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Key Points Cleaved HK is observed in many patients with cancer, suggesting activation of the contact system.EVs from cancer cell lines or patients with cancer express polyphosphate, bind and activate FXII, and are prothrombotic., Visual Abstract, Extracellular vesicles (EV) have been implicated in diverse biological processes, including intracellular communication, transport of nucleic acids, and regulation of vascular function. Levels of EVs are elevated in cancer, and studies suggest that EV may stimulate thrombosis in patients with cancer through expression of tissue factor. However, limited data also implicate EV in the activation of the contact pathway of coagulation through activation of factor XII (FXII) to FXIIa. To better define the ability of EV to initiate contact activation, we compared the ability of EV derived from different cancer cell lines to activate FXII. EV from all cell lines activated FXII, with those derived from pancreatic and lung cancer cell lines demonstrating the most potent activity. Concordant with the activation of FXII, EV induced the cleavage of high molecular weight kininogen (HK) to cleaved kininogen. We also observed that EVs from patients with cancer stimulated FXII activation and HK cleavage. To define the mechanisms of FXII activation by EV, EV were treated with calf intestinal alkaline phosphatase or Escherichia coli exopolyphosphatase to degrade polyphosphate; this treatment blocked binding of FXII to EVs and the ability of EV to mediate FXII activation. In vivo, EV induced pulmonary thrombosis in wild-type mice, with protection conferred by a deficiency in FXII, HK, or prekallikrein. Moreover, pretreatment of EVs with calf intestinal alkaline phosphatase inhibited their prothrombotic effect. These results indicate that polyphosphate mediates the binding of contact factors to EV and that EV-associated polyphosphate may contribute to the prothrombotic effects of EV in cancer.

Metastatic renal cell carcinoma (mRCC) is associated with a high risk of thromboembolism (TE). We investigated whether immunotherapy (IO) increases the hypercoagulable state in this high-risk population. Patients with mRCC treated with IO between 1 January 2015 and 31 December 2019 at the Cleveland Clinic were identified. Cumulative incidence analysis calculated TE rates over time and Gray’s test determined differences in TE rates among groups. The Kaplan–Meier method estimated survival, while Cox proportional hazard regression evaluated the impact of TE on OS. Of 351 patients, 75% were men with clear cell mRCC (81%) and International Metastatic Renal Cell Carcinoma (IMDC) intermediate- to poor-risk disease (77%). Patients received single-agent IO (52%), doublet IO (31%), or IO with non-IO therapy (17%). The median number of IO doses was 8 (range 1–81). At a median follow-up of 12.8 months, 12% of patients (n = 43) had a TE event (venous n = 37 [11%], arterial n = 6 [2%]). The cumulative TE incidence at 6 months was 4.4% (95% confidence interval [CI] 2.6–6.9) and 9.8% (95% CI 6.8–13.4) at 12 months. No factors, including IMDC or Khorana score, were identified to predict TE development. Seventy-two percent of TE resulted in hospitalization (9% TE-related mortality and 21% TE-related dose delay). TE (p

Cancer patients have an increased risk of developing venous thrombosis. The implementation of a cancer associated thrombosis clinic can be instrumental for the prevention, early recognition, and management of venous thromboembolism in this vulnerable population. Cancer thrombosis clinics rely on a multidisciplinary approach to care and require standardization along with a dedicated team of healthcare professionals. Cancer thrombosis clinics have the potential to improve patient outcomes and lower healthcare expenditure. Herein, we describe a successful model of a cancer thrombosis clinic and highlight the potential impact on clinical outcomes.

Cancer patients have an increased risk of developing venous thrombosis. The implementation of a cancer associated thrombosis clinic can be instrumental for the prevention, early recognition, and management of venous thromboembolism in this vulnerable population. Cancer thrombosis clinics rely on a multidisciplinary approach to care and require standardization along with a dedicated team of healthcare professionals. Cancer thrombosis clinics have the potential to improve patient outcomes and lower healthcare expenditure. Herein, we describe a successful model of a cancer thrombosis clinic and highlight the potential impact on clinical outcomes.

The current American Society of Hematology (ASH) guidelines for the management of patients with immune thrombocytopenic purpura (ITP) are an update to the 2011 guidelines. The updates focus on treating patients with ITP without bleeding in both outpatient and inpatient settings, including those with newly diagnosed, persistent, and chronic ITP refractory to first-line therapy. Recommendations for therapy include corticosteroids, intravenous immunoglobulins, anti-D immunoglobulin, rituximab, splenectomy, and thrombopoietin-receptor agonists, as well as observation.

Background: The relationship between venous thromboembolism (VTE) and lymphoma is well established. In recent years, direct oral anticoagulants (DOACs) have been adopted as a treatment option for cancer associated thrombosis, however the majority of data using DOACs is in solid tumor patients. Here, we report the risk of recurrent VTE, bleeding outcomes, and effect of VTE on survival among lymphoma patients treated in a large centralized cancer associated thrombosis clinic. Methods: We prospectively followed lymphoma patients referred to our clinic from 8/2014-01/2021. VTE events including deep venous thrombosis (DVT), pulmonary embolism (PE), and visceral vein thrombosis (VVT), were noted. Overall survival (OS) was estimated by Kaplan-Meier and compared using log rank test. Cumulative incidence rate of VTE was estimated and compared using Gray's method. Results: A total of 103 patients were referred to our clinic due to clinical suspicion of VTE, of whom 40 (38.8%) were diagnosed with an acute VTE. The median age of the study population was66 (range 19-88), 61.2% were male and 16.5% had prior VTE. Non-Hodgkin Lymphoma (NHL) compromised 87.4%, with diffuse large b-cell lymphoma (DLBCL) being the most common subtype. Most patients had stage 4 disease (55.34%), had high grade lymphoma (defined as grade 3-4) (51.46%), and were on antineoplastic treatment (71.67%) at the time of VTE diagnosis. Site of VTE was DVT in 35.9%, PE in 5.8%, both DVT and PE in 2.9% and VVT in 0.97% of patients. Of these, 21 (20.39%) received a (DOAC), 14(13.59%) received enoxaparin, and 2(1.94) had IVC filter placed due to contraindication to anticoagulation. VTE recurrence occurred in 10% patients (total n=4; 2 were on enoxaparin and 2 were on rivaroxaban). Cumulative incidence of VTE in all patients at 6 months was 1% (95% CI: 0-2.9%), at 1 year was 3% (95% CI: 0-6.4%) with no significant difference in VTE or bleeding rates between lymphoma types or grade groups (P >0.05) (Table 1). Of 37 patients on anticoagulation, 10.8% experienced bleeding events (n=4) , of which 1 (2.7%) had major bleeding on IVC filter and 3 (8.1%) had CRNMB (2 on enoxaparin and 1 on rivaroxaban) at 6 month follow-up. Median follow-up was 35.9 months (range: 0.4-77.7 months) and median 2 year OS was 76%, 95% CI (68-85%). Overall survival was negatively impacted by age (patients over age 65 had a 2 year OS rate of 67%95% CI (0.56-0.81), p=0.01). Lymphoma grade had no impact on OS (2-year OS rate= 0.69, 95% CI (0.57-0.84), P=0.1132) Conclusion: High grade and low grade lymphoma patients treated in our centralized cancer thrombosis clinic had a 10% chance of VTE recurrence when treated with DOAC or enoxaparin. Bleeding rates were low in both groups; however, we saw decreased overall survival in those treated with DOACs. This data adds to the growing knowledge of treating hematologic malignancies with direct oral anticoagulants, but larger studies are needed to study the safety and efficacy of these agents in lymphoma patients. Figure 1 Figure 1. Disclosures Khorana: Halozyme: Consultancy, Honoraria; Anthos: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Bayer: Consultancy, Honoraria. Angelini: Sanofi: Membership on an entity's Board of Directors or advisory committees.

Introduction Venous thromboembolism (VTE) is a common complication of both solid and hematologic malignancies. Risk factors for VTE and standard recommendations for prevention and treatment primarily pertain to solid tumor patients. There are fewer data in patients who have undergone allogeneic hematopoietic cell transplant (HCT). Therefore, we studied the incidence, risk factors, and impact of VTE on post-HCT outcomes. Methods We retrospectively reviewed 431 patients who underwent allogeneic HCT between 1/2014 and 8/2019 to identify patients with VTE. VTE was estimated with cumulative incidence methods. Risk factors for VTE were identified with Fine and Gray regression and results are reported as hazard ratio (HR) with a 95% confidence interval (CI). An apriori list of potential risk factors for VTE included age, gender, race, performance status, co-morbidity index, number of prior chemotherapy regimens, history of VTE, disease risk, donor/graft source, transplant conditioning regimen, and acute or chronic graft vs. host disease (GVHD). VTE was analyzed as a time-dependent covariate relative to other post-HCT outcomes. Results Patient characteristics are shown in the Table. The median age at time of transplant was 59 years, (range 18-76); 55.5% were male, the majority (90.7%) were White. The most common indication for transplant was acute myelogenous leukemia and myelodysplastic syndrome (70.3%). Within our cohort, 64 patients (14.8%) developed VTE after allogeneic HCT. The cumulative incidence of VTE at 1 year was 9% (CI 7-12%). Median time to VTE was 9.8 months (range 0.7-74.0) (Figure). Thrombosis site breakdown included the following: lower deep vein thrombosis (DVT) n=47 (74%), catheter related DVT n=12 (19%), DVT and pulmonary embolism (PE) n=12 (19%), PE alone n=4 (6%). Patients were most commonly treated with a direct oral anticoagulant (n=27, 42%), followed by enoxaparin (n=15, 23.4%). The majority of patients (n=38, 58%) were treated with anticoagulation for more than 6 months. Six (9.4%) patients had recurrent thrombosis after completion of anticoagulation therapy from the time of transplant until last known follow-up. Only 9 (14%) had an inferior vena cava filter placed due to contraindications for anticoagulation. In patients treated with anticoagulation, there was a low overall incidence of clinically significant bleeding (n=3, 5%). In multivariable analysis, age (HR 1.36 per 10-year increase, CI 1.09-1.70, P=0.006), history of VTE (HR 1.95, CI 1.09-3.48, P=0.024), and grade 2-4 acute GVHD (HR 1.75, CI 1.05-2.94, P=0.033) were significantly associated with VTE. VTE was not associated with relapse mortality (HR 0.95, CI 0.44-2.04, P=0.89), however VTE was significantly associated with an increased risk of non VTE-associated non-relapse mortality (NRM) (HR 4.09, CI 2.47-6.74, P Discussion VTE is an important complication after allogeneic HCT and is associated with significantly increased NRM and inferior OS. Older patients, those with a prior history of VTE, and patients with acute GVHD are at increased risk for development of VTE after HCT. We found an overall low risk of bleeding with anticoagulation and further study to investigate the role of prophylaxis in this high-risk cohort is needed. Figure 1 Figure 1. Disclosures Sobecks: CareDX: Membership on an entity's Board of Directors or advisory committees. Majhail: Incyte Corporation: Consultancy; Anthem, Inc: Consultancy. Angelini: Sanofi: Membership on an entity's Board of Directors or advisory committees. Hamilton: Syndax: Membership on an entity's Board of Directors or advisory committees; Equilium: Membership on an entity's Board of Directors or advisory committees.