AT-03

**AT-03** is an investigational **recombinant fusion protein** originally referred to as **SAP-scFc**, developed by **Attralus** for **systemic amyloidosis**. It consists of **serum amyloid P-component** fused to a **single-chain human IgG1 Fc domain**. The SAP portion is designed to bind broadly to amyloid deposits across multiple amyloid types, while the Fc domain is intended to recruit phagocytic immune effector function and promote **macrophage-mediated opsonization and clearance of deposited amyloid**. Preclinical reports describe pan-amyloid binding to AL, ATTR, AA, and AApoA2 amyloid, including cardiac deposits, with reduction of splenic amyloid in an AA mouse model after intravenous dosing. AT-03 is positioned as a first-in-class pan-amyloid removal therapeutic rather than a fibril production inhibitor, with development focused on organ amyloid removal in systemic amyloidosis.

Other names

serum amyloid P-component single-chain Fc fusion protein