An added dimension: will three-dimensional cultures improve our understanding of drug resistance?
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Animals↗
Biomedical subjects
M R Grever
Publications and source records attributed to M R Grever.
HLA-DR-, CD33+, CD56+, CD16- myeloid/natural killer cell acute leukemia: a previously unrecognized form of acute leukemia potentially misdiagnosed as French-American-British acute myeloid leukemia-M3.
We have identified and characterized a previously unrecognized form of acute leukemia that shares features of both myeloid and natural killer (NK) cells. From a consecutive series of 350 cases of adult de novo acute myeloid leukemia (AML), we identified 20 cases (6%) with a unique immunophenotype: CD33+, CD56+, CD11a+, CD13lo, CD15lo, CD34+/-, HLA-DR-, CD16-. Multicolor flow cytometric assays confirmed the coexpression of myeloid (CD33, CD13, CD15) and NK cell-associated (CD56) antigens in each case, whereas reverse transcription polymerase chain reaction (RT-PCR) assays confirmed the identity of CD56 (neural cell adhesion molecule) in leukemic blasts. Although two cases expressed CD4, no case expressed CD2, CD3, or CD8 and no case showed clonal rearrangement of genes encoding the T-cell receptor (TCR beta, gamma, delta). Leukemic blasts in the majority of cases shared unique morphologic features (deeply invaginated nuclear membranes, scant cytoplasm with fine azurophilic granularity, and finely granular Sudan black B and myeloperoxidase cytochemical reactivity) that were remarkably similar to those of acute promyelocytic leukemia (APL); particularly the microgranular variant (FAB AML-M3v). However, all 20 cases lacked the t(15;17) and 17 cases tested lacked the promyelocytic/retinoic acid receptor alpha (RAR alpha) fusion transcript in RT-PCR assays; 12 cases had 46,XX or 46,XY karyotypes, whereas 2 cases had abnormalities of chromosome 17q: 1 with del(17)(q25) and the other with t(11;17)(q23;q21) and the promyelocytic leukemia zinc finger/RAR alpha fusion transcript. All cases tested (6/20), including the case with t(11;17), failed to differentiate in vitro in response to all-trans retinoic acid (ATRA), suggesting that these cases may account for some APLs that have not shown a clinical response to ATRA. Four of 6 cases tested showed functional NK cell-mediated cytotoxicity, suggesting a relationship between these unique CD33+, CD56+, CD16- acute leukemias and normal CD56+, CD16- NK precursor cells. Using a combination of panning and multiparameter flow cytometric sorting, we identified a normal CD56+, CD33+, CD16- counterpart cell at a frequency of 1% to 2% in the peripheral blood of healthy individuals. Our studies suggest that this form of acute leukemia may arise from transformation of a precursor cell common to both the myeloid and NK cell lineages; thus we propose the designation myeloid/NK acute leukemia. Recognition of this new leukemic entity will be important in distinguishing these ATRA-nonresponsive cases from ATRA-responsive true APL.
Acute Disease↗
Biodistribution of O6-benzylguanine and its effectiveness against human brain tumor xenografts when given in polyethylene glycol or cremophor-EL.
O6-Benzylguanine effectively inactivates the DNA-repair protein O6-alkylguanine-DNA alkyltransferase in tumor cells and has been shown to increase the cytotoxicity of chloroethylnitrosoureas. This study was undertaken to ascertain the optimal vehicle for further toxicological evaluation and eventual clinical trials of O6-benzylguanine. The solubility, metabolism, bioavailability and effectiveness of O6-benzylguanine as an adjuvant therapy with BCNU were compared using two vehicles, cremophor-EL and PEG 400. Nude mice bearing s.c. D456 MG glioblastoma xenografts were injected i.p. with 10-30 mg/kg O6-benzylguanine dissolved in either 40% PEG 400/saline or 10% cremophor-EL/saline. The number of tumor regressions noted after treatment with 10 mg/kg O6-benzylguanine followed by 12.7 mg/kg BCNU were 8/9 for the drug dissolved in PEG and 1/10 for the drug given in cremophor-EL. Using the same treatment regimen but increasing the dose of O6-benzylguanine to 30 mg/kg led to a growth delay of 45.2 and 11.5 days for the drug dissolved in PEG 400 and cremophor-EL, respectively, although the number of regressions observed were the same for both treatments. 8-[3H]-O6-Benzylguanine was more rapidly distributed to the tumor when it was delivered in PEG vehicle than when it was given in cremophor-EL. In contrast, there was a 3-fold greater amount of O6-benzylguanine in the small intestine of mice at 1 h after i.p. injection of the drug in cremophor-EL as compared with PEG 400. The rate and extent of metabolism in the liver was the same, whether the parent drug was given in PEG 400 or in cremophor-EL. These studies demonstrate that O6-benzylguanine is a more effective enhancer of the antitumor activity of BCNU when it is given in PEG 400 than when it is delivered in cremophor-EL, which may be due to a more rapid distribution of the drug to the tumor.
Adjuvants, Pharmaceutic↗
A Southwest Oncology Group phase II evaluation of fluderabine monophosphate in sarcoma.
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Antimetabolites, Antineoplastic↗
The taxol supply crisis. New NCI policies for handling the large-scale production of novel natural product anticancer and anti-HIV agents.
Over the past 30 years, the National Cancer Institute has been involved in the preclinical and/or clinical evaluation of the majority of those agents approved for the treatment of cancer. Many of the new agents under consideration in the NCI program are either natural products or derivatives of natural product leads, and of critical importance to their development is the issue of drug supply. In responding to the drug supply crisis which emerged with the demonstration of the clinical efficacy of taxol, the NCI has identified several important lessons for those interested in natural product drug discovery and development. As a result, the NCI has developed plans to avert similar supply crisis in the future by initiating exploratory research projects for large-scale production of promising agents at the earliest possible point following the demonstration of confirmed antitumor activity. These plans, together with a review of the development of taxol, are presented in this paper.
Antineoplastic Agents↗
A phase I trial of combination fludarabine monophosphate and chlorambucil in chronic lymphocytic leukemia: a Southwest Oncology Group study.
Fludarabine monophosphate is a new antimetabolite with demonstrated activity in chronic lymphocytic leukemia (CLL). We have investigated the practicality of utilizing fludarabine in combination with chlorambucil in a disease-specific phase I trial. Twenty-one patients with advanced and previously treated, relapsed or refractory CLL were treated with chlorambucil plus fludarabine. Chlorambucil was given day 1 at 15 or 20 mg/m2 per os and fludarabine days 1-5 at 10, 15, or 20 mg/m2 intravenously, every 28 days. We concluded that with chlorambucil 15 mg/m2, the maximum tolerated dose for fludarabine was 20 mg/m2 in this patient population with this scheduling. Dose-limiting toxicity was thrombocytopenia. A low incidence of peripheral neuropathy, rash, pulmonary fungal infection, and acute tumor lysis syndrome was also encountered. Although responses were observed, it was impossible from this study to determine whether the combination was better than fludarabine alone in this heavily pretreated population. This study does, however, demonstrate the feasibility of exploring the utility of such a combination in previously untreated patients. An intergroup phase III trial utilizing this combination has been initiated.
Administration, Oral↗
Neural computing in cancer drug development: predicting mechanism of action.
Described here are neural networks capable of predicting a drug's mechanism of action from its pattern of activity against a panel of 60 malignant cell lines in the National Cancer Institute's drug screening program. Given six possible classes of mechanism, the network misses the correct category for only 12 out of 141 agents (8.5 percent), whereas linear discriminant analysis, a standard statistical technique, misses 20 out of 141 (14.2 percent). The success of the neural net indicates several things. (i) The cell line response patterns are rich in information about mechanism. (ii) Appropriately designed neural networks can make effective use of that information. (iii) Trained networks can be used to classify prospectively the more than 10,000 agents per year tested by the screening program. Related networks, in combination with classical statistical tools, will help in a variety of ways to move new anticancer agents through the pipeline from in vitro studies to clinical application.
Alkylating Agents↗
Analysis of treatment failure in acute nonlymphocytic leukemia patients over fifty years of age. A Southwest Oncology Group study.
Fourteen participating centers registered 33 patients on a Southwest Oncology Group Study of adults with acute non-lymphocytic leukemia (ANLL). Induction consisted of cytosine arabinoside 70 mg/m2 days 1-7 by continuous intravenous (i.v.) infusion, VP-16 50 mg/m2 i.v. over 1 hour days 1-3, and daunomycin 30 mg/m2 i.v. bolus days 1-3. Twenty-five patients (median age 69 years) were evaluable for response. Eleven (44%) achieved a remission marrow but only 8 fulfilled both blood and marrow criteria for complete remission. Of the 11 patients with a remission marrow, there were no patients over 70 years of age. Major coexisting disease data were evaluated. Only 5 patients had no major coexisting disease and 4 of those 5 achieved a remission marrow. The study illustrates and underscores the following problems of remission induction in the elderly: (a) increased susceptibility to the stress of the induction period, with 6 patients (24%) dying before treatment day sixteen; (b) disease resistance to antileukemic therapy with persistent ANLL in 6 patients (24%), despite two induction courses; and (c) hematopoietic stem cell sensitivity in the elderly with marrow regeneration failure documented in 2 patients (8%) following induction. Acute nonlymphocytic leukemia in the elderly has a poor prognosis, and novel therapeutic approaches are warranted.
Aged↗
The National Cancer Institute: cancer drug discovery and development program.
The discovery and development of novel therapeutic products for the treatment of malignancy is vitally important to those physicians responsible for the management of cancer patients. A description of the ongoing efforts at the National Cancer Institute (NCI) is intended to provide insight into those complex processes necessary to accomplish this mission. An update on the NCI's revised cancer screen is accompanied by a brief summary of those new agents scheduled to be entered into clinical investigation in the near future. The tremendous potential advantages and challenges associated with the use of a molecular approach to cancer drug design are discussed. Despite the differences of opinion that may exist regarding the optimal strategies for accomplishing the mission, there is no disagreement regarding the importance of the effort to find effective new therapies for cancer patients.
Animals↗
Summary of the workshop on Drug Development, Biological Diversity, and Economic Growth.
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Developing Countries↗
Queuine, a tRNA anticodon wobble base, maintains the proliferative and pluripotent potential of HL-60 cells in the presence of the differentiating agent 6-thioguanine.
6-Thioguanine (6-TG)-induced differentiation of hypoxanthine phosphoribosyltransferase (IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8)-deficient HL-60 cells is characterized by 2 days of growth, after which morphological differentiation proceeds. Addition of the tRNA wobble base queuine, in the presence of 6-TG, maintains the proliferative capability of the cells. The ability of 6-TG to induce differentiation correlates with c-myc mRNA down-regulation, but queuine has no effect on this parameter. Treatment with 6-TG for 2-3 days commits HL-60 cells to granulocytic differentiation, and, once committed, these cells do not respond to the monocytic inducer phorbol 12-myristate 13-acetate. Nonetheless, when cells are treated with queuine and 6-TG, they maintain the promyelocytic morphology and are capable of being induced down the monocytic pathway by phorbol 12-myristate 13-acetate as indicated by stabilization of c-fms mRNA and cell adherence. In the absence of queuine, phorbol 12-myristate 13-acetate is incapable of inducing monocytic markers in the 6-TG-treated cells. The data presented indicate that 6-TG-induced differentiation of HL-60 cells is a tRNA-facilitated event and that the tRNA wobble base queuine is capable of maintaining both the proliferative and pluripotent potential of the cells.
Anticodon↗
Cardiac complications observed in elderly patients following 2'-deoxycoformycin therapy.
Deoxycoformycin (dCF) is an investigational nucleoside with significant activity in hairy cell leukemia, cutaneous T-cell lymphoma, and chronic lymphocytic leukemia. During a 4-year period, 11 patients have experienced cardiac events as a complication of dCF therapy under NCI sponsorship. The cases are presented and recommendations for the administration of dCF to patients with pre-existing heart disease are made.
Aged↗
Phase II investigation of pentostatin in multiple myeloma: a Southwest Oncology Group study.
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Aged↗
Immunological effects of flavone acetic acid.
Flavone acetic acid (FAA) enhances natural killer and lymphokine-activated killer (LAK) cell activity in mice. We examined the immunological effects of FAA on human blood cells both in vivo and in vitro. Peripheral blood natural killer and LAK activity and lymphocyte subsets were evaluated in cancer patients after receiving 3-h infusion of FAA at either 8.5 or 10 g/m2 with alkalinization. Natural killer cell activity and the number of Leu-19 (CD56) positive cells decreased at 24 h after infusion; significant changes in LAK activity and the number of Leu-1 (CD5), Leu-3 (CD4), Leu-2 (CD8) cells were not observed. Peripheral blood mononuclear cells and peripheral blood lymphocytes collected from healthy volunteers were exposed in vitro to FAA, interleukin 2, and FAA plus interleukin 2. FAA, alone or in combination, failed to enhance LAK activity at any time point or concentration from peripheral blood mononuclear cells and peripheral blood lymphocytes. Concentrations of greater than or equal to 100 micrograms/ml antagonized the generation of LAK activity from interleukin 2 treated peripheral blood lymphocytes. These data suggest that FAA may not be useful in enhancing immunological responses in humans.
Adult↗
Phase II study of fludarabine phosphate in multiple myeloma. A Southwest Oncology Group study.
Thirty-one patients with multiple myeloma refractory to therapy or relapsing after response to initial therapy were treated with Fludarabine Phosphate utilizing a daily intravenous schedule for five consecutive days. There were no objective responses seen and only one patient showed clinical improvement. Myelosuppression manifest as leucopenia and granulocytopenia was the primary toxicity seen. Fludarabine Phosphate is inactive in previously treated myeloma patients when given by the daily intravenous route.
Adult↗
Differential effect of 6-ethylmercaptopurine on c-myc expression in wild-type and HGPRT-deficient HL-60 cells.
A variety of compounds inhibit the growth and induce differentiation of human promyelocytic leukemia (HL-60) cells. HL-60 subclones that lack the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) can also be induced to differentiate with purine analogs. Mechanisms by which purine analogs induce differentiation offer unique possibilities for cancer chemotherapy. We have studied the effect of the purine analog 6-ethylmercaptopurine (e6MP) on the growth and induction of differentiation in both wild-type and HGPRT-deficient HL-60 cells. We have previously shown that e6MP inhibits cell growth in both wild-type and HGPRT-deficient HL-60 cells without activation through salvage pathways. In this report we evaluate the effect of e6MP on c-myc mRNA expression. c-Myc mRNA, which is amplified in HL-60 cells, has been shown to play a role in the induction of granulocytic differentiation in HL-60 cells. e6MP transiently down-regulates c-myc mRNA in wild-type cells but has no effect on c-myc mRNA expression in HGPRT-deficient HL-60 cells. Despite the differential effects of e6MP on c-myc mRNA, both wild-type and HGPRT-deficient HL-60 cells appear to engage in terminal differentiation. The morphological changes and nonspecific esterase activity induced by e6MP suggest differentiation down the monocytic pathway. However, early monocytic markers such as the rapid induction of c-fos and the stabilization of c-fms mRNA are not observed. In addition, e6MP inhibits TPA-induced monocytic/macrophage differentiation as characterized by stabilization of c-fms mRNA and cellular adherence.
Cell Differentiation↗
Combined effects of interferon and 2'-deoxycoformycin on 2',5'-oligoadenylate synthetase and adenosine deaminase in hairy cell and chronic lymphocytic leukemia cells.
The combined effects of interferon (IFN) and 2'-deoxycoformycin (DCF) on 2',5'-oligoadenylate (2-5A) synthetase and adenosine deaminase (ADA) activity were examined in vitro in peripheral blood mononuclear cells from patients with hairy cell leukemia (HCL) and chronic lymphocytic leukemia (CLL). In HCL cells, the effects of IFN and DCF on both OAS and ADA activity were strictly antagonistic. Antagonism in inducing OAS activity was also observed in CLL cells, although, in general, little interaction between DCF and IFN occurred in these cells. If OAS and ADA are important in the antitumor effects of IFN and DCF, our results suggest that combination therapy with IFN and DCF could be counterproductive.
2',5'-Oligoadenylate Synthetase↗
Phase I trial and biochemical evaluation of tiazofurin administered on a weekly schedule.
Tiazofurin (2-B-D-Ribofuranosylthiazole-4-Carboxamide: NSC 286193) is a nucleoside antimetabolite that acts as a potent inhibitor of IMP dehydrogenase resulting in a guanine nucleotide deprivation. Recent in vivo biochemical observations in rats bearing hepatoma suggested a correlation between depletion of guanine nucleotides and antitumor effect. The present phase I trial utilized a weekly x 3 bolus infusion schedule, repeated every 5 weeks. Biochemical measurements of GTP and dGTP were performed in patients at each dose level. Twelve patients received 16 courses of the drug in doses ranging from 1100 to 2050 mg/m2 weekly x 3. The dose limiting toxicities were pericarditis and clinical symptoms suggestive of a more generalized serositis (chest and abdominal pain). Other toxicities included reversible elevations in CPK (MM band only) and SGOT, nausea, vomiting, and arthralgias. Neurotoxic effects were generally mild, including headaches, anxiety, and malaise. Only 1 of 6 patients evaluated for tiazofurin's biochemical activity showed a sustained depletion of guanine nucleotide pools. No antitumor activity was observed. The maximally tolerated dose of tiazofurin on this intermittent weekly x 3 schedule was 1650 mg/m2. Toxicity and the overall lack of biochemical and biologic effect at clinically achievable doses may preclude further clinical evaluation of this drug on a weekly schedule. The toxicities observed in our study were similar to those reported for phase I investigations using a considerably higher dose intensity with daily x 5 schedules.
Aged↗