Provided herein are methods of treating, preventing and/or managing lymphomas and leukemias by administering to a patient Compound A (3-(5-amino-2-methyl-4-oxo-4H-quinazolin-3-yl)-piperidine-2,6-dione), or a pharmaceutically acceptable salt, solvate, or stereoisomer thereof, in combination with an anti-CD20 antibody or ibrutinib, or a pharmaceutically acceptable salt or solvate thereof