Industry Perspective on the Pharmacokinetic and Absorption, Distribution, Metabolism, and Excretion Characterization of Heterobifunctional Protein Degraders.

Targeted protein degraders (TPDs), specifically the bifunctional protein degraders discussed in this manuscript, consist of two linked ligands for a protein of interest and an E3 ligase, resulting in molecules that largely violate accepted physicochemical limits (e.g., Lipinski's Rule of Five) for oral bioavailability. In 2021, the IQ Consortium Degrader DMPK/ADME Working Group undertook a survey of 18 IQ member and nonmember companies working on degraders to understand whether the characterization and optimization of these molecules were different from any other beyond the Rule of Five (bRo5) compounds. Additionally, the working group sought to identify pharmacokinetic (PK)/absorption, distribution, metabolism, and excretion (ADME) areas in need of further evaluation and where additional tools could aid in more rapid advancement of TPDs to patients. The survey revealed that although TPDs reside in a challenging bRo5 physicochemical space, most respondents focus their efforts on oral delivery. Physicochemical properties required for oral bioavailability were generally consistent across the companies surveyed. Many of the member companies used modified assays to address challenging degrader properties (e.g., solubility, nonspecific binding), but only half indicated that they modified their drug discovery workflows. The survey also suggested the need for further scientific investigation in the areas of central nervous system penetration, active transport, renal elimination, lymphatic absorption, in silico/machine learning, and human pharmacokinetic prediction. Based on the survey results, the Degrader DMPK/ADME Working Group concluded that TPD evaluation does not fundamentally differ from other bRo5 compounds but requires some modification compared with traditional small molecules and proposes a generic workflow for PK/ADME evaluation of bifunctional TPDs. SIGNIFICANCE STATEMENT: Based on an industry survey, this article provides an understanding of the current state of absorption, distribution, metabolism, and excretion science pertaining to characterizing and optimizing targeted protein degraders, specifically bifunctional protein degraders, based upon responses by 18 IQ consortium members and non-members developing targeted protein degraders. Additionally, this article puts into context the differences / similarities in methods and strategies utilized for heterobifunctional protein degraders compared to other beyond Rule of Five molecules and conventional small molecule drugs.

Chemical, Analytical and Pharmacokinetic Characterisation of RO7304898, an API Consisting of Two Rapidly Interconverting Diastereoisomers.

PURPOSE: Exploration of the chemical, analytical and pharmacokinetic properties of the API, RO7304898, an allosteric EGFR inhibitor, intended to be developed as a mixture of two rapidly interconverting diastereoisomers with composition ratio of approximately 1:1. METHODS: Assessment of diastereoisomer stereochemistry, interconversion rates, binding to EGFR protein, metabolic stability and in vivo PK in Wistar-Han rats was conducted. RESULTS: The two diastereoisomers of the API undergo fast interconversion at physiologically relevant pH and direct EGFR binding studies revealed diastereoisomer B to be the active moiety. Pharmacokinetic studies in rat revealed a low-moderate total plasma clearance of the API along with similar plasma concentration-time profiles for diastereoisomers A and B, and the diastereoisomeric ratio reached stable equilibrium favoring formation of the potent diastereoisomer B. In in vitro incubations, the API was metabolically stable in plasma and hepatocyte suspension incubations in all species tested except that of rat hepatocytes. Additionally, only small species differences in the A:B composition were observed in vitro with the potent diastereoisomer B being the predominant form. CONCLUSIONS: We demonstrated that the API, a mixture of two diastereoisomers; A (impotent) and B (potent), undergoes rapid interconversion which is faster than the apparent distribution and elimination rates of the individual diastereoisomers in vivo in rat, serving to diminish concerns that separate diastereoisomer effects may occur in subsequent pharmacologic and pivotal toxicological studies. Whilst vigilant monitoring of the diastereoisomeric ratio will need to be continued, this data adds confidence on the development pathway for this API to the clinic.

A translational strategy employing physiologically based modelling to predict the pharmacological active dose of RO7119929, an oral prodrug of a targeted cancer immunotherapy TLR7 agonist.

RO7119929 is being developed as an orally administered prodrug of the TLR7-specific agonist and active drug, RO7117418, for the treatment of patients with solid tumours.In this publication, we present a case study wherein the human pharmacokinetics and pharmacological active dose were prospectively predicted following oral administration of the prodrug.A simple translational pharmacokinetic-pharmacodynamic strategy was applied to predict the pharmacological active dose of the prodrug in human. In vivo studies in monkey showed that an unbound plasma exposure of active drug of 1.5 ng/mL elicited secretion of key serum pharmacodynamic cytokine and chemokine biomarkers in monkey. This threshold of 1.5 ng/mL was close to the minimum effective concentration of active drug required to induce cytokine secretion in human peripheral blood mononuclear cells (3 ng/mL).Measured in vitro physicochemical and biochemical properties of the prodrug and active drug were applied as input parameters in physiologically based pharmacokinetic models to predict the pharmacokinetics of active drug after oral dosing of the prodrug in humans. Then, using the PBPK model, a dose which delivered an unbound plasma Cmax in line with the target pharmacodynamic threshold of 1.5 ng/mL was found. This defined the lowest pharmacologically active dose as 3 mg.The prodrug entered the clinic in 2020 in patients with primary or secondary liver cancers. Clear pharmacodynamic, transient, and dose-dependent cytokine induction was observed at prodrug doses > 1 mg.

In vitro and in vivo characterization of a novel, highly potent p53-MDM2 inhibitor.

Small molecule inhibitors of the p53-MDM2 protein complex are under intense investigation in clinical trials as anti-cancer agents, including our first generation inhibitor NVP-CGM097. We recently described the rational design of a novel pyrazolopyrrolidinone core as a new lead structure and now we report on the synthesis and optimization of this to provide a highly potent lead compound. This new compound displayed excellent oral efficacy in our preclinical mechanistic in vivo model and marked a significant milestone towards the identification of our second generation clinical candidate NVP-HDM201.

Design and Synthesis of Inhibitors of the E3 Ligase SMAD Specific E3 Ubiquitin Protein Ligase 1 as a Treatment for Lung Remodeling in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a devastating rare disease, which despite currently available treatments, still represents a high unmet medical need. Specific E3 ubiquitin protein ligase 1 (SMURF1) is a HECT E3 ligase that ubiquitinates key signaling molecules from the TGFß/BMP pathways, which are of great relevance in the pathophysiology of PAH. Herein, the design and synthesis of novel potent small-molecule SMURF1 ligase inhibitors are described. Lead molecule 38 has demonstrated good oral pharmacokinetics in rats and significant efficacy in a rodent model of pulmonary hypertension.

Translating pharmacology models effectively to predict therapeutic benefit.

Many in vitro and in vivo models are used in pharmacological research to evaluate the role of targeted proteins in a disease. Understanding the translational relevance and limitation of these models for analyzing a drug's disposition, pharmacokinetic/pharmacodynamic (PK/PD) profile, mechanism, and efficacy, is essential when selecting the most appropriate model of the disease of interest and predicting clinically efficacious doses of the investigational drug. Selected animal models used in ophthalmology, infectious diseases, oncology, autoimmune diseases, and neuroscience are reviewed here. Each area has specific challenges around translatability and determination of an efficacious dose: new patient-specific dosing methods may help overcome these limitations.

Preclinical Characterization of a Next-Generation Brain Permeable, Paradox Breaker BRAF Inhibitor.

PURPOSE: Disease progression in BRAF V600E/K positive melanomas to approved BRAF/MEK inhibitor therapies is associated with the development of resistance mediated by RAF dimer inducing mechanisms. Moreover, progressing disease after BRAFi/MEKi frequently involves brain metastasis. Here we present the development of a novel BRAF inhibitor (Compound Ia) designed to address the limitations of available BRAFi/MEKi. EXPERIMENTAL DESIGN: The novel, brain penetrant, paradox breaker BRAFi is comprehensively characterized in vitro, ex vivo, and in several preclinical in vivo models of melanoma mimicking peripheral disease, brain metastatic disease, and acquired resistance to first-generation BRAFi. RESULTS: Compound Ia manifested elevated potency and selectivity, which triggered cytotoxic activity restricted to BRAF-mutated models and did not induce RAF paradoxical activation. In comparison to approved BRAFi at clinical relevant doses, this novel agent showed a substantially improved activity in a number of diverse BRAF V600E models. In addition, as a single agent, it outperformed a currently approved BRAFi/MEKi combination in a model of acquired resistance to clinically available BRAFi. Compound Ia presents high central nervous system (CNS) penetration and triggered evident superiority over approved BRAFi in a macro-metastatic and in a disseminated micro-metastatic brain model. Potent inhibition of MAPK by Compound Ia was also demonstrated in patient-derived tumor samples. CONCLUSIONS: The novel BRAFi demonstrates preclinically the potential to outperform available targeted therapies for the treatment of BRAF-mutant tumors, thus supporting its clinical investigation.

Discovery of Novel Allosteric EGFR L858R Inhibitors for the Treatment of Non-Small-Cell Lung Cancer as a Single Agent or in Combination with Osimertinib.

Addressing resistance to third-generation EGFR TKIs such as osimertinib via the EGFRC797S mutation remains a highly unmet need in EGFR-driven non-small-cell lung cancer (NSCLC). Herein, we present the discovery of the allosteric EGFR inhibitor 57, a novel fourth-generation inhibitor to overcome EGFRC797S-mediated resistance in patients harboring the activating EGFRL858R mutation. 57 exhibits an improved potency compared to previous allosteric EGFR inhibitors. To our knowledge, 57 is the first allosteric EGFR inhibitor that demonstrates robust tumor regression in a mutant EGFRL858R/C797S tumor model. Additionally, 57 is active in an H1975 EGFRL858R/T790M NSCLC xenograft model and shows superior efficacy in combination with osimertinib compared to the single agents. Our data highlight the potential of 57 as a single agent against EGFRL858R/C797S and EGFRL858R/T790M/C797S and as combination therapy for EGFRL858R- and EGFRL858R/T790M-driven NSCLC.

Fundamental aspects of DMPK optimization of targeted protein degraders.

Targeted protein degraders are an emerging modality. Their properties fall outside the traditional small-molecule property space and are in the 'beyond rule of 5' space. Consequently, drug discovery programs focused on developing orally bioavailable degraders are expected to face complex drug metabolism and pharmacokinetics (DMPK) challenges compared with traditional small molecules. Nevertheless, little information is available on the DMPK optimization of oral degraders. Therefore, in this review, we discuss our experience of these DMPK optimization challenges and present methodologies and strategies to overcome the hurdles dealing with this new small-molecule modality, specifically in developing oral degraders to treat cancer.

Identification of cryptolepine metabolites in rat and human hepatocytes and metabolism and pharmacokinetics of cryptolepine in Sprague Dawley rats.

BACKGROUND: This study aims at characterizing the in vitro metabolism of cryptolepine using human and rat hepatocytes, identifying metabolites in rat plasma and urine after a single cryptolepine dose, and evaluating the single-dose oral and intravenous pharmacokinetics of cryptolepine in male Sprague Dawley (SD) rats. METHODS: The in vitro metabolic profiles of cryptolepine were determined by LC-MS/MS following incubation with rat and human hepatocytes. The in vivo metabolic profile of cryptolepine was determined in plasma and urine samples from Sprague Dawley rats following single-dose oral administration of cryptolepine. Pharmacokinetic parameters of cryptolepine were determined in plasma and urine from Sprague Dawley rats after single-dose intravenous and oral administration. RESULTS: Nine metabolites were identified in human and rat hepatocytes, resulting from metabolic pathways involving oxidation (M2-M9) and glucuronidation (M1, M2, M4, M8, M9). All human metabolites were found in rat hepatocyte incubations except glucuronide M1. Several metabolites (M2, M6, M9) were also identified in the urine and plasma of rats following oral administration of cryptolepine. Unchanged cryptolepine detected in urine was negligible. The Pharmacokinetic profile of cryptolepine showed a very high plasma clearance and volume of distribution (Vss) resulting in a moderate average plasma half-life of 4.5 h. Oral absorption was fast and plasma exposure and oral bioavailability were low. CONCLUSIONS: Cryptolepine metabolism is similar in rat and human in vitro with the exception of direct glucuronidation in human. Clearance in rat and human is likely to include a significant metabolic contribution, with proposed primary human metabolism pathways hydroxylation, dihydrodiol formation and glucuronidation. Cryptolepine showed extensive distribution with a moderate half-life.

Discovery of a Dihydroisoquinolinone Derivative (NVP-CGM097): A Highly Potent and Selective MDM2 Inhibitor Undergoing Phase 1 Clinical Trials in p53wt Tumors.

As a result of our efforts to discover novel p53:MDM2 protein-protein interaction inhibitors useful for treating cancer, the potent and selective MDM2 inhibitor NVP-CGM097 (1) with an excellent in vivo profile was selected as a clinical candidate and is currently in phase 1 clinical development. This article provides an overview of the discovery of this new clinical p53:MDM2 inhibitor. The following aspects are addressed: mechanism of action, scientific rationale, binding mode, medicinal chemistry, pharmacokinetic and pharmacodynamic properties, and in vivo pharmacology/toxicology in preclinical species.

A distinct p53 target gene set predicts for response to the selective p53-HDM2 inhibitor NVP-CGM097.

Biomarkers for patient selection are essential for the successful and rapid development of emerging targeted anti-cancer therapeutics. In this study, we report the discovery of a novel patient selection strategy for the p53-HDM2 inhibitor NVP-CGM097, currently under evaluation in clinical trials. By intersecting high-throughput cell line sensitivity data with genomic data, we have identified a gene expression signature consisting of 13 up-regulated genes that predicts for sensitivity to NVP-CGM097 in both cell lines and in patient-derived tumor xenograft models. Interestingly, these 13 genes are known p53 downstream target genes, suggesting that the identified gene signature reflects the presence of at least a partially activated p53 pathway in NVP-CGM097-sensitive tumors. Together, our findings provide evidence for the use of this newly identified predictive gene signature to refine the selection of patients with wild-type p53 tumors and increase the likelihood of response to treatment with p53-HDM2 inhibitors, such as NVP-CGM097.

In vitro assessment of colistin's antipseudomonal antimicrobial interactions with other antibiotics.

OBJECTIVE: To study the interactions of colistin (MIC 2 mg/L) at concentrations of 0.5 and 5 mg/L with ceftazidime (1 and 75 mg/L, MIC 0.5 mg/L), aztreonam (1 and 30 mg/L, MIC 0.12 mg/L), meropenem (1 and 25 mg/L, MIC 0.03 mg/L), gentamicin (1 and 10 mg/L, MIC 2 mg/L), piperacillin (5 and 100 mg/L, MIC 4 mg/L) and ciprofloxacin (0.25 and 4 mg/L, MIC 1 mg/L) using a representative strain of Pseudomonas aeruginosa isolated from a cystic fibrosis patient. METHODS: The method used was a bacterial time kill curve with single agents and combinations. Using inocula of 106 CFU/mL, multiple sampling was performed over 6 h and in triplicate. The AUBKC of the time versus viable count curve, with single agents and combinations of agents, was taken as the endpoint for comparison. RESULTS: For colistin plus ceftazidime, colistin plus aztreonam, colistin plus meropenem and colistin plus ciprofloxacin, the pattern was for all the combinations (high or low concentrations) to produce smaller AUBKCs than single agents. In experiments using a bacteriostatic agent such as ceftazidime, the AUBKCs (log CFU/µL per h) for colistin 0.5 mg/L or 5 mg/L alone were 32.3±0.8 or 12.7±0.5, and for ceftazidime 1 mg/L or 75 mg/L alone they were 24.3±1.5 or 20.9±2.7. Combinations of colistin 0.5 mg/L plus either ceftazidime 1 mg/L or 75 mg/L produced AUBKCs of 23.8±1.8 or 16.1 mg/L. Combinations of colistin 5 mg/L plus ceftazidime 1 mg/L or 75 mg/L produced AUBKCs of 12.2±0.8 or 8.7±1.0. The AUBKCs for colistin 5 mg/L plus 75 mg/L are significantly smaller than those for the single agents, indicating synergy. In experiments using the bactericidal agent ciprofloxacin, the AUBKCs (log CFU/mL per h) for colistin 0.5 mg/L or 5 mg/L alone were 33.6±1.9 or 11.2±2.4, and for ciprofloxacin 0.25 mg/L or 4 mg/L alone they were 32.8±1.3 or 5.0±0.7. Combinations of colistin 0.5 mg/L plus either ciprofloxacin 0.25 mg/L or 4 mg/L produced AUBKCs of 32.2±0.9 or 4.3±1.4. Combinations of colistin 5 mg/L plus ciprofloxacin 0.25 mg/L or 4 mg/L produced AUBKCs of 10.7±1.5 or 4.2±0.6. Although combination AUBKCs were smaller than those for single agents, in no case did this reach statistical significance (p<0.05). CONCLUSIONS: These studies indicate that addition of colistin to other antipseudomonal drugs tends to produce smaller AUBKCs and hence greater killing of Pseudomonas aeruginosa than monotherapy.