A stealth-body Fc engineering platform enables complete effector silencing in antibody and ADC therapeutics

The development of next-generation antibody therapeutics requires Fc scaffolds that suppress unwanted effector functions while preserving core developability attributes. Existing effector-attenuated Fc backbones, however, retain residual interactions with Fcγ receptors (FcγRs) and C1q, highlighting a persistent design limitation in achieving complete effector silencing without compromising glycosylation, FcRn-mediated persistence, and manufacturability. This is particularly relevant for formats in which Fc effector function is undesirable, including immune-engaging antibodies, CD47 blockers, and antibody–drug conjugates (ADCs). Accordingly, a robust Fc engineering framework enabling complete and transferable effector silencing across antibody modalities is required. We developed Stealth-Body (SB) Fc variants, a fully effector-silenced Fc platform that abolishes Fc-mediated immune engagem…