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Di Desidero T, Orlandi P, Gentile D, Bocci G. Effects of Pazopanib Monotherapy vs. Pazopanib and Topotecan Combination on Anaplastic Thyroid Cancer Cells. Front Oncol 2019; 9:1202. [PMID: 31799182 PMCID: PMC6863333 DOI: 10.3389/fonc.2019.01202] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 10/22/2019] [Indexed: 12/22/2022] Open
Abstract
The purpose of this study was to examine pazopanib/topotecan combination activity vs. pazopanib monotherapy on anaplastic thyroid cancer (ATC) cells. Proliferation analyses were performed on ATC cell lines administered for 72 h with pazopanib and topotecan alone and to their simultaneous combination. Pazopanib and topotecan produced a strong synergism on ATC cells, calculated by the combination index, increasing the intracellular concentrations of topotecan lactone measured by high-performance liquid chromatography. Furthermore, a significantly decrease of the gene expression of ATP-binding cassette transporter G2 (ABCG-2), vascular endothelial growth factor (VEGF), hypoxia-inducible factor-1α (HIF-1α), and colony stimulating factor-1 (CSF-1) was presented in combination-treated ATC cells by real time PCR tests. In summary, the simultaneous association of pazopanib and topotecan established a highly synergistic ATC antiproliferative effect, suggesting a new possibility to translate this schedule into clinical trials.
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Affiliation(s)
- Teresa Di Desidero
- Dipartimento di Medicina Clinica e Sperimentale, University of Pisa, Pisa, Italy
| | - Paola Orlandi
- Dipartimento di Medicina Clinica e Sperimentale, University of Pisa, Pisa, Italy
| | - Daniela Gentile
- Dipartimento di Medicina Clinica e Sperimentale, University of Pisa, Pisa, Italy
| | - Guido Bocci
- Dipartimento di Medicina Clinica e Sperimentale, University of Pisa, Pisa, Italy
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Sinha BK, Perera L, Cannon RE. Reversal of drug resistance by JS-K and nitric oxide in ABCB1- and ABCG2-expressing multi-drug resistant human tumor cells. Biomed Pharmacother 2019; 120:109468. [PMID: 31605952 DOI: 10.1016/j.biopha.2019.109468] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/04/2019] [Accepted: 09/16/2019] [Indexed: 11/26/2022] Open
Abstract
Development of resistance to chemotherapy drugs is a significant problem in treating human malignancies in the clinic. Overexpression of ABC transporter proteins, including P-170 glycoprotein (P-gp), and breast cancer resistance protein (BCRP, ABCG2) have been implicated in this multi-drug resistance (MDR). These ABC transporters are ATP-dependent efflux proteins. We have recently shown that nitric oxide (NO) inhibits the ATPase activities of P-gp, resulting in a significant enhancement of drug accumulation and the reversal of multi-drug resistance in NCI/ADR-RES cells, a P-gp-overexpressing human MDR cell line. In this study, we used [O2-(2,4-dinitrophenyl)-1-[(4-ethoxycarbonyl)-piperazin-1 yl]-diazene-1-ium-1-2-diolate] (JS-K), a tumor-specific NO-donor to study the reversal of drug resistance in both P-gp- and BCRP-overexpressing human tumor cells. We report here that while JS-K was extremely effective in reversing adriamycin resistance in the P-gp-overexpressing tumor cells (NCI/ADR-RES); it was significantly resistant to BCRP-overexpressing (MCF-7/MX) tumor cells, suggesting that JS-K may be a substrate for BCRP. Using another NO-donor (DETNO), we show that NO directly inhibits the ATP activities of BCRP, inducing significant increases in the accumulations of both Hoechst 33342 dye and topotecan, substrates for BCRP. Furthermore, NO treatment significantly reversed topotecan and mitoxantrone resistance to MCF-7/MX tumor cells. Molecular docking studies indicated that while DETNO and JS-K bind to ATP binding site in both ABC proteins, binding score was significantly reduced, compared to the ATP binding. Our results indicate that appropriately designed NO donors may find success in reversing multidrug resistance in the clinic.
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Affiliation(s)
- Birandra K Sinha
- Laboratory of Immunity, Inflammation, Disease Laboratory, National Institutes of Environmental Health Sciences, NIH, Research Triangle Park, NC, USA.
| | - Lalith Perera
- Laboratory of Genome Integrity and Structural Biology, National Institutes of Environmental Health Sciences, NIH, Research Triangle Park, NC, USA
| | - Ronald E Cannon
- Laboratory of Toxicology and Toxicokinetic, National Cancer Institute at National Institute of Environmental Health Sciences, National Institutes of Environmental Health Sciences, NIH, Research Triangle Park, NC, USA
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Mitchell AB, Vasilyeva A, Gajjar A, Santana VM, Stewart CF. Determining success rates of the current pharmacokinetically guided dosing approach of topotecan in pediatric oncology patients. Pediatr Blood Cancer 2019; 66:e27578. [PMID: 30548417 PMCID: PMC6386591 DOI: 10.1002/pbc.27578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/07/2018] [Accepted: 11/13/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND Topotecan is a chemotherapeutic agent that is active against many pediatric tumors. Although its effect is related to systemic exposure, the interpatient variability in systemic clearance makes it challenging to achieve desired topotecan targets. This study aims to evaluate the success of the pharmacokinetically (PK) guided dosing process, which was used to achieve a target topotecan area under the concentration-time curve (AUC). METHODS Patients received an empiric topotecan dosage on the first day; the topotecan lactone AUC was determined, and based upon these values the topotecan dosage was adjusted. The success rates of both the empiric and PK-guided strategies were calculated. Patient-specific covariates were collected to explain variability observed in the empiric and PK-guided results. A simulation study was performed to assess the differences in cumulative topotecan dosage and systemic exposure between a PK-guided and standard dosing approach. RESULTS Data were collected from nine clinical trials open from 1996 to 2016 (n = 232 patients). The empiric dosing success rate was 35.5%, while the PK-guided rate was 64.4%. A difference in mean serum creatinine was observed between successful empiric studies and those above the AUC target. Compared to a standard dosing approach, the PK-guided group had a higher average cumulative dosage and systemic exposure. CONCLUSION The low empiric dosing success rate indicates that additional studies are needed to refine the initial topotecan dosage. The role of renal function, measured as serum creatinine, remains to be elucidated. However, the PK-guided targeting success rate highlighted the need to account for variable topotecan systemic clearance.
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Affiliation(s)
- Anna Birg Mitchell
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, Memphis, Tennessee
| | - Aksana Vasilyeva
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, Memphis, Tennessee
| | - Amar Gajjar
- Department of Oncology, St. Jude Children’s Research Hospital, Memphis, Tennessee
| | - Victor M. Santana
- Department of Oncology, St. Jude Children’s Research Hospital, Memphis, Tennessee
| | - Clinton F. Stewart
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, Memphis, Tennessee
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Di Desidero T, Xu P, Man S, Bocci G, Kerbel RS. Potent efficacy of metronomic topotecan and pazopanib combination therapy in preclinical models of primary or late stage metastatic triple-negative breast cancer. Oncotarget 2015; 6:42396-410. [PMID: 26623560 PMCID: PMC4767441 DOI: 10.18632/oncotarget.6377] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/16/2015] [Indexed: 12/21/2022] Open
Abstract
Metronomic chemotherapy has shown promising activity in numerous preclinical studies and also some phase II clinical studies involving various tumor types, and is currently undergoing phase III trial evaluation. Triple-negative breast cancer (TNBC) is an aggressive histological subtype with limited treatment options and very poor prognosis following progression after standard chemotherapeutic regimens. Herein, we evaluated the potential therapeutic impact and molecular mechanisms of topotecan administered in a continuous low-dose metronomic (LDM) manner, alone or in concurrent combination with pazopanib, an antiangiogenic tyrosine kinase inhibitor (TKI), in a triple-negative, primary and metastatic breast cancer orthotopic model; potential molecular mechanisms of efficacy were also studied, especially the impact of hypoxic conditions. The combination of metronomic topotecan and pazopanib significantly enhanced antitumor activity compared to monotherapy with either drug and prolonged survival, even in the advanced metastatic survival setting, with a marked decrease in tumor vascularity, proliferative index, and the induction of apoptosis. Significant changes in tumor angiogenesis, cancer cell proliferation, apoptosis, HIF1α levels, HIF-1 target genes and ABCG2 were found both in vitro and in tumor tissue. Notably, the pazopanib and metronomic topotecan combination treatment inhibited expression of HIF1α and ABCG2 genes in cells grown under hypoxic conditions, and this was associated with an increased intracellular concentration of the active form of topotecan. Our results suggest a potential novel therapeutic option for the treatment of metastatic triple-negative breast cancer patients.
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Affiliation(s)
- Teresa Di Desidero
- Biologic Sciences Platform, Sunnybrook Research Institute, Toronto, Canada
- Divisione di Farmacologia, Dipartimento di Medicina Clinica e Sperimentale, University of Pisa, Pisa, Italy
| | - Ping Xu
- Biologic Sciences Platform, Sunnybrook Research Institute, Toronto, Canada
| | - Shan Man
- Biologic Sciences Platform, Sunnybrook Research Institute, Toronto, Canada
| | - Guido Bocci
- Divisione di Farmacologia, Dipartimento di Medicina Clinica e Sperimentale, University of Pisa, Pisa, Italy
| | - Robert S. Kerbel
- Biologic Sciences Platform, Sunnybrook Research Institute, Toronto, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
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5
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Influence of sample handling conditions on drug partitioning in blood: a major problem in PK studies? Bioanalysis 2015; 7:2973-6. [PMID: 26616634 DOI: 10.4155/bio.15.209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Analysis of acquired resistance to metronomic oral topotecan chemotherapy plus pazopanib after prolonged preclinical potent responsiveness in advanced ovarian cancer. Angiogenesis 2014; 17:661-73. [PMID: 24569856 DOI: 10.1007/s10456-014-9422-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 01/07/2014] [Indexed: 02/03/2023]
Abstract
An alternative or follow-up adjunct to conventional maximum tolerated dose (MTD) chemotherapy now in advanced phase III clinical trial assessment is metronomic chemotherapy--the close regular administration of low doses of drug with no prolonged breaks. A number of preclinical studies have shown metronomic chemotherapy can cause long term survival of mice with advanced cancer, including metastatic disease, in the absence of overt toxicity, especially when combined with targeted antiangiogenic drugs. However, similar to MTD chemotherapy acquired resistance eventually develops, the basis of which is unknown. Using a preclinical model of advanced human ovarian (SKOV-3-13) cancer in SCID mice, we show that acquired resistance can develop after terminating prolonged (over 3 months) successful therapy utilizing daily oral metronomic topotecan plus pazopanib, an oral antiangiogenic tyrosine kinase inhibitor (TKI). Two resistant sublines were isolated from a single mouse, one from a solid tumor (called KH092-7SD, referred to as 7SD) and another from ascites tumor cells (called KH092-7AS, referred to as 7AS). Using these sublines we show acquired resistance to the combination treatment is due to tumor cell alterations that confer relative refractoriness to topotecan. The resistant phenotype is heritable, associated with reduced cellular uptake of topotecan and could not be reversed by switching to MTD topotecan or to another topoisomerase-1 inhibitor, CPT-11, given either in a metronomic or MTD manner nor switching to another antiangiogenic drug, e.g. the anti-VEGFR-2 antibody, DC101, or another TKI, sunitinib. Thus, in this case cross resistance seems to exist between MTD and metronomic topotecan, the basis of which is unknown. However, gene expression profiling revealed several potential genes that are stably upregulated in the resistant lines, that previously have been implicated in resistance to various chemotherapy drugs, and which, therefore, may contribute to the drug resistant phenotype.
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7
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Ye L, Shi J, Wan S, Yang X, Wang Y, Zhang J, Zheng D, Liu Z. Development and validation of a liquid chromatography-tandem mass spectrometry method for topotecan determination in beagle dog plasma and its application in a bioequivalence study. Biomed Chromatogr 2013; 27:1532-9. [PMID: 23788247 DOI: 10.1002/bmc.2956] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 04/12/2013] [Accepted: 05/07/2013] [Indexed: 01/15/2023]
Abstract
Topotecan (TPT) is an important anti-cancer drug that inhibits topoisomerase I. A sensitive and robust liquid chromatography-tandem mass spectrometry (LC-MS/MS) method that potentially determines TPT in beagle dog plasma is needed for a bioequivalence study of TPT formulations. We developed and validated LC-MS/MS to evaluate TPT in beagle dog plasma in terms of specificity, linearity, precision, accuracy, stability, extraction recovery and matrix effect. Plasma samples were treated with an Ostro(TM) sorbent plate (a robust and effective tool) to eliminate phospholipids and proteins before analysis. TPT and camptothecin (internal standard) were separated on an Acquity UPLC BEH C18 column (1.7 µm, 2.1 × 50 mm) with 0.1% formic acid and methanol as the mobile phase at a flow rate of 0.25 mL/min. TPT was analyzed using positive ion electrospray ionization in multiple-reaction monitoring mode. The obtained lower limit of quantitation was 1 ng/mL (signal-to-noise ratio > 10). The standard calibration curve for TPT was linear (correlation coefficient > 0.99) at the concentration range of 1-400 ng/mL. The intra-day and inter-day precision, accuracy, stability, extraction recovery and matrix effect of TPT were within the acceptable limits. The validated method was successfully applied in a bioequivalence study of TPT in healthy beagle dogs.
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Affiliation(s)
- Ling Ye
- Department of Pharmaceutics, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China
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Hahnfeldt P, Hlatky L, Klement GL. Center of cancer systems biology second annual workshop--tumor metronomics: timing and dose level dynamics. Cancer Res 2013; 73:2949-54. [PMID: 23492368 DOI: 10.1158/0008-5472.can-12-3807] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Metronomic chemotherapy, the delivery of doses in a low, regular manner so as to avoid toxic side effects, was introduced over 12 years ago in the face of substantial clinical and preclinical evidence supporting its tumor-suppressive capability. It constituted a marked departure from the classic maximum-tolerated dose (MTD) strategy, which, given its goal of rapid eradication, uses dosing sufficiently intense to require rest periods between cycles to limit toxicity. Even so, upfront tumor eradication is frequently not achieved with MTD, whereupon a de facto goal of longer-term tumor control is often pursued. As metronomic dosing has shown tumor control capability, even for cancers that have become resistant to the same drug delivered under MTD, the question arises whether it may be a preferable alternative dosing approach from the outset. To date, however, our knowledge of the coupled dynamics underlying metronomic dosing is neither sufficiently well developed nor widely enough disseminated to establish its actual potential. Meeting organizers thus felt the time was right, armed with new quantitative approaches, to call a workshop on "Tumor Metronomics: Timing and Dose Level Dynamics" to explore prospects for gaining a deeper, systems-level appreciation of the metronomics concept. The workshop proved to be a forum in which experts from the clinical, biologic, mathematical, and computational realms could work together to clarify the principles and underpinnings of metronomics. Among other things, the need for significant shifts in thinking regarding endpoints to be used as clinical standards of therapeutic progress was recognized.
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Affiliation(s)
- Philip Hahnfeldt
- Center of Cancer Systems Biology, Steward St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, MA, USA.
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9
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Li N, Han X, Yang J, Gui L, Song Y, Du P, Shi Y. Absolute bioavailability studies of a new oral topotecan formulation in Chinese patients using UHPLC–MS/MS. J Pharm Biomed Anal 2013; 76:252-6. [PMID: 23354352 DOI: 10.1016/j.jpba.2012.12.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 12/28/2012] [Accepted: 12/30/2012] [Indexed: 10/27/2022]
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Crowe A, Keelan JA. Development of a Model for Functional Studies of ABCG2 (Breast Cancer Resistance Protein) Efflux Employing a Standard BeWo Clone (B24). Assay Drug Dev Technol 2012; 10:476-84. [DOI: 10.1089/adt.2011.441] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Affiliation(s)
- Andrew Crowe
- School of Pharmacy and Curtin Health Innovation Research Institute, Curtin University, Perth, Australia
| | - Jeffrey A. Keelan
- School of Women's and Infants Health, University of Western Australia, Crawley, Australia
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11
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Electroencephalographic recovery, hypnotic emergence, and the effects of metabolite after continuous infusions of a rapidly metabolized etomidate analog in rats. Anesthesiology 2012; 116:1057-65. [PMID: 22417966 DOI: 10.1097/aln.0b013e3182515403] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Methoxycarbonyl etomidate is an ultrarapidly metabolized etomidate analog. It is metabolized to methoxycarbonyl etomidate carboxylic acid (MOC-ECA), which has a hypnotic potency that is 350-fold less than that of methoxycarbonyl etomidate. The authors explored the relationships between methoxycarbonyl etomidate infusion duration, recovery time, metabolite concentrations in blood and cerebrospinal fluid (CSF), and methoxycarbonyl etomidate metabolism in brain tissue and CSF to test the hypothesis that rapid metabolism of methoxycarbonyl etomidate may lead to sufficient accumulation of MOC-ECA in the brain to produce a pharmacologic effect. METHODS A closed-loop system with burst suppression ratio feedback was used to administer methoxycarbonyl etomidate infusions of varying durations to rats. After infusion, recovery of the electroencephalogram and righting reflexes were assessed. MOC-ECA concentrations were measured in blood and CSF during and after methoxycarbonyl etomidate infusion, and the in vitro half-life of methoxycarbonyl etomidate was determined in rat brain tissue and CSF. RESULTS Upon termination of continuous methoxycarbonyl etomidate infusions, the burst suppression ratio recovered in a biexponential manner with fast and slow components having time constants that differed by more than 100-fold and amplitudes that varied inversely with infusion duration. MOC-ECA concentrations reached hypnotic concentrations in the CSF with prolonged methoxycarbonyl etomidate infusion and then decreased during a period of several hours after infusion termination. The metabolic half-life of methoxycarbonyl etomidate in brain tissue and CSF was 11 and 20 min, respectively. CONCLUSION In rats, methoxycarbonyl etomidate metabolism is sufficiently fast to produce pharmacologically active MOC-ECA concentrations in the brain with prolonged methoxycarbonyl etomidate infusion.
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Bączek T, Konieczna L, Belka M, Maciejka-Kapuścińska L, Wiśniewski J, Niedźwiecki M, Balcerska A, Adamkiewicz-Drożyńska E, Wachowiak J. Topotecan exposure estimation in pediatric acute myeloid leukemia supported by LC-MS-based drug monitoring and pharmacokinetic analysis. J Pharm Biomed Anal 2012; 70:330-6. [PMID: 22658903 DOI: 10.1016/j.jpba.2012.05.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/24/2012] [Accepted: 05/08/2012] [Indexed: 10/28/2022]
Abstract
Individualization of the topotecan dosing can reduce inter-patient variability, toxicity, and at the same time increases chemotherapy efficacy. Topotecan dosing based on simultaneous drug monitoring and pharmacokinetic analysis can yield more accurate and precise estimation of the topotecan systemic exposure than that attainable with the fixed dosing approach. Therefore, a combined approach could provide a tool assisting the clinicians in individualization of the topotecan dosing. The aim of the study was to estimate the topotecan exposure in pediatric patients with acute myeloid leukemia (AML) based on the plasma concentration-time data and using the pharmacokinetic analysis. The primary goal was achieve the correct estimation of the target plasma area against the topotecan concentration-time curve (AUC) in a 5 day course of cladribine followed by monitored topotecan in pediatric patients with recurrent/refractory AML. A sensitive and selective reversed-phase liquid chromatographic-mass spectrometry (LC-MS) assay was developed to quantify total topotecan in the human plasma samples. This method, with its lower quantification limit of 1 ng/ml, was validated over a linear range of 1-150 ng/ml. Under the proposed approach, the topotecan dosing was selected so as to achieve the final AUC value of 140±20 ng/ml h. The presented analytical and pharmacokinetic data demonstrate that the proposed approach can be a practical, useful, efficient, and accurate tool for individualizing the topotecan dosing in children with AML.
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Affiliation(s)
- Tomasz Bączek
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, Gen. J. Hallera 107, 80-416 Gdańsk, Poland.
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13
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Kasow KA, Stewart CF, Barfield RC, Wright NL, Li C, Srivastava DK, Leung W, Horwitz EM, Bowman LC, Handgretinger R, Hale GA. A phase I/II study of CY and topotecan in patients with high-risk malignancies undergoing autologous hematopoietic cell transplantation: the St Jude long-term follow-up. Bone Marrow Transplant 2012; 47:1448-54. [PMID: 22426752 DOI: 10.1038/bmt.2012.51] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Fifty-eight consecutive children with high-risk malignancies were treated with CY, and targeted topotecan followed by autologous hematopoietic cell transplantation (AHCT) in a phase I/II Institutional Review Board-approved study. Twelve participants enrolled in phase I; 5 received dose level 1 of topotecan 3 mg/m(2) per day, with subsequent doses targeted to total systemic exposure of 100±20 ng h/mL and CY 750 mg/m(2) per day. Seven participants received dose level 2. CY dose escalation to 1 g/m(2) per day was considered excessively toxic; one died from irreversible veno-occlusive disease and two experienced reversible hepatotoxicity. These adverse events halted further dose escalation. A total of 46 participants were enrolled in phase II; results are on the 51 participants who received therapy at dose level 1, the maximum tolerated dose. Diagnoses included neuroblastoma (26), sarcoma (9), lymphoma (8), brain tumors (5), Wilms (2) and retinoblastoma (1). Twenty participants (39.3%) were in CR1 at enrollment; median age was 5.1 years. Most common non-hematological grade III-IV toxicity was gastrointestinal (n=37). Neutrophil and platelet engraftment occurred at a median of 15 and 24 days, respectively. Twenty-six (51%) participants remain alive at a median of 6.4 years after AHCT. CY 3.75 g/m(2), and targeted topotecan followed by AHCT are feasible and produce acceptable toxicity in children with high-risk malignancies.
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Affiliation(s)
- K A Kasow
- Division of Pediatric Hematology/Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7236, USA.
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14
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Tsakalozou E, Horn J, Leggas M. An HPLC assay for the lipophilic camptothecin analog AR-67 carboxylate and lactone in human whole blood. Biomed Chromatogr 2011; 24:1045-51. [PMID: 20853460 DOI: 10.1002/bmc.1404] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
AR-67 (7-t-butyldimethylsilyl-10-hydroxycamptothecin, DB-67) is a camptothecin analog currently in early stage clinical trials. The lactone moiety of camptothecins hydrolyzes readily in blood to yield the pharmacologically inactive carboxylate form. However the lactone form of third-generation lipophilic congeners, such as AR-67, is more stable, possibly due to partitioning into red cell membranes. This prompted us to develop a reverse-phase HPLC method with fluorescence detection (excitation 380 nm/emission 560 nm), which could quantitate the concentration of AR-67 lactone and carboxylate in whole blood. Samples were prepared by red cell lysis, protein precipitation with methanol and centrifugation to remove denatured materials. Recovery was estimated to be >85%. Analytes were eluted isocratically with 0.15 m ammonium acetate buffer containing 10 mm TBAP (pH 6.5) and acetonitrile (65:35, v/v) on a Nova-Pak C(18) column (4 µm; 3.9 × 150 mm). The assay was linear in the ranges 0.5-300 and 2.5-300 ng/mL for carboxylate and lactone, respectively. Accuracy and precision were acceptable. AR-67 forms were stable in whole blood and in methanolic supernatants. This assay has been successfully applied to measure AR-67 concentrations in whole blood of patients enrolled in a phase I study.
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Affiliation(s)
- Eleftheria Tsakalozou
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA
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Carcaboso AM, Elmeliegy MA, Shen J, Juel SJ, Zhang ZM, Calabrese C, Tracey L, Waters CM, Stewart CF. Tyrosine kinase inhibitor gefitinib enhances topotecan penetration of gliomas. Cancer Res 2010; 70:4499-508. [PMID: 20460504 DOI: 10.1158/0008-5472.can-09-4264] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, increases brain parenchymal extracellular fluid (ECF) accumulation of topotecan, a substrate of the ATP-binding cassette (ABC) transporters P-glycoprotein (Pgp/MDR-1) and breast cancer resistance protein (BCRP/ABCG2). The effect of modulating these transporters on topotecan penetration in gliomas has not been thoroughly studied. Thus, we performed intracerebral microdialysis on mice bearing orthotopic human gliomas (U87 and MT330) and assessed topotecan tumor ECF (tECF) penetration and the effect of gefitinib on topotecan tECF penetration and intratumor topotecan distribution. We found that topotecan penetration (P(tumor)) of U87 was 0.96 +/- 0.25 (n = 7) compared with that of contralateral brain (P(contralateral), 0.42 +/- 0.11, n = 5; P = 0.001). In MT330 tumors, P(tumor) (0.78 +/- 0.26, n = 6) and P(contralateral) (0.42 +/- 0.11, n = 5) also differed significantly (P = 0.013). Because both tumor models had disrupted blood-brain barriers and similar P(tumor) values, we used U87 and a steady-state drug administration approach to characterize the effect of gefitinib on topotecan P(tumor). At equivalent plasma topotecan exposures, we found that P(tumor) after gefitinib administration was lower. In a separate cohort of animals, we determined the volume of distribution of unbound topotecan in tumor (V(u,tumor)) and found that it was significantly higher in groups receiving gefitinib, implying that gefitinib administration leads to a greater proportion of intracellular topotecan. Our results provide crucial insights into the role that transporters play in central nervous system drug penetration and provide a better understanding of the effect of coadministration of transporter modulators on anticancer drug distribution within a tumor.
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Affiliation(s)
- Angel M Carcaboso
- Departments of Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105-2794, USA
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