LAUSR

Patients with chronic lymphocytic leukemia (CLL) have a suboptimal humoral response to vaccination. Recently, a BNT162b2 mRNA COVID-19 vaccine was introduced with a high efficacy of 95% in immunocompetent individuals. We investigated the safety and efficacy of BNT162b2 mRNA Covid-19 vaccine in patients with CLL from nine medical centers in Israel, In total 400 patients were included, of which 373 were found to be eligible for the analysis of antibody response. The vaccine appeared to be safe and only grade 1-2 adverse events were seen in 50% of the patients. Following the second dose, antibody response was detected in 43% of the cohort. In treatment- naïve patients 61% responded to the vaccine, while only 18%, 37% and 5% of patients with CLL ongoing, previously treated with BTKi, or recent anti CD20 antibody developed responses respectively. 62% and 14% of patients treated with BCL2 monotherapy or combined with anti CD20 developed immune response respectively. Neutralizing antibodies demonstrated high concordance with positive serologic response to spike (S) protein. Based on our results a simple scoring model including recent treatment with anti-CD20, age younger than 70 years, treatment naïve status, and normal IGG, IGA, IGM and hemoglobin levels. The sum of all the above parameters can serve as a possible estimate to predict whether a given CLL patient will develop sufficient antibodies. In conclusion, the vaccine was found to be safe in patients with CLL, but its efficacy is limited particularly in treated patients.