[177Lu]Lu-AKY-2519

[177Lu]Lu-AKY-2519 is a lutetium-177-labeled targeted miniprotein radioconjugate developed by Aktis Oncology. It is designed to target the B7-H3 (CD276) antigen, a transmembrane protein frequently overexpressed in various solid tumors, including metastatic castration-resistant prostate cancer (mCRPC). Within the AKY-2519 theranostic program, the lutetium-177 variant is utilized primarily as an imaging and dosimetry surrogate. Administered at low, non-therapeutic doses, it allows for the evaluation of biodistribution and the estimation of absorbed radiation doses to inform the development of the intended therapeutic agent, [225Ac]Ac-AKY-2519. The miniprotein scaffold is engineered to provide high tumor uptake and prolonged retention while maintaining rapid systemic clearance. Early clinical data from first-in-human studies indicate robust tumor uptake for at least six days post-administration and a favorable safety profile.