[Studies on hyperthermia by the use of a thermosensitizing drug]

Hyperthermic treatment using ACNU combined with a thermosensitizing drug, methylglyoxal-bis-guanylhydrazone (MGBG), was studied in human gastric cancer xenotransplanted into nude mice. In order to increase the intra-cellular MGBG content, intraperitoneal injection of alpha-difluoromethylornithine(DFMO) 1000 mg/kg was performed twice with an interval of 6 hours and 50 mg/kg of MGBG was given at the time of the second administration of DFMO. After 6 hours of MGBG administration, ACNU 20 mg/kg was given intraperitoneally and, subsequently a 23-minute hyperthermia was carried out in a water bath at 43.5 degrees C. After 48 hours a second hyperthermia was performed by the same method. Tumor weight was estimated using Battelle's Columbus Institute protocol and the inoculated tumors, which were extirpated 60 minutes after 3H-thymidine injection at a prescribed interval after cessation of hyperthermia, were assayed biochemically for the determination of DNA biosynthesis. In mice given ACNU, DFMO, MGBG plus heat, considerably superior results were obtained. Although the DFMO plus MGBG group was inferior in antitumor activity to the ACNU only or heat only group, the DFMO, MGBG plus heat group showed much the same antitumor effects, compared to the ACNU plus heat group. These data suggest that the thermosensitizing efficacy of MGBG may be applicable for clinical use.