Vipivotide tetraxetan (also known as PSMA-617) is a radiopharmaceutical precursor molecule used in targeted therapies for prostate cancer and other tumors expressing prostate-specific membrane antigen (PSMA).
PSMA-617 is a high-affinity inhibitor of the peptidase activity of PSMA, with a K<sub>i</sub> of 0.37 nM. It consists of a PSMA-targeting moiety conjugated to a high-affinity chelator for metal isotopes. Its strong binding affinity for PSMA allows precise targeting of cancer cells that overexpress this protein, especially in prostate cancer.
Vipivotide tetraxetan is used as a precursor in the synthesis of radiopharmaceuticals such as Lu-PSMA-617 and Ac-PSMA-617. In Lu-PSMA-617, vipivotide tetraxetan chelates the radioactive isotope lutetium-177, a ò-emitter used in targeted radioligand therapy. In Ac-PSMA-617, it binds actinium-225, an ñ-emitter used in targeted alpha-particle therapy.
The compound's structure includes a PSMA-binding motif (Lys-urea-Glu), a hydrophobic linker (composed of 2-naphthyl-l-Ala and cyclohexyl groups), and a DOTA chelator for radiolabeling.
Vipivotide tetraxetan is the International Nonproprietary Name (INN) and United States Adopted Name (USAN) for the ligand-targeting and metal-chelating components, respectively, of the radiopharmaceutical drugs Lu-PSMA-617 and Ac-PSMA-617.
"Vipivotide" refers to the peptide-based targeting moiety (Lys-urea-Glu) that binds specifically to prostate-specific membrane antigen (PSMA) on prostate cancer cells. The suffix "tide" denotes the peptide nature of this moiety.
"Tetraxetan" refers to the chelator moiety, a chemical group that binds metal ions within the molecule. The name "tetraxetan" is derived from "tetraazacyclododecane tetra-acetic acid" (DOTA), a well-known macrocyclic chelator that securely holds the radioactive isotope in the drug. The "tetra-" prefix indicates the four nitrogen atoms in the macrocycle and the four acetic acid arms in the DOTA structure, while "xetan" is a standard suffix for chelators.