ALBERT

Description: Background:The relationship between metastatic colorectal cancer (CRC) and venous thromboembolism (VTE) is not well defined in the modern treatment era. Previous population-based studies date back to a period marked by inpatient intravenous heparin therapy and inferior survival due to paucity of therapeutic anti-cancer options, and before the advent of newer therapies including oxaliplatin, irinotecan, and anti-angiogenic treatment with bevacizumab. The objectives of this retrospective study were to examine the impact of multiple putative risk factors on VTE incidence in a large representative modern cohort of older patients with metastatic CRC. Methods:We performed a retrospective analysis of SEER-Medicare data on elderly patients with metastatic CRC diagnosed in 2004-2011. VTE and associated risk factors were analyzed using multivariate Cox proportional hazards models adjusted for sex, age at diagnosis, race, ethnicity, tumor anatomy (left/right/unknown), calendar year of diagnosis, Charlson comorbidity score, location of SEER registry and urban residence, with time-varying covariates for use of cancer therapies. Results:Of 339,778 records, 11,086 metastatic colon cancer cases were identified. 1,338 cases had VTE with a cumulative incidence of 13% at 1 year and 19% at 3 years. The mean age was 77.9 years (range 65-106). 49.7% were women and 83.5% white. 60.5% had a Charlson comorbidity score of zero at diagnosis; 6% had scores of 6-18. Significant predictors of VTE included female sex (Hazard Ratio (HR) 1.22; 95% Confidence Interval (CI) 1.10, 1.36; P

Description: Abstract 3178 Background: HMG CoA reductase inhibitors (statins) were recently reported to reduce the rate of venous thromboembolism (VTE) in healthy people. Statins reduce levels of inflammation biomarkers, however the mechanism for a reduction in VTE risk is unknown. We studied cross-sectional associations of statin use with hemostatic factors related to venous thrombosis risk in a large cohort of healthy people. Methods: Cross-sectional analyses were performed in the Multi-Ethnic Study of Atherosclerosis (MESA), a cohort study of 6814 healthy men and women age 45–84, free of clinical cardiovascular disease at baseline; 1001 were using statins. Twenty three warfarin users were excluded. Age, race, and sex-adjusted mean hemostatic factor levels were compared between statin users and nonusers, and multivariable linear regression models were used to assess associations of statin use with hemostasis factors, adjusted for age, race/ethnicity, education, income, hormone replacement therapy (in women) and major cardiovascular risk factors. Results: The table shows that those using statins had significantly lower levels of D-dimer, C-reactive protein and factor VIII than non-users. Homocysteine and von Willebrand factor did not differ by statin use. Specific adjustment for LDL and triglycerides did not attenuate the observed differences in these factors by statin use. Conclusions: Findings of lower D-dimer, factor VIII and C-reactive protein levels with statin use suggest mechanisms whereby statins might lower VTE risk. These associations were not explained by lipid levels on treatment. A prospective study linking these biochemical differences to VTE outcomes is warranted. Disclosures: No relevant conflicts of interest to declare.

Description: Background. Cancer patients often display procoagulant activity and are at a risk for developing venous thromboembolism (VTE). Multiple mechanisms may explain this procoagulant state, such as tumor cell expression of tissue factor (TF), host tissue response to tumor formation and also contributions from comorbid factors and treatment. We previously observed elevated levels of traditional biomarkers of coagulation (such as D-dimer, CRP, etc.) in patients with advanced cancer on therapy enrolled in a randomized trial comparing rosuvastatin versus placebo. In this study, we evaluated the frequency and concentration of endogenous plasma TF, Factor (F)XIa and FIXa in the cancer patient population analyzed for traditional coagulation biomarkers. The choice of new analytes was based on previous studies in which these 3 proteins were detected and quantitated in patients with cardiovascular diseases, inflammation, and trauma - often present over the course of several days to even weeks. By our knowledge, there are no published studies of the presence of FXIa and/or FIXa in cancer patients. Methods. Thirty-seven adult cancer patients receiving systemic therapy were originally enrolled in a randomized crossover trial comparing effects of rosuvastatin versus placebo on biomarkers of VTE. Inclusion criteria included locally-advanced or metastatic cancer, estimated survival time of greater than 6 months, and anticipated duration of therapy of at least 3 months. Patients on antithrombotic or statin therapy were excluded. Blood was collected on up to 4 occasions; at the start and end of each of 2 treatment periods corresponding to 2 cycles of systemic therapy with a 3-4 week washout period. Citrate plasma was prepared, frozen and stored at -80C. The assay, performed in previously unthawed and contact-pathway inhibited plasma, is based on a response of the lag phase of thrombin generation to corresponding monoclonal inhibitory antibodies (αFXIa-2, αFIXa-91 and αTF-5; all at 0.1 mg/mL). Concentrations of TF, FXIa and FIXa were calculated from corresponding calibration curves built by titrating purified proteins into multi-donor pooled plasma from healthy individuals. Results. A total of 116 blood samples were collected (not all patients were able to complete their regime) and analyzed for endogenous levels of TF, FXIa and FIXa (see table). Overall, rosuvastatin treatment did not have any significant impact on the levels and frequency of these 3 proteins. For the samples obtained from each patient's first blood draw (n = 37) there was a weak correlation between FXIa and FIXa levels (R = 0.37, P = 0.02) and a moderate correlation between FXIa and TF levels (R = 0.57, P 〈 0.001), while no correlation between FIXa and TF was observed (R = 0.02, P = 0.91). Conclusions. 1) A portion of patients with advanced cancer had active TF in their plasma while the majority, for the first time reported, had active FXIa and FIXa; 2) No pronounced differences were observed between the frequency and concentrations of these proteins at baseline versus later time-points; 3) There was a weak correlation between FXIa and FIXa and a moderate correlation between FXIa and TF, suggesting the TF-pathway is driving the majority of FXIa generation, although contribution from the contact pathway cannot be excluded; 4) Rosuvastatin treatment did not lead to any significant changes in the levels of TF, FXIa and/or FIXa. Table Table. Disclosures No relevant conflicts of interest to declare.

Description: Background: Recent clinical trials have evaluated the safety and efficacy of direct oral anticoagulant (DOAC) therapy for venous thromboembolism (VTE) prophylaxis in cancer outpatients at high risk for thrombosis. Bleeding risk in these trials were approximately 2% over the first 6 months of therapy. For individual patients, the utility of prophylactic anticoagulation (AC) depends on an acceptable safety profile between bleeding and thrombosis. We investigated whether ambulatory cancer patients on contemporary cancer-directed therapies and prophylactic AC had an increased risk of major bleeds over the first 6 months of therapy. Methods: As part of a single-center prospective cohort study, we assessed consecutive ambulatory patients initiating cancer-directed treatment, risk-stratified these patients for VTE using the Khorana score and educated them about VTE. High risk patients (Khorana score ≥3) were offered prophylactic AC. Major bleeding events and minor bleeding events (based on ISTH standard definitions) were prospectively captured via billing code screening and confirmed by physician review of the medical record. Logistic regression was used to compare the odds of developing a major bleed within 6 months in those who received prophylactic AC compared to those that did not. Results: A total of 1,210 patients were enrolled from October 2015 - June 2018, of which, 640 were women (52.9%). The most common cancers were gastrointestinal 270 (22%), lung 213 (18%), and breast 198 (16%). There were 393 patients (32%) with a Khorana score of 0, 706 (58%) with a Khorana score of 1-2, and 111 (9%) with a score of ≥3. A total of 421 patients received any AC (LMWH or DOAC). Of these, 282 received a prophylactic dose anticoagulant and 139 were receiving a full dose anticoagulant prior to enrolling for other medical reasons. Prophylactic dose anticoagulants prescribed included apixaban in 107 (41%), rivaroxaban in 6 (2.3%), enoxaparin in 119 (45.7%), and other heparin products in 50 (19.2%). A total of 27 (2.33%) major bleeds and 22 (1.81%) minor bleeds occurred within the first 6 months of starting therapy. Of these bleeding events, 8 (2.8%) occurred in those on prophylactic AC, and 6 (4.3%) occurred in those on full dose AC. The odds ratio (OR) of developing a major bleed on any type of AC was 1.78 [CI 0.817-3.88]. The OR of major bleeding on prophylactic AC was 1.49 [CI 0.64-3.479]. The OR of major bleed was highest in lung cancer patients on prophylactic AC (OR 2.81, CI 1.27-6.25). Men, when compared to women, were more likely to bleed on prophylactic AC in the first six month (OR 0.2; CI 0.07-0.52). The OR for major bleed with each 1 year increase in age was 1.02 (CI 0.99, 1.06). The OR of bleeding with a high risk Khorana score (≥3) compared to a lower score was 1.04 (CI 0.73-1.50). Conclusion: During the first six months of therapy, prophylactic AC was associated with an increased risk of major bleeding events in patients on cancer-directed therapy. In this study, the rate of major bleeding was similar as compared to published clinical trials. Neither age nor higher Khorana score were associated with an increased risk of major bleeds in patients on prophylactic AC. The finding that men, when compared to women, and patients with lung cancer may have an increased risk of major bleeding while on prophylactic AC and cancer-directed chemotherapy suggests these groups may warrant both increased education and monitoring to ensure safety while on prophylactic AC. Disclosures No relevant conflicts of interest to declare.

Description: Background: The Khorana VTE risk score is a validated tool to predict the 6 month VTE rate for patients starting chemotherapy. It includes cancer type, obesity, anemia, leukocytosis, and thrombocytosis. Patients with cancer are living longer, and VTE risk continues beyond 6 months. The influence of known VTE risk factors that are not included in the Khorana score on VTE risk in cancer patients, such as hospitalization (which varies over time), older age and prior history of VTE is not known. Methods: Among patients with cancer starting chemotherapy from 2012-14 at the University of Vermont Cancer Center, VTE was ascertained for up to 3 years using ICD codes and confirmed by manual chart review. Prior VTE was defined as VTE 〉3 months prior to starting chemotherapy and body mass index (BMI) and laboratory values were assessed within 1 week prior to starting chemotherapy. We performed two series of analyses. In the first, logistic regression was used to assess the performance of the Khorana score for VTE prediction within 6 months of chemotherapy start before and after the addition of the VTE risk factors of age and prior VTE. In a second analysis, we used Cox proportional hazard models (which incorporate time-to-event data) and all VTE events, with up to 3 years of follow-up, and additionally assessed hospitalization and time-periods after hospitalization as time-varying covariates. The area under the receiver operating characteristic curve (AUC) of the Khorana score was then determined before and after addition of significant traditional risk factors found in univariate analysis. Results: Among 1,583 patients with a mean age of 60 and 48% male, 187 developed VTE (11.8%) with 129 cases occurring within 6 months of chemotherapy start. Cancer types in the study included 229 breast (14.5%), 186 lung (11.8%), 174 lymphoma (11%), 105 gynecologic (6.7%), 71 pancreas (4.4%), 30 bladder (1.9%), 18 testicular (1.1%), 17 stomach (1%) and 753 other types of cancer (47.6%), including cancer types not included in the original Khorana score. The table shows the unadjusted and adjusted associations of risk factors with VTE, assessing both the first 6 months of chemotherapy and the entire 3 year study period. In the 6-month analysis, none of the traditional risk factors were significantly associated with VTE (Table). The c-statistic for the Khorana model was 0.61 (95% CI 0.56, 0.65). In the 3-year analysis, male sex, prior VTE, and hospitalization as a time-varying exposure were associated with an increased hazard of VTE (Table). Hospitalization, both within the past 90 days (HR 2.87, 95% CI 2.06, 4.00) and the past 30 days (HR 3.09, 95% CI 2.12, 4.51) was associated with VTE, while the time period encompassing hospitalization itself (HR 1.75, 95% CI 0.72, 4.28) did not reach statistical significance. The C-index for the Khorana score over 3 years was 0.59, and with addition of male sex and prior VTE this was 0.61. Conclusions: In a real-world patient population, the Khorana score was again validated for predicting 6-month rate of VTE after initiating chemotherapy. Further, patients remained at risk of VTE beyond 6 months, and when time-to-event data were incorporated into risk assessment, male sex, prior history of VTE, and hospitalization were important risk factors. These data demonstrate that risk factors for cancer-related VTE vary over time and highlight the need to re-evaluate VTE risk of the course of a patient's treatment. Disclosures No relevant conflicts of interest to declare.