HSPB1 and breast cancer: In conclusion, circVDAC3 mediates trastuzumab deruxtecan (T-DXd) resistance in breast cancer by competitively binding to HSPB1 in competition with ubiquitinating enzymes, which prevents the ubiquitination-mediated degradation of HSPB1, upregulates the expression of HSPB1 protein, and consequently inhibits ferroptosis (72).