BLADDER INSTILLATION OF ADRIAMYCIN IN THE TREATMENT OF BLADDER TUMORS

REPORT 2: EXPERIMENTAL STUDY

Abstract

In an experimental study undertaken to elucidate the mechanism whereby Adriamycin (ADM), an anticancer antibiotic, instilled into the bladder, produces its side-effects, normal adult dogs with bilateral ureterostomy were treated with intravesically instilled ADM and subsequently were investigated for the time course of ADM concentration in blood, urine and tissues of various organs as well as histopathological changes in the bladder mucosa. In a separate experiment conducted as a basic approach to the drug effect on bladder tumors, human bladder tumor tissues were exposed to ³H-thymidine (³H-TdR) and ³H-ADM and then the incorporation of these tritiated compounds into tumor tissues was determined by autoradiography.
1) Concentrations of ADM in blood, urine and tissues
ADM was instilled into the bladder of the animals at the following 4 different concentrations: Group 1 (Nos. 1-3), 10mg ADM/10ml physiological saline (1000mcg/ml); Group 2 (Nos. 4-6), 20mg ADM/ 10ml physiological saline (2000mcg/ml); Group 3 (No. 7), 100mg ADM/10ml physiological saline (10000mcg/ml); Group 4, (No. 8) 20mg ADM/10ml physiological saline (2000mcg/ml) preceded by a 100mg/kg intravenous dose of cyclophosphamide given 48 hours before surgical treatment (ureterostomy). In Groups 1 and 2 the experiment was performed with a different retained time and a different time of animal killing. Tissue levels of ADM were measured by determining the intensity of fluorescence. Blood levels of ADM were relatively low, but Case No. 7 showed considerably higher values than the cases in the other groups and Case No. 8 also exhibited higher values as compared with other cases receiving the drug at the same concentration. Urinary levels of the drug were somewhat higher than blood levels. Concerning tissue levels of ADM in the bladder, the level in mucosa is higher than that in muscular layer except No. 1. Levels of ADM in tissues other than bladder tissues became higher as the duration of exposure to the drug became longer. Moreover, the data suggested that the dynamics of blood levels yielded after systemic uptake of the drug from the bladder is similar to that observed following the intravenous administration of the drug.
2) Histological changes (bladder mucosa)
Case with a 6-hr. exposure to 2000mcg/ml ADM demonstrated shedding of epithelial elements of the bladder and marked edema as well as infiltration by neutrophils of the submucosa, changes comparable to those observed with 10-hr. exposure to the drug. These findings suggest the possibility that even in the intact bladder prolonged exposure to a concentration of 2000mcg/ml of ADM might induce noticeable histological changes in the bladder mucosa. Histological changes in the bladder mucosa were more conspicuous in Case No. 8 than in other cases exposed to the same concentration of ADM and still more marked in Case No. 7. From these facts the maximum safe concentration of ADM for bladder instillation is estimated to be 2000mcg/ml.
3) Autoradiography
The uptake of ³H-ADM by the bladder mucosa was demonstrated to be complete in all cases with the labeling index being invariably 100% irrespective of the presence or absence of bladder tumor and also independent of its grade.
A study of the uptake of the tritiated compounds by bladder tumor following its 30-min. incubation in a medium added with cold ADM at the same concentration as ³H-ADM 1μCi/ml revealed that whereas the tissue content of ³H-TdR was low as compared with control level, the incorporation of ³H-ADM was totally unaffected, the labeling index thus being 100%. These findings suggest that the cellular uptake of ADM might be independent of the condition of cells.