CTSB and neoplasm: Structure‐activity relationship (SAR) studies have demonstrated that even minor modifications to diABZI‐based STING agonists (e.g., morpholine substitution to form a quaternary ammonium salt) can significantly enhance solubility without requiring complex polysaccharide modifications.[21] Furthermore, this modification renders dSA3 prodrug‐like, masking its pharmacological activity until tumor‐localized lysosomal cleavage (e.g., by cathepsin B) releases the payload, minimizing off‐target effects and broadening the therapeutic window.