Effect of Ibrutinib on Hmphocytic Leukemia: a Single-Center Experience

In the era of novel agents, Bruton tyrosine kinase (BTK) inhibitors have changed the dynamics of treating chronic lymphocytic leukemia. However, small studies have shown conflicting results regarding the additive humoral dysfunction with their use.

We prospectively compared vaccine responses in patients on ibrutinib (n = 10) with matched controls (n = 16) and analyzed whether a protein-based (tetanus-diphtheria toxoid) or a carbohydrate (Pneumovax) moiety will result in an improved immunological response.

An appropriate serological response in IgG titers for diphtheria was seen in 40% of patients on ibrutinib and 31% of patients in the control group. About 30% of patients on ibrutinib and 44% of patients in the control group had an adequate response to tetanus toxoid. None of the patients on ibrutinib mounted an adequate response to Pneumovax, while 31% of patients in the control arm responded appropriately. These differences in the results were considered insignificant as all p values were greater than the cut-off of 0.05.

Our study did not show significant detrimental vaccine responses with ibrutinib and calls for larger multicenter studies to elucidate long-term effects, especially in patients with prior exposure to anti-CD20 monoclonal antibodies.