Fig. 2.
Impact of CD38 expression levels on CDC induction by HexaBody-CD38. (a) CD38 molecule expression (ABS) on the cell surface of 27 human tumour cell lines. Cell lines were grouped per indication and the white bars represent cell lines that did not show a concentration-response by HexaBody-CD38 in CDC assays (see Fig. 1). (b) Correlation plots of EC50-value (left panel) or maximum lysis (right panel) and CD38 density are shown. The position of the dots represents the average CDC value of a compound (HexaBody-CD38 or daratumumab) and CD38 expression levels observed for each cell line. Data points completely overlapping for HexaBody-CD38 and daratumumab are shown in red with green border. Curves represent the fitted linear relationships. For maximum lysis, the data were first linearized by logit transformation (ln [Emax/(100—Emax]), and then back transformed. (c) Antibody-induced CDC of SU-DHL-4 and JVM-13 cells was determined by flow cytometry in the presence of a CD59 blocking antibody. Representative examples out of two experiments are shown.