Cellular and humoral Immune response to mRNA COVID-19 vaccination in subjects with chronic lymphocytic leukemia

Chronic Lymphocytic Leukemia (CLL) is predominantly a B-lymphocyte leukemia associated with immune defects that are often exacerbated by CLL directed therapies. SARS-CoV-2 infection poses a significant risk of illness or mortality to CLL patients, and while SARS-CoV-2 vaccines are highly effective in immunocompetent individuals, efficacy varies substantially in immunocompromised patients, including those with CLL. To date, studies of COVID-19 vaccine immune responses in immunocompromised hosts have largely relied on semi-quantitative antibody titers that only partially characterize vaccine-elicited immune responses and do not measure B or T-cell specific responses that may also play a protective role in vaccinees. Here, we report RBD-specific antibody as well as B-cell and T-cell responses in an observational cohort of sixteen CLL subjects who received mRNA vaccination against SARS-CoV-2, finding a strong association between CLL treatment and vaccine immunogenicity, with important implications for vaccination timing in the context of CLL treatment or recovery from prior treatment.