Microradiopharmaceutical for Metastatic Melanoma.

PURPOSE: The purpose of this article was to develop, characterize and test (in vivo) dacarbazine microparticles that may be labeled with 99mTc and Ra-223 for both use: diagnostic and therapy of metastatic melanoma.

METHODS: We developed by double emulsion solvent evaporation methodology the microparticle. The characterization has been done using, Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM). The labeling with 99mTc and Ra-223 has been done by the direct labeling process. Also the formulation has been tested pre-clinically using Balb/c mice inducted with melanoma, performing the the biodistribution and planar imaging. Cytotoxicity evaluation was also done in M3 V cell line. In order to understand the safety aspects of the microparticles, microbiological study (endotoxin and sterility) has been done. Finally, planar imaging was performed to evaluate the diagnosing aspect.

RESULTS: The results showed that a 559 nm microparticles was obtained with a spherical shape. The labeling process with 99mTc reached over 90% of efficacy. On the other hand, the labeling process with Ra-223 showed a 70% efficacy. The results in inducted animals demonstrated that the microparticles were able to reach the tumor with a high rate (20%). Also demonstrated a low recognition by the Mononuclear Phagocytic System. The cytotoxicity and the microbiological control, corroborates the safety aspect of these microparticles.

CONCLUSION: The planar image and the possible labeling with Ra-223, corroborates the use as a theragnostic agent for imaging and therapy of Metastatic Melanoma.