Provided are 4′-arylmethoxy isoindoline compounds, e.g., 3-(1-oxo-4-((4-((3-oxomorpholino)methyl)benzyl)oxy)isoindolin-2-yl)piperidine-2,6-dione, or an isotopologue thereof, or an enantiomer or a mixture of enantiomers thereof. Pharmaceutical compositions comprising and methods for using the compounds are also disclosed.