Abstract: In the Hokusai VTE Cancer study, edoxaban was non-inferior to dalteparin for the composite outcome of recurrent venous thromboembolism (VTE) and major bleeding in 1,050 patients with cancer-associated VTE. The absolute rate of recurrent VTE was 3.4% lower with edoxaban, whereas the absolute rate of major bleeding was 2.9% higher. The present analysis focuses on the sites, clinical presentation, course and outcome of bleeding events, and the associated tumour types. Major bleeds and their severity (categories 1–4) were blindly adjudicated by a committee using a priori defined criteria, and data were analysed in the safety population. Major bleeding occurred in 32 of 522 patients given edoxaban (median treatment duration, 211 days) and in 16 of 524 patients treated with dalteparin (median treatment duration, 184 days); no patients had more than one major bleed. There were no fatal bleeds with edoxaban, and two with dalteparin. Severe bleeding at presentation (category 3 or 4) occurred in 10 (1.9%) and 11 (2.1%) patients in the edoxaban and dalteparin groups, respectively. The excess of major bleeding with edoxaban was confined to patients with gastrointestinal cancer. However, severe major bleeding at presentation (category 3 or 4) in this sub-group occurred in 5 of 165 (3.0%) and in 3 of 140 (2.1%) patients given edoxaban or dalteparin, respectively. In conclusion, this analysis suggests that while oral edoxaban is an appropriate alternative to subcutaneous dalteparin for treatment of cancer-associated VTE, the use of edoxaban in patients with gastrointestinal cancer requires careful benefit–risk weighting.

Abstract: On behalf of the Hokusai VTE Cancer Investigators The treatment of cancer-associated venous thromboembolism (VTE) is challenging because these patients are at increased risk of both recurrent VTE and major bleeding. Low-molecular-weight heparin (LMWH) treatment is standard care for these patients, but requires daily subcutaneous injections. Guidelines recommend LMWH treatment for 6 months, but the risk-benefit beyond this time is uncertain. Direct oral anticoagulants are used for the treatment of VTE in patients without cancer, but their role in patients with cancer- associated VTE is uncertain. In this randomized, open-label non-inferiority trial, cancer patients with acute symptomatic or incidental VTE were assigned to receive LMWH for a minimum of 5 days followed by the oral factor Xa inhibitor edoxaban at a dose of 60 mg once daily (or 30 mg once daily in patients with a creatinine clearance of 30 to 50 ml per minute or a body weight below 60 kg), or subcutaneous dalteparin 200 units per kg once daily for one month followed by 150 units per kg thereafter. Patients received these regimens for up to 12 months. The primary outcome was the composite of the first recurrent VTE or major bleeding event during follow-up for 12 months. Secondary outcomes included recurrent VTE and major bleeding analyzed separately, and survival free of recurrent VTE or major bleeding. The study hypothesis was that edoxaban would be noninferior to dalteparin for the primary outcome with an upper 95% confidence interval [CI] for the hazard ratio below 1.5, and a two-sided alpha of 0.05. All outcomes were independently adjudicated by a committee without knowledge of treatment allocation. This committee also assessed the clinical severity of major bleeding events using categorical criteria defined a priori (categories 1 to 4). From July 2015 through December 2016 a total of 1050 patients were enrolled at 114 centers in 13 countries; 525 were randomized to edoxaban and 525 to dalteparin. At entry, pulmonary embolism with or without deep-vein thrombosis was present in 657 patients (63%) while the remainder had isolated deep-vein thrombosis. Of the 1050 patents, 706 (67%) had symptomatic VTE and the rest were incidental. Active cancer at entry was present in 97% of the patients and 53% had metastatic disease. 1046 patients were included in the modified-intention-to-treat analysis. The primary outcome occurred in 67 of 522 patients (12.8%) in the edoxaban group compared with 71 of 524 patients (13.5%) in the dalteparin group (hazard ratio with edoxaban, 0.97; 95% CI, 0.70 to 1.36; P = 0.0056 for noninferiority) for a risk difference (edoxaban minus dalteparin) of - 0.7% (95% CI, - 4.8 to 3.4). The difference in risk for recurrent VTE was -3.8 % (95% CI, -7.1 to -0.4), whereas the corresponding difference in risk for major bleeding was 3.1% (95% CI, 0.5 to 5.7). The frequencies of severe major bleeding events (categories 3 and 4) were similar during treatment with edoxaban or dalteparin (12 patients in each group respectively). Survival at 12 months free of recurrent VTE and major bleeding in the edoxaban and dalteparin groups was similar (55.0% and 56.5% respectively). Oral edoxaban for up to 12 months is noninferior to subcutaneous dalteparin for the treatment of cancer-associated VTE. Disclosures Raskob: BMS: Consultancy, Honoraria; Eli Lilly: Consultancy; Janssen: Consultancy; Johnson and Johnson: Consultancy; Pfizer: Consultancy, Honoraria; Portola: Consultancy; Boehringer-Ingelheim: Consultancy; Medscape: Honoraria; Bayer Healthcare: Consultancy; Daiichi Sankyo: Consultancy, Honoraria. Van Es:Daiichi Sankyo: Honoraria; Pfizer: Honoraria. Verhamme:Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Bayer Healthcare: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Boehringer Ingelheim: Consultancy, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Portola: Consultancy; Medscape: Honoraria; Leo: Honoraria, Research Funding; Sanofi Aventis: Research Funding; Medtronic: Honoraria, Membership on an entity's Board of Directors or advisory committees. Carrier:Daiichi Sankyo: Consultancy, Honoraria; BMS: Consultancy, Research Funding; Leo: Consultancy, Research Funding; Pfizer: Consultancy, Honoraria. Di Nisio:Daiichi: Consultancy, Honoraria. Garcia:Daiichi Sankyo: Honoraria, Research Funding; BMS: Consultancy; Boehringer Ingelheim: Consultancy; Janssen: Consultancy, Research Funding; Pfizer: Consultancy, Honoraria; Medscape: Honoraria; Incyte: Consultancy, Honoraria, Research Funding. Grosso:Daiichi Sankyo: Employment. Kakkar:Daiichi Sankyo: Consultancy, Honoraria; Bayer Healthcare: Consultancy, Research Funding; Boehringer Ingelheim: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Sanofi SA: Consultancy, Honoraria; Verseon: Consultancy, Honoraria. Kovacs:Daiichi Sankyo: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Bayer: Honoraria; Bristol Myers Squibb: Research Funding. Mercuri:Daiichi Sankyo: Employment, Patents & Royalties: pending properties of edoxaban . Meyer:BMS Pfizer: Research Funding; Leo: Other: travel support; Stago: Other: travel support. Segers:Ionis: Research Funding; Daiichi Sankyo: Research Funding; Janssen: Research Funding. Shi:Daiichi Sankyo: Employment. Wang:Daiichi Sankyo: Honoraria. Yeo:Daiichi Sankyo: Honoraria, Research Funding; Bayer Healthcare: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Boehringer Ingelheim: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Leo: Consultancy, Honoraria. Zhang:Daiichi Sankyo: Employment. Zwicker:Daiichi Sankyo: Honoraria; Quercegen Pharma: Research Funding; Parexel: Consultancy. Weitz:Daiichi-Sankyo: Consultancy, Honoraria; Ionis Pharmaceuticals: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Novartis Pharmaceuticals: Consultancy, Honoraria; Merck & Co., Inc.: Consultancy, Honoraria; Pfizer, Inc.: Consultancy, Honoraria; Portola Pharmaceuticals: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Medscape: Consultancy, Honoraria; Boehringer Ingelheim: Consultancy; Bayer HealthCare Pharmaceuticals: Consultancy, Honoraria. Büller:Daiichi Sankyo: Consultancy, Honoraria; Bayer: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Boehringer Ingelheim: Consultancy, Honoraria; Portola: Consultancy; Medscape: Honoraria; Eli Lilly: Consultancy; Sanofi Aventis: Consultancy; Ionis: Consultancy.

Abstract: Heparin thromboprophylaxis is routinely administered during hospitalization for COVID-19. Because of the immune stimulation related to COVID-19, there is ongoing concern regarding a heightened incidence of heparin-induced thrombocytopenia (HIT). We performed a literature search using PubMed, EMBASE, Cochrane, and medRxiv database to identify studies that reported clinical and laboratory characteristics and/or the incidence of HIT in patients with COVID-19. The primary aim was to systematically review the clinical features and outcomes of patients with COVID-19 with confirmed HIT. The secondary objective was to perform a meta-analysis to estimate the incidence of HIT in hospitalized patients with COVID-19. A meta-analysis of 7 studies including 5849 patients revealed the pooled incidence of HIT in COVID-19 of 0.8% (95% confidence interval [CI], 0.2%-3.2%; I2 = 89%). The estimated incidences were 1.2% (95% CI, 0.3%-3.9%; I2 = 65%) vs 0.1% (95% CI, 0.0%-0.4%; I2 = 0%) in therapeutic vs prophylactic heparin subgroups, respectively. The pooled incidences of HIT were higher in critically ill patients with COVID-19 (2.2%; 95% CI, 0.6%-8.3%; I2 = 72.5%) compared with noncritically ill patients (0.1%; 95% CI, 0.0%-0.4%: I2 = 0%). There were 19 cases of confirmed HIT and 1 with autoimmune HIT for clinical and laboratory characterization. The median time from heparin initiation to HIT diagnosis was 13.5 days (interquartile range, 10.75-16.25 days). Twelve (63%) developed thromboembolism after heparin therapy. In conclusion, the incidence of HIT in patients with COVID-19 was comparable to patients without COVID-19, with higher incidences with therapeutic anticoagulation and in critically ill patients.

Abstract: Background Protein disulfide isomerase (PDI) is a thiol isomerase secreted by platelets and endothelial cells and is required for thrombus formation. We previously showed that quercetin flavonoids inhibit PDI and block thrombus formation following vascular injury in a mouse model. Quercetins are present in a wide range of fruits and vegetables and epidemiologic data suggest an antithrombotic effect. Initial human studies demonstrated that the oral administration of isoquercetin reduces PDI activity in plasma. To evaluate the antithrombotic strategy of inhibiting PDI, we performed a phase II trial to evaluate the efficacy of isoquercetin to reduce the hypercoagulability of cancer patients at high risk for venous thromboembolism (VTE). In high-risk cancer cohorts with protocol-mandated screening for VTE, the reported incidence of VTE often exceeds 20% within months of initiation of chemotherapy. The risk of major hemorrhage is also higher in patients with advanced cancer which complicates the decision to recommend thromboprophylaxis. Methods We performed a phase II study at 11 sites to assess the safety and efficacy of isoquercetin in cancer patients at high risk for VTE. Cohort A received isoquercetin 500 mg daily and Cohort B received 1000 mg isoquercetin daily for 56 days with laboratory assays performed at the beginning and at completion of study. Eligible patients had locally advanced or metastatic pancreatic, non-small cell lung, or colorectal cancer and enrolled within 4 weeks of initiating first or second line chemotherapy. The primary endpoint of the study was a reduction in D-dimer at day 56. Patients were monitored for the development of venous thromboembolism including a protocol-required bilateral lower extremity ultrasound performed at day 56. The primary VTE endpoint was defined as any symptomatic proximal or distal lower extremity DVT, symptomatic pulmonary embolism or fatal PE, or asymptomatic proximal DVT diagnosed by screening compression ultrasound. Radiology images for all suspected VTE were centrally reviewed and adjudicated by an independent committee. Results There were no primary VTE endpoints observed in either cohort. Paired plasma samples were analyzed in 25 patients who received isoquercetin 500 mg daily (Cohort A) and 21 patients who received the isoquercetin 1000 mg daily (Cohort B). For the primary D-dimer endpoint, the administration of isoquercetin 1000 mg decreased D-dimer plasma concentrations by a median of 20% equating to a median decrease of 206 ng/ml fibrinogen equivalent units (P 〈 0.001). The administration of isoquercetin 500 mg did not affect plasma D-dimer levels at 56 days (median change +9.90%, P=0.93). In both cohorts we measured an increase in PDI inhibition in plasma at day 56 (cohort A median increase 46%, P 〈 0.001; cohort B median increase 78%, P 〈 0.001). Corroborating the antithrombotic efficacy of the 1000 mg dose, we also observed a significant decrease in circulating soluble P-selectin (median decrease 58%, P 〈 0.001) and platelet-dependent thrombin generation (median decrease 55%, P=0.006) as shown in the Figure. Isoquercetin did not prolong the PT or PTT. There were two grade 1 hemorrhoidal bleeds and no major hemorrhages observed. Conclusions The oral flavonoid, isoquercetin, prevented venous thromboembolism in cancer without an observed increase in hemorrhage. These results represent the first evidence in humans that targeting extracellular PDI has antithrombotic efficacy in a high VTE-risk population and implicate PDI-targeted therapies as a new class of antithrombotic therapeutics. (Clinicaltrials.gov #NCT02195232). Figure Figure. Disclosures Zwicker: Daiichi: Honoraria; Quercegen: Research Funding; Parexel: Consultancy; Incyte: Research Funding.

Abstract: A major challenge in the development of effective myeloma (MM) therapy is addressing tumor heterogeneity, with the presence of sub-clones that exhibit resistance to standard therapy. An ongoing area of investigation focuses on identification of myeloma initiating cells that demonstrate greater capacity for self-renewal and serve as a potential reservoir for disease recurrence. It has been postulated that MM cells arise from a primitive B cell precursor population distinct from the more differentiated malignant plasma cell population. The critical feature of these myeloma-propagating cells is thought to be the ability to efficiently recapitulate MM in immunocompromised mice. MUC1 is an oncoprotein aberrantly expressed in malignant cells, including multiple myeloma, that interacts with multiple transcription factors, such as NF-κB and the β-catenin/TCF4 complex, that regulate cell survival and proliferation critical for malignant transformation. We have previously demonstrated that MUC1 is expressed by AML leukemic blasts, as compared to normal hematopoietic stem cells, and blockade of MUC1 signaling prevents establishment of leukemia in immunocompromised animals. In the present project, we identify a unique population of CD34+/MUC1+/CD138+/CD20+ cells in primary MM bone marrow samples that exhibit features of myeloma initiating cells, as manifested by high levels of enzymatic ALDH activity, the ability to efflux Hoechst dye represented as “side population” (SP), and the ability to establish disease in immunocompromised mice. Of note, MM engraftment of unselected primary myeloma cells in a xenograft model has a low success rate, and typically requires the introduction of an artificial stromal support network. Methods and results Bone marrow aspirates were obtained from newly diagnosed MM patients using an established protocol approved by the IRB. Expression of MUC1, myeloid and lymphoid markers was assessed using multicolor flow cytometric analysis. While MUC1 shows only a minimal expression ( 〈 5%, n=8) in normal CD34+ hematopoietic progenitors, we have demonstrated that on average 54% of CD34+ cells isolated from bone marrow samples of MM patients expressed MUC1 (n=7, p 〈 0.05), in addition to other MM and lymphoid markers. MM derived CD34+MUC1+ cells segregated with SP by the ability to efflux Hoechst dye and expressed high levels of ALDH as assessed by the Aldefluor assay (11% of CD34+MUC+ cells had high ALDH activity as opposed to less than 1% in bulk MM marrow cells, n=3). CD34+MUC+ cells co-expressed CD138+, CD20+, and were CD38 dim (n=7), consistent with the phenotypic markers that have been previously described in association with myeloma propagating cells. In order to study the capacity of CD34+MUC1+ cells to recapitulate MM in a murine model, a bone marrow sample was obtained from a patient with newly diagnosed MM with a cytogenetic abnormality characterized by the rearrangement of the CCND1/IGH loci. Primary bone marrow cells were fluorescently labeled and CD34-MUC+ (consistent with mature CD138+CD38hi plasma cells) and CD34+MUC+ populations of cells were isolated using FACS sorting. Cells from each population were injected into an irradiated NOD/SCID mouse (0.5x106cells/mouse). After 13 weeks, no human engraftment was detected in the 4/4 mice injected with CD34-MUC+ population of mature plasma cells. In contrast, 2/2 mice injected with CD34+MUC+ cells demonstrated human engraftment. Engrafted cells were isolated by FACS sorting and transferred onto glass slides for cytogenetic analysis by FISH. Notably, the engrafted cells harbored rearrangement at CCND1/IGH loci consistent with the originating MM clone. In another experiment, 2/2 NOD/SCID mice inoculated with CD34+MUC1+ primary MM cells demonstrated MM engraftment after 12 weeks, characterized by the presence of CD138+CD45- human plasma cells in the murine bone marrow. Conclusions We have identified a subpopulation of primitive myeloma cells that coexpress CD34 and the MUC1 oncoprotein. CD34+MUC1+ cells express CD20 and CD138, and express high levels of ALDH. CD34+MUC1+ cells demonstrate the capacity to engraft human MM cells in immunocompromised mice, even without an artificial stromal framework. Inhibition of MUC1 signaling thus may offer new avenues to target critical myeloma subclones. Disclosures: No relevant conflicts of interest to declare.