Is vaccine response to SARS-CoV-2 preserved after switching to anti-CD20 therapies in patients with multiple sclerosis or related disorders?

Background: Although vaccination against SARS-CoV-2 is recommended prior to introducing anti-CD20 therapies, limited data are available regarding the evolution of post-vaccinal immunity.
Methods: This retrospective study compared anti-Spike antibody titres at 6 and 12 months from SARS-CoV-2 vaccination between patients vaccinated before switching to anti-CD20 ('Switch') and two control groups: (1) patients vaccinated under disease-modifying therapies (DMTs) other than fingolimod and anti-CD20 ('Other DMTs'); (2) patients vaccinated on anti-CD20 ('Anti-CD20'). Anti-Spike-specific T-cell responses were compared between 'Switch' and 'Anti-CD20' groups.
Results: Fifty-three patients were included in the 'Switch' group, 54 in the 'Other DMTs' group and 141 in the 'Anti-CD20' group. At 6 months, in the subset of patients who received a booster dose, the 'Switch' group had lower anti-Spike titres compared with the 'Other DMTs' group (median 241.0 IQR (88.0; 504.0) BAU/mL vs 2034 (1155; 4634) BAU/mL, p<0.001), and less patients in the 'Switch' group reached the protective threshold of 264 BAU/mL. The 'Switch' group had higher anti-Spike titres than the 'Anti-CD20' group (7.5 (0.0; 62.1) BAU/mL, p=0.001). Anti-Spike titres were not different between the 'Switch' and 'Other DMTs' groups before booster administration. These results were similar at 12 months. Spike-specific T-cell positivity was similar between the 'Switch' and 'Anti-CD20' groups at 6 and 12 months (60.4% vs 61.0%, p=0.53, and 79.4% vs 87.5%, p=0.31, respectively).
Conclusions: Despite a primary vaccination performed before the first anti-CD20 cycle, our results suggest weaker immune responses at 6 and 12 months and decreased booster efficacy after introducing anti-CD20. Patients vaccinated prior to anti-CD20 introduction might falsely be considered as fully protected by vaccination.
Competing Interests: Competing interests: CL has received consulting or travel fees from Biogen, Novartis, Roche, Sanofi, Teva and Merck Serono, and research grant from Biogen, none related to the present work. EM has received consulting or travel fees from Alexion, Biogen, Horizon, Janssen, Merck, Novartis, Sanofi and Teva, and research grant from Biogen, none related to the present work. VP has received consulting or travel fees from Gilead, ViiV, MSD, Biogen, Novartis, Roche and Merck Serono, none related to the present work. LJ, BA, CS, DS, YB, AH, LB and A-GM have no competing interest to declare.
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