In vitro antileukemic activity and chemical transformation of the 5'-chloro-5'-deoxy derivative of cyclocytidine.

Hydrochloride of 5'-chloro-5'-deoxy-cyclocytidine (Cl-cC) is an analogue of cyclocytine hydrochloride (cC), a prodrug of the compound with the strong antileukemic activity arabinosylcytosine (araC). This paper is devoted to the study of its cytotoxic activity in vitro and to the effect of acid and alkaline conditions and temperature on its stability. Cl-cC inhibits not only the growth of L1210 leukemia cells in vitro and the DNA synthesis (IC50 = 0.09 mumol/l) but, at the same time, it has a weak effect on RNA synthesis (IC50 > 250 mumol/l) and no effect on proteosynthesis. In alkaline conditions Cl-cC is transformed to 5'-chloro-araC and 2',5'-anhydro-araC but is more stable in acid solutions.

Diaziquone and 2,2'-anhydro-arabinosyl-5-fluorocytosine for the treatment of children with relapsed or refractory acute nonlymphoblastic leukemia.

The authors treated 30 patients ages 1 to 19 with relapsed or refractory acute non-lymphoblastic leukemia (ANLL) with the combination of diaziquone (AZQ) and 2,2'-anhydro-arabinosyl-5-fluorocytosine (AAFC) intravenously in two dose schedules. The first 12 patients were treated with 19 courses of AZQ 30 mg/m2 X 3 days and AAFC 600 mg/m2/dose every 12 hours X 10 doses. An additional patient was treated with three courses at 80% of the above doses. Hepatic toxicity was National Cancer Institute Grade III in eight of 22 and Grade IV in one of 22 courses. Infectious complications were severe in all patients, including responders. One patient achieved a complete remission and one a partial remission; the latter died with marrow aplasia after a second course. Altogether three patients developed profound aplasia and died before marrow recovery. The authors treated a second group of 17 patients with AZQ 22.5 mg/m2/day X 3 days and AAFC 450 mg/m2/dose every 12 hours X 10 doses. Three patients achieved a complete remission and one patient a partial remission for 3, 4, 9, and 9 months, respectively. The remainder had progressive disease or no response. All patients developed profound myelosuppression but no toxic deaths occurred. Hepatic toxicity was reduced. Therapy induced cytoreduction of bone marrow was determined by flow cytometry in ten patients; none of these patients responded during the interval studied. Although AZQ and AAFC are active in childhood ANLL with acceptable toxicity, the combination does not appear more active than AZQ used alone. Future studies should define the role of AZQ in combination with other agents.

1-(2,3-Anhydro-beta-D-lyxofuranosyl)cytosine derivatives as potential inhibitors of the human immunodeficiency virus.

We report here that 1-(2,3-anhydro-beta-D-lyxofuranosyl)cytosine has activity against the human immunodeficiency virus in vitro. A number of 2',3'-anhydro-beta-D-lyxofuranosyl nucleoside derivatives were prepared, but none had the activity of the title compound. New efficient procedures were developed for the synthesis of 3'-deoxy-3'-alkyl- and 3'-deoxy-beta-D-arabinosylpyrimidine derivatives.

Treatment of acute nonlymphocytic leukemia in adults: response to 2,2-anhydro-1-B-D-arabinofuranosyl-5-fluorocytosine and thioguanine on the L-12 protocol.

Fifty-one adult patients with acute nonlymphocytic leukemia (excluding acute promyelocytic leukemia) were treated on the L-12 protocol. The L-12 differed from the preceding L-6 in that 2,2-anhydro-1-B-D-arabinofuranosyl-5-fluorocytosine (AAFC), replaced arabinosylcytosine (ara-C) together with 6-thioguanine (TG) for remission induction. Achievement of remission was followed by an extended 14-week multi-drug consolidation program. With this more intense regimen, an overall complete remission rate of 49% and a median remission duration of 23.7 months were achieved; these results were not significantly better than the 57% complete remission rate and 8.6 months median remission duration obtained with the L-6 regimen. Four year disease-free survival was 22% on the L-12 compared with 16% on the L-6 protocol. No relationship between prognosis and FAB classification was found on either the L-6 or the L-12 protocol.

Inhibition by lymph node cells and promotion by fetal hepatocytes of murine tumours without or with chemotherapy.

The growth of a syngeneic Moloney lymphoma in CBA mice was inhibited by the injection of lymph node cells from normal CBA donors. This cytotherapeutic effect was also seen after chemotherapy with cyclophosphamide (CY) or dimethylmyleran (DMM). Two other murine tumours, the Meth A sarcoma in Balb/c mice and the L1210 leukemia in BDF1 mice, did not respond to treatment with normal syngeneic cells. In the L1210 system, tumour-promoting effects of fetal liver cells were demonstrated. The tumour inhibitory effects of normal lymph node cells against the Moloney lymphoma may be a virus-dependent phenomenon mediated through interferon and natural killer' cells. The experiments also showed the sensitivity of the Moloney lymphoma and the Meth A sarcoma to CY and DMM and the responsiveness of the L1210 leukemia to AAFC.

Anhydro-ara-5-fluorocytidine (AAFC) in gastrointestinal cancer. A phase II study.

Results of a phase II study of AAFC in 32 patients with advanced measurable gastrointestinal cancer are presented. Fourteen patients were treated with a weekly schedule, while 18 were treated with 5-day courses of the drug. There were 12 patients with pancreas cancer, eight with stomach cancer, seven with cancer of the esophagus, four with colorectal cancer, and one with cancer of the gallbladder. Response was observed in pancreas and stomach cancer. Two patients with pancreas cancer had partial remissions, three other patients (two pancreas and one stomach) had response of short duration, considered to be less than a partial remission. There appeared to be very little difference between the two different schedules of administration. AAFC shows limited activity in adenocarcinoma of pancreas and stomach; there does not appear to be a practical application for AAFC as a single agent.

The enzymatic hydrolysis of the phosphate ester bond in some thionucleotides.

We prepared the 5'- and 3'-O-phosphorothioate esters of the antitumor agent O2 : 2'-anhydro-1-beta-D-arabinosylcytosine. We also included in this study esters of 2'-thio-2'-deoxycytidine, namely, 2'-S-dCyd-2' : 3'-P, 2'-S-dCyd-2'-P, and 2'-S-dCyd-3'-P, along with natural nucleotides. These compounds were subjected to the action of Escherichia coli alkaline phosphatase, potato acid phosphatase, and bovine pancreatic ribonuclease A. The data were analyzed by Lineweaver-Burk plots to obtain Km and KI values. Only 2'-S-dCyd-2'-P was a substrate for alkaline phosphatase; the anhydro-araCyt phosphorothioates were good competitive inhibitors, while 2'-S-dCyd-3'-P did not associate with the enzyme. Acid phosphatase hydrolyzed all four monoesters investigated, including the S-phosphorothioate. The cyclic phosphorothioate, 2'-S-dCyd-2' : 3'-P was neither hydrolyzed by, nor associated with, ribonuclease A. ORD spectroscopy was also used in an attempt to relate the structural features of analogs to the peculiarity of their hydrolysis.

Phase I and II clinical study of anhydro-ara-5-fluorocytosine (AAFC) and ICRF-159 combination in adenocarcinoma of digestive origin.

The results of a phase I--II study of a combination chemotherapy with AAFC and ICRF-159 in advanced adenocarcinoma of digestive origin are presented. Myelosuppression was the dose-limiting toxicity with anemia, leukopenia, and thrombocytopenia. The maximum tolerated dose of AAFC in the combination program was 650 mg/m2 I.V. weekly. ICRF-159 was given in a 3-day course every 3 weeks and the dose was escalated from 125 mg/m2 to 500 mg/m2 daily. Bone marrow toxicity was noticied at the first escalation level and all dose levels were similarly toxic. The results of this combination chemotherapy were: two partial responses in 14 patients with gastric cancer; no responses in nine patients with colorectal cancer; no responses in three patients with pancreatic cancer; and no responses in two patients with biliary tree cancer. In conclusion, AAFC and ICRF-159 combination chemotherapy demonstrated a low level of activity in advanced carcinoma of digestive origin. The peculiar hematologic toxicity found at the low-level dose requires further documentation and could make this drug association suitable for a phase II study in leukemia and/or lymphoma.

Synergistic effects of the combination of cis-platinum diamminodichloride and 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine in transplanted mouse leukemias.

cis-Platinum diamminodichloride has been studied in combination with 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine on an every-4-day schedule in various lines of mouse leukemia. This combination is synergistic in leukemias L1210 and P388 and sublines made resistant to 5-fluorouracil or methotrexate. There is no cross-resistance between cis-platinum diamminodichloride and 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine, but the combination is no more effective against lines of leukemia made resistant to cis-platinum diamminodichloride or to 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine than either single active compound alone. Since these compounds have no cross-resistance, act by quite different mechanisms of action, and have different limiting toxicity, the combination is now being evaluated clinically.

Fluorinated Pyrimidine nucleosides. 1. Synthesis of a nitrogen analogue of the antitumor agent 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine hydrochloride.

The nitrogen-bridged compound 2,2'-anhydro-1-beta-D-arabinofuranosyl-2,4-diamino-5-fluoropyrimidinium chloride (2), an analogue of the antitumor agent anhydro-ara-FC (1), has been synthesized. 5-Fluorocytidine was converted into 1-beta-D-ribofuranosyl-2,4-diamino-5-fluoropyrimidinium chloride (4), but cyclization of 4 was not achieved due to a competing side reaction. The nitrogen bridge was therefore introduced by cyclization of 5-fluoroisocytidine (10) to give the 2,2'-imino-bridged compound 16. The latter was converted into 2 by the standard procedure of thiation, S-methylation, and treatment with ammonia. Compound 2, as well as a number of the synthetic intermediates, was tested for activity against S180 sarcoma in mice. None of the new compounds exhibited any antitumor activity.