García, David

Abstract Systems-based hematology (SBH) is an emerging discipline focused on optimizing care delivery for patients with hematologic disorders within complex health care systems. Despite its growing importance, the field lacks a formal definition, standardized curriculum, and clear career pathway, hindering widespread adoption and training of future SBH experts. We sought to define core principles, competencies, challenges, and future directions of SBH to identify foundational components for a potential educational curriculum. Semistructured interviews were conducted with 8 SBH experts. Expert participants were identified through their committee involvement with the American Society of Hematology. Five overarching themes emerged: (1) The accidental expert: SBH careers have developed organically and reactively in response to pressing institutional needs, not through formal training; (2) Defining the unseen: experts define the field pragmatically by its function and roles; (3) The SBH toolkit: success requires a hybrid skillset combining clinical hematology expertise with health systems science (HSS) principles; (4) The architect's dilemma: the field's growth is hindered by interdependent challenges of building a curriculum, awareness, and securing resources; and (5) Charting the future: the discipline is poised for growth, driven by increasing health care complexity and specialization. SBH represents the nexus of HSS principles and hematology care. Formalizing SBH requires a multipronged approach, including developing a standardized curriculum that equips learners with a hybrid skillset, creating clear value for health systems and patients, and fostering a community of practice through professional societies. These findings provide a foundational framework for developing educational resources and institutional support necessary to continue advancing SBH.

Introduction: Systems-based hematology (SBH) is an emerging field focused on improving hematology care delivery through quality improvement (QI) and health systems science (HSS). However, a universal definition and standardized training curriculum are lacking. This study aimed to explore experts' perspectives on defining SBH, identify core knowledge and skills, and discuss challenges and opportunities in developing a curriculum. Methods: Semi-structured interviews were conducted with eight hematologists who have expertise in SBH through practical experience, scientific publications, and serve on related committees for the American Society of Hematology. These interviews were automatically transcribed through Microsoft Teams. Thematic analysis, using both inductive and deductive coding, was employed to identify themes and subthemes from the verbatim interview transcripts. This was accomplished with a large language model (LLM; Google Gemini Advanced, June 2024). Results: In combination, these semi-structured interviews lasted approximately 400 minutes and generated 231 pages of transcript text with 63117 words for analysis. Five main themes and associated subthemes were identified. (1) Defining SBH: experts highlighted the lack of a universal definition for SBH, emphasizing the reason it is often defined by its functions, such as improving healthcare delivery, ensuring appropriate use of resources, and addressing disparities in care. They often compared SBH to other fields like antimicrobial stewardship or implementation science to illustrate its expansive role and scope. (2) The Role and Scope of SBH: experts described SBH as encompassing a broad range of activities, including improving healthcare delivery, implementing QI initiatives, conducting pragmatic research, and advocating for policy changes at various levels. They emphasized the importance of data-driven approaches and collaboration with other healthcare professionals. (3) Training and Education in SBH: the lack of formal training programs and curricula for SBH was a recurring theme. Experts suggested that a comprehensive curriculum should include QI methodologies, implementation science, clinical informatics, health economics, leadership skills, and hematology-specific examples and case studies. They proposed various delivery methods, including asynchronous online modules, virtual workshops, and in-person sessions, targeting hematology fellows, junior faculty, and other healthcare professionals involved in hematology care. They unanimously agreed that a SBH curriculum could borrow heavily from an established HSS curriculum but should incorporate hematology-specific examples. (4) Challenges and Barriers to Implementing SBH: experts identified several challenges, including the lack of awareness and recognition of SBH among healthcare professionals and administrators, resource constraints, and the need for institutional buy-in. They also highlighted the technical difficulty of measuring and demonstrating the value of SBH interventions, particularly in terms of cost savings and improved patient outcomes. (5) The Future of SBH: despite the challenges, experts expressed optimism about the future of SBH, predicting its growing importance and expanding scope, including malignant hematology, community practice, and pediatrics. They envisioned SBH playing a crucial role in addressing rising healthcare costs, quality concerns, and disparities in care. They also anticipated the integration of new technologies like artificial intelligence, “virtual” care delivery, and molecular genetics into SBH practice. Conclusions: This study provides valuable insights into the current state of SBH and the need for a standardized curriculum. The findings can inform the development of educational resources and training programs to equip future practitioners with the necessary knowledge and skills to effectively practice SBH and improve hematology care delivery. This study also sheds light on the utility of qualitative research within SBH and the emerging analytical tools that will require further exploration and standardization (e.g., LLM prompt engineering).

Objective To develop new antiphospholipid syndrome (APS) classification criteria with high specificity for use in observational studies and trials, jointly supported by the American College of Rheumatology (ACR) and EULAR. Methods This international multidisciplinary initiative included 4 phases: 1) Phase I, criteria generation by surveys and literature review; 2) Phase II, criteria reduction by modified Delphi and nominal group technique exercises; 3) Phase III, criteria definition, further reduction with the guidance of real‐world patient scenarios, and weighting via consensus‐based multicriteria decision analysis, and threshold identification; and 4) Phase IV, validation using independent adjudicators’ consensus as the gold standard. Results The 2023 ACR/EULAR APS classification criteria include an entry criterion of at least one positive antiphospholipid antibody (aPL) test within 3 years of identification of an aPL‐associated clinical criterion, followed by additive weighted criteria (score range 1–7 points each) clustered into 6 clinical domains (macrovascular venous thromboembolism, macrovascular arterial thrombosis, microvascular, obstetric, cardiac valve, and hematologic) and 2 laboratory domains (lupus anticoagulant functional coagulation assays, and solid‐phase enzyme‐linked immunosorbent assays for IgG/IgM anticardiolipin and/or IgG/IgM anti–β 2 ‐glycoprotein I antibodies). Patients accumulating at least 3 points each from the clinical and laboratory domains are classified as having APS. In the validation cohort, the new APS criteria versus the 2006 revised Sapporo classification criteria had a specificity of 99% versu s 86%, and a sensitivity of 84% versus 99%. Conclusion These new ACR/EULAR APS classification criteria were developed using rigorous methodology with multidisciplinary international input. Hierarchically clustered, weighted, and risk‐stratified criteria reflect the current thinking about APS, providing high specificity and a strong foundation for future APS research.

Abstract Background: Guidelines suggest the use of the Khorana score to select patients with solid cancer receiving chemotherapy for thromboprophylaxis to prevent venous thromboembolism (VTE), but its performance in different types of cancers remains uncertain. Methods: The present analysis includes individual patient data from seven randomized controlled trials that had compared prophylactic (ultra)-low-molecular-weight heparin (LMWH) with placebo or observation in patients with solid cancer. The analysis addresses the performance of the continuous and dichotomized Khorana score in predicting the 6-month risk of VTE in the trial control groups, overall and in types of cancer studies, as well as the efficacy and safety of LMWH among patients with a high-risk Khorana score. Random effects meta-analysis provided the basis for summary estimates. Findings: In the 3,403 patients from the control groups included in the analyses, the mean age was 61 years, 59% were male, and 58% had lung cancer. During 6-months of follow-up, 188 patients (5.5%) developed VTE. Overall, the 6-month VTE incidence was 9.8% among high-risk Khorana score patients and 6.4% among low-to-intermediate risk patients (OR 1.6; 95%-CI 1.1-2.2). The dichotomous Khorana score performed differently in lung cancer patients (OR 1.1; 95%-CI, 0.72-1.7) than in those with other types of cancer (OR 4.4; 95%-CI, 2.7-7.3; P interaction=0.002). Among high-risk patients, LMWH decreased the risk of VTE by 64% compared to placebo or observation (OR 0.36; 95%-CI, 0.22-0.58). In the group of patients with types of cancer other than lung cancer and a high-risk Khorana score (N=619), the 6-month VTE incidence was 3.3% (95% CI, 1.4 to 7.7) among LMWH recipients and 13% (95% CI, 6.8 to 24) among those not receiving LMWH (OR 0.23, 95% CI, 0.11 to 0.46; P <0.001). There was no difference in major bleeding (OR 1.2, 95% CI, 0.56 to 2.5). Interpretation: The Khorana score performs poorly in differentiating between those at high and low risk of VTE in patients with lung cancer, but is associated with a 4-fold increased risk of VTE in those with other types of cancer. Thromboprophylaxis is effective and safe in patients with a high-risk Khorana score. Funding: Canadian Institutes of Health Research knowledge synthesis grant, KRS 126594 Registration: International Prospective Register for Systematic Reviews (PROSPERO), CRD42013003526. Disclosures Van Es: Pfizer: Employment, Other: Comment: Dr. van Es reports personal fees from Pfizer as a member of their advisory board. These fees are unrelated to this project.. Crowther: Alexion: Speakers Bureau; Bayer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Boehringer Ingelheim: Speakers Bureau; Leo Pharma: Research Funding; Pfizer: Honoraria; Portola: Consultancy; Shinogi: Consultancy. Macbeth: Cancer Research UK: Research Funding; Pfizer: Other: Provision of Dalteparin for FRAGMATIC trial. Griffiths: Pfizer: Consultancy, Other: Comment: I run an academic clinical trials unit, have received educational/investigator intiated research grants from companies that make these heparin agents. As consultant > 3 years ago, advised Pfizer on clinical trial designs unrelated to this study., Research Funding. Streiff: Roche: Research Funding; Portola: Research Funding; Janssen Scientific Affairs, LLC: Consultancy, Research Funding; CSL Behring: Consultancy, Research Funding. Ageno: Daiichi Sankyo: Consultancy, Honoraria; Bayer AG: Consultancy, Honoraria, Research Funding; BMS-Pfizer: Consultancy, Honoraria; Boehringer Ingelheim: Consultancy, Honoraria. Bozas: PharmaMar: Honoraria. Maraveyas: Bayer: Other: Personal fees and conference attendance; Bristol-Myers Squibb: Other: Grants and personal fees; Leo Pharma: Other: Grants, personal fees and conference attendance; Pfizer: Other: Personal fees. Loprinzi: Bristol Myers: Other: Grant - unrelated to this project; Janssen: Other: Grant - unrelated to this project. McBane: Bristol Myers Squibb: Other: Research grant for cancer associated VTE. Schünemann: Canadian Institutes of Health Research: Research Funding.

Abstract Background: Parenteral anticoagulants may improve outcomes in patients with cancer by reducing the risk of venous thromboembolism (VTE) and through a direct anti-tumour effect. Study-level meta-analysis indicates a reduction in VTE and provide moderate certainty that a small survival benefit exists; it is unclear if patients with specific cancers benefit more or less. Utilizing data from randomized controlled trials (RCT), this individual participant data meta-analysis examines the impact of heparin on survival, VTE and major bleeding in oncological patients randomized to low-molecular weight heparin (LMWH) or no LMWH. Methods: We performed a comprehensive systematic search for all RCTS (last search date March 2017) and contacted authors and sponsors to obtain individual participant data of patients with solid cancers and no other indication for prophylactic or therapeutic anticoagulation. We utilized the GRADE approach to evaluate the certainty of evidence and produce an evidence profile. All analyses followed the intention-to-treat principle. We calculated the impact on mortality through multivariable hierarchical models with patient-level variables as fixed effects and a categorical trial variable as a random effect. We adjusted the analysis for age, cancer type and metastasis status. To investigate whether intervention effects vary by predefined subgroups, including type of cancer, we tested interaction terms in the statistical model. Results: A total of 18 RCTs (n=10,041 participants) were eligible for inclusion and we obtained data from 82.4% of the participants (13 RCTs, n=8,278; n=4,139 for LMWH and n=4,139 for no LMWH). The meta-analysis revealed an adjusted relative risk of mortality within one year of 0.99 (95% CI: 0.95, 1.03) and a hazard ratio of 0.97 (95% CI: 0.82, 1.14) after one year. The relative risk for VTE was 0.58 (95% CI: 0.48, 0.71), 0.57 (95% CI: 0.44, 0.74) for symptomatic deep vein thrombosis and 0.58 (95%CI: 0.44, 0.77) for symptomatic pulmonary embolism, separately. For every 1,000 patients treated, approximately 16 fewer would experience symptomatic DVT and 16 fewer would experience any PE. The adjusted relative risk for major bleeding throughout trial duration was 1.24 (95% CI: 0.91, 1.69; P=0.17). Subgroup analysis, by cancer type, of VTE occurrence throughout trial duration identified lung cancer OR=0.52 (95% CI: 0.39, 0.68; P<0.001) and pancreatic cancer OR=0.55 (95% CI: 0.35, 0.88; P=0.01) patients as experiencing the greatest benefit from LMWH treatment. The certainty of the evidence for the outcomes was moderate to high. Conclusion: LMWH reduces risk of VTE without increasing risk of bleeding but does not improve survival across all patients. Funding: Canadian Institutes of Health Research knowledge synthesis grant, KRS 126594 Registration: International Prospective Register for Systematic Reviews (PROSPERO), CRD42013003526. Disclosures Schünemann: Canadian Institutes of Health Research: Research Funding. Crowther: Alexion: Speakers Bureau; Bayer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Boehringer Ingelheim: Speakers Bureau; Leo Pharma: Research Funding; Pfizer: Honoraria; Portola: Consultancy; Shinogi: Consultancy. Macbeth: Pfizer: Other: Provision of Dalteparin for FRAGMATIC trial; Cancer Research UK: Research Funding. Griffiths: Pfizer: Consultancy, Other: Comment: I run an academic clinical trials unit, have received educational/investigator intiated research grants from companies that make these heparin agents. As consultant > 3 years ago, advised Pfizer on clinical trial designs unrelated to this study., Research Funding. Van Es: Pfizer: Employment, Other: Comment: Dr. van Es reports personal fees from Pfizer as a member of their advisory board. These fees are unrelated to this project.. Streiff: Roche: Research Funding; Portola: Research Funding; Janssen Scientific Affairs, LLC: Consultancy, Research Funding; CSL Behring: Consultancy, Research Funding. Ageno: BMS-Pfizer: Consultancy, Honoraria; Bayer AG: Consultancy, Honoraria, Research Funding; Boehringer Ingelheim: Consultancy, Honoraria; Daiichi Sankyo: Consultancy, Honoraria. Bozas: PharmaMar: Honoraria. McBane: Bristol Myers Squibb: Other: Research grant for cancer associated VTE. Maraveyas: Bayer: Other: Personal fees and conference attendance; Bristol-Myers Squibb: Other: Grants and personal fees; Leo Pharma: Other: Grants, personal fees and conference attendance; Pfizer: Other: Personal fees. Loprinzi: Bristol Myers: Other: Grant - unrelated to this project; Janssen: Other: Grant - unrelated to this project.

Abstract Heparin-induced thrombocytopenia (HIT) is a life-threatening, prothrombotic, antibody-mediated disorder. To maximize the likelihood of recovery, early and accurate diagnosis is critical. Widely available HIT assays, such as the platelet factor 4 (PF4) heparin enzyme-linked immunosorbent assay (ELISA) lack specificity, and the gold-standard carbon 14–labeled serotonin release assay (SRA) is of limited value for early patient management because it is available only through reference laboratories. Recent studies have demonstrated that pathogenic HIT antibodies selectively activate PF4-treated platelets and that a technically simpler assay, the PF4-dependent P-selectin expression assay (PEA), may provide an option for rapid and conclusive results. Based upon predefined criteria that combined 4Ts scores and HIT ELISA results, 409 consecutive adults suspected of having HIT were classified as disease positive, negative, or indeterminate. Patients deemed HIT indeterminate were considered disease negative in the primary analysis and disease positive in a sensitivity analysis. The ability of PEA and SRA to identify patients judged to have HIT was compared using receiver operating characteristic curve statistics. Using these predefined criteria, the diagnostic accuracy of PEA was high (area under the curve [AUC], 0.94; 95% confidence interval [CI], 0.87-1.0) and similar to that of SRA (AUC, 0.91; 95% CI, 0.82-1.0). In sensitivity analysis, the AUCs of PEA and SRA were also similar at 0.88 (95% CI, 0.78-0.98) and 0.86 (95% CI, 0.77-0.96), respectively. The PEA, a technically simple nonradioactive assay that uses ∼20-fold fewer platelets compared with the SRA, had high accuracy for diagnosing HIT. Widespread use of the PEA may facilitate timely and more effective management of patients with suspected HIT.

Background: The use of nonsteroidal anti-inflammatory drugs (NSAIDs) with oral anticoagulants has been associated with an increased risk of bleeding. We investigated the risk of bleeding and major cardiovascular outcomes in patients with atrial fibrillation taking NSAIDs and apixaban or warfarin. Methods: The ARISTOTLE trial (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation; n=18 201) compared apixaban with warfarin in patients with atrial fibrillation at an increased risk of stroke. Patients in ARISTOTLE without severe renal (creatine clearance ≤30 mL/min) or liver disease were included in this analysis (n=17 423). NSAID use at baseline, NSAID use during the trial (incident NSAID use), and never users were described. The primary outcome was major bleeding. Secondary outcomes included clinically relevant nonmajor bleeding, gastrointestinal bleeding, heart failure hospitalization, stroke or systemic embolism, and all-cause mortality. NSAID use during the trial, and the interaction between randomized treatment, was analyzed using time-dependent Cox proportional hazards models. Results: Those with baseline NSAID use (n=832 [4.8%]), incident NSAID use (n=2185 [13.2%]), and never users were similar in median age (age [25th, 75th]; 70 [64, 77] versus 70 [63, 75] versus 70 [62, 76]). Those with NSAID use at baseline and incident NSAID use were more likely to have a history of bleeding than never users (24.5% versus 21.0% versus 15.6%, respectively). During a median follow-up (25th, 75th) of 1.8 (1.4, 2.3) years and when excluding those taking NSAID at baseline, we found that incident NSAID use was associated with an increased risk of major bleeding (hazard ratio [HR], 1.61 [95% CI, 1.11–2.33]) and clinically relevant nonmajor bleeding (HR, 1.70 [95% CI, 1.16–2.48]), but not gastrointestinal bleeding. No significant interaction was observed between NSAID use and randomized treatment for any outcome. Conclusions: A substantial number of patients in the ARISTOTLE trial took NSAIDs. Incident NSAID use was associated with major and clinically relevant nonmajor bleeding, but not with gastrointestinal bleeding. The safety and efficacy of apixaban versus warfarin appeared not significantly to be altered by NSAID use. This study warrants more investigation of the effect of NSAIDs on the outcomes of patients treated with apixaban. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT00412984.

Abstract Introduction: Heparin-induced Thrombocytopenia (HIT) is a potentially life and limb threatening pro-thrombotic syndrome triggered by antibodies to platelet factor 4 (PF4)/polyanion complexes. Commonly used screening tests such as the PF4/Heparin ELISA (PF4 ELISA), while easy to perform in the near-patient setting, are highly non-specific. In contrast, more accurate tests such as the serotonin release assay (SRA) are technically complex, require radioactivity and are performed in only a handful of reference laboratories. These diagnostic challenges lead to both unnecessary anticoagulant use as well as avoidable cases of severe bleeding. Recent reports suggest that a relatively simple three-hour flow cytometry-based test that uses PF4-treated normal platelets, the PEA (PF4-dependent p-selectin Expression Assay), is at least as accurate as the SRA for identifying patients who have HIT (Thromb Haemost. 2015 Nov 25;114(6):1322-3; Chest. 2016 Sep;150(3):506-15; Chest. 2017 Oct;152(4):e77-e80). Here we describe results of a large prospective study designed to compare the accuracy of the SRA and PEA for HIT diagnosis in a clinical setting. Methods: The PEA and SRA were performed on serum samples obtained from adult patients (≥18 yrs.) from 2 large tertiary care academic hospitals from May 2016 to Sep 2017. All inpatients for whom PF4 ELISA testing was ordered were included in the study. The PEA was performed with platelets pretreated with PF4 at 3 concentrations: 30mcg/mL (PEA30), 10mcg/mL (PEA10) and 3mcg/mL (PEA3). Sera were batch-tested in both assays (SRA and PEA) using the same target platelets. The central laboratory was blinded to clinical history and to the results of the PF4 ELISA performed by participating hospitals at the time of diagnosis. Both centers performed IgG-specific PF4 ELISAs and utilized manufacturer-recommended cut-offs for positivity. Predefined "more-stringent" and "less stringent" criteria based on clinical findings (4Ts score) and results of PF4 ELISA testing were used to define the likelihood of a patient having HIT (Table 1A). Receiver Operating Curve (ROC) analysis was performed and Area Under the Curve (AUC) of each assay was calculated to assess their diagnostic accuracy. Since high test specificity was desired, positive cut-offs that maximized the sum of sensitivity and specificity in a specificity range of ≥90% and ≥95% were derived. To evaluate non-inferiority of the PEA to the SRA, we assessed whether the lower limit of the one-sided 95% confidence interval of the ΔAUC (PEA-SRA) was higher than a non-inferiority margin of 5% and 10%. Results: A total of 440 patient samples were tested with both assays. Seventeen and 28 patients were classified as having true HIT based on the use of the more- and less-stringent criteria, respectively. When classified by more-stringent criteria, the AUC was numerically greater for each of the three PEA tests than for the SRA (Table 1B). All tests had excellent accuracy (AUC>0.90, "excellent" by the Traditional academic point system). Using less-stringent criteria, the PEA30 had the highest AUC estimate followed by the SRA (Table 1C). Positive cut-offs generated at test specificities of ≥90% and ≥95% using data classified by more stringent criteria are shown in Table 1D. PEA3 was non-inferior to the SRA at a 5% non-inferiority margin, and all PEA tests were non-inferior at the 10% margin using the more stringent classification for true HIT (Fig 1A). In the less-stringently classified data set, the PEA30 was non-inferior to the SRA at a 10% margin (Fig 1B). Conclusions: The PEA, a 3-hour, non-radioactive functional HIT assay demonstrated high diagnostic accuracy and was non-inferior to the SRA using commonly accepted non-inferiority margins for diagnostic testing (5-10%). The technical advantages of the PEA over the SRA may encourage its widespread adoption as a rapid-turnaround, accurate and near-patient diagnostic for patients with suspected HIT. Disclosures Jones: BloodCenter of Wisconsin: Patents & Royalties. Curtis:Ionis Pharmaceuticals: Consultancy. Bougie:BloodCenter of Wisconsin: Patents & Royalties. Aster:BloodCenter of Wisconsin: Patents & Royalties. Garcia:Shingoi: Consultancy; Retham Technologies LLC: Consultancy; Incyte: Research Funding; Daiichi Sankyo: Research Funding; Bristol Meyers Squibb: Consultancy; Portola: Research Funding; Janssen: Consultancy, Research Funding; Pfizer: Consultancy; Boehringer Ingelheim: Consultancy. Padmanabhan:BloodCenter of Wisconsin: Patents & Royalties: Patent/royalties for HIT diagnostic testing; Veralox Therapeutics: Other: Advisory Board; Retham Technologies LLC: Equity Ownership, Other: Retham seeks to develop HITDx(TM), a new assay for HIT diagnosis; TerumoBCT: Consultancy; GE Healthcare: Other: Material support for Clinical Quality Improvement Initiative; Janssen Pharmaceuticals: Consultancy.

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.