Joseph L. Skibba

Intrahepatic arterial infusion with 5-fluorouracil

Since 1964, 200 patients were treated with intra‐arterial 5‐FU infusion. Of them, 127 failed with intravenously injected 5‐FU, and 27 were unsuitable for such treatment as their involvement was so far advanced as to have jaundice due to extensive parenchymal involvement. In all but 12 patients, the catheter was placed percutaneously through the brachial artery. The criteria for improvement included at least a 6‐cm decrease in distance of the liver edge from the xiphoid or costal margin, a 50% decrease in the abnormal enzyme studies, a return of elevated bilirubin levels to normal so that jaundice disappeared, and all these responses continued for at least 2 months. Inpatients were treated with 5‐FU, 25 mg/kg/day × 4, then 15 mg/kg/day for 7 or 8 days. If no toxicity appeared, the 5‐FU was then increased to 20 mg/kg/day until the total infusion period was 21 days, and the catheter was removed. Outpatients received 500 mg daily in 140 ml 5% dextrose and 2,500 units heparin daily for 90 days, and then the catheter was removed. Following the termination of the infusion, the patient was given weekly intravenous doses of 5‐FU at 15 mg/kg. After several months, with reactivation of the disease, the intra‐arterial infusion was repeated. Minimal toxicity occurred, and there was one death from the procedure. Morbidity in the forms of infection and hemorrhage did occur, but, in the last 100 patients, there were only 2 minor infections. Of 113 study patients, 69 (61%) met our criteria of improvement and had a median survival of 8.7 months. Forty‐four (39%) failed, and their median survival was 2.5 months. This demonstrates a significantly increased survival in the responders.

Methylation of nucleic acids and urinary excretion of 14C-labeled 7-methylguanine by rats and man after administration of 4(5)-(3,3-Dimethyl-1-triazeno)-imidazole 5(4)-carboxomide

4(5)-(3,3-Dimethyl-1-triazeno)imidazole-5(4)-carboxamide (DIC) demonstrated alkylating activity when 14 C-methyl DIC was administered to 2 patients po and to 2 rats ip. Fractionation of urinary purines from the first 6-hr urine samples obtained from these species showed a peak of radioactivity in the 7-methylguanine fraction, with only a trace of radioactivity in the adenine and guanine fractions. The 7-methylguanine was recrystallized to constant specific activity. Three rats were administered 14 C-methyl DIC ip. After 5 hr the animals were sacrificed and the nucleic acids of the livers, kidneys, lungs, and brains were extracted, hydrolyzed, and subjected to ion-exchange chromatography. Radioactivity in the column effluent from the DNA and RNA of the livers was localized in the 7-methylguanine fraction with only a trace of radioactivity in guanine and adenine fractions. Hydrolyzates of nucleic acids obtained from the kidneys, lungs, and brains showed a significant radioactive 7-methylguanine peak, but the proportion of radioactivity in guanine and adenine was higher than that found in the liver nucleic acids. 14 C-Methyl DIC was incubated with rat liver microsomes in vitro. Radioactive 7-methylguanine was isolated by ion-exchange chromatography of the ribosomal RNA hydrolyzate and from the supernatant fraction of the ribosomal reaction carried out in the presence of guanosine. Enzymatic conversion of DIC to 4(5)-(3-monomethyl-1-triazeno)imidazole-5(4)-carboxamide (MIC) which spontaneously generated a methylating intermediate, diazomethane, was proposed as a possible mechanism for the alkylating activity of DIC.

Metabolism of 4(5)-(3,3-dimethyl-1-triazeno)imidazole-5(4)-carboxamide to 4(5)-aminoimidazole-5(4)-carboxamide in man

Abstract Administration of4(5)-(3,3-dimethyl-1-triazeno)imidazole-5(4)-carboxamide (DIC), a structural analogue of 4(5)-aminoimidazole-5(4)-carboxamide (AIC), i.V. or P.O., to patients with cancer was followed by increased urinary AIC excretion. After a single i.v. administration of 4.5 mg/kg of DIC, AIC excretion in the 24-hr period after DIC administration was 20 per cent of the dose of DIC given. When the same dose was given p.o., about 16.5 per cent of the dose of DIC was excreted as AIC within 24 hr. One patient given DIC p.o. at a dose of 1.5 mg/kg every 6 hr for four consecutive doses excreted about 13.6 per cent of each dose as AIC in each 6-hr period. Two patients were given DIC-2- 14 C p.o. Ion-exchange chromatography of plasma samples resulted in the detection of a peak of radioactivity in the column eluate fraction containing AIC. After ion-exchange chromatography of urine samples, 20.9 and 8.7 per cent, respectively, of the radioactivity appeared in the AIC fractions. 14 C-AIC was isolated from urine and characterized by paper-chromatographic behavior, ultraviolet fluorescence and color reaction after diazotization and coupling identical to that of authentic AIC, and was recrystallized to constant specific activity. The specific activity of the urinary 14 C-AIC from one patent was 78 per cent of that of the DIC-2- 14 C given. These data suggest that in man most of the increased urinary AIC excretion observed after DIC administration is the direct result of metabolism of DIC. The mechanism(s) of action of DIC as an antitumor agent in man is unknown.

Induction of thymic lymphosarcoma and mammary adenocarcinomas in rats by oral administration of the antitumor agent4(5)‐(3,3‐dimethyl‐l‐triazeno)imidazole‐5(4)‐carboxamide

4(5)‐(3,3‐dimethyl‐l‐triazeno)imidazole‐5(4)‐carboxamide (DICNSC 45388)and anticancer drug with activity against rodent and human tumorswas tested for carcinogenic activity by feeding a mean cumulative dose of 740 mg/rat/14 weeks to 24 female Sprague‐Dawley weanling rats. The first mammary tumor was palpated 10 weeks after the start of feeding DICand by 18 weekswhen the experiment was terminatedall 24 rats had developed an average of 5 mammary adenocarcinomas. Lymphosarcoma was present in the thymus of all rats and in the spleen (20/24)lymph nodes (18/24)and bone marrow (12/24). Ependymomas of the brain were present in 9 rats and pulmonary alveolar carcinomas in 4 rats. No tumors were found in the negative control group of 24 rats. DIC appears to be a potent chemical carcinogen that may exert its carcinogenic activity by the alkylation of biopolymers.

A sensitive method for the determination of plasma and urinary 4(5)-amino-5(4)-imidazole carboxamide

Abstract A new, simple, rapid and highly specific method for the assay of urinary 4(5)-amino-5(4)-imidazole carboxamide (AIC) was described. The method is based on the removal of interfering substances in the urine by anion- and cation-exchange resins. The AIC eluted from the cation-exchange resin is measured by diazotization and coupling. AIC was the only diazotizable amine present in the fraction analyzed. Results found with this method were compared to those previously reported in the literature.

Effects of 4(5)-(3,3-dimethyl-1-triazeno)-imidazole-5(4)-carboxamide (NSC 45388) in proliferating rat tissues

Abstract Some effects of 4(5)-(3,3-dimethyl-1-triazeno)imidazole-5(4)-carboxamide (DIC) on normal proliferating tissues in rats were described. DIC caused marked but transient inhibition of labeled thymidine incorporation into DNA and presumably DNA synthesis of thymus, regenerating liver, spleen and small intestine. The inhibition was reversible and its duration dose dependent. When incorporation of precursors into DNA was markedly inhibited, no consistent concomitant effect on incorporation of precursors into RNA or protein was observed. Karyorrhectic cells appeared in the intestinal crypts as well as signs of necrosis in the thymus after administration of 125 mg/kg of DIC, but no significant pathologic changes were found in the spleen or regenerating liver. The relationship between selective inhibition of DNA synthesis and cytotoxic effect was observed.