Generation of a safe and efficacious llama single-domain antibody fragment (vHH) targeting the membrane-proximal region of 4-1BB for engineering therapeutic bispecific antibodies for cancer.
Zhai, T., Wang, C., Xu, Y., Huang, W., Yuan, Z., Wang, T., Dai, S., Peng, S., Pang, T., Jiang, W., Huang, Y., Zou, Y., Xu, Y., Sun, J., Gong, X., Zhang, J., Tsun, A., Li, B., Miao, X.(2021) J Immunother Cancer 9
- PubMed: 34172514 
- DOI: https://doi.org/10.1136/jitc-2020-002131
- Primary Citation of Related Structures:  
7CZD, 7D4B - PubMed Abstract: 
The discovery of checkpoint inhibitors towards cytotoxic T-lymphocyte protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) has been revolutionary for the treatment of cancers. These therapies have only offered an average of 20%-30% response rates across the tumor spectrum and the combination of agonists towards the tumor-necrosis superfamily members, such as 4-1BB and CD40, has shown potent efficacy in preclinical studies; however, these agonists have exhibited high degrees of toxicity with limited efficacy in human trials. In this study, we have generated a single-domain antibody towards a unique epitope of 4-1BB that limits its potential on-target toxicity while maintaining sufficient potency. This 4-1BB binder is ideal for use in the engineering of multispecific antibodies to localize 4-1BB activation within the tumor microenvironment, as shown here by a anti-PD-L1/4-1BB bispecific candidate (PM1003).
Organizational Affiliation: 
Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.