Evaluation of the biological specificity of the radiopharmaceutical PSMAHBED-CC-⁶⁸Ga in vitro and in vivo tumor models

Diagnostic images in nuclear medicine, obtained with the administration of radiopharmaceuticals, present great advances due to their high specificity and sensitivity, increasing the reliability of the results. This work focused on previous studies based on the ⁶⁸Ga radiolabeled bifunctional chelator associated to PSMA receptor inhibitor peptide, compound that has been shown to be capable of diagnosing prostate cancer recurrences and metastases when used in diagnostic imaging, also assisting in the early diagnosis of the disease. PSMAHBED- CC-⁶⁸Ga radiolabelling studies (non-automated method) were performed to increase the labeling yield, using thin layer chromatography and high performance liquid chromatography for radiochemical purity analyzes, evaluating ⁶⁸GaCl3 eluates from ⁶⁸Ge/⁶⁸Ga generators from different manufacturers. From buffer suitability studies and radiolabelling conditions, a prior formulation was obtained for the development of a ⁶⁸Ga ready-label kit, including the study of the influence of generator eluate quality on labeling yield. For the evaluation of the in vivo biological specificity of the PSMA-HBED-CC- ⁶⁸Ga, biodistribution studies were performed on healthy and tumor-growing animals. Radiopharmaceutical specificity was also evaluated in vitro, with tumor cell binding speed, saturation and competition studies. In vivo and in vitro studies have shown radiopharmaceutical specificity for prostate cancer cells and tumors, contributing to consolidate the preclinical studies required for radiopharmaceutical registration. (author)