[Platinum complexes as radiosensitizers in radiotherapy]

The authors study the radiosensitizing effect of cisplatinum, cis-dichloroethylenediamine platinum (II), and cis-dichlorobis-cyclohexylamine platinum (II) by the of TC-SV40 cells radiated under aerobic and hypoxic conditions. Cis-platinum shows the highest radiosensitizing activity but is very toxic. Perhaps cis-dischloro-bis-cyclohexylamine platinum (II) could be assayed as a less toxic radiosensitizing agent. On the other hand, DNA synthesis is studied in mouse spleen and TC-SV40 cells labeled with tritiated thymidine. Cis-platinum inhibitory activity is related to the preincubation time, cis-dichloroethylenediamine platinum(II) does not inhibit the semiconservative synthesis and stimulates the repair synthesis of DNA, and cis-dichloro-bis-cyclohexylamine platinum (II) produces a 60 per 100 inhibition of the semiconservative synthesis and a smaller inhibition of the repair synthesis.