Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chlorozotocin, 2-(3-(2-chloroethyl)-3-nitrosoureido)-D-glucopyranose, is a newly synthesized, water-soluble nitrosourea antitumor agent that is active against L1210 leukemia in mice. A 701% and a 401% increase in life-span were attained with a dose that was lethal to 10% of the animals (15 to 20 mg/kg, i.p.) in mice treated on Day 2 or Day 6 of L1210 tumor growth, respectivley. Sixity % of Day 2-treated mice and 30% of Day 6-treated mice survived for 90 days. At the maximally effective dose against L1210, chlorozotocin produced no significant depression in normal bone marrow DNA synthesis nor in peripheral neutrophil count, in contrast to a sustained greater than 90% inhibition in L1210 ascites cell DNA synthesis. If the antitumor activity and reduced bone marrow toxicity of chlorozotocin are confirmed in man the use of this compound would facilitate treatment of patients with neoplastic disease who have preexisting abnormal bone marrow function or would allow for the more effective use of a nitrosourea agent in combination with anticancer agents possessing more potent myelosuppressive properties.
 ...
PMID:Chlorozotocin, 2-(3-(2-chloroethyl)-3-nitrosoureido)-D-glucopyranose, an antitumor agent with modified bone marrow toxicity. 12 70

Chlorozotocin is a chloroethyl nitrosourea with a glucose carrier that has curative activity for the murine L1210 leukemia, but is nonmyelosuppressive in mice. To determine the mechanism for this unique property of reduced bone marrow toxicity, comparative studies were conducted with chlorozotocin and CCNU, a myelotoxic chloroethyl nitrosourea. Suspensions of L1210 leukemia and murine bone marrow cells were incubated for 2 h with 0.1 mM [(14)C]-chloroethyl chlorozotocin or CCNU. Chlorozotocin demonstrated a fourfold increased covalent binding of the chloroethyl group to L1210 nuclei when compared to equimolar CCNU. Chlorozotocin alkylation of L1210 cells resulted in the binding of 57 pmol of [(14)C]ethyl group/mg of DNA, which represented a 2.3-fold increased alkylation when compared to CCNU. In marked contrast, the binding of the chloroethyl group to bone marrow nuclei was equivalent for both drugs. In addition, chlorozotocin alkylation of murine bone marrow DNA, 45 pmol of [(14)C]ethyl group/mg of DNA, was equivalent to that of CCNU. The ratio of L1210:bone marrow DNA alkylation was 1.3 for chlorozotocin compared to 0.6 for CCNU. The intracellular carbamoylation of L1210 and bone marrow protein by CCNU was 400- to 600-fold greater than that produced by chlorozotocin. After a 2-h exposure to 0.1, 0.05, or 0.01 mM drug, both chlorozotocin and CCNU produced a reduction in the cloning efficiency of L1210 cells that was dose dependent. However, chlorozotocin was significantly more cytotoxic than CCNU at all three molar concentrations (P < 0.01). Chlorozotocin, 0.1 mM, reduced L1210 DNA synthesis to 1% of control by 48 h, in contrast to 16% with equimolar CCNU (P < 0.01). In mice bearing 10(5) L1210 cells, chlorozotocin produced its optimal antitumor activity (332% increased life span [ILS]) at doses of 48-64 mumol/kg, with >50% indefinite survivors. In contrast, CCNU at the same molar doses resulted in only a 191% ILS; a CCNU dose of 128 mumol/kg was required for comparable optimal L1210 antitumor activity, 413% ILS. On a molar basis, the dose of chlorozotocin that produced optimal in vivo L1210 antitumor activity was one-third to one-half that of CCNU. Chlorozotocin, unlike CCNU, produced no murine bone marrow toxicity at its optimal therapeutic dose. This unique combination of antitumor activity without myelosuppression can be correlated with the advantageous ratio of L1210:bone marrow in vitro DNA alkylation by chlorozotocin (1.3) as compared to equimolar CCNU (0.6).
 ...
PMID:Chlorozotocin. Mechanism of reduced bone marrow toxicity in mice. 15 33

The newly synthesized nitrosoureas 1-(2-chloroethyl)-1-nitroso-3-(methylenecarboxamido)-urea (Acetamido-CNU), 1-(2-chloroethyl)-1-nitroso-3-(4-morpholino)-urea (Morpholino-CNU), 1-(2-chloroethyl)-1-nitroso-3-(1-piperidino)-urea (Piperidino-CNU), and 2-[3-(2-chloroethyl)-3-nitrosoureido]-ethylmethanesulfonate (Ethylmethanesulfonato-CNU) were compared in their chemotherapeutic activity against preterminal rat leukemia L 5222 with BCNU, CCNU, MeCCNU, Chlorozotocin, and Hydroxyethyl-CNU. With respect to the dose range effecting a median survival time of more than 90 days, MeCCNU was superior to the other substances. Chlorozotocin, on the other hand, was the only substance which achieved no cures in this experimental arrangement. From the four newly introduced substances the water-soluble substances Acetamido-CNU and Morpholino-CNU were approximately comparable to CCNU with regard to the dose range effecting a median survival time of greater than 90 days. Piperidino-CNU and Ethylmethanesulfonato-CNU also effected cures; however, only Piperidino-CNU in one dosage effected a median survival time of greater than 90 days.
 ...
PMID:Examination of four newly synthesized 2-chloroethylnitrosoureas in comparison with BCNU, CCNU, MeCCNU, chlorozotocin and hydroxyethyl-CNU in preterminal rat leukemia L 5222. 15 9

The removal of DNA adducts is an essential step of DNA repair following exposure to chloroethylnitrosoureas. Adduct removal was evaluated in both L1210 and murine bone marrow DNA for lesions induced by three chloroethylnitrosoureas. 1-(2-Chloroethyl)-3-cyclohexyl-1-nitrosourea, a marrow-toxic agent with high carbamoylating activity, was not removed in either system for at least 6 to 12 hr. These results were compared with those obtained with two glucose-linked chloroethylnitrosoureas, chlorozotocin and 1-(2-chloroethyl)-3-(beta-D-glucopyranosyl)-1-nitrosourea. Both of these agents have low marrow toxicity at therapeutic doses. Chlorozotocin, which has very low chemical carbamoylating activity, was found to permit approximately 40% removal of drug-derived DNA adducts in both systems within the first 6 hr and approximately 50% by 18 hr. The second glucose-linked analog, 1-(2-chloroethyl)-3-(beta-D-glucopyranosyl)-1-nitrosourea, has relatively high carbamoylating activity and was found to inhibit early removal of DNA adducts as effectively as does 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea. It would thus appear that the selective marrow-sparing property of the sugar-linked chloroethylnitrosoureas is not dependent upon carbamoylation-mediated differences in the rate and extent of DNA adduct removal. In view of the comparable therapeutic activity of the three drugs for L1210 leukemia, therapeutic efficacy does not appear to be impaired by the increased rate of adduct removal observed with chlorozotocin in this system.
 ...
PMID:Repair of DNA alkylation induced in L1210 leukemia and murine bone marrow by three chloroethylnitrosoureas. 621 Dec 25

Chlorozotocin is a glucose-substituted chloroethyl nitrosourea with pharmacologic properties suggesting it is a relatively nonmyelosuppressive cancer chemotherapy drug. Preclinical studies have shown that this drug possesses approximately twice the in vitro alkylating activity of the chloroethyl nitrosoureas BCNU and CCNU. In the L1210 leukemia system, chlorozotocin has curative activity at doses that result in minimal bone marrow toxicity. In vitro studies of human bond marrow stem cells have shown that chlorozotocin is relatively sparing of these cells compared to BCNU. Phase I and phase II trials in man have been performed that show that chlorozotocin's dose-limiting toxicity is thrombocytopenia at doses greater than 120 mg/m2. In the phase II trial, 16% of patients with colon cancer and 20% of patients with malignant melanoma evidenced objective regression of disease. Chlorozotocin is now undergoing phase II evaluation in combination chemotherapy trials in colon and stomach cancer.
 ...
PMID:Preclinical and clinical studies on chlorozotocin, a new nitrosourea with decreased bone marrow toxicity. 644 66