Effect of HER2‐targeted therapy on PDX and PDX‐derived organoids generated from HER2‐positive salivary duct carcinoma.

Background: We previously established a patient‐derived xenograft (PDX) model, patient‐derived organoids (PDOs), and PDX‐derived organoids (PDXOs) for salivary duct carcinoma (SDC). Using these models, this study examined the therapeutic effect of human epidermal growth factor receptor 2 (HER2) blockade on HER2‐positive SDC. Methods: The therapeutic effect of lapatinib was assessed in SDC PDXOs with regards to cell growth, receptor/downstream signaling molecule expression, phosphorylation levels, and apoptosis. Effect of lapatinib treatment was evaluated in vivo in SDC PDX mice. Results: The siRNA knockdown of HER2 and lapatinib suppressed cell proliferation in SDC PDXOs. Lapatinib inhibited the phosphorylation of HER2 and its downstream targets, and induced apoptosis in SDC PDXOs. Lapatinib also significantly reduced tumor volumes compared with that of the control in SDC PDX mice. Conclusion: For the first time, we demonstrated the efficacy of anti‐HER2 therapy in HER2‐positive SDC using preclinical models of SDC PDX and PDXO. [ABSTRACT FROM AUTHOR]