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Many tumors overexpress the NQO1 gene, which encodes DT-diaphorase (NADPH:quinone oxidoreductase; EC 1.6.99.2). This obligate two-electron reductase deactivates toxins and activates bioreductive anticancer drugs. We describe the establishment of an isogenic human tumor cell model for DT-diaphorase expression. An expression vector was used in which the human elongation factor 1alpha promoter produces a bicistronic message containing the genes for human NQO1 and puromycin resistance. This was transfected into the human colon BE tumor line, which has a disabling point mutation in NQO1. Two clones, BE2 and BE5, were selected that were shown by immunoblotting and enzyme activity to stably express high levels of DT-diaphorase. Drug response was determined using 96-h exposures compared with the BE vector control. Functional validation of the isogenic model was provided by the much greater sensitivity of the NQO1-transfected cells to the known DT-diaphorase substrates and bioreductive agents streptonigrin (113- to 132-fold) and indoloquinone EO9 (17- to 25-fold) and the inhibition of this potentiation by the DT-diaphorase inhibitor dicoumarol. A lower degree of potentiation was seen with the clinically used agent mitomycin C (6- to 7-fold) and the EO9 analogs, EO7 and EO2, that are poorer substrates for DT-diaphorase (5- to 8-fold and 2- to 3-fold potentiation, respectively), and there was no potentiation or protection with menadione and tirapazamine. Exposure time-dependent potentiation was seen with the diaziquone analogs methyl-diaziquone and RH1 [2, 5-diaziridinyl-3-(hydroxymethyl)-6-methyl-1,4-benzoquinone], the latter being an agent in preclinical development. In contrast to the in vitro potentiation, there was no difference in the response to mitomycin C when BE2 and BE vector control were treated as tumor xenografts in vivo. This isogenic model should be valuable for mechanistic studies and bioreductive drug development.

Ataxia-telangiectasia (A-T) is a rare recessive disease characterised by cerebellar ataxia, immunodeficiency, sensitivity to ionising radiation and increased cancer risk. Heterozygotes have an increased risk of cancer and may comprise 1% of the population. In vitro, A-T heterozygote cell lines show radiosensitivity intermediate between normal and A-T homozygotes. Furthermore, in A-T homozygotes, hypersensitivity to chemical agents which cause DNA damage, similar to that produced by ionising radiation, has been observed. To investigate the chemosensitivity of A-T heterozygote cell lines, we used TUNEL to analyse the level of apoptosis after drug treatment with etoposide and streptonigrin. Our samples included four normal, eight A-T heterozygote and 10 A-T homozygote lymphoblastoid cell lines. All cell lines were exposed to drugs for 24 h, then cultivated in fresh media for 0 and 72 h. The levels of apoptosis increased significantly in all cell lines, with the greatest increase in homozygote cells and an intermediate increase in heterozygote cells (P values of < 0.01 for etoposide treatment and < 0.02 for streptonigrin treatment were obtained using the Kruskal-Wallis H-test). Our results indicate that A-T heterozygotes express intermediate sensitivity to etoposide and streptonigrin similar to that observed in response to ionising radiation.

A group of substituted 5,8-quinolinequinones which exhibit antineoplastic activity and which are structurally related to the antitumor antibiotic streptonigrin induce single strand cleavage of PM2 covalently-closed circular-DNA (ccc-DNA) when reductively activated. The cleavage which is detected by an ethidium fluorescence assay is specifically enhanced by cuprous and ferrous ion and is selectively inhibited by superoxide dismutase (EC 1.15.1.1) and catalase (EC 1.11.1.6) and by free radical scavengers. Independent generation of the superoxide ion by xanthine-xanthine oxidase (EC 1.2.3.2) also cleaves PM2 DNA and therefore a chemical mechanism for the scission process induced by the streptonigrin analogues is formulated. A correlation between rate of PM2 ccc-DNA cleavage and inhibition of Walker carcinosarcoma 256 is observed.

A tentative evaluation is proposed for the clinical status of 15 early and investigational drugs in human solid tumors.

We report here two randomized prospective clinical trials of adjuvant treatment in the management of primary malignant melanoma of Clark's level III, IV or V. All patients had curative resection of the primary tumor. In the first trial, 117 patients were randomized between control (surgery alone) systemic chemotherapy and intraarterial chemotherapy. Intraarterial chemotherapy consisted of DTIC 80 mg/m2 + 8 days prior to surgery. Systemic chemotherapy consisted of courses of vinblastine (6 mg/m2), thiotepa (6 mg/m2), rufocromycine (60 microgram/m2), methotrexate (15 mg/m2) on day 1, and procarbazine (30 mg/m12 X 7 days. Courses were repeated every 2 weeks X 6, then every 4 weeks X 15. Twenty-two of 55 patients relapsed in the control group versus 22 of 67 in the chemotherapy group (NS). For male patients, the difference in disease-free survival was significant (P less than 0.005, log rank test), though not in women. In the second trial, 352 patients were entered from July, 1976. Men were randomized between chemotherapy and chemoimmunotherapy. Women were randomized between surgery alone and chemoimmunotherapy. Chemotherapy was identical, except for the addition of DTIC (300 mg/m2) for each course. Immunotherapy consisted of BCG every 4 weeks and C. parvum every week. Immunotherapy seemed to be of no additional benefit.

A cytogenetic analysis of variants of Fisher mouse lymphadenosis L-5178 resistant to the antitumoral antibiotics bruneomycin and rubomycin C showed that the cytogenetic characteristics of the changes in the tumor cell population correlate with the chemotherapeutic indices of the development of drug resistance. Cytogenetic and kinetic analyses showed that variants of Fisher lymphadenosis L-5178 resistant to bruneomycin and rubomycin C retain sensitivity to N-nitrosomethylurea (NMU). The activity of NMU in an experiment on resistant substrains of lymphadenosis can serve as a basis for the clinical use of NMU in the treatment of lymphomas resistant to antibiotics.

Based on characteristic features of the toxic effect of chemotherapeutic drugs, these were selected for chemotherapy of experimental tumors. The reliable results were obtained in three variants of combinations. 1) A combined administration of drugs active with respect to one and the same tumor but which toxic effect do not coincide. 2) Simultaneous administration of two drugs in doses tolerable for gaining a therapeutic effect, obtained in their separate use in massive doses, but with a less toxic damage to the body. 3) A combination of substances possessing a selective toxic action on the tissue bearing the tumor under treatment.

This paper presents an overview of four Cancer and Leukemia Group B studies in 1266 patients with stage III-IV non-Hodgkin's lymphoma. The cases were analyzed across protocols; the major prognostic determinants were prior chemotherapy, age, and histology. The four studies proved that cyclophosphamide maintenance was superior to no maintenance even after prolonged intensive induction chemotherapy. Furthermore, the reinforcement program of monthly pulse doses of vincristine and prednisone, whose value was established in the treatment of acute leukemia, led to highly significant improvement in remission duration and survival. Other facets of the chemotherapy programs are still being subjected to analysis, but this report sets out some preliminary conclusions.

The effectivity of a combined application of Bruneomycin, Cytostasane and Prednisone has been tested in five qualitatively different experimental animal test models. The selected dose levels and the treatment schedule were based on an instruction given in a phase III-study. No effectivity was demonstrable in any of the tumor systems selected neither with the single components, nor with their combination, though the toxicity clearly revealed a dose dependence.

In this retrospective study the effect of combined chemotherapy on survival of patients with Hodgkin's disease is investigated. Among 125 cases observed between 1959 and 1973, the survival, response rate and duration of remission of patients treated with single drugs are compared with the same parameters in those treated by polychemotherapy. Further, since the combined treatment schedule was introduced in our group in 1969, survival of patients treated before and after this date is likewise compared. 35% of patients in the single drug group survived for more than 2 years, against 69% in the polychemotherapy group. At 3-year survival, the corresponding values were 12% and 61% respectively. For patients treated before 1969, survival of 2 and 3 years represents 45% and 22%. For patients treated from 1969 to 1973, the corresponding values are 61% and 51%. Rates of complete response are 20% for single drug treatments and 70% for combined treatments. Analysis of the results suggests that these differences correspond to the therapeutic superiority of combined chemotherapy in the treatment of Hodgkin's disease and not to major discrepancies in prognostic factors among the patient groups compared.

The preparation and evaluation of 7-amino-5,8-dioxo-2-(2'-pyridyl)quinoline-6'-carboxylic acid (5a) and 7-amino-2-(2'-aminophenyl)-5,8-dioxoquinoline-5'-carboxylic acid (6a) constituting potential minimum, potent pharmacophores of streptonigrin (1a) and lavendamycin (2a), two structurally related naturally occurring antitumor antibiotics, are detailed. In contrast to observations associated with streptonigrin and lavendamycin in which the C-ring C-6' carboxylic acid potentiates the antitumor, antimicrobial, and cytotoxic properties of the naturally occurring, substituted 7-aminoquinoline-5,8-dione AB ring systems, the C-6'/C-5' carboxylic acid of 5a/6a diminishes the observed antimicrobial and cytotoxic properties of the 2-(2'-pyridyl)- and 2-(2'-aminophenyl)-7-aminoquinoline-5,8-diones. A direct comparison of the antimicrobial and cytotoxic properties of a complete set of streptonigrin and lavendamycin partial structures is detailed in efforts to define the role peripheral substituents play in potentiating the biological properties of the naturally occurring and synthetic agents bearing the 7-aminoquinoline-5,8-dione AB ring system and in efforts to define the minimum, potent pharmacophore of the naturally occurring antitumor antibiotics. The relationship of these observations to a chemical mechanism of cellular toxicity is discussed.

The therapeutic activity of narcissus alkaloid pretazettine HC1 (PTZ) on established Rauscher leukemia has been demonstrated and compared with the isomer tazettine (TZ) and an antibiotic, streptonigrin (SN). PTZ and SN showed remarkable prolongation effect on the life span of the leukemic mice and the antiviral activity has been confirmed in mouse 3T3 cells infected with Rauscher virus. TZ showed no significant activity in the leukemic mice and was inhibitory to the virus growth in the cells at much higher doses than PTZ. It is suggested that the stereochemical rearrangement from PTZ to TZ inactivates the biological activity of PTZ.