Impaired mRNA Based COVID-19 Vaccine Response in Patients with B-Cell Malignancies after CD19 Directed CAR-T Cell Therapy

Introduction: Patients with hematologic malignancies are at an increased risk of morbidity and mortality from COVID-19 disease (Vijenthira, Blood 2020). This is likely a result of combination of immunodeficiency conferred by the disease and the therapeutics. The immunogenicity of the COVID-19 vaccines in patients with exposure to CD19 directed Chimeric Antigen Receptor (CAR)-T cell therapy is not established. CD19 CAR-T cell therapies cause B-cell aplasia, which in turn can affect humoral immune response against novel antigens. Herein, we present results from our prospectively conducted clinical study to evaluate immune responses against mRNA based COVID-19 vaccines in patients with lymphoma who have received CD19 directed CAR-T cell therapy. Methods: All patients and healthy controls were enrolled in a prospective clinical study evaluating immune responses against commercial COVID-19 RNA vaccines in patients with hematologic malignancies. Plasma samples were generated from heparinized peripheral blood of 4 heathy controls (HCs) receiving the same vaccines and 19 B cell lymphoma patients treated with CD19 CAR- T cells. Samples from ~4 weeks post second dose of the vaccine (d56) were available for 14 CAR-T patients, for 5 CAR-T patients samples were available from ~4 weeks after the first dose (d28). Plasma samples were analyzed in an enzyme-linked immunosorbent assay (ELISA) using different full-length recombinant SARS-CoV-2 proteins and control proteins. Neutralizing activity was measured using the cPass Neutralization Antibody Detection Kit (GenScript Biotech). Results: Results from 4 healthy controls and 19 patients (12 males and 7 females) with lymphoma are reported. Median age for the lymphoma patients is 65 years. Eleven patients had large B cell lymphoma, 5 had follicular lymphoma and 3 had mantle cell lymphoma as primary diagnoses. Seventeen patients had advance stage disease (III/IV stage) and had received a median of 3 prior lines of therapy. All patients received CD19 directed CAR-T cell therapy. Ten patients received Moderna vaccine and 9 received Pfizer vaccine. Median time between CAR-T infusion and first COVID-19 vaccine was 258 days. While the peripheral blood plasma from 3/4 HCs already showed substantial SARS-CoV-2 neutralizing activity at ~4 weeks after the first dose of COVID-19 mRNA vaccine, none of the 5 CD19 CAR-T patients analyzed evidenced any antibody-mediated neutralizing activity in their blood at the same point in time (Figure 1A). Around 4 weeks after receiving the second dose of the vaccine, all 4 HCs tested evidenced complete or almost complete neutralizing activity (Figure 1B). In marked contrast, only 1 out of 14 CAR-T patients analyzed evidenced any relevant antibody-mediated SARS-CoV-2 neutralizing activity in their blood (Figure 1B). Interestingly, when we asked whether a globally insufficient antibody-mediated immunity was the underlying cause of the lack of a response to the COVID-19 vaccine in our CAR-T patients, we found that that was clearly not the case since anti-Flu, -TT, and -EBV responses were equivalent to the ones observed in HCs (Figure 2A). However, while at ~4 weeks post second dose of the vaccine the HCs showed marked antibody titers against all the viral spike proteins including their "delta" variants (Figure 2B), that was not the case for our CAR-T patients. The vast majority of our CAR-T patients did not evidence IgG antibody responses against any of the SARS-CoV-2 proteins analyzed such as S1, S1 delta, RBD, RBD delta, or S2 (Figure 2B). Conclusion: In this prospectively conducted clinical study, 18 of 19 patients with lymphoma who have received CD19 CAR-T therapy had poor immunogenicity against mRNA based COVID-19 vaccines as measured by neutralization assays and antibody titers. The antibody titers against B.1.617.2 (delta variant, S1 and RBD protein) were also demonstrably poor. The antibody response to common pathogens (flu, EBV, TT) were preserved, suggesting impaired immune response against novel antigens. Long-term follow-up of this study is ongoing. APR and DJ contributed equally Figure 1 Figure 1. Disclosures Dahiya: Kite, a Gilead Company: Consultancy; Atara Biotherapeutics: Consultancy; BMS: Consultancy; Jazz Pharmaceuticals: Research Funding; Miltenyi Biotech: Research Funding. Hardy: American Gene Technologies, International: Membership on an entity's Board of Directors or advisory committees; InCyte: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Membership on an entity's Board of Directors or advisory committees.