1
Antibody-Drug Conjugates
(ADCs)
Application Note NT-MO-027
Studying the interaction of the antibody-drug conjugate
SYD985 with an anti-toxin antibody
Moran Jerabek-Willemsen
1
, David Egging
2
1
NanoTemper Technologies GmbH, Munich, Germany
2
Synthon Biopharmaceuticals B.V.
Abstract
Antibody-drug conjugates (ADCs) have been
recognized as a promising new class of
therapeutic agents for the treatment of cancer
(1). In the generation of ADCs, cytotoxic small
molecules are covalently attached to
therapeutic antibodies thereby increasing their
tumor cell killing capability. We have
performed MicroScale Thermophoresis
experiments to determine the K
d
values for the
interaction between fluorescently labeled
antibody-drug conjugate (SYD985) and an anti-
toxin (drug) antibody in phosphate buffer as
well in human plasma. The data show that
MicroScale Thermophoresis is a powerful tool
for the study of antibody-antigen interactions
in standard buffers as well as complex
bioliquids.
Introduction
SYD985 is an antibody drug conjugate composed
of the monoclonal IgG1 antibody trastuzumab
(SYD977) covalently bound to a linker-drug. The
linker-drug contains a cleavable linker and the
prodrug seco-duocarmycin-hydroxybenzamide-
azaindole (seco-DUBA). The linker can be cleaved
by proteases in the tumor cells at the dipeptide
valine-citrulline (vc), which releases the active
toxin (Figure 1).
Here, we show the use of MicroScale
Thermophoresis (MST) (2) to analyze the
interaction of the ADC (SYD985) with a specific
mouse monoclonal anti-toxin antibody. In addition
we have determined the binding affinity in 50 %
human plasma as well.
Figure 1. Mechanism of activation of SYD985 inside the
tumor cell to release the toxic duocarmycin drug. When
SYD985 has been taken up into the tumor cell by endocytosis
the linker is cleaved in the lysosome by proteases such as
cathepsin B. Subsequently, an engineered domino-reaction
occurs to generate the seco-DUBA, which then spontaneously
rearranges to form the activated duocarmycin drug. This can
then bind and alkylate DNA, finally resulting in cell death.