A covalent fragment-based strategy targeting a novel cysteine to inhibit activity of mutant EGFR kinase.

Several generations of ATP-competitive anti-cancer drugs that inhibit the activity of the intracellular kinase domain of the epidermal growth factor receptor (EGFR) have been developed over the past twenty years. The first-generation of drugs such as gefitinib bind reversibly and were followed by a second-generation such as dacomitinib that harbor an acrylamide moiety that forms a covalent bond with C797 in the ATP binding pocket. Resistance emerges through mutation of the T790 gatekeeper residue to methionine, which introduces steric hindrance to drug binding and increases the Km for ATP. A third generation of drugs, such as osimertinib were developed which were effective against T790M EGFR in which an acrylamide moiety forms a covalent bond with C797, although resistance has emerged by mutation to S797. A fragment-based screen to identify new starting points for an EGFR inhibitor serendipitously identified a fragment that reacted with C775, a previously unexploited residue in the ATP binding pocket for a covalent inhibitor to target. A number of acrylamide containing fragments were identified that selectively reacted with C775. One of these acrylamides was optimized to a highly selective inhibitor with sub-1 µM activity, that is active against T790M, C797S mutant EGFR independent of ATP concentration, providing a potential new strategy for pan-EGFR mutant inhibition.

Characterization of sabatolimab, a novel immunotherapy with immuno-myeloid activity directed against TIM-3 receptor.

Objectives: Sabatolimab is a humanized monoclonal antibody (hIgG4, S228P) directed against human T-cell immunoglobulin domain and mucin domain-3 (TIM-3). Herein, we describe the development and characterization of sabatolimab. Methods: Sabatolimab was tested for binding to its target TIM-3 and blocking properties. The functional effects of sabatolimab were tested in T-cell killing and myeloid cell cytokine assays. Antibody-mediated cell phagocytosis (ADCP) by sabatolimab was also assessed. Results: Sabatolimab was shown to (i) enhance T-cell killing and inflammatory cytokine production by dendritic cells (DCs); (ii) facilitate the phagocytic uptake of TIM-3-expressing target cells; and (iii) block the interaction between TIM-3 and its ligands PtdSer/galectin-9. Conclusion: Taken together, our results support both direct anti-leukemic effects and immune-mediated modulation by sabatolimab, reinforcing the notion that sabatolimab represents a novel immunotherapy with immuno-myeloid activity, holding promise for the treatment of myeloid cell neoplasms.

Norepinephrine pressor infusion withdrawal in a National Health Service hospice.

Norepinephrine (NE) is a peripheral vasoconstrictor used as an emergency measure to restore blood pressure secondary to acute hypotension. NE must be administered centrally as a continuous infusion and requires intensive monitoring. Consequently, its use is restricted to critical care environments. We discuss the withdrawal of NE in a hospice for a patient with advanced malignancy and profound hypotension from sepsis. The patient was admitted to intensive care but chose to stop active treatment and insisted on being discharged. Due to concerns about withdrawing NE in the community, he was transferred to a local hospice. We describe various challenges, including the administration and monitoring of NE outside of intensive care, the withdrawal process and concerns that profound hypotension might compromise subcutaneous medications absorption.

Fidgetin-like 2 negatively regulates axonal growth and can be targeted to promote functional nerve regeneration.

The microtubule (MT) cytoskeleton plays a critical role in axon growth and guidance. Here, we identify the MT-severing enzyme fidgetin-like 2 (FL2) as a negative regulator of axon regeneration and a therapeutic target for promoting nerve regeneration after injury. Genetic knockout of FL2 in cultured adult dorsal root ganglion neurons resulted in longer axons and attenuated growth cone retraction in response to inhibitory molecules. Given the axonal growth-promoting effects of FL2 depletion in vitro, we tested whether FL2 could be targeted to promote regeneration in a rodent model of cavernous nerve (CN) injury. The CNs are parasympathetic nerves that regulate blood flow to the penis, which are commonly damaged during radical prostatectomy (RP), resulting in erectile dysfunction (ED). Application of FL2-siRNA after CN injury significantly enhanced functional nerve recovery. Remarkably, following bilateral nerve transection, visible and functional nerve regeneration was observed in 7 out of 8 animals treated with FL2-siRNA, while no control-treated animals exhibited regeneration. These studies identify FL2 as a promising therapeutic target for enhancing regeneration after peripheral nerve injury and for mitigating neurogenic ED after RP - a condition for which, at present, only poor treatment options exist.

Application of Off-Rate Screening in the Identification of Novel Pan-Isoform Inhibitors of Pyruvate Dehydrogenase Kinase.

Libraries of nonpurified resorcinol amide derivatives were screened by surface plasmon resonance (SPR) to determine the binding dissociation constant (off-rate, kd) for compounds binding to the pyruvate dehydrogenase kinase (PDHK) enzyme. Parallel off-rate measurements against HSP90 and application of structure-based drug design enabled rapid hit to lead progression in a program to identify pan-isoform ATP-competitive inhibitors of PDHK. Lead optimization identified selective sub-100-nM inhibitors of the enzyme which significantly reduced phosphorylation of the E1α subunit in the PC3 cancer cell line in vitro.

Dynamic undocking and the quasi-bound state as tools for drug discovery.

There is a pressing need for new technologies that improve the efficacy and efficiency of drug discovery. Structure-based methods have contributed towards this goal but they focus on predicting the binding affinity of protein-ligand complexes, which is notoriously difficult. We adopt an alternative approach that evaluates structural, rather than thermodynamic, stability. As bioactive molecules present a static binding mode, we devised dynamic undocking (DUck), a fast computational method to calculate the work necessary to reach a quasi-bound state at which the ligand has just broken the most important native contact with the receptor. This non-equilibrium property is surprisingly effective in virtual screening because true ligands form more-resilient interactions than decoys. Notably, DUck is orthogonal to docking and other 'thermodynamic' methods. We demonstrate the potential of the docking-undocking combination in a fragment screening against the molecular chaperone and oncology target Hsp90, for which we obtain novel chemotypes and a hit rate that approaches 40%.

'I don't think I'd be frightened if the statins went': a phenomenological qualitative study exploring medicines use in palliative care patients, carers and healthcare professionals.

BACKGROUND: There is a growing body of evidence suggesting patients with life-limiting illness use medicines inappropriately and unnecessarily. In this context, the perspective of patients, their carers and the healthcare professionals responsible for prescribing and monitoring their medication is important for developing deprescribing strategies. The aim of this study was to explore the lived experience of patients, carers and healthcare professionals in the context of medication use in life-limiting illness. METHODS: In-depth interviews, using a phenomenological approach: methods of transcendental phenomenology were used for the patient and carer interviews, while hermeneutic phenomenology was used for the healthcare professional interviews. RESULTS: The study highlighted that medication formed a significant part of a patient's day-to-day routine; this was also apparent for their carers who took on an active role-as a gatekeeper of care-in managing medication. Patients described the experience of a point in which, in their disease journey, they placed less importance on taking certain medications; healthcare professionals also recognize this and refer it as a 'transition'. This point appeared to occur when the patient became accepting of their illness and associated life expectancy. There was also willingness by patients, carers and healthcare professionals to review and alter the medication used by patients in the context of life-limiting illness. CONCLUSIONS: There is a need to develop deprescribing strategies for patients with life-limiting illness. Such strategies should seek to establish patient expectations, consider the timing of the discussion about ceasing treatment and encourage the involvement of other stakeholders in the decision-making progress.

Identification of novel, in vivo active Chk1 inhibitors utilizing structure guided drug design.

Chk1 kinase is a critical component of the DNA damage response checkpoint especially in cancer cells and targeting Chk1 is a potential therapeutic opportunity for potentiating the anti-tumor activity of DNA damaging chemotherapy drugs. Fragment elaboration by structure guided design was utilized to identify and develop a novel series of Chk1 inhibitors culminating in the identification of V158411, a potent ATP-competitive inhibitor of the Chk1 and Chk2 kinases. V158411 abrogated gemcitabine and camptothecin induced cell cycle checkpoints, resulting in the expected modulation of cell cycle proteins and increased cell death in cancer cells. V158411 potentiated the cytotoxicity of gemcitabine, cisplatin, SN38 and camptothecin in a variety of p53 deficient human tumor cell lines in vitro, p53 proficient cells were unaffected. In nude mice, V158411 showed minimal toxicity as a single agent and in combination with irinotecan. In tumor bearing animals, V158411 was detected at high levels in the tumor with a long elimination half-life; no pharmacologically significant in vivo drug-drug interactions with irinotecan were identified through analysis of the pharmacokinetic profiles. V158411 potentiated the anti-tumor activity of irinotecan in a variety of human colon tumor xenograft models without additional systemic toxicity. These results demonstrate the opportunity for combining V158411 with standard of care chemotherapeutic agents to potentiate the therapeutic efficacy of these agents without increasing their toxicity to normal cells. Thus, V158411 would warrant further clinical evaluation.

Dopaminergic mediation of the discriminative stimulus functions of modafinil in rats.

RATIONALE: Modafinil is a wake-promoting drug with FDA approval for the treatment of excessive daytime sleepiness that has been prescribed for ADHD and recently assessed as a potential treatment for psychostimulant dependence. Previous research indicates that modafinil modestly increases locomotor activity and produces similar discriminative stimulus effects to psychostimulants in rodents, although the subjective effects of modafinil are reportedly distinct from those of cocaine or amphetamine in humans with a history of psychostimulant abuse. OBJECTIVES: The current study employed drug discrimination procedures in rats to examine the pharmacological actions contributing to modafinil's discriminative stimulus functions. METHODS: Eight male Sprague-Dawley rats were trained to discriminate intragastric administration of 256 mg/kg modafinil from vehicle (5% arabic gum) under a FR 20 schedule of food reinforcement. Substitution tests were conducted with various dopaminergic agents (d-amphetamine, cocaine, PNU-91356A, GBR 12909, methylphenidate) and nondopaminergic agents (nicotine, ethanol). Antagonist tests were conducted with the selective D1 antagonist, SCH 39166, and the nonselective D2 antagonist, haloperidol. RESULTS: Rats trained to discriminate modafinil displayed complete stimulus generalization to cocaine, methylphenidate, and GBR 12909 and the discrimination was completely blocked by both SCH 39166 and haloperidol. Evidence for significant partial substitution was obtained with d-amphetamine, PNU-91356A, and nicotine. CONCLUSIONS: Results strongly support the role of dopaminergic mechanisms in the discriminative stimulus functions of modafinil, although further evaluation regarding the contribution of other neurotransmitter systems to these effects should be continued. The findings are discussed in light of clinical research efforts with modafinil as a treatment for psychostimulant dependence.

VER-246608, a novel pan-isoform ATP competitive inhibitor of pyruvate dehydrogenase kinase, disrupts Warburg metabolism and induces context-dependent cytostasis in cancer cells.

Pyruvate dehydrogenase kinase (PDK) is a pivotal enzyme in cellular energy metabolism that has previously been implicated in cancer through both RNAi based studies and clinical correlations with poor prognosis in several cancer types. Here, we report the discovery of a novel and selective ATP competitive pan-isoform inhibitor of PDK, VER-246608. Consistent with a PDK mediated MOA, VER-246608 increased pyruvate dehydrogenase complex (PDC) activity, oxygen consumption and attenuated glycolytic activity. However, these effects were only observed under D-glucose-depleted conditions and required almost complete ablation of PDC E1α subunit phosphorylation. VER-246608 was weakly anti-proliferative to cancer cells in standard culture media; however, depletion of either serum or combined D-glucose/L-glutamine resulted in enhanced cellular potency. Furthermore, this condition-selective cytostatic effect correlated with reduced intracellular pyruvate levels and an attenuated compensatory response involving deamination of L-alanine. In addition, VER-246608 was found to potentiate the activity of doxorubicin. In contrast, the lipoamide site inhibitor, Nov3r, demonstrated sub-maximal inhibition of PDK activity and no evidence of cellular activity. These studies suggest that PDK inhibition may be effective under the nutrient-depleted conditions found in the tumour microenvironment and that combination treatments should be explored to reveal the full potential of this therapeutic strategy.

Inhibition of fast axonal transport by pathogenic SOD1 involves activation of p38 MAP kinase.

Dying-back degeneration of motor neuron axons represents an established feature of familial amyotrophic lateral sclerosis (FALS) associated with superoxide dismutase 1 (SOD1) mutations, but axon-autonomous effects of pathogenic SOD1 remained undefined. Characteristics of motor neurons affected in FALS include abnormal kinase activation, aberrant neurofilament phosphorylation, and fast axonal transport (FAT) deficits, but functional relationships among these pathogenic events were unclear. Experiments in isolated squid axoplasm reveal that FALS-related SOD1 mutant polypeptides inhibit FAT through a mechanism involving a p38 mitogen activated protein kinase pathway. Mutant SOD1 activated neuronal p38 in mouse spinal cord, neuroblastoma cells and squid axoplasm. Active p38 MAP kinase phosphorylated kinesin-1, and this phosphorylation event inhibited kinesin-1. Finally, vesicle motility assays revealed previously unrecognized, isoform-specific effects of p38 on FAT. Axon-autonomous activation of the p38 pathway represents a novel gain of toxic function for FALS-linked SOD1 proteins consistent with the dying-back pattern of neurodegeneration characteristic of ALS.

Phase II evaluation of phenoxodiol in combination with cisplatin or paclitaxel in women with platinum/taxane-refractory/resistant epithelial ovarian, fallopian tube, or primary peritoneal cancers.

INTRODUCTION: Chemoresistance is a major limitation in the treatment of ovarian cancer. Phenoxodiol is a novel biomodulator capable of reversing chemoresistance in vitro and in vivo. In this study, we determined the safety and efficacy of intravenous phenoxodiol in combination with cisplatin or paclitaxel in women with platinum/taxane-refractory/resistant ovarian cancers. METHODS: Thirty-two patients were randomized to 1 of 2 treatment arms according to their previous responses: (1) platinum refractory/resistant, cisplatin (40 mg/m intravenous) weekly on day 2 + phenoxodiol (3 mg/kg) weekly on days 1 and 2 and (2) taxane refractory/resistant, paclitaxel (80 mg/m IV) weekly on day 2 and phenoxodiol (3 mg/kg) weekly on days 1 and 2. Patients continued on treatment until complete response, disease progression, unacceptable toxicity, or voluntary withdrawal. RESULTS: There were no treatment-related deaths. There was only one treatment-related hospitalization and 2 grade 4 toxicities. In the cisplatin arm, there were 3 partial responses, 9 patients (56%) achieved stable disease, 4 (25%) progressed, and the overall best response rate was 19%. In the paclitaxel arm, there was one complete response and 2 partial responses, 8 patients (53%) achieved stable disease, 4 patients (27%) progressed, and the overall best response rate was 20%. DISCUSSION: The combination of IV phenoxodiol with cisplatin or paclitaxel was well tolerated in this study. Cisplatin-phenoxodiol was particularly active and warrants further study in patients with platinum-resistant ovarian cancer.

In vivo electroporation enhances the potency of poly-lactide co-glycolide (PLG) plasmid DNA immunization.

Immunization with plasmid DNA that has been encapsulated in poly lactide-co-glycolide (PLG) microparticles targets the plasmid DNA to antigen presenting cells and elicits immune responses to the encoded antigen(s). Application of a series of electrical pulses (EPT) immediately following unformulated DNA injection enhances expression of the encoded antigen and increases immune responses. The combination of using EPT before or after PLG-encapsulated plasmid DNA immunization was tested to determine if enhanced immune responses would be generated. The results show that the combination lead to both enhanced expression of antigen and more robust T cell responses, even if EPT was applied prior to immunization. The data also demonstrate that recruitment of phagocytes to the injection site was markedly enhanced by EPT, and this resulted in an increase of the antigen expression levels in these cells. Co-administration of microparticles and EPT also effected localized necrosis of muscle fibers, caused persistent Th-1-modulated cytokine production, and lead to the release of two endogenous adjuvants, uric acid and HMGB1. In all, we describe that increased immunogenicity observed with the combination of PLG-encapsulated plasmid DNA microparticle with EPT was caused by an increase in the recruitment of antigen presenting cells which mediated a more robust T cell response than observed with immunization alone.

Discovery of cell-active phenyl-imidazole Pin1 inhibitors by structure-guided fragment evolution.

Pin1 is an emerging oncology target strongly implicated in Ras and ErbB2-mediated tumourigenesis. Pin1 isomerizes bonds linking phospho-serine/threonine moieties to proline enabling it to play a key role in proline-directed kinase signalling. Here we report a novel series of Pin1 inhibitors based on a phenyl imidazole acid core that contains sub-µM inhibitors. Compounds have been identified that block prostate cancer cell growth under conditions where Pin1 is essential.

Structure-guided design of alpha-amino acid-derived Pin1 inhibitors.

The peptidyl prolyl cis/trans isomerase Pin1 is a promising molecular target for anti-cancer therapeutics. Here we report the structure-guided evolution of an indole 2-carboxylic acid fragment hit into a series of alpha-benzimidazolyl-substituted amino acids. Examples inhibited Pin1 activity with IC(50) <100nM, but were inactive on cells. Replacement of the benzimidazole ring with a naphthyl group resulted in a 10-50-fold loss in ligand potency, but these examples downregulated biomarkers of Pin1 activity and blocked proliferation of PC3 cells.

Targeted transgene integration in plant cells using designed zinc finger nucleases.

Targeted transgene integration in plants remains a significant technical challenge for both basic and applied research. Here it is reported that designed zinc finger nucleases (ZFNs) can drive site-directed DNA integration into transgenic and native gene loci. A dimer of designed 4-finger ZFNs enabled intra-chromosomal reconstitution of a disabled gfp reporter gene and site-specific transgene integration into chromosomal reporter loci following co-transformation of tobacco cell cultures with a donor construct comprised of sequences necessary to complement a non-functional pat herbicide resistance gene. In addition, a yeast-based assay was used to identify ZFNs capable of cleaving a native endochitinase gene. Agrobacterium delivery of a Ti plasmid harboring both the ZFNs and a donor DNA construct comprising a pat herbicide resistance gene cassette flanked by short stretches of homology to the endochitinase locus yielded up to 10% targeted, homology-directed transgene integration precisely into the ZFN cleavage site. Given that ZFNs can be designed to recognize a wide range of target sequences, these data point toward a novel approach for targeted gene addition, replacement and trait stacking in plants.

Screening for postpartum depression in a rural community.

Postpartum depression is a serious mental health issue affecting as many as 10-15% of families during the postpartum period. The current study discusses implementation of a screening protocol for postpartum depression in a rural community health setting with a sample of 498 primarily minority women utilizing the Postpartum Depression Screening Scale. Results indicate that 22.5% of the sample population demonstrate some symptoms of postpartum depression, with Hispanic women demonstrating less symptoms than other minority groups. Results also indicate that variables such as race, feeding method and history of depression impact scale scores.

Cervical intrathecal analgesia for head and neck/upper limb cancer pain: six case reports.

We describe six cases of head and neck or upper limb cancer palliative care patients with refractory pain, treated with an intrathecal catheter placed at cervical or upper thoracic spinal levels with a non-implanted, externalized and tunnelled delivery system. In these cases, this system was safe and effective.