<sup>68</sup>Ga/<sup>177</sup>Lu-Labeled Theranostic Pair for Targeting Fibroblast Activation Protein with Improved Tumor Uptake and Retention
Jiawen Huang, Xiaojun Zhang, Qingxing Liu, Fengping Gong, Yanchao Huang, Shun Huang, Lilan Fu, Ganghua Tang
Abstract
Fibroblast activation protein (FAP) is specifically expressed on cancer-associated fibroblasts in over 90% of tumors and is considered a promising target for cancer theranostics. Here, we developed a novel tracer, DOTA-FAPT, and labeled it with gallium-68 and lutetium-177 as a theranostic pair. [ 68 Ga]Ga/[ 177 Lu]Lu-FAPT exhibited high stability and hydrophilicity, as well as strong affinity to the FAP target. Micro-PET/CT imaging revealed that [ 68 Ga]Ga-FAPT exhibited significantly increased uptake in tumors and extended retention in A549-FAP and U87MG tumor xenografts as compared to [ 68 Ga]Ga-FAPI-04, demonstrating favorable pharmacokinetic characteristics in vivo. Therapeutic studies showed that [ 177 Lu]Lu-FAPT had higher tumor accumulation compared to [ 177 Lu]Lu-FAPI-04, leading to stronger tumor growth inhibition. The first-in-human evaluation also revealed that [ 68 Ga]Ga-FAPT has good in vivo distribution and superior diagnostic efficacy on primary and lymph node metastases in a patient with lung cancer. Our encouraging results suggest that 68 Ga/ 177 Lu-labeled DOTA-FAPT is a theranostic pair with broad application prospect.