Efficacy of the BNT162b2 mRNA COVID-19 Vaccine in Patients with Chronic Lymphocytic Leukemia: A Serologic and Cellular Study

Abstract

Background: Antibody response following SARS-CoV-2 vaccination is somewhat defective in chronic lymphocytic leukemia (CLL). Moreover, the correlation between serologic response and status of cellular immunity has been poorly studied. Objective: This study was undertaken to assess humoral immune and cellular responses to the BNT162b2 messenger RNA (mRNA) COVID-19 vaccination in CLL. Methods: The presence of the spike antibodies was assessed at a median time of 14 days from the second vaccine dose of SARS-CoV-2 in 70 CLL patients followed up at a single institution. Results: The antibody response rate (RR) in CLL patients was 58.5%, compared to 100% of 57 healthy controls of the same sex and age (p < 0.0001). Treatment-naïve patients and those in sustained clinical remission after therapy had the highest RR (87.0% and 87.7%, respectively). In contrast, patients on therapy with a pathway inhibitor as monotherapy and those treated with an association of anti-CD20 antibody were unlikely to respond to the SARS-CoV-2 vaccine (52% and 10%, respectively). In multivariate analysis, early Rai stage (OR, 0.19 [0.05-0.79]; p = 0.02) and no previous therapy (OR, 0.06 [0.02-0.27]; p < 0.0001) were found to be independent predictors of vaccination response. An increase in absolute NK cells (i.e., CD16/CD56 positive cells) in patients with a serological response was found following the second dose of vaccine (p = 0.02). Conclusions: These results confirm that serological response to the BNT162b2 vaccine in patients with CLL is impaired. A third boosting vaccine dosage should be considered for these patients.