Introducing physician associates to hospital patients: Development and feasibility testing of a patient experience-based intervention.

BACKGROUND: Physician associates (PAs) are one of many new mid-level health practitioner roles being introduced worldwide. They are a recent innovation in English hospitals. Patient confusion with novel mid-level practitioner titles and roles is well documented, alongside evidence of a positive association between patients' ability to identify practitioners and patient satisfaction. No prior research developed an intervention to introduce PAs or any other new practitioner role to hospital patients. OBJECTIVE: To develop, with patient and public involvement and engagement (PPIE), an intervention for introducing the PA role to hospital patients, and to test feasibility. METHODS: Intervention development was underpinned by an experience-based co-design approach. Workshop participants generated ideas for introducing PAs, subsequently explored in semi-structured interviews with hospital patients (n = 13). Interview findings were used by participants in a second workshop to design the intervention. Feasibility of the intervention was assessed in relation to its acceptability and efficacy using semi-structured interviews with hospital patients (n = 20) and PAs (n = 3). RESULTS: The intervention developed was a patient information leaflet. It was considered feasible to use in the hospital setting, helpful to patients in understanding the PA role and acceptable to both patients and PAs. The intervention was also appreciated by patients for providing reassurance of care and support. CONCLUSIONS: An experience-based co-design approach enabled development of an intervention tailored to patients' experiential preferences. Positive evidence of feasibility and utility is encouraging, supporting future larger-scale testing. PATIENT AND PUBLIC CONTRIBUTION: PPIE representatives were involved in the study design, intervention development and data interpretation.

Bioisosteric Discovery of NPA101.3, a Second-Generation RET/VEGFR2 Inhibitor Optimized for Single-Agent Polypharmacology.

RET receptor tyrosine kinase is a driver oncogene in human cancer. We recently identified the clinical drug candidate Pz-1, which targets RET and VEGFR2. A key in vivo metabolite of Pz-1 is its less active demethylated pyrazole analogue. Using bioisosteric substitution methods, here, we report the identification of NPA101.3, lacking the structural liability for demethylation. NPA101.3 showed a selective inhibitory profile and an inhibitory concentration 50 (IC50) of <0.003 µM for both RET and VEGFR2. NPA101.3 inhibited phosphorylation of all tested RET oncoproteins as well as VEGFR2 and proliferation of cells transformed by RET. Oral administration of NPA101.3 (10 mg/kg/day) completely prevented formation of tumors induced by RET/C634Y-transformed cells, while it weakened, but did not abrogate, formation of tumors induced by a control oncogene (HRAS/G12V). The balanced synchronous inhibition of both RET and VEGFR2, as well the resistance to demethylation, renders NPA101.3 a potential clinical candidate for RET-driven cancers.

A secondary RET mutation in the activation loop conferring resistance to vandetanib.

Resistance to vandetanib, a type I RET kinase inhibitor, developed in a patient with metastatic lung adenocarcinoma harboring a CCDC6-RET fusion that initially exhibited a response to treatment. The resistant tumor acquired a secondary mutation resulting in a serine-to-phenylalanine substitution at codon 904 in the activation loop of the RET kinase domain. The S904F mutation confers resistance to vandetanib by increasing the ATP affinity and autophosphorylation activity of RET kinase. A reduced interaction with the drug is also observed in vitro for the S904F mutant by thermal shift assay. A crystal structure of the S904F mutant reveals a small hydrophobic core around F904 likely to enhance basal kinase activity by stabilizing an active conformer. Our findings indicate that missense mutations in the activation loop of the kinase domain are able to increase kinase activity and confer drug resistance through allosteric effects.

Effect of Dickkopf1 on the senescence of melanocytes: in vitro study.

Fibroblasts secrete several growth factors which are important for the regulation of skin pigmentation. Dickkopf1 (DKK1) is also secreted by fibroblasts which inhibit the growth and function of melanocytes. Therefore, the study was designed to check the role of DKK1 in vitiligo pathogenesis. This study confirmed the higher expression of DKK1 in lesional skin of vitiligo patients. In vitro effect of DKK1 on cultured melanocytes revealed decrease in the melanocytes proliferation and pigmentation. In vitro effect of DKK1 was then checked on the melanocytes senescence and found that DKK1 induced senescence in the treated melanocytes. Expression of senescence markers was significantly higher in DKK1 treated melanocytes. This study suggests that higher expression of DKK1 in the dermis induced senescence in melanocytes that may lead to hypopigmentation and play role in vitiligo pathogenesis.

Drugging the catalytically inactive state of RET kinase in RET-rearranged tumors.

Oncogenic fusion events have been identified in a broad range of tumors. Among them, RET rearrangements represent distinct and potentially druggable targets that are recurrently found in lung adenocarcinomas. We provide further evidence that current anti-RET drugs may not be potent enough to induce durable responses in such tumors. We report that potent inhibitors, such as AD80 or ponatinib, that stably bind in the DFG-out conformation of RET may overcome these limitations and selectively kill RET-rearranged tumors. Using chemical genomics in conjunction with phosphoproteomic analyses in RET-rearranged cells, we identify the CCDC6-RETI788N mutation and drug-induced mitogen-activated protein kinase pathway reactivation as possible mechanisms by which tumors may escape the activity of RET inhibitors. Our data provide mechanistic insight into the druggability of RET kinase fusions that may be of help for the development of effective therapies targeting such tumors.

RET Functions as a Dual-Specificity Kinase that Requires Allosteric Inputs from Juxtamembrane Elements.

Receptor tyrosine kinases exhibit a variety of activation mechanisms despite highly homologous catalytic domains. Such diversity arises through coupling of extracellular ligand-binding portions with highly variable intracellular sequences flanking the tyrosine kinase domain and specific patterns of autophosphorylation sites. Here, we show that the juxtamembrane (JM) segment enhances RET catalytic domain activity through Y687. This phospho-site is also required by the JM region to rescue an otherwise catalytically deficient RET activation-loop mutant lacking tyrosines. Structure-function analyses identified interactions between the JM hinge, αC helix, and an unconventional activation-loop serine phosphorylation site that engages the HRD motif and promotes phospho-tyrosine conformational accessibility and regulatory spine assembly. We demonstrate that this phospho-S909 arises from an intrinsic RET dual-specificity kinase activity and show that an equivalent serine is required for RET signaling in Drosophila. Our findings reveal dual-specificity and allosteric components for the mechanism of RET activation and signaling with direct implications for drug discovery.

Novel imatinib derivatives with altered specificity between Bcr-Abl and FMS, KIT, and PDGF receptors.

Imatinib is a clinically important ATP analogue inhibitor that targets the tyrosine kinase domain of the intracellular Abl kinase and the PDGF receptor family. Imatinib has revolutionised the treatment of chronic myeloid leukaemia, which is caused by the oncogene Bcr-Abl and certain solid tumours that harbor oncogenic mutations of the PDGF receptor family. As a leading kinase inhibitor, imatinib also provides an excellent model system to investigate how changes in drug design impact biological activity, which is an important consideration for rational drug design. Herein we report a new series of imatinib derivatives that in general have greater activity against the family of PDGF receptors and poorer activity against Abl, as a result of modifications of the phenyl and N-methylpiperazine rings. These new compounds provide a platform for further drug development against the therapeutically important PDGF receptor family and they also provide insight into the engineering of drugs with altered biological activity.