TB202-63

TB202-63 is a single-domain VHH nanobody-based monoclonal antibody directed against the receptor-binding domain (RBD) of the SARS-CoV-2 spike (S) protein, developed by Twist Bioscience as a potential COVID-19 therapeutic. Derived from large synthetic llama-inspired VHH libraries, TB202-63 binds the S1 RBD with nanomolar affinity and blocks its interaction with the ACE2 receptor, thereby preventing viral entry into host cells.[1][4] In vitro it potently neutralizes SARS-CoV-2, including pseudovirions bearing the Beta (B.1.351) variant spike, and in preclinical hamster challenge models TB202-63 formulated as a VHH-Fc protects against weight loss and reduces disease severity at doses as low as 1 mg/kg, both alone and in combination antibody cocktails.[1][4][5][6][7]