Unmet clinical needs in the prevention and treatment of cancer-associated venous thromboembolism

Cancer-associated splanchnic vein thrombosis: Clinical implications and management considerations

Splanchnic vein thrombosis (SVT), a thrombosis which involves the portal, mesenteric, and splenic veins, and the Budd-Chiari syndrome, represents an uncommon type of venous thromboembolism (VTE). Like with deep vein thrombosis of the lower extremities and pulmonary embolism, ample evidence suggests a significant association between SVT and cancer, particularly intra-abdominal solid malignancies (e.g. hepatobiliary and pancreatic cancers) and myeloproliferative neoplasms (MPN). Clinical symptoms of SVT in cancer patients can be ambiguous, and frequently attributed to the primary cancer itself. Alternatively, SVT may be asymptomatic and detected incidentally during cancer staging or follow-up evaluations. SVT can also precede the diagnosis of cancer and has been associated with poorer outcomes in patients with liver or pancreatic cancers. Therefore, an unprovoked SVT warrants a thorough evaluation for an underlying malignancy or MPN. Cancer-associated SVT carries a high risk of VTE extension, recurrence and bleeding. Extended anticoagulant treatment is often required in the absence of a high bleeding risk. Guidelines suggest treatment with either low molecular weight heparin (LMWH) or direct oral anticoagulants (DOACs), although available data on the safety and effectiveness of DOACs in these patients is limited. This comprehensive review outlines the epidemiology, pathogenesis, risk factors, and diagnosis of cancer-associated SVT and underscores the importance of comprehensive patient evaluation and evidence-based management.

Low-Dose Rivaroxaban to Prevent Recurrences of Venous Thromboembolism in Cancer: A Real-Life Experience with a Focus on Female Patients

BACKGROUND

The way in which to prevent recurrent venous thromboembolism (VTE) is an unmet clinical need in cancer patients. International guidelines only provide conditional recommendations and do not specify which anticoagulant and dose should be used. In the last 2 years, we have been using low-dose rivaroxaban to prevent VTE recurrences in cancer patients. The results of this real-life experience are presented in this study.

METHODS

All patients had cancer and had previously completed a cycle of at least six months of full-dose anticoagulation for the treatment of a VTE index event, before receiving a prescription of low-dose rivaroxaban (10 mg once daily) for secondary prevention of VTE. Effectiveness and safety of this therapeutic regimen were evaluated in terms of VTE recurrences, major bleedings (MB), and clinically relevant non-major bleedings (CRNMB).

RESULTS

The analysis included 106 cancer patients. Their median age was 60 years (IQR 50-69). Metastatic cancer was present in 87 patients (82.1%). Six patients (5.7%) had brain metastases. Over a median follow-up time of 333 days (IQR 156-484), the incidence of VTE recurrences was 3.8% (95%CI 1.0-9.4), with a recurrence rate of 4.0 per 100 person-years (95%CI 1.1-10.2). We observed no MB (0.0%) and three CRNMB (2.8%) (95%CI 0.6-8.1).

CONCLUSIONS

Low-dose rivaroxaban is potentially effective and safe in cancer patients that require prevention of recurrent VTE. Large-scale studies are needed to confirm these findings.

Chymase Inhibition Resolves and Prevents Deep Vein Thrombosis Without Increasing Bleeding Time in the Mouse Model

Background Deep vein thrombosis (DVT) is the primary cause of pulmonary embolism and the third most life-threatening cardiovascular disease in North America. Post-DVT anticoagulants, such as warfarin, heparin, and direct oral anticoagulants, reduce the incidence of subsequent venous thrombi. However, all currently used anticoagulants affect bleeding time at various degrees, and there is therefore a need for improved therapeutic regimens in DVT. It has recently been shown that mast cells play a crucial role in a DVT murine model. The underlying mechanism involved in the prothrombotic properties of mast cells, however, has yet to be identified. Methods and Results C57BL/6 mice and mouse mast cell protease-4 (mMCP-4) genetically depleted mice (mMCP-4 knockout) were used in 2 mouse models of DVT, partial ligation (stenosis) and ferric chloride-endothelial injury model of the inferior vena cava. Thrombus formation and impact of genetically repressed or pharmacologically (specific inhibitor TY-51469) inhibited mMCP-4 were evaluated by morphometric measurements of thrombi immunochemistry (mouse and human DVT), color Doppler ultrasound, bleeding times, and enzymatic activity assays ex vivo. Recombinant chymases, mMCP-4 (mouse) and CMA-1 (human), were used to characterize the interaction with murine and human plasmin, respectively, by mass spectrometry and enzymatic activity assays. Inhibiting mast cell-generated mMCP-4, genetically or pharmacologically, resolves and prevents venous thrombus formation in both DVT models. Inferior vena cava blood flow obstruction was observed in the stenosis model after 6 hours of ligation, in control- but not in TY-51469-treated mice. In addition, chymase inhibition had no impact on bleeding times of healthy or DVT mice. Furthermore, endogenous chymase limits plasmin activity in thrombi ex vivo. Recombinant mouse or human chymase degrades/inactivates purified plasmin in vitro. Finally, mast cell-containing immunoreactive chymase was identified in human DVT. Conclusions This study identified a major role for mMCP-4, a granule-localized protease of chymase type, in DVT formation. These findings support a novel pharmacological strategy to resolve or prevent DVT without affecting the coagulation cascade through the inhibition of chymase activity.

Multidisciplinary Care for the Prevention and Treatment of Venous Thromboembolism in Patients with Cancer-Associated Thrombosis (CAT): Impact of Educational Interventions on CAT-Related Events and on Patients' and Clinicians' Awareness

Cancer is a leading cause of death. Venous thromboembolism (VTE) is an often-overlooked cause of morbidity and mortality in cancer patients that can be readily prevented and treated. Actions are needed to reduce the morbidity and mortality of patients with cancer-associated thrombosis (CAT). There is a need to increase awareness of the impact of CAT on cancer patients' morbidity and mortality, on their quality of life and to understand the importance of more effective preventions and treatments of VTE in cancer patients. Moreover, it is of great importance to systematically assess the risk of VTE in regard to patients, cancer and treatment-related factors. Unfortunately, there are unmet clinical needs in the prevention and treatment of cancer-associated VTE. In this review, we discuss an action plan to ensure an increased awareness of and education on the issues that need to be addressed in order to improve the provision of appropriate prevention, early diagnosis and effective and safe treatment of VTE to all cancer patients and, ultimately, to reduce morbidity and mortality.