Thymidine Phosphorylase Inhibitor Research Articles

Lysosomal dysfunction and overload of nucleosides in thymidine phosphorylase deficiency of MNGIE

Inherited deficiency of thymidine phosphorylase (TP), encoded by TYMP, leads to a rare disease with multiple mitochondrial DNA (mtDNA) abnormalities, mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). However, the impact of TP deficiency on lysosomes remains unclear, which are important for mitochondrial quality control and nucleic acid metabolism. Muscle biopsy tissue and skin fibroblasts from MNGIE patients, patients with m.3243 A > G mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and healthy controls (HC) were collected to perform mitochondrial and lysosomal functional analyses. In addition to mtDNA abnormalities, compared to controls distinctively reduced expression of LAMP1 and increased mitochondrial content were detected in the muscle tissue of MNGIE patients. Skin fibroblasts from MNGIE patients showed decreased expression of LAMP2, lowered lysosomal acidity, reduced enzyme activity and impaired protein degradation ability. TYMP knockout or TP inhibition in cells can also induce the similar lysosomal dysfunction. Using lysosome immunoprecipitation (Lyso- IP), increased mitochondrial proteins, decreased vesicular proteins and V-ATPase enzymes, and accumulation of various nucleosides were detected in lysosomes with TP deficiency. Treatment of cells with high concentrations of dThd and dUrd also triggers lysosomal dysfunction and disruption of mitochondrial homeostasis. Therefore, the results provided evidence that TP deficiency leads to nucleoside accumulation in lysosomes and lysosomal dysfunction, revealing the widespread disruption of organelles underlying MNGIE.Graphical

Abstract 12759: Thymidine Phosphorylase Enhances SARS-CoV-2 Spike Protein and Platelet Factor 4 Complex Formation: A Potential Novel Mechanism That May Account for COVID-19-Associated Thrombosis

Introduction: Scattered studies suggest that SARS-CoV-2 spike protein (SP) promotes platelet activation, though the exact mechanism is unknown. Thymidine phosphorylase (TYMP), which facilitates platelet activation and thrombosis, is significantly increased in the plasma and lungs of COVID-19 patients, suggesting that TYMP may play a role in the COVID-19 milieu. Hypothesis: We hypothesize that TYMP enhances SP/platelet factor 4 (PF4) complex formation and inhibition of TYMP attenuates SP-induced thrombosis and/or inflammation. Methods: BEAS-2B cells were treated with SP- or its receptor binding domain (RBD)-containing COS-7 cell lysate, or control cell lysate (p3.1) and TYMP and STAT3 expression were determined by western blot. The effect of SP on thrombosis was examined in K18-hACE2 and K18-hACE2/ Tymp -/- mice using the ferric chloride-induced carotid artery injury thrombosis model. SP-, TYMP-, or PF4-encoding plasmids were co-transfected into COS-7 and their protein interactions were assessed using co-IP, Blue Native-PAGE, and immunocytochemistry. Results: SP increased expression of TYMP and pY705-STAT3 in BEAS-2B. siRNA-mediated knockdown of TYMP reduced STAT3 activation. SP significantly enhanced thrombosis in the K18-hACE2 mice, which was inhibited by simultaneously treating mice with tipiracil, a selective TYMP inhibitor ( Figure ). K18-hACE2/ Tymp -/- mice were resistant to SP-enhanced thrombosis. For the first time, we found that SP, PF4, and TYMP form a complex whose formation is dose-dependently enhanced by TYMP. Conclusions: Our studies suggest that SARS-CoV-2 SP enhances TYMP expression and is prothrombotic and proinflammatory. TYMP inhibition, either via genetic knockout or by its chemical inhibitor, attenuates SP-enhanced thrombosis. TYMP promotes the formation of a PF4/SP complex, which provides a novel insight into COVID-19-associated thrombosis. TYMP could be a novel therapeutic target for COVID-19-associated sequelae.

Investigation of novel bis-thiadiazole bearing schiff base derivatives as effective inhibitors of thymidine phosphorylase: Synthesis, in vitro bioactivity and molecular docking study

Thymidine phosphorylase (TP) is an angiogenic enzyme. It is crucial for the development, invasion and metastasis of tumors as well as angiogenesis. In our current research, we examine how structurally changing bis-thiadiazole bearing bis-schiff bases affects their ability to inhibit TP. Through the oxidative cyclization of pyridine-based bis-thiosemicarbazone with iodine, a series of fourteen analogs of bis-thiadiazole-based bis-imines with pyridine moiety were developed. Newly synthesized scaffolds were assessed in vitro for their thymidine phosphorylase inhibitory potential and showed moderate to good inhibition profile. Eleven scaffolds such as 4a-4d,4f-4 h and 4j-4 m were discovered to be more effective than standard drug at inhibiting the thymidine phosphorylase enzyme with IC50 values of 1.16 ± 1.20, 1.77 ± 1.10, 2.48 ± 1.30, 12.54 ± 1.60, 14.63 ± 1.70, 15.53 ± 1.80, 17.47 ± 1.70, 18.98 ± 1.70, 19.53 ± 1.50, 22.73 ± 2.40 and 24.87 ± 2.80 respectively, while remaining three analogs such as 4n, 4i and 4ewere found to be more potent, but they were less potent than the standard drug. All analogs underwent SAR studies based on the pattern of substitutions around the aryl part of the bis-thiadiazole skeleton. The most active analogs in the synthesized series were then molecular docking study performed to investigate their interactions of active part of enzyme. The results showed that remarkable interactions were exhibited by these analogs with the targeted enzymes active sites. Furthermore, to confirm the structure of synthesized analogs by employing spectroscopic tools such as HREI-MS and NMR.

Hybrid molecules of thiadiazole-based benzothioate and benzenesulfonothioate: synthesis, structural analysis, and evaluation as potential inhibitors of thymidine phosphorylase and β-glucuronidase through in vitro and in silico approaches

The thiadiazole-based benzothioate (3a-f) and benzenesulfonothioate (5a-f) hybrid derivatives were designed and synthesized in a single step reaction. All the synthesized compounds structures were confirmed through spectroscopic techniques including 1H NMR, 13C NMR and HRMS (ESI). Then, the synthesized compounds were subjected to in vitro thymidine phosphorylase and beta-glucuronidase inhibition profile. All the newly synthesized moieties (3a-f) & (5a-f) were found potent and showed moderately to good inhibition profile. Among benzothioate analogues (3a-f), the analogues 3d and 3c were identified to be active inhibitors of thymidine phosphorylase and beta-glucuronidase enzymes having IC50 values of 2.11 ± 0.31 μM & 3.28 ± 0.20 μM (against thymidine phosphorylase) and 2.50 ± 0.20 μM & 3.71 ± 0.10 μM (against beta-glucuronidase) respectively. However, among benzenesulfonothioate (5a-f) analogues, analogues 5a and 5d were found to be significantly active, even more than standard drugs with IC50 values of 2.23 ± 0.13 μM & 3.10 ± 0.17 μM (against thymidine phosphorylase) and 3.12 ± 0.20 μM & 5.60 ± 0.34 μM respectively. The results were compared to standard drugs such as D-saccharic acid with IC50 values of 10.10 ± 0.10 µM (for benzothioate series) & 8.50 ± 0.10 µM (for benzenesulfonothioate series) and 7-Deazaxanthine having IC50 values of 12.20 ± 0.10 µM (for benzothioate series) & 9.20 ± 0.30 µM (benzenesulfonothioate series) respectively. From structure-activity (SAR) analysis, it was confirmed that any variation found in inhibitory activities of both thymidine phosphorylase beta-glucuronidase enzymes was due to different substitution pattern of substituent(s) at variable position of aryl ring. Moreover, a good protein-ligand interaction (PLI) subjected to molecular docking study against shown by the most active analogues against corresponding target with key binding interactions with least binding energies. These findings reveal that thiadiazole-containing benzothioate (3a-f) and benzenesulfonothioate (5a-f) act as thymidine phosphorylase beta-glucuronidase inhibitors to develop novel therapeutics agents for the purpose of drug discovery.

Synthesis, Biological Evaluation and Molecular Docking Studies of Novel Series of Bis-1,2,4-Triazoles as Thymidine Phosphorylase Inhibitor.

Heterocyclic compounds have diverse biological activities and potential in drug development. This study aims to synthesize novel compounds with two 1,2,4-triazole cores and evaluate their biological properties, particularly their inhibitory activity against thymidine phosphorylase (TP), an enzyme involved in various physiological processes. The compounds were synthesized by reacting 5,5'-butane-bis-1,2,4-triazole derivatives with prenyl bromide. Characterization involved various techniques, including spectroscopy and elemental analysis. Antimicrobial potential was evaluated against bacteria and fungi, with comparative antibiotics as references. Inhibitory activity against TP was assessed, and molecular docking studies were conducted. Six compounds were successfully synthesized and their structures confirmed. The synthesized triazole derivatives exhibited high biological activity, with compounds 2 and 6 showing the most promising TP inhibition. Molecular docking studies revealed interactions between compound 2 and TP, involving nine amino acids. The synthesis of novel compounds with two 1,2,4-triazole cores contributes significantly to bis-triazole research. These compounds have potential as anti-tumor agents due to their inhibitory activity against TP, a crucial enzyme in tumor growth and metastasis. Comparative evaluation against antibiotics highlights their potency. Docking results provide insights into their interactions with TP, supporting their potential as potent TP inhibitors. Further research should focus on evaluating their efficacy in biological models, understanding their mechanisms of action, and optimizing their activities. The synthesized compounds with two 1,2,4-triazole cores exhibit significant biological activity, including strong TP inhibition and broad-spectrum antimicrobial effects. These findings emphasize their potential as anti-tumor agents and the need for further exploration and optimization. Future research should focus on evaluating their efficacy in biological models, understanding their mechanisms of action, and developing more potent bis-triazole derivatives for drug discovery efforts. The combined results from assays and docking studies support the therapeutic potential of these compounds as anti-tumor agents.

1,3,4-Oxadiazole: An Emerging Scaffold to Inhibit the Thymidine Phosphorylase as an Anticancer Agent.

Thymidine phosphorylase (TP), also referred to as "platelet-derived endothelial cell growth factor" is crucial to the pyrimidine salvage pathway. TP reversibly transforms thymidine into thymine and 2-deoxy-D-ribose-1-phosphate (dRib-1-P), which further degraded to 2-Deoxy-D-ribose (2DDR), which has both angiogenic and chemotactic activity. In several types of human cancer such as breast and colorectal malignancies, TP is abundantly expressed in response to biological disturbances like hypoxia, acidosis, chemotherapy, and radiation therapy. TP overexpression is highly associated with angiogenic factors such as vascular endothelial growth factor (VEGF), interleukins (ILs), matrix metalloproteases (MMPs), etc., which accelerate tumorigenesis, invasion, metastasis, immune response evasion, and resistant to apoptosis. Hence, TP is recognized as a key target for the development of new anticancer drugs. Heterocycles are the primary structural element of most chemotherapeutics. Even 75% of nitrogen-containing heterocyclic compounds are contributing to the pharmaceutical world. To create the bioactive molecule, medicinal chemists are concentrating on nitrogen-containing heterocyclic compounds such as pyrrole, pyrrolidine, pyridine, imidazole, pyrimidines, pyrazole, indole, quinoline, oxadiazole, benzimidazole, etc. The Oxadiazole motif stands out among all of them due to its enormous significance in medicinal chemistry. The main thrust area of this review is to explore the synthesis, SAR, and the significant role of 1,3,4-oxadiazole derivatives as a TP inhibitor for their chemotherapeutic effects.

Benzothiazole-based 1,3,4-thiadiazole hybrids derivatives as effective inhibitors of urease and thymidine phosphorylase: Synthesis, in vitro and in silico approaches

In the present era, the whole world suffered from varied diseases which are caused by different body enzymes. Among the different thymidine phosphorylase and urease are also produce negative effect on the body. In this regard various organic researchers tried to attempt varied moieties for enzyme inhibition, in the present study we have synthesized benzothiazole based thiadiazole derivatives (1–15) were characterized through 1HNMR, 13CNMR and HREI-MS. Moreover, these compounds were evaluated for biological profiles against thymidine phosphorylase and urease enzymes. Most of the compounds were found with significant potentials but some of them 2(IC50 = 5.70 ± 0.20 µM, 1.80 ± 0.20 µM), 5(IC50 = 4.50 ± 0.50 µM, 1.40 ± 0.10 µM), 6 (IC50 = 4.60 ± 0.20 µM, 2.50 ± 0.60 µM) and 12 (IC50 = 6.30 ± 0.20 µM, 3.10 ± 0.30 µM) exhibits excellent profile against both enzymes while compared with their standard drugs 7-Deazaxanthine, 7DX (IC50 = 13.68 ± 1.20 µM) and Thiourea(IC50 = 3.30 ± 1.30 µM) respectively. Docking studies for the potent compounds were also explored the binding interactions of ligand with active sites of enzymes.

OniLon: Phase II trial of trifluridine/tipiracil (TAS-102) and nanoliposomal irinotecan (nal-IRI) in advanced colorectal cancer.

3580 Background: TAS-102 (FTD/TPI) is a combination of a nucleoside analogue and a thymidine phosphorylase inhibitor, and has showed activity in 5FU-resistant CRC. Nal-IRI achieves higher intra-tumor concentrations than irinotecan (Iri; 142-fold) and its major metabolite, SN-38 (9-fold). This resulted in superior anti-tumor activity compared to free Iri in multiple tumor xenografts. Furthermore, multiple clinical trials have established the activity of nal-IRI in combination with 5FU in pancreaticobiliary cancers. The combination of nal-IRI with the more potent nucleoside analogue TAS-102 may thus result in a more effective systemic therapy. We conducted this study to define the safety and efficacy of the combination of TAS-102 and nal-IRI in advanced CRC. Methods: Eligible patients (pts) on this investigator-initiated phase II study had advanced CRC and must have had disease progression on at least one prior therapy. Additional inclusion criteria - measurable disease, ECOG PS 0-1 & adequate organ function. Based on previously published dose escalation phase I data, the pts were treated at the recommended phase II dose of TAS-102 (given orally at 35mg/m2 bid on days 1-5) and nal-IRI (60mg/m2 IV on day 1) in 14-day cycles. The primary endpoint was objective response rate (ORR) = complete (CR) + partial (PR) response per RECIST v1.1. Multiple secondary endpoints included safety/tolerability, progression-free survival (PFS), overall survival (OS), disease control rate (DCR) and duration of response (DoR). Results: Twenty-two pts were enrolled, of whom 20 were evaluable for response. Male - 50%; ECOG PS 1 – 75%; African Americans – 38%; median age - 58yrs (interquartile range [IQR] 49-67). Median line of prior therapy was 1 (IQR 1-2) and 13.6% (3 pts enrolled during the dose escalation phase) had received prior Iri. 47.6% received concurrent Bevacizumab. ORR was 15% (3 PR, 0 CR). 60% had stable disease (SD) as best response; DCR of 75%. mPFS - 9.7 mos (95% CI: 5.6, 14.2); mOS - 10.1 mos (95% CI: 7.3, 15.9). 12-month PFS and OS rates were 34.6% and 39.5% respectively. At a median follow up of 11.9 mos, DoR was yet to be determined and 50% of the pts had maintained response for 12 mos. Median duration of progression free among pts with SD was 7.6 mos (95% CI: 4.6, 13.2), with a 12-month survival rate of 47.7% (95% CI: 15.5%, 74.5%). Median time to response (TTR) was 4.8mos. Most common treatment related toxicities included fatigue and neutropenia (G3; 27.3% each); anemia and leucopenia (G3; 18.2% each). Other G3 AEs included febrile neutropenia, diarrhea, hypokalemia, lymphopenia and nausea (4.5% each). Conclusions: We demonstrated that the combination of TAS-102 and nal-IRI had an acceptable safety profile, and showed antitumor activity in patients with advanced CRC. Additional biomarker analyses such as survival correlation with UGT1A1 phenotype and RAS mutational status are ongoing. (NCT03368963). Clinical trial information: NCT03368963 .

Phase II study of trifluridine/tipiracil (FTD/TPI) in HER2-negative metastatic breast cancers with or without prior exposure to fluoropyrimidines.

1099 Background: Fluoropyrimidines are commonly used in the treatment of patients (pts) with metastatic breast cancers (MBC). FTD/TPI is an oral drug combination of trifluridine with tipiracil, a thymidine phosphorylase inhibitor preventing rapid degradation of trifluridine, thus allowing for increased exposure to active agent, and has showed activity in pts with colorectal and gastric cancers despite prior exposure to fluoropyrimidines. We investigate the role of FTD/TPI in MBC pts with (Cohort A) or without (Cohort B) prior exposure to fluoropyridines in a single arm phase II study. Methods: Pts were treated with FTD/TPI, and enrolled first into a lead-in dose confirmation phase, followed by two parallel cohorts based on prior exposure to fluoropyrimidines. Primary objectives for each cohort included determination of progression-free survivals (PFS), and secondary objectives included determination of objective response rates (ORR), safety and tolerability. Results: A total of 74 pts were recruited (42 for Cohort A, 32 for Cohort B), of whom 4 belonged to lead-in phase. Dosing was confirmed at FTD/TPI 35mg/m2 days 1-5 and 8-12 of 4-weekly cycles based on lead-in phase with no dose-limiting toxicities observed, and recruitment then proceeded in 2 parallel cohorts. All pts were evaluable for toxicity and survival analyses, and 72 were evaluable for ORR. Median age at enrolment was 62 years (range 32-85), with median of 4 (range 0-14) prior lines therapy in the metastatic setting, and 47% had de novo metastatic disease. Median PFS was 5.7 months (95% CI 3.8 to 8.3) and 9.4 months (95% CI 5.5 to 14.0) respectively in Cohorts A and B. Similar response rates were observed regardless of prior exposure to fluoropyrimidine, with ORR of 19.5% (95% CI 8.8 to 34.9) and 16.1% (95% CI 5.5 to 33.7) in Cohorts A and B, with 6-month clinical benefit rates of 56.1% (95% CI 39.7 to 71.5) and 61.3% (95% CI 42.2 to 78.2) respectively. Safety profile was consistent with known toxicities of FTD/TPI, with most common treatment-related adverse events of neutropenia, fatigue, nausea and anorexia. 64% of pts required dose modifications during study treatment, most commonly due to neutropenia, that could be overcome by dose reduction or prolongation from 4- to 5-weekly cycles. Only 1 pt required discontinuation due to toxicity from therapy. Conclusions: FTD/TPI showed promising anti-tumor activity with meaningful clinical benefit even among pts with prior exposure to fluoropyrimidines, and has a reasonable toxicity profile with appropriate dose modification. An oral chemotherapy option with good disease control provides an attractive treatment alternative to pts with MBC where quality of life is paramount, warranting further investigation in randomised studies. Clinical trial information: NCT04280536 .

Dihydropyrimidone Derivatives as Thymidine Phosphorylase Inhibitors: Inhibition Kinetics, Cytotoxicity, and Molecular Docking.

Overexpression of the thymidine phosphorylase (TP) enzyme induces angiogenesis, which eventually leads to metastasis and tumor growth. The crucial role of TP in cancer development makes it an important target for anticancer drug discovery. Currently, there is only one US-FDA-approved drug, i.e., Lonsurf, a combination of trifluridine and tipiracil, for the treatment of metastatic colorectal cancer. Unfortunately, numerous adverse effects are associated with its use, such as myelosuppression, anemia, and neutropenia. Since the last few decades, the discovery of new, safe, and effective TP inhibitory agents has been rigorously pursued. In the present study, we evaluated a series of previously synthesized dihydropyrimidone derivatives 1-40 for their TP inhibitory potential. Compounds 1, 12, and 33 showed a good activity with IC50 = 314.0 ± 0.90, 303.5 ± 0.40, and 322.6 ± 1.60 µM, respectively. The results of mechanistic studies revealed that compounds 1, 12, and 33 were the non-competitive inhibitors. These compounds were also evaluated for cytotoxicity against 3T3 (mouse fibroblast) cells and were found to be non-cytotoxic. Finally, the molecular docking suggested the plausible mechanism of non-competitive inhibition of TP. The current study thus identifies some dihydropyrimidone derivatives as potential inhibitors of TP, which can be further optimized as leads for cancer treatment.

Abstract 5510: TAS102 synergizes with regorafenib against colorectal and gastric cancer cells

Abstract TAS-102 is an oral formulation consisting of trifluridine (FTD) and thymidine phosphorylase inhibitor tipiracil hydrochloride (TPI). Regorafenib is a multi-targeted tyrosine kinase inhibitor, it inhibits the activities of VEGFR2 and 3, Ret, Kit, PDGFR and Raf kinases and results in the inhibition of tumor angiogenesis and cell proliferation. TAS102 or regorafenib monotherapy can lead to an overall survival benefit in metastatic colorectal cancer (mCRC) patient previously treated with conventional chemotherapy and target therapy (Arnold et al., 2018). TAS102 in combination with bevacizumab, a monoclonal antibody against vascular endothelial growth factor A (VEGF-A), is associated with a significant and clinically relevant improvement in progression-free survival in colorectal cancer (C-TASK FORCE)(Kuboki et al., 2017; Pfeiffer et al., 2020). FTD can synergize with nintedanib to inhibit the growth of colorectal cancer xenografts(Suzuki, Nakagawa, Matsuoka, & Takechi, 2016). We previously reported that regorafenib combined with a fluoropyrimidine can delay disease progression in case reports of multidrug-resistant mCRC patients(Marks et al., 2015). Therefore, we hypothesized that the combination of TAS102 and regorafenib may be active in CRC and other gastrointestinal (GI) cancers, and may in the future provide a treatment option for patients with advanced GI cancer. We investigated the therapeutic effect of TAS102 in combination with regorafenib in preclinical studies employing cell culture, colonosphere assays that enrich for cancer stem cells, and in vivo. We found that TAS102 in combination with regorafenib has synergistic activity against multiple GI cancers in vitro including colorectal and gastric cancer, but not liver cancer cells. TAS102 inhibits colonosphere formation and this effect is potentiated by regorafenib. In vivo anti-tumor effects of TAS102 plus regorafenib appear to be due to anti-proliferative effects, necrosis and angiogenesis inhibition. Growth inhibition by TAS102 plus regorafenib occurs in xenografted tumors regardless of p53, KRAS or BRAF mutations, although more potent tumor suppression was observed with wild-type p53. Regorafenib significantly inhibits TAS102-induced angiogenesis and microvessel density in xenografted tumors, and inhibits TAS102-induced ERK1/2 activation regardless of RAS or BRAF status in vivo. Collectively, TAS102 plus regorafenib is a synergistic drug combination in preclinical models of GI cancer, with regorafenib suppressing TAS102-induced increase in microvessel density and p-ERK as contributing mechanisms. The drug combination may be further tested in gastric and other GI cancers. Citation Format: Jun Zhang, Lanlan Zhou, Shuai Zhao, Wafik S. El-Deiry. TAS102 synergizes with regorafenib against colorectal and gastric cancer cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5510.

Thymidine Phosphorylase Deficiency or Inhibition Preserves Cardiac Function in Mice With Acute Myocardial Infarction.

Background Ischemic cardiovascular disease is the leading cause of death worldwide. Current pharmacologic therapy has multiple limitations, and patients remain symptomatic despite maximal medical therapies. Deficiency or inhibition of thymidine phosphorylase (TYMP) in mice reduces thrombosis, suggesting that TYMP could be a novel therapeutic target for patients with acute myocardial infarction (AMI). Methods and Results A mouse AMI model was established by ligation of the left anterior descending coronary artery in C57BL/6J wild-type and TYMP-deficient (Tymp-/-) mice. Cardiac function was monitored by echocardiography or Langendorff assay. TYMP-deficient hearts had lower baseline contractility. However, cardiac function, systolic left ventricle anterior wall thickness, and diastolic wall strain were significantly greater 4 weeks after AMI compared with wild-type hearts. TYMP deficiency reduced microthrombus formation after AMI. TYMP deficiency did not affect angiogenesis in either normal or infarcted myocardium but increased arteriogenesis post-AMI. TYMP deficiency enhanced the mobilization of bone marrow stem cells and promoted mesenchymal stem cell (MSC) proliferation, migration, and resistance to inflammation and hypoxia. TYMP deficiency increased the number of larger MSCs and decreased matrix metalloproteinase-2 expression, resulting in a high homing capability. TYMP deficiency induced constitutive AKT phosphorylation in MSCs but reduced expression of genes associated with retinoid-interferon-induced mortality-19, a molecule that enhances cell death. Inhibition of TYMP with its selective inhibitor, tipiracil, phenocopied TYMP deficiency, improved post-AMI cardiac function and systolic left ventricle anterior wall thickness, attenuated diastolic stiffness, and reduced infarct size. Conclusions This study demonstrated that TYMP plays an adverse role after AMI. Targeting TYMP may be a novel therapy for patients with AMI.

Depletion of plasma thymidine results in growth retardation and mitochondrial myopathy in mice overexpressing human thymidine phosphorylase

Plasma thymidine levels in rodents are higher than in other mammals including humans, possibly due to a different pattern and lower level of thymidine phosphorylase expression. Here, we generated a novel knock-in (KI) mouse line with high systemic expression of human thymidine phosphorylase to investigate this difference in nucleotide metabolism in rodents. The KI mice showed growth retardation around weaning and died by 4weeks of age with a decrease in plasma thymidine level compared with the litter-control WT mice. These phenotypes were completely or partially rescued by administration of the thymidine phosphorylase inhibitor 5-chloro-6-(2-iminopyrrolidin-1-yl) methyl-2,4(1H,3H)-pyrimidinedione hydrochloride or thymidine, respectively. Interestingly, when thymidine phosphorylase inhibitor administration was discontinued in adult animals, KI mice showed deteriorated grip strength and locomotor activity, decreased bodyweight, and subsequent hind-limb paralysis. Upon histological analyses, we observed axonal degeneration in the spinal cord, muscular atrophy with morphologically abnormal mitochondria in quadriceps, retinal degeneration, and abnormality in the exocrine pancreas. Moreover, we detected mitochondrial DNA depletion in multiple tissues of KI mice. These results indicate that the KI mouse represents a new animal model for mitochondrial diseases and should be applicable for the study of differences in nucleotide metabolism between humans and mice.

QSAR Analysis, Molecular Docking and ADME Studies of Thiobarbituric Acid Derivatives as Thymidine Phosphorylase Inhibitors: A Rational Approach to Anticancer Drug Design by in silico Modelling

Background: Thymidine Phosphorylase (TP) is an imperative target for cancer researchers. In the current research, quantitative structure-activity relationship (QSAR) models were demonstrated to identify new TP inhibitors. Objective: The main objective is to perform a QSAR study on a series of 19 derivatives of thiobarbituric acid and new molecules designed and dock to check potency and efficacy for anticancer activity. Methods: Multiple linear regression analysis (MLR) was used to establish a two-dimensional quantitative structure-activity relationship (2D-QSAR) with regression coefficient values of 0.9781, 0.9513, and 0.9819 for the training set (r2), leave-one-out (LOO) dependent internal regression (q2), and external test set regression (r2 _pred), respectively. Three-dimensional quantitative structure-activity relationship (3DQSAR) model, obtained by using the simulated annealing k nearest neighbour (SA-KNN) method (q2 = 0.7880). Newly designed molecules were subjected to docking studies with 7-deazaxanthine taken as standard. Results: Molecular modelling, structure-based drug design and docking study analysis were performed. The new chemical entities (NCE’s) designed, docked towards targeted receptor and show good results as compared to the standard 7-deazaxanthine. It was found that these molecules bind similar amino acid pocket regions as that of standard. Molecules bind at the active site of TP enzyme involving H bond interactions with shorter distances showed greater affinity. At last, the oral bioavailability and toxic effect were evaluated as absorption, distribution, metabolism, and elimination (ADME) studies by computational means of the Qikprop tool of Schrodinger. Conclusion: One of the most successful and fast-increasing methodologies is molecular modelling. It not only aids in the prediction of specific target compounds but also aids in the cost reduction of valuable substances. QSAR and docking study was performed, and most of the molecules have shown good dock scores. Based on these results, NCE’s for anticancer activity were successfully designed and analysed in this research work which will be helpful for effective drug synthesis with less toxicity in the future. Others: 2D QSAR model was generated by three methods, and the best one was selected for further study. NCEs were planned based on descriptors such as topological, electrostatic, steric, and hydrophobic substitutions around the core.

Phase I study of trifluridine/tipiracil in combination with gemcitabine (gem) and nab-paclitaxel (nab-P) in patients (pts) with advanced pancreatic ductal adenocarcinoma (PDAC).

731 Background: The incidence of PDAC is on the rise and it is predicted to be the 2nd leading cause of cancer related mortality in the next decade. Most patients present with advanced disease at diagnoses with limited systemic treatment options. Fluoropyrimidines are active in PDAC. Lonsurf (L) is an orally administered combination of a thymidine-based nucleic acid analogue, trifluridine, and a thymidine phosphorylase inhibitor, tipiracil hydrochloride. Preclinical data demonstrate Lonsurf may have activity in 5-FU resistant malignancies. This phase I study combines Gem, nab-P, and L. Methods: Gem and nab-P are dosed on days 1 and 15 IV on a 28 day cycle. L (20-30mg/m2) is dosed twice daily on days 2-6 and 16-20 (table 1). Dose escalation is by 3+3 design. Key eligibility include pts with untreated locally advanced or metastatic PDAC, ECOG 0-1, and adequate hepatic and bone marrow function. Results: 14 pts (median age 62 yrs [range 43-74]) have been enrolled. Dose was initiated at DL1. The first 3 pts were treated without DLT. DL2 exceeded the MTD with 1 patient experiencing grade 3 infection (cholangitis). Dose expansion to 7 patients was completed at DL 1 with no further DLTs. The RP2D is Gem 800mg/m2, Nab-P 100mg/m2, and L 25mg/m2. Of the 10 patients with evaluable disease, 2 (20%) had PR and 7 (70%) had SD. Pts were on study a median of 14 months (range 4 -31+). Most common grade 3/4 AEs include fatigue (46%,) neutropenia (38%), anemia (31%) anorexia (15%), nausea (15%), vomiting (15%), abdominal pain (15%), hyperglycemia (15%). No grade 5 events occurred. Conclusions: The RP2D is Gem 800mg/m2, Nab-P 100mg/m2, and L 25mg/m2. This combination was well tolerated with expected toxicities of myelosuppression with prolonged responses seen. Clinical trial information: NCT04046887 . [Table: see text]

A Rational Approach to Anticancer Drug Design: 2D and 3D- QSAR, Molecular Docking and Prediction of ADME Properties using Silico Studies of Thymidine Phosphorylase Inhibitors

Background: Cancer is the most prevalent disease seen nowadays. Thymidine phosphorylase (TP) is an angiogenic enzyme that is overexpressed in many solid tumors. Over the years, Thymidine phosphorylase has emerged as a novel target for anticancer drug development as an inhibitor. Objective: To design novel oxadiazole-isatin pharmacophore-containing molecules and explore their structural requirements related to the anticancer activity. Methods: Pharmacophore optimisation was carried out for oxadiazole-isatin hybrid molecules using molecular modeling studies (2D and 3D QSAR). Further, the new chemical entities were designed using the combilib tool of V life software. To have a better understanding of the binding interactions, the newly designed molecules were docked. To achieve a drug-like pharmacokinetic profile, molecules were also tested for ADME prediction. Results: Two-Dimensional Quantitative Structure-Activity Relationship (2D-QSAR) model was generated using the multiple regression method with r2 = 0.84 and q2 = 0.76. Three-Dimensional Quantitative Structure-Activity Relationship (3D-QSAR) model was obtained by simulated annealing k nearest near (SA kNN) method with q2 = 0.8099. Molecular docking studies showed promising results. Compound 5 was found to be with the best dock score and the best fit to the active site pocket of the thymidylate phosphorylase enzyme. The compounds have notable absorption, distribution, metabolism, and excretion (ADME) properties that can be predicted to assure a drug-like pharmacokinetic profile. Conclusion: One of the most successful and fast-increasing methodologies is molecular modeling. It not only aids in the prediction of specific target compounds but also aids in the cost reduction of valuable substances. The successful use of molecular modeling was done in this study, with caution taken to avoid any chance co-relation. Optimised pharmacophore was obtained and new chemical entities were designed. Docking studies revealed that Compound 5 has shown better H-bond interaction with Lys 221 and Thr 151 with bond distances 2.0 Α° and 1.8 Α° which is the most active molecule. ADME tests discovered that the majority of the newly designed compounds were within a reasonable range as required in a druglike pharmacokinetic profile. Molecules 2, 4, 5, 6 can be considered as a lead for future synthesis and biological screening.

Capecitabine induces hand-foot syndrome through elevated thymidine phosphorylase-mediated locoregional toxicity and GSDME-driven pyroptosis that can be relieved by tipiracil.

Hand-foot syndrome (HFS) is a serious dose-limiting cutaneous toxicity of capecitabine-containing chemotherapy, leading to a deteriorated quality of life and negative impacts on chemotherapy treatment. The symptoms of HFS have been widely reported, but the precise molecular and cellular mechanisms remain unknown. The metabolic enzyme of capecitabine, thymidine phosphorylase (TP) may be related to HFS. Here, we investigated whether TP contributes to the HFS and the molecular basis of cellular toxicity of capecitabine. TP-/- mice were generated to assess the relevance of TP and HFS. Cellular toxicity and signalling mechanisms were assessed by in vitro and in vivo experiments. TP-/- significantly reduced capecitabine-induced HFS, indicating that the activity of TP plays a critical role in the development of HFS. Further investigations into the cellular mechanisms revealed that the cytotoxicity of the active metabolite of capecitabine, 5-DFUR, was attributed to the cleavage of GSDME-mediated pyroptosis. Finally, we demonstrated that capecitabine-induced HFS could be reversed by local application of the TP inhibitor tipiracil. Our findings reveal that the presence of elevated TP expression in the palm and sole aggravates local cell cytotoxicity, further explaining the molecular basis underlying 5-DFUR-induced cellular toxicity and providing a promising approach to the therapeutic management of HFS.

The mechanism underlying resistance to 5-fluorouracil and its reversal by the inhibition of thymidine phosphorylase in breast cancer cells.

Fluoro-deoxyuridine monophosphate (FdUMP) is an active metabolite of 5-fluorouracil (5-FU) synthesized through two hypothesized pathways: The orotate phosphoribosyl transferase-ribonucleotide reductase (OPRT-RR) pathway and the thymidine phosphorylase-thymidine kinase (TP-TK) pathway. In the present study, the mechanism underlying 5-FU resistance was investigated, focusing on changes in 5-FU metabolism using MCF-7, 5-FU-resistant MCF-7/5-FUR, MDA-MB-231 and 5-FU-resistant MDA-MB-231/5-FUR breast cancer cells. The amount of FdUMP present following treatment with 5-FU was determined by the density of the upper band of thymidylate synthase detected by western blotting, and its changes were investigated. MCF-7/5-FUR cells exhibited 5-FU resistance (36.6-fold), and showed decreased OPRT (-69.3%) and TK (-42.6%) levels. MDA-MB-231/5-FUR cells also exhibited 5-FU resistance (15.8-fold), and showed decreased TP (-79.0%) and increased TK (+184%) levels. MCF-7/5-FUR and MDA-MB-231/5-FUR cells both showed decreased synthesis of FdUMP by 91 and 86%, respectively. In MCF-7 and MCF-7/5-FUR cells, the synthesis of FdUMP was decreased when 5-FU was combined with an RR inhibitor, indicating that FdUMP was synthesized through the OPRT-RR pathway. The synthesis of FdUMP was decreased when 5-FU was combined with a TP inhibitor in MDA-MB-231 cells and combined with an RR inhibitor in MDA-MB-231/5-FUR cells, indicating that the synthesis pathway of FdUMP was changed from the TP-TK pathway to the OPRT-RR pathway on acquiring resistance to 5-FU. Notably, the synthesis of FdUMP was increased and the resistance to 5-FU was reversed in MCF-7/5-FUR cells (half maximal inhibitory concentration (IC50): 219.9 to 0.093 µM) and MDA-MB-231/5-FUR cells (IC50: 157.3 to 31.0 µM) when 5-FU was combined with a TP inhibitor. In conclusion, the metabolism of 5-FU and the mechanism underlying the resistance to 5-FU differed among cell lines, and inhibition of TP reversed resistance to 5-FU, thus suggesting that the combination of 5-FU and a TP inhibitor may be considered a promising cancer therapy.

P-50 RETRO-TAS, a retrospective observational study of rifluridine/tipiracil in chemorefractory metastatic colorectal cancer

Trifluridine/tipiracil (TAS-102) is an oral combination of an antineoplastic thymidine-based nucleoside analogue, trifluridine, and the thymidine phosphorylase (TPase) inhibitor, tipiracil hydrochloride, indicated for patients (pts) with metastatic colorectal cancer (mCRC) as third line therapy. The approved dose of TAS-102 in adults is 35 mg/m2/dose administered orally twice daily on Days 1 to 5 and Days 8 to 12 of each 28-day cycle as long as benefit is observed or until unacceptable toxicity occurs.

Study protocol of an open-label, single-arm, phase II trial investigating the efficacy and safety of trifluridine/tipiracil combined with irinotecan as a second-line therapy in patients with cholangiocarcinoma (TRITICC).

TPS4176 Background: Biliary tract cancers (BTC) currently account for ̃15% of all primary liver cancers and ̃3% of gastrointestinal malignancies. Gemcitabine/Cisplatin has been the standard of care in the first-line therapy of BTC for a decade. Despite recently some survival benefit has been shown in adding a checkpoint inhibitor, further lines of treatment are only poorly defined. In the ABC-06 phase-3 study, second-line FOLFOX demonstrated a moderate but significant improvement of survival and might be regarded as a standard of care. The combination of liposomal Irinotecan and 5-FU infusion pump also improved survival after first line therapy. Both mentioned second-line regimens are based on limited evidence and questionable generalizability. Thus, there is a high need for novel treatment concepts in patients without targetable genetic alterations. Trifluridine/tipiracil (FTD/TPI) is a orally active, antimetabolite agent comprised of trifluridine, a thymidine-based nucleoside analogue, and tipiracil, a potent thymidine phosphorylase inhibitor. Recent reports provided evidence of an antitumor activity of FTD/TPI plus Irinotecan as well in patients with BTC. Therefore, the TRITICC trial was designed to evaluate the safety and efficacy of FTD/TPI plus irinotecan in patients with BTC refractory to previous Gemcitabine based treatment. Methods: TRITICC (NCT04059562) is an interventional, prospective, open-label, non-randomized, exploratory, multicenter, single-arm phase IIA clinical trial that evaluates the safety and efficacy of FTD/TPI (25 mg/m² body surface area (BSA), BID, orally on days 1-5 followed by a 9-days recovery period from day 6 trough day 14 of each 14-days treatment cycle) plus irinotecan (on day 1 of each cycle at a dose of 180 mg/m2) in adult patients with histologically verified locally advanced or metastatic BTC (including cholangiocarcinoma and gallbladder or ampullary carcinoma) with documented radiological disease progression to first-line gemcitabine based chemotherapy. A total of 28 patients is planned to be enrolled in 6 sites across Germany. Study treatment will be continued until disease progression according to RECIST 1.1 criteria or occurrence of unacceptable toxicity. The effect of FTD/TPI plus irinotecan on progression-free survival will be analyzed as primary endpoint. Safety (according to NCI-CTCAE), response rates and overall survival are secondary endpoints. In addition, a comprehensive translational research program is part of the study and might provide findings about predictive markers with regard to response, survival periods and resistance to treatment. Currently, 3 out of the planned 6 German study sites are opened for recruitment and 6 patients have been enrolled. The primary study endpoint is estimated to be evaluated in 2023. Clinical trial information: NCT04059562.