Particularly, HVH-2930 exhibits potent efficacy against trastuzumab-resistant HER2+ breast cancer and reasonable pharmacokinetic and toxicity profiles, which would promote the clinical application of HSP90 CTIs.454,455 Among peptide-based CTIs, penisuloxazin A binds to oxidize cysteine residues (Cys572, Cys597 and Cys598) at a site of HSP90 CTD, distinct from ATP binding pocket. This evidence concerns the gene HSP90AB1 and breast cancer.