British Journal of Haematology

Extreme thrombocytosis (ET, platelet count >1000 x 103/ul) is an uncommon clinical finding 1. Primary ET is associated with myeloproliferative disorders, such as essential thrombocythemia 2. Secondary ET is more common and occurs in reaction to infection, inflammation, or iron deficiency. Bleeding and thrombotic complications more frequently arise in primary ET cases 1, but have been reported with secondary ET in adults 3. Etiologies and complications associated with ET in children are less well-defined, as prior pediatric studies have been relatively small or restricted to specialized patient populations 4,5. We aimed to characterize ET in a large, single-center pediatric cohort.

BackgroundAnti-Platelet Factor 4 (PF4) IgG antibodies that activate platelets via Fc{gamma}RIIa have been shown to be an important part of the pathophysiology of vaccine-induced immune thrombocytopenia and thrombosis (VITT). There is now extensive literature on its presentation and initial management. There is no literature however on what happens to these patients following discharge. MethodsWe collected clinical data and samples from seven patients presenting with VITT and followed them up for 82-145 days. We also collected clinical samples from them at last follow-up. Testing for anti-PF4/heparin antibodies was done using an anti-PF4/heparin enzymatic immunoassay. Flow Cytometry was used to look at Fc{gamma}RIIa levels on patient platelets. Light Transmission Aggregometry with patient serum and healthy donor / patient platelets was used to analyse platelet responsiveness, in the presence and absence of PF4. FindingsAll patients were discharged on direct oral anticoagulants. Two patients remain completely symptom free, three have ongoing headaches, two have residual neurological deficits. Two patients developed mild thrombocytopenia and worsening headache (but without cerebral venous sinus thrombosis) and were retreated, one of these with rituximab. All patients, except the one treated with rituximab, had similar anti-PF4 antibody titres at 80-120 days to their levels at diagnosis. Platelets from patients at follow-up had normal levels of Fc{gamma}RIIa and had normal responses to thrombin and collagen-related-peptide. Patient serum from diagnosis strongly activated healthy donor platelets in the presence of PF4. Serum from follow-up was much weaker at stimulating platelets, even in the presence of PF4. InterpretationThis study shows that despite similar PF4 antibody titres at diagnosis and during follow-up, there are further differences in patient serum, that are not apparent from currently used testing, that result in lower levels of platelet activation during the follow-up period. Further understanding of these factors are important in order to assess duration of anticoagulation for these patients. FundingThis work was supported by an Accelerator Grant (AA/18/2/34218) from the British Heart Foundation (BHF) and by a National Institute for Health Research (NIHR) grant. Key pointsO_LIPF4 antibody titres do not reduce up to 4-months post ChAdOx1 nCoV-19 in patients with VITT C_LIO_LIDespite similar PF4 antibody titres, diagnostic serum is more potent at activating platelets in the presence of PF4 than follow-up serum. C_LI

AimsTo evaluate the association between platelet indices and platelet count severity in patients with primary immune thrombocytopenia during routine post-treatment follow-up. MethodsThis retrospective observational study included patients with primary immune thrombocytopenia followed at a single tertiary care center between 2011 and 2025. Demographic and laboratory data were obtained from medical records. Platelet count severity was categorized as less than 30 x 10^9/L, 30 to 100 x 10^9/L, and greater than 100 x 10^9/L. Platelet indices, including mean platelet volume (MPV) and platelet distribution width (PDW), were analyzed using the most recent complete blood count obtained during routine follow-up after treatment initiation. Continuous variables were summarized as median and interquartile range. Comparisons across platelet count categories were performed using the Kruskal-Wallis test with post hoc Mann-Whitney U testing. Correlation analysis and simple linear regression were also conducted. ResultsA total of 243 patients were identified, of whom 232 met the inclusion criteria. Platelet distribution width differed significantly across platelet count severity categories (Kruskal-Wallis p < 0.001) and demonstrated a strong inverse association with platelet count. Mean platelet volume also showed a statistically significant difference across platelet count groups (Kruskal-Wallis p = 0.007), although the association was weaker and less consistent compared with PDW. Regression analysis confirmed a significant association between platelet count and PDW. ConclusionPlatelet distribution width is more closely associated with platelet count severity than mean platelet volume in patients with primary immune thrombocytopenia during routine post-treatment follow-up. PDW may represent a useful adjunctive laboratory parameter when interpreted alongside platelet count in routine clinical practice.

BackgroundImmunocompromised patients, including those with haematological malignancies, are among the high-risk group to develop severe coronavirus disease 2019 (COVID-19) complications. The effectiveness of passive immunotherapy with convalescent plasma (CP) on such patients diagnosed with COVID-19 has not been reviewed. Therefore, the aim of this review was to systematically appraise the current evidence for the efficacy of this therapy in haematological malignancies patients with COVID-19 infection. MethodsA comprehensive search was conducted up-to October 2021, using four databases: PubMed, Web of Science, Science Direct, and Scopus. Two reviewers independently assessed the quality of the included studies. Data collection analysis were performed using Microsoft Excel 365 and GraphPad Prism software. Results17 studies met the inclusion criteria; these records included 258 COVID-19 patients with haematological malignancies and treated with CP therapy (CPT). The main findings from the reviewed data suggests CPT may be associated with improved clinical outcomes including (a) higher survival rate, (b) improved SARS-CoV-2 clearance and presence of detectable anti-SARS-CoV-2 antibodies post CP transfusion, (c) improved hospital discharge time, and recovery after 1 month of CP therapy. Furthermore, treatment with convalescent plasma was not associated with development of adverse events. ConclusionOwing to its safety and beneficial effects in improving clinical outcomes, CPT appears to be an effective supportive therapeutic option for haematological malignancy patients infected with COVID-19.

Infections are increasingly recognized as a common complication of chimeric antigen receptor (CAR) T-cell therapy. The incidence of clinically-defined infection after CD19.CAR T-cell therapy for relapsed/refractory lymphoma ranges from 60-90% in the first year after CAR T-cell therapy and is the most common cause for non-relapse mortality. However, infectious risk after CAR T-cell therapy targeting other malignancies is not well understood. Herein, we report for the first time, infectious complications after CD30.CAR T-cell treatment for patients with Hodgkins lymphoma and peripheral T-cell lymphoma. Since CD30 is only expressed on a subset of activated T and B-cells, we hypothesized that CD30.CAR T-cell patients would have reduced incidence and severity of infections after infusion compared to CD19.CAR T-cell patients. We retrospectively evaluated all 64 patients who received CD30.CAR T-cells at a single institution between 2016-2021, and assessed infections within one year after cell infusion, comparing these data to a contemporary cohort of 50 patients who received CD19.CAR T-cells at the same institution between 2018-2021. 23 CD30.CAR T-cell patients (36%) and 18 CD19.CAR T-cell patients (36%) developed a microbiologically confirmed infection. Infection severity and bacterial infections were higher in the CD19.CAR T-cell group compared to CD30.CAR T-cell recipients who more commonly had grade 1 respiratory viral infections. Our data reflect expected outcomes for severity and infection type in CD19.CAR T-cell patients and provide a benchmark for comparison with the novel CD30.CAR T-cell product. Although our findings require replication in a larger cohort, they have implications for antimicrobial prophylaxis guidelines after CD30.CAR T-cell therapy. KEY POINTS1) The incidence of infections within the first year after CD30.CAR T-cell therapy was equivalent to that following CD19.CAR T-cell therapy 2) Viral infections were more common after CD30.CAR T-cell therapy but bacterial infections predominated after CD19.CAR T-cell therapy.

BackgroundHaemophagocytic lymphohistiocytosis (HLH) is rare, results in high mortality and is increasingly being diagnosed. Little is known about what is driving the apparent rise in the incidence of this disease. MethodsUsing national linked electronic health data from hospital admissions and death certification cases of HLH that were diagnosed in England between 1/1/2003 and 31/12/2018 were identified using a previously validated approach. We calculated incidence rates of diagnosed HLH per million population using mid-year population estimates by calendar year, age group, sex and associated comorbidity (haematological malignancy, inflammatory rheumatological or bowel diseases (IBD)) associated with the diagnosis of HLH. We modelled trends in incidence and the interactions between calendar year, age and associated comorbidity using Poisson regression. FindingsThere were 1674 people with HLH diagnosed in England between 2003 and 2018. The incidence rate quadrupled (Incidence Rate Ratio (IRR) 2018 compared to 2003: 3.88 95% Confidence Interval (CI) 2.91 to 5.28), increasing 11% annually (adjusted IRR 1.11 95% CI 1.09 to 1.12). There was a rising trend in all age groups except those aged less than 5 years. There was a transition across the age groups with greater increases in those aged 5 to 14 years of HLH associated with rheumatological disease/IBD compared to HLH associated with haematological malignancy, with similar increases in HLH associated with both co-morbidities for those 15-54, and greater increases in associated haematological malignancies for those 55 years and older. InterpretationThe incidence of HLH in England has quadrupled between 2003 and 2018, increasing 11% annually. Substantial variation in the incidence occurred by age group and by HLH associated comorbidities with inflammatory rheumatological diseases or IBD associated HLH increasing more among the young and middle age groups, whereas in older age groups the largest increase was seen with haematological malignancy-associated HLH. Evidence before this studyThere is a paucity of population-based data on the epidemiology of HLH worldwide. The available evidence relies mostly upon a collection of cases series published in The Lancet in 2014 which described 2197 cases of HLH in adults reported in the literature to that point. Almost all of these were from tertiary referral specialist centres and/or described in small case series. The incidence of HLH has only been described in a few reports - and mainly this has focused on children with primary HLH. No previous studies have been large enough to examine trends in incidence by age, sex, underlying risk factors and calendar time. Added value of this studyThis study quantifies the incidence of diagnosed HLH for the first time in a nationwide manner for all age groups. It reports on 1674 patients with HLH from England and shows that there is substantial variation in the incidence by age group, associated disease and calendar time. The results imply reasons for the increase in HLH could be related to the increasing occurrence of haematological cancer, inflammatory rheumatological or bowel diseases and the treatments given for these conditions. This study has been carried out in partnership with the National Congenital Anomalies and Rare Diseases Registration Service and the methodology described can in future be applied to many rare diseases that as yet lack a way of quantifying crucial epidemiological metrics. Implications of all the available evidenceThe incidence of HLH is rising rapidly in people older than 5 years of age. This could be due to an increase in the biologic, immunomodulation or immunosuppressive therapy being used in people with haematological cancer and inflammatory rheumatological and bowel diseases. Further work should focus on how to minimise the risk of HLH occurring, or to improve treatment of this often fatal disease among those who need treatment for an associated comorbidity.

IntroductionMyelodysplastic syndromes (MDS) are hematologic malignancies characterized by changes in haematopoiesis and a high risk for progressing into acute myeloid leukemia (AML). In this retrospective registry based real-world study, from two Finnish hospital data lakes we characterized specialised health care treated MDS patients, their treatment landscape, outcomes, and healthcare resource utilization. MethodsThis study consisted of adult patients with MDS diagnosed in either of two hospital districts in Finland: hospital district of Southwest Finland (HDSF) and Pirkanmaa hospital district (PHD). Two different time windows were used depending on data availability: 1.1.2010-31.12.2019 (HDSF) and 1.1.2012-31.12.2019 (PHD). Electronic health record data, including demographics, diagnoses, and medications was accessed via the respective hospital data lakes and dates and causes of death data was collected from Statistics Finland. ResultsWe identified 565 adult MDS patients, of whom 424 received active life-prolonging treatment at specialized healthcare and 141 were treated with watchful observation or supportive care at primary care. 72 patients were treated with azacitidine and 26 patients received allogeneic hematologic stem cell transplant. Median overall survival for the specialty healthcare treated patients was 27,5 months (95 confidence interval [CI] 24,1-35,2) and costs per patient year were 17 563{euro}. ConclusionThis hospital data lake-based analysis identified patient groups with differing disease severity and need for treatment. High-risk, azacitidine treated patients have suboptimal outcomes and high costs, highlighting the need for new therapeutic approaches to prevent disease progression and reduce disease burden.

Thrombosis remains the leading cause of morbidity and mortality for patients (pts) with polycythemia vera (PV), yet PV clinical trials are not powered to identify interventions that improve thrombosis-free survival (TFS). Such trials are infeasible in a contemporary PV cohort, even when selecting "high-risk" pts based on Age >60 and thrombosis history, because thousands of patients would be required for a short-term study to meet TFS endpoint. To address this problem, we used artificial intelligence and machine learning (ML) to dynamically predict near-term (1-year) thrombosis risk in PV pts with high sensitivity and positive predictive value (PPV) to enhance pts selection. Our automation-driven data extraction methods yielded more than 16 million data elements across 1,448 unique variables (parameters) from 11,123 clinical visits for 470 pts. Using the AutoGluon framework, the Random Forest ML classification algorithm was selected as the top performer. The full (309-parameter) model performed very well (F1=0.91, AUC=0.84) when compared with the current ELN gold-standard for thrombosis risk stratification in PV (F1=0.1, AUC=0.39). Parameter engineering, guided by Gini feature importance identified the 21 parameters (top-21) most important for accurate prediction. The top-21 parameters included known, suspected and previously unappreciated thrombosis risk factors. To identify the minimum number of parameters required for the accurate ML prediction, we tested the performance of every possible combination of 3-9 parameters from top-21 (>1.6M combinations). High-performing models (F1> 0.8) most frequently included age (continuous), time since dx, time since thrombosis, complete blood count parameters, blood type, body mass index, and JAK2 mutant allele frequency. Having trained at tested over 1.6M practical ML models with a feasible number of parameters (3-9 parameters in top-21 most predictive), it is clear that study cohorts of patients with PV at high near-term thrombosis risk can be identified with high enough sensitivity and PPV to power a clinical trial for TFS. Further validation with external, multicenter cohorts is ongoing to establish a universal ML model for PV thrombosis that would facilitate clinical trials aimed at improving TFS.

IntroductionUterine fibroids are known to affect >80% of premenopausal American women of African descent, and sickle cell disease is known to disproportionately affect people of varying geographical ancestries, particularly those of sub-Saharan African descent. However, previous studies have suggested the two pathologies less frequently co-occur. This study aims to evaluate the prevalence of uterine fibroids in patients with sickle cell disease across a large metropolitan area in the United States. MethodsAfrican American women with sickle cell disease (including HbSS, HbSC, and sickle cell trait genotypes) underwent pelvic imaging (CT/MRI/ultrasound) between February 2011 and August 2018 at two large hospital systems within a single academic institution. Based on retrospective review, the prevalence of uterine fibroids among this cohort was analyzed and compared to published data of fibroid prevalence amongst African American patients without sickle cell disease. ResultsPrior data estimates that the prevalence of uterine fibroids in African American women is about 32 to 40% for those aged 32 to 35 years and up to >80% in premenopausal African American women overall. When compared to the expected prevalence in this cohort, with a median age of 31 years, women with HbSS or HbSC sickle cell disease had a significantly decreased prevalence of uterine fibroids (9.6 to 10.3%), while those with sickle cell trait reflected a prevalence (44.4%) like that of the general population. ConclusionThere was a significantly lower prevalence of uterine fibroids in premenopausal American women of African heritage with sickle cell disease in the study cohort when compared to premenopausal American women of African heritage in the general population. This suggests a higher threshold to ascribe dysfunctional uterine bleeding in premenopausal African-American women with sickle cell disease to uterine fibroids, and a lower threshold to pursue an alternative diagnosis.

A growing understanding of the complexities of hematopoietic malignancies necessitates the existence of clinical recommendations that are sufficiently comprehensive. Although hereditary hematopoietic malignancies (HHMs) are increasingly recognized for conferring risk of myeloid malignancy, frequently utilized clinical recommendations have never been appraised for the ability to reliably guide HHM evaluation. We assessed established society-level clinical guidelines for inclusion of critical HHM genes and graded the strength of testing recommendations. We uncovered a substantial lack of consistency of recommendations guiding HHM evaluation. Such heterogeneity in guidelines likely contributes to refusal by payers to support HHM testing, leading to underdiagnoses and lost opportunities for clinical surveillance.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines are highly effective in healthy individuals. Patients with multiple myeloma (MM) are immunocompromised due to defects in humoral and cellular immunity as well as immunosuppressive therapies. The efficacy after two doses of SARS-CoV-2 mRNA vaccination in MM patients is currently unknown. Here, we report the case of a MM patient who developed a fatal SARS-CoV-2 infection after full vaccination while in remission after B cell maturation antigen (BCMA)-targeted chimeric antigen receptor (CAR)-T treatment. We show that the patient failed to generate antibodies or SARS-CoV-2-specific B and T cell responses, highlighting the continued risk of severe coronavirus disease 2019 (COVID-19) in vaccine non-responders. In the largest cohort of vaccinated MM patients to date, we demonstrate that 15.9% lack SARS-CoV-2 spike antibody response more than 10 days after the second mRNA vaccine dose. The patients actively receiving MM treatment, especially on regimens containing anti-CD38 and anti-BCMA, have lower antibody responses compared to healthy controls. Thus, it is of critical importance to monitor this patient population for serological responses. Non-responders may benefit from ongoing public health measures and from urgent study of prophylactic treatments to prevent SARS-CoV-2 infection.

At the beginning of the SARS-CoV-2 pandemic, transfusion of COVID-19 convalescent plasma (CCP) was considered as one of the possibilities to help severe patients to overcome COVID-19 disease. The use of CCP has been controversial as its effectiveness depends on many variables from the plasma donor and the COVID-19 patient, for example, time of convalescence or symptoms onset. This was a feasibility study assessing the safety of multiple doses of CCP in mechanically ventilated intubated patients with respiratory failure due to COVID-19. Thirty (30) patients with severe respiratory failure, in ICU, with invasive mechanical ventilation received up to 5 doses of 300 to 600 ml of CP on alternate days (0,2,4,6 and 8) until extubation, futility, or death. Nineteen patients received five doses, seven received four, and four had 2 or 3 doses. On day 28 of follow-up, 57% of patients recovered and were at home and the long-term mortality observed was 27%. The ten severe adverse events reported in the study were unrelated to CCP transfusion. This study suggests that transfusion of multiple doses of convalescent plasma (CP) is safe. This strategy may represent an option to use in new studies, given the potential benefit of CCP transfusions in the early stage of infection in unvaccinated populations and in settings where monoclonal antibodies or antivirals are contraindicated or not available. Summary boxO_LITransfusion of multiple doses (up to 5 doses) of 300-600 ml of convalescent plasma from COVID-19 recovered patients is safe as it does not induce more severe effects than a single dose. C_LIO_LIIndependent of the number of transfused doses, most patients had detectable levels of total and neutralizing antibodies in plasma. C_LIO_LIFuture studies are needed to determine if multiple transfusion doses are more efficient in preventing severity than a single dose. C_LI

Patients with hematologic malignancies are a high priority for SARS-CoV-2 vaccination, yet the benefit they will derive is uncertain. We investigated the humoral response to vaccination in 53 non-Hodgkin lymphoma (NHL), Hodgkin lymphoma (HL), or CLL patients. Peripheral blood was obtained 2 weeks after first vaccination and 6 weeks after second vaccination for antibody profiling using the multiplex bead-binding assay. Serum IgG, IgA, and IgM antibody levels to the spike specific receptor binding domain (RBD) were evaluated as a measure of response. Subsequently, antibody-positive serum were assayed for neutralization capacity against authentic SARS-CoV-2. Histology was 68% lymphoma and 32% CLL; groups were: patients receiving anti-CD20-based therapy (45%), monitored with disease (28%), receiving BTK inhibitors (19%), or chemotherapy (all HL) (8%). SARS-CoV-2 specific RBD IgG antibody response was decreased across all NHL and CLL groups: 25%, 73%, and 40%, respectively. Antibody IgG titers were significantly reduced (p < 0.001) for CD20 treated and targeted therapy patients, and (p = 0.003) for monitored patients. In 94% of patients evaluated after first and second vaccination, antibody titers did not significantly boost after second vaccination. Only 13% of CD20 treated and 13% of monitored patients generated neutralizing antibodies to SARS-CoV-2 with ICD50s 135 to 1767, and 445 and > 10240. This data has profound implications given the current guidance relaxing masking restrictions and for timing of vaccinations. Unless immunity is confirmed with laboratory testing, these patients should continue to mask, socially distance, and to avoid close contact with non-vaccinated individuals. Statement of Translational RelevanceNon Hodgkin lymphoma (NHL) and Chronic Lymphocytic leukemia (CLL) patients who are treated with anti-CD20 antibody therapy, BTK inhibitor therapy, or who are monitored with active disease, have decreased antibody response to SARS-CoV-2 vaccination and decreased antibody titers compared to healthy controls. Antibody titers do not boost following second vaccination, and very few patients generate neutralizing antibodies against SARS-CoV-2. This data is of particular importance, given the recent guidance from the CDC that vaccinated patients no longer need to be masked indoors as well as outdoors. Patients with NHL or CLL who fall into these categories should not consider their immunity from vaccination to be assured. If infected with SARS-CoV-2, they should be a high priority for monoclonal antibody directed therapy. Unless immune response to vaccination is confirmed with laboratory testing, they should continue to mask, socially distance, and to avoid close contact with non-vaccinated individuals.

Patients with BRCA1/2-mutated ovarian, breast, prostate, or pancreatic tumors can be treated with poly ADP-ribose polymerase (PARP) inhibitors. PARP inhibitors, however, are known to cause therapy-related myeloid neoplasms (t-MN) in a subset of patients. Predisposing factors to t-MN development in the context of PARP inhibitor exposure are not well described. To determine the frequency of t-MN in these patients, an institutional cohort of 265 patients with exposure to PARP inhibitors was identified. A subset of these patients with PARP inhibitor-related cytopenias underwent bone marrow biopsies. Among 265 patients, 17 (6.4%) underwent a bone marrow biopsy, which yielded a therapy-related hematologic diagnosis in 47% (8/17). Breast cancer metastasis to the marrow was found in one patient, and hemophagocytic lymphohistiocytosis was found in another. We analyzed the molecular characteristics of t-MNs in 13 PARP inhibitor-exposed patients, including five additional PARP inhibitor-exposed patients diagnosed with t-MNs in community practices. Among patients with t-MNs, five had acute therapy-related myeloid leukemia (t-AML), six were diagnosed with therapy-related myelodysplastic syndrome (t-MDS), and two had therapy-related clonal cytopenias of uncertain significance (t-CCUS). Complex karyotypes were found in four of seven patients who underwent karyotyping (57%). Next-generation sequencing identified TP53 mutations in 7 of 9 patients analyzed (78%). Among patients with germline testing, four (40%) did not have a germline mutation identified, four (40%) had a BRCA1 pathogenic/likely pathogenic (P/LP) variant, and two (20%) had a BRCA2 P/LP variant. Four patients received supportive care and/or observation after blood cancer diagnosis, and six received t-MN-directed therapy. The median survival for patients who received t-MN-directed treatment was 148 days. While cytopenias, particularly anemia, are known to occur with PARP inhibitor therapy, a subset of patients develop chronic cytopenias requiring bone marrow biopsy to evaluate for t-MN. Our study informs the expected findings of such biopsies.

Fetal hemoglobin (HbF) prevents the polymerization of sickle hemoglobin (HbS). HbF, measured usually as a percent of total hemoglobin (%HbF), is inversely associated with the severity of sickle cell disease (SCD) but fails to capture the distribution of HbF concentrations within red blood cells (RBCs). The relative proportion of HbF and HbS within a RBC is reflected by the HbF:HbS ratio whereas HbF/F-cell quantifies the absolute amount of HbF/RBC. While correlated, HbF:HbS ratio and HbF/F-cell are not interchangeable. In the context of mean corpuscular hemoglobin (MCH), HbF/F-cell approximates whether sufficient HbF is present to inhibit HbS polymerization. We examined the association of mean HbF/F-cell with sub-phenotypes of sickle cell disease in three independent cohorts. Both %HbF and HbF/F-cell were significantly associated with multiple clinical and laboratory features of SCD; however, HbF/F-cell demonstrated stronger associations with clinical severity measures across cohorts. Higher HbF/F-cell was associated with fewer clinical events, reduced hemolysis, and mortality. Changes in HbF/F-cell after hydroxyurea treatment were associated with ~11-13% reduction in acute events in patients with <1 pg increase and >60% reduction with a >5 pg increase in HbF/F-cell. For each pg increase in HbF/F-cell there was ~6% reduction in the rate of acute events. As a surrogate for the distribution of HbF concentrations among F-cells, HbF/F-cell adds physiologically relevant insights that could guide prognosis and treatment

Cancer-induced bone disease is a huge burden on patient lives and costs the NHS millions of pounds every year. Breast, prostate and lung cancer can all lead to poor skeletal outcomes, but patients particularly at risk are those with a diagnosis of multiple myeloma (1). Despite response to tumour targeting treatments, patients experience debilitating bone pain and fractures, affecting quality of life (2, 3). Currently, myeloma patients who are eligible, are offered treatment with induction chemotherapy followed by autologous stem cell transplant (ASCT). Most eligible patients also receive bisphosphonates, to reduce skeletal morbidity, but this treatment is not optimal, or even conducive for bone recovery. Therefore, we wanted to assess whether current induction chemotherapy regimens have the capacity to reset the bone marrow microenvironment (BMME). This prospective observational cohort study will recruit newly diagnosed myeloma patients from Sheffield Teaching Hospitals NHS Foundation Trust. Ethical approval has been granted to undergo two recruitment periods; cohort 1 (20 participants, forming a pilot study) and cohort 2 (up to 100 participants with a streamlined follow-up design). Macro-architectural skeletal bone disease will be assessed by whole-body low-dose CT (WBLDCT) scans, in which osteolytic lesions will be monitored longitudinally. Micro-architecture will be assessed by micro-CT scanning bone marrow trephine samples, and analysing changes in trabecular bone. Bone integrity will be assessed using computational models of both whole body skeletal and micro trephine images. Fasting serum samples will be collected to assess changes in bone turnover markers. This will be supported by histomorphometry and immunohistochemistry analysis of trephine sections. All samples / imaging will be performed at baseline and follow-up. Monitoring of quality of life (validated questionnaires) and occurrence of skeletal related events (SREs) will also take place. The observational period will end one year post ASCT. Data collected from this study, will provide an invaluable opportunity to comprehensively assess myeloma-induced bone disease and broaden our understanding of the disease course. It may also prove a valuable resource to guide the design of interventional clinical studies exploring novel bone-targeted therapies, including bone anabolic therapeutics, moving forward.

BackgroundLaboratory reference intervals must reflect population diversity for accurate medical decisions. The Duffy null variant lowers absolute neutrophil counts (ANC), but existing dedicated reference intervals are based on a single African American cohort. The impact across other ethnic groups and regions remains unclear, and no white blood cell count (WBC) intervals exist for Duffy null individuals. This study aimed to establish and compare Duffy null ANC and WBC reference intervals across four continents. MethodsA cross-sectional study was conducted assessing healthy Duffy null individuals from dedicated cohorts (blood donors in Namibia and Saudi Arabia, and primary care patients in the USA) and biobanks (participants from the UK and USA). Reference intervals were determined using Clinical & Laboratory Standards Institute guidelines. ResultsAmong 7,872 participants (392 from dedicated cohorts, 7,480 from biobanks), novel ANC and WBC reference intervals were established: Namibia (820-6,370/L; 2.51-9.85x 109/L), Saudi Arabia (1,090-5,100/L; 3.71-9.95x 109/L), and the USA (1,210-5,390/L; 3.00-9.66x 109/L), with no significant differences between cohorts. Institutional reference intervals misclassified 27.9% (Namibia), 50.7% (Saudi Arabia), and 21.7% (USA) as neutropenic. Biobank analyses confirmed a significantly lower ANC in Duffy null individuals compared to Duffy non-null (p<0.0001) with no significant difference in ANC between Black and non-Black Duffy null participants. ConclusionsDuffy null individuals consistently exhibit lower ANC and WBC across ethnic groups and regions. Current reference intervals overlook this variation, risking misdiagnosis and health inequities. Implementing Duffy-specific reference intervals is essential for equitable and accurate clinical decisions worldwide. Key points- Novel ANC and WBC reference intervals for Duffy null adults were established and are consistent across four continents - Current ANC reference intervals misclassify up to half of Duffy null individuals as neutropenic, contributing to global heath inequities.

Background Monoclonal gammopathy of thrombotic significance (MGTS) is a recently described chronic prothrombotic condition characterized by monoclonal anti-PF4 antibodies that are detected above the polyclonal antibody background in patient sera (i.e. present as monoclonal gammopathy of undetermined significance, MGUS). Due to conflicting data in the published literature on antibody clonality in heparin-induced thrombocytopenia (HIT), we evaluated clonality and abundance of anti-PF4 antibodies in HIT, including investigating whether an MGUS, if present in HIT, represents the causative anti-PF4 antibody. Methods Blood samples from 15 patients with HIT were subject to Platelet Factor 4-dependent antigen-based and functional tests. The unmanipulated serum antibody repertoire and isolated anti-PF4 antibodies were subjected to mass spectrometric evaluation. Results Two of the 15 HIT patients had an IgG MGUS. Notably, anti-PF4 antibodies were not synonymous with the MGUS antibody in either of the two patients. Eight of the 15 patients demonstrated monoclonal anti-PF4 antibodies, however, none of the anti-PF4 antibodies were detectable as an MGUS upon evaluation of the entire serum antibody repertoire, reflecting their low abundance. In the seven patients with multiple anti-PF4 antibodies, non-monoclonality was confirmed by analysis of deglycosylated antibody heavy chains. Conclusions Anti-PF4 HIT antibodies are monoclonal in approximately 50% of HIT patients, however, antibody abundance is low such that they are not detectable over the polyclonal IgG background (i.e. are MGUS-negative), differentiating HIT from MGTS. This observation helps explain the transient nature of HIT relative to the persistent prothrombotic state seen in MGTS.

ImportanceIn patients with hematologic malignancies, the immunogenicity of the standard 2-dose mRNA-1273 coronavirus disease 19 (COVID-19) vaccination schedule is often insufficient due to underlying disease and current or recent therapy. ObjectiveTo determine whether a 3rd mRNA-1273 vaccination raises antibody concentrations in immunocompromised hematology patients to levels obtained in healthy individuals after the standard 2-dose mRNA-1273 vaccination schedule. DesignProspective observational cohort study. SettingFour academic hospitals in the Netherlands. Participants584 evaluable immunocompromised hematology patients, all grouped in predefined cohorts spanning the spectrum of hematologic malignancies. ExposureOne additional vaccination with mRNA-1273 5 months after completion of the standard 2-dose mRNA-1273 vaccination schedule. Main Outcomes and MeasuresSerum IgG antibodies to spike subunit 1 (S1) antigens prior to and 4 weeks after each vaccination, and pseudovirus neutralization of wildtype, delta and omicron variants in a subgroup of patients. ResultsIn immunocompromised hematology patients, a 3rd mRNA-1273 vaccination led to median S1 IgG concentrations comparable to concentrations obtained by healthy individuals after the 2-dose mRNA-1273 schedule. The rise in S1 IgG concentration after the 3rd vaccination was most pronounced in patients with a recovering immune system, but potent responses were also observed in patients with persistent immunodeficiencies. Specifically, patients with myeloid malignancies or multiple myeloma, and recipients of autologous or allogeneic hematopoietic cell transplantation (HCT) reached median S1 IgG concentrations similar to those obtained by healthy individuals after a 2-dose schedule. Patients on or shortly after rituximab therapy, CD19-directed chimeric antigen receptor T cell therapy recipients, and chronic lymphocytic leukemia patients on ibrutinib were less or unresponsive to the 3rd vaccination. In the 27 patients who received cell therapy between the 2nd and 3rd vaccination, S1 antibodies were preserved, but a 3rd mRNA-1273 vaccination did not significantly enhance S1 IgG concentrations except for multiple myeloma patients receiving autologous HCT. A 3rd vaccination significantly improved neutralization capacity per antibody. Conclusions and RelevanceThe primary schedule for immunocompromised patients with hematologic malignancies should be supplemented with a delayed 3rd vaccination. B cell lymphoma patients and allogeneic HCT recipients need to be revaccinated after treatment or transplantation. Trial RegistrationEudraCT 2021-001072-41 Key pointsO_ST_ABSQuestionC_ST_ABSCan a 3rd mRNA-1273 vaccination improve COVID-19 antibody concentrations in immunocompromised hematology patients to levels similar to healthy adults after the standard 2-dose mRNA-1273 schedule? FindingsIn this prospective observational cohort study that included 584 immunocompromised hematology patients, a 3rd mRNA-1273 vaccination significantly improved SARS-CoV-2 antibody concentrations to levels not significantly different from those obtained by healthy individuals after the standard 2-dose mRNA-1273 vaccination schedule. Pseudovirus neutralization capacity per antibody of wild type virus and variants of concern also significantly improved. MeaningThe primary COVID-19 vaccination schedule for immunocompromised patients with hematologic malignancies should be supplemented with a delayed 3rd vaccination.

PurposeHCT is vital for treating hematological malignancies, relying on HLA matching between unrelated patient-donor pairs to significantly reduce adverse outcomes. Recent studies recognize the potential impact of HLA-DPB1 mismatches on HCT outcomes. Multiple approaches focus on finding better-tolerated HLA-DPB1 mismatches. Additionally, recent studies suggest matching at noncoding HLA sequence may improve HCT outcomes. This study aims to evaluate different approaches for categorizing DPB1 mismatches in patient-donor pairs and explore the potential impact of noncoding mismatches (available in class I HLA genes) on clinical outcomes. MethodsA retrospective study of 5,106 HCT pairs using Cox proportional hazards models, weighted by a machine learning algorithm, evaluates the impact of particular combinations of HLA-DPB1 mismatches in the context of noncoding HLA class I mismatches on outcomes of HCT. HLA-DPB1 mismatch criteria included T-cell epitope permissive/non-permissive mismatches, expression markers, and evolutionary clade mismatches. ResultsTwo HLA-DPB1 mismatches, using multiple criteria, lead to significant hazards of acute graft versus host disease grades 2-4, in the T cell replete group. When HLA-DPB1 mismatches occurred across evolutionary clades (DP2 allele/low-expression patient vs DP5 allele/high-expression in the donor), the deplete group showed significant hazards for treatment-related mortality (TRM) (HR=1.94, p-value=8.9x10-7) and overall survival (OS) (HR=1.67, p-value=1.3x10-5) for additive effects of noncoding mismatches with two HLA-DPB1 mismatches. ConclusionTwo HLA-DPB1 mismatches remain to predict worse outcomes. However, noncoding mismatches in HLA class I genes confer elevated hazards of TRM and OS in conjunction with mismatches across evolutionary branches of HLA-DPB1. Therefore, noncoding mismatches may inform donor selection in the presence of HLA-DPB1 mismatches and improve HCT outcomes, emphasizing the utility of comprehensive sequencing of HLA alleles in HCT settings.