Burley TA, et al. - In this investigation, researchers tested the premise that imaging with epidermal growth factor receptor 1 (EGFR)-specific radioligands can facilitate noninvasive measurement of EGFR expression across the entire tumor burden and enable dynamic monitoring of cetuximab-mediated changes in receptor expression. EGFR-specific Affibody molecule (Z_EGFR:03115) was radiolabeled with ⁸⁹Zr and ¹⁸F. By immunohistochemistry, Western blot, and autoradiography, the EGFR expression and biodistribution of the tracer were assessed ex vivo. There was a strong association between PET analysis, ex vivo estimates of tracer concentration, and receptor expression in tumor tissues. According to findings, Z_EGFR:03115-based radioconjugates can evaluate various levels of EGFR level in vivo and assess receptor expression changes in response to cetuximab, showing potential for assessing satisfactory treatment dosing with anti-EGFR antibodies.