title: Evaluation of (99m)Tc-labeled photosan-3, a hematoporphyrin derivative, as a potential radiopharmaceutical for tumor scintigraphy.
abstract: 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.
authors.affiliation: Department of Radiopharmaceuticals, Institute of Nuclear Medicine and Allied Sciences, Lucknow Marg, Delhi, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Babbar
authors.forename: A K
authors.initials: AK
authors.lastname: Singh
authors.forename: H C
authors.initials: HC
authors.lastname: Goel
authors.forename: U P
authors.initials: UP
authors.lastname: Chauhan
authors.forename: R K
authors.initials: RK
authors.lastname: Sharma
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000000981:diagnostic imaging* / Q000378:metabolism; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D004355:Drug Stability; D006415:Hematoporphyrins / Q000737:chemistry / Q000493:pharmacokinetics; D008657:Metabolic Clearance Rate; D051379:Mice; D009368:Neoplasm Transplantation; D009928:Organ Specificity; D017319:Photosensitizing Agents / Q000737:chemistry / Q000493:pharmacokinetics; D011817:Rabbits; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000737:chemistry / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D013670:Sodium Pertechnetate Tc 99m / Q000737:chemistry; D013667:Technetium / Q000032:analysis / Q000737:chemistry*; D017971:Tin Compounds / Q000737:chemistry; D014018:Tissue Distribution
chemical_list: D006415:Hematoporphyrins; D017319:Photosensitizing Agents; D019275:Radiopharmaceuticals; D017971:Tin Compounds; C071875:photosan III; C023599:stannous chloride; D013667:Technetium; D013670:Sodium Pertechnetate Tc 99m