Recent Advances in the Biology and CD123-Directed Treatment of Blastic Plasmacytoid Dendritic Cell Neoplasm.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive myeloid malignancy of the dendritic cell lineage that affects patients of all ages, though the incidence appears to be highest in patients over the age of 60 years. Diagnosis is based on the presence of plasmacytoid dendritic cell precursors expressing CD123, the interleukin-3 (IL-3) receptor alpha, and a distinct histologic appearance. Timely diagnosis remains a challenge, due to lack of disease awareness and overlapping biologic and clinical features with other hematologic malignancies. Prognosis is poor with a median overall survival of 8 to 14 months, irrespective of disease presentation pattern. Historically, the principal treatment was remission induction therapy followed by a stem cell transplant (SCT) in eligible patients. However, bridging to SCT is often not achieved with induction chemotherapy regimens. The discovery that CD123 is universally expressed in BPDCN and is considered to have a pathogenetic role in its development paved the way for the successful introduction of tagraxofusp, a recombinant human IL-3 fused to a truncated diphtheria toxin payload, as an initial treatment for BPDCN. Tagraxofusp was approved in 2018 by the United States Food and Drug Administration for the treatment of patients aged 2 years and older with newly diagnosed and relapsed/refractory BPDCN, and by the European Medicines Agency in 2021 for first-line treatment of adults. The advent of tagraxofusp has opened a new era of precision oncology in the treatment of BPDCN. Herein, we present an overview of BPDCN biology, its diagnosis, and treatment options, illustrated by clinical cases.

Hematology in the post-COVID era: spotlight on vaccine-induced immune thrombotic thrombocytopenia and a conceptual framework (the 4P's) for anti-PF4 diseases.

INTRODUCTION: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a life-threatening prothrombotic disorder first identified following the introduction of adenoviral vector vaccines for COVID-19. The condition is characterized by anti-PF4 antibodies and clinically presents with thrombocytopenia and thrombosis often in unusual anatomical sites. AREAS COVERED: In this review, we discuss the clinical presentation, diagnostic testing, and treatment of VITT. We also review VITT-like syndromes that have been described in patients without previous vaccination. We propose a conceptual framework for the mechanism of anti-PF4 diseases that includes sufficiently high levels of PF4, the presence of a Polyanion that can form immune complexes with PF4, a Pro-inflammatory milieu, and an immunological Predisposition - the 4Ps. EXPERT OPINION: Significant progress has been made in understanding the characteristics of the VITT antibody and in testing methods that can confirm that diagnosis. Future work should be directed at understanding long-term outcomes, mechanisms of thrombosis, and individual risk factors for this rare but dangerous immune-thrombotic disease.

Impact of iron supplementation on patient outcomes for women with abnormal uterine bleeding: a protocol for a systematic review and meta-analysis.

BACKGROUND: Abnormal uterine bleeding (AUB), which includes heavy menstrual bleeding (HMB), is a common condition placing women at increased risk for developing iron deficiency and iron deficiency anemia (IDA). Depletion of iron stores has negative implications on physical, social, and emotional health, as well as quality of life. Iron supplements are safe, effective, and readily available, while red blood cell (RBC) transfusions have inherent risks including infectious and immune reactions. Despite high prevalence of IDA among women with AUB, there are limited studies on the impact of iron therapies on patient outcomes. This systematic review and meta-analysis will evaluate the impact of iron supplementation on patient outcomes for women with AUB, when compared to combination therapy, no intervention, placebo, or standard of care. METHODS: We will conduct a systematic review and meta-analysis of randomized controlled trials and observational studies evaluating the impact of iron interventions on patient outcomes for women with AUB. Systematic literature searches will be conducted in major databases including MEDLINE, EMBASE, CENTRAL, CINAHL, and Web of Science. Studies assessing the impact of iron interventions on patient outcomes in women experiencing AUB, in comparison to combination therapy, no intervention, placebo, or standard of care, will be included in the review. Independent reviewers will screen for eligibility, assess risk of bias, and abstract data. Overall certainty of evidence for each outcome will be assessed using the GRADE approach. We will meta-analyze outcomes which are sufficiently homogeneous to summarize intervention effects and narratively synthesize nonhomogeneous outcomes. The main outcomes of interest are hemoglobin levels immediately prior to surgery and post-operatively, number of RBC transfusions, and adverse effects. Secondary outcomes will include length of hospital stay, intraoperative blood loss, adverse and side effects, quality of life, and iron indices. DISCUSSION: This review will evaluate the impact of iron interventions on patient outcomes in women with IDA secondary to AUB with focus on changes in hematological and iron indices, red blood cell utilization, quality of life, cost of treatment, and adverse events. The results will inform evidence-based clinical practice for the management of iron deficiency and IDA secondary to AUB. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42019137282.

Antiviral therapy defiant mixed viral retinitis post hematopoietic allogeneic stem cell transplant.

Cytomegalovirus (CMV) retinitis is an uncommon presentation post allogeneic transplant and can be vision-threatening. Our case demonstrates the occurrence of polymerase chain reaction (PCR) proven mixed viral retinitis (cytomegalovirus and varicella zoster virus) post allogeneic stem cell transplant despite multiple prophylactic antiviral therapies, including letermovir, and in the documented absence of CMV DNAemia. A 21-year-old female with acute myeloid leukemia presented with mixed viral retinitis (cytomegalovirus and varicella zoster virus) post allogenic transplant. This presentation occurred despite ongoing standard prophylaxis for both of these viruses, as well as following two courses of treatment for CMV viremia, with a documented negative CMV PCR in the blood prior to the presentation with retinitis. The patient was treated with intravenous ganciclovir and subsequently transitioned to oral valganciclovir with durable resolution of the retinitis. We report a rare case of mixed viral retinitis occurring despite multiple antiviral prophylaxes including letermovir and with PCR-documented absence of preceding CMV viremia, in a post-allogeneic stem cell transplant patient, with PCR of the aqueous fluid demonstrating two viral populations. With very little existing literature on either mixed viral retinitis or CMV retinitis during letermovir prophylaxis, this case expands the literature on both topics. CMV retinitis is an uncommon potentially vision threatening presentation post hematopoietic stem cell transplant, and can occur due to early CMV reactivation, low CD4 count, and delayed CD4 lymphocyte recovery. Letermovir has poor CNS and retinal penetration. This case highlights the need for more research on secondary prophylaxis with letermovir.

An evaluation of the clinical impacts of 7-day platelets.

BACKGROUND: In August 2017, Canadian Blood Services extended the shelf-life of platelet concentrates from 5 to 7 days. The clinical impacts of this policy change remain unclear. STUDY DESIGN AND METHODS: We used a before-after retrospective design of platelet-transfused adult inpatients in Hamilton, ON, Canada. Data were captured for 18 months before (Period 1: February 2016-July 2017) and 18 months after (Period 2: September 2017-February 2019) 7-day platelet implementation. Primary outcome was absolute platelet count increment (ACI) in univariate and multivariate analyses adjusted for confounders. Data were obtained from our institution's transfusion database, Ontario's Transfusion Transmitted Injuries Surveillance System, and the blood supplier. RESULTS: Overall, 1360 patients with single dose platelet transfusions were included in Period 1 and 1211 patients in Period 2. Median age at admission was 66 years, and approximately 40% of patients underwent cardiac surgery. Using a non-inferiority margin of -10 × 109 /L, platelets transfused during the 7-day storage period were non-inferior to those transfused in the 5-day storage period [mean count difference - 4.63 × 109 /L (95% CI -7.40 to -1.87, p = 0.0001)]. However, platelet ACIs following transfusion consistently trended lower in the 7-day group for all patients and subgroups. No differences in secondary clinical outcomes were observed. Platelet expiry reduced from 8.1 to 6.3% (p < 0.0001). CONCLUSION: Platelet transfusions following 7-day storage policy were non-inferior to transfusions in the 5-day policy period, although reduced ACIs were observed. There were no increases in adverse clinical outcomes.

Reducing use of coagulation tests in a family medicine practice setting: An implementation study.

Introduction: Clinicians often order the international normalized ratio (INR) and activated partial thromboplastin time (APTT) to evaluate for the possibility of inherited bleeding disorders despite sensitivities and specificities of 1%-2%. The most accurate tool to evaluate for bleeding disorders is a validated bleeding assessment tool (BAT). Our aim was to reduce coagulation testing by >50% in a large family practice in Ontario, Canada. Methods: We conducted an implementation study from May 2016 to February 2020. Iterative interventions included introduction of a validated BAT into the electronic medical record (EMR); removal of the APTT as a prepopulated selection from the laboratory requisition; and education targeting family medicine teams and laboratory personnel. The primary outcome was the rate of pre- and post-APTT testing. Creatinine testing was the control. Data were analyzed via an interrupted time series analysis using Stata 13. Results: Immediately following education of the laboratory personnel on coagulation testing, the APTT rate level dropped by 1.26 tests per 100 patient visits per month (p < 0.001) and was sustained until the end of the study. Meanwhile, the PT/INR and creatinine testing rate levels did not change (rate level = -0.02 per 100 visits per month, p = 0.79 and 0.49, p = 0.22 respectively). There was good uptake of the BAT following integration and 18/88 (20%) obtained a referral to hematology after BAT completion. Conclusions: Multidisciplinary, iterative interventions reduced APTT testing and enabled the use of BATs to guide hematology referrals in a large family practice.

Coagulation test understanding and ordering by medical trainees: Novel teaching approach.

Background: Coagulation testing provides a prime opportunity to make an impact on the reduction of unnecessary laboratory test ordering, as there are clear indications for testing. Despite the prothrombin time/international normalized ratio and activated partial thromboplastin time being validated for specific clinical indications, they are frequently ordered as screening tests and often ordered together, suggesting a gap in understanding of coagulation. Methods: Based on a needs assessment, we developed an online educational module on coagulation for trainees, incorporating education on testing cost, specificity, and sensitivity. Fifty participating resident physicians and medical students completed a validated premodule quiz, postmodule quiz after completion of the module, and a latent quiz 3 to 6 months after to assess longer-term knowledge retention. Trainees provided responses regarding their subjective laboratory test-ordering practices before and after module completion. Results: The median premodule quiz score was 67% (n = 50; range, 24%-86%) with an increase of 24% to a median postmodule quiz score of 91% (n = 50; range, 64%-100%). There was evidence of sustained knowledge acquisition with a latent quiz median score of 89% (n = 40; range, 67%-100%). Trainees were more likely to consider the sensitivity, specificity, and cost of laboratory investigations before ordering them following completion of the educational module. Conclusions: Using the expertise of medical educators and incorporating trainee feedback, we employed a novel approach to the teaching of coagulation to maximize its approachability and clinical relevance. We found sustained knowledge retention regarding coagulation and appropriate coagulation test ordering, and a subjective change to trainee ordering habits following participation in our educational intervention.

Treatment of vaccine-induced immune thrombotic thrombocytopenia (VITT).

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a novel prothrombotic disorder characterized by thrombosis, thrombocytopenia, and disseminated intravascular coagulation identified in hundreds of recipients of ChAdOx1 nCoV-19 (Oxford/AstraZeneca), an adenovirus vector coronavirus disease 2019 (COVID-19) vaccine. VITT resembles heparin-induced thrombocytopenia (HIT) in that patients have platelet-activating anti-platelet factor 4 antibodies; however, whereas heparin typically enhances platelet activation by HIT antibodies, VITT antibody-induced platelet activation is often inhibited in vitro by pharmacological concentrations of heparin. Further, the thrombotic complications in VITT feature much higher frequencies of atypical thrombosis, most notably cerebral vein thrombosis and splanchnic vein thrombosis, compared with HIT. In this review, we outline the treatments that have been used to manage this novel condition since its recognition in March 2021, including anticoagulation, high-dose intravenous immune globulin, therapeutic plasma exchange, corticosteroids, rituximab, and eculizumab. We discuss the controversial issue of whether heparin, which often inhibits VITT antibody-induced platelet activation, is harmful in the treatment of VITT. We also describe a case of "long VITT," describing the treatment challenges resulting from platelet-activating anti-PF4 antibodies that persisted for more than 9 months.

Anemia-Induced Bleeding in Patients with Platelet Disorders.

Anemia is not only a consequence of bleeding, but also a modifiable risk factor for bleeding in patients with thrombocytopenia or platelet function defects. In this review we outline the mechanism of anemia-induced bleeding in patients with platelet disorders, which involves a disturbance in normal red blood cell (RBC) rheology and reduced platelet margination to the endothelial surface due to a decrease in RBC mass, leading to impaired primary hemostasis and bleeding. Biologically, anemia reduces the mass of RBCs in the central column of flowing blood through a vessel resulting in fewer platelets coming into contact with the endothelial surface at the periphery of the flowing blood column. Thus, anemia results in impaired primary hemostasis. Von Willebrand factor (vWF) is another component of primary hemostasis and vWF deficiency, especially a deficiency of the highest vWF multimers, can also manifest with bleeding when concomitant anemia occurs. Clinically, patients at greatest risk for anemia-induced bleeding include patients with hematological malignancies in whom anemia and thrombocytopenia occur as a result of the underlying disease or the myelotoxic effects of treatment; patients with renal insufficiency with uremic thrombocytopathy and hypoproliferative anemia; and patients with inherited or acquired bleeding disorders affecting primary hemostasis (eg, Bernard-Soulier syndrome, von Willebrand disease) with chronic blood loss and iron deficiency anemia. Underlying abnormalities of any components of primary hemostasis plus concomitant anemia may result in major bleeding disorders; therefore, correction of remediable abnormalities-most notably, correction of the anemia- would be expected to have important clinical benefit. In this review we discuss how the correction of the anemia may lead to improvement of bleeding outcomes in patients with a primary hemostatic defect, supported by evidence from animal models, clinical trials and clinical experience.

Risk Associated With Valvular Regurgitation During Pregnancy.

BACKGROUND: Pregnancies in women with regurgitant valve lesions are generally considered low risk, but this has not been well studied. OBJECTIVES: This study determined the frequency of adverse cardiac events (CEs) in pregnant women with moderate or severe regurgitant valve lesions. METHODS: Maternal and fetal outcomes in women with moderate or severe chronic valve regurgitation enrolled in a prospective multicenter study on pregnancy outcomes were examined. Adverse CEs included heart failure, sustained arrhythmias, cardiac arrest, or death. A multivariate logistic regression model was used to identify determinants of CEs in women at the highest risk. RESULTS: Outcomes of 430 pregnancies in women with moderate or severe regurgitant lesions were examined: 145 with mitral regurgitation (MR), 101 with pulmonary regurgitation (PR), 71 with multivalve disease, 73 with tricuspid regurgitation (TR), and 40 with aortic regurgitation (AR). Most women had associated congenital or acquired heart disease. Adverse CEs occurred in 13% of pregnancies: 27% of pregnancies with multivalve disease; 15% with MR; 15% with TR; 5% with AR; and 3% with PR. Maternal mortality was rare. In women with MR, TR, or multivalve disease (n = 289), left ventricular systolic dysfunction (p = 0.001), pulmonary hypertension (p = 0.005), and cardiac events before pregnancy (p < 0.001) were important determinants of CEs during pregnancy. CONCLUSIONS: Women with AR and PR are at low risk for cardiac complications during pregnancy. While many women with MR, TR, and multivalve regurgitation do well during pregnancy, additional clinical variables help stratify those at highest risk. This new information will enhance the quality and precision of preconception counseling and pregnancy planning.

Curricular needs for training telemedicine physicians: A scoping review.

PURPOSE: The use of telemedicine, a part of 'Virtual Care', is rapidly entering mainstream clinical practice. The ideal curriculum for educating physicians to practice in this emerging field has not been established. We examined the literature to evaluate published curricula for quality and comprehensiveness through the lens of Competency-Based Medical Education (CBME). METHODS: We performed a scoping review using CanMEDS as a framework. Peer-reviewed articles describing telemedicine training curricula were identified. Trainee population, curricular points, stage of implementation, evaluation depth, country, and citations (a marker of quality) were examined. RESULTS: Forty-three curricula from 11 countries were identified, addressing all training levels and covering multiple specialties. Instructional methods included lectures (60.5%), hands-on experiences (76%), directed reading (24%), online modules (21%), reflection (13%), simulation (34%), and group discussions (16%). Hands-on curricula covered all CanMEDS roles more often. Twenty-nine of the implemented curricula were evaluated; 83% were rated positively. CONCLUSIONS: Our scoping review helps inform more comprehensive and efficacious curricula for teaching telemedicine. We suggest centering curricula on a competency-based, outcomes-oriented framework such as CanMEDS with multiple teaching modalities complementing hands-on experiences. This will facilitate rigorous telemedicine training to deliver on the promise of high-quality patient care.

Concurrent maternal and fetal tachyarrhythmia in pregnancy.

The occurrence of a maternal and fetal tachyarrhythmia together in pregnancy is exceedingly rare. We report a case of a persistent fetal atrial ectopic tachycardia occurring in conjunction with a maternal atrial tachycardia with left ventricular systolic dysfunction. Amiodarone was effective in treating both maternal and fetal arrhythmias.

Mechanisms of neurodegeneration after severe hypoxic-ischemic injury in the neonatal rat brain.

PURPOSE: Apoptosis is implicated in mild-moderate ischemic injury. Cell death pathways in the severely ischemic brain are not characterized. We sought to determine the role of apoptosis in the severely ischemic immature brain. METHODS: Seven-day old rats were randomly assigned to mild-moderate or severe cerebral hypoxia-ischemia (HI) group. After ligating the right common carotid artery, animals were subjected to hypoxia for 90min in the mild-moderate HI or 180min in the severe HI. The core and peri-infarct area were measured in H&E stained brain sections using NIS Elements software. Brain sections were processed for caspase-3, AIF and RIP3 immuno-staining. Number of positive cells were counted and compared between the two groups. RESULTS: The core constituted a significantly higher proportion of the ischemic lesion in the severely compared to the moderately injured brain (P<0.04) up to 7 days post-injury. Apoptotic cell death was significantly higher (P<0.05) in the core than the peri-infarct of the severe HI brain. In the peri-infarct area of severe HI, AIF-induced cell death increased over time and caspase-3 and AIF equally mediated neuronal death. Necroptosis was significantly higher (P=0.02) in the peri-infarct of the severe HI lesion compared to the moderate HI lesion. In males, but not in females, apoptosis was higher in moderate compared to severe HI. CONCLUSIONS: Caspase-independent cell death plays an important role in severe ischemic injury. Injury severity, timing of intervention post-injury and sex of the animal are important determinants in designing neuroprotective intervention for the severely ischemic immature brain.

TLR-3 receptor activation protects the very immature brain from ischemic injury.

BACKGROUND: We have shown that preconditioning by lipopolysaccharide (LPS) will result in 90% reduction in ischemic brain damage in P7 rats. This robust LPS neuroprotection was not observed in P3 or P5 pups (corresponding to human premature infant). LPS is a known Toll-like receptor 4 (TLR-4) ligand. We hypothesized that TLRs other than TLR-4 may mediate preconditioning against cerebral ischemic injury in the developing brain. METHODS: TLR-2, TLR-3, TLR-4, and TLR-9 expression was detected in brain sections from P3, P5, and P7 rats by immuno-staining. In subsequent experiments, P5 rats were randomly assigned to TLR-3 specific agonist, poly I:C, or saline treated group. At 48 h after the injections, hypoxic-ischemic (HI) injury was induced by unilateral carotid artery ligation followed by hypoxia for 65 min. Brains were removed 1 week after HI injury and infarct volumes were compared in H&E stained sections between the two groups. RESULTS: TLR-2 and TLR-3 were highly expressed in brains of P3 and P5 but not in P7 rats. The number of TLR-4 positive cells was lower in P3 and P5 compared to P7 brains (P <0.05). TLR-3 was predominately expressed in P5 pups (P <0.05). There was no significant difference in TLR-9 expression in the three age groups. There was a significant reduction in infarct volume (P=0.01) in poly I:C compared to saline pre-treated P5 pups. Pre-treatment with poly I:C downregulated NF-κB and upregulated IRF3 expression in P5 rat ischemic brains. Pre-treatment with poly I:C did not offer neuroprotection in P7 rat brains. CONCLUSION: TLRs expression and function is developmentally determined. Poly I:C-induced preconditioning against ischemic injury may be mediated by modulation of TLR-3 signaling pathways. This is the first study to show that TLR-3 is expressed in the immature brain and mediates preconditioning against ischemic injury.