Research Article

A Humanized Anti-CD22-Onconase Antibody-Drug Conjugate Mediates Highly Potent Destruction of Targeted Tumor Cells

Figure 2

In vitro characterization of SMCC-based immuno-RNase ADCs. (a) In situ RNase activity of the immuno-RNase ADC (1.2 μg) and ONC alone (2.0 μg) was analyzed by zymogram gel electrophoresis on 12% SDS polyacrylamide gels containing poly-rU (0.3 mg/mL) as RNase substrate. Migration distances of molecular weight markers are indicated (kDa). (b) Binding activity of huRFB4 IgG (5 nM) and the immuno-RNase ADC (5 nM) to CD22-positive Daudi cells and CD22-negative Jurkat cells is shown as median fluorescence intensity (MFI). (c) Cytotoxicity of the immuno-RNase ADC and ONC alone towards CD22-positive Daudi cells in vitro was determined by cell viability assay. Results are expressed relative to buffer-treated control cells. Data depict the mean value ± SE from one representative experiment performed in triplicate.