CDK7 and breast carcinoma: CDK7 inhibition (THZ1) impacts both wild-type and LBD-mutant ER, decreasing CDK7-mediated phosphorylation and expression of ER-dependent genes, thereby reducing cell proliferation in vitro and in vivo.352–354 Importantly, CDK7 inhibitors seem effective not only as monotherapy but also in combination with endocrine therapy (e.g. fulvestrant, tamoxifen) in vitro and in human breast cancer xenograft models.343,354,355