want to get a vaccine response measure your antibody levels,


We have made the suggestion that vaccine response relates to the B cell numbers but this is related to the presence of depleting antibody so you could measure that instead, This is a study with ocrelizumab but this conclusion has been seen before with rituximab

Toorop AA, Hogenboom L, Bloem K, Kocyigit M, Commandeur NWM, Wijnants A, Lissenberg-Witte BI, Strijbis EMM, Uitdehaag BMJ, Rispens T, Killestein J, van Kempen ZLE. Ocrelizumab concentration and antidrug antibodies are associated with B-cell count in multiple sclerosis. J Neurol Neurosurg Psychiatry. 2023 Jan 24:jnnp-2022-330793

Background: The majority of patients with multiple sclerosis on ocrelizumab have B-cell depletion after standard interval dosing of 26 weeks. With B-cell-guided dosing patients receive their next dose when B-cell repopulation occurs. Prediction of B-cell repopulation using ocrelizumab concentrations could aid in personalising treatment regimes. The objectives of this study were to evaluate the association between ocrelizumab drug concentration, antidrug antibodies (ADAs) and CD19 B-cell count, and to define a cut-off ocrelizumab concentration for start of B-cell repopulation (defined by ≥10 CD19+ B cells/µL).

Results: A total of 452 blood samples from 72 patients were analysed. Ocrelizumab concentrations were detectable up until 53.3 weeks after last infusion and ranged between <0.0025 and 204 µg/mL after 1-67 weeks. Ocrelizumab concentration was negatively associated with B-cell count, with body mass index identified as effect modifier. We found a cut-off value of 0.06 µg/mL for start of B-cell repopulation of ≥10 cells/µL. Ocrelizumab ADAs were detectable in four patients (5.7%) with corresponding low ocrelizumab concentrations and start of B-cell repopulation.

Conclusions: Serum ocrelizumab concentration was strongly associated with B-cell count. Measurement of ocrelizumab drug concentrations and ADAs could play an important role to further personalise treatment and predict the start of B-cell repopulation.

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