Formats for Antibody Therapeutics

The earliest reformatting of antibodies involved limited proteolysis of MAb to yield either monovalent Fab fragments or bivalent F(ab )2 fragments depending upon the protease used and the isotype of the MAb (97). Currently, Fab and F(ab )2 fragments are more conveniently derived by recombinant expression in E. coli (98). 

Marcel Dekker, Inc. 270 Madison Avenue, New York, New York 10016 

One marketed antibody therapeutic, ReoPro, is in Fab rather than IgG format (Table 1). In addition, one F(ab )2 fragment derived by limited proteolysis of murine MAb is currently in phase III therapy trials (Table 2) (1,3). Thus far, recombinant scFv (113) and F(ab )2 (114) fragments have been tested in the clinic and more recently PEGylated versions of Fab and F(ab )2 fragments (see below). 

---