Interruption of BTK inhibitor improves response to SARS-CoV-2 booster vaccination in patients with CLL.

B-cell targeted therapies, including anti-CD20 monoclonal antibodies (mAb) and Bruton's tyrosine kinase inhibitors (BTKi), further suppress antibody (Ab) response to vaccines in patients with chronic lymphocytic leukemia (CLL). We conducted a prospective cohort study of SARS-CoV-2 vaccination in 81 CLL patients receiving BTKi ( n  = 54), venetoclax (VEN, n  = 9), or who were treatment naïve (TN, n  = 18). Anti-spike Ab were detected in 53% of patients on BTKi post-primary series and 84% post-booster, 57% of patients on VEN post-primary series and 50% post-booster, and 67% of TN patients post-primary series and 87% post-booster. T-cell response to the primary series was independent of Ab response. At the time of booster, 12 patients interrupted BTKi (median 21 d, range 8-22) and 33 continued BTKi. Among patients with detectable Ab post-booster, those who interrupted BTKi ( n  = 10) had significantly higher Ab titers (median 7149 units/mL) compared with patients who continued BTKi ( n  = 27, median 2071 units/mL, p = .04).