Meeting report of the 5th European Biotransformation Workshop.

1.Challenges, strategies and new technologies in the field of biotransformation were presented and discussed at the 5th European Biotransformation Workshop, which was held on March 14, 2024 on the Novartis Campus in Basel, Switzerland.2. In this meeting report we summarise the presentations and discussions from this workshop.3. The topics covered are listed below:Advances in understanding drug induced liver injury (DILI) risks of carboxylic acids and targeted covalent inhibitorsBiotransformation of oligonucleotide-based therapeutics including automated software tools for metabolite identificationRecent advances in metabolite synthesisQualification and validation of a new compact Low Energy Accelerator Mass Spectrometry (LEA) system for metabolite profiling.

Structural and Physicochemical Features of Oral PROTACs.

Achieving oral bioavailability with Proteolysis Targeting Chimeras (PROTACs) is a key challenge. Here, we report the in vivo pharmacokinetic properties in mouse, rat, and dog of four clinical oral PROTACs and compare with an internally derived data set. We use NMR to determine 3D molecular conformations and structural preorganization free in solution, and we introduce the new experimental descriptors, solvent-exposed H-bond donors (eHBD), and acceptors (eHBA). We derive an upper limit of eHBD ≤ 2 for oral PROTACs in apolar environments and show a greater tolerance for other properties (eHBA, polarity, lipophilicity, and molecular weight) than for Rule-of-5 compliant oral drugs. Within a set of structurally related PROTACs, we show that examples with eHBD > 2 have much lower oral bioavailability than those that have eHBD ≤ 2. We summarize our findings as an experimental "Rule-of-oral-PROTACs" in order to assist medicinal chemists to achieve oral bioavailability in this challenging space.

Meeting report of the 4th European biotransformation workshop.

1. Challenges, strategies and new technologies in the field of biotransformation were presented and discussed at the fourth European Biotransformation Workshop which was held in collaboration with the joint ISSX/DMDG meeting on June 15, 2023 at the University of Hertfordshire in Hatfield, UK.2. In this meeting report we summarise the presentations and discussions from this workshop.3. The topics covered are listed below: Unusual biotransformation reactionsBiotransformation Workflows in Discovery utilising various softwares for structure elucidationBiotransformation software for the identification of peptide metabolitesAccelerator Mass Spectrometry (AMS) for endogenous and xenobiotic metabolite profilingMetabolite profiling using quantitative Nuclear magnetic resonance (NMR) and liquid chromatography coupled to inductively coupled plasma-mass spectrometry (LC-ICP-MS).

Meeting report of the 3rd European Biotransformation Workshop.

Challenges, strategies and new technologies in the field of biotransformation were presented and discussed at the 3rd European Biotransformation Workshop which was held in collaboration with the DMDG on 5-6 October 2022 in Amsterdam. In this meeting report we summarise the presentations and discussions from this workshop. The topics covered are listed below:Accelerator mass spectrometry (AMS) for the support of microtracer studiesBiotransformation of the novel myeloperoxidase inhibitor AZD4831 in preclinical species and humansAMS in biotransformation studies: unusual case studiesDiscussion on new FDA draft guidance and AMSMultimodal molecular imaging and ion mobility applications in drug discovery and developmentMetabolites in Safety Testing considerations for large molecules.

Stereocontrolled Synthesis of Tetrafluoropentanols: Multivicinal Fluorinated Alkane Units for Drug Discovery.

A stereodivergent synthesis of four diastereomeric 2,3,4,5-tetrafluoropentanols is disclosed. X-ray crystallographic analysis reveals conformations that manifest sequential stereoelectronic gauche effects (σC-H/C → σC-F*), thereby generating topological diversity via subtle C(sp3)-H to C(sp3)-F exchange. Two representative tetrafluoro arrays have been incorporated into truncated analogues of Gilenya for the management of relapsing remitting multiple sclerosis. These closely similar multivicinal fluoroalkanes have notably different physicochemical profiles and were found to be stable in the presence of human microsomes.

Exploring physicochemical space via a bioisostere of the trifluoromethyl and ethyl groups (BITE): attenuating lipophilicity in fluorinated analogues of Gilenya® for multiple sclerosis.

The direct, catalytic vicinal difluorination of terminal alkenes via an I(i)/I(iii) manifold was exploited to install a chiral, hybrid bioisostere of the CF3 and Et groups (BITE) in Gilenya®; the first orally available drug for the clinical management of Multiple Sclerosis (MS). This subtle fluorination pattern allows lipophilicity (log D) to be tempered compared to the corresponding CF3 and Et derivatives (CH2CH3 > CH2CF3 > CHFCH2F).

Discovery of a Series of Indole-2 Carboxamides as Selective Secreted Phospholipase A2 Type X (sPLA2-X) Inhibitors.

In order to assess the potential of sPLA2-X as a therapeutic target for atherosclerosis, novel sPLA2 inhibitors with improved type X selectivity are required. To achieve the objective of identifying such compounds, we embarked on a lead generation effort that resulted in the identification of a novel series of indole-2-carboxamides as selective sPLA2-X inhibitors with excellent potential for further optimization.

Design of Selective sPLA2-X Inhibitor (-)-2-{2-[Carbamoyl-6-(trifluoromethoxy)-1H-indol-1-yl]pyridine-2-yl}propanoic Acid.

A lead generation campaign identified indole-based sPLA2-X inhibitors with a promising selectivity profile against other sPLA2 isoforms. Further optimization of sPLA2 selectivity and metabolic stability resulted in the design of (-)-17, a novel, potent, and selective sPLA2-X inhibitor with an exquisite pharmacokinetic profile characterized by high absorption and low clearance, and low toxicological risk. Compound (-)-17 was tested in an ApoE-/- murine model of atherosclerosis to evaluate the effect of reversible, pharmacological sPLA2-X inhibition on atherosclerosis development. Despite being well tolerated and achieving adequate systemic exposure of mechanistic relevance, (-)-17 did not significantly affect circulating lipid and lipoprotein biomarkers and had no effect on coronary function or histological markers of atherosclerosis.

Critical differences in drug metabolic properties of human hepatic cellular models, including primary human hepatocytes, stem cell derived hepatocytes, and hepatoma cell lines.

Primary human hepatocytes (PHH), HepaRG™, HepG2, and two sources of induced pluripotent stem cell (iPSC) derived hepatocytes were characterized regarding gene expression and function of key hepatic proteins, important for the metabolic fate of drugs. The gene expression PCA analysis showed a distance between the two iPSC derived hepatocytes as well as the HepG2 and HepaRG™ cells to the three PHH donors and PHH pool, which were clustered more closely together. Correlation-based hierarchical analysis clustered HepG2 close to the stem cell derived hepatocytes both when the expression of 91 genes related to liver function or only cytochrome P450 (P450) genes were analyzed indicating the non-liver feature and a similar low P450 profile in these cell models. The specific P450 activities and the metabolic pattern of well-characterized drug substances in the cell models demonstrated that iPSC derived hepatocytes had modest levels of CYP3A and CYP2C9, while CYP1A2, 2B6, 2C8, 2C9, 2C19, and 2D6 were barely detectable. High expression of several extrahepatic P450s such as CYP1A1 and 1B1 detected in the stem cell derived hepatocytes may have significant effects on metabolite profiles. However, one of the iPSC derived hepatocytes demonstrated significant combined P450 and conjugating enzyme activity of certain drugs. HepaRG™ cells showed many metabolic properties similar to PHHs and will in many respects be a good model in studies of metabolic pathways and induction of drug metabolism whereas there is still ground to cover before iPSC derived hepatocytes will be seen as a substitute to PHH in drug metabolism studies.

Fluorine-Directed Glycosylation Enables the Stereocontrolled Synthesis of Selective SGLT2 Inhibitors for Type†II Diabetes.

Inhibition of the sodium-glucose co-transporters (SGLT1 and SGLT2) is a validated strategy to address the increasing prevalence of type II diabetes mellitus. However, achieving selective inhibition of human SGLT1 or SGLT2 remains challenging. Orally available small molecule drugs based on the d-glucose core of the natural product Gliflozin have proven to be clinically effective in this regard, effectively impeding glucose reabsorption. Herein, we disclose the influence of molecular editing with fluorine at the C2 position of the pyranose ring of Phlorizin analogues Remogliflozin Etabonate and Dapagliflozin (Farxiga® ) to concurrently direct ß-selective glycosylation, as is required for biological efficacy, and enhance aspects of the physicochemical profile. Given the abundance of glycosylated pharmaceuticals in diabetes therapy that contain a ß-configured d-glucose nucleus, it is envisaged that this strategy may prove to be expansive.

Effects of Tenapanor on Cytochrome P450-Mediated Drug-Drug Interactions.

Tenapanor (RDX5791, AZD1722) is an inhibitor of sodium/hydrogen exchanger isoform 3 in development for the treatment of constipation-predominant irritable bowel syndrome and the treatment of hyperphosphatemia in patients with chronic kidney disease on dialysis. We aimed to investigate whether tenapanor inhibits or induces cytochrome P450s (CYPs). In vitro experiments assessing the potential of tenapanor to affect various CYPs indicated that it could inhibit CYP3A4/5 (IC50 0.4-0.7 µM). An open-label, phase 1 clinical study (NCT02140268) evaluated the pharmacokinetics of the CYP3A4 substrate midazolam when administered with and without tenapanor. Healthy volunteers received a single oral dose of midazolam 7.5 mg on day 1 followed by tenapanor 15 mg twice daily on days 2 to 15, with an additional single 7.5-mg midazolam dose coadministered on day 15. Midazolam exposure was similar whether it was administered alone or with tenapanor (geometric least-squares mean ratio [90%CI] for [midazolam + tenapanor]/midazolam: area under the concentration-time curve, 107% [101% to 113%]; Cmax 104% [89.6% to 122%]). Findings were similar for metabolites of midazolam. These results indicate that tenapanor 15 mg twice daily does not have a clinically relevant impact on CYP3A4 in humans and suggest that tenapanor can be coadministered with CYP3A4-metabolized drugs without affecting their exposure.

Software-aided structural elucidation in drug discovery.

RATIONALE: Structural information on metabolites obtained in relevant biological systems can have considerable impact on the design of new drug candidates. However, with demanding turnaround times, the amount of available structural information may become rate limiting. METHODS: The workflow for metabolite identification used in our laboratory was compared to a workflow using a software tool built for computer-assisted metabolite identification. The present study covered the in vitro metabolism of a diverse set of 65 in-house compounds. The compounds were profiled across three liver-based systems, 17 compounds were tested in human liver microsomes (HLM), 12 in rat hepatocytes (RHEP), and 36 in human hepatocytes (HHEP). RESULTS: For 92% of the metabolites reported, the exact match or Markush representations were in agreement between the two workflows. The major specific biotransformations in hepatocytes which formed the metabolites were aromatic or aliphatic hydroxylations (33%), N-dealkylations (15%) and glucuronidations (12%). CONCLUSIONS: The software was shown to perform well for structural elucidation of metabolites from both phase I and phase II metabolism where the focus was on quickly understanding the rate-limiting metabolic step(s).