Cumulated activity comparison of 64Cu-/177Lu-labeled anti-epidermal growth factor receptor antibody in esophageal squamous cell carcinoma model

Abstract

This work aimed at estimating the kinetic parameters, and hence cumulated activity (AC), of a diagnostic/therapeutic convergence radiopharmaceutical, namely 64Cu-/177Lu-labeled antibody (64Cu-/177Lucetuximab), that acts as anti-epidermal growth factor receptor. Methods: In mice bearing esophageal squamous cell carcinoma tumors, to estimate uptake (K), release rate constant (kR), and hence AC, a kinetic model analysis was applied to recently published biodistribution data of immuno-PET imaging with 64Cu-cetuximab and of small-animal SPECT/CT imaging with 177Lu-cetuximab, including blood and TE-8 tumor. Results: K, kR, and AC were estimated to be 0.0566/0.0593 gh21g21, 0.0150/0.0030 h21, and 2.3 1010/4.1 1012 disintegrations (per gram of TE-8 tumor), with an injected activity of 3.70/12.95 MBq, for 64Cu-/177Lu-cetuximab, respectively. Conclusion: A model is available for comparing kinetic parameters and AC of the companion diagnostic/therapeutic 64Cu-/177Lu-cetuximab that may be considered as a step for determining whether one can really use the former to predict dosimetry of the latter.