Inhibitory effect of disitamab vedotin on breast cancer cells with different HER-2 expression levels in tumor organoid culture system
JIANG Lu
LYU Weipeng
CHEN Sijing
FANG Yanhua
LIANG Shanshan
Abstract：Objective The present study was designed to explore the inhibitory effects of the ADC drug Disitamab Vedotin(RC-48)on breast cancer cells with different HER-2 expression levels by utilizing a tumor organoid culture system.Methods Within the framework of the tumor organoid culture system,the breast cancer cell lines MCF-7(characterized by low HER-2 expression,Luminal A subtype)and BT-474(exhibiting high HER-2 expression,HER-2 positive subtype)were cultured independently and in various mixed ratios.The histological characteristics,as well as the expression levels and distribution of HER-2 in MCF-7 and BT-474 organoids,were analyzed via immunohistochemistry and immunofluorescence techniques.MCF-7 and BT-474 organoids were separately treated with Vedotin(RC-48),Disitamab,and Monomethyl auristatin E(MMAE).Additionally,a drug sensitivity test of Disitamab Vedotin(RC-48)was carried out on mixed MCF-7 and BT-474 cell ratios and on patient-derived breast cancer organoids,with the assessment conducted using the 3D-Glo method.Results In the tumor organoid culture system,immunohistochemistry and immunofluorescence analyses demonstrated that HER-2 was predominantly localized in the cell membrane.Specifically,BT-474 organoids exhibited robust HER-2 expression,while MCF-7 organoids displayed relatively low expression levels.When compared with MCF-7 organoids,RC48-ADC exerted a more pronounced inhibitory effect on BT-474 organoids,with IC50 values of 109.7 µg/mL and 2.792 µg/mL,respectively.The co-culture model further confirmed the bystander effect of RC-48,revealing that the ratio of HER-2-positive to HER-2-negative cells significantly influenced drug efficacy.Additionally,treatment with RC-48 led to a reduction in HER-2 expression in breast cancer organoids with diverse HER-2 expression levels.Conclusions The tumor organoid model can accurately mirror drug sensitivity and bystander effects.Within this model,RC-48 effectively inhibited HER-2 highly-expressing breast cancer cells,augmented the killing effect through the bystander mechanism,and downregulated HER-2 expression,thereby suggesting its potential for targeting HER2-associated breast cancer.
Keywords：tumor organoidsbreast cancerHER-2ADCbystander effectinhibition
Publication Date：2025-06-25
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：8( 1808-1815 )