CD3E and neoplasm: Notable features of TFAB002s include (i) a head-to-tail fusion via a flexible linker between the CD20- and CD3ε-binding Fab domains, ensuring potent binding avidity towards tumor cells while limiting affinity towards T cells, (ii) conditional T-cell activation dependent on the presence of target cells, (iii) closer immune synapse formation, and (iv) an engineered CH3 domain with knob-into-hole technology instead of the CH1-CL domain, which confers an extended half-life but abolishes its binding to complement component (C1q) and to Fc gamma receptors (FcγR).