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Published on: May 20, 2020
Affinity Maturation of an Epidermal Growth Factor Receptor Targeting Human Monoclonal Antibody ER414 by CDR Mutation
Ki-Hwan Chang1, Min-Soo Kim, Gwang-Won Hong
1Antibody Engineering Lab., Green Cross Research Center, Green Cross Corp., Yongin 446-770, Korea.
Abstract:
It is well established that blocking the interaction of EGFR with growth factors leads to the arrest of tumor growth, resulting in tumor cell death. ER414 is a human monoclonal antibody (mAb) derived by guided selection of the mouse mAb A13. The ER414 exhibited a ~17-fold lower affinity and, as a result, lower efficacy of inhibition of the EGF-mediated tyrosine phosphorylation of EGFR when compared with mAb A13 and cetuximab. We performed a stepwise in vitro affinity maturation to improve the affinity of ER414. We obtained a 3D model of ER414 to identify the amino acids in the CDRs that needed to be mutated. Clones were selected from the phage library with randomized amino acids in the CDRs and substitution of amino acids in the HCDR3 and LCDR1 of ER414 led to improved affinity. A clone, H3-14, with a ~20-fold increased affinity, was selected from the HCDR3 randomized library. Then three clones, ER2, ER78 and ER79, were selected from the LCDR1 randomized library based on the H3-14 but did not show further increased affinities compared to that of H3-14. Of the three, ER2 was chosen for further characterization due to its better expression than others. We successfully performed affinity maturation of ER414 and obtained antibodies with a similar affinity as cetuximab. And antibody from an affinity maturation inhibits the EGF-mediated tyrosine phosphorylation of EGFR in a manner similar to cetuximab.
Insights
Researchers enhanced ER414, a human monoclonal antibody, to improve its binding affinity for EGFR. Affinity maturation successfully created antibodies with efficacy comparable to cetuximab, offering new therapeutic potential for cancer treatment.
Area of Science:
- Biotechnology
- Immunology
- Oncology
Background:
- Epidermal Growth Factor Receptor (EGFR) signaling is crucial for tumor growth.
- Monoclonal antibodies (mAbs) targeting EGFR, like cetuximab, are established cancer therapies.
- ER414, a human mAb, showed lower efficacy than cetuximab in inhibiting EGFR phosphorylation.
Purpose of the Study:
- To improve the binding affinity and efficacy of the ER414 antibody through in vitro affinity maturation.
- To generate novel EGFR-targeting antibodies with therapeutic potential.
Main Methods:
- Utilized a 3D structural model of ER414 to guide mutations in Complementarity-Determining Regions (CDRs).
- Employed phage display technology with randomized amino acids in CDRs (HCDR3 and LCDR1) for affinity maturation.
- Selected and characterized high-affinity clones, including H3-14 and ER2.
Main Results:
- Affinity maturation significantly increased the binding affinity of ER414, with clone H3-14 showing a ~20-fold improvement.
- Selected clones, particularly ER2, demonstrated comparable affinity to cetuximab.
- The affinity-matured antibody inhibited EGF-mediated EGFR tyrosine phosphorylation similarly to cetuximab.
Conclusions:
- Successful in vitro affinity maturation of ER414 yielded antibodies with enhanced binding affinity and efficacy.
- The developed antibodies represent promising candidates for EGFR-targeted cancer therapy.
- This strategy provides a pathway for optimizing antibody therapeutics.
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