pyrazofurin and Lung-Neoplasms

Topics: Adenocarcinoma; Adult; Aged; Amides; Antibiotics, Antineoplastic; Carcinoma, Squamous Cell; Clinical Trials as Topic; Drug Evaluation; Humans; Lung Neoplasms; Middle Aged; Neoplasm Metastasis; Pyrazoles; Ribonucleosides; Ribose

Results following liver transplantation for hepatocellular carcinoma have been dismal, attributed largely to recurrent disease locally or at distance sites. Undetected micrometastases or tumor that embolizes at the time of liver transplant from manipulation of the liver may account for these recurrences. A model and treatment protocol were developed to address this clinical problem. The protocol is modeled on the concept of bone marrow transplantation for leukemia. Hepatotoxins that are lethal to both normal hepatocytes and hepatoma cells are administered followed by liver transplantation to "rescue" the failing liver. The feasibility of this protocol was examined in a rat model. Male Buffalo rats were injected with 1 million Morris hepatoma MH-7777 cells intravenously at Day 0 as a model for micrometastatic disease. Three treatment groups were established. Group 1 received no treatment. Group 2 received 5% dextrose in water (D5W) followed by a syngeneic orthotopic liver transplant (OLTX). Group 3 received the hepatotoxin pyrazofuin (10 mg/kg) followed by OLTX. Animals were followed to Day 35, at which time they were sacrificed and examined for evidence of pulmonary metastases and quantitation of nodules with India ink insufflation. There was a significant decrease in the number with pulmonary nodules as well as the number of animals with pulmonary metastatic disease in the pyrazofurin-treated group compared with groups 1 and 2 (4.8 +/- 4.0 nodules/animal vs 45.2 +/- 11.2 nodules/animal--no treatment and 60.8 +/- 21.4 nodules animal--D5W/OLTX group) These data indicate that this model is reliable for examining metastatic hepatoma and that pyrazofurin is effective in preventing hematogenous micrometastases of hepatoma cells. Other hepatotoxins and the effect of allogeneic transplantation and immunosuppression could be examined in this model.

Topics: Amides; Animals; Antibiotics, Antineoplastic; Disease Models, Animal; Injections, Intravenous; Liver; Liver Neoplasms, Experimental; Liver Transplantation; Lung Neoplasms; Male; Neoplasm Transplantation; Pyrazoles; Rats; Rats, Inbred BUF; Ribonucleosides; Ribose; Tumor Cells, Cultured

A number of nucleoside and nucleotide derivatives of 4-hydroxy-3-beta-D-ribofuranosylpyrazole-5-carboxamide (pyrazofurin, 1) were prepared and tested for their antiviral and cytostatic activity in cell culture. Treatment of 1 with benzyl bromide gave 4-O-benzylpyrazofurin (4). Methylation of 4 with CH2N2 and subsequent removal of the benzyl group by catalytic hydrogenation provided 1-methylpyrazofurin (8). Direct methylation of 1 with CH3I furnished 4-O-methylpyrazofurin (6). Dehydration of the pentaacetylpyrazofurin (9) with phosgene furnished 4-acetoxy-3-(2,3,5-tri-O-acetyl-beta-D-ribofuranosyl)-1-acetylpyrazol e-5-carbonitrile (10). A similar dehydration of the precursor tetraacetyl derivative of 4 gave the corresponding carbonitrile, which on deprotection and subsequent treatment with hydroxylamine furnished 4- (benzyloxy)-3-beta-D-ribofuranosylpyrazole-5-carboxamidoxime (13). Treatment of the tetraacetyl derivative of 4 with Lawesson's reagent and subsequent deacetylation furnished a mixture of 4- (benzyloxy)-3-beta-D-ribofuranosylpyrazole-5-thiocarboxamide (15) and the corresponding nitrile derivative (16). Phosphorylation of unprotected 4 with POCl3 and subsequent debenzylation of the intermediate 17 gave pyrazofurin 5'-phosphate (18), which provided the first chemical synthesis of 18. Similar phosphorylation of 4 with POCl3 and quenching the reaction mixture with either EtOH or MeOH, followed by debenzylation, furnished the 5'-O-(ethyl phosphate) (19b) and 5'-O-(dimethyl phosphate) (20b) derivatives of pyrazofurin. DCC-mediated cyclization of 17, followed by debenzylation, gave pyrazofurin 3',5'-(cyclic)phosphate (21b). The NAD analogue 23b was also prepared by the treatment of 17 with an activated form of AMP in the presence of AgNO3. The structural assignment of 7,8, and 20a were made by single-crystal X-ray analysis, and along with pyrazofurin, their intramolecular hydrogen bond characteristics have been studied. All of these compounds were tested in Vero cell cultures against a spectrum of viruses. Compounds 18 and 23b were active at concentrations very similar to pyrazofurin but are less toxic to the cells than pyrazofurin. Compounds 19b, 20b, and the 3',5'-(cyclic)phosphate 21b are less active than 1. Compounds 18, 19b, 20b, and 23b also exhibited significant inhibitory effects on the growth of L1210 and P388 leukemias and Lewis lung carcinoma cells in vitro, whereas B16 melanoma cells were less sensitive to growth inhibition by these compou

Topics: Amides; Animals; Antineoplastic Agents; Antiviral Agents; Hydrogen Bonding; Leukemia, Experimental; Lung Neoplasms; Melanoma; Mice; Nucleosides; Nucleotides; Pyrazoles; Ribonucleosides; Ribose; Structure-Activity Relationship; X-Ray Diffraction

The combination of pyrazofurin (PF) and 5-azacytidine (5-aza-CR) was evaluated in 12 patients with neoplastic diseases who had failed conventional therapies. They included 6 patients with acute myelocytic leukemia (AML) and 6 with various carcinomas. PF was given by i.v. bolus at doses ranging from 25 to 200 mg/m2 followed by 5-aza-CR given by continuous 24-hour infusion at doses ranging from 30 to 120 mg/m2/24 h during 40-ic diseases who had failed conventional therapies. They included 6 patients with acute myelocytic leukemia (AML) and 6 with various carcinomas. PF was given by i.v. bolus at doses ranging from 25 to 200 mg/m2 followed by 5-aza-CR given by continuous 24-hour infusion at doses ranging from 30 to 120 mg/m2/24 h during 40-ic diseases who had failed conventional therapies. They included 6 patients with acute myelocytic leukemia (AML) and 6 with various carcinomas. PF was given by i.v. bolus at doses ranging from 25 to 200 mg/m2 followed by 5-aza-CR given by continuous 24-hour infusion at doses ranging from 30 to 120 mg/m2/24 h during 40--120 h. Dose-limiting toxicity was mucocutaneous, which appeared in 11/17 courses. Skin rash was similar to that produced by PF alone, but was present after much lower doses of PF when followed by 5-aza-CR. Moderate and reversible thrombocytopenia and leukopenia occurred in 3/6 patients with carcinoma. No objective response was seen in patients with carcinoma, and no marrow remission occurred in patients with AML. 24-Hour urinary excretion of orotidine and oroticacid were measured during 11 courses in 8 patients, and were not much different than those obtained previously with PF alone. The occurrence of mucocutaneous toxicity precluded the use of higher doses of PF and 5-aza-CR, which might have been therapeutically more active.

Topics: Adenocarcinoma; Adult; Aged; Amides; Azacitidine; Carcinoma; Carcinoma, Small Cell; Drug Therapy, Combination; Female; Humans; Leukemia, Myeloid; Lung Neoplasms; Male; Middle Aged; Pyrazoles; Ribonucleosides; Ribose

Variants of the Lewis lung carcinoma were selected for resistance to N-(phosphonacetyl)-L-aspartic acid (PALA) by treatment of tumor-bearing mice with repetitive subcurative doses of PALA. The specific activity of the target enzyme, L-aspartic acid transcarbamylase (ATCase), was measured in the four variants developed. Three had markedly elevated ATCase activities; however, the fourth line, LL/PALA-C, had an ATCase activity identical to that of the parent, PALA-sensitive line (LL/O). One high-ATCase variant, LL/PALA-J, and LL/PALA-C were compared with LL/O in subsequent biochemical studies on the mechanism of resistance to PALA. Enzyme activities in the salvage pathways which phosphorylate pyrimidine nucleosides and deoxynucleosides were found to be similar in all three lines. ATCase in these lines exhibits closely comparable kinetics with its natural substrates as well as with PALA. The time courses of restitution of ATCase after a single therapeutic dose of PALA show that both resistant variants recover full activity more rapidly than the parent. Additionally, inhibition of ATCase 24 hr following graded doses of PALA is lower in the resistant lines. The uptake of [14C]PALA in vitro into cell lines derived from the three Lewis lung carcinomas apparently occurs by passive diffusion and at comparable rates in both sensitive and resistant cells. Analysis of the nucleotide content of tumors reveals comparable spectrums of purine and pyrimidine nucleotide levels in the LL/O and LL/PALA-C lines, whereas the LL/PALA-J line has augmented nucleotide pools. In all three lines, 24 hr after treatment with PALA (400 mg/kg), uridine and cytidine nucleotide levels were substantially diminished (70 to 80%) while adenosine 5'-triphosphate and guanosine 5'-triphosphate levels were elevated (50 to 100%). Estimations of precursor flux through the de novo pyrimidine pathway by measuring orotate and orotidine levels in tumors of mice treated with pyrazofurin (an inhibitor of orotidine-5'-monophosphate decarboxylase) and either 0.9% NaCl solution or PALA shows that PALA treatment eliminates orotate and orotidine accumulation in LL/O but reduces it by only 75 and 50% in LL/PALA-C and LL/PALA-J, respectively. Similarly, PALA treatment (20 microM) of tumor lines in culture provokes a dramatic decrease in the incorporation of NaH14CO3 into pyrimidine intermediates and nucleotides in the LL/O cell line only. Determinations of specific activities of the other enzymes in this pathway

Topics: Amides; Animals; Aspartate Carbamoyltransferase; Aspartic Acid; Carcinoma; Cell Line; Dose-Response Relationship, Drug; Drug Resistance; Lung Neoplasms; Mice; Neoplasms, Experimental; Orotic Acid; Phosphonoacetic Acid; Pyrazoles; Pyrimidines; Ribonucleosides; Ribose