Pathologic Antibodies to Platelet Factor 4 after ChAdOx1 nCoV-19 Vaccination.

BACKGROUND The mainstay of control of the coronavirus disease 2019 (Covid-19) pandemic is vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Within a year, several vaccines have been developed and millions of doses delivered. Reporting of adverse events is a critical postmarketing activity. METHODS We report findings in 23 patients who presented with thrombosis and thrombocytopenia 6 to 24 days after receiving the first dose of the ChAdOx1 nCoV-19 vaccine (AstraZeneca). On the basis of their clinical and laboratory features, we identify a novel underlying mechanism and address the therapeutic implications. RESULTS In the absence of previous prothrombotic medical conditions, 22 patients presented with acute thrombocytopenia and thrombosis, primarily cerebral venous thrombosis, and 1 patient presented with isolated thrombocytopenia and a hemorrhagic phenotype. All the patients had low or normal fibrinogen levels and elevated d-dimer levels at presentation. No evidence of thrombophilia or causative precipitants was identified. Testing for antibodies to platelet factor 4 (PF4) was positive in 21 patients, negative in 1 patient, and equivocal in 1 patient. On the basis of the pathophysiological features observed in these patients, we recommend that treatment with platelet transfusions be avoided because of the risk of progression in thrombotic symptoms and that the administration of a nonheparin anticoagulant agent and intravenous immune globulin be considered for the first occurrence of these symptoms. CONCLUSIONS Vaccination against SARS-CoV-2 remains critical for control of the Covid-19 pandemic. A pathogenic PF4-dependent syndrome, unrelated to the use of heparin therapy, can occur after the administration of the ChAdOx1 nCoV-19 vaccine. Rapid identification of this rare syndrome is important because of the therapeutic implications

Proinflammatory Effect of Carbon-Based Nanomaterials: In Vitro Study on Stimulation of Inflammasome NLRP3 via Destabilisation of Lysosomes

Carbon-based nanomaterials (C-BNM) have recently attracted an increased attention as the materials with potential applications in industry and medicine. Bioresistance and proinflammatory potential of C-BNM is the main obstacle for their medicinal application which was documented in vivo and in vitro. However, there are still limited data especially on graphene derivatives such as graphene platelets (GP). In this work, we compared multi-walled carbon nanotubes (MWCNT) and two different types of pristine GP in their potential to activate inflammasome NLRP3 (The nod-like receptor family pyrin domain containing 3) in vitro. Our study is focused on exposure of THP-1/THP1-null cells and peripheral blood monocytes to C-BNM as representative models of canonical and alternative pathways, respectively. Although all nanomaterials were extensively accumulated in the cytoplasm, increasing doses of all C-BNM did not lead to cell death. We observed direct activation of NLRP3 via destabilization of lysosomes and release of cathepsin B into cytoplasm only in the case of MWCNTs. Direct activation of NLRP3 by both GP was statistically insignificant but could be induced by synergic action with muramyl dipeptide (MDP), as a representative molecule of the family of pathogen-associated molecular patterns (PAMPs). This study demonstrates a possible proinflammatory potential of GP and MWCNT acting through NLRP3 activation

Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN):Multi-Center Collaboration and Global Registry Program

Background BPDCN is a rare, aggressive hematologic malignancy derived from the precursors of plasmacytoid dendritic cells (pDC), typically presenting with primary cutaneous dissemination and involvement of bone marrow (BM) as well as extramedullary sites including central nervous system (CNS). In 2008, it was recognized by WHO as a distinct entity and is now recognized under Myeloid/Histiocytic/Dendritic neoplasms in the 2022 5th edition update of WHO Classification. Since the recognition of this unique entity, recent efforts have been put forward for greater understanding and international collaboration, however usually focused on North America and Europe(Pemmaraju at al and Pagano et al), with this current effort representing the largest known international efforts including more parts of the world, including Asia, Middle East and Africa. Objective Due to its historical rarity and heterogeneous presentation of disease, as well as differences in availability of therapies across geo-locations, at present there is no worldwide consensus on the management of BPDCN. The outcomes remain poor, and the optimal therapy of disease remains to be determined. Launched on July 1st, 2022, the aim of our global registry is through a multi-center international collaboration to build a large database of patients with BPDCN in order to generate data-driven diagnostic and treatment recommendations. Materials and Methods The registry collects retrospective and prospective data on clinical presentation, diagnostics, treatment regimens and outcomes of patients diagnosed with BPDCN after January 1st, 2010. The data is collected globally through eCRF and Excel form. The Registry is included in ClinicalTrials.gov database (NCT05430971). Results Through July 15 th, 2023, 15 centers from 11 countries (Armenia, Canada, Cyprus, Egypt, Georgia, India, Italy, Taiwan, Turkey, UK and USA) have joined the registry and another 13 centers from USA, UK, Egypt, Iraq, Canada, Netherlands, Tajikistan, Czech Republic, Guatemala, Brazil, Serbia, Germany are onboarding. 27 retrospective and 2 prospective pts are currently included in the registry. 76 % of pts are male, in keeping with historical expectation BPDCN. Median age at diagnosis was 62 years (4-97). In 90 % of patients the tumor cells were triple positive with CD4+, CD56+, CD123+ immunophenotype. 53.6% of patients presented with cutaneous manifestation. 21% of pts received the initial treatment with AML-based regimens, 66% with ALL-based and 7% with lymphoma-based regimens. 21% of pts underwent alloSCT. 35% of pts were diagnosed after 2018, only 1 patient has received tagraxofusp, a CD123-directed therapy that received FDA approval for previously untreated or relapsed/refractory BPDCN in 2018(Pemmaraju N et al NEJM 2019). 69 % of patients achieved complete response (CR), from which 90 % were treated with ALL-based regimens. 52% of patients experienced relapse. Conclusion Current analysis of a 29-patient worldwide cohort of BPDCN demonstrates a high degree of heterogeneity in treatment regimens based on a multitude of considerations including geographic, socio-economic, drug availability, and varied clinical preferences. The outcome of ALL-based treatment was superior as compared to AML-based, but relapse rate remained high. Further global collaboration is needed to collect additional data and to identify the best diagnostic and therapeutic approaches for this challenging disease