Streiff, Michael B.

The NCCN Guidelines for Cancer-Associated Venous Thromboembolic Disease provide strategies for the prevention, diagnosis, and treatment of venous thromboembolism (VTE) in adult patients with cancer. VTE is a common and life-threatening condition in patients with cancer, and its management often requires multidisciplinary efforts. The NCCN panel is comprised of specialists spanning various fields, including cardiology, hematology, medical oncology, internal medicine, interventional radiology, and pharmacology. The content featured in this issue specifically addresses the evaluation and recommended treatment options outlined in the NCCN Guidelines for the diverse subtypes of cancer-associated VTE.

Study Design. Delphi method. Objective. To gain consensus on the following questions: (1) When should anticoagulation/antiplatelet (AC/AP) medication be stopped before elective spine surgery?; (2) When should AC/AP medication be restarted after elective spine surgery?; (3) When, how, and in whom should venous thromboembolism (VTE) chemoprophylaxis be started after elective spinal surgery? Summary of Background Data. VTE can lead to significant morbidity after adult spine surgery, yet postoperative VTE prophylaxis practices vary considerably. The management of preoperative AC/AP medication is similarly heterogeneous. Materials and Methods. Delphi method of consensus development consisting of three rounds (January 26, 2021, to June 21, 2021). Results. Twenty-one spine surgeons were invited, and 20 surgeons completed all rounds of questioning. Consensus (>70% agreement) was achieved in 26/27 items. Group consensus stated that preoperative Direct Oral Anticoagulants should be stopped two days before surgery, warfarin stopped five days before surgery, and all remaining AC/AP medication and aspirin should be stopped seven days before surgery. For restarting AC/AP medication postoperatively, consensus was achieved for low-risk/medium-risk/high-risk patients in 5/5 risk factors (VTE history/cardiac/ambulation status/anterior approach/operation). The low/medium/high thresholds were POD7/POD5/POD2, respectively. For VTE chemoprophylaxis, consensus was achieved for low-risk/medium-risk/high-risk patients in 12/13 risk factors (age/BMI/VTE history/cardiac/cancer/hormone therapy/operation/anterior approach/staged separate days/staged same days/operative time/transfusion). The one area that did not gain consensus was same-day staged surgery. The low-threshold/medium-threshold/high-threshold ranges were postoperative day 5 (POD5) or none/POD3-4/POD1-2, respectively. Additional VTE chemoprophylaxis considerations that gained consensus were POD1 defined as the morning after surgery regardless of operating finishing time, enoxaparin as the medication of choice, and standardized, rather than weight-based, dose given once per day. Conclusions. In the first known Delphi study to address anticoagulation/antiplatelet recommendations for elective spine surgery (preoperatively and postoperatively); our Delphi consensus recommendations from 20 spine surgeons achieved consensus on 26/27 items. These results will potentially help standardize the management of preoperative AC/AP medication and VTE chemoprophylaxis after adult elective spine surgery.

Venous thromboembolism (VTE) is a major complication in all patients with cancer. Compared with the general population, patients with multiple myeloma (MM) have a 9-fold increase in VTE risk, likely because of their malignancy, its treatments, and other additional patient-related factors. In MM, thromboembolism events tend to occur within 6 months of treatment initiation, regardless of treatment regimen; however, the use of immunomodulatory agents such as thalidomide or lenalidomide, especially in combination with dexamethasone or multiagent chemotherapy, is known to create a significant risk for VTE. Currently, official recommendations for VTE prophylaxis in MM outlined in various national guidelines or multidisciplinary society panels are based on expert opinion, because data from randomized controlled trials are scarce. Large studies which have mainly focused on the efficacy of thromboprophylaxis in patients with cancer at higher risk for VTE either had a very low representation of patients with MM, or excluded them all together, limiting our ability to draw evidence-based conclusions on how to effectively protect MM population from VTE. In this brief perspective, we highlight some of the greatest challenges that have hampered the field concerning the availability of high-quality clinical trial data for the formulation of best VTE prophylaxis strategies in patients with newly diagnosed MM, as well as the rationale for the latest updates in the NCCN Guidelines on this topic.

Abstract Standard treatment of catheter-associated upper extremity deep vein thrombosis (UE-DVT) is anticoagulation, although catheters are often removed for this indication. The optimal time for catheter removal and whether the act and/or timing of catheter removal is associated with pulmonary embolism (PE) remain unknown. A retrospective cohort study was performed at 8 participating institutions through the Venous thromboEmbolism Network US. Patients with hematologic malignancies and central venous catheter (CVC)–associated UE-DVT were included from 1 January 2010 through 31 December 2016. The primary outcome was objectively confirmed PE within 7 days of UE-DVT diagnosis in anticoagulated patients comparing early (≤48 hours) vs delayed (>48 hours) catheter removal. A total of 626 patients were included, among whom 480 were treated with anticoagulation. Among anticoagulated patients, 255 underwent early CVC removal, while 225 had delayed or no CVC removal; 146 patients received no anticoagulation, among whom 116 underwent CVC removal alone. PE within 7 days occurred in 2 patients (0.78%) with early removal compared with 1 patient (0.44%) with delayed or no CVC removal (P > .9). PE or any cause of death within 7 days occurred in 3 patients in both the early removal (1.18%) and delayed/no removal (1.33%) groups (P > .9). In patients treated with CVC removal only (no anticoagulation), there were no PEs but 3 deaths within 7 days. In patients with hematological malignancy and CVC-associated UE-DVT, early removal of CVCs was not associated with an increased risk of PE compared with delayed or no removal.

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.

Background: Standard treatment for catheter-associated upper extremity deep vein thrombosis (UEDVT) is anticoagulation. If catheter removal is otherwise indicated, it is unknown if catheter removal close to the time of initiation of anticoagulation is associated with a higher incidence of pulmonary embolization. Methods: A multicenter retrospective cohort study was performed at 8 participating institutions through the Venous thromboEmbolism Network US (VENUS). ICD-9/10 codes were used to identify patients with hematologic malignancies and upper extremity deep vein thrombosis (UEDVT) from 1/1/2010 through 12/31/2016. Identified patients underwent medical record review to verify diagnostic codes and determine if a catheter was associated with the upper extremity DVT and assess for outcomes. Patients were excluded if the UEDVT was not catheter provoked or if there were associated lower extremity DVT and/or pulmonary emboli. The anticoagulant start and finish date as well as the timing of the catheter removal, total follow up, and death were recorded. Patients started on anticoagulation at the time of their diagnosis were divided into two groups: 1) anticoagulation with delayed (> 48 hrs) or no catheter removal and 2) anticoagulation with early catheter removal (< 48 hrs). Outcomes were also assessed in patients with no anticoagulation initiation but catheter removal as the only treatment. The primary outcome was clinically identified pulmonary emboli within 7 days and the secondary outcome was pulmonary emboli or death from any cause within 7 days. Baseline characteristics were compared between groups using Χ2 for categorical variables, 2-tailed t-tests for continuous variables, and Wilcoxon rank-sum for nonparametric continuous variables. Fisher's exact test was used to evaluate the primary and secondary outcomes. Results: 663 patients with hematologic malignancies and isolated catheter-associated UEDVT underwent chart review. 512 patients were treated with anticoagulation of which 312 underwent early catheter removal while 200 had delayed or no catheter removal (Figure 1). 151 patients received no anticoagulation and 119 underwent catheter removal alone as the treatment for the DVT. Among patients who were treated with anticoagulation, the mean age was 52.6 years and 44% were male; age and sex did not differ between patients with early vs. delayed or no catheter removal (Table 1). Type of hematologic malignancy, type of central catheter, and DVT location were significantly different between groups. Patients with PICC lines were more likely to have early catheter removal (71% vs. 49%). The median platelet count was not significantly different among patients treated with anticoagulation, but was lower in patients treated with catheter removal only. Most patients were initially treated with low molecular weight heparins (LMWH) and anticoagulation treatment did not differ between groups. Pulmonary emboli within 7 days occurred in 2 patients (0.64%) with early catheter removal compared to 1 patient (0.5%) with delayed or no removal (p=1.0). Pulmonary emboli or any cause death within 7 days occurred in 3 patients (1.0%) with early removal compared to 3 patients (1.5%) with delayed or no removal (p=0.68). In patients treated with catheter removal only (no anticoagulation), there were no pulmonary emboli within 7 days and 3 deaths. All 3 patients with pulmonary emboli within 7 days had PICC lines and leukemia/MDS and the sites of most proximal DVT involvement were brachiocephalic veins (2 patients) and subclavian vein (1 patient). Conclusions: In patients with hematological malignancy and catheter-associated UEDVT, removal of catheters within 48 hours was not associated with increased risk of pulmonary emboli compared to delayed or no removal. Disclosures Billett: Albert Einstein College of Medicine: Patents & Royalties: Patent application pending for NETs AI software. Gaddh:Pfizer: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Hema Biologics: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics LLC: Membership on an entity's Board of Directors or advisory committees. Oo:Medical Education Speakers Network: Honoraria; Janssen and Janssen: Other: Research: site co-investigator . Jaglal:NOVARTIS: Consultancy. Streiff:Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi-Sankyo: Consultancy, Honoraria; Bayer: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Portola: Consultancy, Honoraria; Roche: Research Funding. Baumann Kreuziger:Vaccine Injury Compensation Program: Consultancy; CSL Behring: Consultancy.

Abstract On behalf of the ECOG-ACRIN Cancer Research Group Background: Venous thromboembolism (VTE) occurs in 2-12% of patients with acute leukemia (AL) despite disease and therapy-associated thrombocytopenia, and can be associated with significant morbidity and mortality. Due to limited high-quality studies, there are no evidence-based guidelines for VTE prophylaxis in this patient population. Based on our experience and the lack of consensus guidelines, we hypothesized that there would be a wide range in provider practice regarding methods of VTE prevention in patients with AL. To determine the current individual practices in North America, we devised a web-based survey of VTE prophylaxis practice among clinicians caring for patients with AL. Methods: An anonymous 19 question web-based survey, approved by the Johns Hopkins Institutional Review Board, was distributed by email to members of the ECOG-ACRIN Cancer Research Group on 10/22/14. Four reminders were sent at two-week intervals with the survey closing on 12/8/14. Results: Of the total 215 respondents, 64 were excluded for the following reasons: 52 did not directly manage medical care of AL patients, 3 referred AL patients to other centers, 5 left blank responses to all questions regarding VTE prophylaxis, 1 was a duplicate entry, and 3 described their position as support or office staff. One hundred fifty-one responses were eligible for analysis, with a response rate of 20.9% among physicians who treated leukemias. One hundred forty-seven were from the United States and 4 from Canada, representing 88 different institutions and 37 states or provinces. Overall, 47% and 45% of providers reported using pharmacologic VTE prophylaxis during induction and consolidation phases, respectively. Among the providers using pharmacologic prophylaxis, 60% designated 50,000/μL as the platelet count threshold below which they would hold prophylaxis and 26% used a platelet count of 30,000/μL. Fewer providers chose a platelet count of 20,000/μL (4%), 75,000/μL (4%), and 100,000/μL (2%). Lastly, 2% held prophylactic anticoagulation only in the setting of an active bleed and 2% reported variable thresholds. Approximately 15% of providers did not utilize any VTE prophylaxis while 36% used mechanical methods and ambulation. Among providers who did not recommend pharmacologic prophylaxis, the most commonly cited reasons were the perceived high risk of bleeding (51%), absence of data supporting use (38%), and perceived low risk of VTE (11%). Conclusions: These results demonstrate wide variation in clinician practice regarding VTE prevention in hospitalized AL patients during induction and consolidation therapy. Our findings emphasize the need to develop standardized, evidence-based guidelines in this at-risk population. VTE: venous thromboembolism, AL: acute leukemia, SC: subcutaneous, TED: thromboembolic deterrant stockings, SCD: sequential compression device Figure 1. Practice patterns of VTE prophylaxis for AL patients during induction and consolidation therapies Figure 1. Practice patterns of VTE prophylaxis for AL patients during induction and consolidation therapies Disclosures Barbarotta: Celgene, BMS, Novartis: Speakers Bureau. Prebet:CELGENE: Research Funding. Gore:Celgene: Consultancy, Honoraria, Research Funding.

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.

Introduction Parenteral anticoagulants may improve outcomes in patients with cancer by reducing risk of venous thromboembolic disease and through a direct antitumour effect. Study-level systematic reviews indicate a reduction in venous thromboembolism and provide moderate confidence that a small survival benefit exists. It remains unclear if any patient subgroups experience potential benefits. Methods and analysis First, we will perform a comprehensive systematic search of MEDLINE, EMBASE and The Cochrane Library, hand search scientific conference abstracts and check clinical trials registries for randomised control trials of participants with solid cancers who are administered parenteral anticoagulants. We anticipate identifying at least 15 trials, exceeding 9000 participants. Second, we will perform an individual participant data meta-analysis to explore the magnitude of survival benefit and address whether subgroups of patients are more likely to benefit from parenteral anticoagulants. All analyses will follow the intention-to-treat principle. For our primary outcome, mortality, we will use multivariable hierarchical models with patient-level variables as fixed effects and a categorical trial variable as a random effect. We will adjust analysis for important prognostic characteristics. To investigate whether intervention effects vary by predefined subgroups of patients, we will test interaction terms in the statistical model. Furthermore, we will develop a risk-prediction model for venous thromboembolism, with a focus on control patients of randomised trials. Ethics and dissemination Aside from maintaining participant anonymity, there are no major ethical concerns. This will be the first individual participant data meta-analysis addressing heparin use among patients with cancer and will directly influence recommendations in clinical practice guidelines. Major cancer guideline development organisations will use eventual results to inform their guideline recommendations. Several knowledge users will disseminate results through presentations at clinical rounds as well as national and international conferences. We will prepare an evidence brief and facilitate dialogue to engage policymakers and stakeholders in acting on findings. Trial registration number PROSPERO CRD42013003526.