Figure S1. Synthesis of N188. Figure S2. Mass spectrometry characterization of N188.Figure S3. SPR characterization of N188.Figure S4. Radio-HPLC characterization of 68Ga-N188.Figure S5. Stability of 68Ga-N188 in serum and normal saline. Figure S6. Synthesis of FITC-N188. Figure S7. Mass spectrometry characterization of FITC-N188. Figure S8. Blood routine safety test. Figure S9. Toxicity test of 68Ga-N188. Figure S10. Results of PET/CT dynamic imaging studies in one healthy subject. Figure S11. Pharmacokinetics of 68Ga-N188 in mouse blood. Figure. S12 68Ga-N188 PET/CT imaging with maximum intensity projection (MIP) reconstruction of 12 advanced UC patients with obtained pathological sections. Figure S13. Representative PET/CT images of a patient (No. 3) with advanced urothelial carcinoma. Figure. S14 Comparison of brain metastasis imaging of patient No. 4 using 68Ga-N188, 18F-FDG PET/CT and MRI. Figure. S15 Nectin-4 IHC staining in 12 mUC patients with pathological sections of primary focus.
ARTICLE ABSTRACT
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.
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.
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.
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.See related commentary by Jiang et al., p. 3259
