Several additional genes, a few lawsuits and a missed IPO later, Cell Genesys Inc.'s Abgenix Inc. subsidiary appears to have caught up with GenPharm International in their race to develop a transgenic mouse that produces high affinity human antibodies to any antigen.

The picture was different in 1994, when the rivals published separate papers demonstrating that their mice produced human monoclonal antibodies to several antigens (see BioCentury, May 2, 1994). GenPharm's HuMAb-Mouse, however, also enabled class switching and somatic mutation, part of the secondary modification that produces immunoglobulin G (IgG) high-affinity antibodies. These MAbs are the ones with the greatest disease fighting potential. CEGE's mice weren't as far along, being unable to carry out the isotype switching characteristic of a mature antibody response.