SARS-CoV-2 Vaccine-Induced Seroconversion and Immune Correlates in Patients with Hematological Malignancies. A Real World Study.

Background: Patients with hemato-oncological malignancies may respond insufficiently to vaccination, especially in terms of antibody titer. The antibody response depends on the type of malignancy as well as the type and timing of treatment. We intended to evaluate this using real-world data from patients of our regional hospital. This study also considers the role of immune status, including T-cell activation markers, in predicting vaccination success.

Methods: Seventeen patients of our hospital having a hematological malignancy were included in this study, including myeloma, lymphoma, as well as acute myeloid leukemia (AML) and chronic lymphoid leukemia (CLL). All patients were vaccinated against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) using Tozinameran following current recommendations. Circulating antibodies directed against the spike protein of SARS-CoV-2 were determined by a commercial immune assay. Immune status was determined from peripheral blood by flow cytometry. Both parameters were followed in fifteen patients who provided sufficient follow-up data for up to one year. Patients were categorized as responders or non-responders, and differences in diagnosis, treatment, and immune status were analyzed.

Results: Antibody response depended on both diagnosis and treatment. Active treatment directed against B-cells, such as anti-Cluster of Differentiation 20 (CD20) therapy, was associated with weak seroconversion. For CD38-as well as proteasome-directed therapies, the data suggest that responders as well as non-responders exist. Notably, low peripheral B-cell numbers and high CD3+HLADR+cell counts correlated with weak seroconversion upon vaccination.

Conclusions: We suggest that peripheral immune status can be applied as a predictive biomarker for seroconversion upon vaccinations.