Apalutamide

Persistent androgen receptor (AR) signaling is a common feature of castration-resistant prostate cancer (CRPC), attributed to AR gene amplification, AR gene mutation, increased AR expression, or increased androgen biosynthesis in prostate tumors. Apalutamide is an antagonist of AR that binds directly to the ligand-binding domain of the AR with the IC50 of 16 nM. Upon binding, apalutamide disrupts AR signalling, inhibits DNA binding, and impedes AR-mediated gene transcription. Apalutamide impairs the translocation of AR from the cytoplasm to the nucleus thus reducing the concentrations of AR available to interact with the androgen response elements (AREs). Upon treatment with apalutamide, AR was not recruited to the DNA promoter regions.

Its main metabolite, N-desmethyl apalutamide, is a less potent inhibitor of AR, and exhibited one-third of the activity of apalutamide in an in vitro transcriptional reporter assay.