Interaction of hyperthermia and the hypoxic cell sensitizer Ro-07-0582 on the EMT6 mouse tumour

The combination of hyperthermia and the hypoxic cell radiosensitizer Ro-07-0582 has been investigated on the EMT6 tumour implanted into the legs of BALB/c mice. Treatments at a drug dose of 1 mg/g over a range of waterbath temperatures from 37 to 45 degrees C are described. The surviving clonogenic fraction following treatment was assayed in vitro. Measurements of intra-tumour temperature have been made, and shown to be better correlated with the cytocidal effect on the tumour than the waterbath temperature. No significant effect of Ro-07-0582 was observed at 37 degrees C. However, marked cytotoxicity due to the drug was seen at intra-tumour temperatures above 42-5 degrees C for 1 h. These were in addition to the cytocidal effect of the hyperthermia. The results are discussed in relation to the distribution of temperatures and hypoxic cell populations throughout the tumour.