<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Lorenzo Canti</style></author><author><style face="normal" font="default" size="100%">Sophie Servais</style></author><author><style face="normal" font="default" size="100%">Grégory Ehx</style></author><author><style face="normal" font="default" size="100%">Yves Beguin</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">Stéphanie Humblet-Baron</style></author><author><style face="normal" font="default" size="100%">Julika Neumann</style></author><author><style face="normal" font="default" size="100%">Adrian Liston</style></author></secondary-authors><tertiary-authors><author><style face="normal" font="default" size="100%">I Desombere</style></author><author><style face="normal" font="default" size="100%">Pieter Pannus</style></author><author><style face="normal" font="default" size="100%">Maria Goossens</style></author></tertiary-authors><subsidiary-authors><author><style face="normal" font="default" size="100%">Heyndrickx, Leo</style></author><author><style face="normal" font="default" size="100%">Aurélie Henry</style></author><author><style face="normal" font="default" size="100%">Evelyne Willems</style></author><author><style face="normal" font="default" size="100%">Stanislas Goriely</style></author><author><style face="normal" font="default" size="100%">Laurence Seidel</style></author><author><style face="normal" font="default" size="100%">Johan Michiels</style></author><author><style face="normal" font="default" size="100%">Betty Willems</style></author><author><style face="normal" font="default" size="100%">Ariën, Kevin K</style></author><author><style face="normal" font="default" size="100%">Arnaud Marchant</style></author><author><style face="normal" font="default" size="100%">Frédéric Baron</style></author></subsidiary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Predictors of neutralizing antibody response to BNT162b2 vaccination in allogeneic hematopoietic stem cell transplant recipients.</style></title><secondary-title><style face="normal" font="default" size="100%">J Hematol Oncol</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Adult</style></keyword><keyword><style  face="normal" font="default" size="100%">Aged</style></keyword><keyword><style  face="normal" font="default" size="100%">Antibodies, Neutralizing</style></keyword><keyword><style  face="normal" font="default" size="100%">BNT162 Vaccine</style></keyword><keyword><style  face="normal" font="default" size="100%">COVID-19 Vaccines</style></keyword><keyword><style  face="normal" font="default" size="100%">Hematopoietic Stem Cell Transplantation</style></keyword><keyword><style  face="normal" font="default" size="100%">Humans</style></keyword><keyword><style  face="normal" font="default" size="100%">middle aged</style></keyword><keyword><style  face="normal" font="default" size="100%">Transplantation Conditioning</style></keyword><keyword><style  face="normal" font="default" size="100%">Transplantation Immunology</style></keyword><keyword><style  face="normal" font="default" size="100%">Transplantation, Homologous</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2021</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2021 Oct 24</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">14</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;&lt;b&gt;BACKGROUND: &lt;/b&gt;Factors affecting response to SARS-CoV-2 mRNA vaccine in allogeneic hematopoietic stem cell transplantation (allo-HCT) recipients remain to be elucidated.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;METHODS: &lt;/b&gt;Forty allo-HCT recipients were included in a study of immunization with BNT162b2 mRNA vaccine at days 0 and 21. Binding antibodies (Ab) to SARS-CoV-2 receptor binding domain (RBD) were assessed at days 0, 21, 28, and 49 while neutralizing Ab against SARS-CoV-2 wild type (NT50) were assessed at days 0 and 49. Results observed in allo-HCT patients were compared to those obtained in 40 healthy adults naive of SARS-CoV-2 infection. Flow cytometry analysis of peripheral blood cells was performed before vaccination to identify potential predictors of Ab responses.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;RESULTS: &lt;/b&gt;Three patients had detectable anti-RBD Ab before vaccination. Among the 37 SARS-CoV-2 naive patients, 20 (54%) and 32 (86%) patients had detectable anti-RBD Ab 21&amp;nbsp;days and 49&amp;nbsp;days postvaccination. Comparing anti-RBD Ab levels in allo-HCT recipients and healthy adults, we observed significantly lower anti-RBD Ab levels in allo-HCT recipients at days 21, 28 and 49. Further, 49% of allo-HCT patients versus 88% of healthy adults had detectable NT50 Ab at day 49 while allo-HCT recipients had significantly lower NT50 Ab titers than healthy adults (P = 0.0004). Ongoing moderate/severe chronic GVHD (P &amp;lt; 0.01) as well as rituximab administration in the year prior to vaccination (P &amp;lt; 0.05) correlated with low anti-RBD and NT50 Ab titers at 49&amp;nbsp;days after the first vaccination in multivariate analyses. Compared to healthy adults, allo-HCT patients without chronic GVHD or rituximab therapy had comparable anti-RBD Ab levels and NT50 Ab titers at day 49. Flow cytometry analyses before vaccination indicated that Ab responses in allo-HCT patients were strongly correlated with the number of memory B cells and of naive CD4 T cells (r &amp;gt; 0.5, P &amp;lt; 0.01) and more weakly with the number of follicular helper T cells (r = 0.4, P = 0.01).&lt;/p&gt;

&lt;p&gt;&lt;b&gt;CONCLUSIONS: &lt;/b&gt;Chronic GVHD and rituximab administration in allo-HCT recipients are associated with reduced Ab responses to BNT162b2 vaccination. Immunological markers could help identify allo-HCT patients at risk of poor Ab response to mRNA vaccination.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;TRIAL REGISTRATION: &lt;/b&gt;The study was registered at clinicaltrialsregister.eu on 11 March 2021 (EudractCT # 2021-000673-83).&lt;/p&gt;
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