Evaluation of metabolism and disposition of GDC-0152 in rats using 14C labeling strategy at two different positions: a novel formation of hippuric acid from 4-phenyl-5-amino-1,2,3-thiadiazole

Bioactivation and reactivity research advances - 2023 year in review

Advances in the field of bioactivation have significantly contributed to our understanding and prediction of drug-induced liver injury (DILI). It has been established that many adverse drug reactions, including DILI, are associated with the formation and reactivity of metabolites. Modern methods allow us to detect and characterize these reactive metabolites in earlier stages of drug development, which helps anticipate and circumvent the potential for DILI. Improved in silico models and experimental techniques that better reflect in vivo environments are enhancing predictive capabilities for DILI risk. Further, studies on the mechanisms of bioactivation, including enzyme interactions and the role of individual genetic differences, have provided valuable insights for drug optimizations. Cumulatively, this progress is continually refining our approaches to drug safety evaluation and personalized medicine.

The Importance of Tracking "Missing" Metabolites: How and Why?

Technologies currently employed to find and identify drug metabolites in complex biological matrices generally yield results that offer a comprehensive picture of the drug metabolite profile. However, drug metabolites can be missed or are captured only late in the drug development process. This could be due to a variety of factors, such as metabolism that results in partial loss of the molecule, covalent bonding to macromolecules, the drug being metabolized in specific human tissues, or poor ionization in a mass spectrometer. These scenarios often draw a great deal of attention from chemistry, safety assessment, and pharmacology. This review will summarize scenarios of missing metabolites, why they are missing, and associated uncovering strategies from deeper investigations. Uncovering previously missed metabolites can have ramifications in drug development with toxicological and pharmacological consequences, and knowledge of these can help in the design of new drugs.

1-Aminobenzotriazole: A Mechanism-Based Cytochrome P450 Inhibitor and Probe of Cytochrome P450 Biology

1-Aminobenzotriazole (1-ABT) is a pan-specific, mechanism-based inactivator of the xenobiotic metabolizing forms of cytochrome P450 in animals, plants, insects, and microorganisms. It has been widely used to investigate the biological roles of cytochrome P450 enzymes, their participation in the metabolism of both endobiotics and xenobiotics, and their contributions to the metabolism-dependent toxicity of drugs and chemicals. This review is a comprehensive evaluation of the chemistry, discovery, and use of 1-aminobenzotriazole in these contexts from its introduction in 1981 to the present.

Glucuronidation: driving factors and their impact on glucuronide disposition

Glucuronidation is a well-recognized phase II metabolic pathway for a variety of chemicals including drugs and endogenous substances. Although it is usually the secondary metabolic pathway for a compound preceded by phase I hydroxylation, glucuronidation alone could serve as the dominant metabolic pathway for many compounds, including some with high aqueous solubility. Glucuronidation involves the metabolism of parent compound by UDP-glucuronosyltransferases (UGTs) into hydrophilic and negatively charged glucuronides that cannot exit the cell without the aid of efflux transporters. Therefore, elimination of parent compound via glucuronidation in a metabolic active cell is controlled by two driving forces: the formation of glucuronides by UGT enzymes and the (polarized) excretion of these glucuronides by efflux transporters located on the cell surfaces in various drug disposition organs. Contrary to the common assumption that the glucuronides reaching the systemic circulation were destined for urinary excretion, recent evidences suggest that hepatocytes are capable of highly efficient biliary clearance of the gut-generated glucuronides. Furthermore, the biliary- and enteric-eliminated glucuronides participate into recycling schemes involving intestinal microbes, which often prolong their local and systemic exposure, albeit at low systemic concentrations. Taken together, these recent research advances indicate that although UGT determines the rate and extent of glucuronide generation, the efflux and uptake transporters determine the distribution of these glucuronides into blood and then to various organs for elimination. Recycling schemes impact the apparent plasma half-life of parent compounds and their glucuronides that reach intestinal lumen, in addition to prolonging their gut and colon exposure.

GDC-0152 attenuates the malignant progression of osteosarcoma promoted by ANGPTL2 via PI3K/AKT but not p38MAPK signaling pathway

Angiopoietin-like protein 2 (ANGPTL2) plays an important role in inflammatory carcinogenesis and tumor metastasis. The compound GDC-0152 is a peptidomimetic small molecule antagonist of inhibitor of apoptosis (IAP) proteins with antitumor activity. However, the interaction between ANGPTL2 and GDC-0152 has not been studied. It has been proven that ANGPTL2 promotes metastasis of osteosarcoma. Therefore, in the present study, the effect of GDC-0152 on the malignant progression of osteosarcoma promoted by ANGPTL2 was investigated. Human osteosarcoma cell line SaOS2 cells were pre-treated or non-treated with GDC-0152 and then exposed to recombinant human ANGPTL2. The viability of SaOS2 cells was determined by MTT assay, the migration of SaOS2 cells was analyzed by chamber migration assay kit, and the SaOS2 cell apoptosis was determined by fluorescence-activated cell sorting (FACS) and nuclear staining. Treatment with ANGPTL2 increased SaOS2 cell growth and migration and decreased cell apoptosis. The increased cell growth and decreased cell apoptosis were significantly attenuated in SaOS2 cells receiving GDC-0152. However, the ANGPTL2-increased SaOS2 cell migration was not inhibited by GDC-0152 treatment. Furthermore, western blot analysis showed that the activation of phosphatidyl inositol 3-kinase (PI3K) (p85), PI3K (p110), protein kinase B (Akt) (Ser473), Akt (Thr308) and p38 mitogen-activated protein kinase (p38MAPK) were upregulated by ANGPTL2. Quantitative real-time polymerase chain reaction (qTR-PCR) and gelatin zymography showed that the mRNA expression and activity of matrix metalloproteinase-9 (MMP-9) and matrix metalloproteinase-2 (MMP-2) were also increased by ANGPTL2. The upregulated activation of PI3K and Akt were significantly suppressed by the treatment of GDC-0152. In contrast, GDC-0152 did not suppress ANGPTL2-induced p38MAPK phosphorylation, MMP-9/MMP-2 mRNA expression or MMP-9/MMP-2 activity. Taken together, these data indicate that GDC-0152 attenuates the malignant progression of osteosarcoma promoted by ANGPTL2 via PI3K/AKT but not p38MAPK signaling pathway. The present study indicated a novel therapeutic strategy to inhibit tumor growth by indirectly preventing ANGPTL2 signaling.

Autoradiography techniques and quantification of drug distribution

The use of radiolabeled drug compounds offers the most efficient way to quantify the amount of drug and/or drug-derived metabolites in biological samples. Autoradiography is a technique using X- ray film, phosphor imaging plates, beta imaging systems, or photo-nuclear emulsion to visualize molecules or fragments of molecules that have been radioactively labeled, and it has been used to quantify and localize drugs in tissues and cells for decades. Quantitative whole-body autoradiography or autoradioluminography (QWBA) using phosphor imaging technology has revolutionized the conduct of drug distribution studies by providing high resolution images of the spatial distribution and matching tissue concentrations of drug-related radioactivity throughout the body of laboratory animals. This provides tissue-specific pharmacokinetic (PK) compartmental analysis which has been useful in toxicology, pharmacology, and drug disposition/patterns, and to predict human exposure to drugs and metabolites, and also radioactivity, when a human radiolabeled drug study is necessary. Microautoradiography (MARG) is another autoradiographic technique that qualitatively resolves the localization of radiolabeled compounds to the cellular level in a histological preparation. There are several examples in the literature of investigators attempting to obtain drug concentration data from MARG samples; however, there are technical issues which make that problematic. These issues will be discussed. This review will present a synopsis of both techniques and examples of how they have been used for drug research in recent years.

GDC-0152 induces apoptosis through down-regulation of IAPs in human leukemia cells and inhibition of PI3K/Akt signaling pathway

The inhibitor of apoptosis proteins (IAPs) is closely related to leukemia apoptosis. The present study was undertaken to determine the molecular mechanisms by which GDC-0152, an IAP inhibitor, induces apoptosis in human leukemia cells (K562 and HL60 cells). GDC-0152 inhibited the proliferation of K562 and HL60 cells in a dose- and time-dependent manner, which was largely attributed to intrinsic apoptosis. GDC-0152 down-regulated the IAPs including X-linked inhibitor of apoptosis protein (XIAP), cellular inhibitor of apoptosis protein-1 (cIAP1), and cellular inhibitor of apoptosis protein-2 (cIAP2) expression and induced the activation of caspase-9 and caspase-3. GDC-0152-induced cell proliferation inhibition in K562 cells was prevented by pan-caspase inhibitor. GDC-0152 also inhibited PI3K and Akt expression in K562 and HL60 cells. Taken together, these findings suggest that GDC-0152 results in human leukemia apoptosis through caspase-dependent mechanisms involving down-regulation of IAPs and inhibition of PI3K/Akt signaling.

Learning and confirming with preclinical studies: modeling and simulation in the discovery of GDC-0917, an inhibitor of apoptosis proteins antagonist

The application of modeling and simulation techniques is increasingly common in the preclinical stages of the drug development process. GDC-0917 [(S)-1-((S)-2-cyclohexyl-2-((S)-2-(methylamino)propanamido)acetyl)-N-(2-(oxazol-2-yl)-4-phenylthiazol-5-yl)pyrrolidine-2-carboxamide] is a potent second-generation antagonist of inhibitor of apoptosis (IAP) proteins that is being developed for the treatment of various cancers. GDC-0917 has low to moderate clearance in the mouse (12.0 ml/min/kg), rat (27.0 ml/min/kg), and dog (15.3 ml/min/kg), and high clearance in the monkey (67.6 ml/min/kg). Accordingly, oral bioavailability was lowest in monkeys compared with other species. Based on our experience with a prototype molecule with similar structure, in vitro-in vivo extrapolation was used to predict a moderate clearance (11.5 ml/min/kg) in humans. The predicted human volume of distribution was estimated using simple allometry at 6.69 l/kg. Translational pharmacokinetic-pharmacodynamic (PK-PD) analysis using results from MDA-MB-231-X1.1 breast cancer xenograft studies and predicted human pharmacokinetics suggests that ED50 and ED90 targets can be achieved in humans using acceptable doses (72 mg and 660 mg, respectively) and under an acceptable time frame. The relationship between GDC-0917 concentrations and pharmacodynamic response (cIAP1 degradation) was characterized using an in vitro peripheral blood mononuclear cell immunoassay. Simulations of human GDC-0917 plasma concentration-time profile and cIAP1 degradation at the 5-mg starting dose in the phase 1 clinical trial agreed well with observations. This work shows the importance of leveraging information from prototype molecules and illustrates how modeling and simulation can be used to add value to preclinical studies in the early stages of the drug development process.