Microglia and glioblastoma heterocellular interplay sustains tumour growth and proliferation as an off-target effect of radiotherapy.

Glioblastoma (GBM), a WHO grade IV glioma, is a malignant primary brain tumour for which combination of surgery, chemotherapy and radiotherapy is the first-line approach despite adverse effects. Tumour microenvironment (TME) is characterized by an interplay of cells and soluble factors holding a critical role in neoplastic development. Significant pathophysiological changes have been found in GBM TME, such as glia activation and oxidative stress. Microglia play a crucial role in favouring GBM growth, representing target cells of immune escape mechanisms. Our study aims at analysing radiation-induced effects in modulating intercellular communication and identifying the basis of protective mechanisms in radiation-naïve GBM cells. Tumour cells were treated with conditioned media (CM) derived from 0, 2 or 15 Gy irradiated GBM cells or 0, 2 or 15 Gy irradiated human microglia. We demonstrated that irradiated microglia promote an increase of GBM cell lines proliferation through paracrine signalling. On the contrary, irradiated GBM-derived CM affect viability, triggering cell death mechanisms. In addition, we investigated whether these processes involve mitochondrial mass, fitness and oxidative phosphorylation and how GBM cells respond at these induced alterations. Our study suggests that off-target radiotherapy modulates microglia to support GBM proliferation and induce metabolic modifications.

Ponatinib: A comprehensive drug profile.

Ponatinib is a prescription medication used to treat a rare form of blood cancer called Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic myeloid leukemia (CML) that is resistant to other treatments. It belongs to a class of drugs called tyrosine kinase inhibitors, which work by blocking abnormal proteins that promote the growth of cancer cells. In this chapter, the synthesis methods and physicochemical properties of ponatinib were reviewed, besides the characterization of the ponatinib structure using different techniques such as elemental analysis, IR, UV, (1H and 13C) NMR, MS, and XRD. Furthermore, the compendial method for analysis of ponatinib was not found, while the literature review of a non-compendial method for analysis of ponatinib, such as spectroscopic, chromatographic, and immunoassay methods, was covered. Moreover, pharmacology and biochemistry were surveyed in the pharmacokinetic and pharmacodynamic studies.

Redox Modulation of Meniere Disease by Coriolus Versicolor Treatment, a Nutritional Mushroom Approach with Neuroprotective Potential.

BACKGROUND: Meniere's disease (MD) is a cochlear neurodegenerative disease. Hearing loss appears to be triggered by oxidative stress in the ganglion neurons of the inner ear. OBJECTIVE: Here, we confirm the variation of markers of oxidative stress and inflammation in patients with Meniere and hypothesize that chronic treatment with Coriolus mushroom helps in the response to oxidative stress and acts on α-synuclein and on NF-kB-mediated inflammatory processes. METHODS: Markers of oxidative stress and inflammation were evaluated in MD patients with or without Coriolus treatment for 3 or 6 months. RESULTS: MD patients had a small increase in Nrf2, HO-1, γ-GC, Hsp70, Trx and sirtuin-1, which were further increased by Coriolus treatment, especially after 6 months. Increased markers of oxidative damage, such as protein carbonyls, HNE, and ultraweak chemiluminescence, associated with a decrease in plasma GSH/GSSG ratio, were also observed in lymphocytes from MD patients. These parameters were restored to values similar to the baseline in patients treated with Coriolus for both 3 and 6 months. Furthermore, treated MD subjects showed decreased expression of α-synuclein, GFAP and Iba-1 proteins and modulation of the NF-kB pathway, which were impaired in MD patients. These changes were greatest in subjects taking the supplements for 6 months. CONCLUSIONS: Our study suggests MD as a model of cochlear neurodegenerative disease for the identification of potent inducers of the Nrf2-vitagene pathway, able to reduce the deleterious consequences associated with neurodegenerative damage, probably by indirectly acting on α-synuclein expression and on inflammatory processes NF- kB-mediated.

Polyphenols in Inner Ear Neurobiology, Health and Disease: From Bench to Clinics.

There is substantial experimental and clinical interest in providing effective ways to both prevent and slow the onset of hearing loss. Auditory hair cells, which occur along the basilar membrane of the cochlea, often lose functionality due to age-related biological alterations, as well as from exposure to high decibel sounds affecting a diminished/damaged auditory sensitivity. Hearing loss is also seen to take place due to neuronal degeneration before or following hair cell destruction/loss. A strategy is necessary to protect hair cells and XIII cranial/auditory nerve cells prior to injury and throughout aging. Within this context, it was proposed that cochlea neural stem cells may be protected from such aging and environmental/noise insults via the ingestion of protective dietary supplements. Of particular importance is that these studies typically display a hormetic-like biphasic dose-response pattern that prevents the occurrence of auditory cell damage induced by various model chemical toxins, such as cisplatin. Likewise, the hormetic dose-response also enhances the occurrence of cochlear neural cell viability, proliferation, and differentiation. These findings are particularly important since they confirmed a strong dose dependency of the significant beneficial effects (which is biphasic), whilst having a low-dose beneficial response, whereas extensive exposures may become ineffective and/or potentially harmful. According to hormesis, phytochemicals including polyphenols exhibit biphasic dose-response effects activating low-dose antioxidant signaling pathways, resulting in the upregulation of vitagenes, a group of genes involved in preserving cellular homeostasis during stressful conditions. Modulation of the vitagene network through polyphenols increases cellular resilience mechanisms, thus impacting neurological disorder pathophysiology. Here, we aimed to explore polyphenols targeting the NF-E2-related factor 2 (Nrf2) pathway to neuroprotective and therapeutic strategies that can potentially reduce oxidative stress and inflammation, thus preventing auditory hair cell and XIII cranial/auditory nerve cell degeneration. Furthermore, we explored techniques to enhance their bioavailability and efficacy.

An Ultrafast UPLC-MS/MS Method for Characterizing the In Vitro Metabolic Stability of Acalabrutinib.

Acalabrutinib, commercially known as Calquence®, is a pharmacological molecule that has robust inhibitory activity against Bruton tyrosine kinase. The medicine in question was carefully developed by the esteemed pharmaceutical company AstraZeneca. The FDA granted authorization on 21 November 2019 for the utilization of acalabrutinib (ACB) in the treatment of small lymphocytic lymphoma (SLL) or chronic lymphocytic leukemia (CLL) in adult patients. The aim of this study was to develop a UPLC-MS/MS method that is effective, accurate, environmentally sustainable, and has a high degree of sensitivity. The methodology was specifically developed with the intention of quantifying ACB in human liver microsomes (HLMs). The methodology described above was subsequently utilized to assess the metabolic stability of ACB in HLMs in an in vitro environment. The validation procedures for the UPLC-MS/MS method in the HLMs were conducted in accordance with the bioanalytical method validation criteria established by the U.S.- DA. The utilization of the StarDrop software (version 6.6), which integrates the P450 metabolic module and DEREK software (KB 2018 1.1), was employed for the purpose of evaluating the metabolic stability and identifying potential hazardous alarms associated with the chemical structure of ACB. The calibration curve, as established by the ACB, demonstrated a linear correlation across the concentration range of 1 to 3000 ng/mL in the matrix of HLMs. The present study conducted an assessment of the accuracy and precision of the UPLC-MS/MS method in quantifying inter-day and intra-day fluctuations. The inter-day accuracy demonstrated a spectrum of values ranging from -1.00% to 8.36%, whilst the intra-day accuracy presented a range of values spanning from -2.87% to 4.11%. The t1/2 and intrinsic clearance (Clint) of ACB were determined through in vitro testing to be 20.45 min and 39.65 mL/min/kg, respectively. The analysis concluded that the extraction ratio of ACB demonstrated a moderate level, thus supporting the recommended dosage of ACB (100 mg) to be administered twice daily for the therapeutic treatment of persons suffering from B-cell malignancies. Several computational tools have suggested that introducing minor structural alterations to the butynoyl group, particularly the alpha, beta-unsaturated amide moiety, or substituting this group during the drug design procedure, could potentially enhance the metabolic stability and safety properties of novel derivatives in comparison to ACB.

Hormesis defines the limits of lifespan.

This commentary provides a novel synthesis of how biological systems adapt to a broad spectrum of environmental and age-related stresses that are underlying causes of numerous degenerative diseases and debilitating effects of aging. It proposes that the most fundamental, evolutionary-based integrative strategy to sustain and protect health is based on the concept of hormesis. This concept integrates anti-oxidant, anti-inflammatory and cellular repair responses at all levels of biological organization (i.e., cell, organ and organism) within the framework of biphasic dose responses that describe the quantitative limits of biological plasticity in all cells and organisms from bacteria and plants to humans. A major feature of the hormetic concept is that low levels of biological, chemical, physical and psychological stress upregulate adaptive responses that not only precondition, repair and restore normal functions to damaged tissues/organs but modestly overcompensate, reducing ongoing background damage, thereby enhancing health beyond that in control groups, lacking the low level "beneficial" stress. Higher doses of such stress often become counterproductive and eventually harmful. Hormesis is active throughout the life-cycle and can be diminished by aging processes affecting the onset and severity of debilitating conditions/diseases, especially in elderly subjects. The most significant feature of the hormetic dose response is that the limits of biological plasticity for adaptive processes are less than twice that of control group responses, with most, at maximum, being 30-60 % greater than control group values. Yet, these modest increases can make the difference between health or disease and living or dying. The quantitative features of these adaptive hormetic dose responses are also independent of mechanism. These features of the hormetic dose response determine the capacity to which systems can adapt/be protected, the extent to which biological performance (e.g., memory, resistance to injury/disease, wound healing, hair growth or lifespan) can be enhanced/extended and the extent to which synergistic interactions may occur. Hormesis defines the quantitative rules within which adaptive processes operate and is central to evolution and biology and should become transformational for experimental concepts and study design strategies, public health practices and a vast range of therapeutic strategies and interventions.

Investigation of Fenebrutinib Metabolism and Bioactivation Using MS3 Methodology in Ion Trap LC/MS.

Fenebrutinib is an orally available Bruton tyrosine kinase inhibitor. It is currently in multiple phase III clinical trials for the management of B-cell tumors and autoimmune disorders. Elementary in-silico studies were first performed to predict susceptible sites of metabolism and structural alerts for toxicities by StarDrop WhichP450™ module and DEREK software; respectively. Fenebrutinib metabolites and adducts were characterized in-vitro in rat liver microsomes (RLM) using MS3 method in Ion Trap LC-MS/MS. Formation of reactive and unstable intermediates was explored using potassium cyanide (KCN), glutathione (GSH) and methoxylamine as trapping nucleophiles to capture the transient and unstable iminium, 6-iminopyridin-3(6H)-one and aldehyde intermediates, respectively, to generate a stable adducts that can be investigated and analyzed using mass spectrometry. Ten phase I metabolites, four cyanide adducts, five GSH adducts and six methoxylamine adducts of fenebrutinib were identified. The proposed metabolic reactions involved in formation of these metabolites are hydroxylation, oxidation of primary alcohol to aldehyde, n-oxidation, and n-dealkylation. The mechanism of reactive intermediate formation of fenebrutinib can provide a justification of the cause of its adverse effects. Formation of iminium, iminoquinone and aldehyde intermediates of fenebrutinib was characterized. N-dealkylation followed by hydroxylation of the piperazine ring is proposed to cause the bioactivation to iminium intermediates captured by cyanide. Oxidation of the hydroxymethyl group on the pyridine moiety is proposed to cause the generation of reactive aldehyde intermediates captures by methoxylamine. N-dealkylation and hydroxylation of the pyridine ring is proposed to cause formation of iminoquinone reactive intermediates captured by glutathione. FBB and several phase I metabolites are bioactivated to fifteen reactive intermediates which might be the cause of adverse effects. In the future, drug discovery experiments utilizing this information could be performed, permitting the synthesis of new drugs with better safety profile. Overall, in silico software and in vitro metabolic incubation experiments were able to characterize the FBB metabolites and reactive intermediates using the multistep fragmentation capability of ion trap mass spectrometry.

MemophenolTM Prevents Amyloid-ß Deposition and Attenuates Inflammation and Oxidative Stress in the Brain of an Alzheimer's Disease Rat.

Alzheimer's disease (AD) is the most common cause of dementia, and its prevalence rises with age. Inflammation and altered antioxidant systems play essential roles in the genesis of neurodegenerative diseases. In this work, we looked at the effects of MemophenolTM, a compound rich in polyphenols derived from French grape (Vitis vinifera L.) and wild North American blueberry (Vaccinium angustifolium A.) extracts, in a rat model of AD. Methods: For 60 days, the animals were administered with AlCl3 (100 mg/kg, orally) and D-galactose (60 mg/kg, intraperitoneally), while from day 30, MemophenolTM (15 mg/kg) was supplied orally for 30 consecutive days. AlCl3 accumulates mainly in the hippocampus, the main part of the brain involved in memory and learning. Behavioral tests were performed the day before the sacrifice when brains were collected for analysis. Results: MemophenolTM decreased behavioral alterations and hippocampus neuronal degeneration. It also lowered phosphorylated Tau (p-Tau) levels, amyloid precursor protein (APP) overexpression, and ß-amyloid (Aß) buildup. Furthermore, MemophenolTM reduced the pro-oxidative and pro-inflammatory hippocampus changes caused by AD. Our finding, relevant to AD pathogenesis and therapeutics, suggests that MemophenolTM, by modulating oxidative and inflammatory pathways and by regulating cellular brain stress response mechanisms, protects against the behavioral and histopathological changes associated with AD.

Synthesis, Molecular Docking, c-Met Inhibitions of 2,2,2-Trichloroethylidene- cyclohexane-1, 3-dione Derivatives Together with their Application as Target SARS-CoV-2 main Protease (Mpro) and as Potential anti-COVID-19.

BACKGROUND: The lack of anti-COVID-19 treatment to date warrants urgent research into potential therapeutic targets. Virtual drug screening techniques enable the identification of novel compounds that target the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Main Protease (Mpro). OBJECTIVE: The binding of the halogenated compounds to Mpro may inhibit the replication and transcription of SARS-CoV-2 and, ultimately, stop the viral life cycle. In times of dire need for anti- COVID-19 treatment, this study lays the groundwork for further experimental research to investigate these compounds' efficacy and potential medical uses to treat COVID-19. METHODS: New heterocyclic compounds were synthesized through the first reaction of cyclohexane- 1, 3-dione (1a) or dimedone (1b) with trichloroacetonitrile (2) to give the 2,2,2-trichloroethylidene) cyclohexane-1,3-dione derivatives 3a and 3b, respectively. The latter compounds underwent a series of heterocyclization reactions to produce biologically active compounds. RESULTS: Novel compounds, including fused thiophene, pyrimidine and pyran derivatives, were synthesized and tested against human RNA N7-MTase (hRNMT) and selected viral N7-MTases such as SARS-CoV nsp14 and Vaccinia D1-D12 complex to evaluate their specificity and their molecular modeling was also studied in the aim of producing anti-COVID-19 target molecules. CONCLUSION: The results showed that compounds 10a, 10b, 10c, 10e, 10f, 10g and 10h showed high % inhibitions against SARs-Covnsp 14. Whereas compounds 5a, 7a, 8b, 10a, 10b, 10c and 10i showed high inhibitions against hRNMT. This study explored the binding affinity of twenty-two halogenated compounds to the SARS-CoV-2 MPro and discovered fifteen compounds with higher binding affinity than Nelfinavir, of which three showed remarkable results. c-Met kinase inhibitions of 10a, 10f, 10g and 10h showed that all compounds exhibited higher inhibitions than the reference Foretinib.

Autophagy machinery plays an essential role in traumatic brain injury-induced apoptosis and its related behavioral abnormalities in mice: focus on Boswellia Sacra gum resin.

Traumatic brain injury (TBI) is described as a structural damage or physiological disturbance of brain function that occurs after trauma and causes disability or death in people of all ages. New treatment targets for TBI are being explored because current medicines are frequently ineffectual and poorly tolerated. There is increasing evidence that following TBI, there are widespread changes in autophagy-related proteins in both experimental and clinical settings. The current study investigated if Boswellia Sacra Gum Resin (BSR) treatment (500 mg/kg) could modulate post-TBI neuronal autophagy and protein expression, as well as whether BSR could markedly improve functional recovery in a mouse model of TBI. Taken together our results shows for the first time that BSR limits histological alteration, lipid peroxidation, antioxidant, cytokines release and autophagic flux alteration induced by TBI.

A validated LC-MS/MS analytical method for the quantification of pemigatinib: metabolic stability evaluation in human liver microsomes.

Pemigatinib (PMB) is a small molecule inhibitor of fibroblast growth factor receptor 1 (FGFR1), FGFR2 and FGFR3. On April 17, 2020, the US Food and Drug Administration granted accelerated approval for PMB for the treatment of adults with previously treated, unresectable metastatic or locally advanced cholangiocarcinoma with a fibroblast growth factor receptor 2 (FGFR2) fusion or other rearrangement. PMB is considered the first targeted treatment for cholangiocarcinoma approved in the US. In this study, in silico prediction of PMB metabolic stability was done using the WhichP450 module of the StarDrop software package. Further, an LC-MS/MS analytical method was developed for PMB quantification in human liver microsomes (HLM) to experimentally assess metabolic stability. PMB and flavopiridol (FVL), used as an internal standard IS, were resolved using an isocratic mobile phase and a C18 stationary phase. The LC-MS/MS method showed linearity in the range of 5 to 500 ng mL-1 in an HLM matrix (R 2 = 0.9995). The lower limit of quantification (LLOQ) was 5 ng mL-1, indicating sensitivity. The inter- and intra-day accuracy and precision were within a variability of 10, confirming the reproducibility of the method. The measured in vitro half-life and intrinsic clearance of PMB were 27.29 min and 25.40 µL min-1 mg-1, respectively. PMB showed a moderate extraction ratio suggesting good bioavailability. The developed analytical method is the first LC-MS/MS method specific for PMB quantification with application to metabolic stability assessment.

Estimation of zorifertinib metabolic stability in human liver microsomes using LC-MS/MS.

Zorifertinib (AZD-3759; ZFB) is a novel, potent, oral, small molecule used to treat non-small cell lung cancer. ZFB is an epidermal growth factor receptor inhibitor that is capable of crossing blood-brain barrier. The in silico metabolic software used for ZFB metabolic stability prediction was the StarDrop software package (WhichP450 module). An LC-MS/MS analytical method (fast and accurate) was established for ZFB quantification in human liver microsomes (HLMs) in order to estimate its metabolic stability. ZFB and encorafenib (ENF) (internal standard; IS) were separated through the use of an isocratic mobile phase system with a C8 stationary phase column. The LC-MS/MS method for ZFB exhibited linearity in the range of 5 ng/mL to 500 ng/mL in HLMs matrix with a linear regression equation: y = 0.2438x - 0.341 (R² = 0.9992). The limit of quantification (LOQ) was 3.78 ng/mL confirming the LC-MS/MS method sensitivity. The inter- and intraday accuracy and precision were less than 9.56% confirming the reproducibility of the LC-MS/MS method. The intrinsic clearance and in vitro half-life of ZFB were 32.5 µL/min/mg and 21.33 min, respectively. ZFB exhibited a moderate extraction ratio that revealed good bioavailability. Literature review demonstrated that the developed analytical method is the first developed LC-MS/MS method for determining ZFB metabolic stability.

Development of novel univariate and multivariate validated chemometric methods for the analysis of dasatinib, sorafenib, and vandetanib in pure form, dosage forms and biological fluids.

New precise, responsive and selective univariate and multivariate chemometric spectrophotometric methods were developed and validated for determination of vandetanib (VTB), dasatinib (DTB), and sorafenib (SFB) in pure form, tablets, spiked human (plasma and urine). Determination of these drugs is essential because of their therapeutic benefits. These methods included double divisor ratio spectra derivative univariate method and chemometric multivariate method including partial least-squares (PLS) and principal component regression (PCR). A novel univariate method was developed for the estimation of these drugs. This method depends on the UV-Spectrophotometric data for simultaneous analysis of a ternary overlapped mixture. The Double divisor ratio spectra derivative absorption minima at 358.4 nm was used for quantification of VTB, absorption maxima at 300.3 nm for quantification of DTB and absorption maxima at 259.8 nm for quantification of SFB. This method shown a linearity in the extent of 2-9 µg/mL for VTB and DTB and over the concentration range of 3-9 µg/mL SFB within correlation coefficient (r2) of 0.9999. This method was successfully applied to pure form, tablet dosage form, spiked human (urine and plasma). Chemometric PLS and PCR models were found to be linear in the range of 2-9, 2-9, and 3-9 µg/mL for VTB, DTB and SFB, respectively. These models were estimated using eighteen mixtures as calibration set and seven mixtures as validation set. In the original data, the minimum root mean square error of prediction (RMSEP) was 0.11, 0.09 and 0.09 for VTB, DTB and SFB by PLS and 0.05, 0.04 and 0.03 by PCR while in the derivative data, the RMSEP was 0.09, 0.10 and 0.09 by PLS and 0.06, 0.06 and 0.03, by PCR for VTB, DTB and SFB, respectively. These methods were applied for the determination of the drugs in pure form and dosage form. Updating PLS model permitted the determination of the VTB, DTB and SFB in spiked human urine, plasma and drug-dissolution test of their tablet.

LC-MS/MS Estimation of Rociletinib Levels in Human Liver Microsomes: Application to Metabolic Stability Estimation.

BACKGROUND: Rociletinib (CO-1686; RLC) is a new, small molecule that is orally administered to inhibit mutant-selective covalent inhibitor of most epidermal growth factor receptor (EGFR)-mutated forms, including T790M, L858R, and exon 19 deletions, but not exon 20 insertions. Non-small-cell lung cancer (NSCLC) with a gene mutation that encodes EGFR is sensitive to approved EGFR inhibitors, but usually resistance develops, which is frequently mediated by T790M EGFR mutation. RLC is an EGFR inhibitor found to be active in preclinical models of EGFR-mutated NSCLC with or without T790M. METHODS: In silico drug metabolism prediction of RLC was executed with the aid of the WhichP450 module (StarDrop software package) to verify its metabolic liability. Second, a fast, accurate, and competent LC-MS/MS assay was developed for RLC quantification to determine its metabolic stability. RLC and bosutinib (BOS) (internal standard; IS) were separated using an isocratic elution system with a C18 column (reversed stationary phase). RESULTS: The developed LC-MS/MS analytical method showed linearity of 5-500 ng/mL with r2 ≥ 0.9998 in the human liver microsomes (HLMs) matrix. A limit of quantification of 4.6 ng/mL revealed the sensitivity of the analytical method, while the acquired inter- and intra-day accuracy and precision values below 4.63% inferred the method reproducibility. RLC metabolic stability estimation was calculated using intrinsic clearance (20.15 µL/min/mg) and in vitro half-life (34.39 min) values. CONCLUSION: RLC exhibited a moderate extraction ratio indicative of good bioavailability. The developed analytical method herein is the first LC-MS/MS assay for RLC metabolic stability.

Simple and efficient spectroscopic-based univariate sequential methods for simultaneous quantitative analysis of vandetanib, dasatinib, and sorafenib in pharmaceutical preparations and biological fluids.

Six sequential spectrophotometric-based univariate methods were developed and validated for the simultaneous estimation of three novel anticancer drugs vandetanib (VAN), dasatinib (DAS), and sorafenib (SOR) in a mixture, without the requirement for separation. These methods are novel, simple, precise, and accurate. Different steps including zero crossing, ratio-based, and/or derivative spectra were utilized to develop these analytical methods, namely, ratio difference spectrophotometric method, constant center method, successive derivative ratio method, isoabsorptive method, mean centering of the ratio spectra method, and derivative ratio spectrum-zero crossing method. The calibration curve linearity was ranged from 2 to 9, 2-9, and 3-9 µgmL-1 for VAN, DAS, and SOR, respectively. These established methods were applied for the quantification of the three selected drugs in different biological fluids (spiked human plasma and urine) and pharmaceutical preparations. The aforementioned methods were established for the concurrent estimation of ternary and binary mixtures to enhance the signal-to-noise ratio. The results did not statistically differ from the other reported methods, indicating no significant difference in accuracy and precision at p = 0.05.

Characterization of Stable and Reactive Metabolites of the Anticancer Drug, Ensartinib, in Human Liver Microsomes Using LC-MS/MS: An in silico and Practical Bioactivation Approach.

BACKGROUND: Ensartinib (ESB) is a novel anaplastic lymphoma kinase inhibitor (ALK) with additional activity against Abelson murine leukemia (ABL), met proto-oncogene (MET), receptor tyrosine kinase (AXL), and v-ros UR2 sarcoma virus oncogene homolog 1 (ROS1) and is considered a safer alternative for other ALK inhibitors. ESB chemical structure contains a dichloro-fluorophenyl ring and cyclic tertiary amine rings (piperazine) that can be bioactivated generating reactive intermediates. METHODS: In vitro metabolic study of ESB with human liver microsomes (HLMs) was performed and the hypothesis of generating reactive intermediates during metabolism was tested utilizing trapping agents to capture and stabilize reactive intermediates to facilitate their LC-MS/MS detection. Reduced glutathione (GSH) and potassium cyanide (KCN) were utilized as trapping agents for quinone methide and iminium intermediates, respectively. RESULTS: Four in vitro ESB phase I metabolites were characterized. Three reactive intermediates including one epoxide and one iminium intermediates were characterized. ESB bioactivation is proposed to occur through unexpected metabolic pathways. The piperazine ring was bioactivated through iminium ions intermediates generation, while the dichloro-phenyl group was bioactivated through a special mechanism that was revealed by LC-MS/MS. CONCLUSION: These findings lay the foundations for additional work on ESB toxicity. Substituents to the bioactive centers (piperazine ring), either for blocking or isosteric replacement, would likely block or interrupt hydroxylation reaction that will end the bioactivation sequence.

LC-MS/MS Estimation of the Anti-Cancer Agent Tandutinib Levels in Human Liver Microsomes: Metabolic Stability Evaluation Assay.

PURPOSE: Tandutinib (MLN518 or CT 53518) (TND) is a novel, oral, small-molecule inhibitor of type III receptor tyrosine kinases utilized for the treatment of acute myeloid leukemia (AML). MATERIALS AND METHODS: In silico prediction of hepatic drug metabolism for TND was determined using the StarDrop® WhichP450™ module to confirm its metabolic liability. Second, an efficient and accurate LC-MS/MS method was established for TND quantification to evaluate metabolic stability. TND and entrectinib (ENC) (internal standard; IS) were resolved using an isocratic elution system with a reversed stationary phase (C8 column). RESULTS: The established LC-MS/MS method exhibited linearity (5-500 ng/mL) with r2 ≥0.9999 in the human liver microsomes matrix. The method sensitivity was indicated by the limit of quantification (3.8 ng/mL), and reproducibility was revealed by inter- and intraday precision and accuracy (below 10.5%). TND metabolic stability estimation was calculated using intrinsic clearance (22.03 µL/min/mg) and in vitro half-life (29.0 min) values. CONCLUSION: TND exhibited a moderate extraction ratio indicative of good bioavailability. According to the literature, the approach developed in the present study is the first established LC-MS/MS method for assessing TND metabolic stability.

Identification of Iminium Intermediates Generation in the Metabolism of Tepotinib Using LC-MS/MS: In Silico and Practical Approaches to Bioactivation Pathway Elucidation.

Tepotinib (Tepmetko™, Merck) is a potent inhibitor of c-Met (mesenchymal-epithelial transition factor). In March 2020, tepotinib (TEP) was approved for use in Japan for the treatment of patients who suffered from non-small cell lung cancers (NSCLC) harboring an MET exon 14 skipping alteration and have progressed after platinum-based therapy. Practical and in silico experiments were used to screen for the metabolic profile and reactive intermediates of TEP. Knowing the bioactive center and structural alerts in the TEP structure helped in making targeted modifications to improve its safety. First, the prediction of metabolism vulnerable sites and reactivity metabolic pathways was performed using the StarDrop WhichP450™ module and the online Xenosite reactivity predictor tool, respectively. Subsequently, in silico data were used as a guide for the in vitro practical work. Second, in vitro phase I metabolites of TEP were generated from human liver microsome (HLM) incubations. Testing for the generation of unstable reactive intermediates was performed using potassium cyanide as a capturing agent forming stable cyano adduct that can be characterized and identified using liquid chromatography tandem mass spectrometry (LC-MS/MS). Third, in silico toxicity assessment of TEP metabolites was performed, and structural modification was proposed to decrease their side effects and to validate the proposed bioactivation pathway using the DEREK software. Four TEP phase I metabolites and four cyano adducts were characterized. The reactive intermediate generation mechanism of TEP may provide an explanation of its adverse reactions. The piperidine ring is considered a structural alert for toxicity as proposed by the DEREK software and a Xenosite reactivity model, which was confirmed by practical experiments. Steric hindrance or isosteric replacement at α-carbon of the piperidine ring stop the bioactivation sequence that was confirmed using the DEREK software. More drug discovery studies can be performed using this perception permitting the design of new drugs with an increased safety profile. To our knowledge, this is the first study for the identification of in vitro phase I metabolites and reactive intermediates in addition to toxicological properties of the metabolites for TEP that will be helpful for the evaluation of TEP side effects and drug-drug interactions in TEP-treated patients.

Metabolic Stability Assessment of New PARP Inhibitor Talazoparib Using Validated LC-MS/MS Methodology: In silico Metabolic Vulnerability and Toxicity Studies.

BACKGROUND: Talazoparib (BMN673) is a new poly(ADP-ribose) polymerase inhibitor that has been FDA approved for patients suffering from metastatic breast cancer with germline BRCA mutations. METHOD AND RESULTS: In the current study, an accurate and efficient liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical methodology was developed for TZB estimation in addition to its metabolic stability assessment. TZB and lapatinib (LAP) (which is chosen as an internal standard; IS) were separated using reversed phase elution system (Hypersil C18 column) with an isocratic mobile phase. The linearity range of the established method was 5-500 ng/mL (r2 ≥ 0.999) in the human liver microsomes (HLMs) matrix. Different parameters were calculated to confirm the method sensitivity (limit of quantification was 2.0 ng/mL), and reproducibility (intra- and inter-day precision and accuracy were below 3.1%) of our methodology. For evaluation of TZB metabolic stability in HLM matrix, intrinsic clearance (9.59 µL/min/mg) and in vitro half-life (72.7 mins) were calculated. TZB treatment discontinuations were reported due to adverse events and dose accumulation, so in silico metabolic vulnerability (experimental and in silico) and toxicity assessment (in silico) of TZB were performed utilizing P450 Metabolism and DEREK modules of StarDrop software. CONCLUSION: TZB is slowly metabolized by the liver. TZB was reported to be minimally metabolized by the liver that approved our outcomes. We do recommend that plasma levels be monitored in cases when talazoparib is used for a long period of time, since it is possible for TZB to bioaccumulate after multiple doses to toxic levels. According to our knowledge, the current method is considered the first LC-MS/MS methodology for evaluating TZB metabolic stability. Further drug discovery studies can be done depending on this concept allowing the designing of new series of compounds with more safety profile through reducing side effects and improving metabolic behavior.