Desmopressin in non-severe haemophilia A: Test-response and clinical outcomes in a single Canadian centre review.

INTRODUCTION: Desmopressin is an effective haemostatic agent for patients with non-severe haemophilia A; however, response may differ between patients of similar severity. Responsiveness is classified based on various cut-off values for plasma levels of FVIII post-desmopressin administration. Patients may be classified differently depending on the values chosen. AIM: To classify desmopressin response in non-severe haemophilia A patients with respect to current test-response definitions. Also, to characterize relationships between test response and clinical outcome of desmopressin use. METHODS: Current desmopressin test-response definitions were obtained from the literature. We adopted peak FVIII level (at 1 hour post-administration) ≥50 IU/dL and <20 IU/dL as complete and no response, respectively, thereby satisfying most reported definitions. Test-responses and clinical outcomes of use between 2007 and 2017 for adult mild/moderate haemophilia A patients were reviewed and correlated. RESULTS: All patients classified as complete responders (n = 31; peak FVIII ≥50 IU/dL) and the majority of partial responders (n = 11; peak FVIII ≥20 to <50 IU/dL) had good clinical outcomes after desmopressin use for a variety of bleeding episodes and procedures. Two non-responders (peak FVIII <20 IU/dL) given desmopressin for minor bleeding/procedures also had good clinical outcomes. One patient with a partial test-response (peak FVIII 23 IU/dL) required additional factor concentrate to achieve haemostasis. CONCLUSIONS: Based on our review, we suggest that the determination of desmopressin responsiveness should consider both the change in plasma FVIII levels as well as clinical outcomes associated with prior therapeutic use.

Acquired factor XIII deficiency: A review.

Acquired factor XIII (FXIII) deficiency is a rare bleeding disorder that can manifest with spontaneous or delayed life-threatening hemorrhage. Causes of acquired deficiency include immune-mediated inhibition, as well as non-immune FXIII hyperconsumption or hyposynthesis. The occurrence of acquired FXIII deficiency can be idiopathic or may be associated with comorbidities, such as malignancies or autoimmune disorders. Recognition of acquired FXIII deficiency and its underlying cause is imperative, as treatment options vary depending on the etiology. Diagnosis requires quantitative FXIII testing in addition to supplemental inhibitor studies if the clinical situation suggests an immune-mediated pathophysiology. Treatment may involve FXIII replacement, antifibrinolytic administration, and/or inhibitor eradication. However, treatment targets and thresholds are undefined in acquired FXIII deficiency. This review will focus on the clinical characteristics, diagnostic issues and therapeutic options for both immune and non-immune acquired FXIII deficiency. Cases are described to illustrate the clinical features of acquired FXIII deficiency.

PT-VWD posing diagnostic and therapeutic challenges - small case series.

Despite the increased worldwide awareness, over the last decade, of the platelet-type von Willebrand Disease (PT-VWD), many uncertainties remain around this rare platelet bleeding disorder. This report aims to correctly identify and study the phenotype of new patients and highlights the diagnostic and therapeutic challenges this disease remains to pose. We describe four PT-VWD cases confirmed by genetic analysis in which either the diagnosis and/or the treatment posed challenge. We provide the details of the clinical presentation, laboratory analysis, and the treatment and the responses in each case. We show that in addition to type 2B VWD, PT-VWD can be misdiagnosed as idiopathic thrombocytopenic purpura, neonatal alloimmune thrombocytopenia, and unexplained gestational thrombocytopenia. The disease can be diagnosed as early as 1 year of age and with phenotypically normal parents. Bleeding in some patients can be managed successfully using Humate P and DDAVP combined with tranexamic acid with no significant thrombocytopenia. We provide for the first time an evidence of an efficient response to rFVIIa in PT-VWD. Anaphylactic reaction to VWF preparations may be related to PT-VWD and the development of HLA antibodies is not uncommon. Progressive thrombocytopenia with normal VWF levels can be seen with PT-VWD and the platelet count was normalized at 2.5 weeks postpartum in one case. We conclude that these studies represent a record of clinical observations/interventions that help improve diagnoses/management of PT-VWD, highlight the variations in age and clinical presentations, laboratory diagnostic approaches, the importance of genetic testing for accurate diagnosis and consideration of therapeutic alternatives.

Analysis of the role of von Willebrand factor, platelet glycoprotein VI-, and α2ß1-mediated collagen binding in thrombus formation.

Rare missense mutations in the von Willebrand factor (VWF) A3 domain that disrupt collagen binding have been found in patients with a mild bleeding phenotype. However, the analysis of these aberrant VWF-collagen interactions has been limited. Here, we have developed mouse models of collagen-binding mutants and analyzed the function of the A3 domain using comprehensive in vitro and in vivo approaches. Five loss-of-function (p.S1731T, p.W1745C, p.S1783A, p.H1786D, A3 deletion) and 1 gain-of-function (p.L1757A) variants were generated in the mouse VWF complementary DNA. The results of these various assays were consistent, although the magnitude of the effects were different: the gain-of-function (p.L1757A) variant showed consistent enhanced collagen binding whereas the loss-of-function mutants showed variable degrees of functional deficit. We further analyzed the impact of direct platelet-collagen binding by blocking glycoprotein VI (GPVI) and integrin α2ß1 in our ferric chloride murine thrombosis model. The inhibition of GPVI demonstrated a comparable functional defect in thrombosis formation to the VWF(-/-) mice whereas α2ß1 inhibition demonstrated a milder bleeding phenotype. Furthermore, a delayed and markedly reduced thrombogenic response was still evident in VWF(-/-), GPVI, and α2ß1 blocked animals, suggesting that alternative primary hemostatic mechanisms can partially rescue the bleeding phenotype associated with these defects.

The C-type lectin receptor CLEC4M binds, internalizes, and clears von Willebrand factor and contributes to the variation in plasma von Willebrand factor levels.

Genetic variation in or near the C-type lectin domain family 4 member M (CLEC4M) has been associated with plasma levels of von Willebrand factor (VWF) in healthy individuals. CLEC4M is a lectin receptor with a polymorphic extracellular neck region possessing a variable number of tandem repeats (VNTR). A total of 491 participants (318 patients with type 1 von Willebrand disease [VWD] and 173 unaffected family members) were genotyped for the CLEC4M VNTR polymorphism. Family-based association analysis on kindreds with type 1 VWD demonstrated an excess transmission of VNTR 6 to unaffected individuals (P = .0096) and an association of this allele with increased VWF:RCo (P = .029). CLEC4M-Fc bound to VWF. Immunofluorescence and enzyme-linked immunosorbent assay demonstrated that HEK 293 cells transfected with CLEC4M bound and internalized VWF. Cells expressing 4 or 9 copies of the CLEC4M neck region VNTR showed reduced interaction with VWF relative to CLEC4M with 7 VNTR (CLEC4M 4%-60% reduction, P < .001; CLEC4M 9%-45% reduction, P = .006). Mice expressing CLEC4M after hydrodynamic liver transfer have a 46% decrease in plasma levels of VWF (P = .0094). CLEC4M binds to and internalizes VWF, and polymorphisms in the CLEC4M gene contribute to variable plasma levels of VWF.

A Pharmacist-Managed Hydroxyurea Prescribing Protocol Improves Uptake and Optimization among Patients with Sickle Cell Disease.

Sickle cell disease (SCD) is a common genetic disorder with potentially serious sequelae that can be effectively treated with hydroxyurea. Despite its favorable benefit-risk profile, hydroxyurea uptake in patients with SCD is low. A pilot study was conducted at the Southern Alberta Rare Blood and Bleeding Disorders (SARBBDs) Comprehensive Care Program between January 2020 and September 2023 to assess the implementation of a pharmacist-led protocol for supporting the uptake of hydroxyurea among eligible patients with SCD and optimizing its dosing. The protocol standardized the prescription, monitoring, dose titration, and patient counselling by a clinic pharmacist. The number of patients enrolled in the SARBBDs program increased from 98 in January 2020 to 168 in 2023. During this period, the proportion of patients on hydroxyurea increased from 37.8% to 62.5%, the proportion of patients on hydroxyurea who were at a maximum tolerated dose (MTD) increased from 35.1% to 63.8%, and the average hemoglobin F level increased from 13.9% to 19.7%. The mean time to reach MTD was 10 months and required eight pharmacist interventions, six laboratory assessments, and three dose increases. Hydroxyurea continuation rates were high, with most discontinuations resulting from loss to follow-up or transition to a transfusion management strategy. This real-world pilot study demonstrated that implementation of a pharmacist-led prescribing and monitoring protocol nearly doubled hydroxyurea uptake and achievement of MTD in patients with SCD managed in a rare blood disorders clinic.

The Canadian "National Program for hemophilia mutation testing" database: a ten-year review.

A reference genotyping laboratory was established in 2000 at Queen's University, Kingston, to provide genetic testing for Hemophilia A (HA) and B (HB) and create a Canadian mutation database. Canadian hemophilia treatment centers and genetics clinics provided DNA and clinical information from November 2000 to March 2011. The factor VIII (F8) gene was analyzed in 1,177 patients (47% of HA population) and 787 female family members and the factor IX (F9) gene in 267 patients (47% of HB population) and 123 female family members, using Southern Blot, PCR, conformation sensitive gel electrophoresis, and/or direct sequencing. The mutation detection rates for HA and HB were 91% and 94%, respectively. 380 different F8 mutations were identified: inversions of intron 22 and intron 1, 229 missense, 45 nonsense, eight deletions, 70 frameshifts, 25 splice site, and one compound mutation with a splice site and intron 1 inversion. Of these mutations, 228 were novel to the Hemophilia A Database (HADB, http://hadb.org.uk/). A total 125 different F9 mutations were identified: 80 missense, 12 frameshift, 12 splice site, nine nonsense and seven promoter mutations, three large deletions, and two compound mutations with both missense and nonsense changes. Of these mutations, 36 were novel to the International Haemophilia B Mutation database (http://www.kcl.ac.uk/ip/petergreen/haemBdatabase.html). The Canadian F8 and F9 mutation database reflects the allelic heterogeneity of HA and HB, and is similar to previously described populations. This report represents the largest and longest duration experience of a national hemophilia genotyping program documented, to date.

Geographic disparities in the care and outcomes in adult chronic immune thrombocytopenia.

INTRODUCTION: Despite expert-based recommendations, real-world adherence to immune thrombocytopenia (ITP) guidelines is unclear. The impact of geographic and socioeconomic disparities on the quality of care and outcomes is unknown. We sought to determine the association between geographic remoteness and material deprivation on ITP care and outcomes. METHODS: We conducted a multi-centre retrospective cohort study of adults with chronic ITP requiring a second-line therapy between 2012 and 2019 in the province of Alberta, Canada. Socioeconomic status was measured using the Pampalon material deprivation index quintiles. Geographic disparities were assessed by the driving distance to a major centre, with geographic remoteness defined as >200 km from major centre. We examined the impact of geographic and material deprivation on quality of care, resource utilization (hospitalizations, transfusions), and outcomes (major bleeding, all-cause mortality and ITP-related mortality). Cox proportional hazards models were used to examine the impact of geographic remoteness, rural residence and material deprivation on overall survival and ITP-related survival. RESULTS: We included 326 ITP patients, median age of ITP diagnosis was 57 years, 182 (56 %) were female. Most patients (58 %) lived within 20 km of a major centre, whereas 49 (15 %) lived in a geographically remote area (>200 km). Geographic remoteness was significantly associated with material deprivation and lower likelihood of management by hematologists (84 % vs 99 %, P = 0.0001). It was also associated with lower rates of hepatitis C (71 % vs 89 %, P = 0.005) and hepatitis B testing (69 % vs 86 %, P = 0.03), and a non-significant trend towards lower rates of HIV testing (73 % vs 83 %, P = 0.051) compared with those <20 km from a major centre. Incomplete hyposplenic vaccinations among splenectomized patients (52 %), early splenectomy within 12 months of ITP diagnosis (35 %), inappropriate platelet transfusions (41 %), and inappropriate hospitalizations for asymptomatic thrombocytopenia (16 %) were common regardless of geographic distribution. There were 28 (9 %) ITP-related deaths (major bleeding or infections), most occurred within the first year of ITP diagnosis. Material deprivation, but not geographic remoteness, was an independent predictor of all-cause mortality (aHR 1.9, 95 % CI 1.1-3.3 in the most deprived quintile vs least deprived quintile). Rural residence trended towards increased hazard of ITP-related deaths (aHR 1.7, 95 % CI 0.9-3.2). CONCLUSION: We demonstrated substantial deviations of ITP care from consensus guidelines, and geographic disparities in access to care and diagnostic workup. Future quality improvement initiatives are critical to improve the quality of care and reduce inequities.

A Scan of Pleiotropic Immune Mediated Disease Genes Identifies Novel Determinants of Baseline FVIII Inhibitor Status in Hemophilia-A.

Hemophilia-A (HA) is caused by heterogeneous loss-of-function factor (F)VIII gene (F8)-mutations and deficiencies in plasma-FVIII-activity that impair intrinsic-pathway-mediated coagulation-amplification. The standard-of-care for severe-HA-patients is regular infusions of therapeutic-FVIII-proteins (tFVIIIs) but ~30% develop neutralizing-tFVIII-antibodies called "FVIII-inhibitors (FEIs)" and become refractory. We used the PATH study and ImmunoChip to scan immune-mediated-disease (IMD)-genes for novel and/or replicated genomic-sequence-variations associated with baseline-FEI-status while accounting for non-independence of data due to genetic-relatedness and F8-mutational-heterogeneity. The baseline-FEI-status of 450 North American PATH subjects-206 with black-African-ancestry and 244 with white-European-ancestry-was the dependent variable. The F8-mutation-data and a genetic-relatedness matrix were incorporated into a binary linear-mixed model of genetic association with baseline-FEI-status. We adopted a gene-centric-association-strategy to scan, as candidates, pleiotropic-IMD-genes implicated in the development of either ³2 autoimmune-/autoinflammatory-disorders (AADs) or ³1 AAD and FEIs. Baseline-FEI-status was significantly associated with SNPs assigned to NOS2A (rs117382854; p=3.2E-6) and B3GNT2 (rs10176009; p=5.1E-6), which have functions in anti-microbial-/-tumoral-immunity. Among IMD-genes implicated in FEI-risk previously, we identified strong associations with CTLA4 assigned SNPs (p=2.2E-5). The F8-mutation-effect underlies ~15% of the total heritability for baseline-FEI-status. Additive genetic heritability and SNPs in IMD-genes account for >50% of the patient-specific variability in baseline-FEI-status. Race is a significant determinant independent of F8-mutation-effects and non-F8-genetics.

Approach to the diagnosis and management of common bleeding disorders.

Mild mucocutaneous bleeding symptoms are common in the general population. Differentiating normal from pathological bleeding complaints begins with a detailed bleeding history that assesses: the pattern (primary versus secondary hemostasis), the severity, and the onset (congenital versus acquired) of bleeding. Bleeding assessment tools have been developed to aid in determining whether bleeding symptoms are outside of the normal range. Although the clinical pattern of bleeding and family history directs laboratory investigations, von Willebrand disease, the most common and best characterized of the primary hemostatic disorders, is often the first diagnosis to be considered. Clinical management focuses on the particular symptoms experienced by the patient. Medical interventions include replacement of the factor that is deficient or defective, or indirect treatments, such as antifibrinolytics (tranexamic acid), desmopression, and hormone-based therapy (e.g., oral contraceptive pill for menorrhagia).

Treatment patterns and outcomes of second-line rituximab and thrombopoietin receptor agonists in adult immune thrombocytopenia: A Canadian retrospective cohort study.

BACKGROUND: The optimal choice of second-line treatment for immune thrombocytopenia (ITP) is unclear. Guidelines recommend either rituximab, splenectomy, or thrombopoietin receptor agonists (TPO-RA). There is, however, scarce data comparing treatment patterns, outcomes and resource utilization across second-line treatments. Despite Canada's universal healthcare system, publicly funded access to second-line ITP therapies is highly variable across provinces/territories. OBJECTIVES: To describe treatment patterns and compare health service utilization and outcomes among recipients of second-line rituximab and TPO-RA for ITP. METHODS: In this multicentre retrospective cohort study, we included adults who received second-line ITP therapies rituximab, eltrombopag and romiplostim (2012-2020) in Alberta, Canada. Patients were identified through a provincially-funded special drug access (STEDT) program. We examined treatment patterns, predictors of second-line treatment, hospitalizations, blood product utilization, and outcomes. Kaplan-Meier survival curves were used to estimate the cumulative incidence of ITP-related hospitalizations (bleeding or infections), overall survival (OS) and relapse-free survival (RFS). Cox proportional hazards regression was used to examine the impact of second-line therapy on OS. RESULTS: 223 patients received rituximab (67 %), eltrombopag (29 %), and romiplostim (4 %). TPO-RA recipients experienced significantly longer time from ITP diagnosis to second-line therapy compared with rituximab recipients (15.9 vs 6.7 months, P < 0.0001), accompanied by significantly higher platelet and IVIG utilization prior to second-line therapy. Age (adjusted odds ratio [aOR] 1.04, 95 % CI 1.02-1.07, P < 0.0001) and prior intracranial hemorrhage (aOR 12.7, 95 % CI 1.6-272.8, P = 0.03) were significant predictors of second-line TPO-RA. TPO-RA is associated with a trend towards longer median RFS (6.3 vs 3.8 years, P = 0.06) compared with rituximab, and similar rates of ITP-related hospitalizations, major bleeding, and thromboembolism. Age, time period, and Charlson comorbidity index, but not second-line ITP therapy, were significant predictors of OS. CONCLUSIONS: Our study identified older age and intracranial hemorrhage as predictors of second-line TPO-RA prescription in a real-world practice. There were no significant differences in hospitalizations and outcomes between second-line rituximab and TPO-RA, although delayed initiation of TPO-RA was associated with higher blood product utilization.

Paraneoplastic acquired haemophilia A in extensive-stage small cell lung cancer (ES-SCLC) in the era of immunotherapy.

Small cell lung cancer (SCLC) is a deadly and rapidly progressive disease that can present with various paraneoplastic syndromes on initial workup. Acquired factor VIII (FVIII) deficiency, also known as acquired haemophilia A (AHA), has been identified as a rare paraneoplastic syndrome in SCLC. Here, we present a 61-year-old woman with a massive gastrointestinal bleed and prolonged activated partial thromboplastin time (PTT) in the emergency department. She was diagnosed with rare paraneoplastic AHA secondary to extensive-stage SCLC (ES-SCLC). She was treated with high-dose steroids and factor bypassing agents, which led to the resolution of bleeding and undetectable FVIII inhibitor levels. She was subsequently treated for ES-SCLC with carboplatin, etoposide and atezolizumab. This case report highlights a rare clinical presentation of paraneoplastic AHA that necessitates prompt recognition in patients with SCLC with ongoing bleeding and elevated PTT.

A case that illustrates the challenges of managing pregnant patients with antithrombin deficiency: More questions than answers.

Using an illustrative case of a patient with antithrombin (AT) deficiency who developed a recurrent venous thromboembolism (VTE) in pregnancy despite therapeutic low-molecular-weight heparin (LMWH), we highlight what is known in the literature and address areas of controversy through a series of questions around the case. The questions we address include the role of anti-Xa monitoring for patients with past VTE on antepartum LMWH, what treatment regimen is recommended for pregnant patients who develop a recurrent VTE while on therapeutic anticoagulation, the role of antepartum AT concentrate prophylaxis, and the management of labor/delivery, epidural anesthesia and postpartum anticoagulation. We also describe practical considerations for use of AT concentrate, including teaching our patient to self-infuse AT concentrate at home with support of a hemophilia treatment center (HTC), and the direct and indirect costs of AT concentrate for secondary prophylaxis.

Pregnancy loss in women with von Willebrand disease: a single-center pilot study.

: The risk of pregnancy loss in von Willebrand disease (VWD) has been inconsistently reported. Von Willebrand factor (VWF) is a known regulator of angiogenesis, so has the potential to affect placental function. We sought to determine the risk of pregnancy loss and placenta-mediated pregnancy complications in women with VWD, compared with women without VWD. Women with VWD followed in the Southern Alberta Rare Blood and Bleeding Disorders Clinic were invited to participate in a questionnaire (February-June 2014). The same questionnaire was sent to women without VWD identified in a low-risk obstetrical clinic in Calgary, Alberta, Canada. The primary outcome was the proportion of pregnancies that ended in pregnancy loss. Secondary outcomes were preeclampsia, fetal growth restriction, placental abruption, and preterm labor less than 37 weeks gestation. Of the 30 (31.6%) VWD participants that responded, 26 (86.7%) were diagnosed with Type 1 VWD, of which 11 (42.3%) had VWF antigen or activity levels less than 30%. In women with VWD, there were 20 pregnancy losses out of 80 pregnancies [25.0%, 95% confidence interval (CI), 16.81-35.48], compared with eight losses out of 50 pregnancies in the control group (16.0%, 95% CI, 8.34-28.51; P = 0.28). There was no difference in the risk of preeclampsia (1.7 versus 0%, P = 1.00) or preterm labor (16.7 versus 7.1%, P = 0.23) among VWD and control groups. There were no other placenta-mediated pregnancy complications reported. There is no significant difference in pregnancy loss between women with and without VWD; however, a large multicenter study is needed to clarify the risk of pregnancy loss in women with VWD.

Endogenous factor VIII synthesis from the intron 22-inverted F8 locus may modulate the immunogenicity of replacement therapy for hemophilia A.

Neutralizing antibodies (inhibitors) to replacement factor VIII (FVIII, either plasma derived or recombinant) impair the effective management of hemophilia A. Individuals with hemophilia A due to major deletions of the FVIII gene (F8) lack antigenically cross-reactive material in their plasma ("CRM-negative"), and the prevalence of inhibitors in these individuals may be as high as 90%. Conversely, individuals with hemophilia A caused by F8 missense mutations are CRM-positive, and their overall prevalence of inhibitors is <10% (ref. 2). Individuals with the F8 intron 22 inversion (found in ∼50% of individuals with severe hemophilia A) have been grouped with the former on the basis of their genetic defect and CRM-negative status. However, only ∼20% of these individuals develop inhibitors. Here we demonstrate that the levels of F8 mRNA and intracellular FVIII protein in B lymphoblastoid cells and liver biopsies from individuals with the intron 22 inversion are comparable to those in healthy controls. These results support the hypothesis that most individuals with the intron 22 inversion are tolerized to FVIII and thus do not develop inhibitors. Furthermore, we developed a new pharmacogenetic algorithm that permits the stratification of inhibitor risk for individuals and subpopulations by predicting the immunogenicity of replacement FVIII using, as input, the number of putative T cell epitopes in the infused protein and the competence of major histocompatibility complex class II molecules to present such epitopes. This algorithm showed statistically significant accuracy in predicting the presence of inhibitors in 25 unrelated individuals with the intron 22 inversion.

The evolution and value of bleeding assessment tools.

A personal history of excessive mucocutaneous bleeding is a key component in the diagnosis of a number of mild bleeding disorders, including von Willebrand disease (VWD), platelet function disorders (PFD), and coagulation factor deficiencies. However, the evaluation of hemorrhagic symptoms is a well-recognized challenge for both patients and physicians, because the reporting and interpretation of bleeding symptoms is subjective. As a result, bleeding assessment tools (BATs) have been developed and studied in a variety of clinical settings. This work has been pioneered by a group of Italian researchers, and the resultant 'Vicenza Bleeding Questionnaire' stands as the original BAT. In this review, we will discuss the modifications of the Vicenza Bleeding Questionnaire that have taken place over the years, as well as the validation studies that have been published. Other BATs that have been developed and published will be reviewed, as will the special situations of assessing pediatric bleeding as well as menorrhagia. Lastly, the clinical utility of BATs will be discussed including remaining challenges and future directions for the field.

Why is my patient bleeding or bruising?

The evaluation of a patient presenting with bleeding symptoms is challenging. Bleeding symptoms are frequently reported by a normal population, and overlap significantly with bleeding disorders, such as type 1 Von Willebrand disease. The history is subjective; bleeding assessment tools significantly facilitate an accurate quantification of bleeding severity. The differential diagnosis is broad, ranging from defects in primary hemostasis, coagulation deficiencies, to connective tissue disorders. Finally, despite significant clinical evidence of abnormal bleeding, many patients will have not an identifiable disorder. Clinical management of bleeding disorders is highly individualized and focuses on the particular symptoms experienced by the patient.