McBane, Robert D.

Abstract Background An increasing number of patients (pts) requiring anticoagulation are treated with oral factor Xa inhibitors (DOAC) as an alternative to vitamin K antagonists. Prior to the recent approval of coagulation factor Xa (recombinant), inactivated-zhzo in May 2018, four factor prothrombin complex concentrates (4PCC) have been used to reverse the effects of DOACs. We retrospectively analyzed our institutional experience with 4 PCC for reversal of apixaban and rivaroxaban to determine the indications for 4PCC use and outcomes. Methods After IRB approval, pts receiving 4PCC, from Feb 2016 to January 2018 were identified from our pharmacy database and pts receiving PCC for reversal of apixiban and rivaroxaban were selected. Consenting pts medical records (MR) were reviewed for demographics and indications for DOAC and 4PCC as well as outcomes of 4PCC use. Pts were excluded if they had discontinued DOAC greater than 7 days before receiving 4PCC or if they were started on alternative forms of anticoagulation at a therapeutic dose prior to receiving PCC. Primary endpoint was clinical efficacy (clinical improvement or stability) or ability to undergo required procedure) and secondary endpoint was safety (thromboembolism and death) up to 35 days post-infusion of 4PCC. Stability for intracranial hemorrhages (ICH) was determined by clinical improvement and if head imaging performed, no change in head CT or MRI scan, whereas stability for other bleeds was determined by hemoglobin stability and opinions of providers in the MR. Primary efficacy outcome for pts undergoing surgery was based on MR comments by the performing surgeon and use of other hemostatic agents and red blood cell transfusions. Results 49 (32 male) pts, median age of 74 (31-95) years, met our study criteria and received 4PCC for reversal of apixaban (n=29) and rivaroxaban (n=20). Indications for anticoagulation were atrial fibrillation (n=35) and thrombosis (n=14). Of the 14 pts with thrombosis, 11 had deep vein thrombosis while 3 had thrombosis at other sites (arterial graft thrombus, aortic thrombus, and portal vein thrombosis). 4PCC was administered in the emergency department (n=36), intensive care unit (n=10), or the general medical wards (n=3). Indications for 4PCC included bleeding (n=40), procedure/surgery (n=6), and hemodynamic instability with clinical suspicion for bleeding (n=3). Bleeding location is reported in table 1. All procedure/surgery performed for clinical symptoms not related to hemorrhage were non-elective procedures and included exploratory laparotomy (n=4), laparoscopic cholecystectomy (n=1), and incision and drainage of abdominal wall abscess (n=1). Median PCC dose was 42 (10.3-63.3) IU/kg. Outcomes 32/40 (80%) pts had stability or an improvement in bleeding, while 5 pts had bleeding that did not improve. 3 pts, all with ICH, had a bleed that worsened 8 (6-8) hours after PCC but then spontaneously stabilized 24 (8-24) hours later. Of those presenting with clinical bleeding, 3 pts received FFP within 3 hours prior to treatment with 4PCC, 2 pts received FFP within 12 hours after 4PCC, and 2 pts received FFP within 3 hours before and 12 hours after 4PCC. Of 40 pts receiving PCC for bleeding, 14 also had a procedure to help achieve hemostasis (Table 2). All 6 pts were able to undergo procedure/surgery. 5/6 patients achieved adequate hemostasis. One pt had no mention of unanticipated bleeding in the MR but received 8 units of FFP intraoperatively after 4PCC. 6/49 (12%) pts had a thrombotic complication within 35 days of receiving PCC (median 4 days; (range 1-31) including arterial graft thrombus (n=1), superficial venous thrombus (n=1), bilateral soleal vein thrombosis (n=1), internal jugular vein and innominate vein thrombosis (n=1) stroke (n=1), and progression of preexisting portal vein thrombosis (n=1). All-cause mortality was 20%. 3/10 deaths were in pts who never achieved neurologic recovery after ICH and one pt had stroke-like symptoms leading to death 30 days after 4PCC (administered for ICH). Conclusion In this cohort, 80% of pts demonstrated clinical stability/improvement of hemorrhage. All pts were able to undergo surgical procedures; however 17% required additional FFP to achieve hemostasis. Thromboembolism occurred in 12% of patients. No deaths could definitely be attributed to 4PCC; however, 30% of deaths could be attributable to the underlying hemorrhagic episode. Disclosures No relevant conflicts of interest to declare.

Abstract Background: Gastric cancer is one of the most pro-thrombotic tumor types, and after accounting for prevalence, it may be responsible for a significant burden of cancer-associated venous thromboembolism (VTE). Patients with gastric cancer are also at high risk for gastrointestinal bleeds (GIB), making primary thromboprophylaxis and anticoagulation an ongoing treatment challenge. Due to these competing risks, patients with gastric cancer may not be eligible for clinical trials of thromboprophylaxis and treatment of cancer-associated VTE. Additional information regarding the severity and outcomes of both gastrointestinal hemorrhage and VTE in patients with gastric cancer would be useful to guide clinical decision-making. Aim: To determine the annual rates, inpatient mortality, length of stay and cost of VTE- and GIB-related admissions in patients with gastric cancer. Methods: We queried the 2009-2014 Nationwide Inpatient Sample (NIS) database, a nationally weighted hospital admissions database developed for the Healthcare Cost and Utilization Project, to identify adults (age ≥ 18 years) hospitalized with gastric cancer. Hospitalizations in which VTE or GIB were among the top-five discharge diagnoses, were considered an admission complicated by one of these events. In-hospital outcomes of patients with VTE were compared to those with GIB. We used linear regression models to analyze trends in outcomes over time and binary logistic regression with forward modeling to identify predictors of inpatient mortality. All statistical analyses were conducted with SPSS, version 24 (IBM, Armonk, NY). Results: Among a total of 253,680 admissions with gastric cancer, 17,831 (6.7%) experienced a GIB whereas 10,992(4.2%) had VTE. Of those patients who experienced VTE, the majority (49.7%) developed pulmonary embolism, followed by lower extremity deep vein thrombosis (41.8%) and upper extremity deep vein thrombosis (8.54%). The patients included in this study were mainly white (53.7%) men (63.6%) with a median age of 67 (IQR:20) years; and a mean of 6 (SD: 2.83) chronic medical conditions. The annual GI bleed rate remained stable during the study period (16% in 2009 to 17.2% in 2014: p = 0.67) with a significant downtrend in inpatient mortality (18.8% in 2009 to 13.7% in 2014: p <0.01). In contrast, the annual rates of VTE-related admissions showed a small but significant uptrend (15% in 2009 to 18.1% in 2014: p <0.01) and an uptrend in the inpatient mortality during the study period (15.7% in 2009 to 19.2% in 2014: p <0.01). The overall inpatient mortality was higher among patients with VTE than with GI bleeds (10.2% vs 6.5%, p < 0.01; OR univariate: 1.51, CI: 1.42 - 1.61, p < 0.01). The negative effect of VTE on inpatient mortality persisted after adjusting for possible confounders such as metastatic disease, several comorbidities and demographics (OR: 1.39, CI: 1.30 - 1.49, p < 0.01). The VTE-associated admissions had a slightly longer length of stay (median, 6 vs 4 days, p < 0.01) with a significantly higher cost compared to GI bleed ($45,599 vs $31,219, respectively, p < 0.01). Conclusion: In this NIS cohort of hospitalized patients with gastric cancer, GIB was more frequently observed than VTE, but those with VTE had higher inpatient mortality, longer length of stay, and higher hospital costs. Clinicians should be aware of patient-specific risk factors for both VTE and GI bleed and take these factors into account when discussing VTE prophylaxis and treatment with patients. Future studies should look to identify those patients with gastric cancer who would benefit most from primary VTE prophylaxis as well as identify ideal agents for the treatment of gastric cancer-associated VTE. Figure. Figure. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 3404 Background: Appropriate periprocedural management of the chronically-anticoagulated patient with an inherited or acquired thrombophilia is uncertain. Objective: To estimate the 3-month cumulative incidence of thromboembolism (TE) and major bleeding and test thrombophilia as a potential predictor of these outcomes among chronically-anticoagulated patients undergoing a procedure. Methods: 2182 consecutive patients referred to the Mayo Thrombophilia Center for standardized peri-procedural anticoagulation management were followed for TE, major bleeding and survival. The three-month cumulative incidence rates for TE, major bleeding and death were estimated by Kaplan-Meier analyses. For each chronic anticoagulation indication, we tested “strong” thrombophilia (antithrombin, protein C or protein S deficiency, homozygous or combined heterozygous Factor V Leiden or prothrombin G20210A), ”weak” thrombophilia (heterozygous Factor V Leiden or prothrombin G20210A), lupus anticoagulant/antiphospholipid antibodies and bridging heparin as potential predictors of TE and major bleeding using Cox proportional hazards modeling. Results: Patients with thrombophilia tended to be younger with a slight female predominance. Compared to no thrombophilia, thrombophilia patients (n=202; 143 bridged with heparin) had similar rates of venous (0% vs. 0.5%; p=0.34) and arterial (0.5% vs. 0.5%; p=0.94) thromboembolism, major bleeding (2.0% vs. 2.0%; p=0.97) and mortality (1.5% vs. 2.2%; p=0.52). Among thrombophilia patients, the TE and major bleeding rates were similar for strong (n=29) or weak thrombophilia (n=99), or lupus anticoagulant/antiphospholipid antibodies (n=74). Similarly, among thrombophilia patients, bridging heparin did not affect the rates of major bleeding (2.1% vs. 1.7%; p=0.85) or TE (0.7% vs. 0%, p=0.52). Conclusions: Inherited or acquired thrombophilia does not appear to impact the rates of TE, major bleeding or mortality after temporary interruption of chronic anticoagulation for an invasive procedure. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 491 Introduction: Chronically-anticoagulated patients with active cancer (Ca) often require temporary interruption of warfarin for an invasive diagnostic or therapeutic procedure. While such patients may be at increased risk for periprocedural thromboembolism and bleeding, there are virtually no estimates of these outcomes among Ca patients or the most appropriate periprocedural anticoagulation management. The aims of this study were to estimate rates of these outcomes among Ca patients and to test active cancer and “bridging” low molecular weight heparin (LMWH) as potential predictors of these outcomes. Patients and Methods: In a retrospective cohort study, all chronically-anticoagulated patients referred to the Mayo Clinic Thrombophilia Center for periprocedural anticoagulation management over the 11-year period, 1997-2007, were followed forward in time for the outcomes of venous and arterial thromboembolism (VTE; ATE), major bleeding and vital status within 3 months of consultation. Warfarin was stopped 4-5 days prior to the procedure and patients received bridging LMWH according to the estimated risk of thromboembolism and bleeding. All outcome events were centrally adjudicated using pre specified criteria. Results: The total cohort (n=2517) included 500 patients with Ca. Chronic anticoagulation indications included prior VTE (n=1033), mechanical heart valve (n=669), atrial fibrillation (n=530) and other (mainly vascular bypass; n=285). 65% and 64% of patients with and without Ca received bridging LMWH, respectively. Prior VTE was more common among Ca patients compared to those without CA, both in the bridged (56% vs 37%; p<0.001) and the non-bridged (48% vs 39%; p<0.05) groups. The 3 month rate for the composite of VTE, ATE or bleeding was higher among Ca patients compared to patients without Ca (5% vs 2%; p=0.004) due to higher post procedure rates of VTE (1% vs 0.2%; p<0.001) and major bleeding (4% vs 1.7%; p=0.009); the post procedure ATE rates were low in both groups (0.40% vs 0.45%). For the entire cohort, patients receiving bridging LMWH had a significantly higher rate of post procedure bleeding (5% vs 1%; p<0.05). Finally, there were significantly more deaths in Ca patients compared to non-Ca patients (5% vs. 1%; p<0.001). Conclusions: The three-month rates of VTE, major bleeding and death among patients with Ca in whom anticoagulation is temporarily interrupted for an invasive procedure is significantly higher than in patients without Ca, especially the major bleeding rate. Use of heparin increases this rate even farther, suggesting that bridging should be used with caution in patients with active cancer. Disclosures: No relevant conflicts of interest to declare.

AbstractBackgroundCancer‐associated venous thromboembolism (VTE) carries a high rate of recurrence and death. Guidelines recommend continued anticoagulation therapy as long as active cancer persists. Apixaban 2.5 mg twice daily is the FDA‐approved dose for secondary prevention regardless of VTE causation. Whether this apixaban dose is appropriate for secondary VTE prevention in cancer patients is not clear. The rationale and design of this investigator initiated phase III, multicenter, randomized, double‐blind, trial assessing apixaban 2.5 mg vs 5 mg twice daily for 12 months for the secondary VTE prevention in cancer patients (n = 370) who have completed 6 months (but no more than 12 months) of anticoagulation is provided (NCT03080883).Methods/DesignThe primary study objective is to estimate differences in the combined rate of major plus clinically relevant non‐major bleeding for apixaban 2.5 mg vs 5 mg twice daily. Secondary efficacy outcome is to assess rates of venous or arterial thromboembolism. Participating centers are chosen from the Academic and Community Cancer Research United (ACCRU) consortium.ConclusionWe anticipate these trial results to provide evidence supporting low‐dose apixaban as a safe agent for secondary prevention of cancer‐associated VTE for patients who have already completed 6‐12 months of anticoagulation.

Abstract Renal vein thrombosis (RVT), although uncommon, is associated with considerable morbidity and mortality. Neither the etiology nor the natural history of RVT has been adequately described in a large case series. Objective: To determine whether incident RVT is associated with an increased likelihood of recurrent local and systemic venous thromboembolic disease. Methods: Cases were identified by reviewing the Diagnostic Index for all patients with RVT at our institution between 1981 and 2000. Results: The study group consisted of 240 patients (34% women) with a mean age 55± 19 years. The diagnosis of RVT was made by CT (35%), Duplex Ultrasound (35%), MRI±gadolinium (10%) and either at surgery or autopsy in the remainder. The underlying etiology was deemed to be malignancy in 65% of cases. Of these, renal cell carcinoma (74%) and Wilms tumor (3%) made up the majority. Nephrotic syndrome primarily membranous glomerulonephritis was the second most common underlying etiology (23%). Of those tested, a definable thrombophilia was found in only 13 cases including lupus anticoagulant/antiphospholipid antibody (n=4); deficiencies of protein C or S, (n=2 each); heparin induced thrombocytopenia (n=2); antithrombin deficiency, dysfibrinogenemia and hyperhomocysteinemia (n=1 each). Eighty-one patients (34%) were treated with warfarin. Over a mean follow up of 3 years, the rate of recurrence of venous thrombosis at any site was 5%. The mortality rate over this time period was 49%. Conclusion: RVT represents a distinct clinical entity relative to venous thromboembolism of the lower extremity. The observed low rate of recurrence may be explained by the high mortality rate owing to a high percentage of renal malignancy. RVT should prompt an evaluation for an underlying renal malignancy.

Abstract Background Congenital/hereditary qualitative platelet disorders (CQPD) can be classified by platelet count (eg, normal or decreased) and platelet size as well as by functional defect. Based on mean platelet volume (MPV), congenital thrombocytopenias (CT) are classified as macro-thrombocytopenias (eg, Bernard-Soulier syndrome [BSS], MYH-9 [myosin heavy chain 9, non-muscle]-associated thrombocytopenias, gray platelet syndrome [GPS], etc.); microthrombocytopenias (eg, Wiskott-Aldrich syndrome and variants); and those with normal platelet size. CQPDs with normal platelet count include Glanzmann thrombasthenia (GT), dense granule storage pool disorders (DG-SPD) including Hermansky-Pudlak syndrome (HPS), platelet secretion disorders and many others. Diagnosis has relied on platelet counting and sizing, blood smear light microscopy, platelet aggregation (agg) and platelet function analyzer (PFA-100) studies. Platelet transmission electron microscopy (PTEM) and flow cytometry can provide supplementary information and molecular analysis is also evolving. The objective of this study was to determine the roles of platelet transmission electron microscopy (PTEM) and flow cytometry in the diagnosis of CQPD and CT. Methods In this retrospective cohort study, after IRB approval, the electronic medical record system was queried for patients (pt) with a confirmed CQPD or CT seen at Mayo Clinic between 2000 and 2015. A detailed chart review was undertaken. Results 54 pt (64% female) met our study criteria; median age was 32 years (range 1 day to 81 years). 18/54 (33%) pt had macrothrombocytopenia: BSS 4 (7%); MYH-9 10 (19%); gray platelet syndrome 4 (7%). 36/54 (66%) had normal MPV: Glanzmann thrombasthenia 6 (11%); storage pool disorders including DG-SPD 10 (19%) and HPS 2 (3%), mild alpha granule deficiency 3 (6%) and York platelet syndrome 4 (7%); platelet secretion disorders 4 (7%); ANKRD26 mutation 3 (6%); congenital amegakaryocytic thrombocytopenia 1 (2%); GATA-1 mutation 1 (2%); RUNX-1 mutation 1 (2%); and Jacobsen syndrome 1 (2%). 44 pt (81%) had a positive bleeding history: epistaxis 52%, cutaneous bleeding 57%, gastrointestinal bleeding 21% and menorrhagia 54%; 10 pt (19%) had a negative bleeding history. Results of standard and esoteric platelet testing are summarized in Table 1. Diagnosis in the 10 pt with glycoprotein deficiency (BSS or GT) was established by agg; flow cytometry was confirmatory but not necessary. Of the 23 pt with SPD, 5 had a negative bleeding history; 4 pt had normal agg and PFA-100 and were diagnosed exclusively by PTEM. In this group, the abnormalities on platelet aggregation and PFA were variable and PTEM allowed for a better definition of the specific abnormalities. For MYH-9 patients, PTEM confirmed leukocyte inclusions that had already been identified on light microscopy. PTEM was the only diagnostic modality able to identify the abnormality in York platelet syndrome. In 5/54 (9%) genetic testing was necessary for diagnosis (GATA-1, ANKRD26 and RUNX-1) Conclusion In this cohort, standard platelet assays established the diagnosis in the large majority of CQPD and CT. PTEM was essential for confirmation in DG-SPD, mild alpha granule deficiency and York platelet syndrome and useful in combination with molecular testing to establish a diagnosis in selected cases. Guidance on selection of patients for such specialized testing requires further study. Table 1. Results of standard and esoteric platelet testing for 54 patients with congenital qualitative platelet disorders and/or thrombocytopenia Disorder n (%) Platelet aggregation PFA PTEM Flow cytometry Confirmation by genetics Done Abnormal Done Abnormal Done Abnormal Done Abnormal Glanzmann thrombasthenia 6 (11) 6 6 5 5 1 0 3 3 0 Bernard-Soulier syndrome & variants 4 (7) 4 4 4 4 3 0 4 4 0 MYH-9 related disorders 10 (19) 7 2 8 3 5 5 4 2 5 Dense granule deficiency and HPS 12 (22) 12 8 12 8 12 12 4 0 0 Alpha granule deficiency* 7 (13) 7 4 7 6 7 7 4 4 1 York platelet syndrome 4 (7) 1 0 1 1 4 4 1 1 0 TXA2 or PG synthesis/receptor defect 4 (7) 4 4 4 3 3 0 3 0 0 CATM 1 (2) 0 - 0 - 0 - 0 - 1 ANKRD26 3 (6) 3 3 3 2 3 3 3 3 3 GATA-1 1 (2) 0 - 1 1 1 1 1 1 1 RUNX-1 1 (2) 1 0 1 1 0 - 0 - 1 Jacobsen syndrome 1 (2) 1 0 1 1 1 1 1 0 1 MYH-9: myosin heavy chain 9, non-muscle (MHY-9) associated thrombocytopenia, HPS: Hermansky-Pudlak Syndrome, TXA2: thromboxane A2, PG: prostaglandin CATM: congenital amegakaryocytic thrombocytopenia. * Includes gray platelet syndrome Disclosures Pardanani: Stemline: Research Funding.

Abstract Background: While Factor V Leiden is associated with an increased risk of thrombosis, the magnitude of that risk among homozygous carriers is uncertain. Methods: In a cross-sectional study of Mayo Clinic patients referred to the Special Coagulation Laboratory for a thrombophilia profile (n=379) over the 18-year period, 1996-2013, the prevalence of venous and arterial thrombosis was estimated for patients found to be Factor V Leiden carriers based on leukocyte genomic DNA genotyping. T tests and chi-square tests were used for continuous and categorical variables, respectively. Results: Among homozygous (n=111) and heterozygous (n=268) carriers, the mean age at testing (50.3 and 50.5 years, respectively; p=0.9) and the proportion of females (50% and 54%, respectively; p=0.5) did not differ significantly. Of 29 asymptomatic carriers at the time of testing, 14 were homozygotes. Of the remaining 350 carriers, the mean age at first venous or arterial thrombosis (42 vs 43.8 years; p=0.5) among homozygous and heterozygous carriers, respectively, did not differ significantly. Thirty-five (33%) and 83 (31%) homozygous and heterozygous carriers, respectively, had at least one recurrent venous or arterial thrombosis (p=0.72). The prevalence of deep venous thrombosis (DVT) was 61% and 46% in homozygous and heterozygous carriers, respectively (p=0.008); the prevalence of pulmonary embolism was 18% and 20%, respectively (p=0.69). The prevalence of arterial thrombosis (mainly stroke and/or TIA) was higher in heterozygous (23%) compared to homozygous carriers (8%). Conclusion: In the largest sample of homozygous Factor V Leiden carriers reported to date, thrombosis penetrance and phenotype did not appear to differ among homozygous vs. heterozygous carriers with the exception of a higher prevalence of DVT among homozygous carriers. These data should be interpreted with caution due to the potential for referral bias. Disclosures No relevant conflicts of interest to declare.

Abstract Background: Patients on systemic therapy for cancer are at varying risk for venous thromboembolism (VTE) and its consequences. Thromboprophylaxis is recommended in hospitalized medical and surgical cancer patients, but most VTE occurs in ambulatory cancer patients where risk can be estimated with a validated score. However, the benefit of extended outpatient thromboprophylaxis is uncertain with heparins and has not been tested with direct oral anticoagulants. Methods: We conducted a double-blind, randomized, placebo-controlled, parallel-group, multicenter study in adult ambulatory patients with various cancers initiating a new systemic regimen and at increased risk for VTE (defined as Khorana score ≥ 2). Enrolled subjects were screened for deep-vein thrombosis (DVT) and if none found randomized 1:1 to rivaroxaban 10 mg once daily or placebo up to day 180. Subjects were screened with lower extremity ultrasounds every 8 weeks on study. Primary efficacy endpoint was a composite of objectively confirmed symptomatic or asymptomatic lower-extremity proximal DVT, symptomatic upper- or lower-extremity distal DVT, symptomatic or incidental pulmonary embolism and VTE-related death. ISTH-defined major bleeding was the primary safety endpoint. All endpoints were adjudicated by blinded independent committees. Analyses for efficacy endpoints were conducted for intent-to-treat (ITT) population (all randomized patients) for the up-to-day 180 observation period (primary) and the on-treatment period (supportive). Safety analyses were conducted for on-treatment period only for patients who received at least one dose of study drug. Results: Of 1,080 patients who provided consent, 49 (4.53%) had DVT on baseline screening and another 190 screen-failed due to other reasons. Of 841 randomized patients, 274 (32.6%) had pancreatic cancer; 698 (83%) were white and 428 (50.9%) were male. The primary efficacy endpoint occurred in 25 of 420 patients (5.95%) and 37 of 421 patients (8.79%) (HR, 0.66; 95% CI, 0.40 to 1.09; p=0.101) in the rivaroxaban and placebo groups respectively (number needed to treat, NNT=35) in the up-to-day 180 observation period (Figure 1A). Of all patients with VTE, 38.70% experienced events after discontinuing study drug. In a pre-specified analysis of all randomized patients during the on-treatment period, the primary endpoint occurred in 11 of 420 patients (2.62%) and 27 of 421 (6.41%) in rivaroxaban and placebo groups respectively (HR 0.40, 95% CI 0.20 to 0.80, p=0.007) (NNT=26) (Figure 1B). Major bleeding occurred in 8 of 405 (1.98%) in the rivaroxaban group and in 4 of 404 (0.99%) patients in the placebo group (hazard ratio, 1.96; 95% CI, 0.59 to 6.49; p=0.265) (number needed to harm, NNH=101). Clinically relevant non-major bleeding occurred in 2.72% and 1.98% of rivaroxaban and placebo groups, respectively (HR, 1.34; 95% CI, 0.54 to 3.32; p=0.53) (NNH=135). Adverse events were comparable between groups. For secondary efficacy endpoints, a pre-specified analysis of the composite of primary endpoint with addition of arterial and visceral thromboembolic events in the up-to-day 180 observation period showed significantly fewer events in rivaroxaban versus placebo group (6.90% versus 10.70% respectively; HR, 0.62; 95% CI: 0.39, 0.99; p=0.04). All-cause mortality occurred in 20.0% of patients in rivaroxaban group and 23.8% in placebo group (HR=0.83, 95% CI 0.62, 1.11; p=0.213). A pre-specified composite of the primary endpoint with all-cause mortality occurred in 23.1% of patients in rivaroxaban group and 29.5% in placebo group (HR 0.75; 95% CI 0.57 to 0.97; p=0.03) (Figure 1C). Conclusions: Rivaroxaban significantly reduced VTE and VTE-related death during the on-treatment period but not during the full study period; over one-third of events occurred post discontinuation of study drug. The incidence of major bleeding was low. The Khorana risk score cut-off of ≥2 identified cancer patients at high risk of thrombotic events both at baseline (4.53%) and during study (8.79% with additional 1.66% arterial events in placebo group). These results should inform future recommendations regarding thromboprophylaxis in at-risk ambulatory cancer patients. (Funded by Janssen; ClinicalTrials.gov number, NCT02555878) Figure 1 Figure 1. Disclosures Khorana: Parexel: Other: Personal fees and non-financial support for travel; Sanofi: Consultancy, Other: Personal fees and non-financial support for travel; Pfizer: Consultancy, Other: Personal fees and non-financial support for travel; Janssen: Consultancy, Other: Personal fees, Research Funding; TriSalus: Other: Personal fees; Halozyme: Other: Personal fees and non-financial support for travel; Seattle Genetics: Other: Personal fees and non-financial support for travel; AngioDynamics: Other: Personal fees and non-financial support for travel; LEO Pharma: Other: Personal fees and non-financial support for travel; Medscape/WebMD: Other: Personal fees and non-financial support for travel; Pharmacyclics: Other: Personal fees; PharmaCyte: Other: Personal fees; Bayer: Consultancy, Other: Personal fees and non-financial support for travel. Soff:Janssen: Research Funding; Amgen: Research Funding. Kakkar:Bayer AG: Consultancy, Research Funding; Boehringer Ingelheim: Consultancy; Daiichi Sankyo Europe: Consultancy; Janssen Pharmaceuticals: Consultancy; Pfizer: Consultancy; Sanofi S.A.: Consultancy; Verseon: Consultancy. Vadhan-Raj:AMAG Pharmaceuticals, Inc: Other: received funding from Amag to support clinical trial; Janssen: Consultancy, Research Funding. Riess:Janssen Scientific Affairs: Other: Travel reimbursement; Bayer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Boehringer Ingelheim: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees. Wun:Eli Lilly, Inc.: Research Funding; Emmaus, Inc.: Membership on an entity's Board of Directors or advisory committees; Glycomimetics, Inc.: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Pfizer, Inc.: Membership on an entity's Board of Directors or advisory committees. Streiff:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; CSL Behring: Other: outcome adjudication committee; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Boehringer Ingelheim: Research Funding; Roche: Research Funding; Portola: Consultancy, Research Funding. Garcia:Shingoi: Consultancy; Portola: Research Funding; Pfizer: Consultancy; Janssen: Consultancy, Research Funding; Incyte: Research Funding; Daiichi Sankyo: Research Funding; Bristol Meyers Squibb: Consultancy; Boehringer Ingelheim: Consultancy; Retham Technologies LLC: Consultancy; Genzyme Corporation: Consultancy; Alexion: Consultancy. Liebman:Janssen (Johnson & Johnson): Other: steering committee of the CASSINI trial during the conduct of the study. Belani:Janssen: Consultancy. O'Reilly:3DMed, Agios, AlignMed, Amgen, Antengene, Aptus, ASLAN, Astellas, AstraZeneca, Bayer, BeiGene, Bioline, BMS, Boston Scientific, Bridgebio, CARsgen, Celgene, CASI, Cipla, CytomX, Daiichi, Debio, Delcath, Eisai, Exelixis, Genoscience, Gilead, Halozyme: Consultancy; Hengrui, Incyte, Inovio, Ipsen, Jazz, Janssen, Kyowa Kirin, LAM, Lilly, Loxo, Merck, Mina, NewLink Genetics, Novella, Onxeo, PCI Biotech, Pfizer, PharmaCyte, Pharmacyclics, Pieris, QED, RedHill, Sanofi, Servier, Silenseed, Sillajen, Sobi, Targovax: Consultancy; Janssen: Research Funding; Acta Biologica, Agios, Array, AstraZeneca, Bayer, BeiGene, BMS, CASI, Celgene, Exelixis, Genentech, Halozyme, Incyte, Lilly, MabVax, Novartis, OncoQuest, Polaris Puma, QED, and Roche: Research Funding; Tekmira, twoXAR, Vicus, Yakult, and Yiviva: Consultancy. Patel:Janssen Pharmaceuticals: Research Funding. Yimer:Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Speakers Bureau; AstraZeneca: Speakers Bureau; Epizyme: Equity Ownership; Clovis Oncology: Equity Ownership; Puma Biotechnology: Equity Ownership. Wildgoose:Janssen Scientific Affairs: Employment; Johnson & Johnson: Equity Ownership. Burton:Janssen Pharmaceuticals: Employment; Johnson & Johnson: Equity Ownership. Vijapurkar:Janssen Pharmaceuticals, Inc.: Employment; Johnson & Johnson: Equity Ownership. Kaul:Janssen Pharmaceuticals, Inc.: Employment; Johnson & Johnson: Equity Ownership. Eikelboom:AstraZeneca, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb/Pfizer, Daiichi Sankyo, GlaxoSmithKline, Janssen, sanofi-aventis, and Eli Lilly: Honoraria, Research Funding; Heart and Stroke Foundation: Other: Personnel award. Bauer:Janssen: Consultancy. Kuderer:Celldex: Consultancy; Mylan: Consultancy, Other: Travel, Accommodations, Expenses; Myriad Genetics: Consultancy; Halozyme: Consultancy; Coherus Biosciences: Consultancy, Other: Travel, Accommodations, Expenses; Janssen Scientific Affairs, LLC: Consultancy, Other: Travel, Accommodations, Expenses; Pfizer: Consultancy; Bayer: Consultancy. Lyman:Halozyme; G1 Therapeutics; Coherus Biosciences: Consultancy; Generex Biotechnology: Membership on an entity's Board of Directors or advisory committees; Amgen: Other: Research support.