A Degron Blocking Strategy Towards Improved CRL4CRBN Recruiting PROTAC Selectivity

Small molecules inducing protein degradation are important pharmacological tools to interrogate complex biology and are rapidly translating into clinical agents. However, to fully realise the potential of these molecules, selectivity remains a limiting challenge. Herein, we addressed the issue of selectivity in the design of CRL4CRBN recruiting PROteolysis TArgeting Chimeras (PROTACs). Thalidomide derivatives used to generate CRL4CRBN recruiting PROTACs have well described intrinsic monovalent degradation profiles by inducing the recruitment of neo-substrates, such as GSPT1, Ikaros and Aiolos. We leveraged structural insights from known CRL4CRBN neo-substrates to attenuate and indeed remove this monovalent degradation function in well-known CRL4CRBN molecular glues degraders, namely CC-885 and Pomalidomide. We then applied these design principles on a previously published BRD9 PROTAC (dBRD9-A) and generated an analogue with improved selectivity profile. Finally, we implemented a computational modelling pipeline to show that our degron blocking design does not impact PROTAC-induced ternary complex formation. We believe that the tools and principles presented in this work will be valuable to support the development of targeted protein degradation.

1366 DEVELOPING A PHARMACIST DELIVERED MEDICINES REVIEW TOOL FOR PATIENTS WITH FRAILTY, ENHANCING CGA

Background

Polypharmacy is a recognised burden on patients with frailty. Medication reviews as part of comprehensive geriatric assessment (CGA) ensure appropriate prescribing and minimise harms. This project aimed to develop and initiate a pharmacist delivered frailty medication review tool to enhance existing CGA within our acute frailty service.

Methods

A structured in-patient medication review tool was developed based on the STOPIT and STOPPFRAIL tools for patients with a clinical frailty score (CFS) of >4. Initial work tested this on 20 patients in our frailty ward evaluating usability and efficacy. A sample of patients seen by the acute frailty team were audited against this tool. Data was collected on falls risk medications, Anticholinergic Burden (ACB), medications stopped, medications to review and cost savings. On identifying the potential benefits, this tool was trialled by pharmacists on all elderly care wards with similar outcomes collected.

Results

Twelve acute frailty inpatients’ CGAs were audited against the tool. Five had some evidence of a polypharmacy review but no FRAX or ACB scores were completed. 58% of patients were on 3 or more 'falls medications. Overall, 19 medications should have been stopped, 5 medications could have been reduced and 14 medications highlighted for review in primary care, with a potential cost saving of £956.35/year. After initiating pharmacist reviews with the tool, 34 of 34 patients had a review, 80% of FRAX scores were documented, ACB score was completed for all patients. All patients were taking medications that increased risk of falls (average 3.5/patient) with 16 patients on ≥4. Eighty-five medications were stopped, 10 medications reduced and 33 medications highlighted for review in primary care, with a cost saving of £2755.29/year.

Conclusions

This project developed a pharmacist delivered acute frailty polypharmacy tool which enhanced existing frailty medication reviews with potential cost savings.

Hepatitis C virus exploits cyclophilin A to evade PKR

Counteracting innate immunity is essential for successful viral replication. Host cyclophilins (Cyps) have been implicated in viral evasion of host antiviral responses, although the mechanisms are still unclear. Here, we show that hepatitis C virus (HCV) co-opts the host protein CypA to aid evasion of antiviral responses dependent on the effector protein kinase R (PKR). Pharmacological inhibition of CypA rescues PKR from antagonism by HCV NS5A, leading to activation of an interferon regulatory factor-1 (IRF1)-driven cell intrinsic antiviral program that inhibits viral replication. These findings further the understanding of the complexity of Cyp-virus interactions, provide mechanistic insight into the remarkably broad antiviral spectrum of Cyp inhibitors, and uncover novel aspects of PKR activity and regulation. Collectively, our study identifies a novel antiviral mechanism that harnesses cellular antiviral immunity to suppress viral replication.

Selective Inhibition of the Mitochondrial Permeability Transition Pore Protects against Neurodegeneration in Experimental Multiple Sclerosis

The mitochondrial permeability transition pore is a recognized drug target for neurodegenerative conditions such as multiple sclerosis and for ischemia-reperfusion injury in the brain and heart. The peptidylprolyl isomerase, cyclophilin D (CypD, PPIF), is a positive regulator of the pore, and genetic down-regulation or knock-out improves outcomes in disease models. Current inhibitors of peptidylprolyl isomerases show no selectivity between the tightly conserved cyclophilin paralogs and exhibit significant off-target effects, immunosuppression, and toxicity. We therefore designed and synthesized a new mitochondrially targeted CypD inhibitor, JW47, using a quinolinium cation tethered to cyclosporine. X-ray analysis was used to validate the design concept, and biological evaluation revealed selective cellular inhibition of CypD and the permeability transition pore with reduced cellular toxicity compared with cyclosporine. In an experimental autoimmune encephalomyelitis disease model of neurodegeneration in multiple sclerosis, JW47 demonstrated significant protection of axons and improved motor assessments with minimal immunosuppression. These findings suggest that selective CypD inhibition may represent a viable therapeutic strategy for MS and identify quinolinium as a mitochondrial targeting group for in vivo use.

Phthalazinone pyrazoles as potent, selective, and orally bioavailable inhibitors of Aurora-A kinase

The inhibition of Aurora kinases in order to arrest mitosis and subsequently inhibit tumor growth via apoptosis of proliferating cells has generated significant discussion within the literature. We report a novel class of Aurora kinase inhibitors based upon a phthalazinone pyrazole scaffold. The development of the phthalazinone template resulted in a potent Aurora-A selective series of compounds (typically >1000-fold selectivity over Aurora-B) that display good pharmacological profiles with significantly improved oral bioavailability compared to the well studied Aurora inhibitor VX-680.

Annotation of environmental OMICS data: application to the transcriptomics domain

Researchers working on environmentally relevant organisms, populations, and communities are increasingly turning to the application of OMICS technologies to answer fundamental questions about the natural world, how it changes over time, and how it is influenced by anthropogenic factors. In doing so, the need to capture meta-data that accurately describes the biological "source" material used in such experiments is growing in importance. Here, we provide an overview of the formation of the "Env" community of environmental OMICS researchers and its efforts at considering the meta-data capture needs of those working in environmental OMICS. Specifically, we discuss the development to date of the Env specification, an informal specification including descriptors related to geographic location, environment, organism relationship, and phenotype. We then describe its application to the description of environmental transcriptomic experiments and how we have used it to extend the Minimum Information About a Microarray Experiment (MIAME) data standard to create a domain-specific extension that we have termed MIAME/Env. Finally, we make an open call to the community for participation in the Env Community and its future activities.

The role of arginine vasotocin in teleost fish osmoregulation

The AVT system is a key component of the complex mechanism responsible for coordinating the response in teleost fish to hyper-osmotic challenge. The pituitary AVT store falls following transfer to SW from FW and this is accompanied by an increase in circulating AVT levels. This indicates that there has been release of AVT in response to this stimulus and the system is being up-regulated. The effect of an increase in secretion would appear to be predominantly to reduce GFR and urine production as is seen when AVT is injected into FW-adapted fish. This action is consistent with the requirements of hyper-osmotic challenge when water conservation becomes essential.