A cereblon modulator with an IC50 value of 60 nM in a competitive TR-FRET assay; has a higher affinity for cereblon than the related modulators lenalidomide (IC50 = 1,500 nM) and pomalidomide (IC50 = 1,200 nM) in the same assay; has a greater potency for degradation of the CRL4 complex substrates Ikaros and Aiolos (EC50s = 1 and 0.5 nM) as well; does not degrade GSPT1 or CK1α ,