Feasibility, Tolerability, and Preliminary Clinical Response of Fractionated Radiopharmaceutical Therapy with ²¹³Bi-FAPI-46: Pilot Experience in Patients with End-Stage, Progressive Metastatic Tumors

Radiopharmaceutical therapies (RPTs) based on fibroblast activation protein (FAP) and FAP inhibitors (FAPIs) are a new option for progressive metastatic cancer in patients pretreated multiple times. To date, published in-human data refer to initial experiences with β-emitting ^(90)Y- and ^(177)Lu-based RPT. However, the short tumor retention time of FAPI ligands is considered a major limitation of FAPI RPT. Therefore, fractionated FAPI RPT with ^(213)Bi, an α-emitter with a half-life of 46 …