Monoclonal antibodies are today an established class of drugs for the treatment of various disease indications including cancer, infection and inflammatory disorders. There are more than 20 monoclonal antibodies on the market today, and their market size in 2006 exceeded US$ 16 billion. One of the main disadvantages of some of these monoclonal antibodies, which are derived at least in part from mouse antibodies, is the generation of the so called HAMA response by the human immune system, i.e. human antibodies against the mouse part of the monoclonal antibody. This unwanted immune reaction occurs quite frequently upon repeated antibody injections and may considerably impair the effect of treatment. The solution to this is the application of fully human antibodies. However, this approach has been hampered by difficulties related to a lack of suitable methods for the isolation of high affinity antibodies, so that only two fully human antibodies have so far made it to the market place.

Cytos Biotechnology has established a novel screening method for the cloning of monoclonal antibodies from human origin based on the so called DELphi™ technology. Specific B cells (i.e. the immune cells producing a certain antigen-specific antibody) are isolated from the blood of human donors and the genetic antibody information of the B cells is used for the subsequent DELphi™ screening procedure in mammalian cells. The antigen-specific antibodies resulting from the screening are of high affinity and can be easily produced in large quantities in mammalian cells. With this method, fully human monoclonal antibodies have been isolated within very competitive timelines of about 3 months (published in PNAS, 2008, 105:14336)

Proof-of-concept in animal models has been established for this novel technology by the isolation of high affine, human monoclonal antibodies targeting a chemical entity, a self-molecule, and infectious disease targets. Human monoclonal antibodies thus complement Cytos Biotechnology's core business of therapeutic vaccines and open up an opportunity to benefit from an efficient combination of proprietary in-house technologies in an area where enormous commercial potential and a high degree of product validation exist.