Calculation of an Apical Efflux Ratio from P-Glycoprotein (P-gp) In Vitro Transport Experiments Shows an Improved Correlation with In Vivo Cerebrospinal Fluid Measurements in Rats: Impact on P-gp Screening and Compound Optimization

Fischer, Holger; Senn, Claudia; Ullah, Mohammed; Cantrill, Carina; Schuler, Franz; Yu, Li

doi:10.1124/jpet.120.000158

Cited by 6 publications

(4 citation statements)

References 34 publications

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“…The recently described apical efflux ratio (AP-ER) was determined in the P-gp transport assays, and the passive transcellular permeability P app A→B (+I) was included in the evaluation. 43 Respective results are depicted in Table 3 phenol ether 1, which high clearance indicative of fast oxidative metabolism, most likely at the methoxy position. By contrast, medium to high clearance was observed in general on rat microsomes.…”

Section: Results Of the Passive Permeability Microsomal Stability And...mentioning

confidence: 99%

“…In order to rank compounds based on predicted ADME properties suitable for a PET tracer and select the most promising candidates for in vivo pharmacokinetic assessments, Tzs 1 – 4 and 8 – 11 were profiled in three key assays: stability in rodent (Rat) and human (Hu) liver microsomes to predict potential hepatic oxidative clearance (CL) in vivo, PAMPA to assess passive permeability across cell membranes at the BBB, and P-Glycoprotein (P-gp) transport in human (Hu) and rodent (Mo) cell lines to anticipate and minimize potential issues with brain uptake originating from active efflux at the BBB. The recently described apical efflux ratio (AP-ER) was determined in the P-gp transport assays, and the passive transcellular permeability P app A→B (+ I ) was included in the evaluation . Respective results are depicted in Table .…”

Section: Resultsmentioning

confidence: 99%

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Evaluation of Tetrazine Tracers for Pretargeted Imaging within the Central Nervous System

Edelmann,

Bredack,

Belli

et al. 2023

Bioconjugate Chem.

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The pretargeting approach separates the biological half-life of an antibody from the physical half-life of the radioisotope label, providing a strategy for reducing the radiation burden. A widely explored pretargeting approach makes use of the bioorthogonal click reaction between tetrazines (Tzs) and trans-cyclooctenes (TCOs), combining the targeting specificity of monoclonal antibodies (mAbs) with the rapid clearance and precise reaction of Tzs and TCOs. Such a strategy can allow for the targeting and imaging (e.g., by positron emission tomography (PET)) of molecular markers, which cannot be addressed by solely relying on small molecules. Tz derivatives that undergo inverse electron-demand Diels−Alder (IEDDA) reactions with an antibody bearing TCO moieties have been investigated. This study describes the synthesis and characterization of 11 cold Tz imaging agent candidates. These molecules have the potential to be radiolabeled with 18 F or 3 H, and with the former label, they could be of use as imaging tracers for positron emission tomography studies. Selection was made using a multiparameter optimization score for the central nervous system (CNS) PET tracers. Novel tetrazines were tested for their pH-dependent chemical stability. Those which turned out to be stable in a pH range of 6.5−8 were further characterized in in vitro assays with regard to their passive permeability, microsomal stability, and P-glycoprotein transport. Furthermore, selected Tzs were examined for their systemic clearance and CNS penetration in a single-dose pharmacokinetic study in rats. Two tetrazines were successfully labeled with 18 F, one of which showed brain penetration in a biodistribution study in mice. Another Tz was successfully tritium-labeled and used to demonstrate a bioorthogonal click reaction on a TCO-modified antibody. As a result, we identified one Tz as a potential fluorine-18-labeled CNS-PET agent and a second as a 3 H-radioligand for an IEDDA-based reaction with a modified brain-penetrating antibody.

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Section: Results Of the Passive Permeability Microsomal Stability And...mentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Evaluation of Tetrazine Tracers for Pretargeted Imaging within the Central Nervous System

Edelmann,

Bredack,

Belli

et al. 2023

Bioconjugate Chem.

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“…clarifications (25,124,(144)(145)(146)(147)(148)(149). Kalvass et al (133) discussed that the matter comes down to whether CSF represents the brain interstitium for moderate-to-high permeable compounds without major efflux much better than for compounds with extensive efflux.…”

Section: Broad Consensus Around Key Methodological Aspects Of K Puubr...mentioning

confidence: 99%

Unbound Brain-to-Plasma Partition Coefficient, Kp,uu,brain—a Game Changing Parameter for CNS Drug Discovery and Development

et al. 2022

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Purpose More than 15 years have passed since the first description of the unbound brain-to-plasma partition coefficient (Kp,uu,brain) by Prof. Margareta Hammarlund-Udenaes, which was enabled by advancements in experimental methodologies including cerebral microdialysis. Since then, growing knowledge and data continue to support the notion that the unbound (free) concentration of a drug at the site of action, such as the brain, is the driving force for pharmacological responses. Towards this end, Kp,uu,brain is the key parameter to obtain unbound brain concentrations from unbound plasma concentrations. Methods To understand the importance and impact of the Kp,uu,brain concept in contemporary drug discovery and development, a survey has been conducted amongst major pharmaceutical companies based in Europe and the USA. Here, we present the results from this survey which consisted of 47 questions addressing: 1) Background information of the companies, 2) Implementation, 3) Application areas, 4) Methodology, 5) Impact and 6) Future perspectives. Results and conclusions From the responses, it is clear that the majority of the companies (93%) has established a common understanding across disciplines of the concept and utility of Kp,uu,brain as compared to other parameters related to brain exposure. Adoption of the Kp,uu,brain concept has been mainly driven by individual scientists advocating its application in the various companies rather than by a top-down approach. Remarkably, 79% of all responders describe the portfolio impact of Kp,uu,brain implementation in their companies as ‘game-changing’. Although most companies (74%) consider the current toolbox for Kp,uu,brain assessment and its validation satisfactory for drug discovery and early development, areas of improvement and future research to better understand human brain pharmacokinetics/pharmacodynamics translation have been identified.

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“…Noncerebral-originating cells are considered surrogates in blood-CSF barrier modeling. Madin-Darby canine kidney (MDCK and MDCKII) cells, human colonic epithelial cell line Caco-2 cells, Ralph Russ canine kidney cells (RRCK), Lilly Laboratories Culture-Porcine Kidney 1 epithelial cells (LLC-PK1), and cells transfected with specific efflux transporters or pharmacologic targets can be employed as a surrogate cell-based model to assess the permeability of selected compounds in the presence and absence of overexpressed efflux transporters or to evaluate their mechanism of action and effectiveness [159][160][161][162][163][164][165][166]. The spontaneously immortalized MDCK-MDR1 cell line expressing P-gp/ABCB1, MDCK2-ABCB1 cells expressing ABCB1, and LLC-PK1/BCRP cells expressing the efflux transporter ABCG2/BCRP are examples of surrogate cells, which can be used [167].…”

Section: Noncerebral-based Cells (Surrogate Models)mentioning

confidence: 99%

In Vitro Models of the Blood–Cerebrospinal Fluid Barrier and Their Applications in the Development and Research of (Neuro)Pharmaceuticals

2022

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The pharmaceutical research sector has been facing the challenge of neurotherapeutics development and its inherited high-risk and high-failure-rate nature for decades. This hurdle is partly attributable to the presence of brain barriers, considered both as obstacles and opportunities for the entry of drug substances. The blood–cerebrospinal fluid (CSF) barrier (BCSFB), an under-studied brain barrier site compared to the blood–brain barrier (BBB), can be considered a potential therapeutic target to improve the delivery of CNS therapeutics and provide brain protection measures. Therefore, leveraging robust and authentic in vitro models of the BCSFB can diminish the time and effort spent on unproductive or redundant development activities by a preliminary assessment of the desired physiochemical behavior of an agent toward this barrier. To this end, the current review summarizes the efforts and progresses made to this research area with a notable focus on the attribution of these models and applied techniques to the pharmaceutical sector and the development of neuropharmacological therapeutics and diagnostics. A survey of available in vitro models, with their advantages and limitations and cell lines in hand will be provided, followed by highlighting the potential applications of such models in the (neuro)therapeutics discovery and development pipelines.

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Calculation of an Apical Efflux Ratio from P-Glycoprotein (P-gp) In Vitro Transport Experiments Shows an Improved Correlation with In Vivo Cerebrospinal Fluid Measurements in Rats: Impact on P-gp Screening and Compound Optimization

Cited by 6 publications

References 34 publications

Evaluation of Tetrazine Tracers for Pretargeted Imaging within the Central Nervous System

Evaluation of Tetrazine Tracers for Pretargeted Imaging within the Central Nervous System

Unbound Brain-to-Plasma Partition Coefficient, Kp,uu,brain—a Game Changing Parameter for CNS Drug Discovery and Development

In Vitro Models of the Blood–Cerebrospinal Fluid Barrier and Their Applications in the Development and Research of (Neuro)Pharmaceuticals

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