desoxyepothilone-b and Breast-Neoplasms

Standard cytotoxic chemotherapy of locally advanced or metastatic breast cancer includes the microtubule-stabilizing taxanes, but like other cytotoxic drugs their effectiveness is compromised by resistance that is either inherent or develops during treatment. Epothilones, which also stabilize microtubules but by a different mechanism, are in clinical development primarily to overcome taxane or multidrug resistance, based on potent preclinical antitumor activity against resistant tumor lines. Ixabepilone is the best-studied epothilone clinically and is active in patients with metastatic breast cancer that has been pretreated with, or had established resistance to, taxanes and/or anthracyclines. In a phase III trial in patients with anthracycline-pretreated or -resistant and taxane-resistant locally advanced or metastatic breast cancer, adding ixabepilone to capecitabine significantly improved progression-free survival and the overall response rate compared with capecitabine alone. The primary toxicities associated with ixabepilone treatment are neuropathy and neutropenia, but both are generally manageable. Other epothilones currently in clinical studies are KOS-862, patupilone, ZK-EPO, BMS-310705, and KOS-1584, which have all shown activity in patients with pretreated or resistant metastatic breast cancer.

Topics: Breast Neoplasms; Capecitabine; Clinical Trials, Phase III as Topic; Deoxycytidine; Disease Progression; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Resistance, Neoplasm; Epothilones; Female; Fluorouracil; Humans; Neoplasm Metastasis; Tubulin Modulators

The epothilones constitute a novel class of microtubule inhibitors that act like the taxanes by hyperstabilizing tubulin polymerization, thus disrupting functioning of the mitotic spindle. Natural epothilones produced by myxobacteria, and second- or third-generation partially or fully synthesized analogs, have been explored as cancer chemotherapy agents to replace or follow the taxanes. For those epothilones that have gone on to clinical development (epothilone B, ixabepilone, BMS-310705, ZK-EPO, KOS-862, and KOS-1584), preclinical investigations in breast cancer models are reviewed. All of these epothilones improve upon the cytotoxic activity of paclitaxel in various human breast cancer cell lines in vitro, but are also highly active in lines that are resistant to paclitaxel. Comparable antitumor activity has been demonstrated against nude mouse xenografts of paclitaxel-sensitive and -resistant breast cancer lines. Additionally, some analogs have reduced toxicity or increased water solubility that may permit oral administration, while others with enhanced tissue penetration show promise in animal models of breast cancer brain or bone metastasis and may provide benefits in patients with poor-prognosis advanced breast cancer.

Topics: Animals; Antineoplastic Agents; Bone Neoplasms; Breast Neoplasms; Capecitabine; Cell Line, Tumor; Clinical Trials, Phase I as Topic; Deoxycytidine; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Design; Drug Evaluation, Preclinical; Epothilones; Female; Fluorouracil; Humans; Mice; Mice, Nude; Microtubules; Paclitaxel; Tubulin Modulators

Epothilone D (Epo D) and its 9-Methyl conformational analogues were synthesized through a highly efficient combinatorial approach. The fragment E was synthesized in 11 total steps with 6 longest linear steps, and each aldehyde B was prepared via a 3-step sequence. Starting from the common precursor E and a suitable aldehydes B, each target molecule were obtained in only 4 steps. The 9-(S)-epo D and 9-(R)-epo D demonstrated significant difference in inhibition activities against cancer cell lines and in conformational analysis.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Combinatorial Chemistry Techniques; Computer Simulation; Crystallography, X-Ray; Epothilones; Female; Humans; Inhibitory Concentration 50; Models, Biological; Molecular Structure

Desoxyepothilone B (dEpoB), currently in clinical trials, is a novel microtubule inhibitor with similar mode-of-action to paclitaxel (Taxol). Intriguingly, it is effective in some cell lines and tumor xenografts refractory to Taxol. The purpose of this study is to compare signaling induced by the two drugs and identify a molecular basis for increased efficacy of dEpoB in resistant lines. The importance of ERK signaling, already established for Taxol, was shown for dEpoB and other G2-blocking agents. However, a role in differential sensitivity was not observed. Affymetrix analysis shows similar gene modulation by either agent, alone or in combination with MEK inhibitor. Differential sensitivity in a set of Taxol-resistant lines correlated to the expression of P-glycoprotein (P-gp), and its importance was demonstrated directly. These results suggest that Taxol and dEpoB elicit similar cell death pathways, and the increased efficacy of dEpoB in resistant tumor lines lies in differential susceptibility to P-gp.

Topics: Adenocarcinoma; Antineoplastic Agents, Phytogenic; ATP Binding Cassette Transporter, Subfamily B, Member 1; Breast Neoplasms; Cell Death; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Epothilones; Female; Humans; Lung Neoplasms; Paclitaxel; Signal Transduction; Tumor Cells, Cultured

A new epothilone, 10,11-didehydroepothilone D (5), was isolated from a strain of the heterologous host Myxococcus xanthus genetically engineered to produce epothilone D (4). The structure of 5 was determined from NMR and MS data. The epothilone polyketide synthase was further modified in a recombinant M. xanthus strain to produce 5 as the major epothilone-related metabolite. The cytotoxicity of 5 against a panel of tumor cell lines, including several with multidrug resistance, and its effect on tubulin polymerization were comparable to epothilone D (4).

Topics: Antineoplastic Agents; Base Sequence; Binding Sites; Breast Neoplasms; Drug Screening Assays, Antitumor; Epothilones; Epoxy Compounds; Female; Genetic Engineering; Glioma; HL-60 Cells; Humans; Inhibitory Concentration 50; Leukemia, Promyelocytic, Acute; Leukemia, T-Cell; Lung Neoplasms; Mass Spectrometry; Molecular Sequence Data; Molecular Structure; Multienzyme Complexes; Myxococcus xanthus; Nuclear Magnetic Resonance, Biomolecular; Thiazoles; Tubulin; Tumor Cells, Cultured

The epothilones are naturally occurring, cytotoxic macrolides that function through a paclitaxel (Taxol)-like mechanism. Although structurally dissimilar, both classes of molecules lead to the arrest of cell division and eventual cell death by stabilizing cellular microtubule assemblies. The epothilones differ in their ability to retain activity against multidrug-resistant (MDR) cell lines and tumors where paclitaxel fails. In the current account, we focus on the relationship between epothilone and paclitaxel in the context of tumors with multiple drug resistance. The epothilone analogue Z-12,13-desoxyepothilone B (dEpoB) is >35,000-fold more potent than paclitaxel in inhibiting cell growth in the MDR DC-3F/ADX cell line. Various formulations, routes, and schedules of i.v. administration of dEpoB have been tested in nude mice. Slow infusion with a Cremophor-ethanol vehicle proved to be the most beneficial in increasing efficacy and decreasing toxicity. Although dEpoB performed similarly to paclitaxel in sensitive tumors xenografts (MX-1 human mammary and HT-29 colon tumor), its effects were clearly superior against MDR tumors. When dEpoB was administered to nude mice bearing our MDR human lymphoblastic T cell leukemia (CCRF-CEM/paclitaxel), dEpoB demonstrated a full curative effect. For human mammary adenocarcinoma MCF-7/Adr cells refractory to paclitaxel, dEpoB reduced the established tumors, markedly suppressed tumor growth, and surpassed other commonly used chemotherapy drugs such as adriamycin, vinblastine, and etoposide in beneficial effects.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Cell Survival; Drug Resistance, Neoplasm; Epothilones; Female; Humans; Lactones; Leukemia P388; Leukemia-Lymphoma, Adult T-Cell; Mice; Mice, Nude; Ovarian Neoplasms; Paclitaxel; Structure-Activity Relationship; Thiazoles; Transplantation, Heterologous; Tumor Cells, Cultured