CRBN and breast cancer: In 2015, IMiDs as ligands of the CRBN E3 ligase have been firstly used to develop CRBN-based PROTACs for the degradation of BRD4 and FKBP12 (Winter et al., 2015), and to date CRBN-based PROTACs have been applied to more than 30 different protein targets, for the treatment of cancer and inflammation disease (Supplementary Table 1; Mullard, 2021), among which ARV-110 (Neklesa et al., 2018) (NCT03888612) and ARV471 (Flanagan et al., 2019) (NCT04072952) are in Phase I/II clinical trials for the treatment of prostate cancer (Petrylak et al., 2020) and breast cancer (BRCA), respectively.