Abstract 3586: Immune response to COVID-19 vaccination in patients with B-cell malignancies after CD19 CART cell therapy
Authors: Iraguha Thierry , Dahiya Saurabh , Avila Stephanie , Rapoport Aaron , Luetkens Tim , Atanackovic Djordje 
Published: June 2022

Abstract
Introduction: Patients with hematologic malignancies are at an increased risk of morbid/mortality from COVID-19. Our prospective clinical study evaluated immune responses to COVID-19 mRNA vaccines in patients with B-cell lymphoma who had received CD19-directed chimeric antigen receptor (CAR) T cell therapy.
Methods: We measured SARS-CoV-2 neutralizing activity of plasma from 18 patients and 4 healthy controls (HC) and antibody titers against viral spike proteins (S1, S2, RBD) including their “delta” variants using an enzyme-linked immunoassay (ELISA). We measured B cell subpopulations in the patients’ blood using flow cytometry.
Results: We found that the peripheral blood plasma from 3/4 HCs showed substantial SARS-CoV-2 neutralizing activity already at 4 weeks after the first dose of COVID-19 mRNA vaccine while none of the CD19 CART patients evidenced any antibody-mediated neutralizing activity at the same point in time. At 4 weeks after receiving the second dose of the vaccine, all 4 HCs showed complete neutralizing activity. In marked contrast, only 1 of 14 CART patients evidenced any relevant antibody-mediated SARS-CoV-2 neutralizing activity. Assessing whether a globally insufficient antibody-mediated immunity was the underlying cause of the lack of a response to the COVID-19 vaccine in our CART patients, we found that IgG antibody levels against common microbial and viral antigens like influenza, Epstein-Barr virus (EBV), Cytomegalovirus (CMV), and tetanus toxoid, were comparable to those observed in HCs. However, while at 4 weeks post second dose of the vaccine the HCs showed high levels of vaccine-induced IgG antibody titers against all the viral spike proteins (S1, S2, RBD), including the “delta” variants of the S1 and RBD proteins, the vast majority of our CART patients did not evidence any SARS-CoV-2-specific antibodies. Importantly, a third “booster” vaccination did not lead to an improvement in the antiviral immunity in the 4 CART patients analyzed. When we assessed B cell subpopulations in the blood of patients and HCs, we found that prior treatments had completely eradicated all CD19+/CD20+ B cells in the patients while numbers of long-lived memory plasma cells were comparable to those of HCs.
Conclusions: In this study, 17 of 18 patients with lymphoma who received CD19 CART therapy had very poor immunoreactivity to 1-3 doses of mRNA-based COVID-19 vaccines. Importantly, antibody responses to common recall antigens were preserved, suggesting impaired immune response primarily against novel antigens like SARS-COV-2. This lack of immunoreactivity against novel antigens was probably based on the eradication of earlier-stage B cell subpopulations after treatment with anti-CD19 and anti-CD20 immunotherapies.
Citation Format: Thierry Iraguha, Saurabh Dahiya, Stephanie Avila, Aaron Rapoport, Tim Luetkens, Djordje Atanackovic. Immune response to COVID-19 vaccination in patients with B-cell malignancies after CD19 CART cell therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3586.