Direct oral anticoagulants or vitamin K antagonists in emergencies: comparison of management in an observational study.

Background: Restoring hemostasis in patients on oral anticoagulants presenting with major hemorrhage (MH) or before surgical intervention has changed, with the replacement of vitamin K antagonist (VKA) with direct oral anticoagulants (DOACs). Objectives: To observe the difference in urgent hemostatic management between patients on VKA and those on DOACs. Methods: A multicenter observational study evaluated the variation in laboratory testing, hemostatic management, mortality, and hospital length of stay (LOS) in patients on VKA or DOACs presenting with MH or urgent hemostatic restoration. Results: Of the 1194 patients analyzed, 783 had MH (61% VKA) and 411 required urgent hemostatic restoration before surgery (56% VKA). Compared to the international normalized ratio (97.6%), plasma DOAC levels were measured less frequently (<45%), and the time taken from admission for the coagulation sample to reach the laboratory varied widely (median, 52.3 minutes; IQR, 24.8-206.7). No significant plasma DOAC level (<50 ng/mL) was found in up to 19% of patients. There was a poor relationship between plasma DOAC level and the usage of a hemostatic agent. When compared with patients receiving VKA (96.5%) or dabigatran (93.7%), fewer patients prescribed a factor Xa inhibitor (75.5%) received a prohemostatic reversal agent. The overall 30-day mortality for MH (mean: 17.8%) and length of stay (LOS) (median: 8.7 days) was similar between VKA and DOAC patients. Conclusion: In DOAC patients, when compared to those receiving VKA, plasma DOAC levels were measured less frequently than the international normalized ratio and had a poor relationship with administering a hemostatic reversal agent. In addition, following MH, mortality and LOS were similar between VKA and DOAC patients.

Adenosine 2A Receptor Activation Amplifies Ibrutinib Antiplatelet Effect; Implications in Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia patients have an increased bleeding risk with the introduction of Bruton tyrosine kinase (BTK) inhibitors. BTK is a signaling effector downstream of the platelet GPVI receptor. Innate platelet dysfunction in CLL patients and the contribution of the leukemia microenvironment to the anti-platelet effect of BTK inhibitors are still not well defined. Herein, we investigated platelet function in stable, untreated CLL patients in comparison to age-matched healthy subjects as control. Secondly, we proposed a novel mechanism of platelet dysfunction via the adenosinergic pathway during BTK inhibitor therapy. Our data indicate that the nucleotidase that produces adenosine, CD73, was expressed on one-third of B-cells in CLL patients. Inhibition of CD73 improved platelet response to ADP in the blood of CLL patients ex vivo. Using healthy platelets, we show that adenosine 2A (A2A) receptor activation amplifies the anti-platelet effect of ibrutinib (10 nM). Ibrutinib plus an A2A agonist-but not ibrutinib as a single agent-significantly inhibited collagen (10 µg/mL)-induced platelet aggregation. Mechanistically, A2A activation attenuated collagen-mediated inhibition of p-VASP and synergized with ibrutinib to inhibit the phosphorylation of AKT, ERK and SYK kinases. This manuscript highlights the potential role of adenosine generated by the microenvironment in ibrutinib-associated bleeding in CLL patients.

Cannabis as an Anticancer Agent: A Review of Clinical Data and Assessment of Case Reports.

Background: Pre-clinical studies have demonstrated the potential anticancer activity of cannabinoids, yet little clinical data exist to support this. Nearly 40% of patients with cancer using cannabis believe it will treat their cancer with numerous anecdotal reports shared online through social media platforms. Case reports have been published in peer-reviewed journals, but often lack key clinical information to validate anticancer claims. Methods: We reviewed literature in PubMed and EBSCO databases that evaluated the relationship between cannabis or the endocannabinoid system and potential anticancer activity. We also reviewed online sources, books, and ClinicalTrials.gov for reports or studies on using cannabis as cancer treatment. All case reports published in peer-reviewed journals were compiled and appraised as weak, moderate, or strong based on the quality of evidence provided supporting an anticancer effect. Strong reports met three criteria; (a) active cancer at time of cannabis administration, (b) validated laboratory or radiographic responses were reported, and (c) cannabis used without concurrent anticancer treatments. Results: Of the 207 pre-clinical articles reviewed, 107 (52%) were pre-clinical studies with original data. A total of 77 unique case reports described patients with various cancers (breast, central nervous system, gynecological, leukemia, lung, prostate, and pancreatic) using cannabis. Our appraisal showed 14% of the case reports were considered strong, 5% moderate, and the remaining 81% were weak. Ten percent of cases were in pediatric patients. Cannabidiol use was most often reported as the anticancer cannabinoid with daily doses ranging from 10 to 800 mg. Tetrahydrocannabinol use was reported in six studies, with doses ranging from 4.8 to 7.5 mg. Two small trials published data on survival in patients with recurrent glioblastoma multiforme. Conclusion: This review of clinical data suggests most published, peer-reviewed case reports provide insufficient data to support the claim for cannabis as an anticancer agent, and should not be used in place of evidence-based, traditional treatments outside of a clinical trial. No strong clinical trial data exist to confirm the pre-clinical studies that suggest cannabinoids may have an anticancer benefit. Future studies exploring anticancer potential of cannabis in patients with metastatic cancers who have not responded to traditional therapy are needed.

A randomized trial of medical cannabis in patients with stage IV cancers to assess feasibility, dose requirements, impact on pain and opioid use, safety, and overall patient satisfaction.

PURPOSE: The prevalence of medical cannabis (MC) use in patients with cancer is growing, but questions about safety, efficacy, and dosing remain. Conducting randomized, controlled trials (RCTs) using state-sponsored MC programs is novel and could provide data needed to guide patients and providers. METHODS: A pilot RCT of patients with stage IV cancer requiring opioids was conducted. Thirty patients were randomized 1:1 to early cannabis (EC, n = 15) versus delayed start cannabis (DC, n = 15). The EC group obtained 3 months (3 M) of MC through a state program at no charge, while the DC group received standard oncology care without MC for the first 3 M. Patients met with licensed pharmacists at one of two MC dispensaries to determine a suggested MC dosing, formulation, and route. Patients completed surveys on pain levels, opioid/MC use, side effects, and overall satisfaction with the study. RESULTS: Interest in the study was high as 36% of patients who met eligibility criteria ultimately enrolled. The estimated mean daily THC and CBD allotments at 3 M were 34 mg and 17 mg, respectively. A higher proportion of EC patients achieved a reduction in opioid use and improved pain control. No serious safety issues were reported, and patients reported high satisfaction. CONCLUSION: Conducting RCTs using a state cannabis program is feasible. The addition of MC to standard oncology care was well-tolerated and may lead to improved pain control and lower opioid requirements. Conducting larger RCTs with MC in state-sponsored programs may guide oncology providers on how to safely and effectively incorporate MC for interested patients.

Estradiol-Responsive miR-365a-3p Interacts with Tissue Factor 3'UTR to Modulate Tissue Factor-Initiated Thrombin Generation.

BACKGROUND: High estradiol (E2) levels are linked to an increased risk of venous thromboembolism; however, the underlying molecular mechanism(s) remain poorly understood. We previously identified an E2-responsive microRNA (miR), miR-494-3p, that downregulates protein S expression, and posited additional coagulation factors, such as tissue factor, may be regulated in a similar manner via miRs. OBJECTIVES: To evaluate the coagulation capacity of cohorts with high physiological E2, and to further characterize novel E2-responsive miR and miR regulation on tissue factor in E2-related hypercoagulability. METHODS: Ceveron Alpha thrombin generation assay (TGA) was used to assess plasma coagulation profile of three cohorts. The effect of physiological levels of E2, 10 nM, on miR expression in HuH-7 cells was compared using NanoString nCounter and validated with independent assays. The effect of tissue factor-interacting miR was confirmed by dual-luciferase reporter assays, immunoblotting, flow cytometry, biochemistry assays, and TGA. RESULTS: Plasma samples from pregnant women and women on the contraceptive pill were confirmed to be hypercoagulable (compared with sex-matched controls). At equivalent and high physiological levels of E2, miR-365a-3p displayed concordant E2 downregulation in two independent miR quantification platforms, and tissue factor protein was upregulated by E2 treatment. Direct interaction between miR-365a-3p and F3-3'UTR was confirmed and overexpression of miR-365a-3p led to a decrease of (1) tissue factor mRNA transcripts, (2) protein levels, (3) activity, and (4) tissue factor-initiated thrombin generation. CONCLUSION: miR-365a-3p is a novel tissue factor regulator. High E2 concentrations induce a hypercoagulable state via a miR network specific for coagulation factors.

Impact of Pain, Opioids, and the Mu-opioid Receptor on Progression and Survival in Patients With Newly Diagnosed Stage IV Pancreatic Cancer.

OBJECTIVES: Pancreatic adenocarcinoma is frequently associated with pain requiring opioid therapy. Opioids, however, have been implicated in causing tumor progression, ultimately shortening survival. We examined the impact of pain, opioid use, and the mu-opioid receptor (MOP-R) expression in tumor tissue on progression-free survival and overall survival of patients with metastatic pancreatic cancer. METHODS: We identified 103 patients with metastatic pancreatic adenocarcinoma receiving chemotherapy and abstracted data from Tumor Registry, in addition to pain, opioid exposure, carbohydrate antigen 19-9 values, survival, and imaging response. MOP-R expression was evaluated using an immunohistochemistry assay. The association of variables with progression-free survival and overall survival was analyzed in univariate and multivariate models. RESULTS: Patients with low opioid use (<5 mg oral morphine equivalent/d) survived longer than patients with high opioid (HO) use (≥5 mg oral morphine equivalent/d) (median overall survival of 315 vs. 150 d; hazard ratio [HR]=1.79; 95% confidence interval [CI]: 1.13, 2.84). This effect persisted on multivariate models (adjusted HR=2.76; 95% CI: 1.39, 5.48). Low opioid patients tended to respond better to treatment than HO patients, based on carbohydrate antigen 19-9. Patients with low MOP-R expression had longer median survival (230 vs. 193 d), though the HR was not significant (1.15; 95% CI: 0.71, 1.88). Baseline pain was not associated with outcomes. CONCLUSION: In patients with metastatic pancreatic adenocarcinoma, HO use is associated with decreased survival, but the severity of baseline pain and MOP-R expression score in tumor tissue does not correlate with clinical outcomes.

Laboratory testing for activated protein C resistance: rivaroxaban induced interference and a comparative evaluation of andexanet alfa and DOAC Stop to neutralise interference.

Background Investigation of hemostasis is problematic when patients are on anticoagulant therapy. Rivaroxaban especially causes substantial interference, extending many clot-based tests, thereby leading to false positive or negative events. In particular, rivaroxaban affects some assays for activated protein C resistance (APCR). Methods We assessed, in an international setting, cross laboratory (n = 31) testing using four samples to evaluate rivaroxaban induced interference in APCR testing, and whether this interference could be neutralised. The samples comprised: (A) pool of normal plasma (APCR-negative control); (B) this normal pool spiked with rivaroxaban (200 ng/mL) to create rivaroxaban-induced interference (potential 'false' positive APCR event sample); (C) the rivaroxaban sample subsequently treated with a commercial direct oral anticoagulant 'DOAC-neutraliser' (DOAC Stop), or (D) treated with andexanet alfa (200 µg/mL). Testing was performed blind to sample type. Results The rivaroxaban-spiked sample generated false positive APCR results for some, but unexpectedly not most APCR-tests. The sample treated with DOAC Stop evidenced a correction in the rivaroxaban-affected APCR assays, and did not otherwise adversely affect the rivaroxaban 'unaffected' APCR assays. The andexanet alfa-treated sample did not evidence correction of the false positive APCR, and instead unexpectedly exacerbated false positive APCR status with many tests. Conclusions DOAC Stop was able to neutralise any APCR interference induced by rivaroxaban. In contrast, andexanet alfa did not negate such interference, and instead unexpectedly created more false-positive APCR events.

Reducing the effect of DOAC interference in laboratory testing for factor VIII and factor IX: A comparative study using DOAC Stop and andexanet alfa to neutralize rivaroxaban effects.

INTRODUCTION: Investigation of factors (F) VIII and IX is common, with testing important for diagnosis or exclusion of haemophilia A or B, associated acquired conditions and factor inhibitors. Rivaroxaban, a common direct anti-Xa agent, causes significant interference in clotting assays, including substantial false reduction of factor levels. AIM: To assess whether rivaroxaban-induced interference of FVIII and FIX testing could be neutralized. MATERIALS AND METHODS: An international, cross-laboratory exercise for FVIII (n = 84) and FIX (n = 74), using four samples: (A) pool of normal plasma; (B) pool spiked with rivaroxaban (200 ng/mL); (C) rivaroxaban sample subsequently treated with 'DOAC Stop' and; (D) rivaroxaban sample treated with andexanet alfa (200 µg/mL). Testing performed blind to sample type. RESULTS: All laboratories reported normal FIX and 94% reported normal FVIII in the pool sample. Instead, 55% and 95%, respectively, reported abnormal FIX and FVIII levels for the rivaroxaban sample. DOAC Stop treatment evidenced a correction in most laboratories (100% reported normal FIX and 86% normal FVIII). Andexanet alfa provided intermediate results, with many laboratories still reporting abnormal results (59% for FVIII, 18% for FIX). We also identified reagent-specific issues. CONCLUSIONS: As expected, rivaroxaban caused false low values of FVIII and FIX. This might lead to increased testing to identify the cause of low factor levels and potentially lead to false identification of (mild) haemophilia A or B if unrecognized by clinicians/laboratories. DOAC Stop effectively neutralized the rivaroxaban effect, but andexanet alfa less so, with reagent-related effects evident, and thus, false low values sometimes persisted.

Collection of electronic patient-reported symptoms in patients with advanced cancer using Epic MyChart surveys.

BACKGROUND: Use of electronic patient-reported outcomes (ePROs) in routine cancer care can help identify troublesome symptoms and facilitate discussions between patients and clinicians and has been shown to improve patient satisfaction, quality of life, and survival. METHODS: Eighty patients with stage IV non-hematologic malignancies on chemotherapy participated. Patient-Reported Symptom Monitoring (PRSM) surveys were sent every 14 days via the Epic MyChart system over a 12-week period. Surveys were offered via phone or paper if patients failed to complete the automated MyChart survey by day 16. Severe symptoms or concerning symptom trends were automatically highlighted in reports for clinic staff. Patients reporting severe symptoms were routed to oncology nursing triage for standard symptom care management. RESULTS: Two hundred seventy-one surveys were sent during the 12-week study period. One hundred eighty-three surveys (66%) were completed, with 68% completed electronically via MyChart, 25% by paper, and 7% by phone call from a research coordinator. At least one severe symptom was reported on 36% of all surveys. However, most severe symptoms did not result in urgent triage follow-up because they were already being addressed and/or patients felt they were manageable. Patients and clinicians generally said the ePRO was efficient and helpful for addressing distressing symptoms and would use it in routine oncology care. CONCLUSION: ePROs can be integrated into the electronic health record using the Epic MyChart system. Patients and clinicians gave positive feedback on the system. Monitoring symptoms in real time may soon become part of standard oncology practice and requires seamless methods for collection.

Neutralising rivaroxaban induced interference in laboratory testing for lupus anticoagulant (LA): A comparative study using DOAC Stop and andexanet alfa.

INTRODUCTION: Lupus anticoagulant (LA) investigation in patients on anticoagulant therapy is problematic. Rivaroxaban in particular causes significant interference, prolonging both LA screening and confirmation tests, and falsely raising LA screen/confirm ratios, leading to potential false identification of LA. The Russell Viper Venom Time (RVVT) assay, key to the investigation of LA, is especially sensitive to rivaroxaban. MATERIALS AND METHODS: We assessed cross laboratory (n = 82) testing of four samples to investigate whether rivaroxaban induced interference in LA testing could be neutralised. Testing was performed blind to sample type. The samples comprised: (A) A pool of normal plasma (LA-negative control); (B) sample A spiked with rivaroxaban (200 ng/mL) to create rivaroxaban-induced interference (LA 'false' positive sample); (C) sample B subsequently treated with a commercial 'DOAC-neutraliser' (DOAC Stop); (D) sample B treated with andexanet alfa (200 µg/mL). RESULTS: As expected, the rivaroxaban-spiked sample (B) caused prolongation of most LA-tests, and also generated a falsely prolonged RVVT screen/confirm ratio (median 1.37, compared to 0.97 for sample A). The sample (C) treated with DOAC Stop evidenced a correction in LA-test clotting times, as well as neutralising the false positive LA (median RVVT screen/confirm ratio of 0.99). Although the andexanet alfa treated sample (D) also yielded a low median RVVT screen/confirm ratio of 0.88, it did not fully correct LA-test clotting times. Consistent with test findings, all laboratories interpreted samples A and C as being LA-negative. For sample B (rivaroxaban), 45.3% identified this as LA positive, and 38.7% identified LA interference. Most (61.3%) also identified sample D as LA negative, with the remainder (38.7%) identifying LA interference. CONCLUSIONS: DOAC Stop was able to neutralise the false LA activity induced by rivaroxaban, both in terms of clot-times and LA ratios. In contrast, whilst andexanet alfa negated the rivaroxaban-prolonged LA-ratio, it did not fully correct clot-times, leaving some residual LA interference, and requiring additional testing to investigate prolonged clotting times.

Impact of diabetes and hyperglycemia on health care utilization, infection risk, and survival in patients with cancer receiving glucocorticoids with chemotherapy.

BACKGROUND: Glucocorticoids are commonly used in chemotherapy regimens and may lead to hyperglycemia and increased infection rates. METHODS: We performed a retrospective analysis on 1781 patients who received intravenous chemotherapy with glucocorticoids between 2010 and 2015. Data was obtained using electronic medical record, billing modules, and tumor registry. We compared new infections and survival between patients with and without diabetes, after adjusting for demographic and cancer-related variables. RESULTS: In the first 12 months following chemotherapy, patients with diabetes (n = 330) had higher rates of hospital admissions (70.9% vs 57.4%), more infection-related admissions (37.0% vs 29.2%), and increased rates of new infections (61.2% vs 49.2%) when compared to patients without diabetes (n = 1451). One-year survival was worse among patients with diabetes (67.3% vs 78.3%), and in patients with at least one elevated glucose following chemotherapy (60.8% vs 78.5). After adjusting for cancer stage, age, and gender, diabetes history increased the odds of dying within one year after diagnosis by 86% (OR 1.86, 95% CI (1.37-2.52)) and of new infections by 68% (OR 1.68, 95% CI (1.26-2.24)). CONCLUSIONS: Among patients with cancer receiving intravenous chemotherapy with glucocorticoids we demonstrate those with diabetes have more hospital admissions, increased rates of infections, and worse survival.

Circulating MicroRNA as Thrombosis Sentinels: Caveats and Considerations.

The small noncoding RNAs, microRNAs (or miRNAs), have been implicated in a myriad of diseases and accumulating evidence indicate their potential high value as diagnostic biomarkers. Although their roles in hemostasis and coagulation pathways are less defined, many studies have demonstrated their participation in regulating key factors of hemostasis. However, the mounting challenges associated with the accurate measurement of circulating miRNAs and the involvement of platelet activation in contributing to the circulating miRNA expression profile introduce further complexity to the study of thrombosis-associated miRNAs. This review outlines the current knowledge of miRNAs that have been postulated to regulate key hemostatic factors, and miRNA diagnostic panels in thrombotic disease, with a focus on experimental fundamentals, such as selecting condition-specific reference controls, considerations that are crucial for accurate evaluation of miRNAs in the context of disease biomarkers.

Construction of a Bivalent Thrombin Binding Aptamer and Its Antidote with Improved Properties.

Aptamers are short synthetic DNA or RNA oligonucleotides that adopt secondary and tertiary conformations based on Watson-Crick base-pairing interactions and can be used to target a range of different molecules. Two aptamers, HD1 and HD22, that bind to exosites I and II of the human thrombin molecule, respectively, have been extensively studied due to their anticoagulant potentials. However, a fundamental issue preventing the clinical translation of many aptamers is degradation by nucleases and reduced pharmacokinetic properties requiring higher dosing regimens more often. In this study, we have chemically modified the design of previously described thrombin binding aptamers targeting exosites I, HD1, and exosite II, HD22. The individual aptamers were first modified with an inverted deoxythymidine nucleotide, and then constructed bivalent aptamers by connecting the HD1 and HD22 aptamers either through a triethylene glycol (TEG) linkage or four consecutive deoxythymidines together with an inverted deoxythymidine nucleotide at the 3'-end. The anticoagulation potential, the reversal of coagulation with different antidote sequences, and the nuclease stability of the aptamers were then investigated. The results showed that a bivalent aptamer RNV220 containing an inverted deoxythymidine and a TEG linkage chemistry significantly enhanced the anticoagulation properties in blood plasma and nuclease stability compared to the existing aptamer designs. Furthermore, a bivalent antidote sequence RNV220AD efficiently reversed the anticoagulation effect of RNV220 in blood plasma. Based on our results, we believe that RNV220 could be developed as a potential anticoagulant therapeutic molecule.

The tissue factor pathway in ischemic stroke.

To explore the role of the the tissue factor (TF) pathway in ischemic stroke. We measured blood concentrations of markers of the TF pathway [TF antigen, free tissue factor pathway inhibitor antigen (TFPIf) and activity (TFPIac), and activated factor VII (FVIIa)] within 7 days (acute phase) and after 3-6 months (convalescence) in 150 patients with first-ever ischemic stroke and 150 community controls. During the acute phase, TF antigen and TFPIf were not significantly altered but TFPIac was increased (mean 1.27 versus 1.13 U/ml, P = 0.04) and FVIIa was decreased in cases compared with controls (mean 43.3 versus 57.9 mU/ml, P = 0.0004). After adjusting for baseline differences between cases and controls, increasing quartiles of TFPIf were independently associated with reduced odds of stroke, and reducing quartiles of FVIIa and increasing quartiles of TFPIac with increased odds of stroke. During the convalescent phase, FVIIa and TFPIac returned to normal but TF antigen and TFPIf were significantly decreased compared with controls [median TF antigen, 110 (follow-up) versus 155 pg/ml (controls), P = 0.0008; median TFPIf, 15.5 (follow-up) versus 23.3 ng/ml (controls), P = 0.002]. Alterations of blood concentrations of TF pathway markers are common in patients with acute ischemic stroke. The mechanisms are unclear but may relate to enhanced formation of TF-FVIIa complexes and upregulation and release of TFPI during the acute phase, and ongoing consumption of TF antigen and TFPIf during the chronic phase as the atherosclerotic plaque heals.

Evaluation of the phospholipid-rich dilute Russell's viper venom assay to monitor oral anticoagulation in patients with lupus anticoagulant.

The International Normalized Ratio (INR) is generally recommended to monitor anticoagulant therapy in patients treated with warfarin. However, there has been concern about the validity of the INR to monitor warfarin therapy in patients with lupus anticoagulant, particularly when there is prolongation of the baseline INR. An alternative approach is to use a chromogenic factor X assay that is not sensitive to lupus anticoagulant. However, this assay is expensive, not widely available, and does not have an established therapeutic range. We hypothesized that the phospholipid-rich dilute Russell viper venom time (prdRVVT), a simple, rapid and inexpensive assay, might be suitable to monitor warfarin therapy in this situation since Russell's viper venom directly activates coagulation factor X while the phospholipid in the reagent reduces or negates any effect of lupus anticoagulant on the assay. We measured the INR, chromogenic factor X, and prdRVVT in 50 patients stabilized on warfarin for at least 6 weeks, 12 of whom had lupus anticoagulant, and 37 patients not taking warfarin, 17 of whom had lupus anticoagulant. Factor X was negatively correlated with INR in anticoagulated patients both in the absence (r = -0.45, P = 0.01) and presence (r = -0.43, P = 0.17) of lupus anticoagulant. The prdRVVT was also strongly correlated with INR in anticoagulated patients without lupus anticoagulant (r = 0.60, P < 0.0001) but there was no correlation in the presence of lupus anticoagulant (r = -0.13, P = 0.68). Our results suggest that the prdRVVT is not suitable for monitoring warfarin therapy in patients with lupus anticoagulant.

A comparative multi-laboratory assessment of three factor VIII/von Willebrand factor concentrates.

Five expert laboratories have participated in a cross-laboratory study to co-evaluate and compare three commercial Factor VIII/von Willebrand factor (VWF) concentrates. A total of nine factor concentrate lots were evaluated, comprising AHF (High Purity) (AHF HP; x3), Biostate (x3) and Humate/Haemate (x3). All laboratories blind tested for FVIII: C, VWF: Ag and VWF: CB, four tested for VWF: RCo, and one performed VWF: Multimers. The study yielded inter-laboratory CVs for VWF: Ag and FVIII:C around 10-15%, and for VWF:CB and VWF:RCo around 20%, significantly lower than those of previous multi-laboratory surveys. All three lots of AHF HP contained in the vicinity of 25 U/ml FVIII:C, around 60-75 U/ml of VWF:Ag, but only 30-45 U/ml of VWF:CB and 40-50 U/ml of VWF:RCo (thus, CB/Ag ratio around 0.5-0.6 and RCo/Ag ratio around 0.6-0.7). Study determined that FVIII: C and VWF: RCo levels were similar to manufacturer assigned levels. Some loss of the high molecular weight (HMW) multimers was observed, together with an intense low molecular weight (LMW) VWF band consistent with some reduction or proteolysis of HMW VWF. All three lots of Humate/Haemate contained in the vicinity of 23-32 U/ml of FVIII:C, 70-105 U/ml of VWF: Ag, 50-90 U/ml of VWF: CB and VWF: RCo (i.e. CB/Ag ratio around 0.6-0.9 and RCo/Ag ratio around 0.6-1.1). Study-determined FVIII: C and VWF: RCo levels were similar to manufacturer-assigned levels. The LMW multimer band seen with AHF HP was also observed with Humate/Haemate. All three lots of Biostate contained in the vicinity of 40-55 U/ml of FVIII:C, 105-170 U/ml of VWF:Ag, 90-150 U/ml of VWF:CB, and 90-135 U/ml of VWF:RCo (i.e. CB/Ag and RCo/Ag ratios around 0.7-1.0). Study-determined FVIII:C levels were similar to manufacturer-assigned levels. The LMW multimer band seen with AHF HP was not observed with Biostate. The defined pattern of increasing CB/ Ag from AHF HP to Humate/Haemate and Biostate was consistently observed in study data from each of the five laboratories. In conclusion, study findings indicate some differences in the retention of functional/ HMW VWF between factor concentrates, and this is expected to have significant implications in terms of clinical efficacy for therapy in VWD.