Intratumoral injection with [(188)Re]rhenium sulfide suspension for treatment of transplanted human liver carcinoma in nude mice.

Hepatocellular carcinoma (HCC) is one of the most common malignancies in China. Direct intratumoral injection of nonremovable radioactive material has been widely studied because it could deliver high doses of radiation to target sites and minimize radiation leakage to non-target organs or tissues. Thirty nude mice bearing SMMC 7721 human liver carcinoma were used for the biodistribution study after intratumoral injection of [(188)Re]rhenium sulfide suspension or sodium [(188)Re]perrhenate solution. Another 30 tumor-bearing mice were divided into six groups, four groups of which were treated with a 0.1 ml [(188)Re]rhenium sulfide suspension at doses of 3.7, 7.4, 18.5, 29.6 MBq by a single intratumoral injection. For control studies, to study the tumor inhibiting ratio, the remaining two groups were injected with nonradioactive rhenium sulfide suspension and Hanks' balanced salt solution, respectively. The injections were repeated 6 days later. The retention percentages of radioactivity (%ID) in tumors injected with [(188)Re]rhenium sulfide suspension were 90.96+/-6.63%, 86.09+/-22.58% and 87.62+/-13.97% at 1, 24 and 48 h, respectively. Tumor inhibition ratios are as high as 89% when the outer space of tumor (0.5-0.6 cm from center) received about 507.6 Gy doses. Intratumoral injection of [(188)Re]rhenium sulfide suspension results in high tumor retention indicating this approach has strong potential for the treatment of hepatic carcinoma.

[188Re]Rhenium sulfide suspension: a potential radiopharmaceutical for tumor treatment following intra-tumor injection.

Intralesional therapy has been shown to be an effective treatment for tumors. In this study, the suitability of [188Re]rhenium sulfide suspension for tumor treatment following intra-tumor injection was evaluated. The [188Re]rhenium sulfide suspension was radiolabeled with 188Re with a radiochemical yield of more than 96%. In vitro stability studies revealed that more than 99% of the 188Re remained in sulfide form over a 3-day period. After ultrasonication for 5 or 10 min, the main particle size was 1-5 microm. Two [188Re]rhenium sulfide suspensions ultrasonicated for 5 and 10 min, respectively, were injected into separate group of tumor-bearing mice that were killed after specified times to compare the retention of 188Re in tumors and the leakage to different organs by periods and organs removed to gamma counting. The mean retention percentages of 188Re in tumors injected with suspension ultrasonicated for 5 (or 10) min were as follows: 1 h, 90.5 +/- 7.7% (83.1 +/- 13.7%); 24 h, 92.2 +/- 8.6% (83.9 +/- 9.8%); 48 h, 88.3 +/- 10.9% (80.2 +/- 3.8%); and 72 h, 91.5 +/- 7.6% (78.8 +/- 3.0%). Tumor-inhibiting ratio was 96.5%. These results demonstrated that [188Re]rhenium sulfide suspension is an effective radiopharmaceutical for tumor treatment by intralesional therapy.