Anti-Human EGFR Recombinant Antibody (Matuzumab) (CAT#: TAB-165)

Figure 1 Characterization of the EGFR-Binding and Ligand Competition Properties of Matuzumab.

(A) Surface Plasmon Resonance (SPR) analysis of the binding of sEGFR and sEGFRd3 to immobilized Fab72000 (the antigen-binding domain of matuzumab). A series of samples of sEGFR or sEGFRd3, at the indicated concentrations, was passed over a biosensor surface to which Fab72000 had been amine coupled. Data points show the equilibrium SPR response value for a representative set of samples of sEGFR (black squares) and of sEGFRd3 (open triangles), expressed as a percentage of the maximal SPR-binding response. The curves represent the fit of these data to a simple one-site Langmuir binding equation. KD values, based on at least three independent binding experiments, are 113 ± 25 nM for sEGFR and 43 ± 13 nM for sEGFRd3.
(B) Competition of EGF (green diamonds), matuzumab (red triangles), or cetuximab (black triangles) for the binding of 125I-labeled EGF to A431 cells. Cells were incubated with media containing 3 nM 125I-labeled EGF plus the indicated concentration of cold matuzumab, cetuximab, or EGF for 6 hr at 4°C. Following washing to remove unbound material, cells were lysed and liquid scintillation counting was used to determine the amount of bound 125I-labeled EGF. The counts per minute (CPM) for each sample are shown, expressed as a percentage of the CPM value obtained for no added competitor. Error bars indicate the standard deviation on three independent experiments. The line indicates the fit to a sigmoidal dose-response model. IC50 values from this analysis are 2.0 nM for matuzumab and cetuximab and 7.3 nM for EGF.

Schmiedel, J., Blaukat, A., Li, S., Knöchel, T., & Ferguson, K. M. (2008). Matuzumab binding to EGFR prevents the conformational rearrangement required for dimerization. Cancer cell, 13(4), 365-373.

Figure 2 Implications for the Mechanism of Inhibition of EGFR by Matuzumab.

(A) Cartoon of the extended sEGFR with Fab72000, in surface representation, docked onto its domain III epitope. The orientation of the receptor is the same as for the right-hand protomer in the sEGFR dimer shown in Figure 1 (with domains colored as for the left-hand protomer; EGF is omitted for clarity). The Fab72000 is colored as in Figure 3. The N-terminal region of domain I clashes with the VL domain (indicated with an arrow). Additional clashes occur along the C-terminal half of domain II (see [B]). The C-terminal loop on domain II (D278, H280) that makes critical contacts across the dimer interface is marked with an asterisk.
(B) In this view, an approximate 50° rotation about the vertical axis relative to (A), domain II is shown in sphere representation in dark green. A cartoon of domain II of the other molecule in the dimer is shown (light green) for reference. Domain I has been omitted for clarity. The VL domain of the Fab clashes with domain II in the critical C-terminal region that forms the binding pocket for the dimerization arm and makes important contacts with domain III (from N274 and E293 in domain II, colored orange). These interactions are known to be crucial for stabilizing the dimerization competent conformation of domain II. The Fab72000 epitope loop on domain III is colored in red.

Schmiedel, J., Blaukat, A., Li, S., Knöchel, T., & Ferguson, K. M. (2008). Matuzumab binding to EGFR prevents the conformational rearrangement required for dimerization. Cancer cell, 13(4), 365-373.

Figure 3 FACS analysis of REAL-Select enrichment of matuzumab-displaying cells.

Functionalized yeast cells displaying (A) matuzumab or (B) trastuzumab were mixed 1∶1,000,000 (C) and labeled using EGFR-PE and goat-anti-Fc F(ab′)2 AlexaFluor647. (C,D) FACS analysis of the cell population of sorting round 1 (C) and 4 (D) of FACS enrichment of matuzumab displaying cells.

Rhiel, L., Krah, S., Günther, R., Becker, S., Kolmar, H., & Hock, B. (2014). REAL-Select: full-length antibody display and library screening by surface capture on yeast cells. PloS one, 9(12), e114887.

Figure 4 Binding of mAbs cetuximab and matuzumab to peptide arrays.

Left: Triplicate samples of EGFR-expressing Renca-lacZ/EGFR renal carcinoma cells were treated with scFv(225)-ETA antibody-Pseudomonas exotoxin A fusion protein after preincubation of antibody-toxin with a 100-fold molar excess of synthetic peptides VLPKTLCGGGS (KTL motif) or ACKYPLGHQCGGGS (YPLG motif) as described in Supplementary Methods. Control cells were treated without antibody-toxin, with toxin without competitor (PBS) or with the irrelevant peptide SFLQDIQEV (control) as competitor. Right: Specificity was confirmed in similar experiments with ErbB2-specific scFv(FRP5)-ETA antibody-toxin and ErbB2-expressing Renca-lacZ/ErbB2 cells. The relative number of viable cells was determined after 48 h in MTT cell viability assays. Representative data from one of two independent experiments are shown. Statistically significant differences are indicated. ***P <0.001; NS, P>0.05. Data are represented as mean±s.d. Binding of mAbs cetuximab and matuzumab to synthetic peptides VLPKTLCGGGS (left) and ACKYPLGHQCGGGS (right) was measured by ELISA by adding serial dilutions of cetuximab, matuzumab or anti-ErbB2 mAb trastuzumab as control to triplicate samples of immobilized peptides.

Hartmann, C., Müller, N., Blaukat, A., Koch, J., Benhar, I., & Wels, W. S. (2010). Peptide mimotopes recognized by antibodies cetuximab and matuzumab induce a functionally equivalent anti-EGFR immune response. Oncogene, 29(32), 4517.

Figure 5 Anti-peptide antibodies bind to the surface of EGFR-expressing cells.

Control cells were incubated with matuzumab, pre-immune rabbit serum or anti-peptide antibodies pretreated with a 40-fold molar excess of specific peptide as indicated. Bound antibodies were detected with FITC-conjugated anti-rabbit IgG (anti-peptide antibodies) or anti-human IgG (matuzumab). Cell bodies were visualized by staining with an excess of propidium iodide (PI). For colocalization studies, Renca-lacZ/EGFR cells were simultaneously incubated with affinity-purified rabbit anti-KTL or anti-YPLG peptide antibodies (the latter generated by immunization with peptide ACKYPLGHQCGGGS) or pre-immune rabbit serum as control, and murine anti-EGFR mAb R1.

Hartmann, C., Müller, N., Blaukat, A., Koch, J., Benhar, I., & Wels, W. S. (2010). Peptide mimotopes recognized by antibodies cetuximab and matuzumab induce a functionally equivalent anti-EGFR immune response. Oncogene, 29(32), 4517.

Figure 6 Anti-peptide antibodies bind to the surface of EGFR-expressing cells.

Triplicate samples of A431 and MDA-MB468 cells were incubated with 50 μg/ml of anti-KTL or anti-YPLG peptide antibodies, or matuzumab, trastuzumab or pre-immune serum as indicated. The relative number of viable cells in comparison to PBS-treated controls was determined after 70 h in MTT cell viability assays. Representative data from one of two independent experiments are shown. Statistically significant differences between PBS-treated group and groups treated with antibodies are indicated. ***P<0.001; **P<0.01; NS, P>0.05. Data are represented as mean±s.d.

Hartmann, C., Müller, N., Blaukat, A., Koch, J., Benhar, I., & Wels, W. S. (2010). Peptide mimotopes recognized by antibodies cetuximab and matuzumab induce a functionally equivalent anti-EGFR immune response. Oncogene, 29(32), 4517.