HWK-206 is an advanced antibody-drug conjugate utilizing a novel biparatopic targeting strategy directed against SEZ6, a protein frequently overexpressed in small cell lung cancer and various neuroendocrine tumors. By binding to two distinct epitopes on the same target simultaneously via an engineered Fc-attenuated IgG1 framework, the molecule enhances receptor internalization, optimizes intracellular payload delivery, and demonstrates powerful tumor cell-killing capabilities while minimizing systemic toxicity risks.