The present disclosure relates to compounds according to Formula I (I) or a pharmaceutically acceptable salt and/or solvate thereof, as well as compositions including such compounds and uses thereof, where R1 is an unsubstituted C1-C12 alkyl; and R2, R3, and R4 are each independently H or —C(O)—(unsubstituted C1-C12 alkyl). Among other things, the present disclosure evidences that the significant upregulation of CD20 by the inhibition of a-mannosidase enzymes by compounds of the present technology potentiates the activity of anti-CD20 mAbs and importantly sensitize cell lines that are resistant to the action of these antibodies.