Chronic Lymphocytic Leukemia in the SARS-CoV-2 Pandemic

Purpose of Review Chronic lymphocytic leukemia (CLL) is the most frequent lymphoproliferative disease in the elderly of the western world. Immune defective responses and treatment can worsen the immune system's competence of CLL patients. Consequently, they may present a higher incidence of recurrent severe infections, second malignancies, and reduced efficacy of vaccines. The outbreak of COVID-19 is an ongoing pandemic, and patients with comorbidities experience more severe forms of the disease. Hematological malignancies are associated with higher case fatality rates (CFRs) than other cancers. Knowledge about COVID-19 incidence, clinical course, and immune response to the infection and vaccination in CLL may contribute to design strategies that improve the outcomes of patients in the future. Recent Findings The prevalence of SARS-CoV-2 positivity in CLL is not significantly higher than seen in the general population. CFRs for CLL patients are 16.5-fold more elevated than the median reported worldwide and even higher in older patients, those who require hospitalization have significant comorbidities or need oxygen therapy. CLL status decreases the anti-SARS-CoV-2 positivity after infection or vaccination by around 40%, and the spike-specific antibody titers are 74-fold lower than healthy age-matched controls. The response rate to COVID-19 vaccines is even worse in patients with active CLL-directed therapies like BTKi, BCL-2 antagonists, or anti-CD20 monoclonal antibodies. Summary CLL patients are at a greater risk of death from COVID-19. Inherent immunosuppression of CLL and immune deficiencies caused by treatment significantly decrease the ability to produce natural or vaccine-induced anti-SARS-CoV-2 immune responses.