Vaccine booster improves immune response in patients treated with rituximab

Patients treated with rituximab have shown a reduced immune response after COVID-19 infections in previous studies. Therefore, the efficacy of a booster vaccine was assessed in a clinical study. Either a cellular or humoral immune response was achieved in 94% of patients, independent of the type of vaccine.

“B-cell depletion is an important treatment strategy in rheumatology,” said Prof. Michael Bonelli (Medical University of Vienna, Austria) [1]. Yet, it puts patients at risk for severe COVID-19. Previous data has shown higher rates and longer duration of hospitalisation due to COVID-19 infections in these patients [2]. In addition, higher rates of severe COVID-19 infections were associated with therapy with rituximab compared with patients treated with TNF inhibitors [3]. Moreover, a 4 times higher mortality risk has been reported in patients treated with rituximab [4]. “One of the questions we raise is whether this was due to an insufficient vaccination response in patients treated with rituximab,” Prof. Bonelli said. Previous studies have shown a reduced humoral immune response after vaccination in patients treated with rituximab compared with healthy controls. Roughly 30% of patients treated with rituximab develop neither humoral nor cellular immune response [5]. An important factor is the time between the last rituximab treatment and the vaccination, as a longer time span was associated with a higher level of antibodies. “If patients are clinically stable, we should consider postponing rituximab treatment to achieve a higher vaccination response,” Prof. Bonelli suggested.

Prof. Bonelli and his team performed a randomised blinded study to compare the efficacy and safety of an additional booster vaccination with a vector versus mRNA vaccine in 60 patients treated with rituximab who did not seroconvert after a primary mRNA vaccination [1]. At baseline, participants were vaccinated with a third dose of either an mRNA vaccine or a vector vaccine. At week 4, seroconversion rates were comparable between vector (6 of 27 patients, 22%) and mRNA (9 of 28 patients, 32%) vaccines (P=0.6). Overall, 27% of patients seroconverted. Specific T-cell responses were achieved by all participants receiving a vector booster and by 81% in mRNA-vaccinated patients. Regarding the at-risk cohort, namely patients who neither developed a humoral nor a cellular immune response after standard vaccination, booster vaccination reduced this number from 31% to 6%. “Overall, in our case, 94% of patients on rituximab developed either a cellular or humoral immune response,” Prof. Bonelli said. Vaccines were well tolerated with no severe adverse events.

According to these study results, Prof. Bonelli suggested that all older immunosuppressed patients should get an additional booster vaccination.

1. Bonelli M. Additional heterologous versus homologous booster vaccination in immunosuppressed patients without SARS-CoV-2 antibody seroconversion after primary mRNA vaccination: a randomized controlled trial. Abstract L17, ACR Convergence 2021, 03–10 November.


2. Felten R, et al. Ann Rheum Dis 2021 Sep 23;annrheumdis-2021-220549.


3. Spark JA, et al. Ann Rheum Dis 2021;80:1137-46.


4. Strangfeld A, et al. Ann Rheum Dis 2021;80:930-42.


5. Mrak D, et al. Ann Rheum Dis 2021 Oct;80(10):1345-1350.

 

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Posted on 14 January, 2022