Histopathological Features of Cancer-Associated Venous Thromboembolism: Presence of Intrathrombus Cancer Cells and Prothrombotic Factors

Histological differences among thrombi in thrombotic diseases

PURPOSE OF REVIEW

This review aims to summarize the histological differences among thrombi in acute myocardial infarction, ischemic stroke, venous thromboembolism, and amniotic fluid embolism, a newly identified thrombosis.

RECENT FINDINGS

Acute coronary thrombi have a small size, are enriched in platelets and fibrin, and show the presence of fibrin and von Willebrand factor, but not collagen, at plaque rupture sites. Symptomatic deep vein thrombi are large and exhibit various phases of time-dependent histological changes. Cancer-associated venous thromboemboli contain invasive cancer cells that penetrate the vascular walls, and small cancer cell aggregates are observed within the thrombi. The thrombus composition in atherosclerotic and cardioembolic ischemic strokes varies from case to case, while the thrombi in cancer-associated ischemic stroke are rich in platelets and fibrin. A pathological study on amniotic fluid embolism identified uterine vein thrombi and massive platelet-rich microthrombi in the lungs.

SUMMARY

Atherothrombus formation is induced by plaque disruption and may occlude a narrow lumen within a short time. Venous thrombi may grow to a large size in a multistage or chronic manner. Cancer cells can directly contribute to venous thrombus formation. The thrombus formation in amniotic fluid embolism may explain the occurrence of consumptive coagulopathy and cardiopulmonary collapse.

Role of Podoplanin (PDPN) in Advancing the Progression and Metastasis of Glioblastoma Multiforme (GBM)

Glioblastoma multiforme (GBM) is a malignant primary brain tumor categorized as a Grade 4 astrocytic glioma by the World Health Organization (WHO). Some of the established risk factors of GBM include inherited genetic syndromes, body mass index, alcohol consumption, use of non-steroidal anti-inflammatory drugs (NSAIDs), and therapeutic ionizing radiation. Vascular anomalies, including local and peripheral thrombosis, are common features of GBM. Podoplanin (PDPN), a ligand of the C-type lectin receptor (CLEC-2), promotes platelet activation, aggregation, venous thromboembolism (VTE), lymphatic vessel formation, and tumor metastasis in GBM patients. It is regulated by Prox1 and is expressed in developing and adult mammalian brains. It was initially identified on lymphatic endothelial cells (LECs) as the E11 antigen and on fibroblastic reticular cells (FRCs) of lymphoid organs and thymic epithelial cells as gp38. In recent research studies, its expression has been linked with prognosis in GBM. PDPN-expressing cancer cells are highly pernicious, with a mutant aptitude to form stem cells. Such cells, on colocalization to the surrounding tissues, transition from epithelial to mesenchymal cells, contributing to the malignant carcinogenesis of GBM. PDPN can be used as an independent prognostic factor in GBM, and this review provides strong preclinical and clinical evidence supporting these claims.

Didang decoction attenuates cancer-associated thrombosis by inhibiting PAD4-dependent NET formation in lung cancer

This research aims to investigate the impact of Didang decoction (DD) on the formation of neutrophil extracellular traps (NETs) and cancer-associated thrombosis in lung cancer. BALB/c nude mice were used to establish xenograft models for inducing deep vein thrombosis. Tumor growth and thrombus length were assessed. The impact of DD on NET generation was analyzed using enzyme-linked immunosorbent assay, immunofluorescence staining, quantitative real-time PCR, and western blot analysis, both in vivo and in vitro. CI-amidine, a PAD4 inhibitor, was employed to evaluate the role of PAD4 in the generation of NETs. In vivo studies demonstrated that treatment with DD reduced tumor growth, inhibited thrombus formation, and decreased the levels of NET markers in the serum, tumor tissues, neutrophils, and thrombus tissues of mice. Additional data indicated that DD could suppress neutrophil counts, the release of tissue factor (TF), and the activation of thrombin-activated platelets, all of which contributed to increased formation of NETs in mouse models. In vitro, following incubation with conditioned medium (CM) derived from Lewis lung carcinoma cells, the expression of NET markers in neutrophils was significantly elevated, and an extracellular fibrous network structure was observed. Nevertheless, these NET-associated changes were partially counteracted by DD. Additionally, CI-amidine reduced the expression of NET markers in CM-treated neutrophils, consistent with the effects of DD. Collectively, DD inhibits cancer-associated thrombosis in lung cancer by decreasing PAD4-dependent NET formation through the regulation of TF-mediated thrombin-platelet activation. This presents a promising therapeutic strategy for preventing and treating venous thromboembolism in lung cancer.

Expression of fibroblast activation protein-α in human deep vein thrombosis

BACKGROUND

Fibroblast activation protein-α (FAP), a type-II transmembrane serine protease, is associated with wound healing, cancer-associated fibroblasts, and chronic fibrosing diseases. However, its expression in deep vein thrombosis (DVT) remains unclear. Therefore, this study investigated FAP expression and localization in DVT.

METHODS

We performed pathological analyses of the aspirated thrombi of patients with DVT (n = 14), classifying thrombotic areas in terms of fresh, cellular lysis, and organizing reaction components. The organizing reaction included endothelialization and fibroblastic reaction. We immunohistochemically examined FAP-expressed areas and cells, and finally analyzed FAP expression in cultured dermal fibroblasts.

RESULTS

All the aspirated thrombi showed a heterogeneous mixture of at least two of the three thrombotic areas. Specifically, 83 % of aspirated thrombi showed fresh and organizing reaction components. Immunohistochemical expression of FAP was restricted to the organizing area. Double immunofluorescence staining showed that FAP in the thrombi was mainly expressed in vimentin-positive or α-smooth muscle actin-positive fibroblasts. Some CD163-positive macrophages expressed FAP. FAP mRNA and protein levels were higher in fibroblasts with low-proliferative activity cultured under 0.1 % fetal bovine serum (FBS) than that under 10 % FBS. Fibroblasts cultured in 10 % FBS showed a significant decrease in FAP mRNA levels following supplementation with hemin, but not with thrombin.

CONCLUSIONS

The heterogeneous composition of venous thrombi suggests a multistep thrombus formation process in human DVT. Further, fibroblasts or myofibroblasts may express FAP during the organizing process. FAP expression may be higher in fibroblasts with low proliferative activity.

DNA liquid biopsy-based prediction of cancer-associated venous thromboembolism

Cancer-associated venous thromboembolism (VTE) is a major source of oncologic cost, morbidity and mortality. Identifying high-risk patients for prophylactic anticoagulation is challenging and adds to clinician burden. Circulating tumor DNA (ctDNA) sequencing assays ('liquid biopsies') are widely implemented, but their utility for VTE prognostication is unknown. Here we analyzed three plasma sequencing cohorts: a pan-cancer discovery cohort of 4,141 patients with non-small cell lung cancer (NSCLC) or breast, pancreatic and other cancers; a prospective validation cohort consisting of 1,426 patients with the same cancer types; and an international generalizability cohort of 463 patients with advanced NSCLC. ctDNA detection was associated with VTE independent of clinical and radiographic features. A machine learning model trained on liquid biopsy data outperformed previous risk scores (discovery, validation and generalizability c-indices 0.74, 0.73 and 0.67, respectively, versus 0.57, 0.61 and 0.54 for the Khorana score). In real-world data, anticoagulation was associated with lower VTE rates if ctDNA was detected (n = 2,522, adjusted hazard ratio (HR) = 0.50, 95% confidence interval (CI): 0.30-0.81); ctDNA- patients (n = 1,619) did not benefit from anticoagulation (adjusted HR = 0.89, 95% CI: 0.40-2.0). These results provide preliminary evidence that liquid biopsies may improve VTE risk stratification in addition to clinical parameters. Interventional, randomized prospective studies are needed to confirm the clinical utility of liquid biopsies for guiding anticoagulation in patients with cancer.

Pancreatic Cancer and Venous Thromboembolism

Pancreatic ductal adenocarcinoma (PDAC) accounts for more than 90% of all pancreatic cancers and is the most fatal of all cancers. The treatment response from combination chemotherapies is far from satisfactory and surgery remains the mainstay of curative strategies. These challenges warrant identifying effective treatments for combating this deadly cancer. PDAC tumor progression is associated with the robust activation of the coagulation system. Notably, cancer-associated thrombosis (CAT) is a significant risk factor in PDAC. CAT is a concept whereby cancer cells promote thromboembolism, primarily venous thromboembolism (VTE). Of all cancer types, PDAC is associated with the highest risk of developing VTE. Hypoxia in a PDAC tumor microenvironment also elevates thrombotic risk. Direct oral anticoagulants (DOACs) or low-molecular-weight heparin (LMWH) are used only as thromboprophylaxis in PDAC. However, a precision medicine approach is recommended to determine the precise dose and duration of thromboprophylaxis in clinical setting.

Circulating Tumor Cells and Thromboembolic Events in Patients with Glioblastoma

Patients with glioblastoma (GBM) are at increased risk for arterial and venous thromboembolism (TE). Risk factors include surgery, the use of corticosteroids, radiation, and chemotherapy, but also prothrombotic characteristics of the tumor itself such as expression of tissue factor, vascular endothelial growth factor, or podoplanin. Although distant metastases are extremely rare in this tumor entity, circulating tumor cells (CTCs) have been detected in a significant proportion of GBM patients, potentially linking local tumor growth characteristics to systemic hypercoagulability. We performed post hoc analysis of a study, in which GBM patients had been investigated for CTCs. Information on TE was retrieved from electronic patient charts. In total, 133 patients (median age, 63 years; interquartile range, 53-70 years) were analyzed. During follow-up, TE was documented in 14 patients (11%), including 8 venous and 6 arterial events. CTCs were detected in 26 patients (20%). Four (15%) patients with CTCs had a TE compared with 10 (9%) patients without CTCs. There was no difference in the frequency of TE events between patients with and those without detectable CTCs (p = 0.58). In summary, although our study confirms a high risk of TE in GBM patients, it does not point to an obvious association between CTCs and vascular thrombosis.

Case of Circulating Tumor Cells Discovered in Extensive Deep Venous Thrombosis in a Patient with Known Urothelial Carcinoma

Background

Currently, minimal data are available to explore the composition of venous thromboembolism in patients with cancer. This case report discusses a presentation of venous thromboembolism in a patient with high-grade urothelial carcinoma and highlights the pathology findings in thrombi. Case Presentation. A 55-year-old female who was diagnosed with high-grade urothelial carcinoma with multiple metastases developed an extensive deep vein thrombosis in her left lower extremity. Endovascular revascularization was indicated due to left lower extremity pain and swelling not responsive to anticoagulation. A mechanical thrombectomy was performed, and samples were sent for pathology. Pathologic examination discovered minute fragments of metastatic carcinoma, admixed with laminated blood clots (thrombus). The morphology of metastatic carcinoma and the immunostain profile were compatible with metastatic carcinoma of bladder origin.

Conclusion

Cancer is a well-known risk factor for developing VTEs, and it is estimated that approximately 4-20% of cancer patients will experience VTE at some stage, the rate being the highest in the initial period following diagnosis. Annually, 0.5% of cancer patients will experience thrombosis compared with a 0.1% incidence rate in the general population (Elyamany et al., 2014). Despite knowing the increased incidence of VTEs in cancer patients, there are few studies to date that analyze the composition of thrombi in patients with cancer.

Lung Cancer Related Thrombosis (LCART): Focus on Immune Checkpoint Blockade

Cancer-associated thrombosis (CAT) is a common complication in lung cancer patients. Lung cancer confers an increased risk of thrombosis compared to other solid malignancies across all stages of the disease. Newer treatment agents, including checkpoint immunotherapy and targeted agents, may further increase the risk of CAT. Different risk-assessment models, such as the Khorana Risk Score, and newer approaches that incorporate genetic risk factors have been used in lung cancer patients to evaluate the risk of thrombosis. The management of CAT is based on the results of large prospective trials, which show similar benefits to low-molecular-weight heparins (LMWHs) and direct oral anticoagulants (DOACs) in ambulatory patients. The anticoagulation agent and duration of therapy should be personalized according to lung cancer stage and histology, the presence of driver mutations and use of antineoplastic therapy, including recent curative lung surgery, chemotherapy or immunotherapy. Treatment options should be evaluated in the context of the COVID-19 pandemic, which has been shown to impact the thrombotic risk in cancer patients. This review focuses on the epidemiology, pathophysiology, risk factors, novel predictive scores and management of CAT in patients with active lung cancer, with a focus on immune checkpoint inhibitors.

Cancer-Associated Thrombosis: Epidemiology, Pathophysiological Mechanisms, Treatment, and Risk Assessment

Cancer patients represent a growing population with drastically difficult care and a lowered quality of life, especially due to the heightened risk of vast complications. Thus, it is well established so far that one of the most prominent complications in individuals with cancer is venous thromboembolism. Since there are various improved methods for screening and diagnosing cancer and its complications, the incidence of cancer-associated thrombosis has been on the rise in recent years. Therefore, the high mortality and morbidity rates among these patients are not a surprise. Consequently, there is an excruciating need for understanding the mechanisms behind this complex process, as well as the imperative for adequate analysis and application of the most suitable steps for cancer-associated thrombosis prevention. There are various and numerous mechanisms offering potential answers to cancer-associated thrombosis, some of which have already been elucidated in various preclinical and clinical scenarios, yet further and more elaborate studies are crucial to understanding and preventing this complex and harsh clinical entity. This article elaborates on the growing incidence, mortality, morbidity, and risk factors of cancer-associated thrombosis while emphasizing the pathophysiological mechanisms in the light of various types of cancer in patients and summarizes the most novel therapy and prevention guidelines recommendations.

Crosstalk between Circulating Tumor Cells and Plasma Proteins-Impact on Coagulation and Anticoagulation

Cancer metastasis is a complex process. After their intravasation into the circulation, the cancer cells are exposed to a harsh environment of physical and biochemical hazards. Whether circulating tumor cells (CTCs) survive and escape from blood flow defines their ability to metastasize. CTCs sense their environment with surface-exposed receptors. The recognition of corresponding ligands, e.g., fibrinogen, by integrins can induce intracellular signaling processes driving CTCs' survival. Other receptors, such as tissue factor (TF), enable CTCs to induce coagulation. Cancer-associated thrombosis (CAT) is adversely connected to patients' outcome. However, cancer cells have also the ability to inhibit coagulation, e.g., through expressing thrombomodulin (TM) or heparan sulfate (HS), an activator of antithrombin (AT). To that extent, individual CTCs can interact with plasma proteins, and whether these interactions are connected to metastasis or clinical symptoms such as CAT is largely unknown. In the present review, we discuss the biological and clinical relevance of cancer-cell-expressed surface molecules and their interaction with plasma proteins. We aim to encourage future research to expand our knowledge of the CTC interactome, as this may not only yield new molecular markers improving liquid-biopsy-based diagnostics but also additional targets for better cancer therapies.