Pharmacokinetic, Efficacy and Safety of BT524 in Patients With Congenital Fibrinogen Deficiency

A Prospective, Open-label, Phase I/III Study Investigating Pharmacokinetic Properties of BT524 and Efficacy and Safety of BT524 in the Treatment and Prophylaxis of Bleeding in Patients With Congenital Fibrinogen Deficiency

This was a prospective, open-label, multicenter, phase I/III study investigating the 14-day single-dose pharmacokinetic and pharmacodynamic properties, efficacy and safety of BT524 following intravenous administration in the treatment or prophylaxis of bleeding in patients with congenital afibrinogenemia or severe congenital hypofibrinogenemia.

Study Overview

• Status: Completed
• Conditions: Congenital Afibrinogenemia; Congenital Hypofibrinogenemia
• Intervention / Treatment: Drug: BT524 (Part I); Drug: BT524 (Part II)

Detailed Description

The study was divided into two parts (Part I and Part II). Part I focused on the primary endpoint of the study, 14-day single-dose pharmacokinetics (PK) and 14-day single-dose pharmacodynamics (PD), as well as the assessment of maximum clot firmness (MCF) as a surrogate parameter for efficacy. Part I of the study was followed by Part II, which evaluated the efficacy and safety of single and repetitive administration of BT524 in patients undergoing on-demand prophylaxis (ODP) and/or on-demand treatment (ODT) for various bleeding events [e.g., elective surgery, spontaneous or post-traumatic major bleeding]. All patients who participated in the PK assessment (Part I) without severe post-administration complications ideally continued treatment with BT524 for ODP and/or ODT in Part II.

• Study Type: Interventional
• Enrollment (Actual): 67
• Phase: Phase 3

Contacts and Locations

Study Locations

• Bulgaria
  • Sofia, Bulgaria
    • Site 15
• Egypt
  • Cairo, Egypt
    • Site 11
• Germany
  • Frankfurt, Germany
    • Site 16
• Lebanon
  • Beirut, Lebanon
    • Site 01
• Tunisia
  • Sousse, Tunisia
    • Site 14
  • Tunis, Tunisia
    • Site12

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 1 second to 75 years (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Known congenital afibrinogenemia or severe congenital hypofibrinogenemia
• Plasma fibrinogen activity ≤ 0.5 g/l and antigen ≤ 0.5 g/l
• Male or female
• Age 0 to 75 years, with the first ten patients will be 18 years or older
• Presumed to be compliant with the study procedures and to terminate the study as scheduled
• Willing and able to be hospitalized for 3 days for the pharmacokinetic assessment (if applicable)
• Willing and able to be hospitalized - if required - in case of interventions (e.g., surgical procedures, major bleeds)
• Written informed consent by the patient, his/her parents or by the patient's legal/authorized representative as applicable

Exclusion Criteria:

• Known congenital dysfibrinogenemia (not applicable for adult patients with hypodysfibrinogenemia in study part II)
• Known bleeding disorder other than congenital fibrinogen deficiency
• History of esophageal variceal bleeding
• Known presence or history of venous/arterial thrombosis or thromboembolic event in the preceding 6 months
• Known presence or history of fibrinogen inhibitory antibodies
• Known presence or history of hypersensitivity to human fibrinogen or human plasma proteins e.g., immunoglobulins, vaccines or hypersensitivity to any of the excipients
• Known positive serology for HIV-1 and HIV-2
• Clinically relevant biochemical or hematological findings (except due to underlying disease or emergency bleeding) outside the normal range (at the investigator's discretion)
• Clinically relevant pathological findings in physical examination including electrocardiogram
• Treatment with any fibrinogen concentrate and/or fibrinogen-containing product within 2 weeks prior to infusion of BT524
• Concomitant medication interacting relevantly with the coagulation system such as: low molecular weight heparin or unfractioned heparin, factor Xa inhibitors, thrombin inhibitors (factor II a inhibitors), antiplatelet drugs (PY12 inhibitors) within 2 weeks prior to infusion of BT524
• Recent vaccination (within 3 weeks prior to infusion)
• Body weight (BW) below 22 kg for patients ≥ 6 years; BW below the 5th percentile of the normal range for children < 6 years (refers to local standards)
• End stage disease
• Abuse of drugs
• Unable to understand and follow the study requirements
• Participation in another interventional clinical study within 30 days before entering the study or during the study
• Pregnant/ nursing woman, or woman of childbearing potential not using reliable/ effective contraceptive method(s) during the study and at least one month after the last administration of study drug (e.g., oral/ injectable/ implantable/ insertable/ topical hormonal contraceptives, intrauterine devices, female sterilization, partner's vasectomy or condoms)
• Any other condition that, to the investigator's judgment, could have an impact on patient's safety or the study results
• Elective surgery during the 14 day PK blood sampling period
• Acute infection
• Clinically relevant increase or decrease in body temperature
• Actively bleeding or anticipated bleeding (including female menorrhea) at the time point of or within 7 days prior to infusion of BT524
• Surgery within 7 days prior to infusion of BT524
• Immobilization within 7 days prior to infusion of BT524
• Intake of alcohol or significantly increased intake of caffeine containing products within 24 hours prior to infusion of BT524
• Blood donation or comparable blood loss within 60 days prior to infusion of BT524
• Excessive physical exercise (extreme sports activities, sauna) within 72 hours prior to infusion of BT524

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: BT524; Part I: A single intravenous infusion of BT524 for assessment of PK/PD of BT524. Part II: A single or repetitive intravenous infusion(s) of BT524 for on-demand prophylaxis/on-demand treatment of bleeding events.

Drug: BT524 (Part I); Single intravenous infusion of 70 mg BT524 per kg body weight.; Other Names: Human Fibrinogen Concentrate; Drug: BT524 (Part II); Single or repetitive intravenous infusion(s) of BT524, depending on the severity of the disorder, location and extent of the bleeding and patient's clinical condition. Dosage based on individual body weight and fibrinogen level.; Other Names: Human Fibrinogen Concentrate

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Single-dose Pharmacokinetics (PK) of BT524: Terminal Elimination Half-life (t1/2) for Fibrinogen Antigen	T1/2 of fibrinogen antigen was determined from samples taken at several time points during the 14 day sampling period. T1/2 was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-dose Pharmacokinetics (PK) of BT524: Time to Maximum Concentration (Tmax) for Fibrinogen Antigen	Time of occurence of Cmax relative to dosing (Tmax) for fibrinogen antigen was determined from samples taken at several time points during the 14 day sampling period. Tmax was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacokinetics (PK) for BT524: Maximum Concentration (Cmax) for Fibrinogen Antigen	Maximum observed plasma concentration (Cmax) for fibrinogen antigen was determined from samples taken at several time points during the 14 day sampling period. Cmax was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacokinetics (PK) for BT524: Area Under the Curve (AUC) Calculated to the Last Measured Concentration (AUC0-tz) for Fibrinogen Antigen	AUC0-tz: Area under the time course of the plasma concentrations calculated from time zero up to the last quantifiable plasma concentration for fibrinogen antigen, was determined from samples taken at several time points during the 14 day sampling period. AUC0-tz was derived from time-concentration profiles using adapted methodology (noncompartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacokinetics (PK) for BT524: Extent of Area Under the Curve (AUC) Extrapolation Beyond Last Concentration (AUCextr) for Fibrinogen Antigen	AUCextr: extent of AUC extrapolation beyond last concentration for fibrinogen antigen, was determined from samples taken at several time points during the 14 day sampling period. AUCextr was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacokinetics (PK) for BT524: Area Under the Curve (AUC) From Time 0 to Infinity (AUC0-∞) for Fibrinogen Antigen	AUC0-∞: AUC from time 0 to infinity for fibrinogen antigen, was determined from samples taken at several time points during the 14 day sampling period. AUC0-∞ was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacokinetics (PK) for BT524: Mean Residence Time (MRT) Extrapolated to Infinity (MRT0-∞) for Fibrinogen Antigen	MRT0-∞: Mean Residence Time (MRT) extrapolated to infinity for fibrinogen antigen was determined from samples taken at several time points during the 14 day sampling period. MRT0-∞ was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacokinetics (PK) for BT524: Clearance (CL) for Fibrinogen Antigen	CL: Total clearance (CL) for fibrinogen antigen was determined from samples taken at several time points during the 14 day sampling period. CL was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacokinetics (PK) for BT524: Volume of Distribution at Presumed Steady-state (Vdss) for Fibrinogen Antigen	Vdss: Volume of distribution at presumed steady-state for fibrinogen antigen was determined from samples taken at several time points during the 14 day sampling period. Vdss was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacokinetics (PK) for BT524: Incremental Recovery (IR) for Fibrinogen Antigen	IR is the dose-adjusted maximum fibrinogen increase in plasma within 4 hours after the end of infusion.	Between pre-dose and 4 hours post-dose
Single-Dose Pharmacokinetics (PK) for BT524: Classical in Vivo Recovery (CIR) for Fibrinogen Antigen	CIR: maximum fibrinogen increase in plasma within 4 hours after the end of infusion divided by the maximum theoretical fibrinogen increase	Between pre-dose and 4 hours post-dose
Single-Dose Pharmacokinetics (PK) for BT524: Volume of Distribution at Presumed Steady-state (Vdss) Per kg Body Weight (BW) for Fibrinogen Antigen	Vdss per kg BW: Volume of distribution at presumed steady-state per kg bodyweight for fibrinogen antigen was determined from samples taken at several time points during the 14 day sampling period. Vdss per kg BW was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Single-dose Pharmacodynamics (PD) of BT524: Terminal Elimination Half-life (t1/2) for Fibrinogen Activity	T1/2 of fibrinogen activity was determined from samples taken at several time points during the 14 day sampling period. T1/2 was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-dose Pharmacodynamics (PD) of BT524: Time to Maximum Concentration (Tmax) for Fibrinogen Activity	Time of occurence of Cmax relative to dosing (Tmax) for fibrinogen activity was determined from samples taken at several time points during the 14 day sampling period. Tmax was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-dose Pharmacodynamics (PD) of BT524: Maximum Concentration (Cmax) for Fibrinogen Activity	Maximum observed plasma concentration (Cmax) for fibrinogen activity was determined from samples taken at several time points during the 14 day sampling period. Cmax was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-dose Pharmacodynamics (PD) of BT524: Area Under the Curve (AUC) Calculated to the Last Measured Concentration (AUC0-tz) for Fibrinogen Activity	AUC0-tz: Area under the time course of the plasma concentrations calculated from time zero up to the last quantifiable plasma concentration for fibrinogen activity, was determined from samples taken at several time points during the 14 day sampling period. AUC0-tz was derived from time-concentration profiles using adapted methodology (noncompartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-dose Pharmacodynamics (PD) of BT524: Extent of Area Under the Curve (AUC) Extrapolation Beyond Last Concentration (AUCextr) for Fibrinogen Activity	AUCextr: extent of AUC extrapolation beyond last concentration for fibrinogen activity, was determined from samples taken at several time points during the 14 day sampling period. AUCextr was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-dose Pharmacodynamics (PD) of BT524: Area Under the Curve (AUC) From Time 0 to Infinity (AUC0-∞) for Fibrinogen Activity	AUC0-∞: AUC from time 0 to infinity for fibrinogen activity, was determined from samples taken at several time points during the 14 day sampling period. AUC0-∞ was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-dose Pharmacodynamics (PD) of BT524: Mean Residence Time (MRT) Extrapolated to Infinity (MRT0-∞) for Fibrinogen Activity	MRT0-∞: Mean Residence Time (MRT) extrapolated to infinity for fibrinogen activity was determined from samples taken at several time points during the 14 day sampling period. MRT0-∞ was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacodynamics (PD) for BT524: Clearance (CL) for Fibrinogen Activity	CL: Total clearance (CL) for fibrinogen activity was determined from samples taken at several time points during the 14 day sampling period. CL was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacodynamics (PD) for BT524: Volume of Distribution at Presumed Steady-state (Vdss) for Fibrinogen Activity	Vdss: Volume of distribution at presumed steady-state for fibrinogen activity was determined from samples taken at several time points during the 14 day sampling period. Vdss was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Single-Dose Pharmacodynamics (PD) for BT524: Incremental Recovery (IR) for Fibrinogen Activity	IR is the dose-adjusted maximum fibrinogen increase in plasma within 4 hours after the end of infusion.	Between pre-dose and 4 hours post-dose
Single-Dose Pharmacodynamics (PD) for BT524: Classical in Vivo Recovery (CIR) for Fibrinogen Activity	CIR: maximum fibrinogen increase in plasma within 4 hours after the end of infusion divided by the maximum theoretical fibrinogen increase	Between pre-dose and 4 hours post-dose
Single-Dose Pharmacodynamics (PD) for BT524: Volume of Distribution at Presumed Steady-state (Vdss) Per kg Body Weight (BW) for Fibrinogen Activity	Vdss per kg BW: Volume of distribution at presumed steady-state per kg bodyweight for fibrinogen activity was determined from samples taken at several time points during the 14 day sampling period. Vdss per kg BW was derived from time-concentration profiles using adapted methodology (non-compartmental analysis, compartment analysis, or population modeling, as appropriate/ required).	Pre-dose on Dosing Day 0, at the end of the infusion and 0.5, 1, 2, 4, 8, 24, 48, 96, 168, 240 and 336 hours post-dose
Change in Maximum Clot Firmness at 1 Hour Post-end of Infusion	Maximum Clot Firmness (MCF), assessed by rotational thromboelastometry (ROTEM), was used as a surrogate marker of haemostatic efficacy following administration of BT524. In Part I, MCF was measured before and 1 hour after the end of a single BT524 infusion. In Part II, MCF was measured before and 1 hour after the end of each BT524 infusion administered to treat bleeding events. The variable was the change in MCF from pre-dose to 1 hour post-end of infusion.	Part I: pre-dose and at 1 hour post-end of infusion. Part II: pre-dose and at 1 hour post-end of infusion of each bleeding event.
Clinical Efficacy for BT524: Overall Hemostatic Response to Treatment With BT524 in Study Part II	Overall hemostatic response (OHR) to treatment with BT524 for each surgical procedure and each treated bleed was rated on a 4-point scale ("none", "moderate", "good" or "excellent"). The sum of good and excellent ratings was defined as "success" in the analysis. Frequencies and percentages of OHR on event level (Success rate in % = number of successfully treated bleeding events / total number of bleeding events).	Part II: Up to 24 hours after end of infusion, or on day of hospital discharge (if between 24 hours and 49 days post-infusion); at the latest on day 49 after the treated bleeding event.
Clinical Efficacy for BT524: Total Loss of Blood for Surgical Bleeding Events in Study Part II	Total loss of blood was rated by the investigator per surgical bleeding events (eg, intra- and post-operatively, rebleedings) using the classifications of "lower than expected", "within the expected range", and "higher than expected". The ratings were analyzed descriptively (frequencies and percentages) on event level for the Full Bleeding Event Set (FBE).	Part II: Up to 24 hours after end of infusion, or on day of hospital discharge (if between 24 hours and 49 days post-infusion); at the latest on day 49 after the treated bleeding event.
Clinical Efficacy for BT524: Units of Other Fibrinogen-containing Products (FCP) Infused Besides BT524 in Study Part II	Units of other fibrinogen-containing products (FCP) infused besides BT524 eg, fresh frozen plasma (FFP) or cryoprecipitate or alternative commercially available fibrinogen concentrates given to counteract hemodynamic instability were documented and analyzed descriptively on event level for the FBE.	Part II: Up to 24 hours after end of infusion, or on day of hospital discharge (if between 24 hours and 49 days post-infusion); at the latest on day 49 after the treated bleeding event.

Collaborators and Investigators

• Sponsor: Biotest
• Collaborators: Accovion GmbH; ICON plc; Phoenix Clinical Research
• Investigators: Principal Investigator: Claudia Djambas Khayat, MD, Hôtel Dieu de France, Dept. of Pediatrics

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2013
• Primary Completion (Actual): May 18, 2020
• Study Completion (Actual): November 18, 2020

Study Registration Dates

• First Submitted: February 3, 2014
• First Submitted That Met QC Criteria: February 17, 2014
• First Posted (Estimated): February 19, 2014

Study Record Updates

• Last Update Posted (Actual): July 3, 2025
• Last Update Submitted That Met QC Criteria: June 17, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: fibrinogen, bleeding,
• Additional Relevant MeSH Terms: Genetic Diseases, Inborn; Hematologic Diseases; Blood Coagulation Disorders; Hemorrhagic Disorders; Blood Coagulation Disorders, Inherited; Coagulation Protein Disorders; Afibrinogenemia
• Other Study ID Numbers: Biotest 984; 2011-004154-25 (EudraCT Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No