Over the years, the technological focus of antibody engineering has shifted as new and better strategies were adopted throughout
the antibody R&D community. Originally, mAbs were murine, constructed through a slow, laborious process of immunizing mice
and fusing lymphocytes with myeloma cell lines. Thousands of such events were screened by hand, and the best representatives
were cloned and recloned in order to develop the most specific antibodies. These antibodies were chimerized or humanized in
order to build pharmacologically effective products. But today, newer approaches, such as phage display libraries and transgenic
mice, have proven much more successful in generating fully human antibodies, and there is every indication that continuing
advances in these protocols will make the process even more user-friendly (5).
Screening of large numbers of potential antibody producing clones is now performed with robotics technology. Antibody Solutions
and Guava Technologies (acquired by Millipore) are among numerous companies that have developed automated work stations to
identify unique antibody-producing clones. Using flow cytometry and the Guava EasyCyte cell analysis platform, the system
can screen 10–20 96-well plates in a 24-hour period. Positive clones can be simultaneously tested for specificity using the
ELISA method. Such automatic, robotic approaches have revolutionized labor-intensive antibody isolation protocols.
Deep sequencing technology is currently being applied to understand the diversity of antibody libraries and to improve the
in vitro selection of antibodies using phage or yeast display. Also, significant information regarding the true diversity of expressed
antibodies among different subsets of B-cells as well as the role of this diversity in disease processes such as lymphoid
cancers, HIV infection, and autoimmune disease is being advanced by carrying out deep sequencing and companion algorithms.
Perhaps the most striking change in antibody strategy is the rise of ADCs. Effective ADCs could profoundly affect the demand
for large quantities of antibodies, since they are effective at a fraction of the dose required by naked antibodies. While
Adcetris has been approved and T-DM1 is expected to enter the market in 2013, both Seattle Genetics and Immunogen have several
more ADCs in their clinical pipeline. Currently, around 100 ADCs are in active development, including 39 in clinical trials.
The pace of research pertaining to the identification of bispecific, bitargeted, and multifunctional antibodies and their
clinical development should allow the introduction of more functionally versatile antibodies. This level of progress will
provide better treatment possibilities for diseases beyond cancer and inflammation, such as those of the central nervous system
and nosocomial infections. While the development of immunomodulatory antibodies, such as Yervoy has been one of the most
significant advances in cancer therapy in the past decade, new and alternative approaches to creating immunomodulatory antibodies
for the treatment of cancer and nonmalignant diseases, including rheumatoid arthritis and multiple sclerosis, will continue
to be vigorously pursued.
The antibody R&D community is also tussling with a variety of challenges, the most pressing of which may be the concept of
the rise of biosimilars and their potential market impact. One way to move beyond this issue is to develop, in some instances,
polyethylene glycol-conjugated (PEGylated) antibodies, which may allow for extension of patent protection. There is a substantial
literature establishing their extended halflife while at the same time retaining their potency and binding ability (6). UCB
Group's Cimzia is a PEGylated anti-TNFα antibody that was approved in 2008 for the treatment of Crohn's disease and rheumatoid
arthritis. The PEGylation method involves expressing antibody fragments in a bacterial system such as Escherichia coli, and then site-specifically PEGylating the fragment in a manner that avoids the loss of antigen-binding activity.
It should be noted that Amunix has developed an alternative technology to PEGylation, called XTENylation that utilizes a long,
hydrophilic, and unstructured amino acid polymer (XTEN). When attached to molecules of interest, it greatly increases their
effective size, thereby prolonging their presence in serum by slowing kidney clearance in a manner analogous to that of PEG.
Because it can be recombinantly engineered into the organism producing an antibody of interest, thereby resulting exceptionally
long half-lives and often monthly dosing of the therapeutic molecule, it offers an alternative to PEG.
Other systems that bear potential promise for generating high-potency products include ultrapotent antibodies produced through
affinity maturation and replacement of crucial amino acids, bispecific antibodies and antibody fragments, glycoengineered
antibodies, and innovative engineering of the Fc portion of the molecule, allowing expanded modifications and novel functions.
While it is always challenging to offer forecasts concerning the future, based upon the late-stage clinical trials of a large
number of antibody therapeutic candidates as well as the recent deal-making activities involving newer antibodies, the authors
believe that both the near- and long-term outlook for the antibody industry is quite positive. Consequently, the authors foresee
the major contribution of antibody therapeutics to pharma revenues should continue.
K. John Morrow, Jr., PhD, is president of Newport Biotechnology Consultants, Newport, KY, and a member of BioPharm International's editorial advisory
, and Rathin C. Das, PhD, is chief executive officer of Synergys Biotherapeutics, Walnut Creek, CA, email@example.com
1. S. Y. Chan et al., Cancer Immunol Immunother.
52 (4), 243–248 (2003).
2. M. J. Smyth et al., Immunol. Cell Biol.
71 (3), 167–79 (1993).
3. S. Verma et al., N. Engl. J. Med.
367 (19), 1783–91 (2012).
4. J. Baselga et al., N. Engl. J. Med.
366 (2), 109–119 (2012).
5. M. A. and G. Gellerman, J Hematol. Oncol.
5, 70–86 (2012).
6. Ducreux et al., Bioconj. Chem.
20 (2), 295–303 (2009).