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To formalize our understanding ofindiscriminate grafting chemistriesas they pertain to cross-linkable polymers and emerging patterningtechnologies, we designed a new polymer, poly(styrene sulfonyl azide-alt-maleic anhydride) (PSSMA). By modulating its solubility,it can be deposited into smooth, ultrathin films atop polar and nonpolarpolymers. Upon heating above 120 °C or exposure to UV light,highly reactive nitrene intermediates are generated from the azidegroups which form covalent adducts and cross-link the PSSMA. Azidephotolysis and polymer gelation were studied in the context of a statisticalmodel to gain insight into the network outcomes of nitrenes in a polymerfilm. For every azide group converted to a nitrene in ambient atmosphere,it has an 11% likelihood of grafting to another chain and a 5% chanceof causing a scission. These values can be increased over 3-fold byreducing the O2content by 85%. Alternatively, the effectsof quenching by ground-state O2can be mitigated by addingMichler’s ketone (MK) to the film. PSSMA/MK blend films possessa 39% (±13) likelihood for grafting and 29% (±10) for scission.The higher ratio of scission to grafting is a consequence of the sensitizedazides producing triplet-state nitrenes, which favor hydrogen abstraction.These broadly generalizable considerations will be useful to otherswho wish to maximize light sensitivity in related polymer systems. [ABSTRACT FROM AUTHOR]

This Perspective addresses the currentstate of block copolymerlithography and identifies key challenges and opportunities withinthe field. Significant strides in experimental and theoretical thinfilm research have nucleated the transition of block copolymers “fromlab to fab”, but outstanding questions remain about the optimalmaterials, processes, and analytical techniques for first-generationdevices and beyond. Particular attention herein is focused on advancesand issues related to thermal annealing. Block copolymers are poisedto change the traditional lithographic resolution enhancement paradigmfrom “top-down” to “bottom-up”. [ABSTRACT FROM AUTHOR]

Na v 1.7 is an extensively investigated target for pain with a strong genetic link in humans, yet in spite of this effort, it remains challenging to identify efficacious, selective, and safe inhibitors. Here, we disclose the discovery and preclinical profile of GDC-0276 ( 1 ) and GDC-0310 ( 2 ), selective Na v 1.7 inhibitors that have completed Phase 1 trials. Our initial search focused on close-in analogues to early compound 3 . This resulted in the discovery of GDC-0276 ( 1 ), which possessed improved metabolic stability and an acceptable overall pharmacokinetics profile. To further derisk the predicted human pharmacokinetics and enable QD dosing, additional optimization of the scaffold was conducted, resulting in the discovery of a novel series of N-benzyl piperidine Na v 1.7 inhibitors. Improvement of the metabolic stability by blocking the labile benzylic position led to the discovery of GDC-0310 ( 2 ), which possesses improved Na v selectivity and pharmacokinetic profile over 1 .

Understanding the in vivo behavior of experimental therapeutic cells is fundamental to their successful development and clinical translation. Iodine-124 has the longest half-life (4.2 days) among the clinically used positron emitters. Consequently, this isotope offers the longest possible tracking time for directly labeled cells using positron emission tomography (PET). Herein, we have radiosynthesized and evaluated two iodine-124/fluorescein-based dual PET and fluorescent labeling reagents, namely 124 I-FIT-Mal and 124 I-FIT-(PhS) 2 Mal for cell surface thiol bioconjugation. 124 I-FIT-(PhS) 2 Mal labeled cells significantly more effectively than 124 I-FIT-Mal. It conjugated to various cell lines in 22%-62% labeling efficiencies with prolonged iodine-124 retention. 124 I-FIT-(PhS) 2 Mal mainly conjugated on the cell membrane, which was confirmed by high-resolution fluorescence imaging. The migration of 124 I-FIT-(PhS) 2 Mal labeled Jurkat cells was visualized in NSG mice with excellent target-to-background contrast using PET/CT over 7 days. These data demonstrate that 124 I-FIT-(PhS) 2 Mal can dynamically track cell migration in vivo using PET/CT over a clinically relevant time frame.

IRAK4 kinase activity transduces signaling from multiple IL-1Rs and TLRs to regulate cytokines and chemokines implicated in inflammatory diseases. As such, there is high interest in identifying selective IRAK4 inhibitors for the treatment of these disorders. We previously reported the discovery of potent and selective dihydrobenzofuran inhibitors of IRAK4. Subsequent studies, however, showed inconsistent inhibition in disease-relevant pharmacodynamic models. Herein, we describe application of a human whole blood assay to the discovery of a series of benzolactam IRAK4 inhibitors. We identified potent molecule 19 that achieves robust in vivo inhibition of cytokines relevant to human disease., Competing Interests: The authors declare no competing financial interest., (Copyright © 2019 American Chemical Society.)

A series of pyrazolopyrimidine inhibitors of IRAK4 were developed from a high-throughput screen (HTS). Modification of an HTS hit led to a series of bicyclic heterocycles with improved potency and kinase selectivity but lacking sufficient solubility to progress in vivo. Structure-based drug design, informed by cocrystal structures with the protein and small-molecule crystal structures, yielded a series of dihydrobenzofurans. This semisaturated bicycle provided superior druglike properties while maintaining excellent potency and selectivity. Improved physicochemical properties allowed for progression into in vivo experiments, where lead molecules exhibited low clearance and showed target-based inhibition of IRAK4 signaling in an inflammation-mediated PK/PD mouse model.

Using structure- and ligand-based design principles, a novel series of piperidyl chromane arylsulfonamide Na v 1.7 inhibitors was discovered. Early optimization focused on improvement of potency through refinement of the low energy ligand conformation and mitigation of high in vivo clearance. An in vitro hepatotoxicity hazard was identified and resolved through optimization of lipophilicity and lipophilic ligand efficiency to arrive at GNE-616 (24), a highly potent, metabolically stable, subtype selective inhibitor of Na v 1.7. Compound 24 showed a robust PK/PD response in a Na v 1.7-dependent mouse model, and site-directed mutagenesis was used to identify residues critical for the isoform selectivity profile of 24.

The combination of early diagnosis and complete surgical resection offers the greatest prospect of curative cancer treatment. An iodine-124/fluorescein-based dual-modality labeling reagent, 124 I-Green, constitutes a generic tool for one-step installation of a positron emission tomography (PET) and a fluorescent reporter to any cancer-specific antibody. The resulting antibody conjugate would allow both cancer PET imaging and intraoperative fluorescence-guided surgery. 124 I-Green was synthesized in excellent radiochemical yields of 92 ± 5% (n = 4) determined by HPLC with an improved one-pot three-component radioiodination reaction. The A5B7 carcinoembryonic antigen (CEA)-specific antibody was conjugated to 124 I-Green. High tumor uptake of the dual-labeled A5B7 of 20.21 ± 2.70, 13.31 ± 0.73, and 10.64 ± 1.86%ID/g was observed in CEA-expressing SW1222 xenograft mouse model (n = 3) at 24, 48, and 72 h post intravenous injection, respectively. The xenografts were clearly visualized by both PET/CT and ex vivo fluorescence imaging. These encouraging results warrant the further translational development of 124 I-Green for cancer PET imaging and fluorescence-guided surgery.

The epigenetic regulator CBP/P300 presents a novel therapeutic target for oncology. Previously, we disclosed the development of potent and selective CBP bromodomain inhibitors by first identifying pharmacophores that bind the KAc region and then building into the LPF shelf. Herein, we report the "hybridization" of a variety of KAc-binding fragments with a tetrahydroquinoline scaffold that makes optimal interactions with the LPF shelf, imparting enhanced potency and selectivity to the hybridized ligand. To demonstrate the utility of our hybridization approach, two analogues containing unique Asn binders and the optimized tetrahydroquinoline moiety were rapidly optimized to yield single-digit nanomolar inhibitors of CBP with exquisite selectivity over BRD4(1) and the broader bromodomain family.

Inhibition of the bromodomain of the transcriptional regulator CBP/P300 is an especially interesting new therapeutic approach in oncology. We recently disclosed in vivo chemical tool 1 (GNE-272) for the bromodomain of CBP that was moderately potent and selective over BRD4(1). In pursuit of a more potent and selective CBP inhibitor, we used structure-based design. Constraining the aniline of 1 into a tetrahydroquinoline motif maintained potency and increased selectivity 2-fold. Structure-activity relationship studies coupled with further structure-based design targeting the LPF shelf, BC loop, and KAc regions allowed us to significantly increase potency and selectivity, resulting in the identification of non-CNS penetrant 19 (GNE-781, TR-FRET IC 50 = 0.94 nM, BRET IC 50 = 6.2 nM; BRD4(1) IC 50 = 5100 nΜ) that maintained good in vivo PK properties in multiple species. Compound 19 displays antitumor activity in an AML tumor model and was also shown to decrease Foxp3 transcript levels in a dose dependent manner.

The single bromodomain of the closely related transcriptional regulators CBP/EP300 is a target of much recent interest in cancer and immune system regulation. A co-crystal structure of a ligand-efficient screening hit and the CBP bromodomain guided initial design targeting the LPF shelf, ZA loop, and acetylated lysine binding regions. Structure-activity relationship studies allowed us to identify a more potent analogue. Optimization of permeability and microsomal stability and subsequent improvement of mouse hepatocyte stability afforded 59 (GNE-272, TR-FRET IC 50 = 0.02 μM, BRET IC 50 = 0.41 μM, BRD4(1) IC 50 = 13 μM) that retained the best balance of cell potency, selectivity, and in vivo PK. Compound 59 showed a marked antiproliferative effect in hematologic cancer cell lines and modulates MYC expression in vivo that corresponds with antitumor activity in an AML tumor model.

The clinical value of current and future nanomedicines can be improved by introducing patient selection strategies based on noninvasive sensitive whole-body imaging techniques such as positron emission tomography (PET). Thus, a broad method to radiolabel and track preformed nanomedicines such as liposomal drugs with PET radionuclides will have a wide impact in nanomedicine. Here, we introduce a simple and efficient PET radiolabeling method that exploits the metal-chelating properties of certain drugs (e.g., bisphosphonates such as alendronate and anthracyclines such as doxorubicin) and widely used ionophores to achieve excellent radiolabeling yields, purities, and stabilities with 89 Zr, 52 Mn, and 64 Cu, and without the requirement of modification of the nanomedicine components. In a model of metastatic breast cancer, we demonstrate that this technique allows quantification of the biodistribution of a radiolabeled stealth liposomal nanomedicine containing alendronate that shows high uptake in primary tumors and metastatic organs. The versatility, efficiency, simplicity, and GMP compatibility of this method may enable submicrodosing imaging studies of liposomal nanomedicines containing chelating drugs in humans and may have clinical impact by facilitating the introduction of image-guided therapeutic strategies in current and future nanomedicine clinical studies.

Discovery toxicology focuses on the identification of the most promising drug candidates through the development and implementation of lead optimization strategies and hypothesis-driven investigation of issues that enable rational and informed decision-making. The major goals are to [a] identify and progress the drug candidate with the best overall drug safety profile for a therapeutic area, [b] remove the most toxic drugs from the portfolio prior to entry into humans to reduce clinical attrition due to toxicity, and [c] establish a well-characterized hazard and translational risk profile to enable clinical trial designs. This is accomplished through a framework that balances the multiple considerations to identify a drug candidate with the overall best drug characteristics and provides a cogent understanding of mechanisms of toxicity. The framework components include establishing a target candidate profile for each program that defines the qualities of a successful candidate based on the intended therapeutic area, including the risk tolerance for liabilities; evaluating potential liabilities that may result from engaging the therapeutic target (pharmacology-mediated or on-target) and that are chemical structure-mediated (off-target); and characterizing identified liabilities. Lead optimization and investigation relies upon the integrated use of a variety of technologies and models (in silico, in vitro, and in vivo) that have achieved a sufficient level of qualification or validation to provide confidence in their use. We describe the strategic applications of various nonclinical models (established and new) for a holistic and integrated risk assessment that is used for rational decision-making. While this review focuses on strategies for small molecules, the overall concepts, approaches, and technologies are generally applicable to biotherapeutics.