First-in-Human Safety and Dosimetry Study of ¹⁷⁷Lu-FAPI in Patients With FAP-Positive Malignancies

Cancer-associated fibroblasts (CAFs) constitute a critical component of the tumor microenvironment and are widely distributed in the stroma of various malignancies. Fibroblast activation protein (FAP), a specific biomarker of CAFs, is overexpressed in more than 90% of malignant tumors but exhibits limited expression in normal tissues, rendering it an ideal target for the diagnosis and treatment of multiple cancers. To date, a variety of FAP-targeted radiopharmaceuticals have been developed for radionuclide therapy, such as 177Lu-FAPI-46 and 177Lu-FAP-2286. These agents have demonstrated potent anti-tumor efficacy and a favorable toxicity profile in oncological treatment. The novel radiopharmaceutical 177Lu-JH040182 also exhibits excellent in vitro and in vivo stability. Preclinical investigations have validated its high binding affinity, favorable safety profile and outstanding tumor selectivity, enabling specific accumulation within neoplastic tissues.

This study aimed to evaluate the dosimetric effects, toxicities and therapeutic efficacy of 177Lu-JH040182 in patients with advanced metastatic cancers who failed all prior therapeutic regimens without meaningful clinical improvement. Eligible patients first underwent 68Ga-FAPI PET/CT to confirm FAP-positive lesions (defined as >50% of lesions with an SUVmax exceeding 10). Upon confirmation, patients received intravenous administration of 177Lu-JH040182 at a radioactivity dose ranging from 5.55 to 7.40 GBq. Serial SPECT imaging was subsequently performed at multiple time points for each subject, and the absorbed doses to tumor lesions and normal physiological organs were quantified using the Hermes system software.