[Enhancement of anti-cancer effect by potential lethal damage repair(PLDR)-inhibitors]

Nucleoside analogues (3'-dG, Ara-A) have recently been found to be an effective chemical substance for inhibiting the recovery of potential lethal damage caused by radiation and anti-cancer drugs. By combination of radiation and inhibitors, both Ara-A and 3'-dG produced a higher sensitivity effect closer to the center of "Spheroid". In the experimental tumor S-180, combination of adriamycin , cyclophosphamide and Ara-A produced an eminent sensitivity effect amounting to the enhancement ratio of 1.24 and 1.36. By combination of 5-FU and 3'-dG, an enhancement ratio of 1.39 was obtained. These findings indicate the possibility that these inhibitors may be used as a chemosensitizer and also suggest that they would be useful for chemotherapy in the future.