Page 77 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

4.2 Antibody based targeted therapy 75

therapy is selectivity, in other words, the ability to detect and remove tumor cells and
destroy them without damaging normal cells; this method has been highly respected
by researchers.

4.2.1 The mechanism of antibody based targeted therapy
Antibodies exhibit therapeutic effects by targeting the surface expressed antigens on
cancer cells (Fig. 4.1). Before investigating the mechanisms of antibody activity on
cancer cells, it is necessary to briefly describe their characteristics, while we were
covered them in detail in the previous sections.
Antibodies, commonly used in form of immunoglobulins, are proteins that have
two binding arms. Antigen-binding portion and Fc-region that is responsible for
binding to serum proteins (complement) or cells. The use of antibodies for treatment
of cancer is divided into two general methods:

- An antibody directly and by alterations in intracellular signaling or inhibition
of function of growth factor receptors or inhibition of function of adhesion
molecules causes tumor cell apoptosis [13].
- Antibody itself does not have the responsibility to kill the target cells, but
instead marks the target cells that other components or effector cells of the
body’s immune system can attack the cell. The mechanisms for attacking the
labeled cells with the antibodies are made from two paths:
- Antibody dependent cellular cytotoxicity (ADCC)
- Antibody-dependent complement mediated cytotoxicity (CMC)
ADCC includes the identification of the antibodies by immune system cells that
interact with antibody marked cells directly or through other cells (Fig. 4.2). And
CMC is a process in which different complement proteins act as cascades; it usually
happens when there are several immunoglobulins in close proximity to each other
that either directly lead to cell lysis or indirectly invoke other immune system cells
to this location [14].

FIGURE 4.1 The mechanism of antibody based targeted therapy.