Sartorius #2 eBook - 2019 - 25

Importance of mAb Discovery and Development in Immunotherapy

Recall that the Fc portion of a human antibody is the part of the protein that does
not vary between IgG antibodies. Furthermore, the receptor for the Fc portion (FcRn)
of the antibody is involved in the cellular recycling of the antibody. The constant part
of the antibody, not the epitope recognition area, is bound by the FcRn, which then
endocytoses it into the cell. After processing the antibody within the cell, the recycled
antibody is then moved back to the cell surface, where it is released into the
extracellular space.

"When we compare two different antibodies, we find that late-retention times correlate to short pharmacokinetic half-lives of antibodies. This suggests that immunogenic
therapies with late-eluting antibodies will have to be more frequently dosed or used
with higher doses to be effective," states Dr. Schlothauer. "We [Roche] see this FcRn
column as having very useful applications for extended characterization of drugs, in
addition to screening prospective hits before intensive, expensive development." n

Determining Antibody Half-Life
"This recycling of antibodies is the determining factor in the half-life of antibodies in
the human body," explains Tilman Schlothauer, Ph.D., senior principal scientist at the
Roche Innovation Center Munich. "Having a simple and inexpensive method to evaluate
this characteristic (half-life of an antibody) of a batch of antibodies, or to characterize
a new antibody, is a need faced by drug developers and manufacturers.
Roche's FcRn affinity columns can be used to characterize the binding of therapeutic
immunoglobulin G to FcRn. Biotinylated recombinant human FcRn molecules are
immobilized to a Streptavidin Sepharose matrix and packed into an FPLC column.
"Roche has addressed this desire by developing an affinity separation column that binds
the Fc portion of antibodies. Conditions in the column closely mimic the physiological
interactions of IgG and FcRn."
Changes such as the oxidation state of methionine residues in the Fc portion could
occur during storage. These changes reduce the in vivo half-life of therapeutic antibodies. Two different methionine residues are within the Fc portion of the antibody;
with the homodimer of a complete IgG antibody, therefore, four different loci for
oxidation are present, resulting in a final number of separate species, based on the
oxidation state of the methionine, reaching seven. These species of the oxidized
monoclonal antibodies have different retention times in the FcRn separation column.

25 |

GENengnews.com

Roche's FcRn affinity columns
can be used to characterize the
binding of therapeutic
immunoglobulin G to FcRn.
Biotinylated recombinant
human FcRn molecules are
immobilized to a Streptavidin
Sepharose matrix and packed
into an FPLC column.

http://www.GENengnews.com

Sartorius #2 eBook - 2019

Table of Contents for the Digital Edition of Sartorius #2 eBook - 2019