Clinical trial • Phase III • Cardiology | Haematology

HUMAN IGG4 S228P MONOCLONAL ANTIBODY AGAINST FACTOR XI AND ACTIVATED FACTOR XI for Venous thromboembolism (VTE) | Thromboembolic disease

Phase III trial of HUMAN IGG4 S228P MONOCLONAL ANTIBODY AGAINST FACTOR XI AND ACTIVATED FACTOR XI for Venous thromboembolism (VTE) | Thromboembolic diseas…

Overview

Trial Therapeutic Area
Cardiology | Haematology
Trial Disease
Venous thromboembolism (VTE) | Thromboembolic disease
Trial Stage
Phase III
Drug Modality
Monoclonal antibody | Small molecule

Key dates

Initial CTIS Submission Date
13-06-2025
First CTIS Authorization Date
08-10-2025

Trial design

Randomised, open-label, apixaban (eliquis) 2.5 mg film-coated tablets, oral; enoxaparin (clexane) 4 000 ui (40 mg)/0.4 ml solution for injection, subcutaneous; sodium chloride (placebo) iv/infusion (listed as placebo).-controlled Phase III trial in Bulgaria, Lithuania, Poland and others.

Randomised
Yes
Open Label
Yes
Comparator
Apixaban (Eliquis) 2.5 mg film-coated tablets, oral; Enoxaparin (CLEXANE) 4 000 UI (40 mg)/0.4 ml solution for injection, subcutaneous; Sodium chloride (placebo) IV/infusion (listed as placebo).
Target Sample Size
933

Eligibility

Recruits 933 No vulnerable populations selected; participants are adults. No specific consent/assent handling for vulnerable populations is indicated in the CTIS record..

Vulnerable Population
No vulnerable populations selected; participants are adults. No specific consent/assent handling for vulnerable populations is indicated in the CTIS record.

Inclusion criteria

  • {"criterion_text":"- Is undergoing a primary elective unilateral TKA ."}
  • {"criterion_text":"- Is in good health based on laboratory safety testing as described in the protocol."}
  • {"criterion_text":"- Body weight <130 kg at screening visit as described in the protocol."}
  • {"criterion_text":"- Other protocol-defined Inclusion Criteria apply."}

Exclusion criteria

  • {"criterion_text":"- Any condition that, as assessed by the investigator, may confound the results of the study or pose an additional risk to the participant by study participation."}
  • {"criterion_text":"- History of bleeding in the 6 months prior to randomization requiring hospitalization or transfusion as described in the protocol."}
  • {"criterion_text":"- History of thromboembolic disease or thrombophilia."}
  • {"criterion_text":"- History of major surgery, including brain, spinal, or ocular, or major trauma within approximately the past 6 months prior to randomization."}
  • {"criterion_text":"- Has an estimated Glomerular Filtration Rate (GFR) of <30 mL/min/1.73 m2 at the screening visit as described in the protocol."}
  • {"criterion_text":"- Other protocol-defined Exclusion Criteria apply."}

Endpoints

Primary endpoints

  • {"endpoint_text":"- Incidence of the composite endpoint of asymptomatic or symptomatic Venous Thromboembolism (VTE) [including VTE-related death].","definition_or_measurement_approach":""}

Secondary endpoints

  • {"endpoint_text":"- Incidence of confirmed symptomatic Deep Venous Thrombosis (DVT).","definition_or_measurement_approach":""}
  • {"endpoint_text":"- Incidence of confirmed Pulmonary Embolism (PE).","definition_or_measurement_approach":""}
  • {"endpoint_text":"- Incidence of VTE-related death.","definition_or_measurement_approach":""}
  • {"endpoint_text":"- Incidence of the composite endpoint of major and clinically relevant nonmajor (CRNM) bleeding.","definition_or_measurement_approach":""}
  • {"endpoint_text":"- Incidence of the composite endpoint of asymptomatic or symptomatic VTE (including VTE-related death).","definition_or_measurement_approach":""}
  • {"endpoint_text":"- Incidence of minor bleeding.","definition_or_measurement_approach":""}
  • {"endpoint_text":"- Incidence of Treatment Emergent Adverse Events (TEAEs).","definition_or_measurement_approach":""}
  • {"endpoint_text":"- Incidence of Anti-Drug Antibodies (ADA) to REGN7508.","definition_or_measurement_approach":""}
  • {"endpoint_text":"- Titer of ADA to REGN7508.","definition_or_measurement_approach":""}
  • {"endpoint_text":"- Concentrations of REGN7508.","definition_or_measurement_approach":""}

Recruitment

Planned Sample Size
933
Recruitment Window Months
23
Consent Approach
Informed consent obtained from adult participants. Subject information and ICF documents available in multiple languages as listed (English, Polish, Lithuanian, Latvian, Russian, Bulgarian, Hungarian, Romanian). No assent procedures or additional vulnerable-population consent processes are indicated in the CTIS entries.

Methods

  • Site-based recruitment at participating orthopedic hospitals/clinics (use of recruitment posters and site materials as listed in K2 recruitment posters and K1 recruitment procedure descriptions).
  • Patient recruitment services provided by Clariness GmbH (listed with role 'Patient Recruitment'; contact claudia.luciano@clariness.com).
  • Country-specific recruitment procedure documents and venography guidance materials (country K1/K2 documents listed for Poland, Lithuania, Latvia, Hungary, Bulgaria, Romania).

Geography

Total Number Of Sites
23
Total Number Of Participants
1087

Bulgaria

Earliest CTIS Part Ii Submission Date
01-09-2025
Latest Decision Or Authorization Date
08-01-2026
Processing Time Days
130
Number Of Sites
3
Number Of Participants
60

Sites

Site Name
Multi-profile Hospital for Active Treatment Heart and Brain EAD
Department Name
100022: Orthopedics and Traumatology Clinic
Contact Person Name
Georgi Dimitrov
Contact Person Email
g.dimitrov@doctor.com
Site Name
Umbal - Prof. D-R Stoyan Kirkovich AD
Department Name
100001: Orthopedics and Traumatology Clinic
Contact Person Name
Nedko Dimitrov
Contact Person Email
dr.dimitrovn@gmail.com
Site Name
Multispecialty hospital for active treatment Sveta Sofia EOOD
Department Name
100002: Clinic of Orthopaedics and Traumatology
Contact Person Name
Hristo Mazneykov

Lithuania

Earliest CTIS Part Ii Submission Date
05-09-2025
Latest Decision Or Authorization Date
17-02-2026
Processing Time Days
166
Number Of Sites
3
Number Of Participants
330

Sites

Site Name
Lietuvos sveikatos mokslu universiteto Kauno ligonine
Department Name
440033: Joint replacement & sports tra
Contact Person Name
Juozas Belickas
Contact Person Email
juozasbelickas@gmail.com
Site Name
Lietuvos sveikatos mokslu universiteto ligonine Kauno klinikos
Department Name
440022: Kauno klinikos
Contact Person Name
Alfredas Smailys
Site Name
Klaipedos universiteto ligonine VšĮ
Department Name
440011: orthopaedic
Contact Person Name
Algimantas Cebatorius
Contact Person Email
a.cebatorius@gmail.com

Poland

Earliest CTIS Part Ii Submission Date
09-09-2025
Latest Decision Or Authorization Date
23-01-2026
Processing Time Days
137
Number Of Sites
5
Number Of Participants
100

Sites

Site Name
Samodzielny Publiczny Zaklad Opieki Zdrowotnej Centralny Szpital Kliniczny Uniwersytetu Medycznego W Lodzi
Department Name
616022: Klinika Ortopedii z Pododdzialem Ortopedii Dzieciecej
Contact Person Name
Andrzej Borowski
Contact Person Email
andrzej.borowski@umed.lodz.pl
Site Name
Szpital Specjalistyczny Im. Ludwika Rydygiera W Krakowie Sp. z o.o.
Department Name
616001: Oddział Ortopedii i Traumatologii Narzadu Ruchu
Contact Person Name
Grzegorz Kwiatkowski
Contact Person Email
kwiatkowskigrzegorz@gmail.com
Site Name
Uniwersytecki Szpital Kliniczny Nr 2 Uniwersytetu Medycznego W Lodzi SPZOZ
Department Name
616002: Klinika Ortopedii
Contact Person Name
Marcin Domzalski
Contact Person Email
marcin.domzalski@umed.lodz.pl
Site Name
Samodzileny Publiczny Zaklad Opieki Zdrowotnej W Radzyniu Podlaskim
Department Name
616003: Oddzial Urazowo-Ortopedyczny
Contact Person Name
Robert Weglowski
Contact Person Email
r.weglowski@wp.pl
Site Name
Ortopedyczno-Rehabilitacyjny Szpital Kliniczny Im Wiktora Degi Uniwersytetu Medycznego Im Karola Marcinkowskiego W Poznaniu
Department Name
616004:Klinika Ortopedii i Traumatologii - Oddział Urazowo - Ortopedyczny, Alloplastyki Stawów Bio
Contact Person Name
Tomasz Trzeciak
Contact Person Email
ortopedia@orsk.pl

Hungary

Earliest CTIS Part Ii Submission Date
05-08-2025
Latest Decision Or Authorization Date
15-01-2026
Processing Time Days
164
Number Of Sites
5
Number Of Participants
130

Sites

Site Name
University Of Szeged
Department Name
348004: Traumatologiai es Ortopediai Klinika
Contact Person Name
Gellert Sohar
Contact Person Email
gsohar@gmail.com
Site Name
Jasz-Nagykun-Szolnok Varmegyei Hetenyi Geza Korhaz-Rendelointezet
Department Name
348005: Mozgasszervi Centrum Ortopediai Osztalya
Contact Person Name
Gergo Tajti
Contact Person Email
tajtiger78@gmail.com
Site Name
Semmelweis University
Department Name
348001:Ortopédiai Klinika
Contact Person Name
György Szőke
Site Name
Gyor-Moson-Sopron Varmegyei Petz Aladar Egyetemi Oktato Korhaz
Department Name
348002-Traumatológiai, ortopédiai és kézsebészeti szakmacsoport
Contact Person Name
Gunther Tibor
Contact Person Email
gunther.tibor@gmail.com
Site Name
University Of Debrecen
Department Name
348003: Ortopediai és Traumatologiai Klinika
Contact Person Name
Zoltan Karacsonyi

Latvia

Earliest CTIS Part Ii Submission Date
05-09-2025
Latest Decision Or Authorization Date
20-01-2026
Processing Time Days
138
Number Of Sites
5
Number Of Participants
447

Sites

Site Name
Orto klinika SIA
Department Name
428044: NAP
Contact Person Name
Andrejs Peredistijs
Contact Person Email
andrejs@orto.lv
Site Name
Vidzemes Slimnica SIA
Department Name
428022: Trauma
Contact Person Name
Aivars Baurovskis
Contact Person Email
ai.bau@inbox.lv
Site Name
Liepajas Regionala Slimnica SIA
Department Name
428055: Urology
Contact Person Name
Uldis Argalis
Contact Person Email
uldisargalis@inbox.lv
Site Name
Riga 2nd Hospital
Department Name
428033: orthopedics and trauma
Contact Person Name
Sandris Petronis
Contact Person Email
sandris.petronis@gmail.com
Site Name
Traumatologijas Un Ortopedijas Slimnica SIA
Department Name
428011: NAP
Contact Person Name
Maris Zambrans
Contact Person Email
maris.zambrans@tos.lv

Romania

Earliest CTIS Part Ii Submission Date
12-01-2026
Latest Decision Or Authorization Date
23-02-2026
Processing Time Days
43
Number Of Sites
2
Number Of Participants
20

Sites

Site Name
Arensia Clinics S.R.L.
Department Name
642002: Orthopaedics & Traumatology
Contact Person Name
Răzvan Ene
Contact Person Email
razvan.ene.ext@arensia-em.com
Site Name
Spitalul Clinic Judetean De Urgenta Cluj
Department Name
642001: Internal Medicine
Contact Person Name
Mihaela Mocan

Sponsor

Primary sponsor

Full Name
Regeneron Pharmaceuticals Inc.
Organisation Type
Pharmaceutical company
Country Of Registered Address
United States

Contract research organisations

Name
Parexel International (IRL) Limited
Responsibilities
CRO

Third parties

  • {"country":"Netherlands","full_name":"Itreas B.V.","duties_or_roles":"Imaging","organisation_type":"Pharmaceutical company"}
  • {"country":"United States","full_name":"Perceptive Informatics Inc.","duties_or_roles":"","organisation_type":"Pharmaceutical company"}
  • {"country":"Germany","full_name":"Clariness GmbH","duties_or_roles":"Patient Recruitment","organisation_type":"Non-Pharmaceutical company"}
  • {"country":"Ireland","full_name":"Parexel International (IRL) Limited","duties_or_roles":"CRO","organisation_type":"Pharmaceutical company"}
  • {"country":"Slovakia","full_name":"SanaClis s.r.o.","duties_or_roles":"Investigational Product/Clinical Supplies","organisation_type":"Pharmaceutical company"}
  • {"country":"United States","full_name":"Pharmaceutical Product Development LLC","duties_or_roles":"Central Lab","organisation_type":"Pharmaceutical company"}

Investigational products

Investigational Product Name
REGN7508 (POWDER FOR SOLUTION FOR INFUSION)
Active Substance
HUMAN IGG4 S228P MONOCLONAL ANTIBODY AGAINST FACTOR XI AND ACTIVATED FACTOR XI
Modality
Monoclonal antibody
Routes Of Administration
INTRAVENOUS INJECTION
Route
INTRAVENOUS INJECTION
Authorisation Status
prodAuthStatus 1 (investigational as recorded)
Investigational Product Name
REGN7508 (SOLUTION FOR INJECTION)
Active Substance
REGN7508
Modality
Monoclonal antibody
Routes Of Administration
SUBCUTANEOUS INJECTION
Route
SUBCUTANEOUS INJECTION
Authorisation Status
prodAuthStatus 1 (investigational as recorded)

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