Figure 1.

Acid-switching results in increased accumulation of ADCs in HER2-expressing tumor cells. Cells were incubated with 10 nM Alexa 488-labeled MMAE-conjugated antibody (WT, SG, YS or control hen egg lysozyme-specific antibody, C) for the indicated times at 37 °C, washed, incubated with 5 μg/ml Alexa 488-specific antibody and analyzed by flow cytometry. Mean fluorescence intensities (mean values of independent triplicate cell samples) for Alexa 488 fluorescence are shown. Error bars indicate SD. Statistically significant differences are indicated by * (unpaired two-tailed t-test). Two independent experiments were carried out with similar results.