www.checkbiotech.org ; www.raupp.info ; www.czu.cz

A novel class of engineered protein, called, single-chain antibodies, can be
produced in plants for therapeutic purposes. Dr. Galeffi and his co-workers,
at ENEA Institute in Casaccia, Italy, reported the production of the
?mini-antibodies? in plants as a promising potential therapy for breast
cancer, October 2006 by Ana Hrus, Checkbiotech.

Cancer cells display a set of proteins on their surface, which are very
specific and not present on normal cells in the same body. Antibodies can
recognize these proteins and bind to them, specifically targeting cancer
cells, while leaving normal tissue intact.

Specificity of a cancer treatment has always been a major concern and
antibody-delivered chemotherapy can greatly reduce unwanted side-effects,
making antibodies very interesting option as a healthcare product.

In some cases a substance can be bound to the antibody, which only becomes
toxic when the antibody binds its target. Once activated, it specifically
kills just the tumor cells, while leaving the healthy cells in the
surrounding tissue intact.

Human epidermal growth factor receptor-2 (HER2) is an oncogene involved in
breast cancer and therefore an important target for antibody therapies.
Several laboratories in the world have developed successful antibodies
against HER-2 antigen.

One of the more innovative approaches stems from Dr. P. Galeffi?s group at
Biotec-Gen, who were able to produce single-chain antibody in plants
(Vaccine).

Antibodies are proteins which specifically recognize a particular molecule
and bind to it. This property is widely applied in diagnostics and even in
therapeutic purposes.

Currently, there is a growing interest in high-yield production of specific
antibodies in plants for therapeutic purposes. Reasons for the interest stem
from reduced costs and the possibility to produce large amounts of specific
substances with minimized risk of immunogenicity once introduced into a
patient.

A novel class of antibodies, single-chain antibodies (scFvs), are a
variation of classical antibodies. They are smaller in size and contain only
a necessary part of an antibody, that specifically recognizes a target of
interest.

?I think that the results from this kind of research can offer an
alternative and good system for drug production, especially in an
application as human oncology,? Dr. Galeffi told Checkbiotech.

Some benefits of scFVs are: they lack the highly immunogenic constant
fragment (Fc), they are cleared from the body more quickly, they are very
specific to the targeted tumor and they can penetrate further into tumors to
ensure it is eliminated.

Traditionally, antibodies like scFvs are produced in microbes such as yeast
or bacteria. However, Dr. Galeffi?s group tried a new approach and produced
them in plants with specificity to HER-2-related breast and ovary human
cancers.

Functional binding of the produced antibody to the antigen present on the
cancer cell surface was tested. No scFv binding was detected with those
cells.

Anti-HER2 antibodies were as well screened for the potential diagnostic
applications. The results from Dr. Galeffi suggest anti-HER2 scFv to be
useful for diagnostic purposes.

Now Dr. Galeffi?s group is taking step to further increase the amount of
antibodies produced by the plants, while also patenting novel production
methods.

Ana Hrus is a Science Journalist for Checkbiotech and is currently finishing
her PhD degree in Cell Biology at the University of Basel, Switzerland.
Contact her at ana.hrus@fmi.ch.

www.checkbiotech.org

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