Evaluation of (99m)Tc-labeled photosan-3, a hematoporphyrin derivative, as a potential radiopharmaceutical for tumor scintigraphy.
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 tissue distribution in a murine tumor model. The (99m)Tc-Photosan-3, which was prepared by using (99m)Tc-pertechnetate in place of reduced (99m)Tc, demonstrated better labeling efficiency (>90%) and reproducibility. The procedure also minimized radiation exposure to the radiochemist because 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 similar to the parent compound. In addition to its 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.
Department of Radiopharmaceuticals, Institute of Nuclear Medicine and Allied Sciences, Lucknow Marg, Delhi, India.
A K
AK
Babbar
A K
AK
Singh
H C
HC
Goel
U P
UP
Chauhan
R K
RK
Sharma
D000818:Animals; D001103:Arboviruses; D004355:Drug Stability; D006415:Hematoporphyrins; D007553:Isotope Labeling; D009374:Neoplasms, Experimental / Q000000981:diagnostic imaging*; D017319:Photosensitizing Agents / Q000737:chemistry / Q000493:pharmacokinetics; D011485:Protein Binding; D011817:Rabbits; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013667:Technetium; D014018:Tissue Distribution
D006415:Hematoporphyrins; D017319:Photosensitizing Agents; D019275:Radiopharmaceuticals; C071875:photosan III; D013667:Technetium