Ion Trap LC/MS reveals the generation of reactive intermediates in acalabrutinib metabolism: phase I metabolic profiling and bioactivation pathways elucidation

Acalabrutinib (CALQUENCE; ACB) is a Bruton tyrosine kinase inhibitor (BTKI) used to treat mantle cell lymphoma, small lymphocytic lymphoma (SLL), and chronic lymphocytic leukemia (CLL). On 21 November 2019, ACB was approved by the U.S. FDA for the use as a single therapy for the treatment of CLL/SLL. In silico studies were first done to propose vulnerable sites of metabolism and reactivity pathways by StarDrop software and Xenosite online software; respectively. ACB metabolites and stable adducts were characterized in vitro from rat liver microsomes (RLMs) using Ion Trap LC/MS. Generation of reactive intermediates (RIs) in the in vitro metabolism of ACB was investigated using glutathione, potassium cyanide, and methoxylamine as trapping nucleophiles for the RIs including iminopyridinone, iminium, and aldehyde, respectively, to form stable adducts that can be identified and characterized by Ion Trap LC/MS. Five phase I metabolites, seven 6-iminopyridin-3(6H)-one and five aldehyde RIs of ACB were identified. Based on literature reviews, the generation of RIs of ACB, and the subsequent drug-induced organ toxicity (DIOT) reactions may provide an explanation of ACB ADRs. Additional drug discovery investigations can be performed to facilitate the creation of novel medications with improved safety characteristics.

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.

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.

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.

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.

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.

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-β 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 Memophenol^TM, 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, Memophenol^TM (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: Memophenol^TM decreased behavioral alterations and hippocampus neuronal degeneration. It also lowered phosphorylated Tau (p-Tau) levels, amyloid precursor protein (APP) overexpression, and β-amyloid (Aβ) buildup. Furthermore, Memophenol^TM reduced the pro-oxidative and pro-inflammatory hippocampus changes caused by AD. Our finding, relevant to AD pathogenesis and therapeutics, suggests that Memophenol^TM, by modulating oxidative and inflammatory pathways and by regulating cellular brain stress response mechanisms, protects against the behavioral and histopathological changes associated with AD.

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.

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 (R² = 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.

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.

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.

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.

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.

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.

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.

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.

Phase I metabolic profiling and unexpected reactive metabolites in human liver microsome incubations of X-376 using LC-MS/MS: bioactivation pathway elucidation and in silico toxicity studies of its metabolites

Metabolites of X-376 were characterized by LC-MS/MS. Pyridazine ring and dichloro-phenyl groups were bioactivated by novel pathways.

Azilsartan medoxomil

Azilsartan is used for treatment of the high blood pressure (hypertension). Reducing high blood pressure enables avoid strokes, heart attacks and problems of kidneys. Azilsartan comes under the name angiotensin receptor blocker (ARBs) as a class of drugs. It acts by relaxing blood vessels to make it easier for blood to flow. Azilsartan Medoxomil's a comprehensive profile containing the description, formulae, Elemental Analysis, Uses and application. Furthermore, methods and schemes are outlined for the preparation of the drug substance. The physical properties of the medication include constant of ionization, solubility, X-ray powder diffraction pattern, differential scanning calorimetry, thermal conduct and spectroscopic studies are investigated. The methods employed in bulk medicines and/or in pharmaceutical formulations to analyze the drug substance include spectrophotometric, electrochemical and the chromatographic methods. Other studies on this drug substance include drug stability, Pharmaceutical Applications, Mechanism of Action, Pharmacodynamics, and a Dosing Information are reviewed. At the end of this profile, there are more than sixty references were listed.

Detection and characterization of olmutinib reactive metabolites by LC-MS/MS: Elucidation of bioactivation pathways

Olmutinib (Olita™) is an orally bioavailable third generation epidermal growth factor receptor tyrosine kinase inhibitor. Olmutinib was approved in South Korea in May 2016 for the treatment of patients suffering from locally advanced or metastatic epidermal growth factor receptor T790M mutation-positive non-small cell lung cancer. Reactive olmutinib intermediates may be responsible for the severe side effects associated with the treatment. However, literature review revealed no previous reports on the structural identification of reactive olmutinib metabolites. In this work, the formation of reactive olmutinib metabolites in rat liver microsomes was investigated. Methoxylamine, glutathione, and potassium cyanide were used as capturing agents for aldehyde, iminoquinones, and iminium intermediates, respectively. The stable complexes formed were identified using liquid chromatography-tandem mass spectrometry. The major phase I metabolic pathway observed in vitro was hydroxylation of the piperazine ring. Seven potential reactive intermediates were characterized, including three iminium ions, three iminoquinones, and one aldehyde. Based on the findings, various bioactivation pathways were postulated. Hence, identifying the reactive intermediates of olmutinib that may be the cause of severe side effects can provide new insights, leading to improved treatments for patients.

Antiproliferative activity and possible mechanism of action of certain 5-methoxyindole tethered C-5 functionalized isatins

Background

Cancer is one of the most dreaded human diseases, that has become an ever-increasing health problem and is a prime cause of death globally. The potential antiproliferative activity of certain indole-isatin molecular hybrids 5a-w was evaluated in vitro against three human cancer cell lines.

Methods

Standard protocols were adopted to examine the antiproliferative potential and mechanisms of compounds 5a-w. Western blot analysis was carried out on compound 5o.

Results

Compounds 5a-w demonstrated in vitro antiproliferative activity in the range of 22.6-97.8%, with compounds 5o and 5w being the most active antiproliferative compounds   with IC₅₀ values of 1.69 and 1.91 µM, which is fivefold and fourfold more potent than sunitinib (IC₅₀=8.11 µM), respectively. Compound 5o was selected for in-depth pharmacological testing to understand its possible mechanism of antiproliferative activity. It caused a lengthening of the G1 phase and a reduction in the S and G2/M phases of the cell cycle and had an IC₅₀ value of 10.4 μM with the resistant NCI-H69AR cancer cell line. Moreover, compound 5o significantly decreased the amount of phosphorylated Rb protein in a dose-dependent fashion, which was confirmed via Western blot analysis.

Conclusion

The current investigation highlighted the potential antiproliferative activity of compounds 5a-w as well as the antiproliferative profile of compound 5o. These compounds can be harnessed as new lead antiproliferatives in the preclinical studies of cancer chemotherapy.

Liquid chromatography-tandem mass spectrometry metabolic profiling of nazartinib reveals the formation of unexpected reactive metabolites

Nazartinib (EGF816, NZB) is a promising third-generation human epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor. This novel irreversible mutant-selective EGFR inhibitor targets EGFR containing both the resistance mutation (T790M) and the activating mutations (L858R and Del19), while it does not affect wild-type EGFR. However, the metabolic pathway and bioactivation mechanisms of NZB are still unexplored. Thus, using liquid chromatography-tandem mass spectrometry, we screened for products of NZB metabolism formed in vitro by human liver microsomal preparations and investigated the formation of reactive intermediates using potassium cyanide as a nucleophile trap. Unexpectedly, the azepane ring was not bioactivated. Instead, the carbon atom between the aliphatic linear tertiary amine and electron-withdrawing system (butenoyl amide group) was bioactivated, generating iminium intermediates as reactive species. Six NZB phase I metabolites, formed by hydroxylation, oxidation and N-demethylation, were characterized. Moreover, two reactive iminium ions were characterized and their corresponding bioactivation mechanisms were proposed. Based on our results, we speculate that bioactivation of NZB can be blocked by small sterically hindering groups, isosteric replacement or a spacer. This approach might reduce the toxicity of NZB by avoiding the generation of reactive species.

Liquid chromatography-tandem mass spectrometry metabolic profiling of nazartinib reveals the formation of unexpected reactive metabolites

Nazartinib (EGF816, NZB) is a promising third-generation human epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor. This novel irreversible mutant-selective EGFR inhibitor targets EGFR containing both the resistance mutation (T790M) and the activating mutations (L858R and Del19), while it does not affect wild-type EGFR. However, the metabolic pathway and bioactivation mechanisms of NZB are still unexplored. Thus, using liquid chromatography-tandem mass spectrometry, we screened for products of NZB metabolism formed in vitro by human liver microsomal preparations and investigated the formation of reactive intermediates using potassium cyanide as a nucleophile trap. Unexpectedly, the azepane ring was not bioactivated. Instead, the carbon atom between the aliphatic linear tertiary amine and electron-withdrawing system (butenoyl amide group) was bioactivated, generating iminium intermediates as reactive species. Six NZB phase I metabolites, formed by hydroxylation, oxidation and N-demethylation, were characterized. Moreover, two reactive iminium ions were characterized and their corresponding bioactivation mechanisms were proposed. Based on our results, we speculate that bioactivation of NZB can be blocked by small sterically hindering groups, isosteric replacement or a spacer. This approach might reduce the toxicity of NZB by avoiding the generation of reactive species.

A highly sensitive LC-MS/MS method to determine novel Bruton's tyrosine kinase inhibitor spebrutinib: application to metabolic stability evaluation

Spebrutinib (SBT) is a Bruton's tyrosine kinase inhibitor. SBT is currently in phase II and phase I clinical trials for the management of rheumatoid arthritis and chronic lymphocytic leukaemia, respectively. We developed and validated a liquid chromatography tandem mass spectrometry analytical method to quantify SBT and investigate its metabolic stability. SBT and the naquotinib as internal standard were isocratically eluted on a C18 column. The linearity of the developed method is 5-500 ng ml-1 (r2 ≥ 0.9999) in the human liver microsomes (HLMs) matrix. Good sensitivity was approved by the very low limit of detection (0.39 ng ml-1). Inter- and intra-assay accuracy values of -1.41 to 12.44 and precision values of 0.71% to 4.78%, were obtained. SBT was found to have an in vitro half-life (82.52 min) and intrinsic clearance (8.4 µl min-1 mg-1) as computed following its incubation with HLMs. The latter finding, hypothesize that SBT could be slowly excreted from the body unlike other related tyrosine kinase inhibitors. So, drug plasma level and kidney function should be monitored because of potential bioaccumulation. To the best of our knowledge, this is considered the first analytical method for SBT quantification using LC-MS/MS with application to metabolic stability evaluation.

Validated LC-MS/MS assay for quantification of the newly approved tyrosine kinase inhibitor, dacomitinib, and application to investigating its metabolic stability

Dacomitinib (DMB) is a second-generation irreversible tyrosine kinase inhibitor (TKI) that is claimed to overcome the disadvantages of the resistance reported for first-line epidermal growth factor receptor (EGFR) TKIs. Towards the end of 2018, the US Food and Drug Administration approved DMB in the form of VIZIMPRO tablets. In the current study, a validated LC-MS/MS assay was established for DMB quantification in rat liver microsomes (RLMs) with application to the drug metabolic stability assessment. Chromatographic resolution of DMB and lapatinib (internal standard) was achieved using an isocratic mobile phase and a reversed-phase C18 column. The linearity of the established LC-MS/MS assay ranged from 2 to 500 ng/mL with r2 ≥ 0.9999. The limit of detection (LOD) and limit of quantification (LOQ) were 0.35 and 1.1 ng/mL, respectively. The precision and accuracy (both intra-day and inter-day) were 0.84-3.58% and 92.2-100.32%, respectively. The metabolic stability of DMB in the RLM matrix was estimated by calculating two parameters, in vitro t1/2 (0.97 mL/min/kg) and intrinsic clearance (157.5 min). Such values infer that DMB would be excreted very slowly from the human body, which might lead to possible bioaccumulation. To the best of our knowledge, this is the first method for DMB analysis in RLMs with metabolic stability estimation.

A simple liquid chromatography-tandem mass spectrometry method to accurately determine the novel third-generation EGFR-TKI naquotinib with its applicability to metabolic stability assessment

Naquotinib (ASP8273, NQT) is a novel third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKIs). NQT was found to be more effective than osimertinib against the EGFR L858R plus T790M mutation (L858R+T790M). A rapid resolution liquid chromatography (RRLC)-tandem mass spectrometry (MS/MS) method was developed and validated for NQT quantification and its metabolic stability was investigated. NQT and foretinib (FTB) as an internal standard (IS) were separated using a mobile phase under isocratic conditions with a C18 column (reversed phase system). The linearity of the analytical method ranged from 5 to 500 ng mL⁻¹ (coefficient of correlation [r²] ≥ 0.9999) in a human liver microsome (HLM) matrix. The limit of detection and limit of quantification were 0.78 and 2.36 ng mL⁻¹, respectively. The inter-day and intra-day accuracy and precision were −6.36 to 1.88 and 0.99 to 2.58%, respectively. The metabolic stability of NQT in the HLM matrix was calculated using the in vitro half-life (t_1/2, 67.96 min) and intrinsic clearance (Cl_int, 2.12 mL min⁻¹ kg⁻¹). NQT is considered to be a moderate extraction ratio drug that is moderately excreted from the human body compared with other related TKIs. This proposed methodology is thought to be the first method for assessing NQT concentration and its metabolic stability.

The first established LC-MS/MS method for NQT analysis. NQT was shown to be moderately excreted from the human body.

Reactive intermediates in copanlisib metabolism identified by LC-MS/MS: phase I metabolic profiling

Copanlisib (CNB; Aliqopa™) is a novel, intravenous phosphoinositide 3-kinase inhibitor used to treat various solid and hematological malignancies. CNB was recently approved by the U.S. FDA to treat adults that relapsed after two preceding systemic therapies. Using LC-MS/MS, we screened for the in vitro metabolites of CNB formed in human liver microsomes (HLMs) and probed for the generation of reactive electrophiles using methoxyamine and potassium cyanide as nucleophiles to capture reactive electrophiles by forming stable adducts that are suitable for identification by LC-MS/MS. Seven CNB phase I metabolites generated by oxidation, hydroxylation, oxidative dealkylation, reduction, and N-oxidation were identified. In addition, four reactive electrophiles, 2 aldehydes and 2 iminium ions, were identified, and a prediction of the corresponding bioactivation mechanism is presented. The formation of reactive metabolites may be associated with the side effects reported for CNB. To our knowledge, this is the first report on the detailed structural characterization of reactive intermediates generated in CNB metabolism.

Copanlisib (CNB; Aliqopa™) is a novel, intravenous phosphoinositide 3-kinase inhibitor used to treat various solid and hematological malignancies.

Reactive intermediates and bioactivation pathways characterization of avitinib by LC-MS/MS: In vitro metabolic investigation

Avitinib (AC0010) is a third generation inhibitor of the EGFR (epidermal growth factor receptor) that was permitted parallel phase I clinical trials in the US and in 2014. It is estimated to enter in market within two years. In the current study, eight in vitro metabolites were detected and their chemical structures were postulated. The main in vitro phase-I metabolic reaction was N-oxidation in piperazine moiety. The generation of reactive metabolites in avitinib metabolism was investigated using rat liver microsomes while adding capturing agents, viz potassium cyanide for reactive iminium intermediates, GSH for iminoquinones and methoxylamine for aldehyde forming stable adducts which are identifiable by LC-MS/MS. Ten reactive intermediates (four iminoquinones, three iminium and three aldehydes) were characterized. The three capturing agents used resulted in proposing four different bioactivation pathways. Upon literature examination, no former articles were found for avitinib metabolism including the produced reactive metabolites.

Characterization of reactive intermediates formation in dacomitinib metabolism and bioactivation pathways elucidation by LC-MS/MS: in vitro phase I metabolic investigation

Dacomitinib (DCB) is a second generation irreversible tyrosine kinase inhibitor (TKI) that is claimed to overcome the disadvantages of the resistance developed by the first line epidermal growth factor receptor (EGFR) TKIs. In the current study, metabolites of phase I for DCB were systematically explored. DCB reactive metabolites were also investigated in rat liver microsomes in presence of potassium cyanide or methoxylamine that were employed as capturing agents for iminium reactive intermediates and aldehyde, respectively, to form stable complexes which can be detected by LC-MS/MS. As a result, four in vitro phase I metabolites were observed with major pathway of piperidine ring hydroxylation. Additionally, two potentially reactive intermediates, one aldehyde and one iminium ions were characterized. Two different pathways of bioactivation were ultimately proposed.

Investigation of the metabolic stability of olmutinib by validated LC-MS/MS: quantification in human plasma

Olmutinib (OTB, Olita™) is an orally available third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI). It was developed by Boehringer Ingelheim and Hanmi Pharmaceutical Co. Ltd for the cure of non-small cell lung cancer (NSCLC). In May 2016, OTB was approved in South Korea for the treatment of patients suffering from metastatic or locally advanced EGFR T790M mutation-positive NSCLC. A LC-MS/MS methodology was validated for OTB quantification in human plasma. An extended application for this validated LC-MS/MS is OTB metabolic stability evaluation. Chromatographic separation of OTB and ponatinib (PNT, IS) was attained using a reversed phase with isocratic elution. The linearity of the developed LC-MS/MS method ranged from 5.00 to 500.00 ng mL⁻¹ with r² ≥ 0.9999 in human plasma. LOD and LOQ were 1.12 and 3.39 ng mL⁻¹, respectively. The intra-day and inter-day precision and accuracy were 1.17 to 2.75% and 97.86 to 101.48%, respectively. The intrinsic clearance (CL_int) was 2.71 mL min⁻¹ kg⁻¹ and the in vitro half-life (t_1/2) was 48.80 min. A review of the literature revealed that there are no previous articles about the quantification of OTB in human plasma using LC-MS/MS or its metabolic stability assessment.

Olmutinib (OTB, Olita™) is an orally available third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI).

Isatin-benzoazine molecular hybrids as potential antiproliferative agents: synthesis and in vitro pharmacological profiling

In continuation of our endeavor with respect to the development of potent and effective isatin-based anticancer agents, we adopted the molecular hybridization approach to design and synthesize four different sets of isatin-quinazoline (6a-f and 7a-e)/phthalazine (8a-f)/quinoxaline (9a-f) hybrids. The antiproliferative activity of the target hybrids was assessed towards HT-29 (colon), ZR-75 (breast) and A-549 (lung) human cancer cell lines. Hybrids 8b-d emerged as the most active antiproliferative congener in this study. Compound 8c induced apoptosis via increasing caspase 3/7 activity by about 5-fold in the A-549 human cancer cell line. In addition, it exhibited an increase in the G1 phase and a decrease in the S and G2/M phases in the cell cycle effect assay. Furthermore, it displayed an inhibitory concentration 50% value of 9.5 µM against multidrug-resistant NCI-H69AR lung cancer cell line. The hybrid 8c was also subjected to in vitro metabolic investigations through its incubation with rat liver microsomes and analysis of the resulting metabolites with the aid of liquid chromatography-mass spectrometry.

Fluorescence spectroscopic and molecular docking studies of the binding interaction between the new anaplastic lymphoma kinase inhibitor crizotinib and bovine serum albumin

Binding of the recently introduced anti-cancer drug, crizotinib (CRB) with the bovine serum albumin (BSA) was comprehensively studied with the aid of fluorescence and UV-Vis spectroscopic as well as molecular docking techniques. The collective results of the study under the simulated physiological conditions proposed a static type of binding occurring between the CRB and BSA with binding constants of 10⁴Lmol^-1. BSA conformational changes were investigated using three dimensional (3D) and synchronous fluorescence measurements. Moreover, the results of site marker competitive experiments and molecular docking, it could be deduced that CRB was inserted into the subdomain IIA (site I) of BSA yielding a more stabilized system. This was further confirmed with the molecular docking results which revealed that CRB is located in the active site residues Try149, Glu152, Ser191, Arg194, Arg198, Trp213, Arg217, Arg256, His287, Ala290, Glu291, Ser343, Asp450 within a radius of 6Å. Combining the molecular docking studies and the computed thermodynamic parameters, it can be inferred that hydrophobic and electrostatic interactions are the major binding forces involved in formation of the CRB-BSA complex.

Simultaneous quantitative analysis of olmesartan, amlodipine and hydrochlorothiazide in their combined dosage form utilizing classical and alternating least squares based chemometric methods

Simultaneous spectrophotometric analysis of a multi-component dosage form of olmesartan, amlodipine and hydrochlorothiazide used for the treatment of hypertension has been carried out using various chemometric methods. Multivariate calibration methods include classical least squares (CLS) executed by net analyte processing (NAP-CLS), orthogonal signal correction (OSC-CLS) and direct orthogonal signal correction (DOSC-CLS) in addition to multivariate curve resolution-alternating least squares (MCR-ALS). Results demonstrated the efficiency of the proposed methods as quantitative tools of analysis as well as their qualitative capability. The three analytes were determined precisely using the aforementioned methods in an external data set and in a dosage form after optimization of experimental conditions. Finally, the efficiency of the models was validated via comparison with the partial least squares (PLS) method in terms of accuracy and precision.

A new method to determine the new C-Met inhibitor “Cabozantinib” in dosage form and human plasma via micelle-enhanced spectrofluorimetry

A highly sensitive and simple micelle-enhanced spectrofluorimetric method was developed for the determination of cabozantinib (CBZ) in its pharmaceutical formulation and spiked human plasma without any derivatization.

A Stability-Indicating HPLC-DAD Method for Determination of Stiripentol: Development, Validation, Kinetics, Structure Elucidation and Application to Commercial Dosage Form

A rapid, simple, sensitive, and accurate isocratic reversed-phase stability-indicating high performance liquid chromatography method has been developed and validated for the determination of stiripentol and its degradation product in its bulk form and pharmaceutical dosage form. Chromatographic separation was achieved on a Symmetry C18 column and quantification was achieved using photodiode array detector (DAD). The method was validated in accordance with the ICH requirements showing specificity, linearity (r (2) = 0.9996, range of 1-25 μg/mL), precision (relative standard deviation lower than 2%), accuracy (mean recovery 100.08 ± 1.73), limits of detection and quantitation (LOD = 0.024 and LOQ = 0.081 μg/mL), and robustness. Stiripentol was subjected to various stress conditions and it has shown marked stability under alkaline hydrolytic stress conditions, thermal, oxidative, and photolytic conditions. Stiripentol degraded only under acidic conditions, forming a single degradation product which was well resolved from the pure drug with significantly different retention time values. This degradation product was characterized by (1)H-NMR and (13)C-NMR spectroscopy as well as ion trap mass spectrometry. The results demonstrated that the method would have a great value when applied in quality control and stability studies for stiripentol.

Comparative ANNs with different input layers and GA-PLS study for simultaneous spectrofluorimetric determination of melatonin and pyridoxine HCl in the presence of melatonin’s main impurity

Melatonin (MLT) has many health implications, therefore it is important to develop specific analytical methods for the determination of MLT in the presence of its main impurity, N-{2-[1-({3-[2-(acetylamino)ethyl]-5-methoxy-1H-indol-2-yl}methyl)-5-methoxy-1H-indol-3-yl]ethyl}acetaamide (DMLT) and pyridoxine HCl (PNH) as a co-formulated drug. This work describes simple, sensitive, and reliable four multivariate calibration methods, namely artificial neural network preceded by genetic algorithm (GA-ANN), principal component analysis (PCA-ANN) and wavelet transform procedures (WT-ANN) as well as partial least squares preceded by genetic algorithm (GA-PLS) for the spectrofluorimetric determination of MLT and PNH in the presence of DMLT. Analytical performance of the proposed methods was statistically validated with respect to linearity, accuracy, precision and specificity. The proposed methods were successfully applied for the assay of MLT in laboratory prepared mixtures containing up to 15% of DMLT and in commercial MLT tablets with recoveries of no less than 99.00%. No interference was observed from common pharmaceutical additives and the results compared favorably with those obtained by a reference method.