New high O2 carrying perfluorochemical emulsions and/or carbogen: reactions of a human tumor xenograft to irradiation.

The effects of two new perfluorochemical emulsions based on F-66E and PFOB which carry, in combination with carbogen, more oxygen than Fluosol-DA 20% were investigated on a human tumor xenograft (HRT18). Tumor bearing mice were pretreated with 15 ml/kg of F-66E emulsion (50 w/v%) or PFOB (100 w/v%) emulsion in the presence of carbogen for 1 hr prior to and during irradiation. F-66E emulsion was non toxic in vitro. In vivo, the dose modifying factor was 1.8 for mice pretreated with carbogen and F-66E emulsion whereas it was 1.6 for carbogen-breathing mice. Results with PFOB emulsion were similar to those obtained with F-66E emulsion. The effect of F-66E emulsion was studied using a fractionated radiation treatment: 12 Gy were delivered in 6 fractions of 2 Gy with an interval of 8 hrs between fractions. A single dose of F-66E emulsion was injected before the first irradiation. Surviving fractions were 0.35 for air-breathing mice, 0.091 for carbogen-breathing mice and 0.099 for carbogen-breathing mice pretreated with F-66E emulsion. These results showed that carbogen alone or carbogen plus F-66E or PFOB emulsion were very efficient even with low doses of radiation.