EVALUATION OF THE OVERALL HAEMOSTATIC CAPACITY OF MIM8 WITH GLOBAL HAEMOSTASIS ASSAYS AND FIBRIN CLOT ULTRASTRUCTURE

Hemophilia A Clinical Trial

— Mim8-TGT  

Official title:

EVALUATION OF THE OVERALL HAEMOSTATIC CAPACITY OF MIM8 WITH GLOBAL HAEMOSTASIS ASSAYS AND FIBRIN CLOT ULTRASTRUCTURE

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT06212505
• Other study ID #: 69HCL23_1202
• Status: Recruiting
• Start date: March 28, 2024
• Est. completion date: May 28, 2025

Study information

• Verified date: April 2024
• Source: Hospices Civils de Lyon
• Contact: Gamze DARGAUD, Pr
• Phone: 04 72 11 88 10
• Email: gamze.dargaud[@]chu-lyon.fr
• Is FDA regulated: No
• Study type: Observational

Clinical Trial Summary

Hemophilia A is an X linked disorder characterized by a deficiency in Factor VIII. The clinical hallmark of this disease is increased tendency to spontaneous bleeding with hemarthrosis accounting for 90% of the hemorrhages. In addition to development of hemophilic arthropathy, the emergence of alloantibodies that inhibit the coagulant activity of FVIII remains the most feared complication related to the treatment of hemophilia A. 30% of patients with hemophilia A develop these inhibitors, making treatment with standard replacement therapy ineffective. Up until the approval of emicizumab, bypassing agents like activated prothrombin complex concentrate (aPCC) and activated recombinant activated factor VII (rFVIIa) were the only approved therapies for the treatment hemophilia A with inhibitors. The response to bypassing therapy is often unpredictable, variable and difficult to monitor.

Emicizumab is a first generation bispecific antibody mimicking the activity of FVIIIa in tenase complex. Early in the HAVEN 1 clinical trial with emicizumab (1), cases of thrombotic microangiopathy (TMA) and thrombotic events were reported when on average a cumulative amount of >100 U/kg/24 hours of aPCC was administered for 24 hours or more to patients receiving emicizumab, resulting in a protocol adjustment for the HAVEN 1 trial and subsequent trials to recommend using the lowest doses of bypassing agents expected to achieve hemostasis, and avoiding the combination of emicizumab and aPCC if possible. So far the only proposed strategies for treating events of breakthrough bleeds in patients on emicizumab prophylaxis include rFVIIa, FVIII in patients with a low titer of inhibitors, and lower doses of aPCC, knowing that emicizumab provides an existing level of thrombin generation. (2) While the exact mechanism leading to the development of thrombotic complications (TMA and VTE) remains poorly understood, many speculated on the accumulation of FIX and FX, the substrates of emicizumab, with multiple doses of aPCC (3)

Mim8 is a novel, next-generation FVIIIa mimetic designed for the subcutaneous prophylactic treatment of patients with HA with and without inhibitors. Mim8 is a fully human, bispecific antibody that mimics FVIIIa function by bridging FIXa and FX on the phospholipid surface of activated platelets, enhancing the proteolytic activity of FIXa, and thus facilitating effective FX activation. Data from studies using in vitro HA-like human blood, as well as in vivo HA mouse models, indicate that Mim8 is ~15-fold more potent than a sequence identical analogue (SIA) of the FVIII mimetic emicizumab (4). Mim8 nonclinical safety program in cynomolgus monkeys showed that subcutaneous administration of up to 3 mg/kg/week (several fold greater than expected clinical exposure) for 26 weeks resulted in relevant pharmacodynamic effects, observed in thrombin generation and APTT, with no signs of thrombi or excessive coagulation activation. So far, Mim8 procoagulant activity was evaluated in platelet poor plasma samples only (5,6)

This in vitro study aims to evaluate TGA to monitor Mim8. We hypothesized that TG profiles (ETP and peak thrombin) may be different with different triggers used. We recently modified TGA to better detect haemostatic activity of emicizumab, by using a combined trigger (low TF+low FIXa). Differently from emicizumab, Mim8 stimulates the proteolytic activity of FIXa in the range of 15,000-fold. TGA test conditions may be therefore different for Mim8 and emicizumab.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 6
• Est. completion date: May 28, 2025
• Est. primary completion date: May 28, 2025
• Accepts healthy volunteers: No
• Gender: Male
• Age group: 18 Years to 99 Years

Eligibility

Inclusion Criteria:

• Male patients,

• Age > 18 years at time of inclusion

• Diagnosis of severe hemophilia A (FVIII <2%)

• Severe hemophilia A (FVIII <2%) and not receiving emicizumab prophylaxis

• Obtaining the patient's non-opposition

• Ability to comply with the study protocol, in the investigator's judgment

Exclusion Criteria:

• Not willing to provide extra blood for the experiments

• Patients carrying the diagnoses of other coagulopathies in addition to hemophilia A

• Patients that have received any hemostatic agent within 5 half-lives of the blood draw.

Related Conditions & MeSH terms

• Hemophilia A

Intervention

Other:
• blood test
blood test at the inclusion 10 tubes of 2.7mL blood

Locations

Country	Name	City	State
France	Centre de Référence Hémophilie, Hôpital Louis Pradel- Hospices Civils de Lyon	Bron	Rhone

Sponsors (1)

Lead Sponsor	Collaborator
Hospices Civils de Lyon

Country where clinical trial is conducted

France, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Determination of thrombin generation (TG) (ETP and peak thrombin) will be obtained in platelet-poor plasma from patients with severe HA	27 ml blood samples will be taken from each patient, and FVIII activity will be measured in the samples. Mim8 and emicizumab will be added to the blood samples, and thrombin generation will be performed using different triggers.; All statistical analyses were performed using GraphPad Prism and GraphPad Instat softwares (GraphPad Software, La Jolla, CA, USA). The probability of statistical difference between experimental groups will be determined by unpaired Mann-Whitney and ANOVA tests. Results will be expressed as mean ± standard deviation (SD). A p-value < 0.05 will be considered statistically significant	One point at the inclusion