Potent and Selective Inhibitors of the Epidermal Growth Factor Receptor to Overcome C797S-Mediated Resistance

The epidermal growth factor receptor (EGFR) harboring activating mutations is a clinically validated target in non-small-cell lung cancer, and a number of inhibitors of the EGFR tyrosine kinase domain, including osimertinib, have been approved for clinical use. Resistance to these therapies has emerged due to a variety of molecular events including the C797S mutation which renders third-generation C797-targeting covalent EGFR inhibitors considerably less potent against the target due to the loss of the key covalent-bond-forming residue. We describe the medicinal chemistry optimization of a biochemically potent but modestly cell-active, reversible EGFR inhibitor starting point with sub-optimal physicochemical properties. These studies culminated in the identification of compound 12 that showed improved cell potency, oral exposure, and in vivo activity in clinically relevant EGFR-mutant-driven disease models, including an Exon19 deletion/T790M/C797S triple-mutant mouse xenograft model.

An innovative non-invasive technique for subcutaneous tumour measurements

Introduction

In oncological drug development, animal studies continue to play a central role in which the volume of subcutaneous tumours is monitored to assess the efficacy of new drugs. The tumour volume is estimated by taking the volume to be that of a regular spheroid with the same dimensions. However, this method is subjective, insufficiently traceable, and is subject to error in the accuracy of volume estimates as tumours are frequently irregular.

Methods & results

This paper reviews the standard technique for tumour volume assessment, calliper measurements, by conducting a statistical review of a large dataset consisting of 2,500 tumour volume measurements from 1,600 mice by multiple operators across 6 mouse strains and 20 tumour models. Additionally, we explore the impact of six different tumour morphologies on volume estimation and the detection of treatment effects using a computational tumour growth model. Finally, we propose an alternative method to callipers for estimating volume–BioVolume^TM, a 3D scanning technique. BioVolume simultaneously captures both stereo RGB (Red, Green and Blue) images from different light sources and infrared thermal images of the tumour in under a second. It then detects the tumour region automatically and estimates the tumour volume in under a minute. Furthermore, images can be processed in parallel within the cloud and so the time required to process multiple images is similar to that required for a single image. We present data of a pre-production unit test consisting of 297 scans from over 120 mice collected by four different operators.

Conclusion

This work demonstrates that it is possible to record tumour measurements in a rapid minimally invasive, morphology-independent way, and with less human-bias compared to callipers, whilst also improving data traceability. Furthermore, the images collected by BioVolume may be useful, for example, as a source of biomarkers for animal welfare and secondary drug toxicity / efficacy.

Abstract 4451: Evaluation of the therapeutic potential of phosphine oxide pyrazole inhibitors in tumors harboring EGFR C797S mutation

Osimertinib is a next-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) with activity against both the activating and the ‘gatekeeper’ T790M EGFR mutations. An acquired EGFR C797S mutation has been reported to mediate osimertinib resistance in approximately 15% and 7% of patients in second-line and first-line treatment respectively. This percentage in the first-line setting will likely evolve as the first line data mature. The C797S mutation leads to the loss of covalent binding of osimertinib to mutant EGFR. The high affinity of the EGFR triple mutant for ATP presents a challenge for reversible inhibitor design, particularly as the loss of the cysteine at position 797 precludes the previously exploited covalent approaches. We have explored various approaches to address this challenge, including an effort to maximise reversible affinity to target the C797S mutation without requiring a covalent bond. We describe herein the therapeutic potential of reversible phosphine oxide pyrazole inhibitors in tumors harboring C797S.

Using structure-based design, we were able to design a series of phosphine oxide pyrazole inhibitors that displayed exceptionally high biochemical potency against EGFR C797S mutation, which translated into good activity in cell-based assays. Using CRISPR-Cas 9 genome editing technology, we engineered cellular disease-relevant models to express the C797S mutation to evaluate potency in vitro and in vivo.

By modulating the physicochemical properties of our in vitro leads, we were able to achieve good oral exposure of cellularly active EGFR C797S inhibitors such as AZ’7608. We showed that AZ’7608 inhibits signalling pathways and cellular growth of C797S EGFR cell lines in vitro and demonstrated an improved WT EGFR margin. This translated into 52% (p<0.05, at day 14) tumor growth inhibition in vivo when compared to the control group. The efficacy of AZ’7608 is enhanced by its combination with anti-EGFR antibody, showing tumor regression (82%, p<0.001). In addition, we performed pharmacodynamic studies to explore the relationship between efficacy and target/pathway modulation. These studies establish a clear relationship between depth and duration of inhibition of the phosphorylation of EGFR and anti-tumor efficacy.

The work presented herein shows a proof of concept for reversible phosphine oxide pyrazole inhibitors to target tumors harboring C797S. The emergence of the C797S EGFR mutation remains a key area of unmet need and warrants further efforts in drug discovery.

Citation Format: Nicolas Floch, M. Raymond V. Finlay, Ambra Bianco, Sue Bickerton, Nicola Colclough, Darren A. Cross, Emanuela M. Cuomo, Carine M. Guerot, David Hargreaves, Matthew J. Martin, Darren McKerrecher, Daniel J. O’Neill, Jonathan P. Orme, Amar Rahi, Paul D. Smith, Richard A. Ward. Evaluation of the therapeutic potential of phosphine oxide pyrazole inhibitors in tumors harboring EGFR C797S mutation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4451.

Abstract 1828: Are callipers obsolute? A novel 3D scanning technology to measure subcutaneous tumor volume

Most preclinical oncology studies (xenograft, PDX, GEMMS) involve monitoring tumour growth rates, measuring them with callipers, and calculating the volume. Volume is calculated from the width and the length to estimate a 3D volume and is directly used to assess treatment efficacy. Although this technique is useful, it is unable to accurately assess non-uniformly shaped or very small tumours and introduces a systematic bias by assuming that tumours present with spheroid shape. Furthermore callipers do not inform of the tumour condition, which is dependent upon a visual estimation.

Here we describe the development and validation of a 3D scanner as an alternative method to callipers to monitor tumour progression in rodents. The resulting 3D scanner solution made up of hardware and software, has the potential to impact on the 3Rs guiding principles underpinning the humane use of animals in oncology research. The 3Rs benefits identified are primarily through reduction of animals via improved data accuracy allowing reduction in group sizes or the ability to include irregularly shaped tumours to test. In addition the scanner system described will make it possible to record tumour measurements in a rapid, minimally invasive, morphology-independent, and human-bias-free way, removing interoperator variability. This photo-based technique captures external symptoms of redness, paleness, ulceration of tumours, etc., which could ultimately be used to detect early toxicities of compounds or determine scales of animal welfare.

We describe the development and early validation of the scanner system within our laboratories. Using the 3D scanner alongside tumour callipers to monitor tumour growth of Oncology tumour studies we demonstrated that we can accurately measure tumour size parameters (length, width and volume) in multiple mouse strains and across a range of tumour models. 3D scanning tumour data is comparable to tumour measures generated from tumour callipers If successful the introduction of this system to replace tumour callipers could have a large impact for groups running oncology in-vivo tumour studies.

Citation Format: Zena Wilson, Juan Delgado, Michael Davies, Rebecca Whiteley, Jennifer Hare, Amar Rahi, Stephen Marshall, Andrew Smith, Stephen Atkinson, Jarno Ralli, Adeala Zabair, Adeala Zabair, Jane Kendrew. Are callipers obsolute? A novel 3D scanning technology to measure subcutaneous tumor volume [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1828. doi:10.1158/1538-7445.AM2017-1828

A label-free, PCR-free and signal-on electrochemical DNA biosensor for Leishmania major based on gold nanoleaves

Detection of leishmaniasis is important in clinical diagnoses. In the present study, identification of Leishmania parasites was performed by a label-free, PCR-free and signal-on ultrasensitive electrochemical DNA biosensor. Gold nanoleaves were firstly electrodeposited by an electrodeposition method using spermidine as a shape directing agent. The biosensor was fabricated by immobilization of a Leishmania major specific DNA probe onto gold nanoleaves, and methylene blue was employed as a marker. Hybridization of the complementary single stranded DNA sequence with the biosensor under the selected conditions was then investigated. The biosensor could detect a synthetic DNA target in a range of 1.0×10^-10 to 1.0×10^-19molL^-1 with a limit of detection of 1.8×10^-20molL^-1, and genomic DNA in a range of 0.5-20ngμL^-1 with a limit of detection of 0.07ngμL^-1. The biosensor could distinguish Leishmania major from a non-complementary-sequence oligonucleotide and the tropica species with a high selectivity. The biosensor was applicable to detect Leishmania major in patient samples.

Label-free electrochemical aptasensing of the human prostate-specific antigen using gold nanospears

Gold nanospears were electrodeposited with the assistance of arginine as a soft template and precise selection of experimental parameters. The nanospears were then employed as a transducer to immobilize an aptamer of prostate-specific antigen (PSA) and fabrication of a label-free electrochemical aptasensor. The aptasensor was employed for the detection of PSA with a linear concentration range of 0.125-200ngmL(-1) and a limit of detection of 50pgmL(-1). The aptasensor was successfully applied to detect PSA in blood serum samples of healthy and patient persons.

Nanostructured materials in electroanalysis of pharmaceuticals

Basic strategies and recent developments for the enhancement of the sensory performance of nanostructures in the electroanalysis of pharmaceuticals are reviewed. A discussion of the properties of nanostructures and their application as modified electrodes for drug assays is presented. The electrocatalytic effect of nanostructured materials and their application in determining low levels of drugs in pharmaceutical forms and biofluids are discussed.

Synthesis and Applications of Nanoflowers

BACKGROUND

Recent advances in nanotechnology make novel shapes of nanostructured materials with novel physicochemical properties. Different kinds of materials including carbon, metals, alloys, metal oxides, conducting polymers, metal chalcogenides, pnictides and fluorides have been synthesized with small size of <100 nm with shapes resembled to the natural flowers. The objective of this review is to provide a broad overview of the synthesis strategies, effects of different parameters on the morphology of nanoflowers, and their applications.

METHODS

A comprehensive search to assess the current evidence for the synthesis routs of nanoflowers and applications was conducted. 487 studies became selected and the quality of papers were appraised and categorized according to type of nanomaterials. Within each section, the nanomaterials addressed specifically. In addition, recent patents were reviewed in a separate section.

RESULTS

The nanoflowers exhibited unique properties which were utilized in the design of efficient applications. These nanostructures can be processed with different methods. The configuration of flower-like nanostructures can be controlled by altering experimental parameters, such as the precursor`s ratio, temperature and reaction time. Despite the huge efforts to control and understand the growth mechanism of these nanostructures, some fundamental phenomena are still not well understood. Investigation of the fundamental effects of size and morphology on their properties is required in order to better apply these nanostructured materials.

CONCLUSION

The nanoflowers with interesting properties can be used in the design of future devices with various applications. The existence of different routes to synthesis nanoflowers and their unique properties confirm the importance promoted awareness of potential benefits of nanoflowers in different applications. The reviewed patents emphasized the importance of these nanostructures. Therefore, research efforts based on nanoflowers are dynamic and applicable in various fields.

AZD9291, an irreversible EGFR TKI, overcomes T790M-mediated resistance to EGFR inhibitors in lung cancer

First-generation EGFR tyrosine kinase inhibitors (EGFR TKI) provide significant clinical benefit in patients with advanced EGFR-mutant (EGFRm(+)) non-small cell lung cancer (NSCLC). Patients ultimately develop disease progression, often driven by acquisition of a second T790M EGFR TKI resistance mutation. AZD9291 is a novel oral, potent, and selective third-generation irreversible inhibitor of both EGFRm(+) sensitizing and T790M resistance mutants that spares wild-type EGFR. This mono-anilino-pyrimidine compound is structurally distinct from other third-generation EGFR TKIs and offers a pharmacologically differentiated profile from earlier generation EGFR TKIs. Preclinically, the drug potently inhibits signaling pathways and cellular growth in both EGFRm(+) and EGFRm(+)/T790M(+) mutant cell lines in vitro, with lower activity against wild-type EGFR lines, translating into profound and sustained tumor regression in EGFR-mutant tumor xenograft and transgenic models. The treatment of 2 patients with advanced EGFRm(+) T790M(+) NSCLC is described as proof of principle.

SIGNIFICANCE

We report the development of a novel structurally distinct third-generation EGFR TKI, AZD9291, that irreversibly and selectively targets both sensitizing and resistant T790M(+) mutant EGFR while harboring less activity toward wild-type EGFR. AZD9291 is showing promising responses in a phase I trial even at the first-dose level, with first published clinical proof-of-principle validation being presented.

Comparison of carotid Doppler ultrasound and computerised tomographic angiography in the evaluation of carotid artery stenosis

PURPOSE

To compare results of carotid Doppler ultrasound (CDUS) and spiral computerised tomographic angiography (CTA) in patients with suspected carotid artery stenosis and to evaluate their combined effect on decision making for carotid endarterectomy (CEA).

METHODS

A total of 107 patients were studied. All of the patients had CDUS followed by CTA as a standard method of investigation. Data included the indications for investigation, stenosis degree measured in both modalities, in addition to difficulties and limitations faced while doing them.

RESULTS

Out of the 214 carotid scans performed, 187 scans were included in the comparison, while 27 scans were excluded due to inadequate data or imaging difficulties. The overall concordance between both CDUS and CTA was 79.1% (148/187) (95% CI 0.72-0.83). CDUS under-estimated and over-estimated the degree of stenosis in 26/187 (14%, 95% CI 0.09-0.19) and 13/187 (7%, 95% CI 0.04-0.12), respectively. When CTA was considered in conjunction with CDUS, the decision regarding operative treatment was changed in 29/187 cases (16%) (95% CI 0.11-0.21).

CONCLUSIONS

CDUS remains the first line non-invasive imaging for carotid artery stenosis. However, in cases where it is inconclusive, CTA is an excellent, reliable, minimally invasive, and outpatient alternative for patient selection for CEA.

Genotyping human platelet alloantigens (HPA 1-5) in Saudis from Eastern Province, Saudi Arabia

In this study we report for the first time the distribution of human platelet alloantigens [HPA]in Saudis. These antigens are implicated in the pathophysiology of alloimmune thrombocytopenia. We collected blood samples from 84 healthy male Saudi blood donors. DNA isolated by salting-out and ethanol precipitation was amplified for genes HPA 1-5 using the polymerase chain reaction/sequence specific primer method. We found high HPA-1 polymorphism similar to Caucasians. HPA-4 polymorphism in Saudis was, however, greater than in Caucasians, and more similar to that of the Japanese. These results suggest that both these two HPA systems may be clinically important in Saudis

Genotyping human platelet alloantigens (HPA 1-5) in Saudis from Eastern Province, Saudi Arabia

In this study we report for the first time the distribution of human platelet alloantigens (HPA) in Saudis. These antigens are implicated in the pathophysiology of alloimmune thrombocytopenia. We collected blood samples from 84 healthy male Saudi blood donors. DNA isolated by salting-out and ethanol precipitation was amplified for genes HPA 1-5 using the polymerase chain reaction/sequence specific primer method. We found high HPA-1 polymorphism similar to Caucasians. HPA-4 polymorphism in Saudis was, however, greater than in Caucasians, and more similar to that of the Japanese. These results suggest that both these two HPA systems may be clinically important in Saudis.

Immunodiagnosis of ocular chlamydial infection

The diagnostic roles of enzyme immunoassay and indirect immunofluorescence tests were studied in 99 patients with various grades of active trachoma and in 72 patients with inactive trachoma. Normal individuals and patients with non-specific chronic conjunctivitis were used as a control group. Chlamydial antigens were detected in the conjunctival swabs from a large proportion of patients with severe or moderate trachoma. Cases with 'antigen-negative' but clinically severe trachoma showed presence of specific IgG in the blood, thus indicating that serological tests may complement the ELISA test for the detection of chlamydia in infected tissues. The nature of cellular reaction in the conjunctiva seems to be related to the severity of trachoma and presence of the infective organism. 'Antigen-negative' trachoma thus represents either an error of diagnosis or limited sensitivity of currently available immunologic techniques, or a predominantly hypersensitivity state triggered by transient tissue parasitism. Recombinant DNA technology and chronobiologic study of infiltrating lymphocytes are likely to provide some insight in such cases.

Antibodies to skeletal muscle actin and their reactivity with malignant melanoma of the choroid

Imprints of choroidal malignant melanoma cells were treated with serum containing antibodies to a purified preparation of actin derived from skeletal muscle. Evidence of a positive reaction, as shown by indirect immunofluorescence, substantiated an impression based on morphological criteria that choroidal melanoma cells contain actin protein. The significance of this protein in tumour biology is discussed, and a possible interference by antiactin antibodies in the immunodiagnosis of choroidal melanoma is highlighted.

Immunological investigations in post-traumatic granulomatous and non-granulomatous uveitis

Histopathological and immunological investigations have been performed in 16 cases of post-traumatic granulomatous (10) and non-granulomatous uveitis (6). Most cases of sympathetic ophthalmitis showed evidence of cell mediated immunity to uveoretinal antigens, though it was not possible to make a definitive diagnosis on immunological grounds alone. Three patients with post-traumatic non-granulomatous uveitis showed a positive immunological response to ocular antigens, and 2 of these later developed clinical evidence of sympathetic ophthalmitis, which suggests that post-traumatic non-granulomatous uveitis in such cases may represent a presympathetic (i.e., incipient) or modified stage of the disease.

Contractile proteins in retinal endothelium and other non-muscle tissues of the eye

The present study is the first investigation to demonstrate, by employing the combined approach of immunologically and electron microscope methods, the presence of actin-like contractile proteins in the mammalian retina, the corneal epithelium and endothelium, the iris, and the ciliary body, and to confirm their presence in lens epithelium. This is also the first report to demonstrate by these methods the presence of microfilaments and intermediate filaments in retinal vascular endothelium. Since we have shown that actin filaments are especially abundant in immature retinal endothelial cells, the question of their function arises, and we have discussed their possible relevance to the closure of immature retinal vessels when exposed to hyperoxia.

Keratoconus and coexisting atopic disease

The association of keratoconus and atopic disease has been reported on several occasions but the only controlled clinical study that has so far been published found no evidence to support this view. Since it is now known that atopy is often associated with changes in various immunoglobulins, particularly IgE, it was considered desirable to determine the immunological profiles of a large series of keratoconus cases in order to seek evidence for coexistence of the two conditions in one individual. In this study of 182 cases of keratoconus a definite history of atopy was found in 35% compared with 12% in the matched control group. The serum IgE was significantly raised (P less than 0.001) in keratoconus and markedly so in those cases with associated atopic disease. Serum levels of IgG and IgM were also raised, but contrary to the findings of other observers IgA levels were normal. These findings suggest that atopic traits are more common in patients with keratoconus than in general ophthalmic patients.

Reticulum fibres in relation to retinal vessels

Argyrophilic perivascular and intervascular fibres in the mammalian retina are shown by specific antireticulin immunofluorescence to consist of reticulin. The possible significance of these findings is briefly discussed.