Sample records for floxuridine
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DNA Trojan Horses: Self-Assembled Floxuridine-Containing DNA Polyhedra for Cancer Therapy.
Mou, Quanbing; Ma, Yuan; Pan, Gaifang; Xue, Bai; Yan, Deyue; Zhang, Chuan; Zhu, Xinyuan
2017-10-02
Based on their structural similarity to natural nucleobases, nucleoside analogue therapeutics were integrated into DNA strands through conventional solid-phase synthesis. By elaborately designing their sequences, floxuridine-integrated DNA strands were synthesized and self-assembled into well-defined DNA polyhedra with definite drug-loading ratios as well as tunable size and morphology. As a novel drug delivery system, these drug-containing DNA polyhedra could ideally mimic the Trojan Horse to deliver chemotherapeutics into tumor cells and fight against cancer. Both in vitro and in vivo results demonstrate that the DNA Trojan horse with buckyball architecture exhibits superior anticancer capability over the free drug and other formulations. With precise control over the drug-loading ratio and structure of the nanocarriers, the DNA Trojan horse may play an important role in anticancer treatment and exhibit great potential in translational nanomedicine. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Creaven, P J; Rustum, Y M; Petrelli, N J; Meropol, N J; Raghavan, D; Rodriguez-Bigas, M; Levine, E G; Frank, C; Udvary-Nagy, S; Proefrock, A
1994-01-01
A phase I and pharmacokinetics study was carried out of floxuridine (FdUrd) modulated by leucovorin (LV) given on the Roswell Park regimen (LV given at 500 mg/m2 by 2-h infusion and FdUrd given by i.v. push at 1 h after the start of LV infusion, treatment being given weekly x 6). The dose-limiting toxicity was diarrhea; the MTD and recommended dose for phase II studies was 1,650 mg/m2 per week of FdUrd. The dose-response curve was steep, with 3/3 patients treated at a dose of 1,750 mg/m2 developing grade IV diarrhea. With this schedule there was no significant mucositis. Pharmacokinetic parameters showed very wide interpatient variability. Plasma decay was biphasic with a t1/2 beta of approximately 2 h. Plasma clearance was high (> 200 1 h-1). No correlation between pharmacokinetic parameters and toxicity could be identified.
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Gao, Ling-Jie; De Jonghe, Steven; Daelemans, Dirk; Herdewijn, Piet
2016-05-01
A series of novel aryloxyphosphoramidate nucleoside prodrugs based on l-aspartic acid and l-glutamic acid as amino acid motif has been synthesized and evaluated for antitumoral activity. Depending on the cancer cell line studied and on the nature of the parent nucleoside compound (gemcitabine, 5-iodo-2'-deoxy-uridine, floxuridine or brivudin), the corresponding ProTides are endowed with an improved or decreased cytotoxic activity. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Kemeny, Nancy; Eid, Ahmed; Stockman, Jennifer; Gonen, Mithat; Schwartz, Lawrence; Tetzlaff, Eric; Paty, Philip
2005-08-01
In vitro data suggest increased cytotoxicity with Mitomycin C (Mit-C) and Floxuridine (FUDR). Based on these data, we performed a phase II trial of hepatic arterial infusion (HAI) of FUDR and Dexamethasone (Dex) plus high-dose Mit-C for patients with unresectable hepatic metastases from colorectal carcinoma. High-dose Mit-C (15 mg/m2) was added via the pump sideport to HAI FUDR and Dex for 14 days of a 28-day cycle. Mit-C was given on days 1 and 29, and FUDR was given indefinitely until disease progression or discontinuation of therapy due to toxicity. Sixty-three patients with unresectable liver metastases were entered. The chemotherapy-naïve group (n = 26) and those previously treated (n = 37) had similar response and median survival: 73% and 70%, and 23 and 20 months, respectively. The major toxicities were liver bilomas (7.9%), elevation in bilirubin level >3 (22%), and biliary sclerosis (9.5%). Hematologic and gastrointestinal toxicity was less than 2%. The addition of high-dose Mit-C to HAI FUDR and Dex produced a high response rate even in previously treated patients. The median survival was 21 months even though half the patients were previously treated with chemotherapy. Biliary toxicity was higher than expected; therefore, alternatives to high dose Mit-C should be investigated when exploring additions to HAI therapy with FUDR and Dex. Copyright 2005 Wiley-Liss, Inc.
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Chemotherapy induced toxicity is highly heritable in Drosophila melanogaster
Kislukhin, Galina; Murphy, Maura L.; Jafari, Mahtab; Long, Anthony D.
2012-01-01
Objectives Identifying the genes responsible for chemotherapy toxicity in Drosophila melanogaster may allow for the identification of human orthologs that similarly mediate toxicity in humans. In order to develop Drosophila melanogaster as a model of dissecting chemotoxicity, we first need to develop standardized high throughput toxicity assays and prove that inter-individual variation in toxicity as measured by such assays is highly heritable. Methods We developed a method for the oral delivery of commonly used chemotherapy drugs to Drosophila. Post-treatment female fecundity displayed a dose dependent response to varying levels of the chemotherapy drug delivered. We fixed the dose for each drug at a level that resulted in a 50% reduction in fecundity and used a paternal half-sibling heritability design to calculate the heritability attributable to chemotherapy toxicity assayed via a decrease in female fecundity. Chemotherapy agents tested were carboplatin, floxuridine, gemcitabine hydrochloride, methotrexate, mitomycin C, and topotecan hydrochloride. Results We found that six currently widely prescribed chemotherapeutic agents lowered fecundity in D. melanogaster in both a dose dependent and highly heritable manner. The following heritability estimates were found: carboplatin – 0.72, floxuridine – 0.52, gemcitabine hydrochloride – 0.72, methotrexate – 0.99, mitomycin C – 0.64, and topotecan hydrochloride – 0.63. Conclusions The high heritability estimates observed in this study, irrespective of the particular class of drug examined, suggest that human toxicity may also have a sizable genetic component. PMID:22336958
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Han, Youngkyu; Zhang, Zhe; Smith, Gregory S.; ...
2017-04-19
In this work, the effect of three nucleoside analogue antimetabolites (5-fluorouracil, floxuridine, and gemcitabine) on the structure of Pluronic L62 copolymer micelles was investigated using small-angle neutron scattering. These antimetabolites used for cancer chemotherapy have analogous molecular structures but different molecular sizes and aqueous solubilities. It was found that the addition of the three antimetabolites slightly reduced the micellar size and aggregation number, and the micellar anisotropy. The added antimetabolites also changed the internal molecular distribution of the micelles as measured by the scattering length densities, resulting in enhanced hydration of the hydrophobic core region of the micelle. The strengthmore » of the effect was found to correlate with the molecular properties of the model drugs, i.e. a larger molecular size and a higher aqueous solubility lead to enhanced hydration of the micellar core.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Han, Youngkyu; Zhang, Zhe; Smith, Gregory S.
2017-01-01
The effect of three nucleoside analogue antimetabolites (5-fluorouracil, floxuridine, and gemcitabine) on the structure of Pluronic L62 copolymer micelles was investigated using small-angle neutron scattering. These antimetabolites used for cancer chemotherapy have analogous molecular structures but different molecular sizes and aqueous solubilities. It was found that the addition of the three antimetabolites slightly reduced the micellar size and aggregation number, and the micellar anisotropy. The added antimetabolites also changed the internal molecular distribution of the micelles as measured by the scattering length densities, resulting in enhanced hydration of the hydrophobic core region of the micelle. The strength of the effectmore » was found to correlate with the molecular properties of the model drugs, i.e. a larger molecular size and a higher aqueous solubility lead to enhanced hydration of the micellar core.« less
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Novel anticancer polymeric conjugates of activated nucleoside analogs
Senanayake, Thulani H.; Warren, Galya; Vinogradov, Serguei V.
2011-01-01
Inherent or therapy-induced drug resistance is a major clinical setback in cancer treatment. The extensive usage of cytotoxic nucleobases and nucleoside analogs in chemotherapy also results in the development of specific mechanisms of drug resistance; such as nucleoside transport or activation deficiencies. These drugs are prodrugs; and being converted into the active mono-, di- and triphosphates inside cancer cells following administration, they affect nucleic acid synthesis, nucleotide metabolism, or sensitivity to apoptosis. Previously, we have actively promoted the idea that the nanodelivery of active nucleotide species, e.g. 5′-triphosphates of nucleoside analogs, can enhance drug efficacy and reduce nonspecific toxicity. In this study we report the development of a novel type of drug nanoformulations, polymeric conjugates of nucleoside analogs, which are capable of the efficient transport and sustained release of phosphorylated drugs. These drug conjugates have been synthesized, starting from cholesterol-modified mucoadhesive polyvinyl alcohol or biodegradable dextrin, by covalent attachment of nucleoside analogs through a tetraphosphate linker. Association of cholesterol moieties in aqueous media resulted in intramolecular polymer folding and the formation of small nanogel particles containing 0.5 mmol/g of a 5′-phosphorylated nucleoside analog, e.g. 5-fluoro-2′-deoxyuridine (floxuridine, FdU), an active metabolite of anticancer drug 5-fluorouracyl (5-FU). The polymeric conjugates demonstrated rapid enzymatic release of floxuridine 5′-phosphate and much slower drug release under hydrolytic conditions (pH 1.0–7.4). Among the panel of cancer cell lines, all studied polymeric FdU-conjugates demonstrated an up to 50 times increased cytotoxicity in human prostate cancer PC-3, breast cancer MCF-7 and MDA-MB-231 cells, and more than 100 times higher efficacy against cytarabine-resistant human T-lymphoma (CEM/araC/8) and gemcitabine-resistant follicular lymphoma (RL7/G) cells as compared to free drugs. In the initial in vivo screening, both PC-3 and RL7/G subcutaneous tumor xenograft models showed enhanced sensitivity to sustained drug release from polymeric FdU-conjugate after peritumoral injections and significant tumor growth inhibition. All these data demonstrate a remarkable clinical potential of novel polymeric conjugates of phosphorylated nucleoside analogs, especially as new therapeutic agents against drug-resistant tumors. PMID:21863885
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Ettinger, L J; Goodell, L A; Javidian, P; Hsieh, Y; Amenta, P
2000-01-01
Renal cell carcinoma is rarely seen in children and adolescents. Patients with widespread disease at diagnosis have a particularly poor survival rate. Currently, all known chemotherapy has been ineffective in improving the median survival in patients with advanced disease. A 13-year-old black boy with stage IV renal cell carcinoma with rhabdoid features is a long-term disease-free survivor after aggressive multiagent chemotherapy. After the initial evaluation and histologic diagnosis of renal cell carcinoma, the patient received three courses of an aggressive chemotherapy regimen consisting of vincristine, doxorubicin, cyclophosphamide with mesna uroprotection, granulocyte colony-stimulating factor and erythropoietin (Epogen). After an almost complete response, a radical nephrectomy was performed and results demonstrated a solitary small nodule with viable tumor. After surgery, he received floxuridine infusion for 14 days by circadian schedule at 28-day intervals for a total of 1 year. The patient is well and free of disease 5 years after initial presentation. The dramatic response to treatment and long-term disease-free survival of this patient suggest this chemotherapeutic approach warrants additional investigation.
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Donson, Andrew M; Amani, Vladimir; Warner, Elliot A; Griesinger, Andrea M; Witt, Davis A; Mulcahy Levy, Jean M; Hoffman, Lindsey M; Hankinson, Todd C; Handler, Michael H; Vibhakar, Rajeev; Dorris, Kathleen; Foreman, Nicholas K
2018-06-20
Children with ependymoma are cured in less than 50% of cases, with little improvement in outcome over the last several decades. Chemotherapy has not impacted survival in ependymoma, due in part to a lack of preclinical models that has precluded comprehensive drug testing. We recently developed two human ependymoma cell lines harboring high-risk phenotypes which provided us with an opportunity to execute translational studies. ependymoma and other pediatric brain tumor cell lines were subject to a large-scale comparative drug screen of ependymoma -approved oncology drugs for rapid clinical application. The results of this in vitro study were combined with in silico prediction of drug sensitivity to identify ependymoma -selective compounds, which were validated by dose curve and time course modelling. Mechanisms of ependymoma -selective antitumor effect were further investigated using transcriptome and proteome analyses. We identified three classes of oncology drugs that showed ependymoma -selective anti-tumor effect, namely (i) fluorinated pyrimidines (5-fluorouracil, carmofur and floxuridine), (ii) retinoids (bexarotene, tretinoin and isotretinoin), and (iii) a subset of small-molecule multi-receptor tyrosine kinase inhibitors (axitinib, imatinib and pazopanib). Axitinib's anti-tumor mechanism in ependymoma cell lines involved inhibition of PDGFR-alpha and PDGFR-beta and was associated with reduced mitosis-related gene expression and cellular senescence. The clinically available, ependymoma -selective oncology drugs identified by our study have the potential to critically inform design of upcoming clinical studies in ependymoma, in particular for those children with recurrent ependymoma who are in the greatest need of novel therapeutic approaches. Copyright ©2018, American Association for Cancer Research.
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Earlam, S; Glover, C; Davies, M; Fordy, C; Allen-Mersh, T G
1997-05-01
Since systemic and regional (HAI) fluorinated pyrimidine chemotherapies offer similar survival benefit in treatment of colorectal liver metastases (CLM), we sought to identify their impact on quality of life (QoL), which might be a useful indicator of treatment preference. We compared QoL in 135 CLM patients managed by symptom control (n = 49 patients), systemic fluorouracil (5FU)/folinic acid (n = 35), or hepatic arterial floxuridine (FUDR) (n = 51). Full blood count and liver function tests, World Health Organization (WHO) toxicity criteria, and QoL (Rotterdam Symptom Checklist [RSC], the Sickness Impact Profile [SIP], and the Hospital Anxiety and Depression scale [HAD]) were measured monthly in all patients. The HAD anxiety score was significantly increased in symptom control compared with chemotherapy patients 1 month after randomization. There was a significant increase in RSC physical score (repeated measures, P = .05), and in scores for sore mouth (P < .01), dry mouth (P < .01), and tingling hands and feet (P < .01) in systemic chemotherapy compared with symptom control patients. Significant QoL differences (repeated measures and Mann-Whitney U [MWU]) between HAI and symptom control patients were not detected. Systemic chemotherapy patients lived for significantly longer (log-rank test, P < or = .0001) with abnormal HAD anxiety, RSC psychosocial, or RSC sore mouth scores compared with HAI patients, but there were no overall survival differences. Randomization to symptom control only was associated with increased anxiety. QoL with systemic chemotherapy was impaired by side effects. HAI was associated with similar survival to systemic chemotherapy but with better sustained QoL.
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Mocellin, Simone; Pilati, Pierluigi; Lise, Mario; Nitti, Donato
2007-12-10
The treatment of unresectable liver-confined metastatic disease from colorectal cancer (CRC) is a challenging issue. Although locoregional treatments such as hepatic arterial infusion (HAI) claim the advantage of delivering higher doses of anticancer agents directly into the affected organ, the benefit in terms of overall survival (OS) is unclear. We quantitatively summarized the results of randomized controlled trials (RCT) comparing HAI with systemic chemotherapy (SCT). To date, 10 RCTs have been published, for a total of 1,277 patients enrolled. For tumor response rates, relative risks (RR) and their 95% CIs were obtained from raw data; for OS, hazard ratios (HRs) and their 95% CIs were extrapolated from the Kaplan-Meier survival curves. HAI regimens were based on floxuridine (FUDR) in nine of 10 RCTs, whereas in one RCT, fluorouracil (FU) + leucovorin was used. SCT consisted of FUDR, FU, FU + leucovorin, or a miscellany of FU and best supportive care in three, one, four, and two studies, respectively. Pooling the data, tumor response rate was 42.9% and 18.4% for HAI and SCT, respectively (RR = 2.26; 95% CI, 1.80 to 2.84; P < .0001). Mean weighted median OS times were 15.9 and 12.4 months for HAI and SCT, respectively; the meta-risk of death was not statistically different between the two study groups (HR = 0.90; 95% CI, 0.76 to 1.07; P = .24). Currently available evidence does not support the clinical or investigational use of fluoropyrimidine-based HAI alone for the treatment of patients with unresectable CRC liver metastases, at least as a first-line therapy.
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Efficacy of hepatic arterial infusion chemotherapy in advanced hepatocellular carcinoma
Baek, Yang Hyun; Kim, Kyoung Tae; Lee, Sung Wook; Jeong, Jin Sook; Park, Byeong Ho; Nam, Kyung Jin; Cho, Jin Han; Kim, Young Hoon; Roh, Young Hoon; Lee, Hyung Sik; Choi, Young Min; Han, Sang Young
2012-01-01
AIM: To investigate the efficacy of hepatic arterial infusion chemotherapy (HAIC) using floxuridine (FUDR) in patients with advanced hepatocellular carcinoma (HCC) confined to the liver. METHODS: Thirty-four patients who had advanced HCC with unresectability or unsuccessful previous therapy in the absence of extrahepatic metastasis were treated with intra-arterial FUDR chemotherapy at our hospital between March 2005 and May 2008. Among the 34 patients, 9 patients were classified as Child class C, and 18 patients had portal vein tumor thrombus (PVTT). One course of chemotherapy consisted of continuous infusion of FUDR (0.3 mg/kg during day 1-14) and dexamethasone (10 mg on day 1, 4, 7 and 11), and this treatment was repeated every 28 d. RESULTS: Two patients (5.9%) displayed a complete response, and 12 patients (35.3%) had a partial response. The tumor control rate was 61.8%. The median overall survival times were 15.3 mo, 12.4 mo and 4.3 mo for the patients who were classified as Child class A, Child class B and Child class C, respectively (P = 0.0392). The progression-free survival was 12.9 mo, 7.7 mo and 2.6 mo for the patients who were classified as Child class A, Child class B and Child class C, respectively (P = 0.0443). The cumulative survival differed significantly according to the Child-Pugh classification and the presence of PVTT. In addition to hepatic reserve capacity and PVTT, the extent of HCC was an independent factor in determining a poor prognosis. The most common adverse reactions to HAIC were mucositis, diarrhea and peptic ulcer disease, but most of these complications were improved by medical treatment and/or a delay of HAIC. CONCLUSION: The present study demonstrates that intra-arterial FUDR chemotherapy is a safe and effective treatment for advanced HCC that is recalcitrant to other therapeutic modalities, even in patients with advanced cirrhosis. PMID:22807613
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Xiao, Changji; Yang, Junjun; Zhao, Jing; Ren, Tong; Feng, Fengzhi; Wan, Xirun; Xiang, Yang
2015-04-28
The optimal treatment for patients with brain metastasis from gestational trophoblastic neoplasia (GTN) has not been established. This study aims to investigate the clinical characteristics and the management of brain metastasis from GTN in relation to patients' outcomes. We retrospectively investigated 109 GTN patients with brain metastasis treated at Peking Union Medical College Hospital from January 1990 to December 2013. Patients mainly received multiagent chemotherapy with florouracil or floxuridine, dactinomycin, etoposide, and vincristine (FAEV) combined with intrathecal methotrexate with or without surgery. In the 109 patients, sixty-two (56.1%) patients presented for primary therapy and 47 patients had failed chemotherapy elsewhere. Eight early demise patients who died before or during first cycle of chemotherapy were excluded from analysis. The median follow-up time was 47 months (range 9-180 months). The overall 5-year survival rate (OS) was 71.1%, while the OS rate for patients receiving primary chemotherapy in our hospital was 85.5%, and this fell to 51.9% in patients with failure multidrug chemotherapy elsewhere. Multivariate analysis demonstrated that International Federation of Gynecology and Obstetrics (FIGO) scores over 12 (Hazard ratio-HR 1.279, 95% CI 1.061-1.541, P = 0.010), failure of previous multidrug chemotherapy (HR 3.177, 95% CI 1.277-7.908, P = 0.013), and concurrent renal metastasis (HR 2.654, 95% CI 1.125-6.261, P = 0.026) were the risk factors of overall survival in patients with brain metastases from GTN. Patients with brain metastasis from GTN have favorable outcome by multidrug chemotherapy and adjuvant therapies. Nevertheless, the prognosis is poor if the patients had previous multidrug failure chemotherapy history, concomitant with renal metastasis, or FIGO score over 12. Initial treatment with FAEV combined with intrathecal methotrexate chemotherapy can bring bright prospect to patients with brain metastases from GTN.
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Mocellin, Simone; Pasquali, Sandro; Nitti, Donato
2009-07-08
Although locoregional treatments such as hepatic arterial infusion (HAI) claim the advantage of delivering higher doses of anticancer agents directly into the metastatic organ as compared to systemic chemotherapy (SCT), the benefit in terms of overall survival (OS) is unclear. We quantitatively summarized the results of randomised controlled trials (RCT) comparing HAI to SCT for the treatment of unresectable liver metastatic disease from colorectal cancer (CRC). The aim of this work is to quantitatively summarize the results of RCT comparing HAI to SCT for the treatment of unresectable hepatic metastases from CRC. A systematic review of reports published until September 2008 on the findings of RCT that compared HAI to SCT for the treatment of unresectable CRC liver metastases was performed by searching the MEDLINE, Embase, Cancerlit, Cochrane and GoogleScholar electronic databases as well as other databanks collecting information on clinical trials. Inclusion criteria were patients with unresectable CRC liver metastases enrolled in RCT comparing HAI to SCT. The outcome measures were tumor response rate and overall survival. Two authors independently carried out study selection and assessment of methodological quality. A third author performed a concordance analysis in order to unravel potential systematic biases. Ten RCT were identified that met the eligibility criteria. HAI regimens were based on floxuridine (FUDR), 5-fluorouracil or either one of these two fluoropyrimidines in eight and one RCT, respectively. SCT consisted of FUDR or 5-fluorouracil in three and seven RCT, respectively. By pooling the summary data, tumor response rate resulted 42.9% and 18.4% for HAI and SCT, respectively (RR = 2.26; 95% CI, 1.80 to 2.84; P < 0.0001). Mean weighted median OS times were 15.9 and 12.4 months for HAI and SCT, respectively: the meta-risk of death was not statistically different between the two treatment groups (HR = 0.90; 95% CI, 0.76 to 1.07; P = 0.24). Currently available evidence does not support the clinical or investigational use of fluoropyrimidine-based HAI alone for the treatment of patients with unresectable CRC liver metastases: in fact, the greater tumor response rate obtained with this HAI regimen does not translate into a survival advantage over fluoropyrimidine alone SCT.
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Wambaugh, Morgan A; Shakya, Viplendra P S; Lewis, Adam J; Mulvey, Matthew A; Brown, Jessica C S
2017-06-01
Antibiotic-resistant infections kill approximately 23,000 people and cost $20,000,000,000 each year in the United States alone despite the widespread use of small-molecule antimicrobial combination therapy. Antibiotic combinations typically have an additive effect: the efficacy of the combination matches the sum of the efficacies of each antibiotic when used alone. Small molecules can also act synergistically when the efficacy of the combination is greater than the additive efficacy. However, synergistic combinations are rare and have been historically difficult to identify. High-throughput identification of synergistic pairs is limited by the scale of potential combinations: a modest collection of 1,000 small molecules involves 1 million pairwise combinations. Here, we describe a high-throughput method for rapid identification of synergistic small-molecule pairs, the overlap2 method (O2M). O2M extracts patterns from chemical-genetic datasets, which are created when a collection of mutants is grown in the presence of hundreds of different small molecules, producing a precise set of phenotypes induced by each small molecule across the mutant set. The identification of mutants that show the same phenotype when treated with known synergistic molecules allows us to pinpoint additional molecule combinations that also act synergistically. As a proof of concept, we focus on combinations with the antibiotics trimethoprim and sulfamethizole, which had been standard treatment against urinary tract infections until widespread resistance decreased efficacy. Using O2M, we screened a library of 2,000 small molecules and identified several that synergize with the antibiotic trimethoprim and/or sulfamethizole. The most potent of these synergistic interactions is with the antiviral drug azidothymidine (AZT). We then demonstrate that understanding the molecular mechanism underlying small-molecule synergistic interactions allows the rational design of additional combinations that bypass drug resistance. Trimethoprim and sulfamethizole are both folate biosynthesis inhibitors. We find that this activity disrupts nucleotide homeostasis, which blocks DNA replication in the presence of AZT. Building on these data, we show that other small molecules that disrupt nucleotide homeostasis through other mechanisms (hydroxyurea and floxuridine) also act synergistically with AZT. These novel combinations inhibit the growth and virulence of trimethoprim-resistant clinical Escherichia coli and Klebsiella pneumoniae isolates, suggesting that they may be able to be rapidly advanced into clinical use. In sum, we present a generalizable method to screen for novel synergistic combinations, to identify particular mechanisms resulting in synergy, and to use the mechanistic knowledge to rationally design new combinations that bypass drug resistance.
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Lewis, Adam J.; Mulvey, Matthew A.
2017-01-01
Antibiotic-resistant infections kill approximately 23,000 people and cost $20,000,000,000 each year in the United States alone despite the widespread use of small-molecule antimicrobial combination therapy. Antibiotic combinations typically have an additive effect: the efficacy of the combination matches the sum of the efficacies of each antibiotic when used alone. Small molecules can also act synergistically when the efficacy of the combination is greater than the additive efficacy. However, synergistic combinations are rare and have been historically difficult to identify. High-throughput identification of synergistic pairs is limited by the scale of potential combinations: a modest collection of 1,000 small molecules involves 1 million pairwise combinations. Here, we describe a high-throughput method for rapid identification of synergistic small-molecule pairs, the overlap2 method (O2M). O2M extracts patterns from chemical-genetic datasets, which are created when a collection of mutants is grown in the presence of hundreds of different small molecules, producing a precise set of phenotypes induced by each small molecule across the mutant set. The identification of mutants that show the same phenotype when treated with known synergistic molecules allows us to pinpoint additional molecule combinations that also act synergistically. As a proof of concept, we focus on combinations with the antibiotics trimethoprim and sulfamethizole, which had been standard treatment against urinary tract infections until widespread resistance decreased efficacy. Using O2M, we screened a library of 2,000 small molecules and identified several that synergize with the antibiotic trimethoprim and/or sulfamethizole. The most potent of these synergistic interactions is with the antiviral drug azidothymidine (AZT). We then demonstrate that understanding the molecular mechanism underlying small-molecule synergistic interactions allows the rational design of additional combinations that bypass drug resistance. Trimethoprim and sulfamethizole are both folate biosynthesis inhibitors. We find that this activity disrupts nucleotide homeostasis, which blocks DNA replication in the presence of AZT. Building on these data, we show that other small molecules that disrupt nucleotide homeostasis through other mechanisms (hydroxyurea and floxuridine) also act synergistically with AZT. These novel combinations inhibit the growth and virulence of trimethoprim-resistant clinical Escherichia coli and Klebsiella pneumoniae isolates, suggesting that they may be able to be rapidly advanced into clinical use. In sum, we present a generalizable method to screen for novel synergistic combinations, to identify particular mechanisms resulting in synergy, and to use the mechanistic knowledge to rationally design new combinations that bypass drug resistance. PMID:28632788