alvocidib and Neoplasms

Flavopiridol is a flavone synthesized from the natural product rohitukine, which is derived from an Indian medicinal plant, namely

Topics: Antineoplastic Agents; Apoptosis; Cyclin-Dependent Kinases; Flavonoids; Humans; Neoplasms; Phosphorylation

Cyclin-dependent kinase 9 (CDK9), which regulates transcriptional elongation, is an attractive therapeutic target for many cancers, especially for cancers driven by transcriptional dysregulation. In particular, CDK9 promotes RNA polymerase II pause/release, a rate-limiting step in normal transcriptional regulation that is frequently dysregulated in cancers. Emerging evidence indicates that selective CDK9 inhibition or degradation may provide a therapeutic benefit against certain cancers. Indeed, the development of CDK9 modulators (inhibitors and degraders) has attracted great attention, with several molecules currently under clinical development. This review provides an overview of recent advances in CDK9 modulators in general, with special emphasis on compounds under clinical evaluation and new emerging strategies, such as proteolysis targeting chimeras (PROTACs).

Topics: Animals; Antineoplastic Agents; Chemistry, Pharmaceutical; Cyclin-Dependent Kinase 9; Drug Development; Humans; Molecular Docking Simulation; Neoplasms; Protein Kinase Inhibitors; Protein Structure, Secondary

Flavonoids have been proposed as potential chemotherapeutic agents because they are toxic against cancer cells but not harmful to healthy cells. This systematic review analyzed flavonoid effectiveness in human cancer chemotherapy. Overall, 22 phase II and 1 phase III clinical trials (PubMed, Scopus, and Web of Science) that used flavonoids as a single agent or combined with other therapeutics against hematopoietic/lymphoid or solid cancer published by January 2019 were selected for analysis. Flavopiridol was the most commonly used flavonoid (at a dose of 50-mg/m

Topics: Antineoplastic Agents; Clinical Trials as Topic; Flavonoids; Humans; Neoplasms; Piperidines; Polyphenols

Protein kinases have been important targets for antitumor targets due to their key roles in regulating multiple cell signaling pathways. Numerous compounds containing flavonoid scaffold as an indispensable anchor have been found to be potent inhibitors of protein kinases. Some of these flavonoids have been in clinical research as protein kinases inhibitors. Thus, the present review mainly focuses on the structural requirement for anticancer potential of flavone derivatives targeting several key serine/threonine protein kinases. This information may provide an opportunity to scientists of medicinal chemistry to design multi-functional flavone derivatives for the treatment of cancer.

Topics: Animals; Antineoplastic Agents; Flavones; Humans; Neoplasms; Protein Binding; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases

There are around 20 Cyclin-dependent kinases (CDKs) known till date, and various research groups have reported their role in different types of cancer. The X-ray structures of some CDKs especially CDK2 was exploited in the past few years, and several inhibitors have been found, e.g., flavopiridol, indirubicin, roscovitine, etc., but due to the specificity issues of these inhibitors (binding to all CDKs), these were called as pan inhibitors. The revolutionary outcome of palbociclib in 2015 as CDK4/6 inhibitor added a new charm to the specific inhibitor design for CDKs. Computer-aided drug design (CADD) tools added a benefit to the design and development of new CDK inhibitors by studying the binding pattern of the inhibitors to the ATP binding domain of CDKs. Herein, we have attempted a comparative analysis of structural differences between several CDKs ATP binding sites and their inhibitor specificity by depicting the important ligand-receptor interactions for a particular CDK to be targeted. This perspective provides futuristic implications in the design of inhibitors considering the spatial features and structural insights of the specific CDK.

Topics: Amino Acid Sequence; Animals; Computer-Aided Design; Crystallography, X-Ray; Cyclin-Dependent Kinases; Drug Design; Humans; Models, Molecular; Neoplasms; Protein Conformation; Protein Kinase Inhibitors; Sequence Alignment

CDK9 is a protein in constant development in cancer therapy. Herein we present an overview of the enzyme as a target for cancer therapy. We provide data on its characteristics and mechanism of action. In recent years, CDK9 inhibitors that have been designed with molecular modeling have demonstrated good antitumoral activity in vitro. Clinical studies of the drugs flavopiridol, dinaciclib, seliciclib, SNS-032 and RGB-286638 used as CDK9 inhibitors are also reviewed, with their additional targets and their relative IC50 values. Unfortunately, treatment with these drugs remains unsuccessful and involves many adverse effects. We could conclude that there are many small molecules that bind to CDK9, but their lack of selectivity against other CDKs do not allow them to get to the clinical use. However, drug designers currently have the tools needed to improve the selectivity of CDK9 inhibitors and to make successful treatment available to patients.

Topics: Bridged Bicyclo Compounds, Heterocyclic; Cell Cycle; Cyclic N-Oxides; Cyclin-Dependent Kinase 9; Flavonoids; Humans; Indolizines; Molecular Targeted Therapy; Neoplasms; Oxazoles; Piperidines; Protein Kinase Inhibitors; Purines; Pyrazoles; Pyridinium Compounds; Roscovitine; Thiazoles; Urea

Emerging evidence demonstrates that the high mobility group A1 (HMGA1) chromatin remodeling protein is a key molecular switch required by cancer cells for tumor progression and a poorly differentiated, stem-like state. Because the HMGA1 gene and proteins are expressed at high levels in all aggressive tumors studied to date, research is needed to determine how to 'turn off' this master regulatory switch in cancer.. In this review, we describe prior studies that underscore the central role of HMGA1 in refractory cancers and we discuss approaches to target HMGA1 in cancer therapy.. Given the widespread overexpression of HMGA1 in diverse, aggressive tumors, further research to develop technology to target HMGA1 holds immense promise as potent anticancer therapy. Previous work in preclinical models indicates that delivery of short hairpin RNA or interfering RNA molecules to 'switch off' HMGA1 expression dramatically impairs cancer cell growth and tumor progression. The advent of nanoparticle technology to systemically deliver DNA or RNA molecules to tumors brings this approach even closer to clinical applications, although further efforts are needed to translate these advances into therapies for cancer patients.

Topics: Animals; Antibiotics, Antineoplastic; Antineoplastic Agents; Cell Differentiation; Chromatin; Clinical Trials as Topic; Cyclooxygenase 2 Inhibitors; Disease Progression; Drug Screening Assays, Antitumor; Flavonoids; Gene Expression Regulation, Neoplastic; Genetic Therapy; HMGA1a Protein; HMGA1b Protein; Humans; Mice; Molecular Targeted Therapy; Nanoparticles; Neoplasm Invasiveness; Neoplasm Proteins; Neoplasms; Oxazines; Piperidines; RNA, Small Interfering; Stem Cells

Natural products are an abundant source of anti cancer agents. They act as cytotoxic drugs, and inhibitors of apoptosis, transcription, cell proliferation and angiogenesis. While pathways targeted by natural products have been well studied, there is paucity of information about the in vivo molecular target/s of these compounds. This review summarizes some of the natural compounds for which the molecular targets, mechanism of action and structural basis of specificity have been well documented. These examples illustrate that 'off target' binding can be explained on the basis of diversity inherent to biomolecular interactions. There is enough evidence to suggest that natural compounds are potent and versatile warheads that can be optimized for a multi targeted therapeutic intervention in cancer.

Topics: Antineoplastic Agents; Benzamides; Biological Products; Cyclohexanes; Epoxy Compounds; Fatty Acids, Unsaturated; Flavonoids; Humans; Imatinib Mesylate; Macrolides; Neoplasms; Piperazines; Piperidines; Proteins; Pyrimidines; Sesquiterpenes

The cell cycle is the series of events necessary for the division and duplication of a cell. The dysregulation of the cell cycle can promote the development of cancer. A group of proteins, cyclin-dependent kinases (CDKs), that control the cell cycle, provide new targets for treating cancer. As a result, cyclin-dependent kinase inhibitors (CDKIs) represent a novel class of chemotherapeutic agents. Of these, flavopiridol, a semisynthetic flavonoidal alkaloid, emerged as the first CDKI to enter clinical trials. Preclinical data indicate that flavopiridol could block the proliferation of neoplastic cells and induce programmed cell death as a single agent. Furthermore, recent emerging data revealed that flavopiridol can potentiate, generally in a dose- and sequence-dependent manner, the anti-tumor effects of many established chemotherapeutic agents. This review is primarily focused on the role of flavopiridol in combination with various therapeutic agents that are in or near clinical development.

Topics: Antineoplastic Agents; Cell Proliferation; Clinical Trials, Phase I as Topic; Cyclin-Dependent Kinases; Drug Design; Drug Synergism; Drug Therapy, Combination; Flavonoids; Humans; Neoplasms; Piperidines

Topics: Animals; Antineoplastic Agents; Cell Cycle; Cyclin-Dependent Kinases; Cyclins; Flavonoids; Humans; Neoplasms; Piperidines; Purines; Roscovitine; Staurosporine

The inhibition of cyclin-dependent kinases (CDKs) represents a novel approach to the therapy of human malignancies. Already in clinical trials, recently developed CDK inhibitors very efficiently target the rapidly proliferating cancer cells and inhibit their cell-cycle progression. Interestingly, some CDK inhibitors additionally affect the stability and activity of the tumour-suppressor protein p53, thereby enhancing their antiproliferative action towards cancer cells. Considering the fact that the p53 protein is mutated or inactivated in approximately 50% of all human cancers, the efficacy of CDK inhibitor therapy could differ between cancer cells depending on their p53 status. Moreover, recent reports demonstrating that some cancer cells can proliferate despite CDK2 inhibition questioned the central role of CDK2 in the cell-cycle control and suitability of CDK2 as a therapeutic target; however, the p53 activation that is mediated by CDK inhibitors could be essential for the efficacy of CDK inhibitors in therapy of CDK2-independent cancers. Furthermore, there is also reason to believe that CDK2 inhibitors could be used for another purpose, to protect normal cells from the effects of chemotherapy.

Topics: Animals; Antineoplastic Agents; Cell Cycle; Cell Proliferation; Clinical Trials as Topic; Cyclin-Dependent Kinase Inhibitor Proteins; Cyclin-Dependent Kinases; Drug Evaluation, Preclinical; Flavonoids; Gene Expression Regulation; Humans; Mutation; Neoplasms; Piperidines; Protein Kinase Inhibitors; Purines; Roscovitine; Transcription, Genetic; Tumor Suppressor Protein p53

Cell cycle kinases are comprised of cyclin-dependent kinases (Cdks), non-Cdk kinases such as Plk-1 and Aurora and checkpoint proteins such as Chk1 and Chk2. Though ubiquitous to dividing cells, many cell cycle kinases are amplified or over-expressed in malignancy and are potential targets for anti-cancer therapies. Cdk inhibiting drugs (such as flavopiridol, UCN-01, E7070, R-Roscovitine and BMS-387032) have shown preclinical and clinical anticancer activity. However, many of these agents are promiscuous and undiscerning, targeting other non-cell cycle kinases and affecting normal cells, thereby causing significant toxicity. To overcome this, a new generation of Cdk inhibitors are in development with greater target specificity, as well as others that inhibit non-Cdk cell cycle kinases, both directly and indirectly. The outcome of early clinical trials involving these agents is awaited, but these certainly represent a promising new area of anticancer drug development.

Topics: Adenosine Triphosphate; Animals; Antineoplastic Agents; Binding Sites; Cyclin-Dependent Kinases; Flavonoids; Humans; Neoplasms; Oxazoles; Piperidines; Protein Kinase Inhibitors; Purines; Roscovitine; Staurosporine; Sulfonamides; Thiazoles

Topics: Animals; Antineoplastic Agents; Cyclin-Dependent Kinases; Flavonoids; Humans; Neoplasms; Piperidines

Most human malignancies have an aberration in the Rb pathway due to 'cdk hyperactivation'. Several small-molecule cdk modulators are being discovered and tested in the clinic. The first ATP-competitive cdk inhibitors tested in clinical trials, flavopiridol and UCN-01, have shown promising results with evidence of antitumor activity and plasma concentrations sufficient to inhibit cdk-related functions. The best schedule to be administered, combination with standard chemotherapeutic agents, best tumor types to be targeted, and demonstration of cdk modulation from tumor samples from patients in these trials are important issues that need to be answered to advance these agents to the clinical arena.

Topics: Animals; Antineoplastic Agents; Cell Cycle; Clinical Trials as Topic; Cyclin-Dependent Kinases; Flavonoids; Humans; Neoplasms; Piperidines; Protein Kinase Inhibitors; Staurosporine

Three closely related forms of glycogen synthase kinase 3 (GSK-3alpha, GSK-3beta and GSK-3beta2) have a major role in Wnt and Hedgehog signaling pathways and regulate the cell-division cycle, stem-cell renewal and differentiation, apoptosis, circadian rhythm, transcription and insulin action. A large body of evidence supports speculation that pharmacological inhibitors of GSK-3 could be used to treat several diseases, including Alzheimer's disease and other neurodegenerative diseases, bipolar affective disorder, diabetes, and diseases caused by unicellular parasites that express GSK-3 homologues. The toxicity, associated side-effects and concerns regarding the absorption, distribution, metabolism and excretion of these inhibitors affect their clinical potential. More than 30 inhibitors of GSK-3 have been identified. Seven of these have been co-crystallized with GSK-3beta and all localize within the ATP-binding pocket of the enzyme. GSK-3, as part of a multi-protein complex that contains proteins such as axin, presenilin and beta-catenin, contains many additional target sites for specific modulation of its activity.

Topics: Animals; Cell Differentiation; Diabetes Mellitus, Type 2; Enzyme Inhibitors; Glycogen Synthase Kinase 3; Humans; Neoplasms; Nervous System Diseases; Parasitic Diseases; Signal Transduction; Stem Cells; Structure-Activity Relationship

Eukaryotic organisms depend on an intricate and evolutionary conserved cell cycle to control cell division. The cell cycle is regulated by a number of important protein families which are common targets for mutational inactivation or overexpression in human tumours. The cyclin D and E families and their cyclin-dependent kinase partners initiate the phosphorylation of the retinoblastoma tumour suppressor protein and subsequent transition through the cell cycle. Cyclin/cdk activity and therefore control of cell division is restrained by two families of cyclin dependent kinase inhibitors. A greater understanding of the cell cycle has led to the development of a number of compounds with the potential to restore control of cell division in human cancers. This review will introduce the protein families that regulate the cell cycle, their aberrations in malignant progression and pharmacological strategies targeting this important process.

Topics: Animals; Cell Cycle; Clinical Trials as Topic; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Enzyme Inhibitors; Flavonoids; Humans; Neoplasms; Piperidines; Staurosporine

Flavopiridol has potent anti-proliferative properties due to its direct action of binding to the ATP-binding pocket of cyclin-dependent kinases (cdks), and due to its indirect action reducing levels of other cyclins and cdk inhibitors, contributing to its pleiotropic effects. Flavopiridol is a potent apoptotic agent due to its ability to cause cell death in cycling as well as non-cycling tumor cells; to down-regulate important cell survival proteins, such as survivin, through inhibition of the phosphorylation of Thr34; to increase sensitivity for S phase cells to drug treatment by modulating E2F-1 transcription factor activity in tumor cells; to induce both caspase-dependent and -independent mitochondrial cell death pathways; and to inhibit the activation of p-Akt which in turn inhibits activation of NF-kappaB. Flavopiridol possesses several important anti-angiogenic activities including induction of apoptosis of endothelial cells; inhibition of the hypoxic induction of vascular endothelial growth factor and/or its production under hypoxic conditions through inhibition of HIF-1alpha transcription; and decreased secretion of matrix metalloproteinases that is linked with significant inhibition of invasive potential in Matrigel assays. Taken together, the anti-proliferative and anti-angiogenic properties of flavopiridol may contribute to its anti-tumor activities observed in several preclinical animal models of human cancers including prostate, lymphoid, head and neck, colon, and glioma. These promising preclinical observations opened the way for phase I and II clinical trials. Given the low toxicity profile of flavopiridol used as a single agent in patients, combination therapy now offers numerous opportunities in the near future to improve the efficacy of flavopiridol in the treatment of refractory cancers.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Agents; Apoptosis; Clinical Trials as Topic; Flavonoids; Humans; Neoplasms; Piperidines

Flavopiridol is the first potent inhibitor of cyclin-dependent kinases (cdks) to reach clinical trial. In the majority of solid tumor cell lines and xenografts, flavopiridol induces cell cycle arrest and tumor growth inhibition. This is reflected in clinical outcomes: across multiple Phase II trials there are subsets of patients with prolonged stable disease, although few responses have been observed. Flavopiridol displays sequence-dependent cytotoxic synergy with chemotherapy agents. These effects are most marked when chemotherapy precedes flavopiridol. In the case of DNA-damaging agents that impose S-phase delay, flavopiridol-mediated cdk inhibition disrupts the phosphorylation of E2F-1, leading to inappropriate persistence of its activity, inducing apoptotic pathways. This mechanism has been exploited in a Phase I trial of sequential gemcitabine and flavopiridol that has produced promising results. Flavopiridol is also synergistic with taxanes. Inhibition of cyclin B-cdk1 by flavopiridol accelerates exit from an abnormal mitosis associated with taxane-induced cell death and reduces the phosphorylation of survivin, preventing its stabilization and the cellular protection it affords after taxane exposure. The sequential combination of docetaxel and flavopiridol has been investigated in a Phase I trial in patients with advanced non-small cell lung cancer, and a randomized Phase II study is under way. Initial schedules of flavopiridol used prolonged continuous infusions that produced nanomolar levels of drug thought to be capable of achieving cdk inhibition based on results in tumor cell lines. Recently, it has been discovered that micromolar concentrations are likely to be more effective, and shorter infusions that achieve a higher C(max) have now been adopted. Loading followed by maintenance infusions are also under development, designed to achieve sustained micromolar drug levels. Clinical trials remain complicated by the absence of pharmacodynamic end points to confirm target inhibition.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Cycle; Clinical Trials as Topic; Cyclin-Dependent Kinases; Drug Administration Schedule; Flavonoids; Humans; Neoplasms; Piperidines; Tumor Cells, Cultured

Abnormalities in the cell cycle are responsible for the majority of human neoplasias. Most abnormalities occur due to hyperphosphorylation of the tumor suppressor gene Rb by the key regulators of the cell cycle, the cyclin-dependent kinases (CDKs). Thus, a pharmacological CDK inhibitor may be useful in the prevention and/or treatment of human neoplasms. Flavopiridol is a flavonoid with interesting preclinical properties: (1) potent CDK inhibitory activity; (2) it depletes cyclin D1 and vascular endothelial growth factor mRNA by transcriptional and posttranscriptional mechanisms, respectively; (3) it inhibits positive elongation factor B, leading to transcription "halt"; and (4) it induces apoptosis in several preclinical models. The first phase I trial of a CDK inhibitor, flavopiridol, has been completed. Dose-limiting toxicities included secretory diarrhea and proinflammatory syndrome. Antitumor activity was observed in some patients with non-Hodgkin's lymphoma and renal, colon, and prostate cancers. Concentrations between 300 and 500 n M-necessary to inhibit CDK-were achieved safely. Phase II trials with infusional flavopiridol and phase I infusional trials in combination with standard chemotherapy are being completed with encouraging results. A novel phase I trial of 1-h flavopiridol administration was recently completed. The maximum tolerated doses using flavopiridol daily for 5, 3, and 1 consecutive days are 37.5, 50, and 62.5 mg/m(2) per day. Dose-limiting toxicities include vomiting, neutropenia, proinflammatory syndrome, and diarrhea. Plasma flavopiridol concentrations achieved were in the range 1.5-3.5 MICRO M. Phase II/III trials using this 1-h schedule in several tumor types including non-small-cell lung cancer, chronic lymphocytic leukemia, mantle cell lymphoma, and head and neck cancer are being conducted worldwide. UCN-01, the second CDK modulator that has entered clinical trials, has unique preclinical properties: (1) it inhibits protein kinase C (PKC) activity; (2) it promotes cell-cycle arrest by accumulation in p21/p27; (3) it induces apoptosis in several preclinical models; and (4) it abrogates the G(2) checkpoint by inhibition of chk1. The last of these represents a novel strategy to combine UCN-01 with DNA-damaging agents. In the initial UCN-01 clinical trial (continuous infusion for 72 h), a prolonged half-life of about 600 h (100 times longer than in preclinical models) was observed. The maximum tolerated dose was 42.5 mg/m(2) per d

Topics: Alkaloids; Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Cycle; Clinical Trials as Topic; Cyclin-Dependent Kinases; Enzyme Inhibitors; Flavonoids; Humans; Neoplasms; Piperidines; Staurosporine; Tumor Cells, Cultured

Cell-cycle dysregulation is one of the cardinal characteristics of neoplastic cells. For this reason, small molecule inhibitors targeting cyclin-dependent kinases (CDKs), of which flavopiridol is a prototype, have been the focus of extensive interest in cancer therapy. In addition to inhibiting cell-cycle progression, these agents exhibit a variety of other activities, including the induction of cell death. Recently, several novel mechanisms of action have been ascribed to the CDK inhibitor flavopiridol, including interference with transcription, most likely through disruption of P-TEFb (i.e. the CDK9/cyclin T complex), and induction of apoptosis, possibly a consequence of downregulation of various anti-apoptotic proteins. It has also been observed that combining CDK inhibitors with either conventional cytotoxic drugs or novel signal transduction modulators dramatically promotes neoplastic cell death in a variety of preclinical models. Efforts are underway to uncover inhibitors that selectively target specific CDKs and to develop these as a new generation of antitumour drugs. For all of these reasons, it is likely that interest in CDK inhibitors as antineoplastic agents will continue for the foreseeable future.

Topics: Animals; Antineoplastic Agents; Apoptosis; Clinical Trials as Topic; Cyclin-Dependent Kinases; Drug Resistance, Neoplasm; Drug Synergism; Flavonoids; Humans; Neoplasms; Piperidines; Transcription, Genetic

Many tumor types are associated with genetic changes in the retinoblastoma pathway, leading to hyperactivation of cyclin-dependent kinases and incorrect progression through the cell cycle. Small-molecule cyclin-dependent kinase inhibitors are being developed as therapeutic agents. Of these, flavopiridol and UCN-01 are being explored in cancer patients in phase I and phase II clinical trials, both as single agents and in combination with conventional chemotherapeutic agents. The present article discusses the mechanisms of action of flavopiridol and UCN-01 as well as the outcome of clinical trials with these novel agents.

Topics: Alkaloids; Animals; Antineoplastic Agents; Cell Cycle; Clinical Trials as Topic; Cyclin-Dependent Kinases; Enzyme Inhibitors; Flavonoids; Humans; Neoplasms; Piperidines; Staurosporine

Based on the frequent aberration in cell cycle regulatory pathways in human cancer by cdk hyperactivation, novel ATP competitive cdk inhibitors are being developed. The first two tested in clinical trials, flavopiridol and UCN-01, showed promising results with evidence of antitumor activity and plasma concentrations sufficient to inhibit cdk-related functions. Best schedule to be administered, combination with standard chemotherapeutic agents, best tumor types to be targeted, and demonstration of cdk modulation from tumor samples from patients in these trials are important questions that need to be answered to advance these agents to the clinic.

Topics: Alkaloids; Antineoplastic Agents; Apoptosis; Cell Cycle; Cell Differentiation; Clinical Trials, Phase I as Topic; Cyclin-Dependent Kinases; Drug Design; Drug Screening Assays, Antitumor; Enzyme Inhibitors; Flavonoids; Humans; Neoplasm Proteins; Neoplasms; Piperidines; Signal Transduction; Staurosporine; Transcription, Genetic

To review preclinical and clinical information on flavopiridol, an inhibitor of cyclin-dependent kinases (CDKs), tested as an antitumor agent.. Primary and review articles were identified by MEDLINE search (1990-June 2001). Abstracts from recent meetings were also used as source materials.. Flavopiridol was reviewed with regard to its mechanisms, preclinical and clinical results, pharmacokinetics, and metabolism.. Flavopiridol is an inhibitor of several CDKs and displays unique anticancer properties. In addition to direct CDK inhibition, flavopiridol also exhibited other features such as inducing apoptosis in many cancer cell lines, decreasing cyclin D1 concentration, and inhibiting angiogenesis. Preclinical xenograft models showed significant antitumor activity for flavopiridol. The regimen using 72-hour continuous infusion every 2 weeks has been most extensively applied in clinical trials, with a 1-hour infusion currently being explored to achieve higher peak concentrations. Several Phase I and II trials have been reported, with some evidence of antitumor activity noted. Further Phase I and II trials using flavopiridol as a single agent and in combination with standard chemotherapeutic regimens and various tumor types are ongoing.. Flavopiridol is the first CDK inhibitor to enter clinical trials. Several Phase I and Phase II clinical trials with different regimens (72-h or 1-h infusion) have been completed. Initial clinical trials have been intriguing, but many questions remain: What is the best regimen (< or =72-h infusion)? Does optimal future development of this drug depend on the combination with other chemotherapy? What is the best combination of flavopiridol with other chemotherapy?

Topics: Antineoplastic Agents; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Colonic Neoplasms; Cyclin-Dependent Kinases; Diarrhea; Drug Evaluation, Preclinical; Drug Therapy, Combination; Fatigue; Flavonoids; Humans; Infusion Pumps; Kidney Neoplasms; Lymphoma, Non-Hodgkin; Neoplasms; Neutropenia; Piperidines

Flavopiridol is a synthetic flavonoid inhibitor of cyclin-dependent kinases, which is under development by Aventis Pharma (formerly Hoechst Marion Roussel) and the National Cancer Institute (NCI) for the potential treatment of cancer and proliferative disorders. By May 2001, the product was in phase IIa trials and had achieved proof-of-concept in phase I/IIa trials as a monotherapy. At this time, Aventis expected a global submission to take place in 2003 [409257]. By July 1999, the compound had entered phase II trials for gastric cancer and leukemia, and phase I/II trials for esophageal tumor and non-small cell lung cancer (NSCLC) [277372], [325929], [331850]. Phase II trials for colon and renal cancer [411684], [411769] and phase I trials for prostate cancer [279466] have also been reported. Analysts Merrill Lynch predicted in September and November 2000 that the product would be launched by 2003, with sales of EUR 50 million in that year, rising to EUR 100 million in 2004 [383742], [391426]. In April 1999, ABN Amro predicted annual sales of DM 100 million in 2002 [328676].

Topics: Animals; Antineoplastic Agents; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Flavonoids; Humans; Neoplasms; Piperidines; Structure-Activity Relationship

In the last decade, the discovery and cloning of the cyclin-dependent kinases (cdks), key regulators of cell cycle progression, have led to the identification of novel modulators of cdk activity. Initial experimental results demonstrated that these cdk modulators are able to block cell cycle progression, induce apoptotic cell death, promote differentiation, inhibit angiogenesis, and modulate transcription. Alteration of cdk activity may occur indirectly by affecting upstream pathways that regulate cdk activity or directly by targeting the cdk holoenzyme. Two direct cdk modulators, flavopiridol and UCN-01, are showing promising results in early clinical trials, in which the drugs reach plasma concentrations that can alter cdk activity in vitro. Although modulation of cdk activity is a well-grounded concept and new cdk modulators are being assessed for clinical testing, important scientific questions remain to be addressed. These questions include whether one or more cdks should be inhibited, how cdk inhibitors should be combined with other chemotherapy agents, and which cdk substrates should be used to assess the biologic effects of these drugs in patients. Thus, modulation of cdk activity is an attractive target for cancer chemotherapy, and several agents that modulate cdk activity are in or are approaching entry into clinical trials.

Topics: Alkaloids; Animals; Antineoplastic Agents; Cell Cycle; Clinical Trials as Topic; Cyclin-Dependent Kinases; Enzyme Inhibitors; Flavonoids; Humans; Neoplasms; Piperidines; Staurosporine

Four most widely investigated flavonoids, flavopiridol, catechins, genistein and quercetin are reviewed in this article. Flavopiridol is a novel semisynthetic flavone analogue of rohitukine, a leading anticancer compound from an Indian tree. Flavopiridol inhibits most cyclin-dependent kinases and displays unique anticancer properties. It is the first cyclin-dependent kinase inhibitor to be tested in Phase II clinical trials. Catechin and its gallate are major ingredients in green tea and their anti-oxidant and cancer preventive effects have been widely investigated. A Phase I study of green tea extract GTE-TP91 has been conducted in adult patients with solid tumours. Similarly, genistein is a major ingredient in soybean and has been shown to prevent cancer and have antitumour, anti-oxidant and anti-inflammatory effects. Two antibody-genistein conjugates, B43-genistein and EGF-genistein, are currently in clinical development for the treatment of acute lymphoblastic leukaemia and breast cancer, respectively. Finally, most recent updates of quercetin are briefly described.

Topics: Adult; Animals; Antineoplastic Agents; Catechin; Clinical Trials as Topic; Dietary Supplements; Drug Screening Assays, Antitumor; Flavonoids; Genistein; Humans; Neoplasms; Piperidines; Quercetin

Topics: Antineoplastic Agents; Apoptosis; Cell Division; Clinical Trials as Topic; Cyclin-Dependent Kinases; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Flavonoids; Humans; Neoplasms; Piperidines; Structure-Activity Relationship; Tumor Cells, Cultured

This review focuses on the clinical development of the prototype broad spectrum inhibitor of cyclin-dependent kinases (CDKs), flavopiridol, now undergoing Phase II single-agent trials and Phase I combination trials (with paclitaxel and cisplatin). Preclinically, flavopiridol is a potent inhibitor of CDKs 1, 2 and 4 in cell-free assays (IC(50)in the region of 100 nM) and tumour cell growth in vitro (typical IC(50)in the region of 100 nM). The drug showed in vivo antitumour activity (using iv., ip. or oral dosing) against a variety of human tumour xenografts, especially when administered on a regular daily, rather than weekly, schedule and most notably against prostate carcinoma, head and neck cancer, non-Hodgkin's lymphoma and leukaemia. The major toxicities observed in rodents were on the bone marrow and gastrointestinal tract. Pharmacokinetics were linear with dose and with a bi-exponential decline both in rodents and man. Oral bioavailability in rodents is in the region of 20%. Glucuronidation appears to be the major route of metabolism. Single-agent clinical trials have mainly used a 72 h continuous infusion schedule. Dose-limiting toxicities were diarrhoea and hypotension. Plasma concentrations in excess of those required for in vitro enzyme or cell growth inhibition are achievable. While there has been some evidence of single-agent antitumour activity (partial responses in a patient with renal cancer and another with gastric cancer), ongoing combination studies, especially with paclitaxel, where preclinical synergistic antitumour effects are observed, are promising. Doubt as to whether CDKs are the sole target responsible for the drug's antitumour effects have been raised by preclinical observations of apoptosis of non-cycling cells, effects on endothelial cells and non-CDK proteins, such as aldehyde dehydrogenase and glycogen phosphorylase, potent effects on PTEFb and transcription and its ability to directly interact with DNA.

Topics: Animals; Antineoplastic Agents; Clinical Trials as Topic; Cyclin-Dependent Kinases; Flavonoids; Humans; Neoplasms; Piperidines

The discovery and cloning of the cyclin-dependent kinases (cdks), main regulators of cell cycle progression, allowed several investigators to design novel modulators of cdk activity. Flavopiridol (HMR 1275, L86-8275), a flavonoid derived from an indigenous plant from India, demonstrated potent and specific in vitro inhibition of all cdks tested (cdks 1, 2, 4 and 7) with clear block in cell cycle progression at the G1/S and G2/M boundaries. Moreover, preclinical studies demonstrated the capacity of flavopiridol to induce programmed cell death, promote differentiation, inhibit angiogenic processes and modulate transcriptional events. The relationship between the latter effects and cdk inhibition is still unclear. Initial testing in early clinical human trials with infusional flavopiridol showed activity in some patients with non-Hodgkin's lymphoma, renal, prostate, colon and gastric carcinomas. Main side effects were secretory diarrhea and a pro-inflammatory syndrome associated with hypotension. Biologically active plasma concentrations of flavopiridol (approximately 300-500 nM) are easily achievable in patients receiving infusional flavopiridol. Phase 2 trials with infusional flavopiridol in several tumor types, other schedules and combination with standard chemotherapies are being assessed. In conclusion, flavopiridol is the first cdk inhibitor to be tested in clinical trials. Although important questions remain to be answered, this positive experience will stimulate the development of novel cdk modulators for cancer therapy.

Topics: Antineoplastic Agents; Cell Cycle; Clinical Trials as Topic; Cyclin-Dependent Kinases; Enzyme Inhibitors; Flavonoids; Humans; Neoplasms; Piperidines

Based on the promising activity and tolerability of flavopiridol administered with a pharmacokinetically-derived dosing schedule in chronic lymphocytic leukemia (CLL), we conducted a phase I study using this schedule in patients with advanced solid tumors.. Flavopiridol was given IV as a 30-min loading dose followed by a 4-hr infusion weekly for 4 weeks repeated every 6 weeks. Dose-escalation was in cohorts of three patients using the standard 3+3 phase I study design. Blood samples were obtained for pharmacokinetic and pharmacodynamic studies.. Thirty-four eligible patients with advanced solid tumors received a total of 208 doses (median 7, range 1-24). Total doses ranged from 40 to 105 mg/m(2). The primary dose limiting toxicity was cytokine release syndrome (CKRS). No antitumor responses were observed. The mean peak plasma concentration across all doses was 1.65 ± 0.86 μM. Area under the concentration-versus-time curve ([Formula: see text]) ranged from 4.31 to 32.2 μM[Symbol: see text]hr with an overall mean of 13.6 ± 7.0 μM[Symbol: see text]hr. Plasma flavopiridol concentrations and AUC increased proportionally with dose. There was no correlation between cytokine levels and clinical outcomes.. The maximum-tolerated dose of flavopiridol is 20 mg/m(2) bolus followed by 20 mg/m(2) infusion over 4 h given weekly for 4 weeks on a 6-week cycle in patients with advanced solid tumors. Flavopiridol PK was notably different, and there was a higher frequency of CKRS, despite prophylactic steroids, seen in this patient group compared to previous studies with CLL using a similar dosing schedule.

Topics: Adult; Aged; Antineoplastic Agents; Area Under Curve; Cytokines; Female; Flavonoids; Humans; Infusions, Intravenous; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms; Ohio; Piperidines; Protein Kinase Inhibitors; Treatment Outcome

Vorinostat (V) at levels >2.5 µM enhances chemotherapy in vitro. Yet the approved oral dose of 400 mg inconsistently achieves this level in patients. We developed an intermittent oral pulse-dose schedule of V to increase serum levels. We combined V with the cyclin dependent kinase inhibitor flavopiridol (F) which increases V-induced apoptosis.. One week before combination treatment, V alone was given daily for 3d (cycle -1). Then V was given on d1-3 and d8-10, and F on d2 and d9, every 21-d. Due to neutropenia, this was modified to V on d1-3 and d15-17, and F on d2 and d16, every 28-d. Bolus and split-dose F schedules were studied.. 34 patients were treated. On the 21-d schedule, the maximum tolerated dose (MTD) was V 600 mg/d and F 60 mg/m(2) bolus. On the 28-d schedule, the MTD was V 800 mg/d and F 30 mg/m(2) over 30 min and 30 mg/m(2) over 4 h. V C(max) at the 800 mg dose was 4.8 µM (± 2.8). V C(max) ≥ 2.5 µM was achieved in 86% of patients at the MTD. F increased the C(max) of V by 27% (95% CI 11%-43%). F C(max) of ≥ 2 µM was achieved in 90% of patients. 8 patients had stable disease for on average 5.5 m (range 1.6-13.2 m).. Intermittent high dose oral V in combination with F is feasible and achieves target serum levels >2.5 µM. V concentrations higher than previously reported with oral dosing were achieved.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Cohort Studies; Dose-Response Relationship, Drug; Female; Flavonoids; Humans; Hydroxamic Acids; Male; Middle Aged; Neoplasms; Piperidines; Vorinostat

The cyclin-dependent kinase inhibitor flavopiridol increases irinotecan- and fluorouracil-induced apoptosis. We conducted a phase I trial of FOLFIRI + flavopiridol in patients with advanced solid tumors.. FOLFIRI + flavopiridol were administered every 2 weeks. Based on sequence-dependent inhibition, flavopiridol was given 3 h after irinotecan but before 5-FU. Two maximum tolerated doses were determined, one with flavopiridol administered over 1 h, and one with flavopiridol split as a 30-min bolus followed by a 4-h infusion.. A total of 74 patients were enrolled and 63 were evaluable. The MTD with FOLFIRI was flavopiridol 80 mg/m(2) over 1 h or 35 mg/m(2) bolus + 35 mg/m(2) over 4 h. Dose-limiting toxicities were diarrhea, fatigue, neutropenia, and neuropathy. Clinical activity included 2 partial responses in small bowel cancer and bladder cancer and 1 complete response in mucosal melanoma. Stable disease was seen in 22 patients. Pharmacokinetic studies showed increasing C(max) with increasing flavopiridol dose. Clinical benefit was correlated with the presence of wild-type p53. Of 25 patients with colorectal cancer, 11 had as best response SD for >3 m (median 6 m, range 4.2-15.4 m), despite failing ≥1 irinotecan-containing regimen.. Treatment with flavopiridol and FOLFIRI is a safe and effective regimen. Concentrations of flavopiridol that enhance the effects of FOLFIRI can be achieved. Clinical activity is encouraging and includes prolonged stable disease in patients with irinotecan-refractory colorectal cancer.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Camptothecin; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Flavonoids; Fluorouracil; Humans; Infusions, Intravenous; Injections, Intravenous; Irinotecan; Leucovorin; Male; Middle Aged; Neoplasms; Piperidines; Protein Kinase Inhibitors; Treatment Outcome

Flavopiridol, a cyclin-dependent kinase inhibitor, has promising clinical activity when combined with chemotherapy. Preclinical data indicate that flavopiridol enhances oxaliplatin- and fluorouracil (5FU)-induced apoptosis in a sequence-dependent manner.. We conducted a phase I trial of flavopiridol + FOLFOX (folinic acid, 5FU, and oxaliplatin) for advanced solid tumors. Flavopiridol was administered every 2 weeks with oxaliplatin before 5FU, based on sequence-dependent growth inhibition. Flavopiridol pharmacokinetics and p53 status were evaluated.. Forty-eight patients were treated on study. With dose escalation of oxaliplatin (85 mg/m(2)) and 5FU (2,400 mg/m(2)), dose-limiting toxicities included hyponatremia, thrombocytopenia, and neutropenia. 5FU was subsequently reduced to allow for dose escalation of flavopiridol. Dose-limiting toxicities with escalation of flavopiridol were nausea, vomiting, and neutropenia. The maximum tolerated dose was 70 mg/m(2) flavopiridol, 85 mg/m(2) oxaliplatin, and 1,800 mg/m(2) 5FU continuous infusion over 48 hours. Clinical activity was noted in platinum-refractory germ cell tumors: 3 of 9 (33%) evaluable patients showed a partial response on imaging and 7 of 10 (70%) had a decline in serum tumor markers. Responses were also observed in pancreatic, gastric, and sweat gland tumors. Flavopiridol pharmacokinetics had significant interpatient variability. At the maximum tolerated dose, tumor samples were p53 mutant (>30% positive cells) for responders and p53 wild-type for nonresponders.. Flavopiridol with FOLFOX is a safe and tolerable regimen. Promising clinical activity was seen across tumor types. Encouraging results in the platinum-refractory germ cell tumor population has prompted a phase II trial that is currently open for accrual.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cyclin-Dependent Kinases; Female; Flavonoids; Fluorouracil; Humans; Leucovorin; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms; Organoplatinum Compounds; Oxaliplatin; Piperidines; Tumor Suppressor Protein p53

Flavopiridol is a cyclin-dependent kinase inhibitor that enhances docetaxel-induced apoptosis in a sequence-specific manner. In vivo, docetaxel must precede flavopiridol by at least 4 h to induce this effect. We conducted a phase I trial of weekly, sequential docetaxel followed 4 h later by flavopiridol in patients with advanced solid tumors.. Docetaxel at a fixed dose of 35 mg/m2 was administered over 30 min, followed 4 h later by escalating doses of flavopiridol, ranging from 20 to 80 mg/m2 in successive cohorts, administered weekly over 1 h. This schedule was repeated for 3 weeks of each 4-week cycle.. Twenty-seven evaluable patients were enrolled. The combination was well tolerated, with one dose-limiting toxicity occurring at flavopiridol 70 mg/m2 (grade 3 mucositis) and one dose-limiting toxicity at 80 mg/m2 (grade 4 neutropenia). We observed 1 complete response in a patient with pancreatic carcinoma and 4 partial responses in pancreatic (1), breast (2), and ovarian (1) cancer patients. Stable disease was seen in 10 patients. Pharmacokinetic studies showed Cmax ranging from 1.49 +/- 0.69 micromol/L (flavopiridol 20 mg/m2) to 4.54 +/- 0.08 micromol/L (flavopiridol 60 mg/m2) in cycle 1.. Treatment with weekly, sequential docetaxel followed by flavopiridol is an effective and safe regimen at all flavopiridol dose levels. The pharmacokinetic data indicate that concentrations of flavopiridol that enhance the effects of docetaxel both in vitro and in vivo can be achieved. Clinical activity is encouraging, even in patients who have received a prior taxane and in patients with gemcitabine-refractory metastatic pancreatic cancer.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Deoxycytidine; Docetaxel; Drug Administration Schedule; Drug Resistance, Neoplasm; Drug Synergism; Female; Flavonoids; Gemcitabine; Humans; Male; Middle Aged; Neoplasms; Piperidines; Taxoids; Treatment Outcome

Flavopiridol potently enhances the effect of irinotecan with cures in colorectal cancer xenografts, and is associated with modulation of several molecular targets, including p21, Differentiation-related gene 1 (Drg1), and p53. We initiated a phase I trial of the sequential combination of irinotecan followed by flavopiridol to determine the maximal tolerated dose of this combination therapy.. Forty-five patients with advanced solid tumors were enrolled. Irinotecan was administered first (100 or 125 mg/m(2)) followed 7 hours later by escalating flavopiridol (10-70 mg/m(2)) given weekly over 1 hour for 4 of 6 weeks. At the maximal tolerated dose, the pharmacokinetic analysis was expanded and pre- and posttreatment tumor biopsies were done.. At irinotecan 100 mg/m(2), dose-limiting diarrhea and myelosuppression were observed with flavopiridol 70 mg/m(2). At irinotecan 125 mg/m(2), we observed dose-limiting hyperbilirubinemia, fatigue, and myelosuppression at flavopiridol 60 mg/m(2). Peak flavopiridol concentrations of >/=2 mumol/L were achieved above flavopiridol 50 mg/m(2). No significant pharmacokinetic interactions with irinotecan were noted. Baseline serum bilirubin significantly predicted cycle 1 dose-limiting toxicity and neutropenia. We observed partial responses in three patients and prolonged stable disease (i.e., >6 months) in 36% of patients including adrenocortical cancer and hepatocellular cancer. Patients with wild-type p53 and either no change or low posttreatment biopsy p21 and a decrease in Drg1 expression showed stable or responsive disease to the combination therapy.. The recommended phase II dose with irinotecan 100 mg/m(2) is flavopiridol 60 mg/m(2) and with irinotecan 125 mg/m(2) is flavopiridol 50 mg/m(2). Toxicity can be predicted by baseline bilirubin. Clinical activity is encouraging and may correlate to changes in p21 and Drg1 levels in patients with wild type p53 tumors following therapy.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Bilirubin; Camptothecin; Cell Cycle Proteins; Cyclin-Dependent Kinase Inhibitor p21; Drug Administration Schedule; Drug Interactions; Female; Flavonoids; Humans; Intracellular Signaling Peptides and Proteins; Irinotecan; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms; Piperidines; Treatment Outcome; Tumor Suppressor Protein p53

Flavopiridol, a cyclin-dependent kinase inhibitor, transcription inhibitor, and DNA-interacting agent, was combined with cisplatin or carboplatin to establish toxicities, evaluate pharmacokinetics, and examine its effects on patient cancers and levels of selected polypeptides in patient peripheral blood mononuclear cells (PBMC).. Therapy was given every 3 weeks. Stage I: cisplatin was fixed at 30 mg/m2 with escalating flavopiridol. Stage II: flavopiridol was fixed at the stage I maximum tolerated dose (MTD) with escalation of cisplatin. Stage III: flavopiridol was fixed at the stage I MTD with escalation of carboplatin.. Thirty-nine patients were treated with 136 cycles of chemotherapy. Neutropenia was seen in only 11% of patients. Grade 3 flavopiridol/CDDP toxicities were nausea (30%), vomiting (19%), diarrhea (15%), dehydration (15%), and neutropenia (10%). Flavopiridol combined with carboplatin resulted in unexpectedly high toxicities and one treatment-related death. Stable disease (>3 months) was seen in 34% of treated patients, but there were no objective responses. The stage II MTD was 60 mg/m2 cisplatin and 100 mg/m2/24 hours flavopiridol. As given, CDDP did not alter flavopiridol pharmacokinetics. Flavopiridol induced increased p53 and pSTAT3 levels in patient PBMCs but had no effects on cyclin D1, phosphoRNA polymerase II, or Mcl-1.. Flavopiridol and cisplatin can be safely combined in the treatment of cancer patients. Unexpected toxicity in flavopiridol/carboplatin-treated patients attenuates enthusiasm for this alternative combination. Analysis of polypeptide levels in patient PBMCs suggests that flavopiridol may be affecting some, but not all, of its known in vitro molecular targets in vivo.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Area Under Curve; Carboplatin; Cell Line, Tumor; Cisplatin; Cohort Studies; Diarrhea; Dose-Response Relationship, Drug; Female; Flavonoids; Humans; Immunoblotting; Leukocytes, Mononuclear; Male; Middle Aged; Nausea; Neoplasms; Piperidines; Proto-Oncogene Proteins c-bcl-2; STAT3 Transcription Factor; Treatment Outcome; Tumor Suppressor Protein p53

To determine the dose-limiting toxicities, maximum-tolerated dose, and pharmacokinetics of the cyclin-dependent kinase inhibitor flavopiridol (NSC 649890) when administered as a 1-hour infusion over 3 consecutive days to children with recurrent or refractory solid tumors.. Flavopiridol was administered as a 1-hour intravenous infusion daily for 3 consecutive days every 21 days, or when hematologic toxicity or any grade 2 or greater nonhematologic toxicity resolved. The starting dose was 37.5 mg/m2/d. Dose escalation was in cohorts of three patients in a standard fashion until dose-limiting toxicity and the maximum-tolerated dose were determined. Flavopiridol levels were measured on days 1, 2, and 3.. Twenty-five children received flavopiridol at doses of 37.5 to 80 mg/m2/day over 3 consecutive days. The maximum-tolerated dose was 62.5 mg/m2/d. The primary dose-limiting toxicities were neutropenia and diarrhea. No antitumor effect was observed in this population. Mean peak plasma concentrations of 3.71 and 9.11 micromol/L were achieved at the end of the 1-hour infusion, following dose escalation from 37.5 mg/m2 to 80 mg/m2, respectively. The median flavopiridol plasma clearance was 8.0 L/h/m2 (range, 2.6 to 17.1 L/h/m2).. The maximum-tolerated dose of flavopiridol in children, and the recommended phase II dose for pediatric studies, was 62.5 mg/m2/day when administered as a 1-hour infusion for 3 consecutive days. Dose-limiting toxicities of neutropenia and diarrhea were similar to those in adult studies.

Topics: Adolescent; Adult; Antineoplastic Agents; Child; Child, Preschool; Diarrhea; Female; Flavonoids; Humans; Infusions, Intravenous; Male; Maximum Tolerated Dose; Neoplasms; Neutropenia; Piperidines

A phase I trial of flavopiridol administered as a 1-h i.v. infusion schedule was explored. Fifty-five patients were treated with flavopiridol at doses ranging from 12 to 78 mg/m2 daily for 5, 3 and 1 day every 3 weeks. Pharmacokinetic and pharmacodynamic analysis was performed together with analysis of a promoter polymorphism of the UGT1A1 gene. Peak concentrations and areas under the time-concentration curve of flavopiridol were linear within the doses studied. Estimated clearance was 13.8+/-4.9 l/h/m2 (mean+/-SD), volume of distribution at steady-state was 64.9+/-43.4 l/m2 and elimination half-life was 5.2+/-4.9 h. Forty-nine of the 55 patients were genotyped for the promoter polymorphism. We found five (10%) homozygous and 11 (22%) heterozygous patients for UGT1A1*28, which alters the reference sequence (TA)6TAA to the variant (TA)7TAA by an extra TA dinucleotide insertion within the TATA box. One patient was heterozygous for the sequence of five TA repeats, (TA)5TAA. The remaining 32 patients did not have the UGT1A1*28 allele (homozygous for the reference sequence). Associations of the UGT1A1 promoter genotype with either the pharmacokinetic parameters or diarrhea (occurrence and severity) were not observed in this study. The pharmacogenetic analyses did not support that the UGT1A1 promoter polymorphism could affect flavopiridol pharmacokinetics and alter the incidence and severity of diarrhea induced by the drug.

Topics: Adult; Aged; Antineoplastic Agents; Area Under Curve; Biological Availability; Cyclin-Dependent Kinases; Dose-Response Relationship, Drug; Female; Flavonoids; Genotype; Glucuronosyltransferase; Half-Life; Humans; Infusions, Intravenous; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms; Pharmacogenetics; Pharmacology, Clinical; Piperidines; Treatment Outcome

Flavopiridol is a flavonoid with antiproliferative effects mediated, in part, by inhibition of cyclin-dependent kinases. Clinical manifestations in a previous Phase I trial in patients with refractory malignancies treated with a 72-h flavopiridol infusion included a proinflammatory syndrome consisting of fever, fatigue, and "local" tumor pain with concomitant alterations in plasma acute-phase reactant proteins.. The aim of this study was to determine whether the proinflammatory syndrome observed in this trial was associated with modulation of plasma cytokines.. Patients receiving flavopiridol (n = 76) had serial plasma samples drawn preinfusion and during the infusion for evaluation of interleukin (IL)-6, IL-10, IL-12, granulocyte macrophage colony-stimulating factor, basic-fibroblast growth factor, transforming growth factor-beta, and tumor necrosis factor-alpha levels by standard ELISA assays. The Wilcoxon signed rank test was used to test the significance of the difference between the baseline (time 0) plasma cytokine levels compared with the values of each subsequent data collection time points (8, 24, 48, and 72 h).. There was a significant and sustained increase in plasma IL-6 levels at all time points when compared with baseline values. Paired values were used in the statistical analysis. Median plasma (interquartile range) values of IL-6 were elevated from 15.5 (9-52) pg/ml at baseline to 23 (4-48) pg/ml (P < 0.01) at 8 h; from 15 (2-48) pg/ml at baseline to 46 (21-105) pg/ml (P < 0.001) at 24 h; from 16 (9-52) pg/ml at baseline to 61 (32-170) pg/ml (P < 0.001) at 48 h; and from 15.5 (6-48) pg/ml to 68 (40-200) pg/ml (P < 0.001) at 72 h. Significance was maintained even when adjusted for multiple comparisons. The relative increase in IL-6 concentration was dose-dependent. Moreover, IL-6 elevation had a direct correlation with flavopiridol peak plasma concentration, flavopiridol area under the curve, and plasma C-Reactive protein levels. A significant decrease in plasma granulocyte macrophage colony-stimulating factor occurred at the 8-h sampling point: 50 pg/ml (interquartile range 10-205 pg/ml, P < 0.01) when compared with baseline plasma levels and 71 pg/ml (interquartile range 5-152 pg/ml, P < 0.01). No changes in the other pro or anti-inflammatory cytokines were observed. Immunohistochemistry studies in bone marrow aspirates from a prospective group of patients in this trial demonstrated approximately 4-fold induction of IL-6 (compared with baseline), mostly in non-T cells.. Biochemical analysis of plasma in patients undergoing infusional flavopiridol found a significant dose-dependent induction of IL-6. IL-6 elevation could be a marker for the process leading to the appearance of the proinflammatory syndrome observed in patients treated with infusional flavopiridol. The mechanism(s) underlying IL-6 induction and its significance are still unknown but may influence strategies to modulate flavopiridol's clinical effects.

Topics: Antineoplastic Agents; Bone Marrow; Cyclin-Dependent Kinases; Enzyme Inhibitors; Flavonoids; Humans; Inflammation; Infusions, Intravenous; Interleukin-6; Interleukins; Neoplasms; Piperidines

Flavopiridol, a novel flavone derivative, inhibits cyclin-dependent kinase-1. We initiated a Phase I trial in patients with refractory solid tumors to determine the maximum tolerated dose and characterize the adverse effect profile.. To characterize the clinical pharmacology of flavopiridol.. Serial plasma samples were collected and analyzed by HPLC using electrochemical detection. The pharmacokinetics were analyzed by noncompartmental analysis. Enterohepatic recirculation was studied by analyzing fecal samples, with an attempt to correlate cholecystokinin and post-infusional peak concentrations. The plasma protein binding was studied using equilibrium dialysis.. Seventy-six patients were treated with flavopiridol at 13 dose levels for a total of 504 cycles of treatment. The average steady-state concentration was 26.5 and 253 nM at 4 and 122.5 mg/m2, respectively. The clearance ranged from 49.9 to 2943 mL/min, with nonlinearity at doses >50 mg/m2/d. A post-infusional increase in plasma flavopiridol concentrations was noted in a subset of patients and generally occurred between 3 and 24 hours after the end of infusion. Flavopiridol was found in fecal matter, suggesting enterohepatic recirculation. There was nonsaturable plasma protein binding of flavopiridol (fu = 6%).. The dose-limiting toxicity for the Phase I trial of flavopiridol was secretory diarrhea. We failed to identify a clear relationship between dose or concentration and diarrhea. At 50 and 78 mg/m2/d, the mean steady-state plasma concentrations were 278 and 390 nM. These concentrations were well above those noted for in vitro antiproliferative activity. Nonlinear elimination was observed at doses above 50 mg/m2/d, and postinfusional peaks appear to be related to enterohepatic recirculation.

Topics: Adult; Aged; Diarrhea; Feces; Female; Flavonoids; Food; Humans; Infusions, Intravenous; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms; Pharmacology, Clinical; Piperidines; Protein Binding; Time Factors

To define the maximum-tolerated dose (MTD), dose-limiting toxicity, and pharmacokinetics of the cyclin-dependent kinase inhibitor flavopiridol administered as a daily 1-hour infusion every 3 weeks.. Fifty-five patients with advanced neoplasms were treated with flavopiridol at doses of 12, 17, 24, 30, 37.5, and 52.5 mg/m(2)/d for 5 days; doses of 50 and 62.5 mg/m(2)/d for 3 days; and doses of 62.5 and 78 mg/m(2)/d for 1 day. Plasma sampling was performed to characterize the pharmacokinetics of flavopiridol with these schedules.. Dose-limiting neutropenia developed at doses >/= 52.5 mg/m(2)/d. Nonhematologic toxicities included nausea, vomiting, diarrhea, hypotension, and a proinflammatory syndrome characterized by anorexia, fatigue, fever, and tumor pain. The median peak concentrations of flavopiridol achieved at the MTDs on the 5-day, 3-day, and 1-day schedule were 1.7 micro mol/L (range, 1.3 to 4.2 micro mol/L), 3.2 micro mol/L (range, 1.7 to 4.8 micro mol/L), and 3.9 micro mol/L (1.8 to 5.1 micro mol/L), respectively. Twelve patients had stable disease for >/= 3 months, with a median duration of 6 months (range, 3 to 11 months).. The recommended phase II doses of flavopiridol as a 1-hour infusion are 37.5 mg/m(2)/d for 5 days, 50 mg/m(2)/d for 3 days, and 62.5 mg/m(2)/d for 1 day. Flavopiridol as a daily 1-hour infusion can be safely administered and can achieve concentrations in the micromolar range, sufficient to inhibit cyclin-dependent kinases in preclinical models. Further studies to determine the optimal schedule of flavopiridol as a single agent and in combination with chemotherapeutic agents are underway.

Topics: Adult; Aged; Antineoplastic Agents; Area Under Curve; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Flavonoids; Humans; Infusions, Intravenous; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms; Neutropenia; Piperidines; Treatment Outcome

Flavopiridol (NSC 649890) is a synthetic flavone possessing significant antitumor activity in preclinical models. Flavopiridol is capable of inducing cell cycle arrest and apoptosis, presumably through its potent, specific inhibition of cyclin-dependent kinases. We conducted a phase I trial and pharmacokinetic study of flavopiridol given as a 72-h continuous intravenous infusion repeated every 2 weeks.. A total of 38 patients were treated at dose levels of 8, 16, 26.6, 40, 50 and 56 mg/m(2)/24 h. During the first infusion, plasma was sampled at 24, 48 and 72 h to determine steady-state concentrations, and peripheral blood lymphocytes were assessed by flow cytometry for evidence of apoptosis. Additional postinfusion pharmacokinetic sampling was done at the 40 and 50 mg/m(2)/24 h dose levels.. Gastrointestinal toxicity was dose limiting, with diarrhea being the predominant symptom. Symptomatic orthostatic hypotension was also frequently noted. Several patients experienced tumor-specific pain during their infusions. The maximum tolerated dose (MTD) was determined to be 40 mg/m(2)/24 h. A patient with metastatic gastric cancer at this dose level had a complete response and remained disease-free for more than 48 months after completing therapy. Plasma concentrations at 24 h into the infusion were 94% of those achieved at steady state. Steady-state plasma flavopiridol concentrations at the MTD were 416.6+/-98.9 micro M. These concentrations are at or above those needed to see cell cycle arrest and apoptosis in vitro. The mean clearance of flavopiridol over the dose range was 11.3+/-3.9 l/h per m(2), similar to values obtained preclinically. Elimination was biphasic. The terminal half-life at the MTD was 26.0 h. No significant differences in pharmacokinetic parameters were noted between males and females. Patients taking cholestyramine to ameliorate flavopiridol-induced diarrhea had lower steady-state plasma concentrations. There was no significant change in the cell cycle parameters of peripheral blood lymphocytes analyzed by flow cytometry.. The MTD and recommended phase II dose of flavopiridol given by this schedule is 40 mg/m(2)/24 h. The manageable gastrointestinal toxicity, early signs of clinical activity and lack of hematologic toxicity make further exploration in combination trials warranted.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Cyclin-Dependent Kinases; Dose-Response Relationship, Drug; Enzyme Inhibitors; Female; Flavonoids; Flow Cytometry; Half-Life; Humans; Infusions, Intravenous; Male; Maximum Tolerated Dose; Metabolic Clearance Rate; Middle Aged; Neoplasms; Piperidines; Safety; Treatment Outcome

Preclinical studies indicate that the cyclin-dependent kinase inhibitor flavopiridol potentiates the induction of apoptosis by paclitaxel, provided paclitaxel is followed by flavopiridol. We therefore designed a phase I clinical trial of sequential paclitaxel and flavopiridol.. Paclitaxel was administered at a fixed dose, as either a 24- or 3-hour infusion on day 1, followed by a 24-hour infusion of flavopiridol on day 2. Doses of flavopiridol were escalated in successive cohorts according to a modified Fibonacci design. Flavopiridol pharmacokinetics were obtained on all patients.. Dose-limiting neutropenia developed with 24-hour paclitaxel doses of 135 and 100 mg/m(2) and flavopiridol doses of 10 and 20 mg/m(2), respectively. With 3-hour paclitaxel at 100 mg/m(2), flavopiridol could be escalated to 70 mg/m(2) without dose-limiting toxicity. With 3-hour paclitaxel next escalated to 135 mg/m(2), dose-limiting neutropenia and pulmonary toxicity occurred when flavopiridol was escalated to 94 mg/m(2). This did not correlate with any change in flavopiridol or paclitaxel pharmacokinetics. At a 3-hour paclitaxel dose of 175 mg/m(2), dose-limiting pulmonary toxicity occurred in only one patient at flavopiridol doses under 94 mg/m(2). Clinical activity was observed in patients with esophagus, lung, and prostate cancer, including patients who had progressed on paclitaxel.. The recommended phase II doses will be a 3-hour infusion of paclitaxel at 175 mg/m(2) on day 1 followed by a 24-hour infusion of flavopiridol at 70 mg/m(2) on day 2. Flavopiridol dose escalations to 80 mg/m(2) are possible. At these doses, toxicities are manageable and clinical activity is promising.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Cyclin-Dependent Kinases; Female; Flavonoids; Humans; Male; Middle Aged; Neoplasms; Paclitaxel; Piperidines

We conducted a phase I trial of the cyclin-dependent kinase inhibitor, flavopiridol (National Service Center [NSC] 649890), to determine the maximum-tolerated dose (MTD), toxicity profile, and pharmacology of flavopiridol given as a 72-hour infusion every 2 weeks.. Seventy-six patients with refractory malignancies with prior disease progression were treated with flavopiridol, with first-cycle pharmacokinetic sampling.. Forty-nine patients defined our first MTD, 50 mg/m2/d x 3 with dose-limiting toxicity (DLT) of secretory diarrhea at 62.5 mg/kg/d x 3. Subsequent patients received antidiarrheal prophylaxis (ADP) to define a second MTD, 78 mg/m2/d x 3 with DLT of hypotension at 98 mg/m2/d x 3. Other toxicities included a proinflammatory syndrome with alterations in acute-phase reactants, particularly at doses >50 mg/ m2/d x 3, which in some patients prevented chronic therapy every 2 weeks. In some patients, ADP was not successful, requiring dose-deescalation. Although approximately 70% of patients displayed predictable flavopiridol pharmacology, we observed unexpected interpatient variability and postinfusion peaks in approximately 30% of cases. At the two MTDs, we achieved a mean plasma flavopiridol concentration of 271 nM (50 mg/m2/d x 3) and 344 nM (78 mg/m2/d x 3), respectively. One partial response in a patient with renal cancer and minor responses (n=3) in patients with non-Hodgkin's lymphoma, colon, and renal cancer occurred.. The MTD of infusional flavopiridol is 50 mg/m2/d x 3 with dose-limiting secretory diarrhea at 62.5 mg/m2/d x 3. With ADP, 78 mg/m2/d x 3 was the MTD, with dose-limiting hypotension at 98 mg/m2/d x 3. Based on chronic tolerability, 50 mg/m2/d x 3 is the recommended phase II dose without ADP. Antitumor effect was observed in certain patients with renal, prostate, and colon cancer, and non-Hodgkin's lymphoma. Concentrations of flavopiridol (200 to 400 nM) needed for cyclin-dependent kinase inhibition in preclinical models were achieved safely.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Cyclin-Dependent Kinases; Diarrhea; Dose-Response Relationship, Drug; Drug Administration Schedule; Enzyme Inhibitors; Female; Flavonoids; Humans; Infusions, Intravenous; Male; Middle Aged; Neoplasms; Piperidines

Cyclin dependent kinase (CDK) inhibitors have been the topic of intense research for nearly 2 decades due to their widely varied and critical functions within the cell. Recently CDK9 has emerged as a druggable target for the development of cancer therapeutics. CDK9 plays a crucial role in transcription regulation; specifically, CDK9 mediated transcriptional regulation of short-lived antiapoptotic proteins is critical for the survival of transformed cells. Focused chemical libraries based on a plethora of scaffolds have resulted in mixed success with regard to the development of selective CDK9 inhibitors. Here we review the regulation of CDK9, its cellular functions, and common core structures used to target CDK9, along with their selectivity profile and efficacy in vitro and in vivo.

Topics: Animals; Cyclin-Dependent Kinase 9; Drug Discovery; Flavonoids; Humans; Macrocyclic Compounds; Models, Molecular; Neoplasms; Protein Kinase Inhibitors; Purines; Pyrazoles; Pyrimidines; Triazines

Cancer cells appear to depend heavily on antiapoptotic proteins for survival and so targeted inhibition of these proteins has therapeutic potential. One innovative strategy is to inhibit the cyclin-dependent kinases (CDKs) responsible for the regulation of RNA polymerase II (RNAPII). In our study, we investigated the detailed cellular mechanism of a novel small-molecule CDK inhibitor (CDKI-71) in cancer cell lines, primary leukemia cells, normal B - & T- cells, and embryonic lung fibroblasts and compared the cellular and molecular responses to the clinical CDK inhibitor, flavopiridol. Like flavopiridol, CDKI-71 displayed potent cytotoxicity and caspase-dependent apoptosis induction that were closely associated with the inhibition of RNAPII phosphorylation at serine-2. This was caused by effective targeting of cyclinT-CDK9 and resulted in the downstream inhibition of Mcl-1. No correlation between apoptosis and inhibition of cell-cycle CDKs 1 and 2 was observed. CDKI-71 showed a 10-fold increase in potency in tumor cell lines when compared to MRC-5 human fibroblast cells. Significantly, CDKI-71 also demonstrated potent anti-chronic lymphocytic leukemia activity with minimal toxicity in normal B- and T-cells. In contrast, flavopiridol showed little selectivity between cancer and normal cells. Here, we provide the first cell-based evidence that flavopiridol induces DNA double-strand breaks: a fact which may explain why flavopiridol has such a narrow therapeutic window in preclinical and clinical settings. Taken together, our data provide a rationale for the development of selective CDK inhibitors as therapeutic agents and CDKI-71 represents a promising lead in this context.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase 9; Drug Evaluation, Preclinical; Enzyme Inhibitors; Flavonoids; Humans; Neoplasms; Piperidines; Sulfonamides

In the present article, we have synthesized a combinatorial library of 3,5-diaryl pyrazole derivatives using 8-(2-(hydroxymethyl)-1-methylpyrrolidin-3-yl)-5,7-dimethoxy-2-phenyl-4H-chromen-4-one (1) and hydrazine hydrate in absolute ethyl alcohol under the refluxed conditions. The structures of the compounds were established by IR, (1)H NMR and mass spectral analysis. All the synthesized compounds were evaluated for their anticancer activity against five cell lines (breast cancer cell line, prostate cancer cell line, promyelocytic leukemia cell line, lung cancer cell line, colon cancer cell line) and anti-inflammatory activity against TNF-alpha and IL-6. Out of 15 compounds screened, 2a and 2d exhibited promising anticancer activity (61-73% at 10 microM concentration) against all selected cell lines and IL-6 inhibition (47% and 42% at 10 microM concentration) as in comparison to standard flavopiridol (72-87% inhibition at 0.5 microM) and dexamethasone (85% inhibition at 1 microM concentration), respectively. Cytotoxicity of the compounds checked using CCK-8 cell lines and found to be nontoxic to slightly toxic. Out of 15, four 3,5-diaryl pyrazole derivatives exhibiting potent inhibitory activities against both the monophenolase and diphenolase actions of tyrosinase. The IC(50) values of compounds (2a, 2d, 2h and 2l) for monophenolase inhibition were determined to range between 1.5 and 30 microM. Compounds 2a, 2d, 2h and 2l also inhibited diphenolase significantly with IC(50) values of 29.4, 21.5, 2.84 and 19.6 microM, respectively. All four 3,5-diaryl pyrazole derivatives were active as tyrosinase inhibitors (2a, 2d, 2h and 2l), and belonging to competitive inhibitors. Interestingly, they all manifested simple reversible slow-binding inhibition against diphenolase.

Topics: Agaricales; Anti-Inflammatory Agents; Antineoplastic Agents; Cell Line, Tumor; Cytokines; Drug Screening Assays, Antitumor; Humans; Models, Molecular; Monophenol Monooxygenase; Neoplasms; Pyrazoles

Rohitukine, a chromane alkaloid, is a precursor of flavopiridol, a promising anti-cancer compound. Currently in Phase III clinical trials, flavopiridol is a potent inhibitor of several cyclin-dependent kinases (CDKs). Rohitukine was first reported from Amoora rohituka (0.083% dry weight) followed by that in Dysoxylum binectariferum (0.9% dry weight), both belonging to the family Meliaceae. Here, we report incredibly high yields of rohitukine (7% dry weight) in trees of D. binectariferum from the Western Ghats, India. Crude extracts of the tree were found to be highly effective against ovarian and breast cancer lines tested.

Topics: Antineoplastic Agents, Phytogenic; Breast Neoplasms; Cell Line, Tumor; Female; Flavonoids; Humans; India; Limonins; Meliaceae; Neoplasms; Ovarian Neoplasms; Phytotherapy; Piperidines; Plant Bark; Plant Extracts; Plant Stems; Protein Kinase Inhibitors; Trees

A bottleneck in drug discovery is the identification of the molecular targets of a compound (mode of action, MoA) and of its off-target effects. Previous approaches to elucidate drug MoA include analysis of chemical structures, transcriptional responses following treatment, and text mining. Methods based on transcriptional responses require the least amount of information and can be quickly applied to new compounds. Available methods are inefficient and are not able to support network pharmacology. We developed an automatic and robust approach that exploits similarity in gene expression profiles following drug treatment, across multiple cell lines and dosages, to predict similarities in drug effect and MoA. We constructed a "drug network" of 1,302 nodes (drugs) and 41,047 edges (indicating similarities between pair of drugs). We applied network theory, partitioning drugs into groups of densely interconnected nodes (i.e., communities). These communities are significantly enriched for compounds with similar MoA, or acting on the same pathway, and can be used to identify the compound-targeted biological pathways. New compounds can be integrated into the network to predict their therapeutic and off-target effects. Using this network, we correctly predicted the MoA for nine anticancer compounds, and we were able to discover an unreported effect for a well-known drug. We verified an unexpected similarity between cyclin-dependent kinase 2 inhibitors and Topoisomerase inhibitors. We discovered that Fasudil (a Rho-kinase inhibitor) might be "repositioned" as an enhancer of cellular autophagy, potentially applicable to several neurodegenerative disorders. Our approach was implemented in a tool (Mode of Action by NeTwoRk Analysis, MANTRA, http://mantra.tigem.it).

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Algorithms; Antineoplastic Agents; Autophagy; Blotting, Western; Camptothecin; Cell Line, Tumor; Doxorubicin; Drug Discovery; Drug Screening Assays, Antitumor; Flavonoids; Fuzzy Logic; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; HeLa Cells; Humans; Irinotecan; Neoplasms; Oligonucleotide Array Sequence Analysis; Phosphorylation; Piperidines; Pyrazoles; Pyrroles; RNA Polymerase II

Although flavopiridol, a semisynthetic flavone, was initially thought to be a specific inhibitor of cyclin-dependent kinases, it has now been shown that flavopiridol mediates antitumor responses through mechanism(s) yet to be defined. We have shown previously that flavopiridol abrogates tumor necrosis factor (TNF)-induced nuclear factor-kappaB (NF-kappaB) activation. In this report, we examined whether this flavone affects other cellular responses activated by TNF. TNF is a potent inducer of activator protein-1 (AP-1), and flavopiridol abrogated this activation in a dose- and time-dependent manner. Flavopiridol also suppressed AP-1 activation induced by various carcinogens and inflammatory stimuli. When examined for its effect on other signaling pathways, flavopiridol inhibited TNF-induced activation of various mitogen-activated protein kinases, including c-Jun NH(2)-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and p44/p42 MAPK. It is noteworthy that this flavone also suppressed TNF-induced activation of Akt, a cell survival kinase, and expression of various antiapoptotic proteins, such as IAP-1, IAP-2, XIAP, Bcl-2, Bcl-xL, and TRAF-1. Flavopiridol also inhibited the TNF-induced induction of intercellular adhesion molecule-1, c-Myc, and c-Fos, all known to mediate tumorigenesis. Moreover, TNF-induced apoptosis was enhanced by flavopiridol through activation of the bid-cytochrome-caspase-9-caspase-3 pathway. Overall, our results clearly suggest that flavopiridol interferes with the TNF cell-signaling pathway, leading to suppression of antiapoptotic mechanisms and enhancement of apoptosis.

Topics: Apoptosis; Apoptosis Regulatory Proteins; Caspases; Cell Line; Cell Nucleus; Cell Proliferation; Cytochromes c; Enzyme Activation; Flavonoids; Gene Expression Regulation; Genes, Reporter; Humans; Intercellular Adhesion Molecule-1; JNK Mitogen-Activated Protein Kinases; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases; Myeloid Cells; Neoplasms; p38 Mitogen-Activated Protein Kinases; Piperidines; Protein Transport; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-fos; Proto-Oncogene Proteins c-myc; Transcription Factor AP-1; Tumor Necrosis Factors

Selective cyclin-dependent kinase (cdk) 2 inhibition is readily compensated. However, reduced cdk2 activity may have antiproliferative effects in concert with other family members. Here, inducible RNA interference was used to codeplete cdk2 and cdk1 from NCI-H1299 non-small cell lung cancer and U2OS osteosarcoma cells, and effects were compared with those mediated by depletion of either cdk alone. Depletion of cdk2 slowed G1 progression of NCI-H1299 cells and depletion of cdk1 slowed G2-M progression in both cell lines, with associated endoreduplication in U2OS cells. However, compared with the incomplete cell cycle blocks produced by individual depletion, combined depletion had substantial consequences, with G2-M arrest predominating in NCI-H1299 cells and apoptosis the primary outcome in U2OS cells. In U2OS cells, combined depletion affected RNA polymerase II expression and phosphorylation, causing decreased expression of the antiapoptotic proteins Mcl-1 and X-linked inhibitor of apoptosis (XIAP), effects usually mediated by inhibition of the transcriptional cdk9. These events do not occur after individual depletion of cdk2 and cdk1, suggesting that reduction of cdk2, cdk1, and RNA polymerase II activities all contribute to apoptosis in U2OS cells. The limited cell death induced by combined depletion in NCI-H1299 cells was significantly increased by codepletion of cdk9 or XIAP or by simultaneous treatment with the cdk9 inhibitor flavopiridol. These results show the potency of concomitant compromise of cell cycle and transcriptional cdk activities and may guide the selection of clinical drug candidates.

Topics: Apoptosis; Bone Neoplasms; Carcinoma, Non-Small-Cell Lung; CDC2 Protein Kinase; Cell Division; Cell Line, Tumor; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase 9; Flavonoids; G1 Phase; G2 Phase; Humans; Lung Neoplasms; Neoplasms; Osteosarcoma; Piperidines; RNA Polymerase II; RNA, Small Interfering

We examined the efficacy of flavopiridol, a cyclin-dependent kinase inhibitor that is undergoing clinical trials, on primary cancer cells isolated from the ascites or pleural fluids of patients with metastatic cancers.. Metastasized cancer cells were isolated from the pleural fluids (n = 20) or ascites (n = 15) of patients, most of whom were refractory to chemotherapy. These primary cancer cells were used within 2 weeks of isolation without selecting for proliferative capacities. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide viability assay was used to characterize the response of these cancer cells to commonly used chemotherapeutic agents, and their response to flavopiridol was compared with rapidly dividing cultured cell lines.. The primary cancer cells displayed phenotypes that were different from established cell lines; they had very low replication rates, dividing every 1 to 2 weeks, and underwent replicative senescence within five passages. These primary tumor cells retained their resistance to chemotherapeutic drugs exhibited by the respective patients but did not show cross-resistance to other agents. However, these cancer cells showed sensitivity to flavopiridol with an average LD50 of 50 nmol/L (range, 21.5-69 nmol/L), similar to the LD50 in established cell lines. Because senescent cells also showed similar sensitivity to flavopiridol, it suggests that the mechanism of action is not dependent on the activity of cyclin-dependent kinases that regulate the progression of the cell cycle.. Using cancer cells isolated from the ascites or pleural fluids, this study shows the potential of flavopiridol against cancer cells that have developed resistance to conventional chemotherapeutic agents.

Topics: Antineoplastic Agents; Ascites; Blotting, Western; Carboplatin; Cell Line, Tumor; Cell Proliferation; Cisplatin; Cyclin-Dependent Kinases; Dose-Response Relationship, Drug; Doxorubicin; Flavonoids; Humans; Neoplasms; Paclitaxel; Piperidines; Pleural Effusion, Malignant; Proto-Oncogene Proteins c-bcl-2; Time Factors; Tumor Cells, Cultured

Flavopiridol has been shown to inhibit the proliferation of a variety of human tumor cells and is currently undergoing clinical evaluation in cancer treatment. Although the antiproliferative effect of flavopiridol has been attributed to the inhibition of cyclin-dependent kinases 2 and 4, recent reports indicate that the mechanism responsible for the cell death induced by this agent is more complex. To provide insight into the molecular processes mediating flavopiridol-induced cytotoxicity and to investigate the availability of markers indicative of its activity, we have applied cDNA microarray technology. Gene expression profiles were determined for four human tumor cell lines (prostate carcinomas PC3 and DU145 and gliomas SF359 and U251) following exposure to selected concentrations of flavopiridol. Treatment of these cell lines with a concentration of flavopiridol sufficient to reduce survival to 10% resulted in the identification of a set of 209 genes, the expression of which were altered in each of the cell lines. This common set of 209 gene expression changes suggested that flavopiridol-induced cell death can be defined in terms of a specific transcriptome. The flavopiridol death transcriptome consisted primarily of down-regulated genes; however, there were also a significant number of genes with increased expression. Whereas causal relationships were not established, these data suggest molecular events/processes that may be associated with flavopiridol-induced tumor cell death. Moreover, the identification of a set of gene expression changes in four human tumor cell lines suggests that such a transcriptome may be applicable to investigations of flavopiridol pharmacodynamics.

Topics: Antineoplastic Agents; Cell Death; Cell Line, Tumor; Flavonoids; Gene Expression Profiling; Humans; Neoplasms; Oligonucleotide Array Sequence Analysis; Piperidines; RNA, Messenger; RNA, Neoplasm; Transcription, Genetic

Topics: Antineoplastic Agents; Clinical Trials as Topic; Cyclin-Dependent Kinases; Drug Evaluation, Preclinical; Enzyme Inhibitors; Flavonoids; Humans; Neoplasms; Piperidines