mbruvica 140mg is a targeted therapy. It inhibits the function of Bruton's tyrosine kinase (BTK). BTK is a key signaling molecule of the B-cell receptor signaling complex that plays an important role in the survival of malignant B cells. It blocks signals that stimulate malignant B cells to grow and divide uncontrollably. It is not a chemotherapy drug but one of what are termed "targeted therapies."