Introduction: Chimeric antigen receptor T (CAR-T) cell immunotherapy has revolutionized the prognosis of refractory or relapsed B-cell malignancies. CAR-T cell recipients have immunosuppression generated by B-cell aplasia, leading to a higher susceptibility to respiratory virus infections and poor response to vaccination.
Areas covered: This review focuses on the challenge posed by B-cell targeted immunotherapies: managing long-lasting B-cell impairment during the successive surges of a deadly viral pandemic. We restricted this report to data regarding vaccine efficacy in CAR-T cell recipients, outcomes after developing COVID-19 and specificities of treatment management. We searched in MEDLINE database to identify relevant studies until 31 March 2022.
Expert opinion: Among available observational studies, the pooled mortality rate reached 40% in CAR-T cell recipients infected by SARS-CoV-2. Additionally, vaccine responses seem to be widely impaired in recipients (seroconversion 20%, T-cell response 50%). In this setting of B-cell depletion, passive immunotherapy is the backbone of treatment. Convalescent plasma therapy has proven to be a highly effective curative treatment with rare adverse events. Neutralizing monoclonal antibodies could be used as pre-exposure prophylaxis or early treatment but their neutralizing activity is constantly challenged by new variants. In order to reduce viral replication, direct-acting antiviral drugs should be considered.
Keywords: B-cell aplasia; CAR-T cell therapy; Covid-19; SARS-CoV-2; antiviral treatment; convalescent plasma; outcomes; vaccine.