LABORATORY STUDIES AND CLINICAL TRIALS OF CHEMICAL RADIO-SENSITIZERS 



X-ray therapy onl)-, about 6 months with X-ray therapy combined with 

 intramuscular compound and about 11 months with X-ray therapy com- 

 bined with intravenous compound. It is concluded that the results obtained 

 so far show that intravenous administration of Compound I has a small but 

 useful effect as a radio-sensitizer. 



Since August, 1953, clinical trials have been in progress of the combined 

 use of Compound I, oxygen administration before and during irradiation, 

 and X-ray therapy in the treatment of patients with advanced cancer. After 

 preliminary studies a randomized trial has been started. 



ADDENDUM 



ANIMAL EXPERIMENTS WITH THE WALKER CARCINOMA 256 



IN THE RAT 



(1) Distribution Studies 



With reference to the fluorescence method for study of the distribution of 

 Compound I in the rat with the Walker carcinoma 256, further measurements 

 of the fluorescence spectrum with Wood's light (wavelengths 3,650, 3,655 

 and 3,663 A) and of its behaviour with pH confirm that the compound 

 responsible for the fluorescence of the tissues is probably 2-methyl-l : 4- 

 naphthoquinone-2 : 3-oxide. Cut surfaces of tissues require about 6 hours 

 at room temperature in the presence of air for full development of this 

 fluorescent derivation of Compound I but the fluorescence develops within 

 15 to 30 minutes in the presence of alkali and hydrogen peroxide ; varying 

 concentrations between N/100 and 3N NaOH and 10 to 100 volume H2O2 

 have been used, the fluorescence developing most rapidly at the highest 

 concentrations. The fluorescence does not appear when the tissues are kept 

 in air at — 20°C and — 4°C, or are kept in nitrogen at room temperature 

 for 15 days, though the fluorescence starts to develop within 10 minutes 

 after the admission of air. 



In continuation of these investigations, the method of fluorescence micro- 

 scopy has been used to obtain information about the localisation of Com- 

 pound I or the compounds derived from it within the tumour cells. In 

 Figure 2 the appearances with fluorescence microscopy and the same area 

 of the tumour stained with toluidine blue are compared for a region in the 

 growing edge of the Walker carcinoma after treatment of the rat with large 

 intramuscular doses of Compound I. The essential features of the technique 

 are summarized in the legend to Figure 2. It must be mentioned that the 

 development of the fluorescence was accelerated by running N/100 NaOH 

 followed by 30 volume HPa and then further N/100 NaOH under the 

 coverslip. The upper left-hand part of the plates shows an area of actively 

 growing tumour ; below the margin of this is an area of mainly necrotic 

 and partly relatively inactive tumour. Comparison of the appearances with 

 fluorescence microscopy and toluidine blue staining of the actively growing 

 parts of the tumour show that in the proliferating cells not in mitosis the 

 fluorescent derivative of Compound I is concentrated mainly in the peri- 

 nuclear region of the cytoplasm of the tumour cells, with a paler peripheral 

 region and some fluorescent granules in the cytoplasm. 



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