BTK and neuroblastoma: In the current study, we observed that Bruton’s tyrosine kinase (BTK) is highly expressed in both monocytic and granulocytic MDSCs isolated from spleens of mice bearing NB tumors and administration of BTK inhibitor ibrutinib reduced MDSC-mediated immunosuppression, tumor growth, and enhanced anti-PDL1 checkpoint inhibitor therapy in mice bearing NB tumors.