Ibrutinib treatment improves T cell number and function in CLL patients

Area of Science:

• Immunology
• Oncology
• Pharmacology

Background:

• Ibrutinib, a Bruton's tyrosine kinase (BTK) and IL-2-inducible T cell kinase (ITK) inhibitor, exhibits immunomodulatory effects.
• The distinct roles of BTK and ITK inhibition in immune responses remain unclear, impacting the development of immune-based therapies.

Purpose of the Study:

• To investigate the differential effects of ibrutinib and acalabrutinib on T cell populations and function in chronic lymphocytic leukemia (CLL).
• To elucidate the mechanisms underlying ibrutinib's immunomodulatory actions in CLL patients.

Main Methods:

• Peripheral blood mononuclear cells from CLL patients treated with ibrutinib or acalabrutinib were analyzed serially.
• T cell phenotype, immune function, and CLL cell immunosuppressive capacity were assessed using various assays.

Main Results:

• Ibrutinib significantly increased CD4+ and CD8+ T cell numbers, particularly effector/effector memory subsets, an effect not seen with acalabrutinib.
• Ibrutinib reduced the regulatory T cell (Treg)/CD4+ T cell ratio and diminished CLL cell immunosuppressive molecules (CD200, BTLA) and IL-10 production.
• Both ibrutinib and acalabrutinib reduced PD-1 and CTLA-4 expression on T cells.

Conclusions:

• Ibrutinib enhances in vivo T cell persistence and reduces immune suppression in CLL via BTK-dependent and -independent pathways.
• The findings support the use of ibrutinib in combination immunotherapy strategies for CLL and other malignancies.