Factor IX gene and to make its way within liver cells where Factor IX protein is normally made. Up to three different doses cohorts of FLT180a will be tested, in up to 24 patients with severe haemophilia B. Patients will be recruited from haemophilia centres in the EU and US. Patients will be in the trial for approximately 40 weeks and will undergo procedures including physical examinations, bloods tests, ECGs and liver ultrasounds.

Publications & conference data

8 peer-reviewed publications reference this trial (live from Europe PMC):

Viral vector platforms within the gene therapy landscape.
Bulcha JT, Wang Y, Ma H, Tai PWL, et al · · 2021 · cited 899× · PMID 33558455 · DOI 10.1038/s41392-021-00487-6
Update on clinical gene therapy for hemophilia.
Perrin GQ, Herzog RW, Markusic DM. · · 2019 · cited 128× · PMID 30559260 · DOI 10.1182/blood-2018-07-820720
rAAV immunogenicity, toxicity, and durability in 255 clinical trials: A meta-analysis.
Shen W, Liu S, Ou L. · · 2022 · cited 123× · PMID 36389770 · DOI 10.3389/fimmu.2022.1001263
Phase 1-2 Trial of AAVS3 Gene Therapy in Patients with Hemophilia B.
Chowdary P, Shapiro S, Makris M, Evans G, et al · · 2022 · cited 115× · PMID 35857660 · DOI 10.1056/nejmoa2119913
Adeno-Associated Virus Gene Therapy for Hemophilia.
Samelson-Jones BJ, George LA. · · 2023 · cited 97× · PMID 36103998 · DOI 10.1146/annurev-med-043021-033013
Durability of transgene expression after rAAV gene therapy.
Muhuri M, Levy DI, Schulz M, McCarty D, et al · · 2022 · cited 94× · PMID 35283274 · DOI 10.1016/j.ymthe.2022.03.004
Testing preexisting antibodies prior to AAV gene transfer therapy: rationale, lessons and future considerations.
Mendell JR, Connolly AM, Lehman KJ, Griffin DA, et al · · 2022 · cited 87× · PMID 35356756 · DOI 10.1016/j.omtm.2022.02.011
A Molecular Revolution in the Treatment of Hemophilia.
Butterfield JSS, Hege KM, Herzog RW, Kaczmarek R. · · 2020 · cited 76× · PMID 31843450 · DOI 10.1016/j.ymthe.2019.11.006

Verify or expand the search:

Other trials of FLT180a

Trials testing the same drug.

NCT03641703 — A Long-Term Follow-Up Study of Haemophilia B Patients Who Have Undergone Gene Therapy · Phase 1, PHASE2 · terminated

Other recruiting trials for Hemophilia B

Currently open trials in the same condition.

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NCT06399289 — Recombinant Fusion Protein Linking Coagulation Factor IX With Albumin (rIX-FP) in Chinese Subjects With Hemophilia B Pre · Phase 3 · active not recruiting

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Verify against primary sources

ClinicalTrials.gov — authoritative US registry record
WHO ICTRP — international registry index
EU Clinical Trials Register
Sponsor press releases (Google)

Data sources for this page

Trial protocol + status: ClinicalTrials.gov NCT03369444 (US National Library of Medicine, public domain)
Publications: Europe PMC API search by NCT ID, retrieved 10 June 2026
Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
Sponsor: as reported to ClinicalTrials.gov by University College, London
Last refreshed: 2 December 2022

Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT03369444.

Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing

NCT03369444: FIX-GT

Quick facts

Drugs / interventions tested

Conditions studied

Sponsor

Who can join

Results — posted to ClinicalTrials.gov

Adverse events — posted to ClinicalTrials.gov

Serious adverse events (8 terms)

Sponsor's own description

Publications & conference data

Related trials

Other trials of FLT180a

Other recruiting trials for Hemophilia B

Other University College, London trials

Verify against primary sources