NHP Arteriovenous Shunt Thrombosis Model in Cynomolgus Monkeys For Translational Antithrombotic Drug Evaluation

Thrombotic disorders remain one of the leading causes of morbidity and mortality worldwide, driving continuous innovation in anticoagulant and antithrombotic drug development. While traditional anticoagulants such as heparins and direct oral anticoagulants (DOACs) have significantly improved clinical management, bleeding liability remains a major limitation that constrains therapeutic windows and long-term safety.

In recent years, emerging targets within the intrinsic coagulation pathway - particularly coagulation Factor XI (FXI) and FXIa - have attracted substantial attention as potential next-generation antithrombotic strategies. These approaches aim to achieve effective thrombosis inhibition while minimizing bleeding risk, an objective often referred to as "uncoupling thrombosis from hemostasis."

However, translational evaluation of novel anticoagulants remains challenging. Rodent thrombosis models frequently fail to fully recapitulate human coagulation physiology, platelet biology, vascular responses, and pharmacodynamic characteristics. Consequently, non-human primate (NHP) thrombosis models are increasingly recognized as critical translational platforms for assessing antithrombotic efficacy, coagulation biomarkers, and bleeding liability prior to clinical development.

Leveraging its specialized hematology and cardiovascular pharmacology platform, Prisys Biotechnologies has established a highly standardized cynomolgus monkey femoral arteriovenous (AV) shunt thrombosis model designed for translational evaluation of anticoagulants, biologics, and novel coagulation pathway modulators. The platform integrates surgical expertise, quantitative thrombus assessment, coagulation biomarker analysis, and bleeding risk evaluation within a clinically relevant NHP system.

The coagulation system represents a highly coordinated interaction among vascular endothelium, circulating platelets, coagulation factors, inflammatory mediators, and blood flow dynamics. Small differences in these pathways can substantially affect translational predictability during drug development.

Although rodent thrombosis models provide useful mechanistic insights, several limitations reduce their predictive value for clinical anticoagulant development:

• Significant species differences in coagulation factor expression and activity

• Differences in platelet reactivity and thrombin generation

• Limited comparability of pharmacodynamic biomarkers

• Reduced predictive value for bleeding risk assessment

• Inability to fully reproduce human vascular intervention procedures

These limitations become particularly important for emerging therapeutic classes such as FXI inhibitors, bispecific antibodies, RNA therapeutics, and gene-editing approaches targeting coagulation pathways.

Non-human primates offer substantially improved translational relevance because of their closer homology to humans in coagulation physiology, hematological parameters, vascular anatomy, and drug metabolism. Cynomolgus monkeys are therefore increasingly utilized in advanced thrombosis and hemostasis research programs.

The AV shunt thrombosis model is a well-established translational thrombosis platform designed to quantitatively evaluate thrombus formation under controlled blood flow conditions. At Prisys Biotechnologies, the model has been optimized for reproducibility, surgical consistency, and quantitative endpoint sensitivity in cynomolgus monkeys.

Under deep anesthesia and sterile surgical conditions, the femoral artery and femoral vein are surgically isolated approximately 3 cm below the inguinal region. A specially designed AV shunt catheter system containing a U-shaped thrombogenic wire is then inserted sequentially into the venous and arterial vessels. The thrombogenic wire acts as a controlled surface for thrombus generation during blood circulation through the extracorporeal shunt system.

Following catheter placement, arterial clamps are released to initiate continuous blood circulation through the AV shunt loop. Circulation time is precisely controlled to ensure standardized thrombus formation conditions across experimental groups. Because thrombus generation occurs under dynamic blood flow conditions, the model closely mimics clinically relevant thrombogenic processes involving platelet activation, coagulation cascade initiation, and fibrin formation. Compared with static clotting assays, this dynamic circulation system provides substantially greater translational relevance for evaluating antithrombotic therapies.

At the conclusion of the circulation period, the thrombogenic U-shaped wire and attached thrombus are carefully removed from the catheter system. After gentle saline washing to remove excess fluid, the thrombus-bearing wire is weighed using a high-precision analytical balance. Net thrombus weight is then calculated by subtracting the baseline wire weight from the total measured weight. This quantitative thrombus net weight endpoint provides high assay sensitivity, strong reproducibility, dose-response evaluation capability, and direct pharmacodynamic assessment of antithrombotic efficacy.

• Closer Human Coagulation Biology: Cynomolgus monkeys exhibit coagulation factor profiles and platelet responses highly comparable to humans.
• Clinically Relevant Biomarker Assessment: The model supports integrated coagulation biomarker analysis, including aPTT, PT, and thrombin generation markers.
• Dynamic Hemodynamic Conditions: Unlike simplified in vitro coagulation assays, the AV shunt system reproduces thrombus formation under continuous blood flow.

• Longitudinal Pharmacodynamic Evaluation: The model is non-terminal and minimally invasive, allowing repeated measurements.

Prisys Biotechnologies supports a broad range of bleeding and clotting disease research. Their integrated services include PK/PD evaluation services and advanced clinical imaging platform integration. As the field moves toward precision anticoagulation and target-selective coagulation modulation, advanced NHP thrombosis platforms remain essential for validating next-generation therapeutic strategies before clinical translation.

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