sodium-pertechnetate-tc-99m and Carcinoma--Ehrlich-Tumor

A quick and reproducible method for radiolabeling of Photosan-3(R), a photosensitizer used worldwide for photodynamic therapy (PDT) of cancer, with radioisotope of technetium ((99m)Tc) was developed. The radiotracer was evaluated for radiochemical purity, stability, and finally tissue distribution in a murine tumor model. The (99m)Tc-Photosan-3 prepared by using (99m)Tc-pertechnetate in place of reduced (99m)Tc demonstrated better labeling efficiency (>90%) and reproducibility. The procedure also minimized the radiation exposure to the radiochemist as handling time was considerably reduced. Due to the commercial availability of Photosan-3, the risk of batch-to-batch variation in the in situ synthesis of hematoporphyrin derivative, which is a complex mixture of at least five compounds, was also significantly reduced. The biodistribution studies and tumor scintigraphy confirmed that (99m)Tc-labeled Photosan-3 was preferentially taken up by the neoplastic tissue in a manner similar to the parent compound. In addition to applications in tumor imaging, (99m)Tc-Photosan-3 could also be used for estimating tumor uptake of Photosan-3 as may be required for individualization of clinical protocols of PDT.

Topics: Animals; Carcinoma, Ehrlich Tumor; Disease Models, Animal; Drug Evaluation, Preclinical; Drug Stability; Hematoporphyrins; Metabolic Clearance Rate; Mice; Neoplasm Transplantation; Organ Specificity; Photosensitizing Agents; Rabbits; Radionuclide Imaging; Radiopharmaceuticals; Reproducibility of Results; Sodium Pertechnetate Tc 99m; Technetium; Tin Compounds; Tissue Distribution