Characteristics of SGN-CD33A. (A) Structure of SGN-CD33A. (B) Homogeneity of drug loading on SGN-CD33A as determined by reverse-phase chromatography (PLRP). The ADC was treated with sodium cyanoborohydride for 1 hour at room temperature followed by a 15-minute incubation with 10 mM dithiothreitol. Peak areas were integrated for the unloaded (L0, H0) and drug-loaded (H1, H2) antibody chains and were used to calculate the average drug-load per antibody. H, heavy chain; L, light chain.