First-in-Human Study of the Radioligand 68Ga-N188 Targeting Nectin-4 for PET/CT Imaging of Advanced Urothelial Carcinoma

Purpose: Nectin-4 is an emerging biomarker for cancer diagnosis and therapy. Recently, enfortumab vedotin (EV) was approved by the FDA as the first nectin-4 targeting antibody–drug conjugate for treating advanced urothelial carcinoma (UC). A PET imaging method to noninvasively quantify nectin-4 expression level would potentially help to select patients most likely to respond to EV and predict the response. Experimental Design: In this study, we designed a bicyclic peptide-based nectin-4 targeting radiotracer 68Ga-N188. Initially, we performed preclinical evaluations of 68Ga-N188 in UC cell lines and xenograft mouse models. Next, we performed the translational study in healthy volunteers and a pilot cohort of patients with advanced UC on uEXPLORER total-body PET/CT. Results: In the preclinical study, 68Ga-N188 showed high affinity to nectin-4, specific uptake in a nectin-4(+) xenograft mouse model, and suitable pharmacokinetic and safety profiles. In the translational study, 2 healthy volunteers and 14 patients with advanced UC were enrolled. The pharmacokinetic profile was determined for 68Ga-N188, and the nectin-4 relative expression level in different organs was quantitatively imaged. Conclusions: A clear correlation between PET SUV value and nectin-4 expression was observed, supporting the application of 68Ga-N188 PET as a companion diagnostic tool for optimizing treatments that target nectin-4.