Thymidine Synthase Research Articles

5-Fluorouracil treatment represses pseudouridine-containing miRNA export into extracellular vesicles.

5-Fluorouracil (5-FU) has been used for chemotherapy for colorectal and other cancers for over 50 years. The prevailing view of its mechanism of action is inhibition of thymidine synthase leading to defects in DNA replication and repair. However, 5-FU is also incorporated into RNA causing defects in RNA metabolism, inhibition of pseudouridine modification, and altered ribosome function. We examined the impact of 5-FU on post-transcriptional small RNA modifications (PTxMs) and the expression and export of RNA into small extracellular vesicles (sEVs). EVs are secreted by all cells and contain a variety of proteins and RNAs that can function in cell-cell communication. We found that treatment of colorectal cancer (CRC) cells with 5-FU represses sEV export of miRNA and snRNA-derived RNAs, but promotes export of snoRNA-derived RNAs. Strikingly, 5-FU treatment significantly decreased the levels of pseudouridine on both cellular and sEV small RNA profiles. In contrast, 5-FU exposure led to increased levels of cellular small RNAs containing a variety of methyl-modified bases. These unexpected findings show that 5-FU exposure leads to altered RNA expression, base modification, and aberrant trafficking and localization of small RNAs.

Metabolic engineering of Escherichia coli for thymidine production

Thymidine, as a crucial precursor of anti-AIDS drugs (e.g., zidovudine and stavudine), has wide application potential in the pharmaceutical industry. In this study, we introduced the thymidine biosynthesis pathway into the wild-type Escherichia coli MG1655 by systems metabolic engineering to improve the thymidine production in E. coli. Firstly, deoA, tdk, udp, rihA, rihB, and rihC were successively deleted to block the thymidine degradation pathway and salvage pathway in the wild-type E. coli MG1655. Then, the pyrimidine nucleoside operons from Bacillus subtilis F126 were introduced to enlarge the metabolic flux of the uridylic acid synthesis pathway. Finally, the expression of uridylate kinase, ribonucleoside diphosphate reductase, thymidine synthase, and 5'-nucleotidase in the thymidine biosynthesis pathway was optimized to enhance the metabolic flux from uridylic acid to thymidine. The engineered THY6-2 strain produced 11.10 g/L thymidine in a 5 L bioreactor with a yield of 0.04 g/g glucose and productivity of 0.23 g/(L·h). In this study, we constructed a strain that used glucose as the only carbon source for efficient production of thymidine and did not harbor plasmids, which provided a reference for the research on other pyrimidine nucleosides.

Capecitabine mitigates cardiac allograft rejection via inhibition of TYMS-Mediated Th1 differentiation in mice

ObjectivesPrevious studies elucidated that capecitabine (CAP) works as an anti-tumor agent with putative immunosuppressive effects. However, the intricate mechanisms underpinning these effects remain to be elucidated. In this study, we aimed to unravel the molecular pathways by which CAP exerts its immunosuppressive effects to reduce allograft rejection. MethodsHearts were transplanted from male BALB/c donors to male C57BL/6 recipients and treated with CAP for seven days. The rejection of these heart transplants was assessed using a range of techniques, including H&E staining, immunohistochemistry, RNA sequencing, LS-MS/MS, and flow cytometry. In vitro, naïve CD4+ T cells were isolated and cultured under Th1 condition medium with varying treatments, flow cytometry, LS-MS/MS were employed to delineate the role of thymidine synthase (TYMS) during Th1 differentiation. ResultsCAP treatment significantly mitigated acute allograft rejection and enhanced graft survival by reducing graft damage, T cell infiltration, and levels of circulating pro-inflammatory cytokines. Additionally, it curtailed CD4+ T cell proliferation and the presence of Th1 cells in the spleen. RNA-seq showed that TYMS, the target of CAP, was robustly increased post-transplantation in splenocytes. In vitro, TYMS and its metabolic product dTMP were differentially expressed in Th0 and Th1, and were required after activation of CD4+ T cell and Th1 differentiation. TYMS-specific inhibitor, raltitrexed, and the metabolite of capecitabine, 5-fluorouracil, could inhibit the proliferation and differentiation of Th1. Finally, the combined use of CAP and the commonly used immunosuppressant rapamycin can induce long-term survival of allograft. ConclusionCAP undergoes metabolism conversion to interfere pyrimidine metabolism, which targets TYMS-mediated differentiation of Th1, thereby playing a significant role in mitigating acute cardiac allograft rejection in murine models.

Green Chemistry and In silico Techniques for Synthesis of Novel Pyranopyrazole and Pyrazolo-pyrano-pyrimidine Derivatives as Promising Antifungal Agents.

Every year Invasive Fungal Infections (IFI) are globally affecting millions of people. Candida albicans and Aspergillus niger have been reported as the most infectious and mortality-inducing fungal strains among all pathogenic fungi. To tackle this problem in the current study Pyranopyrazoles and Pyrazolopyrano- pyrimidine derivatives were developed using molecular hybridization, green chemistry and one-pot multicomponent reaction. In the present work, New Chemical entities (NCE's) were developed on the basis of Structure activity relationship. All designed NCE's were screened for ADMET studies using the QikProp module of Schrodinger software. NCE's with zero violations were further docked on the crystal structure of 14α demethylase, cytochrome P450 and thymidine synthase (PDB ID: 5V5Z, 7SHI, 1BID). Selected molecules were synthesized using green chemistry techniques and evaluated for in vitro antifungal activity against Candida albicans and Aspergillus niger. Designed NCE's (B1-12 and C1-11) showed favorable results in ADMET studies. In the docking study six compounds from series-B and five molecules from series- C showed good dock score and binding interaction when compared with the standard drugs. Compounds B-3 and C-4 showed the highest zone of inhibition activity against Candida albicans, where as B-1 and C-3 had shown highest zone of inhibition activity against Aspergillus niger. Bicyclic ring (series B) showed better activity as compare to fused tricyclic ring (series C).

Tackling Antibiotic Resistance: Exploring 5-Fluorouracil as a Promising Antimicrobial Strategy for the Treatment of Streptococcus suis Infection.

Streptococcus suis (S. suis) is a zoonotic pathogen with a global distribution, which causes serious diseases in both humans and animals and economic losses in the swine industry. As antibiotic resistance increases, there is an urgent imperative to explore novel antibacterial alternatives. In the present study, we selected the anticancer drug 5-fluorouracil (5-FU) approved by the Food and Drug Administration (FDA) as a candidate drug to treat S. suis infections. The results showed that various pathogens, especially S. suis, are more sensitive to 5-FU. Moreover, the cytotoxicity of 5-FU is relatively low. Extensive in vitro assays demonstrated the pronounced bacteriostatic and bactericidal efficacy of 5-FU against susceptible and multidrug-resistant S. suis strains. Its mechanisms of action include damage to the bacterial cell walls and membranes, resulting in the leakage of intracellular components, and the inhibition of thymidylate synthase (TS), leading to a depletion of deoxythymidine triphosphate (dTTP) pools, ultimately causing thymine-less death and lethal DNA damage in bacteria. Gene-knockout experiments further showed that 5-FU played a role by inhibiting the thyA gene-encoding thymidine synthase. Finally, we determined that S. suis infections can be alleviated by 5-FU in the mouse infection model. This study emphasizes the antibacterial potential of 5-FU against S. suis and provides evidence for its targeting of bacterial membrane damage and DNA damage. In summary, 5-FU can control S. suis infection and is expected to become a new alternative to antibiotics.

Regioisomerization of Antimalarial Drug WR99210 Explains the Inactivity of a Commercial Stock.

WR99210, a former antimalarial drug candidate now widely used for the selection of Plasmodium transfectants, selectively targets the parasite's dihydrofolate reductase thymidine synthase bifunctional enzyme (DHFR-TS) but not human DHFR, which is not fused with TS. Accordingly, WR99210 and plasmids expressing the human dhfr gene have become valued tools for the genetic modification of parasites in the laboratory. Concerns over the ineffectiveness of WR99210 from some sources encouraged us to investigate the biological and chemical differences of supplies from two different companies (compounds 1 and 2). Compound 1 proved effective at low nanomolar concentrations against Plasmodium falciparum parasites, whereas compound 2 was ineffective, even at micromolar concentrations. Intact and fragmented mass spectra indicated identical molecular formulae of the unprotonated (free base) structures of compounds 1 and 2; however, the compounds displayed differences by thin-layer chromatography, reverse-phase high-performance liquid chromatography, and UV-visible spectroscopy, indicating important isomeric differences. Structural evaluations by 1H, 13C, and 15N nuclear magnetic resonance spectroscopy confirmed compound 1 as WR99210 and compound 2 as a dihydrotriazine regioisomer. Induced fit computational docking models showed that compound 1 binds tightly and specifically in the P. falciparum DHFR active site, whereas compound 2 fits poorly to the active site in loose and varied orientations. Stocks and concentrates of WR99210 should be monitored for the presence of regioisomer 2, particularly when they are not supplied as the hydrochloride salt or are exposed to basic conditions that may promote rearrangement. Absorption spectroscopy can serve for assays of the unrearranged and rearranged triazines.

Multiple-targets Directed Screening of Flavonoid Compounds from Citrus Species to find out Antimalarial Lead with Predicted Mode of Action: An In Silico and Whole Cell-based In vitro Approach.

Development of resistance by the malaria parasite Plasmodium falciparum has created challenges in the eradication of this deadly infectious disease. Hence newer strategies are adopted to combat this disease and simultaneously, new lead/hit identification is going on worldwide to develop new chemotherapeutic agents against malaria. In this study, 44 flavonoids found mainly in the fruit juice of Citrus species having traditional use in malaria-associated fever were selected for in silico multiple-target directed screening against three vital targets of the parasite namely dihydroorotate dehydrogenase (PfDHODH), dihydrofolate reductase thymidine synthase (PfDHFR-TS) and plasma membrane P-type cation translocating ATPase (PfATP4) to find out new lead molecule(s). The in silico screening was carried out using different protocols of the Biovia Discovery Studio 2018 software and Network analyzer plugin of Cytoscape 3.6.0 followed by in vitro screening of the best lead. After screening, CF8 or luteolin was found to have good binding affinity against PfDHODH and PfATP4 with -CDocker energy 42.2719 and 33.1447 with respect to their cocrystal ligands. These findings were also supported by structure-based pharmacophore, DFT (Density Functional Theory) study and finally by in vitro screening of the lead with IC50 values of 8.23 μm and 12.41 μm against 3D7 (chloroquine-sensitive) and RKL-9 (chloroquine-resistant) strain of P. falciparum, respectively. Our study found a moderately active lead molecule with the predicted mode of action which can be utilized to design some new derivatives with more safety and efficacy by targeting the two enzymes.

Lauric acid induce cell death in colon cancer cells mediated by the epidermal growth factor receptor downregulation: An in silico and in vitro study.

Coconut oil (CO) is enriched with medium chain saturated fatty acids like lauric acid (LA), capric acid and caprylic acid, which are known to have several health benefits. LA, the predominant fatty acid in CO, is reported to possess anticancer activity mediated through oxidative stress-induced apoptosis; however, there is no clear information on its cellular signalling mechanism. The present study screened the anticancer potential of various fatty acids present in CO (capric acid, caprylic acid and LA) using in silico tools such as CDOCKER in Accelrys Discovery Studio by targeting proteins like epidermal growth factor receptor (EGFR), cyclin-dependent kinase and thymidine synthase (TS). The results were further confirmed using cell culture-based studies and quantitative PCR. Among the tested compounds, LA was found to be the most active and showed a higher affinity towards EGFR and TS. Corroborating with these results, LA-induced dose-dependent cytotoxicity towards HCT-15 (human colon cancer), HepG2 (human hepatocellular carcinoma) and Raw 264.7 (murine macrophages) cells exhibiting morphological characteristics of apoptosis. Further, in HCT-15 cells exposed to LA (30 and 50 µg/mL), the expression of EGFR was found to be downregulated by 1.33- and 1.58-fold. The study thus concludes that the anticancer activity of LA may be partially mediated by the downregulation of EGFR signalling and consequent reduction in cell viability through apoptosis. Since EGFR signalling is crucial in cancer cell survival and is a prime target in drug development, the present study has pharmacological significance.

Abstract OT1-05-01: A pilot study of the combination of entinostat with capecitabine in metastatic and high risk breast cancer after neoadjuvant therapy

Abstract Background: HDAC inhibitors (HDACi) upregulate thymidine phosphorylase resulting in enhanced conversion of capecitabine to active 5-fluorouracil and in synergistic anti-proliferative effects. HDACi's down regulate thymidine synthase and may prevent resistance to fluoropyrimidines. Entinostat is a well-tolerated class I HDACi in phase III trials for metastatic breast cancer. Specific Aims: The primary objective is to determine the maximum tolerated dose combination (MTDC) of entinostat and capecitabine in participants with metastatic breast cancer. It is hypothesized that entinostat and capecitabine is a synergistic, safe, and tolerable combination. An expansion phase will assess the safety of the MTDC from Part A in participants with high risk breast cancer after neoadjuvant therapy. The expansion phase will generate a preliminary estimate of disease-free survival. Exploratory objectives include estimates of the association of volume of circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs) with the presence of residual disease and if it decreases following treatment with the combination of entinostat and capecitabine. Trial Design: The dose escalation phase (Part A) will accrue participants with metastatic breast cancer using an adaptive design to determine the MTDC. The starting doses will be entinostat 3mg po weekly and capecitabine 800mg/m2 po bid, 14 days on and 7 days off with 21 day cycles. Patients will be monitored for toxicity and adverse events. The MTDC is defined as the dose combination with DLT rate closest to the target DLT rate of 25%. The expansion phase (Part B) will accrue breast cancer participants with residual invasive disease after neoadjuvant therapy starting at the MTDC estimated in Part A. The adaptive modeling design will be used in Part B to establish the MTDC in this patient population. Participants will be treated with the MTDC for a total of 8 cycles. Blood samples will be obtained from all enrolled patients in the expansion phase prior to the start of adjuvant treatment with entinostat and capecitabine so that ctDNA and CTCs can be measured as correlative studies. Measurements will be repeated at the end of the eighth cycle. Eligibility Criteria: Part A: Dose Escalation Phase: Stage IV breast cancer patients; Receptor Status: hormone receptor positive or negative, triple negative patients; Age: 18 year and older Part B: Expansion Phase: Stage I-III high risk breast cancer patients; Completed at least four cycles of neoadjuvant taxane or anthracycline based chemotherapy; Residual invasive disease (ypT1a or greater) or known positive lymph nodes (ypN0(itc) or greater); Receptor Status: hormone receptor positive or negative, triple negative patients; Age: 18 years and older Statistical Methods: The trial is designed to determine the MTDC, defined by acceptable toxicity of the combination, for two study populations. A Bayesian adaptive design is being used to guide accrual decisions based on the occurrence of DLTs, and the minimum follow-up period for determination of escalation is 3 weeks. Accrual: Maximum target accrual is 55 participants. Accrual is estimated at 1-2 participants per month. Contact Info: Trish Millard, MD tas9g@virginia.edu Citation Format: Millard TA, Wages NA, Petroni GR, Brenin CM, Dillon PM. A pilot study of the combination of entinostat with capecitabine in metastatic and high risk breast cancer after neoadjuvant therapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT1-05-01.

Corosolic acid reduces 5‑FU chemoresistance in human gastric cancer cells by activating AMPK.

5-Fluorouracil (5-FU) is one of the most commonly used chemotherapeutic agents for gastric cancer. Resistance to 5-FU-based chemotherapy remains the major obstacle in the treatment of gastric cancer. A growing body of evidence has suggested that adenosine monophosphate-activated protein kinase (AMPK) is pivotal for chemoresistance. However, the mechanism by which AMPK regulates the chemosensitivity of gastric cancer remains unclear. In the present study, how corosolic acid enhanced the chemosensitivity of gastric cancer cells to 5-FU via AMPK activation was investigated. A 5-FU-resistant gastric cancer cell line (SNU-620/5-FUR) was established, which had a marked increase in thymidine synthase (TS) expression but reduced AMPK phosphorylation when compared with the parental cell line, SNU-620. AMPK regulation by 5-aminoimidazole-4-carboxamide ribonucleotide or compound c was revealed to be markedly associated with TS expression and 5-FU-resistant cell viability. In addition, corosolic acid activated AMPK, and decreased TS expression and the phosphorylation of mammalian target of rapamycin/4E-binding protein 1 in a dose-dependent manner. Corosolic acid treatment significantly reduced cell viability while compound c reversed corosolic acid-induced cell growth inhibition. The 5-FU-resistance sensitization effect of corosolic acid was determined by the synergistic reduction of TS expression and inhibition of cell viability in the presence of 5-FU. The corosolic acid-induced AMPK activation was markedly increased by additional 5-FU treatment, while compound c reversed AMPK phosphorylation. In addition, compound c treatment reversed corosolic acid-induced apoptotic markers such as capase-3 and PARP cleavage, and cytochrome c translocation to cytosol, in the presence of 5-FU. Corosolic acid treatment in the presence of 5-FU induced an increase in the apoptotic cell population based on flow cytometry analysis. This increase was abolished by compound c. In conclusion, these results implied that corosolic acid may have therapeutic potential to sensitize the resistance of gastric cancer to 5-FU by activating AMPK.

Abstract 2318: Palbociclib, a CDK4/6 inhibitor, suppresses proliferation of triple negative breast cancer

Abstract Background: Abnormal cell cycle progression is a characteristic of cancer and targeting the cell cycle is a strategy for cancer treatment. TCGA reported that Cyclin D1 is overexpressed in 25% to 60% of invasive breast carcinomas, and CDK4/6 and CDKN2A/B aberrations are observed in 7.6% of breast cancer cases. Palbociclib is a specific inhibitor of CDK4/6, a key regulator of the G1 checkpoint. In hormone receptor positive breast cancer, the addition of palbociclib to endocrine treatment either aromatase inhibitor or fulvestrant significantly prolonged PFS in phase III trials. However, the effects of palbociclib have not been fully examined in triple negative breast cancer (TNBC) yet, although CCND amplification and CDKN2A loss are frequently observed in TNBC. Therefore, we investigated the effects of palbociclib on TNBC cells and attempted to identify the underlying mechanisms of palbociclib. Methods: The cytotoxicity assay, cell cycle analysis and western blotting were conducted to determine anti-tumor effect and action mechanisms of palbociclib on breast cancer cell lines. These in vitro data were validated in vivo model as well. Results: Human breast cancer cell lines showed heterogeneous response to palbociclib. Palbociclib induced G1 cell cycle arrest by blocking Rb phosphorylation, and inhibited cell proliferative signaling. In sensitive TNBC cells, palbociclib promoted senescence rather than apoptosis. In addition, palbociclib enhanced the antitumor effect of 5-FU by modulating thymidine synthase (TS) and E2F1 expression. The anti-tumor effects of palbociclib on TNBC cells were validated in TNBC-xenograft model as well. Conclusions: CDK4/6 inhibitor palbociclib showed anti-tumor effect in vitro and in vivo xenograft model of TNBC and acts synergistically with 5-FU by downregulating TS. Our results suggest that palbociclib has therapeutic potential for the treatment of TNBC, not limited in hormone positive breast cancer type. Our results provide a rationale for the future clinical trials of palbociclib in the treatment of breast cancers. Citation Format: Ahrum Min, Yu Jin Kim, Hyemin Hang, Jee Min Lim, Seongyeong Kim, So Hyeon Kim, Koung Jin Suh, Kyung-Hun Lee, Tae-Yong Kim, Seock-Ah Im. Palbociclib, a CDK4/6 inhibitor, suppresses proliferation of triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2318.

Abstract 1867: Combined and sequential chemotherapy efficacy of trifluridine/tipiracil and regorafenib in colorectal cancer cell lines

Abstract Background: Trifluridine/tipiracil (FTD/TPI or TFTD, also known as TAS-102) is recommended for treating metastatic colorectal cancers refractory to standard chemotherapies. Regorafenib is an oral multikinase inhibitor that blocks the activity of several protein kinases associated with angiogenesis, oncogenesis, and the tumor microenvironment. We evaluated the antitumor effects of FTD/TPI combined with regorafenib on a colorectal tumor xenograft mouse model. We also investigated whether cytotoxicity was enhanced when FTD was used sequentially with regorafenib in vitro. Method: The colorectal cancer cell lines SW620 and COLO 205 were implanted into nude mice subcutaneously. FTD/TPI (150 mg/kg/day) was orally administered twice daily from days 1 to 14 and regorafenib (10 mg/kg/day) was administered once a day at approximately 2-4 h after FTD/TPI. For the in vitro cytotoxic assay, SW620 cells were treated with FTD and regorafenib as follows: (1) exposure to 0.1-4.0 µM FTD alone, (2) sequential exposure to 0.1-4.0 µM FTD for 24 h followed by 10 µM regorafenib for 24 h, or (3) sequential exposure to 10 µM regorafenib for 24 h followed by 0.1-4.0 µM FTD for 24 h. All treatments were evaluated by a colony formation assay. Molecules involved in mechanism of action of FTD and regorafenib and in apoptosis were evaluated by western blot. Results: Tumor growth inhibition by combination therapy was 86.4% and 92.3% for SW620 and COLO 205 xenografts, respectively; this was significantly superior to the growth inhibition observed after either monotherapy for the two evaluated cancer xenografts (P < 0.01). Thus, FTD/TPI combined with regorafenib is significantly more effective than either monotherapy in colorectal cancer xenografts. This combination therapy was tolerated without 20% body-weight reduction and drug-related death. FTD followed by regorafenib treatment in SW620 cells showed stronger cell killing effect than FTD alone. In contrast, regorafenib followed by FTD treatment attenuated its cell killing effect rather than that to FTD alone. In comparison with FTD alone, FTD followed by regorafenib reduced thymidine synthase (TS) and inhibited phosphorylation of ERK1/2 (pERK1/2) with the induction of proapoptotic marker, cleavage of PARP. In contrast, regorafenib followed by FTD induced TS and pERK1/2. Thus, FTD followed by regorafenib treatment is more effective than regorafenib followed by FTD treatment in vitro. Conclusion: FTD/TPI combined with regorafenib is significantly more effective than either monotherapy in preclinical models. Moreover, FTD followed by regorafenib is more effective than vice versa in vitro, suggesting that in patients sequential therapy with FTD/TPI prior to regorafenib may be helpful in treating colorectal cancer. Citation Format: Kazuaki Matsuoka, Fumio Nakagawa, Junji Uchida, Teiji Takechi. Combined and sequential chemotherapy efficacy of trifluridine/tipiracil and regorafenib in colorectal cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1867.

Cyclin E overexpression confers resistance to the CDK4/6 specific inhibitor palbociclib in gastric cancer cells

Palbociclib is a specific inhibitor of CDK4/6 and has been shown to provide a survival benefit in hormone receptor-positive advanced breast cancer. TCGA database reported that about half of gastric cancers exhibit abnormalities in cell-cycle-related molecules, suggesting that gastric cancer is a good candidate for palbociclib treatment; however, the antitumor effects and predictive markers of palbociclib in gastric cancer remain incompletely described. Herein, the effect and predictive markers of palbociclib on gastric cancer cells were investigated. Our results reveal that palbociclib showed anti-proliferative effects by inducing G1 phase cell-cycle arrest and cellular senescence in some gastric cancer cells. Basal protein expression level of cyclin E showed an inverse correlation of cancer cell sensitivity to palbociclib. In addition, palbociclib enhanced the antitumor effect of 5-FU in vitro and in vivo by modulating thymidine synthase expression. These results suggest that cyclin E protein expression determines the anti-proliferative effect of palbociclib, and palbociclib acts synergistically with 5-FU in gastric cancer. These findings provide a rationale for future clinical trials of palbociclib and 5-FU combination-based chemotherapy in gastric cancer.

Histological analysis of anti-cancer drug loaded, targeted Mn:ZnS quantum dots in metastatic lesions of 4T1 challenged mice.

5-Fluororaucil (5-FU) as anti-cancer drug was reported to induce thymidine synthase (TS) overexpression and cancer cell resistance. To improve its therapeutic efficacy and selective targeting, here we developed a targeted delivery system mediated by the active ligand-folate receptor chemistry to deliver the 5-FU drug selectively into the tumor microenvironment. The preparation was achieved by exploring chitosan (CS)-biopolymer based system with folic acid (FA)-conjugation. The 5-FU@FACS-Mn:ZnS quantum dots (QDs) based on the histological assessment conducted in the 4T1 challenged mice showed an improved tumor remission in the liver, spleen and lungs. The 5-FU@FACS-Mn:ZnS composite induced anti-proliferative properties in these organs as compared to the free 5-FU drug. Unlike the 5-FU@FACS-Mn:ZnS treated groups which showed some specific morphological changes such as cell shrinkage without obvious presence of adipocytes, the excised section of the tumor in the untreated control group and the free 5-FU drug treated group showed necrotic and degenerated cells; these cells are multifocally distributed in the tumor mass with evidence of widely distributed adipocytes within the tumor mass. These findings suggest that the 5-FU@FACS-Mn:ZnS composite has a superior role during the induction of apoptosis in the 4T1 cells as compared to the free 5-FU drug treated groups. The results of the study therefore suggest that the impregnation of 5-FU anti-cancer drug within the FACS-Mn:ZnS system significantly improves its selective targeting efficacy, in addition to improving the anti-proliferative properties and attenuate possible tumor resistances to the 5-FU drug. The work discusses about the anti-metastatic effects of folic acid-bound 5-Fluororacil loaded Mn:ZnS quantum dots towards 4T1 cell line proliferation in mice based on the histological analysis.

Phase I/IB multicenter study of afatinib in combination with capecitabine in patients (pts) with refractory solid tumors and pancreatico-biliary cancers.

TPS515 Background: The epidermal growth factor receptor (EGFR)/HER2 pathway is overactive in several solid tumors, including gastroesophageal, hepatic, colorectal, and pancreatico-biliary cancers. Afatinib is an irreversible inhibitor of the Erb family approved for metastatic non-small cell lung cancer with EGFR mutations. Afatinib downregulates thymidine synthase (TS) the intracellular target of fluoropyrimidine chemotherapy such as capecitabine. Treatment of colorectal cancer cell lines with cytotoxic drugs can up-regulate EGFR expression, and increase sensitivity to EGFR inhibition. Based on this preclinical rationale, and given that capecitabine is commonly used in refractory gastrointestinal cancers, we have developed a phase I/Ib trial to evaluate the safety and maximum tolerated dose (MTD) of afatinib with capecitabine in advanced solid tumors, and assess preliminary antitumor activity in pts with refractory pancreatico-biliary cancers at MTD. Methods: Eligible pts have metastatic solid tumors (phase I) or pancreatico-biliary cancers (phase Ib), ECOG PS 0-2 (PS 0-1 phase Ib), any number of prior therapies (phase I), or ≤ 2 prior therapies (phase Ib), no prior erlotinib (phase Ib), and have archived paraffin embedded tumor tissue, or ability to undergo tumor biopsy at baseline. Tumor tissue is analyzed with UW-OncoPlex, a multiplexed gene sequencing panel of 200+ cancer-related genes, to identify predictive biomarkers of benefit. The study design is standard “3+3”. Afatinib is administered orally (PO) daily (QD) in escalating doses of 20, 30 and 40 mg, with capecitabine at 1000 mg/m2 PO BID Days 1-14, in 21-day cycles (C). Dose limiting toxicity (DLT) is assessed in C1. Once the MTD is identified, the phase Ib expansion cohorts will enroll 15 pts each with refractory pancreatic and biliary cancers, with afatinib dosed at MTD and standard dose capecitabine. The study was activated in November 2015, and to date 4 pts were enrolled in cohort 1, 3 pts in cohort 2, and 2 pts in cohort 3. The phase I is ongoing and the phase Ib is expected to start enrollment in December 2016. Clinical trial information: NCT02451553.

SC05.02 Novel Cytotoxic Drugs in Lung Cancer

Even in the era of precision medicine and immunotherapy, cytotoxic chemotherapies remain an essential component of lung cancer treatment, both in resectable disease as well as in advanced/metastatic lung cancer. We have chosen to focus on 2 new cytotoxic compounds, which are likely to emerge as new players in the field of lung cancer management. One (named PM1183) has activity in small-cell lung cancer (SCLC), the other TAS-114 has activity in non-small cell lung cancer (NSCLC). PM1183 is a DNA-binding chemotherapy with a new mechanism of action. PM1183 acts as an inhibitor of transcription. Binding of PM1183 to CG-rich motifs, triggers sequential phosphorylation of Pol II and stalling of elongating Pol II. This leads to recruitment of the ubiquitin-proteasome machinery, RNA Pol II degradation, and recruitment of XPF, generation of DNA breaks and induction of apoptosis. PM1183 has been tested in a phase IB trial in combination with doxorubicine. In the dose-finding part: recommended dose (RD) was defined at PM1183 4.0 mg flat dose (FD) or 2.0 mg/m2 + DOX 50 mg/m2 both on day (D)1 every three weeks (q3w). Myelosuppression was dose-limiting (DLT). Compelling activity was observed during escalation phase. It was especially remarkable as 2nd line in SCLC patients: 5 of 7 evaluable pts (71%) had objective partial response (PR) as per RECIST v.1.1. In an expansion cohort of 20 patients, PM1183 and DOX showed outstanding clinical activity: 67% response rate, including 10% of CRs, as 2nd line treatment in SCLC patients. A randomized phase III trial testing PM1183 + DOX is planned and will compare this combination with topotecan or CAV. TAS-114 is a first-in-class oral deoxyuridine triphosphatase (dUTPase) inhibitor that acts as a modulator of the pyrimidine nucleotide metabolic pathway by blocking the conversion of 2’-deoxyuridine-5’-triphosphate (dUTP; FdUTP) into 2’-deoxyuridine-5’-monophophate (dUMP; FdUMP) through reversible inhibition of dUTPase (gatekeeper protein), resulting in the enhanced incorporation of both uracil and fluorouracil into DNA. The activity of TAS-114, administered in combination with thymidine synthase (TS) inhibitors, 5-FU, S-1 or capecitabine, has been studied pre-clinically in various cancer cell lines and animal models. TAS-114 selectively inhibited dUTPase and showed a higher affinity than the substrates of dUTPase, dUTP and FdUTP, inhibition constant values of TAS-114 were 0.13 μM and 0.10 μM, respectively. The antitumor effect of TAS-114 combined with S-1 as compared to that of S-1 alone was investigated in vivo using a xenograft mouse model with NCI-H2228 (human NSCLC). Both regimens were administered orally (TAS-114: 600 mg/kg/day and S-1: 8.3 mg/kg/day vs S-1: 8.3 mg/kg/day through day 1 to 28) and resulted in relative tumor volumes of 1.61% vs 3.04%, p<0.01, inhibition rates of 52.7% vs 10.8%, and body weight changes of 6.8% vs 3.3%, respectively. A phase 1 clinical study of TAS-114 and S-1 combination treatment is currently ongoing to investigate the safety and to determine the maximum-tolerated dose (MTD) and recommended dose (RD) in patients (pts) with advanced refractory solid tumors. TAS-114 and S-1 are administrated orally twice a day for 14 days followed by 7 days resting period for a 21-days cycle at the starting dosage of 5 mg/m2 with the fixed dosage of 25 mg/m2, respectively. To date, a total of 96 pts were enrolled with 37 pts in the dose escalation and 59 pts in the MTD expansion stages. TAS-114 and S-1 were escalated up to 240 mg/m2 and 36 mg/m2, respectively, with 2 DLTs observed at the highest dose level (1 patient with G3 rash and 1 patient with G2 rash/G2 HFS), therefore TAS-114 at 240 mg/m2 and S-1 at 30 mg/m2 was determined to be the MTD and RD. The most common treatment related adverse events were anemia and rash. There were 4 confirmed partial responses observed in 2 non-small cell lung (NSCLC) pts, 1 pancreas pt and 1 colorectal cancer patient to date. Amongst 6 evaluable NSCLC pts to date, there was an overall response rate of 33% (2/6) with 2 confirmed PR and a disease control rate of 100% (6/6). Pharmacodynamics analysis performed on patient tumor specimens treated at MTD indicated TAS-114 target engagement by reductions in the amount of intra-tumoral dUMP, a “surrogate” metabolite indicative of dUTPase inhibition, following TAS-114/S-1 combination as compared to S-1 alone administration. When TAS-114 is administered in combination with S-1, an additional cytocidal antitumor effect to TTP depletion by TS inhibition is expected as TAS-114 inhibits a gatekeeper protein, thereby allowing increased DNA incorporation of both uracil and 5-FU resulting in DNA damage. new cytotoxics, small-cell lung cancer, non-small cell lung cancer

Tumor 5-FU-related mRNA Expression and Efficacy of Oral Fluoropyrimidines in Adjuvant Chemotherapy of Colorectal Cancer.

It has not been elucidated whether the clinical efficacy of oral fluoropyrimidines for adjuvant chemotherapy of colorectal cancer varies with tumor biological characteristics. A multicenter randomized trial was performed comparing oral tegafur/gimeracil/oteracil (S-1) and uracil-tegafur/ leucovorin (UFT/LV) as adjuvant therapy for stage III colorectal cancer. Postoperative survival was compared based on the 5-FU-related mRNA levels in cancer tissues. Among patients with tumor expressing dihydropyrimidine dehydrogenase (DPD) mRNA within the 66.7th percentile (lower 2/3) of all cases, overall survival (OS) was significantly better in the S-1 than in the UFT/LV group. In the S-1 group, patients with low DPD-expressing tumors had significantly better OS than those with highly expressing tumors. Patients with low thymidine synthase (TS)-expressing tumors had significantly better OS than those with highly expressing tumors. The efficacy of oral fluoropyrimidines as adjuvant chemotherapy for colorectal cancer may be influenced by the level of 5-FU-related mRNA in cancer tissues.

Folic Acid-Metabolizing Enzymes Regulate the Antitumor Effect of 5-Fluoro-2'-Deoxyuridine in Colorectal Cancer Cell Lines.

In colorectal cancer chemotherapy, the current standard of care includes combination therapy with 5-fluorouracil (5-FU) and leucovorin (LV). However, the factors that determine the LV-mediated enhancement of 5-FU antitumor activity are not fully understood. Therefore, we investigated the roles of thymidine synthase (TYMS), folate receptor 1 (FOLR1), dihydrofolate reductase (DHFR), phosphoribosylglycinamide formyltransferase (GART), methylenetetrahydrofolate dehydrogenase (MTHFD1), and methylenetetrahydrofolate reductase (MTHFR) in LV-mediated enhancement of 5-fluoro-2′-deoxyuridine (FdUrd) cytotoxicity in vitro as a model of 5-FU antitumor activity. These genes were downregulated in DLD-1 and HCT116 human colorectal cancer cells by using small-interfering RNA. Reduced expression of TYMS mRNA significantly increased FdUrd cytotoxicity by 100- and 8.3-fold in DLD-1 and HCT116 cells, respectively. In contrast, reducing the expression of FOLR1, DHFR, GART, MTHFD1, and MTHFR decreased FdUrd cytotoxicity by 2.13- to 12.91-fold in DLD-1 cells and by 3.52- to 10.36-fold in HCT116 cells. These results demonstrate that folate metabolism is important for the efficacy of FdUrd. Overall, the results indicate that it is important to clarify the relationship between folate metabolism-related molecules and 5-FU treatment in order to improve predictions of the effectiveness of 5-FU and LV combination therapy.

Correlation between S-1 treatment outcome and expression of biomarkers for refractory thymic carcinoma.

BackgroundThymic carcinoma is a rare cancer with minimal evidence of a survival benefit following chemotherapy. An oral fluoropyrimidine of S-1, however, is the recommended active cytotoxic chemotherapy agent for refractory thymic carcinoma based on a case series, whereas sunitinib or everolimus are recommended as molecular-targeted agents based on Phase II trials. We retrospectively investigated the efficacy of S-1 for refractory thymic carcinoma and performed a biomarker analysis.MethodsWe assessed the clinicopathological variables of 14 consecutive patients who underwent S-1 for refractory thymic carcinoma and correlated the clinical outcomes with potential biomarkers using paraffin-embedded cancer tissues of eight patients in the cohort.ResultsA total of 178 thymic malignancies were identified, of whom 14 patients included 12 cases of squamous cell carcinoma, one lymphoepithelioma-like carcinoma, and one undifferentiated carcinoma. Six patients exhibited a partial response (42.9 %: 95 % confidence interval [CI], 21.4–67.4) and the disease control rate was 85.7 % (60.0–96.0 %). After a median follow-up of 24.2 months, the median progression-free survival was 8.1 months (range, 2.6–12.2 months), and median overall survival was 30.0 months (range, 6.2–41.9 months). No significant correlation between biomarker expression and response was noted. However, thymidine synthase (TS)/dihydropyrimidine dehydrogenase and TS/orotate phosphoribosyltransferase were observed.ConclusionsS-1 for refractory thymic carcinoma offered clinical activity and achieved an 85 % disease control rate. Although the biomarkers did not correlate with clinical outcome, the study results showed efficacy of S-1 as a cytotoxic chemotherapy for refractory thymic carcinoma, which warrants future investigation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2159-7) contains supplementary material, which is available to authorized users.

Combination Treatment of Renal Cell Carcinoma with Belinostat and 5-Fluorouracil: A Role for Oxidative Stress Induced DNA Damage and HSP90 Regulated Thymidine Synthase

Despite several therapeutic options renal cell carcinoma is associated with a poor clinical outcome. Therefore, we investigated whether combining 5-fluorouracil with the histone deacetylase inhibitor belinostat would exert a synergistic effect on renal cell carcinoma cells invitro and invivo. We used SN12C cells treated with 5-fluorouracil and/or belinostat invitro and in xenograft experiments invivo. Cell viability and death mechanisms were assessed by MTS assay and Western blot. To investigate the role of reactive oxygen species we used H2DCF-DA, reactive oxygen species scavengers and the roGFP2 construct. Belinostat potentiated the anticancer effect of 5-fluorouracil. It synergistically induced apoptosis by activating caspases and increasing the subG1 cell population. Effects on reactive oxygen species mediated DNA damage included decreased thioredoxin expression and increased levels of TBP-2, γ-H2AX and Ac-H3. Furthermore, belinostat attenuated the 5-fluorouracil mediated induction of thymidylate synthase via HSP90 hyperacetylation. Co-administration of 5-fluorouracil with belinostat similarly reduced tumor volume and weight, and increased γ-H2AX and Ac-H3 levels in the SN12C xenograft model. In combination with 5-fluorouracil the targeted inhibitor of histone deacetylase synergistically inhibited renal cancer cell growth by the blockade of thymidylate synthase induction and the induction of reactive oxygen species mediated DNA damage invitro and invivo. Our results suggest that combined treatment with belinostat and 5-fluorouracil may represent a promising new approach to renal cancer.