Phase I trial and pharmacokinetic studies of alpha-difluoromethylornithine--an inhibitor of polyamine biosynthesis

alpha-Difluoromethylornithine (DFMO), an enzyme-activated, irreversible inhibitor of ornithine decarboxylase, blocks polyamine biosynthesis and has antitumor effects in animal tumor models as well as in athymic mice implanted with human small cell carcinoma. This study was designed to determine the maximally tolerated dose of oral DFMO administered every six hours for 28 days to patients with advanced solid tumors or lymphomas. DFMO levels were measured using an ion exchange chromatographic assay and pharmacokinetic studies were performed in patients treated at each dose level. Twenty-two patients received 24 courses of DFMO. The drug was generally well tolerated. Thrombocytopenia was the dose-limiting toxicity and gastrointestinal side effects were also seen. Thrombocytopenia developed in 11 of 16 patients who had received prior chemotherapy but the four patients who had no prior chemotherapy had no decrease in the platelet count. The steady state level of DFMO achieved at the highest dose (3 g/m2) were found to be within the range needed for inhibition of ornithine decarboxylase in cell-culture systems as well as for the inhibitory activity against various human tumors in vitro. A DFMO dose of 2.25 g/m2 every six hours is recommended for phase II studies in patients previously treated with cytotoxic drugs.

6-azauridine triacetate induced hyper beta-alaninemia and its decrease by administration of pyridoxine

The effect of pyridoxine on 6-azauridine triacetate (6-AzUrd-TA) induced hyper beta-alaninemia was studied in New Zealand albino rabbits in three experiments. In each of the three experiments the animals were administered by gavage: Group 1 (Control), drinking water; Group 2, 6-AzUrd-TA; and Group 3, 6-AzUrD-TA with pyridoxine. While no beta-alanine was found in the control group or in pretreatment samples of the 6-AZUrd-TA and 6-AzUrd-TA + pyridoxine treated animals, high concentrations of this amino acid (191.0 +/- 91.6, 220.2 +/- 116.3, 103.2 +/- 64.4 nmol/ml) were found on the fourth and seventh days of 6-AzUrd-TA treatment with daily doses of 1.0 g/kg and 0.5 g/kg B.W. respectively. The drug induced hyper beta-alaninemia was significantly (p less than or equal to 0.05) reduced in all three experiments by simultaneous pyridoxine administration in daily doses of 50 mg/kg B. W. These results indicate, that daily repeated oral administration of 6-AzUrd-TA causes elevation of serum beta-alanine, which can be partially prevented by oral administration of pyridoxine. They also indirectly support the hypothesis, that 6-AzUrd-TA induced hyper beta-alaninemia is at least partially caused by the inhibition of beta-alanine degrading enzymes, that use pyridoxal phosphate as a coenzyme. Direct measurement of the enzyme activity is planned in our future studies.

Spirogermanium: a new drug with antimalarial activity against chloroquine-resistant Plasmodium falciparum

Spirogermanium, a new investigational drug of novel structure currently under clinical studies in various neoplastic diseases, has revealed significant in vitro activity against chloroquine-resistant (FCB, FTA, FVO) and sensitive (FSL, FUI, FH) strains of Plasmodium falciparum. Inhibition of the growth and maturation of parasites after 36-h exposures to Spirogermanium started at concentrations ranging from 2.48 to 9.9 nM/ml. These concentrations appear to be within the range of Spirogermanium plasma levels reported in clinical studies with this drug. Since its clinical toxicities are unusually low in comparison with other anticancer drugs, our results on its in vitro activity against Plasmodium falciparum indicate Spirogermanium is an antimalarial drug of entirely novel structure, active in resistant strains.

Spirogermanium: a new investigational drug of novel structure and lack of bone marrow toxicity

Spirogermanium (NSC 192965) is a new metallic investigational anticancer drug of novel heterocyclic structure. Although its mode of action has not been fully elucidated, it appears that spirogermanium is not a phase or cell cycle specific drug and inhibits DNA, RNA and protein synthesis, the protein synthesis being the most susceptible to this agent. Spirogermanium has shown cytotoxic activity in vitro against several human tumor cell lines at concentrations (1 micrograms/ml) that were also found toxic to the cultured rat neurons. Although spirogermanium has no effect on normal bone marrow colony forming cells in mice, dogs, or man, it has revealed cytotoxic activity in vitro against human myeloid leukemia cell line K 562 at clinically achievable concentrations. These in vitro findings, indicating selective cytotoxic activity against leukemic cells suggest this drug as a candidate for clinical studies in acute and chronic leukemias. Spirogermanium has revealed activity in vivo against intraperitoneally implanted Walker 256 sarcoma, 13762 mammary adenocarcinoma, and 11095 prostatic carcinoma in rats, but no antitumor activity in vivo was found in the murine tumors used in the past by the NCI screen (L 1210 and P 388 leukemia, B 16 melanoma, Lewis lung carcinoma). Spirogermanium is remarkable for its lack of bone marrow toxicity confirmed in preclinical toxicology and clinical studies; moderate, predictable, and reversible CNS toxicity is dose-limiting. Activity in malignant lymphoma, ovarian cancer, breast cancer, large bowel cancer, and prostatic cancer was reported in the clinical studies. The drug is currently under clinical investigation against the wide spectrum of solid tumors and malignant lymphomas. The dose of 80-120 mg/m2, given by 60' infusion three times a week, is currently used and tolerated in Phase II clinical studies. The recently introduced five days continuous infusion schedule has been also under clinical investigation and the doses of 250-300 mg/m2/day are recommended for Phase II studies. Of interest are results reported in this paper of spirogermanium in vitro preferential activity against the resistant strains of Plasmodium falciparum at clinically achievable concentrations suggesting this drug as a possible new antimalarial agent of novel structure.

Pharmacokinetic study of methyl glyoxal-bis-guanylhydrazone (methyl-GAG)

Using a paired ion exchange high pressure liquid chromatographic assay, pharmacokinetic evaluation of methyl glyoxal bis guanylhydrazone (methyl-GAG) was performed in nine male New Zealand albino rabbits following administration of a single intravenous bolus dose of 50 mg/kg B.W (550 mg/m2 BSA). Blood samples were collected before and at intervals of 5, 10, 15, 30 min and 1, 2, 3, 4, 6, 8, 12, 18, and 24 h after administration of the drug. The analysis of experimental data indicates a three compartment open model with first order elimination from the central compartment described by the equation Cpt = A.e-alpha t + B.e-beta t + C.e-gamma t, where A, B, C, are 107.985, 4.785, and 0.763 micrograms/ml, respectively. alpha, beta, gamma, are 5.466, 0.487, and 0.030 h-1, respectively, and T1/2 alpha, beta, gamma are 7.6, 85.3 min and 23.1 h, respectively. The mean volume of distribution in the central compartment Vc was 0.44 liters (1)/kg, volume of distribution Vdarea 30.326 1/kg, and the total body clearance 0.9097 1/kg/h. The existence of a long terminal plasma half life of methyl-GAG reported previously in human studies was also confirmed in experimental animals and may explain the cumulative toxicity of this drug.

Urine levels of N-[9-(beta-D-ribofuranosyl)purin-6-ylcarbamoyl]-L-threonine, N6-(delta 2-isopentenyl)adenosine, and 2'-O-methylguanosine as determined by radioimmunoassay for normal subjects and cancer patients

Radioimmunoassays (RIA) are presented for the evaluation of the levels of the following three modified nucleosides in human urine: 2'-O-methylguanosine (Gm), N6-(delta 2-isopentenyl)adenosine (i6A), and N-[9-(beta-D-ribofuranosyl)purin-6-ylcarbamoyl]-L-threonine (t6A). Competitive inhibition of the RIA was provided by 2 to 10 microliters of untreated urine and the sensitivity of each RIA was in the pmol range. Partial fractionation of urine indicated that the majority of inhibitory activity was in the fraction coeluting with a nucleoside standard. The amounts of nucleosides in 24-hr urine samples from eight normal subjects were 2.2 +/- 0.9 mg (S.D.) for t6A; 0.17 +/- 0.09 mg for Gm; and 0.050 +/- 0.019 mg for i6A. The levels of t6A, i6A, and Gm were also determined by RIA of urine samples of patients with lymphomas or solid tumors. Levels of t6A were significantly elevated for patients with lung cancer (p less than 0.001), non-Hodgkin's lymphoma (p less than 0.05), and other solid tumors (p less than 0.02) but not for patients with Hodgkin's disease. The RIA data on the other two nucleosides, i6A and Gm, showed no similarly significant variations. Increased levels of t6A in the cancerous state were substantiated by isolating the t6A fraction from the urine of normal subjects of patients with lung cancer and quantitating the amount by use of UV adsorption. These preliminary results indicate that RIA for t6A might be clinically useful by providing a complementary approach to the assessment of the levels of modified nucleosides by gas-liquid or high-performance-liquid chromatography.

Phase I clinical trial of spirogermanium

Spirogermanium is a new azaspirane antitumor agent, with the metal germanium substituted for a one-carbon moiety in the ring structure. This drug inhibits DNA and RNA synthesis in HeLa cells, is cytotoxic in vitro, and has curative in vivo antitumor activity against the ascitic Walker 256 carcinosarcoma in rats. No hematologic toxicity was recorded during the preclinical toxicologic evaluation. The principal clinical toxic effects observed in this phase I trial were neurologic, manifested as lethargy, dizziness, and ataxia, while a grand mal seizure was produced after an accidental overdose. There was no evidence of hematologic, renal, or hepatic toxicity. A partial response was achieved in a patient with a well-differentiated lymphocytic lymphoma. We recommend that phase II trials be conducted with a twice or thrice weekly dose of 50-80 mg/m2, administered in a 30-minute iv infusion.

An age-related coagulation disorder associated with experimental infection with infectious bursal disease virus

Specific-pathogen-free White Leghorn chickens were inoculated with a field strain of infectious bursal disease virus. One group (A) was inoculated at 17 days after the chicks were hatched, and the other groups (C and E) were inoculated at posthatch day 42. Blood samples were obtained for determination of clotting times (whole blood recalcification, prothrombin, and activated partial thromboplastin times), virus-neutralizing antibody, and total hemolytic complement. There were significant increases in clotting times for groups C and E at 3 and 5 days after they were inoculated. There were no significant increases in clotting times at 3 days after inoculation in the group A chickens (inoculated at 17 days after hatching). There were no significant decreases in total complement activity in any of these chickens (groups A, C, and E). This study indicates that the mortality and clinical symptoms observed in chickens experimentally infected with infectious bursal disease virus may be associated with a clotting abnormality because it was noted only in chickens that developed severe clinical disease (inoculated at 42 days after hatching) and was not noted in chickens that remained clinically normal (inoculated at 17 days).

[Comments on the problem of differential diagnosis of tumours of the nerve sheaths in angiography (author's transl)]

The article describes the special features governing the assessment of angiographic findings in tumours of the nerve sheaths. Considerations of differential diagnosis, especially between neurinoma and neurofibroma, are discussed. Likewise, the problems of differential diagnosis of such tumours against neoplasms of the tissue of the soft parts, are also discussed. Angiography permits only a limited determination of the degree of malignancy of the neurinoma and neurofibroma. It is always mandatory to correlate these findings with the histological findings. However, angiography does seem to be justified as an additional examination technique, since it supplies fundamental pointers for surgery.

Changes in amino acid metabolism caused by 6-azauridine triacetate: relevance to cancer treatment

6-Azauridine triacetate (6-AzUrd-TA) administration causes changes in amino acid metabolism both in experimental animals and in man. This effect is dose-related. Amino acid changes caused by 6-AzUrd-TA resemble those in inborn homocystinuria, beta-alaninemia, and hyperhistidinemia. Inhibition of certain enzymes using pyridoxal phosphate as a coenzyme appears to be the common denominator for these changes. There is supportive evidence suggesting that homocystinemia and thrombotic episodes, both caused by 6-AzUrd-TA, are related. These results also reveal that anticancer drugs other than amino acid analogs and amino acid-depleting enzymes may cause significant changes in amino acid metabolism. Their detection and correlation with the therapeutic or adverse effects can be used as an alternative method for studying the relevance of amino acid changes to the treatment of cancer.

Association of breast cancer with meningioma: report of two cases and review of the literature

We report two cases of breast cancer in whom meningioma subsequently developed and provide a brief review of the literature. A hormonal interrelationship is suggested. The knowledge of this potential association is important in the interpretation and treatment of patients with breast cancer who develop central nervous system manifestations.

Nature of the lectin-induced activation of plasma membrane Mg2+ATPase

The Mg2+ATPase activity of liver plasma membranes decreases markedly with increasing temperature above 30 degrees. This negative temperature dependency is counteracted by the binding of wheat germ agglutinin, concanavalin A, or Ricinus communis agglutinin (at concentrations greater than or equal 0.5 mg/ml) to membranes prior to assay of the enzyme. With one of these lectins bound, the enzyme has a single energy of activation between 20 degrees and 45 degrees. The binding of dimeric succinyl concanavalin A, soybean agglutinin, fucose-binding lectin from Lotus tetragonolobus, or the leucoagglutinin from Phaseolus vulgaris does not alter the temperature dependency of the enzyme. The latter two lectins, however, do prevent the concanavalin A-induced activation of the enzyme at 37 degrees. At saturating substrate concentrations, the enzyme is not inhibited by any of the lectins tested over a wide range of concentrations. Cytochalasin B and colchicine separately or in combination have little influence on the lectin-induced enhancement of enzyme activity. Chlorpromazine and vinblastine sulfate each partially prevent the activation and in combination do so completely. Treatment of the membranes with the detergent Lubrol-PX or phospholipase A prevents activation of the enzyme by concanavalin A. The results are consistent with a restriction by the lectin of an environment which is normally too disordered for maximal enzyme activity above 30 degrees.

Incidence of drug-related deaths secondary to high-dose methotrexate and citrovorum factor administration

A review of 498 patients treated with high-dose methotrexate (MTX) with citrovorum factor rescue revealed 29 drug-related deaths. Until the important factors in those deaths are identified, the use of high-dose MTX should be limited to institutions that possess the necessary supportive facilities and the ability to measure serum levels of the drug.

Cis-diamminedichloroplatinum (II). A new anticancer drug

Cis-diamminedichloroplatinum (II) (DDP) leads the series of platinum coordination complexes, a new class of cytotoxic agents. The antitumor and toxic effects of this drug are discussed. It has displayed encouraging results in testicular tumors. The drug's therapeutic effectiveness has also been recognized in a variety of other solid tumors, particularly ovarian, bladder, and head and neck malignancies. Gastrointestinal, renal, audiologic, and relatively minor hematologic toxicities may be encountered, but promising methods have been developed to increase the therapeutic index of DDP.