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Xie J, Span M, van Maarseveen E, Langenhorst J, Boddy AV, Sia KCS, Sutton R, Venn N, Punt AM, Tyrrell V, Haber M, Trahair T, Lau L, Marshall GM, Lock RB. Optimization of a clofarabine-based drug combination regimen for the preclinical evaluation of pediatric acute lymphoblastic leukemia. Pediatr Blood Cancer 2020; 67:e28133. [PMID: 31876116 DOI: 10.1002/pbc.28133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 11/12/2019] [Accepted: 12/01/2019] [Indexed: 12/25/2022]
Abstract
BACKGROUND The aim of this study was to improve the predictive power of patient-derived xenografts (PDXs, also known as mouse avatars) to more accurately reflect outcomes of clofarabine-based treatment in pediatric acute lymphoblastic leukemia (ALL) patients. PROCEDURE Pharmacokinetic (PK) studies were conducted using clofarabine at 3.5 to 15 mg/kg in mice. PDXs were established from relapsed/refractory ALL patients who exhibited good or poor responses to clofarabine. PDX engraftment and response to clofarabine (either as a single agent or in combinations) were assessed based on stringent objective response measures modeled after the clinical setting. RESULTS In naïve immune-deficient NSG mice, we determined that a clofarabine dose of 3.5 mg/kg resulted in systemic exposures equivalent to those achieved in pediatric ALL patients treated with clofarabine-based regimens. This dose was markedly lower than the doses of clofarabine used in previously reported preclinical studies (typically 30-60 mg/kg) and, when scheduled consistent with the clinical regimen (daily × 5), resulted in 34-fold lower clofarabine exposures. Using a well-tolerated clofarabine/etoposide/cyclophosphamide combination regimen, we then found that the responses of PDXs better reflected the clinical responses of the patients from whom the PDXs were derived. CONCLUSIONS This study has identified an in vivo clofarabine treatment regimen that reflects the clinical responses of relapsed/refractory pediatric ALL patients. This regimen could be used prospectively to identify patients who might benefit from clofarabine-based treatment. Our findings are an important step toward individualizing prospective patient selection for the use of clofarabine in relapsed/refractory pediatric ALL patients and highlight the need for detailed PK evaluation in murine PDX models.
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Affiliation(s)
- Jinhan Xie
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
| | - Miriam Span
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
| | - Erik van Maarseveen
- Clinical Pharmacy, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Jurgen Langenhorst
- Clinical Pharmacy, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Alan V Boddy
- UniSA Cancer Research Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
| | - Keith C S Sia
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
| | - Rosemary Sutton
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
| | - Nicola Venn
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
| | - Arjen M Punt
- Clinical Pharmacy, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Vanessa Tyrrell
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
| | - Michelle Haber
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
| | - Toby Trahair
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia.,Kids Cancer Centre, Sydney Children's Hospital, Randwick, Australia
| | - Loretta Lau
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia.,Kids Cancer Centre, Sydney Children's Hospital, Randwick, Australia
| | - Glenn M Marshall
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia.,Kids Cancer Centre, Sydney Children's Hospital, Randwick, Australia
| | - Richard B Lock
- Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia
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Krakow EF, Gyurkocza B, Storer BE, Chauncey TR, McCune JS, Radich JP, Bouvier ME, Estey EH, Storb R, Maloney DG, Sandmaier BM. Phase I/II multisite trial of optimally dosed clofarabine and low-dose TBI for hematopoietic cell transplantation in acute myeloid leukemia. Am J Hematol 2020; 95:48-56. [PMID: 31637757 DOI: 10.1002/ajh.25665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 10/15/2019] [Accepted: 10/16/2019] [Indexed: 11/11/2022]
Abstract
Clofarabine is an immunosuppressive purine nucleoside analog that may have better anti-leukemic activity than fludarabine. We performed a prospective phase I/II multisite trial of clofarabine with 2 Gy total body irradiation as non-myeloablative conditioning for allogeneic hematopoietic cell transplantation in adults with acute myeloid leukemia who were unfit for more intense regimens. Our main objective was to improve the 6-month relapse rate following non-myeloablative conditioning, while maintaining historic rates of non-relapse mortality (NRM) and engraftment. Forty-four patients, 53 to 74 (median: 69) years, were treated with clofarabine at 150 to 250 mg/m2 , of whom 36 were treated at the maximum protocol-specified dose. One patient developed multifactorial acute kidney injury and another developed multiorgan failure, but no other grade 3 to 5 non-hematologic toxicities were observed. All patients fully engrafted. The 6-month relapse rate was 16% (95% CI, 5%-27%) among all patients and 14% (95% CI, 3%-26%) among high-risk patients treated at the maximum dose, meeting the pre-specified primary efficacy endpoint. Overall survival was 55% (95% CI, 40%-70%) and leukemia-free survival was 52% (95% CI, 37%-67%) at 2 years. Compared to a historical high-risk cohort treated with the combination of fludarabine at 90 mg/m2 and 2 Gy TBI, protocol patients treated with the clofarabine-TBI regimen had lower rates of overall mortality (HR of 0.50, 95% CI, 0.28-0.91), disease progression or death (HR 0.48, 95% CI, 0.27-0.85), and morphologic relapse (HR 0.30, 95% CI, 0.13-0.69), and comparable NRM (HR 0.85, 95% CI 0.36-2.00). The combination of clofarabine with TBI warrants further investigation in patients with high-risk AML.
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Affiliation(s)
- Elizabeth F. Krakow
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
- Department of MedicineUniversity of Washington Seattle Washington
| | - Boglarka Gyurkocza
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
| | - Barry E. Storer
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
| | - Thomas R. Chauncey
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
- Department of MedicineUniversity of Washington Seattle Washington
- Bone Marrow Transplant Unit, VA Puget Sound Health Care System Seattle Washington
| | - Jeannine S. McCune
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
- Department of PharmaceuticsUniversity of Washington Seattle Washington
| | - Jerald P. Radich
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
- Department of MedicineUniversity of Washington Seattle Washington
| | - Michelle E. Bouvier
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
| | - Elihu H. Estey
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
- Department of MedicineUniversity of Washington Seattle Washington
| | - Rainer Storb
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
- Department of MedicineUniversity of Washington Seattle Washington
| | - David G Maloney
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
- Department of MedicineUniversity of Washington Seattle Washington
| | - Brenda M. Sandmaier
- Clinical Research DivisionFred Hutchinson Cancer Research Center Seattle Washington
- Department of MedicineUniversity of Washington Seattle Washington
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Im MM, Flanagan SA, Ackroyd JJ, Knapp B, Kramer A, Shewach DS. Late DNA Damage Mediated by Homologous Recombination Repair Results in Radiosensitization with Gemcitabine. Radiat Res 2016; 186:466-477. [PMID: 27740890 DOI: 10.1667/rr14443.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Gemcitabine (dFdCyd) shows broad antitumor activity in solid tumors in chemotherapeutic regimens or when combined with ionizing radiation (radiosensitization). While it is known that mismatches in DNA are necessary for dFdCyd radiosensitization, the critical event resulting in radiosensitization has not been identified. Here we hypothesized that late DNA damage (≥24 h after drug washout/irradiation) is a causal event in radiosensitization by dFdCyd, and that homologous recombination repair (HRR) is required for this late DNA damage. Using γ-H2AX as a measurement of DNA damage in MCF-7 breast cancer cells, we demonstrate that 10 or 80 nM dFdCyd alone produced significantly more late DNA damage compared to that observed within 4 h after treatment. The combination of dFdCyd treatment followed by irradiation did not produce a consistent increase in DNA damage in the first 4 h after treatment, however, there was a synergistic increase 24-48 h later relative to treatment with dFdCyd or radiation alone. RNAi suppression of the essential HRR protein, XRCC3, significantly decreased both radiosensitization and late DNA damage. Furthermore, inhibition of HRR with the Rad51 inhibitor B02 prevented radiosensitization when added after, but not during, treatment with dFdCyd and radiation. To our knowledge, this is the first published study to show that radiosensitization with dFdCyd results from a synergistic increase in DNA damage at 24-48 h after drug and radiation treatment, and that this damage and radiosensitization require HRR. These results suggest that tumors that overexpress HRR will be more vulnerable to chemoradiotherapy, and treatments that increase HRR and/or mismatches in DNA will enhance dFdCyd radiosensitization.
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Affiliation(s)
- Michael M Im
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Sheryl A Flanagan
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Jeffrey J Ackroyd
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Brendan Knapp
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Aaron Kramer
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Donna S Shewach
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109
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C646, a selective small molecule inhibitor of histone acetyltransferase p300, radiosensitizes lung cancer cells by enhancing mitotic catastrophe. Radiother Oncol 2014; 111:222-7. [PMID: 24746574 DOI: 10.1016/j.radonc.2014.03.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 03/03/2014] [Accepted: 03/18/2014] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND PURPOSE Chromatin remodeling through histone modifications, including acetylation, plays an important role in the appropriate response to DNA damage induced by ionizing radiation (IR). Here we investigated the radiosensitizing effect of C646, a selective small molecule inhibitor of p300 histone acetyltransferase, and explored the underlying mechanisms. MATERIALS AND METHODS A549, H157 and H460 human non-small cell lung carcinoma (NSCLC) cells, and HFL-III human lung fibroblasts were assessed by clonogenic survival assay. Apoptosis and necrosis were assessed by annexin V staining. Senescence was assessed by Senescence-associated β-galactosidase staining. Mitotic catastrophe was assessed by evaluating nuclear morphology with DAPI staining. Cell cycle profiles were analyzed by flow cytometry. Protein expression was analyzed by immunoblotting. RESULTS C646 sensitized A549, H460 and H157 cells to IR with a dose enhancement ratio at 10% surviving fraction of 1.4, 1.2 and 1.2, respectively. C646 did not radiosensitize HFL-III cells. In A549 cells, but not in HFL-III cells, C646 (i) enhanced mitotic catastrophe but not apoptosis, necrosis, or senescence after IR; (ii) increased the hyperploid cell population after IR; and (iii) suppressed the phosphorylation of CHK1 after IR. CONCLUSIONS C646 radiosensitizes NSCLC cells by enhancing mitotic catastrophe through the abrogation of G2 checkpoint maintenance.
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Synthesis, in vitro aerobic and hypoxic cytotoxicity and radiosensitizing activity of novel metronidazole tethered 5-fluorouracil. ACTA ACUST UNITED AC 2013; 21:76. [PMID: 24359860 PMCID: PMC3914007 DOI: 10.1186/2008-2231-21-76] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Accepted: 09/13/2013] [Indexed: 11/10/2022]
Abstract
Background and the purpose of the study Several 2, 4-dinitrophenyl and 2,4-dinitrophenylamine tethered 5-FU (5-fluorouracil) compared to their components have shown minimal or no cytotoxicity to HT-29 cell line under aerobic conditions but high cytotoxicity and radiosensitizing effects under hypoxic conditions. In the present study the cytotoxicity and radiation potentiation of three novel analogues of these compounds by replacing 2,4-dinitrophenyl moiety with 2-methyl-5-nitroimidazole, a known radiosensitizer and cytotoxic agent was investigated. Methods Tethered compounds 7–9 were prepared by the reaction of 1-(t-butoxycarbonyl)-5-fluorouracil 6 with metronidazole esters 2–4 followed by removal of the t-butoxycarbonyl protecting group. Cytotoxicity of compounds in HT-29 cells with or without radiation were determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), propidium iodide (PI)-digitonin and clonogenic assays. Results Tethered compounds 7–9 induced time-and concentration–dependent cytotoxicity under hypoxia but had no significant effect under aerobic conditions. These compounds also showed selective and concentration- dependent radiosensitization effects under hypoxic conditions. Conclusion Tethered compounds 7–9 compared to 5-FU 5 showed minimal cytotoxicities under aerobic and selective radiosensitizing activities under hypoxic conditions. Also effects of these compounds were higher than those of metronidazole 1 which is a known cytotoxin and radiosensitizer under hypoxic conditions.
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Khalaj A, Abdi K, Ostad SN, Khoshayand MR, Lamei N, Nedaie HA. Synthesis,In VitroCytotoxicity and Radiosensitizing Activity of Novel 3-[(2,4-Dinitrophenylamino)Alkyl] Derivatives of 5-Fluorouracil. Chem Biol Drug Des 2013; 83:183-90. [DOI: 10.1111/cbdd.12211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 08/10/2013] [Accepted: 08/12/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Ali Khalaj
- Department of Medicinal Chemistry; Faculty of Pharmacy; Tehran University of Medical Sciences; Tehran Iran
- Drug Design & Development Research Center; Tehran University of Medical Sciences; Tehran Iran
| | - Khosrou Abdi
- Department of Medicinal Chemistry; Faculty of Pharmacy; Tehran University of Medical Sciences; Tehran Iran
- Department of Radiopharmacy; Faculty of Pharmacy; Tehran University of Medical Sciences; Tehran Iran
| | - Seyed Nasser Ostad
- Department of Toxicology and Pharmacology; Faculty of Pharmacy; Tehran University of Medical Sciences; Tehran Iran
| | - Mohammad Reza Khoshayand
- Department of Drug and Food Control; Faculty of Pharmacy; Tehran University of Medical Sciences; Tehran Iran
| | - Navid Lamei
- Drug Design & Development Research Center; Tehran University of Medical Sciences; Tehran Iran
| | - Hasan Ali Nedaie
- Department of Radiotherapy; Oncology Cancer Institute; Tehran University of Medical Sciences; Tehran Iran
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Lee MW, Parker WB, Xu B. New insights into the synergism of nucleoside analogs with radiotherapy. Radiat Oncol 2013; 8:223. [PMID: 24066967 PMCID: PMC3851323 DOI: 10.1186/1748-717x-8-223] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 09/24/2013] [Indexed: 11/18/2022] Open
Abstract
Nucleoside analogs have been frequently used in combination with radiotherapy in the clinical setting, as it has long been understood that inhibition of DNA repair pathways is an important means by which many nucleoside analogs synergize. Recent advances in our understanding of the structure and function of deoxycytidine kinase (dCK), a critical enzyme required for the anti-tumor activity for many nucleoside analogs, have clarified the mechanistic role this kinase plays in chemo- and radio-sensitization. A heretofore unrecognized role of dCK in the DNA damage response and cell cycle machinery has helped explain the synergistic effect of these agents with radiotherapy. Since most currently employed nucleoside analogs are primarily activated by dCK, these findings lend fresh impetus to efforts focused on profiling and modulating dCK expression and activity in tumors. In this review we will briefly review the pharmacology and biochemistry of the major nucleoside analogs in clinical use that are activated by dCK. This will be followed by discussions of recent advances in our understanding of dCK activation via post-translational modifications in response to radiation and current strategies aimed at enhancing this activity in cancer cells.
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Affiliation(s)
- Michael W Lee
- Department of Medical Education, College of Medicine, University of Central Florida, 6850 Lake Nona Blvd,, Orlando, FL 32827, USA.
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Zhuang HQ, Bo QF, Yuan ZY, Wang J, Zhao LJ, Wang P. The different radiosensitivity when combining erlotinib with radiation at different administration schedules might be related to activity variations in c-MET-PI3K-AKT signal transduction. Onco Targets Ther 2013; 6:603-8. [PMID: 23745052 PMCID: PMC3671795 DOI: 10.2147/ott.s44505] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
OBJECTIVES The aim of this paper was to investigate the efficacy and activity variation associated with phosphoinositide 3-kinase (PI3K) signal transduction when combining erlotinib with radiation, using different administration schedules. MATERIALS AND METHODS Erlotinib was delivered to A973 cancer cells in the following three ways: (1) irradiation after administration, (2) irradiation upon administration, and, (3) irradiation before administration. The cell-survival rates were detected using colony-forming assays, while cell apoptosis was detected with flow cytometry. The expression levels of C-MET, p-C-MET, AKT, and p-AKT were determined via Western blotting analysis, under 6 Gy irradiation with/ without erlotinib. RESULTS The sensitizer enhancement ratios (SERs) of erlotinib irradiation after administration, irradiation upon administration, and irradiation before administration groups were 2.19, 1.53, and 1.38, respectively. A higher apoptosis rate was observed when irradiation was delivered after erlotinib. In addition, changes in cell apoptosis were found to be related to concurrent changes in C-MET, p-C-MET, AKT, and p-AKT expression. Protein expression increased in the combination groups, with trends showing a negative relationship with cell apoptosis. CONCLUSION The radiosensitive effect of erlotinib varied because of the different administration schedules; this variation may be related to PI3K signal transduction and its associated regulating effect.
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Affiliation(s)
- Hong-Qing Zhuang
- Department of Radiotherapy, Tianjin Cancer Institute and Hospital, Tianjin Key Laboratory of Cancer Prevention and Therapy, and Tianjin Lung Cancer Center, Tianjin, People's Republic of China
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Stackhouse MA, Gilbert KS, Scoggins JW, Waud WR. Preclinical combination therapy of clofarabine plus radiation. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2013; 31:692-705. [PMID: 23004932 DOI: 10.1080/15257770.2012.723770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Clofarabine, an approved anticancer drug, was evaluated in combination with radiation in six subcutaneously implanted human tumor xenograft models. Clofarabine had no effect on the growth of SF-295 glioblastoma, which was not enhanced by radiation. There was no difference between clofarabine with and without radiation in the DU-145 prostate model. The combined effect on NCI-H460 lung tumors appeared to be additive. SR475 head and neck, PANC-1 pancreatic, and HCT-116 colon tumors were radiomodified by clofarabine. The radiomodifying capacity of clofarabine was superior to that for gemcitabine in two models (PANC-1 and HCT-116) and was comparable in the other four models.
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Affiliation(s)
- Murray A Stackhouse
- Department of Cancer Therapeutics and Immunology, Southern Research Institute, Birmingham, Alabama, USA
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Abdi K, Khalaj A, Ostad SN, Khoshayand MR. Cytotoxicity and radiosensitising activity of synthesized dinitrophenyl derivatives of 5-fluorouracil. ACTA ACUST UNITED AC 2012; 20:3. [PMID: 23226112 PMCID: PMC3514535 DOI: 10.1186/1560-8115-20-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 07/19/2012] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND THE PURPOSE OF THE STUDY Dual functional agents in which nitroaromatic or nitroheterocyclic compounds are attached through a linker unit to mustards and aziridines have shown higher cytotoxicities than the corresponding counterparts to both aerobic and hypoxic cells and enhanced radiosensitizing activity. In the present investigation cytotoxicity and radiosensitizing activity of 2,4-dinitrobenzyl, 2,4-dinitrobenzoyl, and 2,4-dinitrophenacetyl derivatives of 5-fluorouracil which was assumed to release cytotoxic active quinone methidide and 5-fluorouracil under hypoxic conditions on HT-29 cell line under both aerobic and hypoxic conditions was investigated. METHODS 5-fluorouracil derivative X-XIII were prepared by the reaction of the corresponding di-nitro substituted benzyl, benzoyl and phenacetyl halides with 5-fluorouracil protected at N-1 with di-t-butoxydicarbonate (BOC) in dimethyl formamide (DMF) in the presence of the potassium carbonate followed by hydrolysis of the blocking group by potassium carbonate in methanol. Cytotoxicity of fluorouracil VIII and tested compounds X-XIII against HT-29 cell line under both aerobic and hypoxic conditions after 48 hrs incubation were measured by determination of the percent of the survival cells using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and percent of the dead cells using propidium iodide(PI)-digitonine assay and results were used to calculate the corresponding IC(50) values. Radiosensitization experiments were carried out by irradiation of the incubations with a (60)Co source and clonogenic assay was performed to determine the cell viabilities following treatment with the tested compounds and/or radiation. Sensitization Enhancement Ratio (SER) of each tested compound was obtained from the radiation survival curves in the absence and presence of each sensitizer for 37% survival respectively. RESULTS AND MAJOR CONCLUSION Findings of the present study showed that alkylation or acylation of 5-fluorouracil result in compounds which have little or no cytotoxicity and radiosensitizing activity under aerobic conditions, but have high cytotoxicity and radiosensitizing effects under hypoxic conditions. Furthermore radiosensitizing activities of compounds under hypoxic conditions increased by increase in their concentrations and SER of the tested 5-FU derivatives at concentrations higher than 50 μmol were equal or higher than 1.6 which is the minimum effective SER of a radiosensitizer in an in vitro assay.
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Affiliation(s)
- Khosrou Abdi
- Department of Medicinal Chemistry, Tehran, Iran ; Department of Nuclear Pharmacy, Tehran, Iran
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Abe C, Uto Y, Nakae T, Shinmoto Y, Sano K, Nakata H, Teraoka M, Endo Y, Maezawa H, Masunaga SI, Nakata E, Hori H. Evaluation of the in vivo radiosensitizing activity of etanidazole using tumor-bearing chick embryo. JOURNAL OF RADIATION RESEARCH 2011; 52:208-214. [PMID: 21436611 DOI: 10.1269/jrr.10122] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Chick embryos have been used as alternative experimental animals in various research fields, including virology, immunology, toxicology, oncology, and embryology. Until now, there have been no in vivo models using chick embryo to evaluate radiosensitizing activity. Here, the in vivo radiosensitizing activity of etanidazole, a well-known hypoxic cell radiosensitizer, was evaluated using tumor-bearing chick embryo. On the basis of tumor growth, drug administration and X-ray irradiation were performed on day 15 chick embryo, with the endpoint being day 18 chick embryo. In day 15 chick embryo, an X-ray irradiation dose of equal or less than 10 Gy did not cause significant tumor growth suppression. Intravenous administration of equal or less than 1.0 mg of etanidazole did not cause tumor growth suppression. Neither doses of equal or less than 8 Gy of irradiation nor 1.0 mg of etanidazole caused fatality of the chick embryo. On the basis of these results, we evaluated the radiosensitizing effect of a combination treatment with 8 Gy of irradiation and 1.0 mg of etanidazole. As noted above, 1.0 mg of etanidazole alone and 8 Gy of irradiation alone did not show tumor growth suppression. In contrast, a combination treatment with 8 Gy of irradiation and 1.0 mg of etanidazole showed 35% of significant tumor growth suppression. Thus, we succeeded in evaluating the in vivo radiosensitizing activity of etanidazole using tumor-bearing chick embryo. These results suggest that the use of tumor-bearing chick embryo may be part of a promising system for evaluating radiosensitizing activity.
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Affiliation(s)
- Chiaki Abe
- Department of Life System, Institute of Technology and Science, Graduate School, The University of Tokushima, Tokushima, Japan
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Seedhouse C, Grundy M, Shang S, Ronan J, Pimblett H, Russell N, Pallis M. Impaired S-phase arrest in acute myeloid leukemia cells with a FLT3 internal tandem duplication treated with clofarabine. Clin Cancer Res 2009; 15:7291-8. [PMID: 19934300 DOI: 10.1158/1078-0432.ccr-09-1222] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Acute myeloid leukemia cells with an internal tandem duplication mutation of FLT3 (FLT3-ITD) have effective DNA repair mechanisms on exposure to drugs. Despite this, the phenotype is not associated with primary resistant disease. We show defects in the response of mutant FLT3 AML cells to the S-phase drug clofarabine that could account for the apparent contradiction. EXPERIMENTAL DESIGN We studied responses of AML cells to clofarabine in vitro. RESULTS When treated with a short pulse of clofarabine, FLT3-ITD-harboring MOLM-13 and MV4.11 cells undergo similar damage levels (gammaH2AX foci) to wild-type cells but have a better repair capability than wild-type cells. However, whereas the wild-type cells undergo rapid S-phase arrest, the S-phase checkpoint fails in mutant cells. Cell cycle arrest in response to DNA damage in S phase is effected via loss of the transcriptional regulator cdc25A. This loss is reduced or absent in clofarabine-treated FLT3 mutant cells. Furthermore, cdc25A message levels are maintained by the FLT3-ITD, such that message is reduced by 87.5% on exposure to FLT3 small interfering RNA. Primary FLT3-ITD samples from untreated patients also display impaired cell cycle arrest and show enhanced sensitivity on prolonged treatment with clofarabine compared with wild-type samples. CONCLUSION There is a reversal of phenotype in mutant FLT3 cells dependent on the length of exposure to clofarabine. Efficient DNA repair may render the cells resistant to a short pulse of the drug, but a failure of cell cycle checkpoint(s) in S phase renders the cells sensitive to prolonged exposure.
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Zhenchuk A, Lotfi K, Juliusson G, Albertioni F. Mechanisms of anti-cancer action and pharmacology of clofarabine. Biochem Pharmacol 2009; 78:1351-9. [PMID: 19576186 DOI: 10.1016/j.bcp.2009.06.094] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 06/21/2009] [Accepted: 06/23/2009] [Indexed: 11/19/2022]
Abstract
Clofarabine, a next-generation deoxyadenosine analogue, was developed on the basis of experience with cladribine and fludarabine in order to achieve higher efficacy and avoid extramedullary toxicity. During the past decade this is the only drug granted approval for treatment of pediatric acute leukemia. Recent clinical studies have established the efficacy of clofarabine in treating malignancies with a poor prognosis, such as adult, elderly, and relapsed pediatric leukemia. The mechanisms of its anti-cancer activity involve a combination of direct inhibition of DNA synthesis and ribonucleotide reductase and induction of apoptosis. Due to this broad cytotoxicity, this drug is effective against various subtypes of leukemia and is currently being tested as an oral formulation and for combination therapy of both leukemias and solid tumors. In this review we summarize current knowledge pertaining to the molecular mechanisms of action and pharmacological properties of clofarabine, as well as clinical experiences with this drug with the purpose of facilitating the evaluation of its efficacy and the development of future therapies.
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Affiliation(s)
- Anna Zhenchuk
- Department of Oncology-Pathology, Cancer Center Karolinska, Karolinska Institute, Karolinska Hospital, SE-17176 Stockholm, Sweden
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Bischoff P, Altmeyer A, Dumont F. Radiosensitising agents for the radiotherapy of cancer: advances in traditional and hypoxia targeted radiosensitisers. Expert Opin Ther Pat 2009; 19:643-62. [DOI: 10.1517/13543770902824172] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Affiliation(s)
- Peng Liu
- The University of Georgia, College of Pharmacy, Athens, GA 30602
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