Definition

A conditionally active biologic (CAB) and bispecific antibody directed against both the tumor-associated antigen (TAA) human epithelial cell adhesion molecule (Ep-CAM; EpCAM; CD326) and T-cell surface glycoprotein CD3 epsilon chain (CD3E), with potential immunomodulating and antineoplastic activities. Upon administration and specific activation in the tumor microenvironment (TME), anti-EpCAM/anti-CD3 bispecific antibody BA3182 targets and binds to both EpCAM on EpCAM-expressing tumor cells and CD3E on cytotoxic T lymphocytes (CTLs) within the TME. This activates and redirects CTLs to EpCAM-expressing tumor cells, which results in the CTL-mediated cell death of EpCAM-expressing tumor cells. EpCAM, a cell surface protein upregulated on many tumor cell types, promotes the proliferation, migration and invasiveness of tumor cells. Negatively charged, physiologically-occurring molecules interact with positively charged areas on the protein surface to prevent the activation of BA3182 outside the TME. In the acidic TME, the negatively charged molecules are neutralized and released, allowing the binding to EpCAM and CD3E. This may reduce systemic toxicity.