Fsn0503h specifically induces antibody-dependent cellular cytotoxic (ADCC) killing of tumor cells through a CD16 dependent mechanism. (A, B) The dose dependent ADCC activity of Fsn0503h in (A) LoVo and (B) Aspc-1 cell lines. LoVo/Aspc-1 cells were incubated with human peripheral blood mononuclear cells (PBMCs) obtained from healthy donors which were stimulated with IL-2 (100 U/mL) at an E/T ratio of 40/1 in the presence of various concentrations of Fsn0503h. (C) ADCC activity of Fsn0503h (6670 nM) in LoVo and Aspc-1 cell line was blocked in the presence of CD16 neutralising antibody (6670 nM). The cathepsin S-negative cell line (Panc-1) was used as a negative control. *P < 0.01 (paired t-test) for Fsn0503h versus Fsn0503h+CD16 antibody.