RESUMEN
A combination of focused library and virtual screening, hit expansion, and rational design has resulted in the development of a series of inhibitors of RETV804M kinase, the anticipated drug-resistant mutant of RET kinase. These agents do not inhibit the wild type (wt) isoforms of RET or KDR and therefore offer a potential adjunct to RET inhibitors currently undergoing clinical evaluation.
RESUMEN
Patients with metastatic pancreatic ductal adenocarcinoma (PDAC) have an average survival of less than 1 year, underscoring the importance of evaluating novel targets with matched targeted agents. We recently identified that poly (ADP) ribose glycohydrolase (PARG) is a strong candidate target due to its dependence on the pro-oncogenic mRNA stability factor HuR (ELAVL1). Here, we evaluated PARG as a target in PDAC models using both genetic silencing of PARG and established small-molecule PARG inhibitors (PARGi), PDDX-01/04. Homologous repair-deficient cells compared with homologous repair-proficient cells were more sensitive to PARGi in vitro. In vivo, silencing of PARG significantly decreased tumor growth. PARGi synergized with DNA-damaging agents (i.e., oxaliplatin and 5-fluorouracil), but not with PARPi therapy. Mechanistically, combined PARGi and oxaliplatin treatment led to persistence of detrimental PARylation, increased expression of cleaved caspase-3, and increased γH2AX foci. In summary, these data validate PARG as a relevant target in PDAC and establish current therapies that synergize with PARGi. SIGNIFICANCE: PARG is a potential target in pancreatic cancer as a single-agent anticancer therapy or in combination with current standard of care.
Asunto(s)
Carcinoma Ductal Pancreático/tratamiento farmacológico , Glicósido Hidrolasas/antagonistas & inhibidores , Neoplasias Pancreáticas/tratamiento farmacológico , Animales , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patología , Línea Celular Tumoral , Daño del ADN , Inhibidores Enzimáticos/farmacología , Femenino , Silenciador del Gen , Glicósido Hidrolasas/genética , Humanos , Ratones Desnudos , Terapia Molecular Dirigida , Oxaliplatino/farmacología , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patología , Reparación del ADN por Recombinación , Bibliotecas de Moléculas Pequeñas/farmacología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Inhibitors of poly(ADP-ribose) polymerase (PARP) have demonstrated efficacy in women with BRCA-mutant ovarian cancer. However, only 15%-20% of ovarian cancers harbor BRCA mutations, therefore additional therapies are required. Here, we show that a subset of ovarian cancer cell lines and ex vivo models derived from patient biopsies are sensitive to a poly(ADP-ribose) glycohydrolase (PARG) inhibitor. Sensitivity is due to underlying DNA replication vulnerabilities that cause persistent fork stalling and replication catastrophe. PARG inhibition is synthetic lethal with inhibition of DNA replication factors, allowing additional models to be sensitized by CHK1 inhibitors. Because PARG and PARP inhibitor sensitivity are mutually exclusive, our observations demonstrate that PARG inhibitors have therapeutic potential to complement PARP inhibitor strategies in the treatment of ovarian cancer.
Asunto(s)
Replicación del ADN/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Neoplasias Ováricas/genética , Línea Celular Tumoral , Quinasa 1 Reguladora del Ciclo Celular (Checkpoint 1) , Femenino , Glicósido Hidrolasas/antagonistas & inhibidores , Humanos , Neoplasias Ováricas/tratamiento farmacológico , Neoplasias Ováricas/enzimología , Inhibidores de Poli(ADP-Ribosa) Polimerasas/farmacología , Quinazolinonas/farmacologíaRESUMEN
Fluorination of metabolic hotspots in a molecule is a common medicinal chemistry strategy to improve in vivo half-life and exposure and, generally, this strategy offers significant benefits. Here, we report the application of this strategy to a series of poly-ADP ribose glycohydrolase (PARG) inhibitors, resulting in unexpected in vivo toxicity which was attributed to this single-atom modification.
Asunto(s)
Ciclopropanos/farmacología , Glicósido Hidrolasas/toxicidad , Microsomas Hepáticos/efectos de los fármacos , Administración Oral , Animales , Ciclopropanos/administración & dosificación , Ciclopropanos/química , Ciclopropanos/farmacocinética , Glicósido Hidrolasas/administración & dosificación , Glicósido Hidrolasas/química , Glicósido Hidrolasas/farmacocinética , Semivida , Humanos , Ratones , Microsomas Hepáticos/metabolismoRESUMEN
DNA damage repair enzymes are promising targets in the development of new therapeutic agents for a wide range of cancers and potentially other diseases. The enzyme poly(ADP-ribose) glycohydrolase (PARG) plays a pivotal role in the regulation of DNA repair mechanisms; however, the lack of potent drug-like inhibitors for use in cellular and in vivo models has limited the investigation of its potential as a novel therapeutic target. Using the crystal structure of human PARG in complex with the weakly active and cytotoxic anthraquinone 8a, novel quinazolinedione sulfonamides PARG inhibitors have been identified by means of structure-based virtual screening and library design. 1-Oxetan-3-ylmethyl derivatives 33d and 35d were selected for preliminary investigations in vivo. X-ray crystal structures help rationalize the observed structure-activity relationships of these novel inhibitors.
Asunto(s)
Reparación del ADN , Diseño de Fármacos , Inhibidores de Glicósido Hidrolasas/química , Inhibidores de Glicósido Hidrolasas/farmacología , Glicósido Hidrolasas/antagonistas & inhibidores , Quinazolinonas/química , Quinazolinonas/farmacología , Administración Oral , Animales , Disponibilidad Biológica , Dominio Catalítico , Inhibidores de Glicósido Hidrolasas/administración & dosificación , Inhibidores de Glicósido Hidrolasas/farmacocinética , Glicósido Hidrolasas/química , Glicósido Hidrolasas/metabolismo , Células HeLa , Humanos , Masculino , Ratones , Modelos Moleculares , Quinazolinonas/administración & dosificación , Quinazolinonas/farmacocinética , Relación Estructura-ActividadRESUMEN
Pharmacologic inhibition of LSD1 promotes blast cell differentiation in acute myeloid leukemia (AML) with MLL translocations. The assumption has been that differentiation is induced through blockade of LSD1's histone demethylase activity. However, we observed that rapid, extensive, drug-induced changes in transcription occurred without genome-wide accumulation of the histone modifications targeted for demethylation by LSD1 at sites of LSD1 binding and that a demethylase-defective mutant rescued LSD1 knockdown AML cells as efficiently as wild-type protein. Rather, LSD1 inhibitors disrupt the interaction of LSD1 and RCOR1 with the SNAG-domain transcription repressor GFI1, which is bound to a discrete set of enhancers located close to transcription factor genes that regulate myeloid differentiation. Physical separation of LSD1/RCOR1 from GFI1 is required for drug-induced differentiation. The consequent inactivation of GFI1 leads to increased enhancer histone acetylation within hours, which directly correlates with the upregulation of nearby subordinate genes.
Asunto(s)
Proteínas de Unión al ADN/antagonistas & inhibidores , Histona Demetilasas/antagonistas & inhibidores , Leucemia Mieloide Aguda/tratamiento farmacológico , Factores de Transcripción/antagonistas & inhibidores , Diferenciación Celular/efectos de los fármacos , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Histona Demetilasas/genética , Histona Demetilasas/metabolismo , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patología , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Artificial intelligence in drug design in experiencing a wave of excitement not seen since the emergence of computational chemistry in the late 1980s and early 1990s. Apparently failing to learn the lessons of recent history, we are promised imminent and pervasive solutions to the ills of drug design and significant increases in productivity as we seek to deliver innovative new therapeutics. However, do significant issues remain to be answered before AI enters the day-to-day toolbox of the practicing medicinal chemist?
RESUMEN
Inhibition of lysine specific demethylase 1 (LSD1) has been shown to induce the differentiation of leukemia stem cells in acute myeloid leukemia (AML). Irreversible inhibitors developed from the nonspecific inhibitor tranylcypromine have entered clinical trials; however, the development of effective reversible inhibitors has proved more challenging. Herein, we describe our efforts to identify reversible inhibitors of LSD1 from a high throughput screen and subsequent in silico modeling approaches. From a single hit (12) validated by biochemical and biophysical assays, we describe our efforts to develop acyclic scaffold-hops from GSK-690 (1). A further scaffold modification to a (4-cyanophenyl)glycinamide (e.g., 29a) led to the development of compound 32, with a Kd value of 32 nM and an EC50 value of 0.67 µM in a surrogate cellular biomarker assay. Moreover, this derivative does not display the same level of hERG liability as observed with 1 and represents a promising lead for further development.
Asunto(s)
Antineoplásicos/síntesis química , Antineoplásicos/farmacología , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/farmacología , Glicina/análogos & derivados , Histona Demetilasas/antagonistas & inhibidores , Leucemia/tratamiento farmacológico , Compuestos de Espiro/farmacología , Biomarcadores , Línea Celular Tumoral , Simulación por Computador , Diseño de Fármacos , Descubrimiento de Drogas , Canales de Potasio Éter-A-Go-Go/efectos de los fármacos , Glicina/síntesis química , Glicina/farmacología , Ensayos Analíticos de Alto Rendimiento , Humanos , Modelos Moleculares , Simulación del Acoplamiento Molecular , Compuestos de Espiro/síntesis química , Relación Estructura-Actividad , Tranilcipromina/análogos & derivados , Tranilcipromina/química , Tranilcipromina/farmacologíaRESUMEN
As part of our ongoing efforts to develop reversible inhibitors of LSD1, we identified a series of 4-(pyrrolidin-3-yl)benzonitrile derivatives that act as successful scaffold-hops of the literature inhibitor GSK-690. The most active compound, 21g, demonstrated a Kd value of 22nM and a biochemical IC50 of 57nM. In addition, this compound displayed improved selectivity over the hERG ion channel compared to GSK-690, and no activity against the related enzymes MAO-A and B. In human THP-1 acute myeloid leukaemia cells, 21g was found to increase the expression of the surrogate cellular biomarker CD86. This work further demonstrates the versatility of scaffold-hopping asa method to develop structurally diverse, potent inhibitors of LSD1.
Asunto(s)
Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Histona Demetilasas/antagonistas & inhibidores , Nitrilos/química , Nitrilos/farmacología , Sitios de Unión , Línea Celular Tumoral , Diseño de Fármacos , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/síntesis química , Histona Demetilasas/metabolismo , Humanos , Concentración 50 Inhibidora , Simulación del Acoplamiento Molecular , Nitrilos/síntesis química , Estructura Terciaria de Proteína , Pirrolidinas/química , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
A series of reversible inhibitors of lysine specific demethylase 1 (LSD1) with a 5-hydroxypyrazole scaffold have been developed from compound 7, which was identified from the patent literature. Surface plasmon resonance (SPR) and biochemical analysis showed it to be a reversible LSD1 inhibitor with an IC50 value of 0.23µM. Optimisation of this compound by rational design afforded compounds with Kd values of <10nM. In human THP-1 cells, these compounds were found to upregulate the expression of the surrogate cellular biomarker CD86. Compound 11p was found to have moderate oral bioavailability in mice suggesting its potential for use as an in vivo tool compound.
Asunto(s)
Histona Demetilasas/antagonistas & inhibidores , Pirazoles/química , Animales , Antígeno B7-2/metabolismo , Sitios de Unión , Dominio Catalítico , Diferenciación Celular/efectos de los fármacos , Línea Celular , Semivida , Histona Demetilasas/metabolismo , Humanos , Concentración 50 Inhibidora , Ratones , Simulación del Acoplamiento Molecular , Pirazoles/síntesis química , Pirazoles/farmacocinética , Pirazoles/farmacología , Relación Estructura-Actividad , Resonancia por Plasmón de SuperficieRESUMEN
As scientists, we are comfortable communicating our work to our peers. However, communicating with equal passion to those outside our field is something we as a community often shy away from. This reticence has often been exploited by those wishing to present their own view of the science we practice. Herein, we urge the scientific community to actively re-engage with the general public, openly and creatively sharing our endeavors beyond these pages, in order to reconnect with the real consumers of the work we produce.
RESUMEN
The enzyme poly(ADP-ribose) glycohydrolase (PARG) performs a critical role in the repair of DNA single strand breaks (SSBs). However, a detailed understanding of its mechanism of action has been hampered by a lack of credible, cell-active chemical probes. Herein, we demonstrate inhibition of PARG with a small molecule, leading to poly(ADP-ribose) (PAR) chain persistence in intact cells. Moreover, we describe two advanced, and chemically distinct, cell-active tool compounds with convincing on-target pharmacology and selectivity. Using one of these tool compounds, we demonstrate pharmacology consistent with PARG inhibition. Further, while the roles of PARG and poly(ADP-ribose) polymerase (PARP) are closely intertwined, we demonstrate that the pharmacology of a PARG inhibitor differs from that observed with the more thoroughly studied PARP inhibitor olaparib. We believe that these tools will facilitate a wider understanding of this important component of DNA repair and may enable the development of novel therapeutic agents exploiting the critical dependence of tumors on the DNA damage response (DDR).
Asunto(s)
Reparación del ADN , Glicósido Hidrolasas/química , Sondas Moleculares/química , Ftalazinas/farmacología , Piperazinas/farmacología , Inhibidores Enzimáticos/farmacología , Glicósido Hidrolasas/antagonistas & inhibidores , Células HeLa , Humanos , Resonancia por Plasmón de SuperficieRESUMEN
We have previously reported a series of anilinoquinazoline derivatives as potent and selective biochemical inhibitors of the RET kinase domain. However, these derivatives displayed diminished cellular potency. Herein we describe further optimisation of the series through modification of their physicochemical properties, delivering improvements in cell potency. However, whilst cellular selectivity against key targets could be maintained, combining cell potency and acceptable pharmacokinetics proved challenging.
Asunto(s)
Compuestos de Anilina/farmacología , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas c-ret/antagonistas & inhibidores , Quinazolinas/farmacología , Compuestos de Anilina/síntesis química , Compuestos de Anilina/química , Relación Dosis-Respuesta a Droga , Humanos , Modelos Moleculares , Estructura Molecular , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/química , Proteínas Proto-Oncogénicas c-ret/metabolismo , Quinazolinas/síntesis química , Quinazolinas/química , Relación Estructura-ActividadRESUMEN
Tyrosyl-DNA phosphodiesterase 2 (TDP2) is a 5'-tyrosyl DNA phosphodiesterase important for the repair of DNA adducts generated by non-productive (abortive) activity of topoisomerase II (TOP2). TDP2 facilitates therapeutic resistance to topoisomerase poisons, which are widely used in the treatment of a range of cancer types. Consequently, TDP2 is an interesting target for the development of small molecule inhibitors that could restore sensitivity to topoisomerase-directed therapies. Previous studies identified a class of deazaflavin-based molecules that showed inhibitory activity against TDP2 at therapeutically useful concentrations, but their mode of action was uncertain. We have confirmed that the deazaflavin series inhibits TDP2 enzyme activity in a fluorescence-based assay, suitable for high-throughput screen (HTS)-screening. We have gone on to determine crystal structures of these compounds bound to a 'humanized' form of murine TDP2. The structures reveal their novel mode of action as competitive ligands for the binding site of an incoming DNA substrate, and point the way to generating novel and potent inhibitors of TDP2.
Asunto(s)
Hidrolasas Diéster Fosfóricas/metabolismo , Riboflavina/química , Animales , Sitios de Unión , Cristalografía por Rayos X , Activación Enzimática/efectos de los fármacos , Humanos , Ratones , Hidrolasas Diéster Fosfóricas/química , Unión Proteica , Desnaturalización Proteica , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Riboflavina/análogos & derivados , Riboflavina/farmacología , TemperaturaRESUMEN
Deregulation of the receptor tyrosine kinase RET has been implicated in medullary thyroid cancer, a small percentage of lung adenocarcinomas, endocrine-resistant breast cancer and pancreatic cancer. There are several clinically approved multi-kinase inhibitors that target RET as a secondary pharmacology but additional activities, most notably inhibition of KDR, lead to dose-limiting toxicities. There is, therefore, a clinical need for more specific RET kinase inhibitors. Herein we report our efforts towards identifying a potent and selective RET inhibitor using vandetanib 1 as the starting point for structure-based drug design. Phenolic anilinoquinazolines exemplified by 6 showed improved affinities towards RET but, unsurprisingly, suffered from high metabolic clearance. Efforts to mitigate the metabolic liability of the phenol led to the discovery that a flanking substituent not only improved the hepatocyte stability, but could also impart a significant gain in selectivity. This culminated in the identification of 36; a potent RET inhibitor with much improved selectivity against KDR.
Asunto(s)
Piperidinas/química , Piperidinas/farmacología , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas c-ret/antagonistas & inhibidores , Quinazolinas/química , Quinazolinas/farmacología , Animales , Línea Celular , Diseño de Fármacos , Humanos , Ratones , Simulación del Acoplamiento Molecular , Piperidinas/farmacocinética , Inhibidores de Proteínas Quinasas/farmacocinética , Proteínas Proto-Oncogénicas c-ret/metabolismo , Quinazolinas/farmacocinéticaRESUMEN
Chronic inflammation is a hallmark of many cancers, yet the pathogenic mechanisms that distinguish cancer-associated inflammation from benign persistent inflammation are still mainly unclear. Here, we report that the protein kinase ERK5 controls the expression of a specific subset of inflammatory mediators in the mouse epidermis, which triggers the recruitment of inflammatory cells needed to support skin carcinogenesis. Accordingly, inactivation of ERK5 in keratinocytes prevents inflammation-driven tumorigenesis in this model. In addition, we found that anti-ERK5 therapy cooperates synergistically with existing antimitotic regimens, enabling efficacy of subtherapeutic doses. Collectively, our findings identified ERK5 as a mediator of cancer-associated inflammation in the setting of epidermal carcinogenesis. Considering that ERK5 is expressed in almost all tumor types, our findings suggest that targeting tumor-associated inflammation via anti-ERK5 therapy may have broad implications for the treatment of human tumors.
Asunto(s)
Carcinogénesis/genética , Inflamación/genética , Proteína Quinasa 7 Activada por Mitógenos/biosíntesis , Neoplasias Cutáneas/genética , Animales , Carcinógenos/toxicidad , Epidermis/metabolismo , Epidermis/patología , Regulación Neoplásica de la Expresión Génica , Humanos , Inflamación/inducido químicamente , Inflamación/complicaciones , Inflamación/patología , Queratinocitos/metabolismo , Queratinocitos/patología , Ratones , Ratones Transgénicos , Proteína Quinasa 7 Activada por Mitógenos/genética , Neoplasias Cutáneas/inducido químicamente , Neoplasias Cutáneas/etiología , Neoplasias Cutáneas/patologíaRESUMEN
The contraction in research within pharma has seen a renaissance in drug discovery within the academic setting. Often, groups grow organically from academic research laboratories, exploiting a particular area of novel biology or new technology. However, increasingly, new groups driven by industrial staff are emerging with demonstrable expertise in the delivery of medicines. As part of a strategic review by Cancer Research UK (CR-UK), the drug discovery team at the Manchester Institute was established to translate novel research from the Manchester cancer research community into drug discovery programmes. From a standing start, we have taken innovative approaches to solve key issues faced by similar groups, such as hit finding and target identification. Herein, we share our lessons learnt and successful strategies.
Asunto(s)
Academias e Institutos , Antineoplásicos/uso terapéutico , Descubrimiento de Drogas/métodos , Neoplasias/tratamiento farmacológico , Investigación Biomédica Traslacional/métodos , Academias e Institutos/organización & administración , Antineoplásicos/química , Conducta Cooperativa , Descubrimiento de Drogas/organización & administración , Inglaterra , Humanos , Modelos Organizacionales , Terapia Molecular Dirigida , Neoplasias/metabolismo , Neoplasias/patología , Desarrollo de Programa , Investigadores/organización & administración , Transducción de Señal/efectos de los fármacos , Factores de Tiempo , Investigación Biomédica Traslacional/organización & administración , Flujo de TrabajoRESUMEN
In the 10 years since the discovery of lysine-specific demethylase 1 (LSD1), this epigenetic eraser has emerged as an important target of interest in oncology. More specifically, research has demonstrated that it plays an essential role in the self-renewal of leukemic stem cells in acute myeloid leukemia (AML). This review will cover clinical aspects of AML, the role of epigenetics in the disease, and discuss the research that led to the first irreversible inhibitors of LSD1 entering clinical trials for the treatment of AML in 2014. We also review recent achievements and progress in the development of potent and selective reversible inhibitors of LSD1. These compounds differ in their mode of action from tranylcypromine derivatives and could facilitate novel biochemical studies to probe the pathways mediated by LSD1. In this review, we will critically evaluate the strengths and weaknesses of published series of reversible LSD1 inhibitors. Overall, while the development of reversible inhibitors to date has been less fruitful than that of irreversible inhibitors, there is still the possibility for their use to facilitate further research into the roles and functions of LSD1 and to expand the therapeutic applications of LSD1 inhibitors in the clinic.
Asunto(s)
Histona Demetilasas/química , Leucemia Mieloide Aguda/tratamiento farmacológico , Lisina/química , Animales , Antineoplásicos/química , Diseño de Fármacos , Ensayos de Selección de Medicamentos Antitumorales , Epigénesis Genética , Regulación Leucémica de la Expresión Génica , Humanos , Concentración 50 Inhibidora , Ratones , Poliaminas/química , Resultado del TratamientoRESUMEN
The target of rapamycin (TOR) kinase regulates cell growth and division. Rapamycin only inhibits a subset of TOR activities. Here we show that in contrast to the mild impact of rapamycin on cell division, blocking the catalytic site of TOR with the Torin1 inhibitor completely arrests growth without cell death in Schizosaccharomyces pombe. A mutation of the Tor2 glycine residue (G2040D) that lies adjacent to the key Torin-interacting tryptophan provides Torin1 resistance, confirming the specificity of Torin1 for TOR. Using this mutation, we show that Torin1 advanced mitotic onset before inducing growth arrest. In contrast to TOR inhibition with rapamycin, regulation by either Wee1 or Cdc25 was sufficient for this Torin1-induced advanced mitosis. Torin1 promoted a Polo and Cdr2 kinase-controlled drop in Wee1 levels. Experiments in human cell lines recapitulated these yeast observations: mammalian TOR (mTOR) was inhibited by Torin1, Wee1 levels declined and mitotic commitment was advanced in HeLa cells. Thus, the regulation of the mitotic inhibitor Wee1 by TOR signalling is a conserved mechanism that helps to couple cell cycle and growth controls.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Mitosis/efectos de los fármacos , Naftiridinas/farmacología , Proteínas Nucleares/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Schizosaccharomyces/crecimiento & desarrollo , Secuencia de Aminoácidos , Dominio Catalítico , Muerte Celular , Resistencia a Medicamentos , Puntos de Control de la Fase G1 del Ciclo Celular , Células HeLa , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina , Diana Mecanicista del Complejo 2 de la Rapamicina , Datos de Secuencia Molecular , Complejos Multiproteicos/antagonistas & inhibidores , Complejos Multiproteicos/metabolismo , Mutagénesis Sitio-Dirigida , Fosfatidilinositol 3-Quinasas/metabolismo , Transporte de Proteínas , Schizosaccharomyces/efectos de los fármacos , Schizosaccharomyces/enzimología , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Serina-Treonina Quinasas TOR/metabolismoRESUMEN
The recently discovered enzyme tyrosyl-DNA phosphodiesterase 2 (TDP2) has been implicated in the topoisomerase-mediated repair of DNA damage. In the clinical setting, it has been hypothesized that TDP2 may mediate drug resistance to topoisomerase II (topo II) inhibition by etoposide. Therefore, selective pharmacological inhibition of TDP2 is proposed as a novel approach to overcome intrinsic or acquired resistance to topo II-targeted drug therapy. Following a high-throughput screening (HTS) campaign, toxoflavins and deazaflavins were identified as the first reported sub-micromolar and selective inhibitors of this enzyme. Toxoflavin derivatives appeared to exhibit a clear structure-activity relationship (SAR) for TDP2 enzymatic inhibition. However, we observed a key redox liability of this series, and this, alongside early in vitro drug metabolism and pharmacokinetics (DMPK) issues, precluded further exploration. The deazaflavins were developed from a singleton HTS hit. This series showed distinct SAR and did not display redox activity; however low cell permeability proved to be a challenge.