PT  - JOURNAL ARTICLE
AU  - CHANG, CHIH-HSIEN
AU  - HSU, WEI-CHUAN
AU  - WANG, CHANG-YI
AU  - JAN, MEEI-LING
AU  - TSAI, TUNG-HU
AU  - LEE, TE-WEI
AU  - LYNN, SHU-GENE
AU  - YEH, CHUNG-HSIN
AU  - CHANG, TSUI-JUNG
TI  - Longitudinal MicroSPECT/CT Imaging and Pharmacokinetics of Synthetic Luteinizing Hormone-releasing Hormone (LHRH) Vaccine in Rats
DP  - 2007 Sep 01
TA  - Anticancer Research
PG  - 3251--3257
VI  - 27
IP  - 5A
4099  - http://ar.iiarjournals.org/content/27/5A/3251.short
4100  - http://ar.iiarjournals.org/content/27/5A/3251.full
SO  - Anticancer Res2007 Sep 01; 27
AB  - Background: Luteinizing hormone-releasing hormone (LHRH)-derived decapeptide-based vaccines have been used in studies of immunocastration and immunotherapy of prostate cancer, but no image data are available on the kinetics of vaccines post injection (p.i.). Therefore, an 131I radiolabeled LHRH-derived immunogen was developed to visualize and evaluate the retention of LHRH-derived vaccines in rats. Materials and Methods: The LHRH immunogens, which contained equal moles of 131I-p607E, p667 and p500, were formulated with an equal volume of an adjuvant, Montanide ISA50. MicroSPECT/CT imaging was performed to visualize the retention of the radiolabeled immunogen up to 30 days after intramuscular inoculation of 25 μg immunogens. The pharmacokinetics, distribution and excretion were also evaluated. Results: The radiochemical purity of 131I-p607E was 97.85±2.12%. The longitudinal microSPECT/CT imaging revealed that most 131I-p607E was retained at the injected muscle site until 30 days p.i.. Biodistribution showed that 34.56±4.27% of radioactivity remained at the injected muscle site at 28 days p.i.. The cumulative radioactivity excreted via urine was 30.02±3.82% up to day 28 p.i.. The elimination half-life (t1/2), Tmax, and Cmax were 158.67 h, 24 h, and 0.026 percentage of injected dose per gram (%ID/g), respectively. Conclusion: The LHRH immunogen, 131I-p607E, was mainly retained at the intramuscular injection site during the whole study period. The microSPECT/CT imaging modality can be used to monitor the location and distribution of the LHRH immunogen, 131I-p607E, in a rat model. Copyright© 2007 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved