KGX-B

KGX-B (also known as co-Dev2 or co-Dev #B) is a discovery-stage protease-activated bispecific T-cell engager (TCE) prodrug (Pro-TCE) being developed by Shanghai Kangkang Biotechnology (KangaBio) for the treatment of small cell lung cancer (SCLC). Utilizing KangaBio's proprietary Pro-TCE platform, the molecule is designed as a masked bispecific antibody targeting CD3 on T cells and an undisclosed tumor-associated antigen (TAA) on cancer cells. The masking domains prevent systemic T-cell activation and on-target, off-tumor toxicities in healthy tissues. Upon entering the protease-rich tumor microenvironment, tumor-specific proteases cleave the linkers, releasing the masks and conditionally activating the T-cell engager to recruit and activate T cells specifically within the tumor. KGX-B is currently in the discovery phase of development, with clinical entry projected for 2028.