Impaired booster-induced SARS-CoV-2 antibody responses in rituximab-treated B-cell lymphoma patients despite peripheral B-Cell RecoveryJurca, Tomaž (Avtor) Boltežar, Lučka (Avtor) Oražem, Miha (Avtor) Fujs Komloš, Kristina (Avtor) Pohar, Katka (Avtor) Jevnikar, Sara (Avtor) Poljak, Mario (Avtor) Mlakar-Mastnak, Denis (Avtor) Rotovnik-Kozjek, Nada (Avtor) Vratanar, Bor (Avtor) Ocvirk, Janja (Avtor) Ihan, Alojz (Avtor) lymphomaB-cellrituximabCOVID-19 vaccinesRituximab-treated patients with B-cell lymphoma exhibit profound B-cell depletion and impaired vaccine-induced antibody responses. However, it remains uncertain whether recovery of peripheral B-cell counts after rituximab is sufficient to restore effective humoral immunity following booster vaccination. Patients and methods In this prospective, single-center observational study at the Institute of Oncology Ljubljana, adult B-cell lymphoma patients treated with or previously exposed to rituximab received the Comirnaty® mRNA COVID-19 vaccine. Antibody responses to the SARS-CoV-2 spike and nucleoprotein were measured at baseline, 14 days after the second dose, and at 3, 6, 9, and 12 months. A third dose was administered at 6 months. T-cell responses (IFN-γ release) were assessed in patients before and after the primary series and booster dose. Lymphocyte subsets were analysed pre-vaccination. Adverse events and nutritional status were monitored. Results Patients undergoing anti-CD20 therapy showed absent antibody responses. Longer intervals since rituximab correlated with peripheral B-cell repopulation. However, even after reaching normal B-cell counts, patients’ antibody responses after revaccination remained significantly lower than in controls. Conclusions Rituximab is associated with impaired vaccine-induced antibody responses. Despite recovery of peripheral B-cell counts, patients with B-cell lymphoma show reduced humoral responses compared with healthy individuals following booster COVID-19 vaccination.Association of Radiology and Oncology20262026-06-03 11:59:43Neznano29699Ljubljanaslby Authors