Enoxaparin, Tinzaparin, and Apixaban Modulate Cancer Cell Procoagulant Activity and Viability: Comparison with Quercetin.

Background/Objectives: Tissue factor (TF)-expressing cancer cells and their extracellular vesicles (CaCe-dEVs) are key drivers of cancer-associated hypercoagulability and vascular dysfunction. While low-molecular-weight heparins (LMWHs) and direct FXa inhibitors are standard therapies for cancer-associated thrombosis, their direct effects on cancer cell procoagulant potential and endothelial responses remain incompletely defined. This study compared the impact of LMWHs (enoxaparin, tinzaparin), apixaban, and quercetin on cancer cell viability, thrombin generation, and CaCe-dEVs-induced endothelial injury. Methods: Pancreatic (BXPC3) and breast (MCF7) cancer cells and their vesicles were analyzed for TF expression and thrombin generation. Human umbilical vein endothelial cells (HUVECs) were pretreated with each agent prior to vesicle exposure. Cell viability, thrombin generation, and endothelial morphology were assessed using standard assays and microscopy. Results: Tinzaparin and quercetin significantly reduced cancer cell viability, whereas enoxaparin and apixaban showed no cytotoxicity. None of the agents affected HUVEC viability. All suppressed TF-mediated thrombin generation induced by cancer cells, with tinzaparin being most effective in BXPC3 cells. Quercetin exhibited a partial and limited protective effect on endothelial cells against CaCe-dEVs-induced dysfunction, while LMWHs and apixaban did not prevent endothelial damage. Conclusions: These findings suggest that LMWHs, apixaban, and quercetin modulate cancer-cell-driven hypercoagulability beyond anticoagulation, with quercetin and tinzaparin showing additional cytotoxic potential. Such dual effects may reduce thrombosis risk while impacting tumor progression, meriting further investigation.