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PubMed2002

An assessment of the ayurvedic concept of cancer and a new paradigm of anticancer treatment in Ayurveda.

This paper critically examines the Ayurvedic concept of cancer diathesis and its pathogenesis in terms of the theory of Tridosa, Sapta Dhātus (body tissues), the Agni or body's biologic fire, Srotámsi (i.e., channels of the body), and the generic sequence of events in the genesis of a disease (e.g., Satkriyākala). All this depicts a new paradigm of the disease state. This paper also examines the scope of plant drugs used in the treatment of cancer. A retrospective meta-analysis of observations on 85 plant drugs reported to have an anticancer effect indicates that herbs with Katu, Tikta, Kasāya Rasa (bitter, pungent, and astringent taste), Usna Virya (e.g., hot biopotency), and Katu Vipāka (catabolic active metabolites), and herbs with dry, coarse, light, and sharp biophysical properties have significantly greater possibilities of producing anticancer effects.

Antineoplastic Agents, Phytogenic↗

PubMed2004

Germane facts about germanium sesquioxide: I. Chemistry and anticancer properties.

This paper reviews the history, chemistry, safety, toxicity, and anticancer effects of the organogermanium compound bis (2-carboxyethylgermanium) sesquioxide (CEGS). A companion review follows, discussing the inaccuracies in the scientific record that have prematurely terminated research on clinical uses of CEGS. CEGS is a unique organogermanium compound first made by Mironov and coworkers in Russia and, shortly thereafter, popularized by Asai and his colleagues in Japan. Low concentrations of germanium occur in nearly all soils, plants and animal life; natural occurrence of the CEGS form is postulated but not yet demonstrated. The literature demonstrating its anticancer effect is particularly strong: CEGS induces interferon-gamma (IFN-gamma), enhances natural killer cell activity, and inhibits tumor and metastatic growth--effects often detectable after a single oral dose. In addition, oral consumption of CEGS is readily assimilated and rapidly cleared from the body without evidence of toxicity. Given these findings, the absence of human clinical trials of CEGS is unexpected. Possible explanations of why the convincing findings from animal research have not been used to support clinical trials are discussed. Clinical trials on CEGS are recommended.

Animals↗

PubMed2002

Oblimersen Bcl-2 antisense: facilitating apoptosis in anticancer treatment.

The components of the apoptotic program are targets for anticancer therapy. Bcl-2 protein inhibits apoptosis and confers resistance to treatment with traditional cytotoxic chemotherapy, radiotherapy, and monoclonal antibodies (mAb). Oblimersen sodium (G3139, Genasense, Genta Inc., Berkeley Heights, NJ) is an antisense oligonucleotide (AS-ON) compound designed to specifically bind to the first 6 codons of the human bcl-2 mRNA sequence, resulting in degradation of bcl-2 mRNA and subsequent decrease in Bcl-2 protein translation. Oblimersen is the first oligonucleotide to demonstrate proof of principle of an antisense effect in human tumors by the documented downregulation of the target Bcl-2 protein. A growing body of preclinical and clinical evidence suggests that oblimersen synergizes with many cytotoxic and biologic/immunotherapeutic agents against a variety of hematologic malignancies and solid tumors. Randomized clinical trials are currently underway to evaluate the efficacy and tolerability of oblimersen in combination with cytotoxic chemotherapy in chronic lymphocytic leukemia, multiple myeloma, malignant melanoma, and non-small cell lung cancer. In addition, nonrandomized trials are under way to evaluate oblimersen in non-Hodgkin's lymphoma, acute myeloid leukemia, and hormone-refractory prostate cancer. Preclinical data also support the clinical evaluation of oblimersen in additional tumor types, including chronic myelogenous leukemia and breast, small cell lung, gastric, colon, bladder, and Merkel cell cancers. Enhancement of the efficacy of anticancer treatments with oblimersen Bcl-2 antisense therapy represents a promising new apoptosis-modulating strategy, and ongoing clinical trials will test this therapeutic approach.

Antineoplastic Agents↗

PubMed1999

Immune response to haptenized tumor antigen as possible mechanism of anticancer action of hypoxic bioreductive agents at low doses.

Possible anticancer effect mechanism of hypoxic bioreductive agents (HBA) at low nongenotoxic doses are reviewed. Experimental and clinical investigations show the process which can develop step-by-step when injecting HBA into the tumor-bearing organism resulting in the stimulation of antitumor immunity: HBA activation in hypoxic tumor tissue, conjugation of activated HBA with proteins of tumor cells, antigen processing, presentation of neoantigen epitops in association with major histocompatibility complex-I and cytolysis of these tumor cells by T-killers. The present process can be a variant of the delayed-type hypersensitivity reaction in the tumor region. The direct regulating influence of HBA on immunocompetent and/or tumor cells as a result of interaction of these drugs with superficial or intercellular receptors is supposed to be realized additively with this process. It is concluded that the ability of HBA to selective activation in tumor tissue and formation of immunogenic conjugates with tumor proteins can be a starting-point for developing drugs with immuno-modulation anticancer properties.

Adjuvants, Immunologic↗

PubMed1984

Calcium channel blocker enhancement of anticancer drug cytotoxicity--a review.

A review of the pharmacological background and clinical activity of different Ca2+ channel blockers concerning reversal of anticancer drug resistance in tumors suggests that verapamil and trifluoperazine may be the most immediate candidates. Reversal of resistance to anthracyclines and vinca alkaloids originally observed in mouse experimental leukemia cell lines has now been extended to other animal cell lines and human tumors as well. Evidence is available that resistance to drugs of other classes such as dactinomycin, etoposide, and mitoxantrone can be reversed by various calcium channel blockers. Apart from enhancing retention of anticancer drugs in tumor cells, little is actually known of the mechanism(s) by which this phenomenon occurs. There is inconclusive evidence for the role of Ca2+ ions and Ca2+ channel receptors in the process, and, furthermore, there is no evidence that Ca2+ channel blocking activity per se is necessary for the reversal of drug resistance.

Animals↗

PubMed1998

Altered sensitivities to anticancer and differentiation agents in etoposide-resistant human myeloid leukemia U-937 cells.

We previously have exposed U-937 human leukemia cells to stepwise increased concentrations of the anticancer drug etoposide, and this treatment has resulted in stable sublines (termed U-937/RE) exhibiting various extents of resistance to the drug and constitutively expressing c-fms mRNA, a specific marker of monocytic differentiation. In this report, we pursued studies to show that the P-glycoprotein blocker, verapamil, partially restores sensitivity to etoposide in U-937/RE cells. Further, the U-937/RE cells exhibit differential sensitivities to compounds that induce maturation of U-937 cells, as judged by the ability to reduce nitroblue tetrazolium and by morphologic changes, and increased sensitivities to apoptosis induction by the cytokines tumor necrosis factor (TNF) and lymphotoxin (LT) and the anticancer drugs 9-nitrocamptothecin and doxorubicin. In addition, the U-937/RE cells, xenografted in immunodeficient mice, demonstrate decreased or no ability to induce tumors. Taken together, these findings indicate that U-937/RE cells differ from the parental U-937 cells in several functional properties and can serve as models to develop protocols for treatment of human leukemia.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1989

A new in vitro screening system for anticancer drugs for the treatment of non-small cell lung cancer.

We have evaluated a semiautomated radiometric assay (BACTEC 460 system) for screening of activity of anticancer drugs against human non-small cell lung cancer cell lines. Cells from seven cell lines were exposed to standard antineoplastic agents at four different concentrations using a 1-h incubation. Alpha 2-interferon was tested using a continuous incubation. In vitro drug activity was analyzed as a function of the clinically achievable serum concentration. Our results indicate that two cell lines (CALU-3, SK-MES-1) exhibit in vitro drug sensitivity patterns closest to those observed in clinical studies. These two cell lines might therefore be most useful for screening new anticancer compounds for activity against non-small cell lung cancer. The radiometric assay is a semiautomated system which has advantages over other, more time-consuming screening systems.

Antineoplastic Agents↗

PubMed2004

Phosphorylation of FADD is critical for sensitivity to anticancer drug-induced apoptosis.

FADD has been shown to be phosphorylated at Ser194 at the G2/M transition of the cell cycle. Here we have investigated the contribution of this phosphorylation to apoptosis induced by anticancer drugs in two human prostate cancer cell lines, LNCaP and DU145. Both were arrested at G2/M and FADD was found to be phosphorylated at Ser194 on treatment with paclitaxel. Inhibition of paclitaxel-induced c-jun NH2-terminal kinase (JNK) activation by treatment with a specific inhibitor, SP600125, or overexpression of a dominant-negative mutant form of upstream kinases, MEK kinase 1 (MEKK1) and mitogen-activated protein kinase kinase (MKK) 7, significantly reduced the increase in phosphorylated FADD. It is noteworthy that pretreatment with paclitaxel significantly up-regulated MEKK1 expression, resulting in enhancement of etoposide- or cisplatin-induced MEKK1/MKK7-dependent JNK activation and apoptosis in LNCaP and DU145 cells. Interestingly, MEKK1 up-regulation and the synergistic effects of paclitaxel on anticancer drug-induced apoptosis were abolished by overexpression of mutant FADD (Ser194-->Ala). The results clearly show that FADD phosphorylation at Ser194 affects functions both upstream and downstream of the MEKK1/MKK7/JNK1 pathway and is closely associated with chemosensitivity in prostate cancer cells. This is the first report indicating that phosphorylated FADD plays an essential role in the mechanisms of amplifications of chemotherapy-induced apoptosis.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Characteristic expression of Lewis-antigenic glycolipids in human ovarian carcinoma-derived cells with anticancer drug-resistance.

By comparing ovarian carcinoma-derived KF28 cells with the corresponding anticancer drug-resistant cells, the taxol- and cisplatin-resistant properties were found to be closely related with MDR1 and BSEP, and MRP2 transporters, respectively. In addition to the transporters expression, the amounts of glycolipids, particularly their longer carbohydrate structures, in the resistant cells increased to 3-4-fold of those in the sensitive cells due to enhanced transcription of the respective glycosyltransferases. The major glycolipids in the sensitive and resistant cells were GlcCer and Gb(3)Cer, respectively, and extension of the carbohydrate structure into Lewis antigen characteristically occurred in the resistant cells. Le(b), which was not detected in the cisplatin-resistant cells, was present in the taxol-resistant cells, while Le(x) was present in the cisplatin-resistant cells at a higher concentration than in the taxol-resistant cells. 2-Hydroxy fatty acids were significantly abundant in glycolipids of the resistant cells, but they were not detected in free ceramides or sphingomyelin, indicating that the enhanced synthesis of glycolipids in the resistant cells was not linked with the removal pathway for virulent ceramides derived from sphingomyelin. The resistant cells with abundant glycolipids exhibited lower membrane fluidity than the KF28 cells, and this property might be involved in the anticancer drug-resistance.

Cisplatin↗

PubMed1980

Anticancer agents and antitrypanosomiasis activity in mice.

Of 303 compounds (66 active against cancer and 237 inactive against cancer) obtained from the Drug Synthesis and Chemistry Branch, Developmental Therapeutics Program, Division of Cancer Treatment, National Cancer Institute, Bethesda, Maryland, 25 were found to be active against Trypanosoma rhodesiense infections of ICR/Ha Swiss mice. Fifteen of these 25 compounds also had anticancer properties. The percentage of anticancer compounds found to have antitrypanosomiasis properties was 22.7. This percentage compares with 6% antitrypanosomiasis compounds among compounds selectecd by other methods.

Animals↗

PubMed1981

Growth characteristics of MOPC-315 plasmacytoma and response to anticancer agents.

We examined the growth characteristics and response to anticancer agents of the murine plasmacytoma MOPC-315, a rapidly growing and widely disseminating tumor syngeneic in BALB/c mice. The doubling time for the tumor was approximately 24 hours, and about 1 in 100 cells was tumorigenic. We developed a spleen colony assay for the clonogenic component of the tumor and used it to define the dose-response relationships for various anticancer agents, including melphalan, cyclophosphamide, 1,3-bis(chloroethyl)-1-nitrosourea, 5-fluouracil, gamma-radiation, methotrexate, methylprednisolone, cytosine arabinoside, and vincristine.

Animals↗

PubMed1984

Amphotericin B potentiation of the cytotoxicity of anticancer agents against both normal hematopoietic and leukemia cells in mice.

Dose-response curves in AKR or CD2F1 mice were obtained for AKR leukemia, L1210 leukemia, and hematopoietic stem cells following in vivo administration of one of the following anticancer agents alone or in combination with amphotericin B (AmB): doxorubicin, lomustine, or melphalan. AmB potentiated drug cytotoxicity of all agents against both leukemias. Potentiation of all three agents was greatest with the AKR leukemia demonstrating dose-modifying factor (DMF) values of 1.8, 3.0, and 2.7, respectively, for lomustine, melphalan, and doxorubicin. L1210 leukemia was somewhat less sensitive to drug potentiation by AmB with respective DMF values of 1.8, 1.8, and 1.3. AmB did not potentiate the action of any agent against hematopoietic stem cells. The increased life-span assays generally confirmed the clonogenic assays supporting the validity of the latter results. The specificity of AmB potentiation of anticancer agent cytotoxicity for tumor cells indicates that AmB may be a useful addition to antitumor drug combinations.

Amphotericin B↗

PubMed1988

Predictive model for plasma concentration-versus-time profiles of investigational anticancer drugs in patients.

We report a model that provides a strong correlation between mouse toxicity data [mouse lethal dose 10% (LD10)] and human plasma concentration-versus-time (CXT) data for 22 commonly used anticancer agents. Mouse toxicity data (LD10) from two dosing schedules, daily times one and daily times seven, were evaluated for the two mouse strains BDF/1 and Swiss. Data from BDF/1 mice were selected for analysis because they were more abundant. Strong correlations were found between LD10 and human plasma CXT data for both daily times one and daily times seven dosing schedules--ln (CXT) = -1.6504 + [0.8408 X ln (LD10)], r = .84, P less than .0001, and ln (CXT) = -0.0754 + [0.8954 X ln (LD10)], r = .90, P less than .0001, respectively. These correlations may serve as useful models to predict the maximally tolerated dose of an investigational anticancer agent prior to entry into clinical trials and to assist in the selection of clinically relevant in vitro CXTs for new-agent screening against human tumors.

Animals↗

PubMed1989

Therapeutic index: a vital component in selection of anticancer agents for clinical trial.

In an attempt to identify anticancer agents more active in the major groups of solid cancers, the National Cancer Institute has replaced the primary murine tumor systems with an in vitro system using human cancer cell lines. A broader approach is being followed in Europe, where considerable reliance will still be placed on data from animal tumor systems. We argue the case for broader preclinical evaluation using animal model systems that are resistant to standard anticancer agents and thus reflect the clinical disease. Selection of compounds for clinical trials should be based on a therapeutic index that will give a more realistic representation of the margin between antitumor activity and toxicity to normal cells. Furthermore, preclinical evaluation can establish understanding of the factors responsible for treatment efficacy, including pharmacokinetics, metabolism, and drug bioavailability.

Animals↗

PubMed1992

Justification for evaluating new anticancer drugs in selected untreated patients with extensive-stage small-cell lung cancer: an Eastern Cooperative Oncology Group randomized study.

BACKGROUND: Studies have shown that response to a given chemotherapy in previously untreated patients with extensive-stage small-cell lung cancer is superior to that in patients previously treated with other regimens. This finding raises the question of whether it is necessary and ethical to study the effects of new anticancer agents in untreated patients. Such studies appear to be the best test for drug development, but there has been no evaluation of whether survival of untreated patients, whose cancer is sensitive to established drugs, is adversely affected in trials of new drugs. PURPOSE: This randomized study of untreated patients with extensive-stage small-cell lung cancer was designed (a) to compare the survival of patients treated with either effective standard chemotherapy or an investigational anticancer drug as initial therapy and (b) to evaluate response rates and toxic effects of such therapies. METHODS: Eighty-six patients were randomly assigned to receive, as initial therapy, either the standard CAV regimen--cyclophosphamide (1000 mg/m2), doxorubicin (50 mg/m2), and vincristine (1.4 mg/m2) every 3 weeks--or the phase II drug menogaril (200 mg/m2) every 4 weeks. Treatment after induction therapy varied, depending on patient response, but nonresponders and those with disease progression received salvage chemotherapy--etoposide (120 mg/m2 on days 1, 2, and 3) and cisplatin (60 mg/m2 on day 1), repeated every 3 weeks. RESULTS: Of the 43 patients on CAV, 42% responded (eight complete responses and 10 partial responses); 5% of the 43 on menogaril responded (two partial responses) (P = .0001). Twelve (22%) of 54 patients responded to salvage chemotherapy (five complete responses and seven partial responses). Within 3 months from start of treatment, twelve patients died--3 patients in the CAV group and nine patients in the menogaril group (P = .12). The estimated median survival was 37 weeks with menogaril and 45 weeks with CAV (P = .28). At 6 months, survival was 76.7% for the CAV group and 67.4% for the menogaril group. At 12 months, survival rates were 24.4% and 27.9%, respectively. Confidence intervals (95%) for the differences between the proportions surviving in the two groups were -9%-28% at 6 months and -25%-14% at 12 months. Use of CAV resulted in significantly higher occurrence of severe and life-threatening treatment-related complications (P = .002). CONCLUSION: The confidence intervals for the differences in survival are too wide to conclude that evaluation of a new drug in untreated patients with extensive-stage small-cell lung cancer is or is not harmful. The data do suggest, however, that use of this study design may have no adverse effect on survival.

Antineoplastic Agents↗

PubMed1994

Evaluation of creatine analogues as a new class of anticancer agents using freshly explanted human tumor cells.

BACKGROUND: The creatine kinase (CK) isozymes and their substrates, creatine and creatine phosphate, are believed to play a pivotal role in energy transduction in tissues with large, fluctuating energy demands, such as skeletal muscle, heart, and brain. This enzyme system may also be involved in the process of cellular transformation. Inhibition of tumor cell growth by creatine analogues has been observed and may be due to the ability of these analogues to impair cellular energy generation and utilization. PURPOSE: An in vitro human tumor colony-forming assay was used to predict the clinical usefulness of creatine analogues as anticancer agents. METHODS: The ability of cyclocreatine (1-carboxymethyl-2-iminoimidazolidine) and homocyclocreatine (1-carboxyethyl-2-iminoimidazolidine) to inhibit the growth of cells prepared from tumor samples taken directly from patients was evaluated by quantitative measurement of colony formation in a soft-agar cell culture assay system. Cyclocreatine was tested in this human tumor colony-forming assay at concentrations ranging from 0.067 to 20 mM against 128 tumor samples, 51 of which formed colonies in the assay and were considered evaluable. Homocyclocreatine was similarly tested at concentrations from 0.2 to 20 mM against 139 tumor samples; 54 were considered evaluable. The colony-forming assay was also used to compare the efficacy of the creatine analogues to representatives from the six major classes of standard chemotherapeutics (alkylating agents, antimetabolites, DNA intercalators, platinum compounds, topoisomerase inhibitors, and tubulin-interacting agents). In addition, CK levels were measured in 192 tumor samples that were taken from 166 patients. RESULTS: Cyclocreatine and homocyclocreatine, at concentrations previously achieved in animal tissues (7-20 mM), had antitumor activity against 19% and 50%, respectively, of tumor samples that formed colonies in the assay. Cyclocreatine was effective against a subset of tumors sensitive to homocyclocreatine (P = .023; Fisher's exact test), which was the more potent creatine analogue in this assay (P < .001; McNemar's test). No relationships were seen between tumor samples sensitive to the creatine analogues and those sensitive to standard chemotherapeutics. Pairwise Wilcoxon rank sum tests indicated that CK activity was significantly higher in tumors with any growth in the colony assay compared with tumors that did not grow (P < .025). CONCLUSIONS: The creatine analogues, cyclocreatine and homocyclocreatine, effectively reduced colony formation of freshly explanted human tumor cells. The mechanism of action or resistance to these compounds seems to differ from those of standard chemotherapeutics. IMPLICATIONS: Creatine analogues that may alter the energy status of the tumor cell potentially represent promising new anticancer agents that function through a unique mechanism.

Antineoplastic Agents↗

PubMed1997

Enhancing efficacy of recombinant anticancer vaccines with prime/boost regimens that use two different vectors.

BACKGROUND: The identification of tumor-associated antigens and the cloning of DNA sequences encoding them have enabled the development of anticancer vaccines. Such vaccines target tumors by stimulating an immune response against the antigens. One method of vaccination involves the delivery of antigen-encoding DNA sequences, and a number of recombinant vectors have been used for this purpose. To optimize the efficacy of recombinant vaccines, we compared primary and booster treatment regimens that used a single vector (i.e., homologous boosting) with regimens that used two different vectors (i.e., heterologous boosting). METHODS: Pulmonary tumors (experimental metastases) were induced in BALB/c mice inoculated with CT26.CL25 murine colon carcinoma cells, which express recombinant bacterial beta-galactosidase (the model antigen). Protocols for subsequent vaccination used three vectors that encoded beta-galactosidase--vaccinia (cowpox) virus, fowlpox virus, naked bacterial plasmid DNA. Mouse survival was evaluated in conjunction with antibody and cytotoxic T-lymphocyte responses to beta-galactosidase. RESULTS: Heterologous boosting resulted in significantly longer mouse survival than homologous boosting (all P<.0001, two-sided). Potent antigen-specific cytotoxic T lymphocytes were generated following heterologous boosting with poxvirus vectors. This response was not observed with any of the homologous boosting regimens. Mice primed with recombinant poxvirus vectors generated highly specific antibodies against viral proteins. CONCLUSIONS: The poor efficacy of homologous boosting regimens with viral vectors was probably a consequence of the induction of a strong antiviral antibody response. Heterologous boosting augmented antitumor immunity by generating a strong antigen-specific cytotoxic T-lymphocyte response. These data suggest that heterologous boosting strategies may be useful in increasing the efficacy of recombinant DNA anticancer vaccines that have now entered clinical trials.

Animals↗

PubMed2005

OSW-1: a natural compound with potent anticancer activity and a novel mechanism of action.

The naturally occurring compound 3beta,16beta,17alpha-trihydroxycholest-5-en-22-one 16-O-(2-O-4-methoxybenzoyl-beta-D-xylopyranosyl)-(1-->3)-(2-O-acetyl-alpha-L-arabinopyranoside) (OSW-1) is found in the bulbs of Ornithogalum saudersiae and is highly cytotoxic against tumor cell lines. Using various human cancer and nonmalignant cell lines, we investigated the anticancer activity and selectivity of OSW-1 and its underlying mechanisms of action. OSW-1 exhibited extremely potent cytotoxic activity against cancer cells in vitro. Nonmalignant cells were statistically significantly less sensitive to OSW-1 than cancer cells, with concentrations that cause a 50% loss of cell viability 40-150-fold greater than those observed in malignant cells. Electron microscopy and biochemical analyses revealed that OSW-1 damaged the mitochondrial membrane and cristae in both human leukemia and pancreatic cancer cells, leading to the loss of transmembrane potential, increase of cytosolic calcium, and activation of calcium-dependent apoptosis. Clones of leukemia cells with mitochondrial DNA defects and respiration deficiency that had adapted the ability to survive in culture without mitochondrial respiration also were resistant to OSW-1. In vitro analysis revealed that OSW-1 effectively killed primary leukemia cells from chronic lymphocytic leukemia patients with disease refractory to fludarabine. The promising anticancer activity of OSW-1 and its unique mechanism of action make this compound worthy of further investigation for its potential to overcome drug resistance.

Antineoplastic Agents↗