Lutetium Lu 177 XT117

**Semantic type:** Pharmacologic Substance

**Definition:** A radioconjugate composed of XT117, a fibroblast activation protein inhibitor (FAPi), conjugated to the beta-emitting radioisotope lutetium Lu 177 (177Lu), with potential antineoplastic activity against FAP-expressing cancer-associated fibroblasts (CAFs). Upon administration, lutetium Lu 177 XT117 targets and binds to FAP-expressing CAFs. Upon binding, FAP-expressing CAFs are destroyed by 177Lu through the specific delivery of beta particle radiation. FAP, a cell surface protein, is overexpressed on CAFs in the tumor microenvironment (TME) of various cancers.

**Synonyms:** - 177Lu-labeled XT117 - Lu-177-XT117 - [177Lu]Lu-XT117