No degradation products could be detected and target affinity of the glyco-engineered antibody as well as assembling of heavy and light chains was not affected by GnTIII expression. In vitro experiments showed an up to 25 fold increased ADCC lysis activity of the glyco-engineered antibody IGN312 in comparison to the wild type expression product using six Lewis Y positive target cancer cell lines (SKBR5, SKBR3, LoVo, MCF7, OVCAR3 and Kato III). However, CDC activity measured on SKBR5 target cell line was 40% reduced. The reduction of CDC activity could be prevented by using a slightly different molecular-biological approach for increased levels of complex N-linked oligosaccharides of bisected, non-fucosylated type. With this approach, it could be shown to increase ADCC activity without reducing CDC activity. In fact, in this particular case the CDC activity was even 2- fold enhanced. Binding activity for this second-generation glyco-engineered antibody measured by specific sandwich ELISA was not affected.