Figure 3. Single-agent HER2-targeted treatment effects on 2 HER2⁺ PIK3CA^mut PDXs.

(A) Schematic of experimental design. (B) Treatment response for PDX1 and PDX2. Waterfall plots show percentage change in diameter for each tumor; n = 10 tumors and 5 animals per treatment group. (C) Tumor weight at the experimental endpoint. P values in B and C indicate statistical significance based on unpaired 2-tailed Student’s t tests. (D) Representative images of the histology (hematoxylin and eosin staining; upper panels) and immunofluorescence staining for apoptosis marker (cleaved caspase-3), cell proliferation marker (phospho-histone H3), and treatment targets (HER2 and phospho-EGFR proteins). Scale bars: 100 μm. Staining was repeated twice with similar results.