In this review, we will discuss the mechanisms of action and clinical utility of several classes of targeted therapy used in blood cancers, including inhibitors of different types of tyrosine kinase enzymes (BCR-ABL, FLT3 and BTK), BCL-2 inhibitors, phosphoinositide 3-kinase inhibitors, nuclear export inhibitors, immune therapies (monoclonal antibodies, radioimmunoconjugates, chimeric antigen receptor T-cells, immune checkpoint inhibitors, and bispecific antibodies), and proteasome-dependent drugs (proteasome inhibitors and proteolysis targeting chimeras). This evidence concerns the gene BTK and hematopoietic and lymphoid system neoplasm.