Rational design of a common-light-chain bispecific antibody unlocks broad antitumor activity

Tyrosine kinase inhibitors (TKIs) targeting the epidermal growth factor receptor (EGFR) have transformed the treatment of EGFR-mutant non-small cell lung cancer (NSCLC). However, acquired resistance is almost inevitable, with amplification of the MET proto-oncogene being the most common bypass mechanism. This amplification reactivates downstream survival pathways, rendering EGFR inhibition ineffective. Co-targeting EGFR and c-MET with a single bispecific antibody has emerged as a clinically validated strategy, exemplified by amivantamab. However, engineering such molecules remains slow and resource-intensive.

In a study published in hLife, researchers from the Institute of Microbiology, Chinese Academy of Sciences, Changping Laboratory, and Shanghai Allink Biotherapeutics developed a structure-guided rational design workflow for bispecific antibody development. This strategy enables existing monoclonal antibodies to be converted into common-light-chain bispecific antibodies (BsAbs), even when the light chain directly contributes to antigen recognition. Using this workflow, the team generated ALK101, an EGFR×c-MET BsAb with binding affinity, ligand-blocking activity, kinase-inhibitory activity, and receptor-internalization activity comparable to those of amivantamab, the current clinical benchmark. Its potency values were generally within two-fold of those of amivantamab.

“Conventional bispecific antibody development relies on large-scale library screening or transgenic animal platforms, processes that can take years. Our structure-guided method reduces this process to a few focused rounds of engineering and could, in principle, be applied to many other target combinations,” said Li Li, corresponding author of the study.

The team began by comparing the structures of known anti-EGFR and anti-c-MET antibodies. They identified a key obstacle to using a single shared light chain to recognize both antigens: several critical residues were incompatible with binding to the second target. Targeted back-mutations and saturation mutagenesis helped optimize the light chain, while affinity maturation of the heavy chain restored the hydrogen-bond network required for EGFR binding. Crystal structures of ALK101 in complex with each antigen confirmed that these compensatory mutations preserved the parental binding geometry.

In mouse xenograft models, ALK101 achieved potent, dose-dependent tumor suppression, including against tumors harboring triple mutations associated with resistance to first-, second-, and third-generation TKIs. ALK101 also showed an additive effect when combined with osimertinib (combination index Q = 1.13). In cynomolgus monkeys, subcutaneous administration of ALK101 resulted in 89% bioavailability, with a no-observed-adverse-effect level (NOAEL) of 120 mg/kg.

Because the design framework is not limited to a specific antigen pair, it offers a potentially generalizable and more efficient approach to bispecific antibody development in oncology and other therapeutic areas. For ALK101, the pharmacokinetic and safety data support its further development as a potential treatment option for patients with TKI-resistant lung cancer. However, its efficacy and safety have so far been evaluated only in preclinical models and remain to be validated in human trials.

This study was conducted by researchers from the Institute of Microbiology, Chinese Academy of Sciences; Changping Laboratory; and Shanghai Allink Biotherapeutics Co., Ltd. The authors declared that they received no specific funding for this research from public, commercial, or not-for-profit funding agencies.

About Author:

Jinghua Yan is a corresponding author of this study and a researcher at Changping Laboratory, Beijing, China. Her research interests include therapeutic antibody discovery, molecular immunology, and translational research in oncology.

Li Li is a corresponding author of this study and a researcher at Shanghai Allink Biotherapeutics Co., Ltd., Shanghai, China, where his work focuses on the discovery and engineering of therapeutic bispecific antibodies for cancer treatment.

Hui Feng is a corresponding author of this study and a researcher at Shanghai Allink Biotherapeutics Co., Ltd., Shanghai, China. His research focuses on antibody drug development, biologics manufacturing, and the translation of preclinical antibody candidates into clinical-stage therapeutics.

DOI Link:

https://doi.org/10.1016/j.hlife.2026.08.003