scholarly journals Characterisation of Zampanolide as a Microtubule-Stabilizing Agent

2021 ◽  
Author(s):  
◽  
Jessica J. Field
Keyword(s):  
Binding Site ◽  
Cell Lines ◽  
Efflux Pump ◽  
Covalent Binding ◽  
Covalent Modification ◽  
Cancer Drug ◽  
Side Chain ◽  
Drug Efflux ◽  
New Generation

<p>Microtubule-stabilizing agents (MSAs) are extremely important chemotherapeutic drugs since microtubules (MTs) are one of the most successful cancer drug targets. Currently there are four MSAs that are clinically used for the treatment of cancer. Cancer cells, however, can develop resistance towards these drugs, the most common being over-expression of the P-glycoprotein drug efflux pump. Zampanolide (ZMP), a novel secondary metabolite isolated from a marine sponge consists of a 20-membered macrolide ring with an unusual N-acyl-hemiaminal side chain. It is a potent MSA with similar cellular effects to the clinically relevant MSAs, Taxol®, Taxotere® and Ixempra®. ZMP has a small number of stereogenic centers and therefore is relatively easier to synthesize than other macrolide natural products. Using established cancer cell lines and isolated bovine brain tubulin ZMP in the present study was further characterized as a potential anti-cancer compound and was shown to have significant advantages over currently used MSAs. These studies provided insight into how this important drug class induces MT assembly, suggesting strategies for the development of new generation MSAs for use in the clinic. ZMP and its less active analog dactylolide competed with paclitaxel for binding to MTs and represented a novel MSA chemotype. Unlike traditional taxoid site ligands, ZMP remained significantly more cytotoxic in cell lines with mutations in the taxoid binding site, and behaved in an unusual manner in vitro. This was later found to be due to its mechanism of binding which involved covalent modification of two amino acids in the taxoid binding site, histidine 229 as the major product and asparagine 228 as the minor product. Alkylation of both these luminal site residues was also detected in unassembled tubulin, providing the first direct evidence that the taxoid binding site exists in unassembled tubulin and suggesting that the induction of MT nucleation by MSAs may proceed through an allosteric mechanism. X-ray crystallography data confirmed the presence of this binding site in unassembled tubulin and indicated that covalent modification occurs at C9 of ZMP with the NE2 of the histidine side chain. The potent stabilization of MTs observed with ZMP occurred due to its side chain interaction with the stabilizing M-loop of β-tubulin. In unassembled tubulin the M-loop is unordered. Upon ZMP binding, it is restructured into a short, well-defined helix. It is this restructuring that leads to the potent stabilization by ZMP and most likely other MSAs, including those currently used in the clinic. This information provides a basis for structure-guided drug engineering to design and develop new generation MSAs with potent stabilizing activity. In addition, covalent binding of ZMP means that it is able to avoid drug efflux pumps and thus evade the main mechanism of resistance presented to MSAs in the clinic. It was shown by studying structure-activity relationships that there are a number of key chemical motifs in ZMP responsible for its potent activity. Simpler analog structures that retain significant stabilizing activity could be used as lead compounds for further drug development. Moreover, MSAs have clinically relevant anti-angiogenic and vascular-disrupting properties, and ZMP was also shown to potently inhibit cell migration and thus have possible benefits as a vasculature-targeting compound. It was concluded that ZMP is a potent covalently-binding MSA in both cells and in vitro. Given these promising results, further preclinical development of the compound is warranted.</p>

scholarly journals Characterisation of Zampanolide as a Microtubule-Stabilizing Agent

2021 ◽  
Author(s):  
◽  
Jessica J. Field
Keyword(s):  
Binding Site ◽  
Cell Lines ◽  
Efflux Pump ◽  
Covalent Binding ◽  
Covalent Modification ◽  
Cancer Drug ◽  
Side Chain ◽  
Drug Efflux ◽  
New Generation

<p>Microtubule-stabilizing agents (MSAs) are extremely important chemotherapeutic drugs since microtubules (MTs) are one of the most successful cancer drug targets. Currently there are four MSAs that are clinically used for the treatment of cancer. Cancer cells, however, can develop resistance towards these drugs, the most common being over-expression of the P-glycoprotein drug efflux pump. Zampanolide (ZMP), a novel secondary metabolite isolated from a marine sponge consists of a 20-membered macrolide ring with an unusual N-acyl-hemiaminal side chain. It is a potent MSA with similar cellular effects to the clinically relevant MSAs, Taxol®, Taxotere® and Ixempra®. ZMP has a small number of stereogenic centers and therefore is relatively easier to synthesize than other macrolide natural products. Using established cancer cell lines and isolated bovine brain tubulin ZMP in the present study was further characterized as a potential anti-cancer compound and was shown to have significant advantages over currently used MSAs. These studies provided insight into how this important drug class induces MT assembly, suggesting strategies for the development of new generation MSAs for use in the clinic. ZMP and its less active analog dactylolide competed with paclitaxel for binding to MTs and represented a novel MSA chemotype. Unlike traditional taxoid site ligands, ZMP remained significantly more cytotoxic in cell lines with mutations in the taxoid binding site, and behaved in an unusual manner in vitro. This was later found to be due to its mechanism of binding which involved covalent modification of two amino acids in the taxoid binding site, histidine 229 as the major product and asparagine 228 as the minor product. Alkylation of both these luminal site residues was also detected in unassembled tubulin, providing the first direct evidence that the taxoid binding site exists in unassembled tubulin and suggesting that the induction of MT nucleation by MSAs may proceed through an allosteric mechanism. X-ray crystallography data confirmed the presence of this binding site in unassembled tubulin and indicated that covalent modification occurs at C9 of ZMP with the NE2 of the histidine side chain. The potent stabilization of MTs observed with ZMP occurred due to its side chain interaction with the stabilizing M-loop of β-tubulin. In unassembled tubulin the M-loop is unordered. Upon ZMP binding, it is restructured into a short, well-defined helix. It is this restructuring that leads to the potent stabilization by ZMP and most likely other MSAs, including those currently used in the clinic. This information provides a basis for structure-guided drug engineering to design and develop new generation MSAs with potent stabilizing activity. In addition, covalent binding of ZMP means that it is able to avoid drug efflux pumps and thus evade the main mechanism of resistance presented to MSAs in the clinic. It was shown by studying structure-activity relationships that there are a number of key chemical motifs in ZMP responsible for its potent activity. Simpler analog structures that retain significant stabilizing activity could be used as lead compounds for further drug development. Moreover, MSAs have clinically relevant anti-angiogenic and vascular-disrupting properties, and ZMP was also shown to potently inhibit cell migration and thus have possible benefits as a vasculature-targeting compound. It was concluded that ZMP is a potent covalently-binding MSA in both cells and in vitro. Given these promising results, further preclinical development of the compound is warranted.</p>

scholarly journals Confirmation of Selected Synergistic Cancer Drug Combinations Identified in an HTS Campaign and Exploration of Drug Efflux Transporter Contributions to the Mode of Synergy

2019 ◽  
Vol 24 (6) ◽  
pp. 653-668
Author(s):  
Stanton J. Kochanek ◽  
David A. Close ◽  
Allen Xinwei Wang ◽  
Tongying Shun ◽  
Philip E. Empey ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Cell Lines ◽  
Human Cancer ◽  
Tumor Cell Line ◽  
Drug Combinations ◽  
Cancer Drug ◽  
Drug Efflux ◽  
Efflux Transporter ◽  
Pharmacological Interaction

Systematic unbiased high-throughput screening (HTS) of drug combinations (DCs) in well-characterized tumor cell lines is a data-driven strategy to identify novel DCs with potential to be developed into effective therapies. Four DCs from a DC HTS campaign were selected for confirmation; only one appears in clinicaltrials.gov and limited preclinical in vitro data indicates that the drug pairs interact synergistically. Nineteen DC-tumor cell line sets were confirmed to interact synergistically in three pharmacological interaction models. We developed an imaging assay to quantify accumulation of the ABCG2 efflux transporter substrate Hoechst. Gefitinib and raloxifene enhanced Hoechst accumulation in ABCG2 (BCRP)-expressing cells, consistent with inhibition of ABCG2 efflux. Both drugs also inhibit ABCB1 efflux. Mitoxantrone, daunorubicin, and vinorelbine are substrates of one or more of the ABCG2, ABCB1, or ABCC1 efflux transporters expressed to varying extents in the selected cell lines. Interactions between ABC drug efflux transporter inhibitors and substrates may have contributed to the observed synergy; however, other mechanisms may be involved. Novel synergistic DCs identified by HTS were confirmed in vitro, and plausible mechanisms of action studied. Similar approaches may justify the testing of novel HTS-derived DCs in mouse xenograft human cancer models and support the clinical evaluation of effective in vivo DCs in patients.

Inhibition of RARα2 or Its Downstream Signaling Pathways Decreases Drug Resistance in Myeloma

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 989-989
Author(s):  
Guido J. Tricot ◽  
Ye Yang ◽  
Fang Xiao ◽  
Maurizio Zangari ◽  
Hongwei Xu ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Signaling Pathways ◽  
Cell Lines ◽  
Hedgehog Signaling ◽  
Efflux Pump ◽  
Conflicts Of Interest ◽  
Drug Efflux ◽  
Over Expression ◽  
Drug Efflux Pump

Abstract Abstract 989 Background: We have previously reported that the 30% of newly diagnosed myeloma (MM) patients expressing RARα2, had a significantly inferior outcome. RARα2 expression was also significantly increased in rapidly relapsing myelomas compared to paired baseline samples, indicating the existence at diagnosis of a RARα2 subclone, which is drug-resistant. We further demonstrated that RARα2 expression was significantly higher in MM cell line-derived and primary MM stem cells (MMSC) than in CD138+ bulk MM cells. In this study, we further explore the role of RARα2 in myeloma drug resistance. Materials and methods: RARα2 related drug resistance was evaluated by clonogenic formation assays, using 20,000 MM cells from the RARα2 high-expressing ARK and KMS11 MM cell lines, treated with all-trans retinoic acid (ATRA) (1nM, 10nM), Wnt inhibitor CAY10404 (1 nM, 10nM), Hedgehog inhibitor cyclopamine (1nM, 10nM), bortezomib (1nM, 10nM), as well as doxorubicin (50nM, 100nM), etoposide (50nM, 100nM), and verapamil (50nM). To determine whether inhibition of RARa2 decreased drug resistance, 1.0 × 106 KMS11 cells, made resistant to bortezomib, were transfected with RARα2 shRNA and injected subcutaneously into 20 NOD/SCID mice. The 5TGM1 myeloma mice were used to determine whether targeting RARa2 or its signaling pathways could eliminate MMSC. Results: After serial replating for 6 weeks, MMSCs (CD138- fraction) exhibited greater clonogenic expansion than the control CD138+ fraction, while ATRA, an inhibitor of RARα2, induced potent clonogenic inhibition on MMSC. We also showed in vitro that over-expression of RARα2 in low-expressing MM cell lines, ARP1 and OCI-MY5 resulted in increased clonogenic potential and drug-resistance. In a xenograft myeloma mouse model, knockdown of RARα2 in the KSM11bortezomib-resistant cells decreased resistance to bortezomib. We further identified that RARα2 induced drug resistance by activating the drug efflux pump gene ABCC3 through Wnt and Hedgehog signaling. Inhibition of Wnt (CAY10404) signaling or the ABC transporter by verapamil overcame the drug-resistance in ARP1 and OCI-MY5 cells caused by RARα2 over-expression. Finally, targeting RARa2 or its pathways using ATRA, CAY10404 and cyclopamine significantly reduced the tumor burden as determined by idiotype IgG2 protein levels and increased survival compared to untreated controls (P < 0.05) in the 5TGM1 mice after injection of 5TGM1 MMSC. Conclusion: Over-expression of RARa2 induces drug resistance by activating the drug efflux pump gene ABCC3 through activation of the Wnt and Hedgehog pathways, while inhibition of RARα2 decreases drug resistance. We also provide a possible strategy to eliminate MMSC by targeting RARa2 and/or its downstream targets, such as the Wnt and Hedgehog pathways. Disclosures: No relevant conflicts of interest to declare.

New Mechanistic Insight on the PIM-1 Kinase Inhibitor AZD1208 Using Multidrug Resistant Human Erythroleukemia Cell Lines and Molecular Docking Simulations

2019 ◽  
Vol 19 (11) ◽  
pp. 914-926 ◽  
Author(s):  
Maiara Bernardes Marques ◽  
Michael González-Durruthy ◽  
Bruna Félix da Silva Nornberg ◽  
Bruno Rodrigues Oliveira ◽  
Daniela Volcan Almeida ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Binding Site ◽  
Cell Lines ◽  
Chemotherapeutic Agents ◽  
Atp Binding ◽  
Human Leukemia ◽  
Atp Binding Site ◽  
Mechanistic Insight ◽  
Multiple Drugs

Background:PIM-1 is a kinase which has been related to the oncogenic processes like cell survival, proliferation, and multidrug resistance (MDR). This kinase is known for its ability to phosphorylate the main extrusion pump (ABCB1) related to the MDR phenotype.Objective:In the present work, we tested a new mechanistic insight on the AZD1208 (PIM-1 specific inhibitor) under interaction with chemotherapy agents such as Daunorubicin (DNR) and Vincristine (VCR).Materials and Methods:In order to verify a potential cytotoxic effect based on pharmacological synergism, two MDR cell lines were used: Lucena (resistant to VCR) and FEPS (resistant to DNR), both derived from the K562 non-MDR cell line, by MTT analyses. The activity of Pgp was ascertained by measuring accumulation and the directional flux of Rh123. Furthermore, we performed a molecular docking simulation to delve into the molecular mechanism of PIM-1 alone, and combined with chemotherapeutic agents (VCR and DNR).Results:Our in vitro results have shown that AZD1208 alone decreases cell viability of MDR cells. However, co-exposure of AZD1208 and DNR or VCR reverses this effect. When we analyzed the ABCB1 activity AZD1208 alone was not able to affect the pump extrusion. Differently, co-exposure of AZD1208 and DNR or VCR impaired ABCB1 activity, which could be explained by compensatory expression of abcb1 or other extrusion pumps not analyzed here. Docking analysis showed that AZD1208 is capable of performing hydrophobic interactions with PIM-1 ATP- binding-site residues with stronger interaction-based negative free energy (FEB, kcal/mol) than the ATP itself, mimicking an ATP-competitive inhibitory pattern of interaction. On the same way, VCR and DNR may theoretically interact at the same biophysical environment of AZD1208 and also compete with ATP by the PIM-1 active site. These evidences suggest that AZD1208 may induce pharmacodynamic interaction with VCR and DNR, weakening its cytotoxic potential in the ATP-binding site from PIM-1 observed in the in vitro experiments.Conclusion:Finally, the current results could have a pre-clinical relevance potential in the rational polypharmacology strategies to prevent multiple-drugs resistance in human leukemia cancer therapy.

scholarly journals Implementation of the NCI-60 Human Tumor Cell Line Panel to Screen 2260 Cancer Drug Combinations to Generate >3 Million Data Points Used to Populate a Large Matrix of Anti-Neoplastic Agent Combinations (ALMANAC) Database

2018 ◽  
Vol 24 (3) ◽  
pp. 242-263 ◽  
Author(s):  
David A. Close ◽  
Allen Xinwei Wang ◽  
Stanton J. Kochanek ◽  
Tongying Shun ◽  
Julie L. Eiseman ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Growth Inhibition ◽  
Cell Line ◽  
Cell Lines ◽  
Cancer Cell ◽  
Cancer Cell Lines ◽  
Cancer Drug ◽  
Large Matrix ◽  
Data Points

Animal and clinical studies demonstrate that cancer drug combinations (DCs) are more effective than single agents. However, it is difficult to predict which DCs will be more efficacious than individual drugs. Systematic DC high-throughput screening (HTS) of 100 approved drugs in the National Cancer Institute’s panel of 60 cancer cell lines (NCI-60) produced data to help select DCs for further consideration. We miniaturized growth inhibition assays into 384-well format, increased the fetal bovine serum amount to 10%, lengthened compound exposure to 72 h, and used a homogeneous detection reagent. We determined the growth inhibition 50% values of individual drugs across 60 cell lines, selected drug concentrations for 4 × 4 DC matrices (DCMs), created DCM master and replica daughter plate sets, implemented the HTS, quality control reviewed the data, and analyzed the results. A total of 2620 DCMs were screened in 60 cancer cell lines to generate 3.04 million data points for the NCI ALMANAC (A Large Matrix of Anti-Neoplastic Agent Combinations) database. We confirmed in vitro a synergistic drug interaction flagged in the DC HTS between the vinca-alkaloid microtubule assembly inhibitor vinorelbine (Navelbine) tartrate and the epidermal growth factor-receptor tyrosine kinase inhibitor gefitinib (Iressa) in the SK-MEL-5 melanoma cell line. Seventy-five percent of the DCs examined in the screen are not currently in the clinical trials database. Selected synergistic drug interactions flagged in the DC HTS described herein were subsequently confirmed by the NCI in vitro, evaluated mechanistically, and were shown to have greater than single-agent efficacy in mouse xenograft human cancer models. Enrollment is open for two clinical trials for DCs that were identified in the DC HTS. The NCI ALMANAC database therefore constitutes a valuable resource for selecting promising DCs for confirmation, mechanistic studies, and clinical translation.

Irinotecan Resistance – In Search of New Markers in CRC.

2021 ◽  
Author(s):  
Jakub Kryczka ◽  
Joanna Boncela
Keyword(s):  
Drug Resistance ◽  
Cell Lines ◽  
Expression Profiles ◽  
Resistance Mechanism ◽  
Interaction Network ◽  
In Vitro Study ◽  
Cancer Drug ◽  
New Genes

Abstract Colorectal cancer (CRC) is one of the most prominent causes of cancer death worldwide. Chemotherapeutic regimens consisting of different drugs combinations such as 5-fluorouracil, and oxaliplatin (FOLFOX) or irinotecan (FOLFIRI) have been proven successful in the treatment of CRC. However, chemotherapy often leads to the acquisition of cancer drug resistance followed by metastasis and in the aftermath therapeutic failure. The molecular mechanism responsible for drug resistance is still unclear. The systemic search for new biomarkers of this phenomenon may identify new genes and pathways. To understand the drug resistance mechanism in CRC, the in vitro study based on the molecular analysis of drug-sensitive cells lines vs drug-resistant cells lines has been used. In our study to bridge the gap between in vitro and in vivo study, we compared the expression profiles of cell lines and patient samples from the publicly available database to select the new candidate genes for irinotecan resistance. Using The Gene Expression Omnibus (GEO) database of CRC cell lines (HT29, HTC116, LoVo, and their respective irinotecan-resistant variants) and patient samples (GSE42387, GSE62080, and GSE18105) we compared the changes in the mRNA expression profile of the main genes involved in irinotecan body’s processing, such as transport out of the cells and metabolism. Furthermore, using a protein-protein interaction network of differently expressed genes between FOLFIRI resistant and sensitive CRC patients, we have selected top networking proteins (upregulated: NDUFA2, SDHD, LSM5, DCAF4, and COX10, downregulated: RBM8A, TIMP1, QKI, TGOLN2, and PTGS2). Our analysis provided several potential irinotecan resistance markers, previously not described as such.

The Design and Synthesis of Novel Phenothiazine Derivatives as Potential Cytotoxic Agents

2019 ◽  
Vol 17 (1) ◽  
pp. 57-67
Author(s):  
Yepeng Luan ◽  
Jinyi Liu ◽  
Jianjun Gao ◽  
Jinhua Wang
Keyword(s):  
Cell Lines ◽  
High Efficiency ◽  
Human Cancer ◽  
Human Tumor ◽  
Cytotoxic Agents ◽  
Cancer Drug ◽  
Human Cancer Cell Lines ◽  
Incidence And Mortality ◽  
Anti Cancer

Background: Cancer incidence and mortality have been increasing and cancer is still the leading cause of death all over the world. Despite the enormous progress in cancer treatment, many patients died of ineffective chemotherapy and drug resistance. Therefore, the design and development of anti-cancer drugs with high efficiency and low toxicity is still one of the most challenging tasks. Tricyclic heterocycles, such as phenothiazine, are always important sources of scaffolds for anti-cancer drug discovery. Methods: In this work, ten new urea-containing derivatives of phenothiazine coupled with different kinds of amine motifs at the endpoint through a three carbon long spacer were designed and synthesized. The structures of the synthesized compounds were elucidated and confirmed by 1H NMR and HRMS. All the synthesized compounds were tested for their antitumor activity in vitro against the proliferation of PC-3 cells, and the compounds with best potency entered further cytotoxicity evaluations against other 22 human tumor cell lines. Mechanism was also studied. Results: From all data, it showed that among all 10 target compounds, TTi-2 showed the best effect in inhibiting the proliferation of 23 human cancer cell lines while TTi-2 without obvious inhibitory effect on normal cell. Furthermore, our results also showed that TTi-2 could inhibit migration, invasion and colony formation of MDA-MB-231 cells. Finally, TTi-2 can induce arrest of cell cycle at G0/G1 phase and cell apoptosis by activating the caspase 3 activity. Conclusion: All these results suggested that TTi-2 might be used as a promising lead compound for anticancer drug development.

JS-K, a GST-Activated Nitric Oxide Generator, Induces Apoptosis and Overcomes In Vitro Drug Resistance in Multiple Myeloma Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1593-1593
Author(s):  
Tanyel Kiziltepe ◽  
Kenji Ishitsuka ◽  
Teru Hideshima ◽  
Noopur Raje ◽  
Norihiko Shiraishi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Multiple Myeloma ◽  
Drug Resistance ◽  
Tumor Cells ◽  
Cell Lines ◽  
Biological Effects ◽  
Treatment Modalities ◽  
Cancer Drug ◽  
Induced Apoptosis

Abstract Multiple myeloma (MM) is currently an incurable hematological malignancy. A major reason for the failure of currently existing therapies is the chemotherapeutic resistance acquired by the MM cells upon treatment. Overexpression of glutathione S-transferases (GST) has been shown as one possible mechanism of anti-cancer drug resistance in a broad spectrum of tumor cells. JS-K (O2-(2,4-Dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate) belongs to a class of pro-drugs which are designed to release nitric oxide (NO) on reaction with GST. JS-K can possibly turn GST overexpression to the tumor’s disadvantage by (1) consuming intracellular GSH and preventing drug inactivation; and (2) by exposing tumor cells to high intracellular concentrations of NO. JS-K has potent in vitro and in vivo anti-leukemic activity. The purpose of the present study is to examine the biological effects of JS-K on human MM cells. We demonstrate that JS-K has significant in vitro cytotoxicity on MM cell lines, with an IC50 of 0.3-2 mM at 48 hours. JS-K also induces cytotoxicity on cell lines that are resistant to conventional chemotherapy (i.e., MM1R, RPMI-Dox40, RPMI-LR5, RPMI-MR20). Importantly, no cytotoxic effects of JS-K were detected on peripheral blood mononuclear cells (PBMNC) obtained from healthy volunteers at these doses. Moreover, JS-K could overcome the survival and growth advantages conferred by interleukin-6 (IL-6) and insulin-like growth factor-1 (IGF-1), or by adherence of MM cells to bone marrow stromal cells (BMSC). JS-K caused a transient G2/M arrest followed by apoptosis, as determined by flow cytometric analysis using PI, Annexin V and Apo2.7 staining. JS-K-induced apoptosis was associated with caspase 8, 7, 9 and 3 activation. Interestingly, Fas was upregulated by JS-K, suggesting the involvement of death receptor pathway in induction of apoptosis. JS-K also triggered Mcl-1 cleavage and Bcl-2 phosphorylation, suggesting the involvement of mitochondrial pathway. In addition, apoptosis inducing factor (AIF), endonuclease G (EndoG) and cytochrome c were released into the cytosol during apoptosis. Taken together, these findings suggest the involvement of both intrinsic and extrinsic apoptotic pathways in JS-K-induced apoptosis in MM cells. In summary, our studies demonstrate that JS-K induces apoptosis and overcomes in vitro drug resistance in MM cells. Therefore, JS-K is a novel compound which carries significant potential to be included in the repertoire of existing treatment modalities for MM. Ongoing studies are delineating the mechanism of action of JS-K to provide the preclinical rationale for combination therapies to overcome drug resistance and improve patient outcome.

iMYC: Proof-of-concept study of ibrutinib in c-MYC and HER2 amplified oesophagogastric carcinoma.

2017 ◽  
Vol 35 (4_suppl) ◽  
pp. TPS221-TPS221
Author(s):  
Michael Davidson ◽  
Irene Yu-Shing Chong ◽  
David Cunningham ◽  
Lauren Aronson ◽  
Hanna Bryant ◽  
...  
Keyword(s):  
Cell Lines ◽  
Human Cancer ◽  
Locally Advanced ◽  
Imaging Biomarker ◽  
Cancer Drug ◽  
Lethal Gene ◽  
Her2 Amplification ◽  
Open Label ◽  
Biomarker Analysis

TPS221 Background: The MYC proto-oncogene is among the most frequently dysregulated genes in human cancer and is amplified in 10-30% of oesophagogastric (OG) cancers. Such genes which code for transcription factors are challenging to target directly with small molecule inhibitors or monoclonal antibodies. High-throughput siRNA screening of OG cell lines has found silencing of Bruton’s tyrosine kinase (BTK) to result in selective lethality in the presence of MYC amplification. Sensitivity to the orally available BTK inhibitor ibrutinib has been confirmed in-vitro in MYC, HER2 and co-amplified OG cancer cell lines (Chong, Ann Onc 2014), suggesting it may be a potentially effective therapeutic strategy in both MYC and HER2 amplified OG cancer. Methods: i MYC is an open label, phase II non-randomised study to assess the efficacy of ibrutinib in advanced pre-treated OG cancer. A novel FISH assay for tumour MYC amplification has been developed and pts are pre-screened for MYC and HER2 amplification. Eligibility includes metastatic or locally advanced inoperable OG cancer (SCC or adeno), MYC (ratio >2.5) and/or HER2 (ratio>2) amplification, progression after at least 1 prior line of chemotherapy +/- trastuzumab for advanced disease, PS 0-2 and no history of significant cardiovascular or bleeding disorders. Of the first 9 pts, at least 4 will demonstrate MYC amplification and remaining 5 will show either MYC or HER2 amplification, or co-amplification of both. Pts will be treated with ibrutinib monotherapy until progression or unacceptable toxicity. A Simon 2 stage design will be used for the primary endpoint of response rate, with interim analysis after 9 pts and maximum recruitment to 17 pts. Secondary endpoints include PFS, OS and exploratory translational and imaging biomarker analysis. Mandatory biopsy will be obtained at baseline and optional biopsies will be undertaken at day 10-14, week 8 and progression. The trial represents the first attempt at targeting MYC amplification via synthetic lethal gene interactions in OG cancer through the novel application of an existing anti-cancer drug. As of September 2016, 61 patients have consented for pre-screening, 19 completed MYC analysis and first patient has started treatment. Clinical trial information: 02884453.

Increased susceptibility of a triclabendazole (TCBZ)-resistant isolate of Fasciola hepatica to TCBZ following co-incubation in vitro with the P-glycoprotein inhibitor, R(+)-verapamil

Parasitology ◽  
2013 ◽  
Vol 140 (10) ◽  
pp. 1287-1303 ◽  
Author(s):  
M. MEANEY ◽  
J. SAVAGE ◽  
G. P. BRENNAN ◽  
E. HOEY ◽  
A. TRUDGETT ◽  
...  
Keyword(s):  
Fasciola Hepatica ◽  
Efflux Pump ◽  
Morphological Changes ◽  
Resistant Isolate ◽  
Drug Efflux ◽  
P Glycoprotein ◽  
Efflux Pump Inhibition ◽  
Inactivity Time ◽  
Drug Efflux Pumps

SUMMARYA study was carried out to investigate whether the action of triclabendazole sulphoxide (TCBZ.SO) against the liver fluke, Fasciola hepatica is altered by inhibition of P-glycoprotein (Pgp)-linked drug efflux pumps. The Oberon TCBZ-resistant and Cullompton TCBZ-susceptible fluke isolates were used for this in vitro study and the Pgp inhibitor selected was R(+)-verapamil [R(+)-VPL]. For experiments with the Oberon isolate, flukes were incubated for 24 h with either R(+)-VPL (1×10−4m) on its own, TCBZ.SO (15 μg mL−1) alone, a combination of R(+)-VPL (1×10−4m) plus TCBZ.SO (15 μg mL−1), TCBZ.SO (50 μg mL−1) on its own, or a combination of TCBZ.SO (50 μg mL−1) plus R(+)-VPL (1×10−4m). They were also incubated in TCBZ.SO (50 μg mL−1) alone or in combination with R(+)-VPL (1×10−4m) until they became inactive; and in TCBZ.SO (50 μg mL−1) alone for a time to match that of the combination inactivity time. Flukes from the Cullompton isolate were treated with either TCBZ.SO (50 μg mL−1) alone or in combination with R(+)-VPL (1×10−4m) until they became inactive, or with TCBZ.SO (50 μg mL−1) alone time-matched to the combination inactivity time. Morphological changes resulting from drug treatment and following Pgp inhibition were assessed by means of scanning electron microscopy. Incubation in R(+)-VPL alone had a minimal effect on either isolate. TCBZ.SO treatment had a relatively greater impact on the TCBZ-susceptible Cullompton isolate. When R(+)-VPL was combined with TCBZ.SO in the incubation medium, however, the surface disruption to both isolates was more severe than that seen after TCBZ.SO treatment alone; also, the time taken to reach inactivity was shorter. More significantly, though, the potentiation of drug activity was greater in the Oberon isolate; also, it was more distinct at the higher concentration of TCBZ.SO. So, the Oberon isolate appears to be particularly sensitive to efflux pump inhibition. The results of this study suggest that enhanced drug efflux in the Oberon isolate may be involved in the mechanism of resistance to TCBZ.

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