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Immune thrombocytopenia (ITP) is a diagnosis of exclusion that can resemble other thrombocytopenic disorders.To develop a clinical prediction model (CPM) for the diagnosis of ITP to aid hematogists in investigating patients presenting with undifferentiated thrombocytopenia.We designed a CPM for ITP diagnosis at the time of the initial hematology consultation using penalized logistic regression based on data from patients with thrombocytopenia enrolled in the McMaster ITP registry (n = 523) called the Predict-ITP Tool. The case definition for ITP was a platelet count less than 100 × 10The final model included the following variables: (1) platelet count variability (based on three or more platelet count values), (2) lowest platelet count value, (3) maximum mean platelet volume, and (4) history of major bleeding (defined by the ITP bleeding scale). The optimism-corrected c-statistic was 0.83, the calibration slope was 0.88, and calibration-in-the-large for all performance measures was0.001 with standard error0.001, indicating good discrimination and excellent calibration.The Predict-ITP Tool can estimate the likelihood of ITP for a given patient with thrombocytopenia at the time of the initial hematology consultation. The tool had high predictive accuracy for the diagnosis of ITP.

T-cell clonality testing by T-cell receptor (TCR) gene rearrangement is key to the diagnosis of T-cell lymphoproliferative disorders such as T-cell large granular lymphocytic (T-LGL) leukemia. Benign clonal T-cell expansions, however, are commonly found in patients without identifiable disease, a condition referred to as T-cell clones of uncertain significance (T-CUS). In practice, T-cell clonality testing is performed for a range of reasons and results are often challenging to interpret given the overlap between benign and malignant clonal T-cell proliferations and uncertainties in the management of T-CUS.We conducted a 5-year retrospective cohort study of 211 consecutive patients who underwent PCR-based T-cell clonality testing for suspected T-LGL leukemia at our institution to characterize the use of T-cell clonality testing and its impact on patient management.Overall, 46.4% (n = 98) of individuals tested had a clonal T-cell population identified. Patients with a monoclonal T-cell population were more likely to be older, have rheumatoid arthritis and have higher lymphocyte counts compared to patients with polyclonal populations. The majority of patients eventually diagnosed and treated for T-LGL leukemia had rheumatoid arthritis and lower neutrophil counts compared to untreated patients with monoclonal T-cell populations. A diagnosis of T-LGL leukemia was made in only a minority of patients (n = 48, 22.7%), and only a small proportion were treated (n = 17, 8.1%).Our study suggests that T-cell clonality testing most commonly identifies incidental T-cell clones with only a minority of patients receiving a diagnosis of T-LGL leukemia and fewer requiring active treatment. These finding indicate an opportunity to improve utilization of T-cell clonality testing in clinical practice to better target patients where the results of testing would impact clinical management.

Erythrocytosis, most often measured as an increase in hemoglobin and/or hematocrit, is a common reason for referral to internal medicine and hematology clinics and a rational approach is required to effectively identify patients with polycythemia vera while avoiding over-investigation.We aimed to develop and validate a simple rule to predict JAK2 mutation positivity based on complete blood count parameters to aid in the diagnostic approach to patients referred for elevated hemoglobin.Internal medicine and hematology clinics at an academic tertiary referral center.The JAK2 Prediction Cohort (JAKPOT), a large retrospective cohort (n = 901) of patients evaluated by internal medicine and hematology specialists for elevated hemoglobin.JAK2 mutation analysis was performed in all patients and clinical and laboratory variables were collected. Patients were randomly divided into derivation and validation cohorts. A prediction rule was developed using data from the derivation cohort and tested in the validation cohort.The JAKPOT prediction rule included three variables: (i) red blood cell count6.45×10In patients with elevated hemoglobin, the use of a simple prediction rule helps to accurately identify patients with a low likelihood of having a JAK2 mutation, potentially limiting costly over-investigation in this common referral population.

KEY POINTS A 66-year-old man presented to the emergency department with a 2-week history of progressive weakness and lethargy. Three months before presentation, he had been started on azathioprine therapy for immunoglobulin (Ig) G4-related biliary disease. Comorbidities included hypertension

POINTS CLES Un homme de 66 ans consulte aux urgences pour faiblesse et lethargie progressives depuis 2 semaines. Trois mois auparavant, il avait commence un traitement par azathioprine pour une maladie des voies biliaires associee aux IgG4 (immunoglobulines G4). Il etait atteint des comorbidit

Background: Patients with immune thrombocytopenia are at risk of bleeding during surgery, and intravenous immunoglobulin is commonly used to increase the platelet count. We aimed to establish whether perioperative eltrombopag was non-inferior to intravenous immunoglobulin. Methods: We did a randomised, open-label trial in eight academic hospitals in Canada. Patients were aged at least 18 years, with primary or secondary immune thrombocytopenia and platelet counts less than 100 × 109 cells per L before major surgery or less than 50 × 109 cells per L before minor surgery. Previous intravenous immunoglobulin within 2 weeks or thrombopoietin receptor agonists within 4 weeks before randomisation were not permitted. Patients were randomly assigned to receive oral daily eltrombopag 50 mg from 21 days preoperatively to postoperative day 7 or intravenous immunoglobulin 1 g/kg or 2 g/kg 7 days before surgery. Eltrombopag dose adjustments were allowed weekly based on platelet counts. The randomisation sequence was generated by a computerised random number generator, concealed and stratified by centre and surgery type (major or minor). The central study statistician was masked to treatment allocation. The primary outcome was achievement of perioperative platelet count targets (90 × 109 cells per L before major surgery or 45 × 109 cells per L before minor surgery) without rescue treatment. We did intention-to-treat and per-protocol analyses using an absolute non-inferiority margin of –10%. This trial is registered with ClinicalTrials.gov, NCT01621204. Findings: Between June 5, 2013, and March 7, 2019, 92 patients with immune thrombocytopenia were screened, of whom 74 (80%) were randomly assigned: 38 to eltrombopag and 36 to intravenous immunoglobulin. Median follow-up was 50 days (IQR 49–55). By intention-to-treat analysis, perioperative platelet targets were achieved for 30 (79%) of 38 patients assigned to eltrombopag and 22 (61%) of 36 patients assigned to intravenous immunoglobulin (absolute risk difference 17·8%, one-sided lower limit of the 95% CI 0·4%; pnon-inferiority=0·005). In the per-protocol analysis, perioperative platelet targets were achieved for 29 (78%) of 37 patients in the eltrombopag group and 20 (63%) of 32 in the intravenous immunoglobulin group (absolute risk difference 15·9%, one-sided lower limit of the 95% CI –2·1%; pnon-inferiority=0·009). Two serious adverse events occurred in the eltrombopag group: one treatment-related pulmonary embolism and one vertigo. Five serious adverse events occurred in the intravenous immunoglobulin group (atrial fibrillation, pancreatitis, vulvar pain, chest tube malfunction and conversion to open splenectomy); all were related to complications of surgery. No treatment-related deaths occurred. Interpretation: Eltrombopag is an effective alternative to intravenous immunoglobulin for perioperative treatment of immune thrombocytopenia. However, treatment with eltrombopag might increase risk of thrombosis. The decision to choose one treatment over the other will depend on patient preference, resource limitations, cost, and individual risk profiles. Funding: GlaxoSmithKline and Novartis.

Next-generation sequencing (NGS) increasingly influences diagnosis, prognosis and management of myelodysplastic syndrome (MDS). In addition to marrow morphology and flow cytometry, our institution performs cytogenetics (CG) and NGS-based testing routinely in patients with suspected MDS. We evaluated the relative value of NGS in the assessment of patients with suspected MDS. We initially compared the diagnostic and prognostic information derived from CG and NGS in 134 patients. NGS enhanced the diagnostic yield compared to CG for clonal myeloid disorders (sensitivity 77% vs. 42·2%; specificity 90·2% vs. 78%; positive predictive value 92·8% vs. 76%; and negative predictive value 70·8% vs. 45·5%). The identification of poor prognosis mutations by NGS altered risk category in 27/39 (69·2%) patients with MDS with good/intermediate risk CG. Subsequently, we prospectively evaluated 70 patients with suspected MDS using an 'NGS-first approach' with CG restricted to samples with morphological abnormalities. We rarely identified mutations or CG abnormalities in patients without dysplastic features. NGS has a superior diagnostic performance compared to CG in patients with suspected MDS. We estimate that by using an 'NGS-first approach' we could reduce karyotyping by approximately 30%.

The use of molecular genetic biomarkers is rapidly advancing to aid diagnosis, prognosis, and clinical management of hematological disorders. We have implemented a next-generation sequencing (NGS) assay for detection of genetic variants and fusions as a frontline test for patients suspected with myeloid malignancy. In this study, we summarize the findings and assess the clinical impact in the first 1613 patients tested.All patients were assessed using NGS based Oncomine Myeloid Research Assay (ThermoFisher) including 40 genes (17 full genes and 23 genes with clinically relevant "hotspot" regions), along with a panel of 29 fusion driver genes (including over fusion 600 partners).Among 1613 patients with suspected myeloid malignancy, 43% patients harbored at least one clinically relevant variant: 91% (90/100) in acute myeloid leukemia patients, 71.7% (160/223) in myelodysplastic syndrome (MDS), 77.5% (308/397) in myeloproliferative neoplasm (MPN), 83% (34/41) in MPN/MDS, and 100% (40/40) in chronic myeloid leukemia patients. Comparison of NGS and cytogenetics results revealed a high degree of concordance in gene fusion detection.Our findings demonstrate clinical utility and feasibility of integrating a NGS-based gene mutation and fusion testing assay as a frontline diagnostic test in a large reported cohort of patients with suspected myeloid malignancy, in a clinical laboratory setting. Overlap with cytogenetic test results provides opportunity for testing reduction and streamlining.

Introduction In most laboratories, next generation sequencing (NGS) has been added without consideration for redundancy compared to conventional cytogenetics (CG). We tested a streamlined approach to genomic testing in patients with suspected myeloid and plasma cell neoplasms using next generation sequencing ("NGS first") as the primary testing modality and limiting cytogenetics (CG) to samples with morphologic abnormalities in the marrow aspirate. Methods Based on morphologic interpretation of bone marrow aspirate and flow cytometry, samples were triaged into four groups: (a) Samples with dysplasia or excess blasts had both NGS and karyotyping; (b) Samples without excess blasts or dysplasia had NGS only; (c) Repeat samples with previous NGS and/or CG studies were not retested; (d) Samples for suspected myeloma with less than 5% plasma cell had CG testing cancelled. Results Seven hundred eleven adult bone marrow (BM) samples met the study criteria. The NGS first algorithm eliminated CG testing in 229/303 (75.6%) of patients, primarily by reducing repeat testing. Potential cost avoided was approximately $124 000 per annum. Hematologists overruled the triage comment in only 11/303 (3.6%) cases requesting CG testing for a specific indication. Conclusions Utilizing NGS as the primary genomic testing modality NGS was feasible and well accepted, reducing over three quarters of all CG requests and improving the financial case for adoption of NGS. Key factors for the success of this study were collaboration of clinical and genomic diagnostic teams in developing the algorithm, rapid turnaround time for BM interpretation for triage, and communication between laboratories.

OBJECTIVES The diagnosis of hematologic malignancies integrates multiple diagnostic and clinical disciplines. Historically, targeted (single-analyte) genetic testing has been used as reflex to initial prescreening by other diagnostic modalities including flow cytometry, anatomic pathology, and clinical cytogenetics. Given the wide range of mutations associated with hematologic malignancies a DNA/RNA-based NGS panel can provide a more effective and economical approach to comprehensive testing of patients as an initial, tier-1 screen. METHODS Using a cohort of 380 patients, we performed clinical validation of a gene panel designed to assess 40 genes (DNA), and 29 fusion driver genes with over 600 gene fusion partners (RNA), including sample exchange data across three clinical laboratories, and correlation with cytogenetic testing results. RESULTS The clinical validation of this technology demonstrated that its accuracy, sensitivity, and specificity are comparable to the majority of targeted single-gene approaches, while assessment of the initial patient cohort data demonstrated a high diagnostic yield of 50.5%. CONCLUSIONS Implementation of a tier-1 NGS-based protocol for gene panel screening provides a comprehensive alternative to targeted molecular testing in patients with suspected hematologic malignancies, with increased diagnostic yield, scalability, reproducibility, and cost effectiveness, making it ideally suited for implementation in clinical laboratories.

Eltrombopag has been shown to be noninferior to intravenous immunoglobulin (IVIG) for improving perioperative platelet counts in patients with immune thrombocytopenia (ITP) in a randomized trial; thus, cost is an important factor for treatment and policy decisions. We used patient-level data from the trial to conduct a cost-effectiveness analysis comparing perioperative eltrombopag 50 mg daily starting dose, with IVIG 1 or 2 g/kg (according to local practice) from a Canadian public health care payer’s perspective over the observation period, from preoperative day 21 to postoperative day 28. Resource utilization data were obtained from the trial data (eltrombopag, n = 38; IVIG, n = 36), and unit costs were collected from the Ontario Schedule of Benefits, Ontario Drug Formulary, and secondary sources. All costs were adjusted to 2020 Canadian dollars. We calculated the incremental cost per patient for all patients randomized. Uncertainty was addressed using nonparametric bootstrapping. The use of perioperative eltrombopag for patients with ITP resulted in a cost-saving of $413 Canadian per patient. Compared with IVIG, the probability of eltrombopag being cost effective was 70% even with no willingness to pay. In a sensitivity analysis based on IVIG dose, we found that with the higher dose of IVIG (2 g/kg), eltrombopag saved $2,714 per patient, whereas with the lower dose of IVIG (1 g/kg), eltrombopag had a higher mean cost of $562 per patient. In summary, based on data from the randomized trial that demonstrated noninferiority, the use of eltrombopag for the management of ITP in the perioperative setting was less costly than IVIG.

Four-factor prothrombin complex concentrate (4F-PCC) is widely used for urgent reversal of anticoagulation with warfarin, but the optimal 4F-PCC dosing approach is unknown. Herein, we sought to determine the efficacy of a novel fixed, weight-based dosing nomogram.We retrospectively studied consecutive adult patients receiving fixed, weight-based 4F-PCC dosing for warfarin reversal between 30 April 2009 and 31 December 2010. The primary outcome was reversal of warfarin anticoagulation, defined as INR ≤1.5 within 6 h. Secondary outcome was the occurrence of thromboembolic events.A total of 227 patients (56% male), with a median age of 74 years and a median weight of 76kg were evaluated. The most common indications for 4F-PCC were active bleeding (37.4%: 12.7% intracranial, 12.3% gastrointestinal, 4.0% trauma, 8.4% other), reversal for a procedure (22.0%), reversal for surgery (29.5%) or other (11.1%). 66.1% of patients achieved an INR ≤1.5 within 6 h of 4F-PCC administration. 95.0% (57/60) of patients completed a planned procedure and 95.7% (67/70) of patients completed a planned surgery. The median baseline INR was 2.9 (1.5-10) and decreased significantly to a median of 1.3 (1.0-3.7) (Fixed, weight-based dosing of 4F-PCC is effective for reversing warfarin anticoagulation in patients with a pre-dosing INR ≤ 4.5.

Key Clinical Message Granular acute lymphoblastic leukemia (ALL) is a rare variant of the disease that is associated with a lower remission rate to standard induction chemotherapy. Flow immunophenotyping, cytogenetics, and molecular diagnostics should be utilized to confirm the diagnosis of ALL versus acute myeloid leukemia (AML) in order to provide appropriate management.

Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease of the central nervous system that most often affects immunocompromised individuals. It is caused by the reactivation of the John Cunningham virus (JCV), which is found in latent form in the majority of adults. We describe a 59-year-old man with multiple myeloma who developed severe neurological deficits during treatment with ixazomib-based chemotherapy. A diagnosis of PML was established with gadolinium-enhanced magnetic resonance imaging (MRI) and by detection of JCV in the cerebrospinal fluid. Despite cessation of chemotherapy and treatment with mirtazapine, he had an inexorable neurological decline and died two months after presenting to hospital. Multiple myeloma and its treatments can predispose patients to opportunistic infections including PML. Although there have been case reports of PML in patients with multiple myeloma treated with bortezomib (a different proteosome inhibitor), this is, to our knowledge, the first documented case of PML in a patient treated with a regimen that includes ixazomib.

We present the case of a novel β-globin gene variant associated with early-onset transfusion-dependent anemia compatible with a β-thalassemia major (β-TM) phenotype in a patient of British descent....

Background: Since the identification of JAK2 mutations in polycythemia vera (PV) in 2005 (Kralovics et al., NEJM 2005), molecular testing of JAK2 in patients with erythrocytosis has become part of routine clinical practice. We hypothesized that changes in the World Health Organization (WHO) diagnostic criteria for PV in 2016, which lowered the hemoglobin threshold to >165 g/L for men and >160 g/L for women, may have resulted in increased molecular testing. This study examines changing patterns of utilization of molecular diagnostics in patients referred for erythrocytosis at a tertiary care center. Methods: We examined all patients with erythrocytosis who underwent JAK2 testing, which included testing for JAK2 V617F with PCR between 2015 and 2017, and JAK2 V617F and exon 12 mutations with Next-Generation Sequencing (NGS) between 2018 and 2020 at London Health Sciences Centre in Ontario, Canada. We performed a retrospective chart review to extract laboratory and clinical data, including information on medical comorbidities and medications, with a focus on known secondary causes of erythrocytosis. Results: A total of 668 patients with erythrocytosis underwent JAK2 testing at our institution between August 1, 2015 and December 31, 2020. There was an overall increase in testing over the five-year study period, with a decline in the positive detection rate: 8/29 (28%) in 2015, 15/94 (16%) in 2016, 15/100 (15%) in 2017, 19/136 (14%) in 2018, 17/162 (10%) in 2019, and 14/147 (10%) in 2020 (Figure 1). The average hemoglobin levels in patients with erythrocytosis who underwent testing remained similar across all years (range 170-173 g/L for women, 179-181 g/L for men). In our cohort, there was a high proportion of patients with known or suspected secondary causes of erythrocytosis who underwent molecular testing. Between 2018 and 2020, 324/445 (73%) of patients who underwent molecular testing had either chronic obstructive pulmonary disease, obstructive sleep apnea, other hypoxic lung disease, smoking history, erythropoietin-secreting tumor, or potential drug-induced erythrocytosis. Specifically, we observed an increase in proportion of patients who underwent molecular testing on sodium-glucose cotransporter-2 (SGLT-2) inhibitors, a known secondary cause of erythrocytosis, with 15/136 (11%) in 2018, 17/162 (10%) in 2019, and 25/147 (17%) in 2020. In contrast, the proportion of patients on testosterone was relatively constant at 15/136 (11%) in 2018, 11/162 (6.8%) in 2019, and 11/147 (7.5%) in 2020. Conclusion: This study revealed that a high proportion of patients with known or suspected secondary causes of erythrocytosis underwent JAK2 testing, resulting in increase in molecular testing over time and a decline in positive detection rate. In particular, we observed a number of patients on SGLT-2 inhibitors who had investigation, suggesting that this class of medications may be an underrecognized cause of drug-induced erythrocytosis (Chin-Yee et al., CMAJ 2020). Our findings underscore the importance of careful medical history and medication review to support more judicious use of molecular testing. Similarity in average hemoglobin levels across the five-year study period suggests that other factors, such as increased availability of 'routine' molecular testing, rather than changes in the WHO diagnostic criteria may explain increases in JAK2 testing. Our study indicates a need to develop an effective clinical prediction rule for JAK2 positivity to better risk stratify patients with suspected PV based on clinical and laboratory parameters to optimize utilization of molecular diagnostics. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Background: The widespread availability of molecular testing for JAK2 mutations has facilitated the diagnosis of polycythemia vera (PV) but also raises the concern of test overutilization in patients referred for elevated hemoglobin. At our institution, we have observed increased molecular testing in these patients with declining rates of JAK2 mutation positivity, suggesting that a prediction rule could be useful to guide such testing. In this study, we report the derivation and validation of a simple rule using complete blood count (CBC) parameters to predict the likelihood of having a JAK2 mutation in patients referred for elevated hemoglobin. Methods: We examined all patients with elevated hemoglobin (≥160 g/L for women, or ≥165 g/L for men), who underwent JAK2 mutation testing using the Next-Generation Sequencing (NGS)-based Oncomine Myeloid Research Assay (ThermoFisher Scientific, MA, USA), between 2018 and 2021 at the London Health Sciences Centre in Ontario, Canada. We extracted data including age and sex as well as CBC parameters at the time of testing, including hemoglobin, hematocrit, erythrocytes, leukocytes, neutrophils, platelets and mean corpuscular volume. All CBCs were performed on a Sysmex XN Analyzer (Sysmex Corporation, Japan). In the derivation cohort, JAK2-positive and -negative groups were compared using Student's t-tests or c 2 tests, as appropriate. We dichotomized potentially significant continuous variables at an optimal cut-off point using receiving operating characteristic curves. Potentially significant predictors were evaluated using multiple variable stepwise logistic regression analysis with JAK2 positivity as the dependent variable. The model was evaluated using Hosmer-Lemeshow tests and pseudo-R2 measures. A dichotomous score was derived based on the presence or absence of significant variables and subsequently evaluated and internally validated using logistic regression and c 2 tests using non-parametric bootstrapping with 1000 samples. The model was subsequently validated in the second cohort. Results: The derivation cohort included 308 patients tested between January 9, 2018 and December 19, 2019, and the validation cohort included 223 patients tested between January 7, 2020 and May 12, 2021. The characteristics of both cohorts are shown in Table 1. The final model included platelets above the upper quintile (308 × 10 9/L) and erythrocytes above the upper quartile (6.17 × 10 12/L) and a score of one was assigned to patients with either of these characteristics. The odds ratio for JAK2 positivity in patients with a score of 1 was 14.6 (95% CI 5.5-38.8) compared to those with a score of 0. The model had a sensitivity of 87.8% and a negative predictive value of 97.4% in the derivation cohort, and of 100% for both in the validation cohort. The percentage of JAK2 positive patients in patients with a score of 1 was 28%. The percent of false negatives was 2.6% (95% CI 1.1-6.0) and 0 (95% CI 0-2.8) in the derivation and validation cohorts, respectively. The use of this rule to guide molecular testing would have resulted in approximately 60% fewer tests. Conclusion: We developed and validated a simple rule to predict the likelihood of JAK2 mutation positivity in patients with a hemoglobin of 160 or higher, based on CBC parameters with a high negative predictive value (Figure 1). If implemented, this prediction rule could result in a significant reduction in molecular testing avoiding 60% or approximately 100 tests per year at our institution. This approach would be particularly beneficial for broader health system management of hematological malignancies, facilitating the reallocation of resources to emerging higher-yield molecular diagnostic investigation (Kawata et al., BJH 2021). Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Background: JAK2 V617F and exon 12 mutations are the characteristic driver mutations in polycythemia vera (PV), identified in more than 95% of patients. In addition, other genetic mutations have previously been described in JAK2-positive PV that appear to have prognostic significance (Tefferi et al., Blood 2016). The incidence of other driver mutations in unselected patients referred for elevated hemoglobin is less well studied. This study aims to characterize the genetic mutational landscape in a real-world population of patients referred for elevated hemoglobin using a targeted Next-Generation Sequencing (NGS)-based assay. Methods: We reviewed all patients referred for elevated hemoglobin levels (>160 g/L in females or >165 g/L in males) between 2018 and 2020 to hematology clinics at London Health Sciences Centre in Southwestern Ontario, Canada who underwent testing for genetic variants using the NGS-based Oncomine Myeloid Research Assay (ThermoFisher Scientific, MA, USA). This assay targets 40 key genes with diagnostic and prognostic implications in several myeloid malignancies (17 full genes and 23 genes with clinically relevant "hotspot" regions) and a panel of 29 fusion driver genes (>600 fusion partners). Patient demographics, laboratory data and final diagnosis were extracted from the electronic medical record. For all patients with genetic mutations, clinical diagnosis was confirmed by three independent reviewers. Results: A total of 529 patients underwent genetic testing for elevated hemoglobin levels: 389 (73.5%) were males (mean age 58; range 18-95) and 140 (26.5%) were female (mean age 60; range 24-85). JAK2 mutations were detected in 10.9% (58/529) of patients and a diagnosis of PV was confirmed. The majority of JAK2-mutated PV patients (n=57) were positive for JAK2 V617F, while one patient had an exon 12 mutation. Additional single myeloid mutations were detected in 34.5% (20/58) of JAK2-positive patients and involved the following genes: TET2 (11; 19%), DNMT3A (2; 3.4%), ASXL1 (2; 3.4%), SRSF2 (2; 3.4%), BCOR (1; 1.7%), TP53 (1; 1.7%) and ZRSR2 (1; 1.7%) (Figure 1A). JAK2 mutations were not detected in 89.0% (471/529) of our cohort. A diagnosis of PV was confirmed in 2 JAK2-negative patients based on clinical features and myeloid mutations were detected in both: SRSF2 and TET2 gene mutations in 1 patient and SRSF2, IDH2, ASXL1 gene mutations in the other patient. Three JAK2-negative patients tested positive for the BCR-ABL fusion and were diagnosed with chronic myeloid leukemia. The remaining 466 JAK2-negative patients were diagnosed with secondary erythrocytosis and myeloid mutations were found in 6% (28/466) of these cases. Mutations were detected in DNMT3A (12; 2.6%), TET2 (5; 1.1%), ASXL1 (5; 1.1%), TP53 (2; 0.4%), NF1 (2; 0.4%), KIT (1; 0.2%), U2AF1 (1; 0.2%) (Figure 1B). All patients with JAK2-negative secondary erythrocytosis had only one myeloid gene mutation detected. Conclusion: Additional myeloid mutations other than JAK2 mutations are frequently identified in patients referred for erythrocytosis, with the highest frequencies observed in the TET2, DNMT3A and ASXL1 genes. The spectrum of myeloid mutations and overall incidence in JAK2-negative patients with secondary erythrocytosis is similar to the reported incidence of Clonal Hematopoiesis of Indeterminate Potential (CHIP) (Jaiswal et al., NEJM 2014), and suggests that these may represent incidental age-related mutations. By contrast, among the JAK2-positive patients, 34.5% had at least one additional myeloid mutation supporting a pathogenic role in these patients with myeloproliferative neoplasms. While concomitant myeloid mutations in patients with PV are well-described, further research is required to elucidate the significance of variants identified in JAK2-negative patients classified as secondary erythrocytosis in order to determine whether these mutations contribute to clinical phenotype or represent background CHIP. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Introduction: Ibrutinib, an oral Bruton Kinase inhibitor, is a highly effective treatment for patients with chronic lymphocytic leukemia (CLL). Previous studies reported an increased risk of bleeding due to impaired platelet function. Patients with CLL experience significant thrombocytopenia, which increases their risk for bleeding. This population was excluded from major trials and data is lacking to inform management in this setting. Methods: This is a single center retrospective study of all adult patients with CLL who received single agent ibrutinib in London, Ontario, Canada between January 2014 to December 2020. The primary objective was to investigate the risk of major bleeding associated with thrombocytopenia. Secondary objective was to investigate potential predictors of bleeding. Bleeding events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) grading system. A major bleed was defined as CTCAE grade 3 or higher as well as bleeding in the central nervous system. To assess the effect of independent variables on the outcome of bleeding, univariate analysis using chi square and t-tests was performed. Multivariate analysis was then preformed with the variables that were significant (p Results: A total of 170 patients were included in this study. There were 54 bleeding events documented in 42 patients (24.7 %) of which 19(35 %) were major bleeding occurring in 17 patients. Median time to major bleeding was 2.4 months. Of the patients with major bleeding, 4(21%) were on anticoagulation, 2(10%) were on antiplatelet and 2(10%) were on combined anticoagulation and antiplatelet. There were 8 central nervous system (CNS) bleeding and 2 of them died. The mean platelet (PLT) nadir, defined as lowest PLT count at any point during ibrutinib treatment, was 73 x 10 9/Lin patients with major bleeding compared to 116 x 10 9/L in patients with minor and 91 x 10 9/L in patients with no bleeding events. On the univariate analysis, when compared patients with major bleeding to patients with no bleeding, potential predictors of major bleeding included PLT nadir (p=0.09), haemoglobin (Hb) < 100 g/L at ibrutinib initiation (p=0.027) and anticoagulation (p=0.009). When compared patients with major bleeding to patients with minor or no bleeding, potential predictors of major bleeding included PLT nadir (p=0.045), Hb To confirm the significance of these variables, multivariate analysis was performed. When compared patients with major bleeding to patients with no bleeding, PLT nadir (OR= 0.9, p=0.008) and anticoagulation (OR=4.02, p=0.001) were confirmed to be the potential predictors of major bleeding. When compared patients with major bleeding to patients with minor or no bleeding, PLT nadir (OR=0.9 p=0.005) and Hb Conclusions: Although not common, Ibrutinib is associated with increased risk of bleeding and identifying high risk patients is essential to prevent major bleeding events. This retrospective Canadian study was done with the primary objective to assess the association between PLT count and major bleeding in patients on ibrutinib for treatment of CLL. In this analysis patients with major bleeding tend to have lower PLT counts compared to patients with minor or no bleeding, with mean PLT nadir of 73x 10 9/L. However, grade 3 thrombocytopenia (PLT nadir Figure 1 Figure 1. Disclosures Louzada: Amgen: Honoraria; Pfizer: Honoraria; Celgene: Honoraria; Janssen: Honoraria. Lam: AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Hoffmann-La Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; SeaGen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Meyers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Beigene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees. Phua: Amgen: Honoraria; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria; NovoNordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria.

Pathogen inactivation of platelet concentrates reduces the risk for blood-borne infections. However, its effect on platelet function and hemostatic efficacy of transfusion is unclear. We conducted a randomized noninferiority trial comparing the efficacy of pathogen-inactivated platelets using riboflavin and UV B illumination technology (intervention) compared with standard plasma-stored platelets (control) for the prevention of bleeding in patients with hematologic malignancies and thrombocytopenia. The primary outcome parameter was the proportion of transfusion-treatment periods in which the patient had grade 2 or higher bleeding, as defined by World Health Organization criteria. Between November 2010 and April 2016, 469 unique patients were randomized to 567 transfusion-treatment periods (283 in the control arm, 284 in the intervention arm). There was a 3% absolute difference in grade 2 or higher bleeding in the intention-to-treat analysis: 51% of the transfusion-treatment periods in the control arm and 54% in the intervention arm (95% confidence interval [CI], -6 to 11; P=.012 for noninferiority). However, in the per-protocol analysis, the difference in grade 2 or higher bleeding was 8%: 44% in the control arm and 52% in the intervention arm (95% CI22 to 18; P=.19 for noninferiority). Transfusion increment parameters were similar to 50% lower in the intervention arm. There was no difference in the proportion of patients developing HLA class I alloantibodies. In conclusion, the noninferiority criterion for pathogen-inactivated platelets was met in the intention-to-treat analysis. This finding was not demonstrated in the per-protocol analysis. This trial was registered at The Netherlands National Trial Registry as # NTR2106 and at www. clinicaltrials. gov as # NCT02783313.

Background: Patients with immune thrombocytopenia (ITP) are at risk of bleeding during surgery. Intravenous immune globulin (IVIG) is a blood product that is commonly used to increase platelet counts before surgery or invasive procedures for patients with ITP; however, eltrombopag, an oral thrombopoietin receptor agonist, may be an effective alternative. Methods: We conducted a multicenter randomised trial to determine whether eltrombopag was non-inferior to IVIG for the achievement of perioperative platelet count targets without the use of rescue treatment. We did an intention to treat and per-protocol analysis using an absolute non-inferiority margin of -10%. Secondary endpoints were thrombosis, bleeding, adverse events and treatment satisfaction. We enrolled 74 patients with ITP who had a planned major or minor surgery and with a platelet count below 100 x109/L or 50 x109/L respectively. Patients were randomised to receive oral daily eltrombopag from 21 days preoperatively, or IVIG (1 or 2g per kg) seven days preoperatively. Findings: By intention to treat, perioperative platelet targets were achieved by 30 of 38 patients (78·9%) assigned to eltrombopag and 22 of 36 patients (61·1%) assigned to IVIG (absolute difference, 17·8%; one-sided lower limit of the 95% confidence interval, 0·4%; p=0·005 for non-inferiority). Results were similar for patients who completed the protocol. One patient in the eltrombopag group developed a pulmonary embolism 14 days after minor surgery, and one patient in the IVIG group developed a distal deep vein thrombosis 30 days after major surgery. There was no difference in bleeding or adverse events. Patients reported higher treatment satisfaction with eltrombopag. Interpretation: Eltrombopag was no worse than IVIG for the achievement of platelet count targets around the time of surgery for patients with ITP. This population may be at increased risk of thrombosis. Trial Registration: www.clinicaltrials.gov number as NCT01621204. Funding Statement: This trial was funded by GlaxoSmithKline and Novartis. Declaration of Interests: N.M.H., R.J.C., M.B., J.K., A.T., M.S., M.W., P.V., J.C., N.L., S.L., and J.G.K. report no competing financial interests. D.M.A. reports grants from GlaxoSmithKline and Novartis during the conduct of the study; grants and/or personal fees from Novartis, Amgen, Bristol Myers Squibb, UCB, Principia, and Rigel outside the submitted work. C.H. reports personal fees from Novartis, Amgen, and GSK, outside the submitted work. E.J. reports personal fees from Novartis, outside the submitted work. M.S. reports personal fees from Novartis, outside the submitted work. Y.L. reports grants from Novartis during the conduct of the study, and other fees from Pfizer, outside the submitted work. L.L. reports personal fees from Novartis during the conduct of the study. S.A. reports grants from Novartis NL during the conduct of the study; grants from Amgen, outside the submitted work. W.L. reports personal fees from Novartis, outside the submitted work. Ethics Approval Statement: The trial was approved by the research ethics boards at each participating center. The study was conducted in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines.

BACKGROUND The optimal method of providing transfusion medicine (TM) education has not been determined. Transfusion Camp was established in 2012 at the University of Toronto as a centrally delivered TM education program for postgraduate trainees. The impact of Transfusion Camp on knowledge, attitudes, and self-reported behavior was evaluated. METHODS Didactic lectures (delivered locally, by webinar, or recorded) and locally facilitated team-based learning seminars were delivered over 5 days during the academic year to 8 sites: 7 in Canada and 1 in the United Kingdom. Knowledge assessment using a validated 20-question multiple-choice exam was conducted before and after Transfusion Camp. Attitudes and self-reported behavior were collected through a survey. RESULTS Over 2 academic years (July 2016 to June 2018), 390 trainees from 16 different specialties (predominantly anesthesia, 41%; hematology, 14%; and critical care, 7%) attended at least 1 day of Transfusion Camp. The mean pretest score was 10.3 of 20 (±2.9; n = 286) compared with posttest score of 13.0 (±2.8; n = 194; p < 0.0001). Lower pretest score and greater attendance (4-5 days compared with 1-3 days) were associated with larger improvement in posttest score; delivery format, specialty, and postgraduate year were not. Trainees reported an improvement in self-rated abilities to manage TM scenarios; 95% rated TM knowledge as very or extremely important in providing patient care; and 81% indicated that they had applied learning from Transfusion Camp into clinical practice. CONCLUSIONS Transfusion Camp increased TM knowledge, fostered a positive attitude toward TM, and enabled a self-reported positive impact on transfusion practice in postgraduate trainees. It is a novel and scalable approach to delivering TM education.

The duration of red blood cell (RBC) storage may have a negative impact on endothelial nitric oxide bioavailability. We tested the hypothesis that transfused fresh blood will have a more favorable effect on microvascular endothelial function as compared to older standard issue blood.Participants requiring chronic RBC transfusions were enrolled in a crossover design study to receive fresh (7 days of storage) or standard (up to 42 days of storage) blood on 2 separate visits. Endothelial function was assessed by reactive hyperemia peripheral arterial tonometry that was measured before and after transfusions. For each participant, the difference between endothelial function pretransfusion and posttransfusion was assessed in relation to blood storage time.Twenty-one patients (71 ± 16 years, 52% females) were enrolled. Mean age of fresh blood was 5.5 days (±1.0), and that of standard blood was 24.5 days (±7.9 days). The pretransfusion hemoglobin was 83.1 ± 2.5 g/L; and posttransfusion, 98.9 ± 2.6 g/L. An average of 2 U of packed RBCs was transfused. Microvascular endothelial function decreased more frequently after transfusion of standard blood compared to fresh blood. Standard issue blood transfusion was associated with decrease in reactive hyperemia peripheral arterial tonometry index (-0.25 ± 0.63) compared to fresh blood (+0.03 ± 0.49); P = .026.Transfusions of standard issue blood are associated with less favorable effect on microvascular endothelial function as compared to fresh blood.

BACKGROUND The impact of age of red blood cells on health-related quality of life (HRQL) in patients who require chronic transfusions is not known. We assessed this using n-of-1 trials in patient populations where large randomized trials have not been done to date. STUDY DESIGN AND METHODS Chronically transfusion-dependent adult patients were randomly assigned over time to four fresh (

Introduction: Unexplained erythrocytosis is a common reason for consultation in hematology. Identification of JAK2V617F mutation has facilitated the diagnosis of Polycythemia Vera (PV), but a proportion of patients without clear secondary causes for erythrocytosis remain undiagnosed or presumptively diagnosed with an either Exon 12 mutation or JAK2 negative PV. Since 2005, our institution has been performing JAK2V617F testing by PCR. In 2018 we switched to an NGS panel which includes JAK2/exon 12 and 40 other genes implicated in myeloid malignancies. We reviewed all previously diagnosed PV who had NGS myeloid panel performed to determine whether patients with a clinical diagnosis of JAK2 negative PV had other myeloid mutations that might explain their erythrocytosis and alter their management. Methods: We identified all cases with clinically suspected PV or confirmed JAK2 mutated PV who went on to have had NGS testing performed between January 2018 and February 2019 at London Health Sciences Centre, a tertiary care center servicing a population of approximately 2.5 million in Ontario, Canada. The Oncomine Myeloid NGS panel (Thermo-Fisher, MA, USA) examines DNA sequence variants in 40 genes (17 full genes and 23 hotspot genes) along with an RNA-based panel of 29 fusion driver genes and their over 600 fusion partners. Diagnosis was based on the WHO 2016 Classification of Tumours of Haematopoietic and Lymphoid Tissues. The clinical impact was assessed from retrospective review of electronic medical record to determine whether there was a diagnostic or management impact. Results: A total of 143 patients followed for PV or unexplained erythrocytosis had NGS testing during the study period. Of those, 137/143 (95.8%) patients had previous JAK2V617F PCR tested and 48/137 (35%) were identified with JAK2V617F mutation. Of the 48 patients with previous JAK2V617F PCR detected, NGS confirmed JAK2 mutation in 40/48 (83.3%) with additional non-JAK2 mutations in 17/40 (42.5%) patients. Of note 8/48 (16.7%) patients previously detected JAK2V617F by PCR had undetectable JAK2 mutation when repeat testing was performed by NGS. Of those 89/137 (65%) patients with previous JAK2V617F PCR negative result, NGS revealed JAK2 exon 12 mutation in 3/89 (3.4%) patients and JAK2V617F/JAK2L611V mutations in 1/89 (1.1%) patient resulting in diagnosis as PV, whereas non-JAK2 mutations in 6/89 (6.7%) patients. No MPL or CALR positive cases were identified in this cohort. Remaining 79/89 (88.8%) had no mutations identified (Figure1) and in this group, 13/79 (16.5%) patients were discharged from hematology clinic, 7/79 (8.9%) had therapies such as phlebotomy, aspirin or hydroxyurea stopped or reduced, whereas 2/79 (2.5%) patients had further evaluation or testing for unexplained erythrocytosis. (Table 1) Conclusions: In the unexplained erythrocytosis JAK2V617F PCR negative group, JAK2exon 12 mutation was identified in 3.4% in keeping with known incidence of this mutation. Some previously positive PCR JAK2V617F mutation were not identified by NGS panel (16%) which may reflect changes in clone size either with time or therapy or inherent differences in assay sensitivity (2.5% mutational alleles for NGS versus 0.1% for PCR). Lack of identifiable myeloid mutation and clonal hematopoiesis by NGS testing influenced clinical management. Specifically, mutation negative patients were more likely assigned to non-MPN group and called secondary erythrocytosis which resulted in reducing interventions. Non-JAK2 mutations occurred in more than 1/3 of previously identified JAK2 positive PCR tested PV. The clinical impact of most these mutations is uncertain and requires longer follow up. Disclosures No relevant conflicts of interest to declare.

We thank Dr. Mithoowani and colleagues for their excellent review on the investigation and management of erythrocytosis,[1][1] which provides a comprehensive overview and approach to a common presentation encountered by hematologists and general practitioners. One additional drug-associated cause

Background The Bridging ITP Trial is an open-label randomized trial designed to compare the oral thrombopoietin receptor agonist eltrombopag and intravenous immune globulin (IVIG) for patients with immune thrombocytopaenia (ITP) who require an increase in platelet count before elective surgery. Here, we report the study methods and rationale. Methods We designed a multi-centre, non-inferiority randomized trial comparing daily oral eltrombopag starting 3 weeks pre-operatively, and IVIG administered 1 week pre-operatively for patients with ITP requiring a platelet count increase prior to surgery. Starting dose of eltrombopag is 50 mg daily with a weekly pre-operative dose titration schedule, and treatment is continued for 1 week after surgical haemostasis is achieved. IVIG is administered at a dose of 1 to 2 g/kg 1 week pre-operatively with the allowance for a second dose within 1 week after surgical haemostasis. The objective of the study is to demonstrate non-inferiority of eltrombopag for the primary endpoint of achieving the pre-operative platelet count threshold (50 × 109/L for minor surgery; or 100 × 109/L for major surgery) and sustaining platelet count levels above the threshold for 1 week after surgical haemostasis is achieved, without the use of rescue treatment. Secondary endpoints include thrombosis, bleeding and patient satisfaction. Conclusion The Bridging ITP Trial will evaluate the efficacy and safety of eltrombopag as an alternative to IVIG in the peri-operative setting for patients with ITP. The protocol was designed to provide a management strategy that can be applied in clinical practice. ClinicalTrials.gov Identifier NCT01621204.

BACKGROUND Thrombopoietin receptor agonists are new treatments for patients with chronic immune thrombocytopenia (ITP). How one of these agent, romiplostim, has impacted practice patterns, especially the use of intravenous immune globulin (IVIG), has not been evaluated outside of clinical trials. STUDY DESIGN AND METHODS This was a retrospective cohort study of adult ITP patients treated with romiplostim in four Canadian centers. Patients had primary or secondary ITP and were followed for 1 year before starting weekly romiplostim treatment. We compared IVIG use, clinical outcomes, and cost before and after romiplostim. RESULTS Twenty-nine patients with ITP received romiplostim. Median age was 54 years (interquartile range [IQR], 45-63 years) and patients had a median of two prior ITP treatments (IQR, 1-4) including splenectomy (n = 7). Median platelet (PLT) count was 23 × 109 before and 124 × 109 after romiplostim. Median duration of romiplostim treatment was 3.7 months. Patients used a median of two IVIG infusions per year before and 0.7 per year after starting romiplostim (p = 0.16). For patients who received weekly romiplostim for at least 1 month (n = 19), IVIG infusions were three (IQR, 1-5) per year before and 0.7 (IQR, 0.4-1.6) per year after romiplostim. Results were squewed by two high IVIG users. Nineteen (66%) patients discontinued romiplostim treatment during follow-up because of lack of response (n = 8), sustained response (n = 5), toxicities (n = 4), or response to splenectomy (n = 2). Overall health care costs were similar before and after romiplostim when concomitant treatments, nursing resources, and hospitalizations were considered. CONCLUSIONS Romiplostim was associated with improved PLT counts and fewer IVIG infusions for most ITP patients. In practice, romiplostim was generally not continued long term and was cost neutral for overall ITP management.