As human anti-mouse antibody (HAMA) response caused by murine antibodies in humans, the usage of this kind of antibodies has been limited. With the development of antibody engineering techniques, it became possible to decrease even further the murine part of antibodies by replacing the hypervariable loops of a fully human antibody with the hypervariable loops of the murine antibody of interest, using an approach called complementarity-determining region (CDR) grafting. These antibodies, called ‘humanized antibodies’, are 85-90% human and are even less immunogenic than chimeric antibodies.