Disclosed is the use of (R)-1-(3-(4-amino-3-(4-phenoxyphenyl)-1H-pyrazolo[3,4-d]pyrimidin-1-yl)piperidin-1-yl)prop-2-en-1-one (ibrutinib / PCI-32765) in the manufacture of a medicament for treating diffuse large B-cell lymphoma (DLBCL) in an individual in need thereof, wherein the medicament is formulated for administration of the compound once per day in an amount of about 560 mg, in a solid oral dosage form.