Ibrutinib combined with low‐dose histone deacetylases inhibitor chidamide synergistically enhances the anti‐tumor effect in B‐cell lymphoma

Aberrant activity of histone deacetylases (HDACs) is frequently detected in B‐cell lymphomas, which indicated the therapeutic implications of HDAC inhibitors for B‐cell malignancies. We have discovered that lymphoma cells treated with HDAC inhibitor presented with activation of Bruton tyrosine kinase (BTK) which played an important role in the development of B‐cell malignancies. Therefore, our study intended to explore whether the addition of ibrutinib (BTK inhibitor) to chidamide (HDAC inhibitor) could generate combined anti‐tumor effects in B‐cell lymphomas. Using cell viability assay, cell cycle and apoptosis kit, we demonstrated an evident synergistic action of ibrutinib and chidamide in inhibiting tumor cell proliferation and motility. Consistent with in vitro data, the synergistic anti‐tumor effects were also observed in multiple tumor‐bearing mice models. By performing RNA‐seq and flow cytometry of tumor tissue, the enhancement of anti‐tumor immunity was observed with the co‐treatment of chidamide and ibrutinib. Together, these mechanistic insights indicated that simultaneously targeting BTK and HDAC could be a promising clinical therapy for B‐cell lymphomas.