A Novel Pan-RAS Inhibitor with a Unique Mechanism of Action Blocks Tumor Growth in Mouse Models of GI Cancer

Here we characterize a novel pan-RAS inhibitor, ADT-007, that potently and selectively inhibited the growth of histologically diverse cancer cell lines with mutant or activated RAS irrespective of the RAS mutation or isozyme. Growth inhibition was dependent on activated RAS and associated with reduced GTP-RAS levels and MAPK/AKT signaling. ADT-007 bound RAS in lysates from sensitive cells with sub-nanomolar EC 50 values but did not bind RAS in lysates from insensitive cells with low activated RAS. Insensitivity to ADT-007 was attributed to metabolic deactivation by UGT-mediated glucuronidation, providing a detoxification mechanism to protect normal cells from pan-RAS inhibition. Molecular modeling and experiments using recombinant RAS revealed that ADT-007 binds RAS in a nucleotide-free conformation to block GTP activation. Local injection of ADT-007 strongly inhibited tumor growth in syngeneic immune competent and xenogeneic immune deficient mouse models of colorectal and pancreatic cancer and activated innate and adaptive immunity in the tumor microenvironment.

SIGNIFICANCE

ADT-007 is a novel pan-RAS inhibitor with a unique mechanism of action having potential to circumvent resistance to mutant-specific KRAS inhibitors and activate antitumor immunity. The findings support further development of ADT-007 analogs and/or prodrugs with oral bioavailability as a generalizable monotherapy or combined with immunotherapy for RAS mutant cancers.

BACKGROUND

It is projected that colorectal cancer (CRC) and pancreatic ductal adenocarcinoma (PDA) will cause 52,580 and 49,830 deaths in the US in 2023, respectively (1). The 5-year survival rates for CRC and PDA are 65% and 12%, respectively (1). Over 50% of CRC and 90% of PDA patients harbor mutations in KRAS genes that are associated with poor prognosis, making the development of novel KRAS inhibitors an urgent unmet medical need (2).

Abstract 1658: ADT-007 binds RAS and inhibits RAS signaling

RAS is a critically important oncogenic protein that is mutated in approximately 1/3 of cancers resulting in aberrant activation of downstream signaling, which drives malignant transformation. Current molecular targeted therapeutics, and several in development, inhibit only specific mutant alleles (G12C, G12D). In addition, compounds which directly inhibit RAS via proteolytic degradation or inhibit RAS activation by SOS1 are in preclinical development and are referred to as Pan-KRAS inhibitors. Previously investigators have reported that the NSAID, sulindac, can selectively inhibit RAS mutant tumorigenesis by a cyclooxygenase (COX)-independent mechanism. Sulindac, and more potent analogs have also previously been reported to inhibit RAS-mediated transformation and directly bind RAS. Here we describe an ultra-potent non-COX inhibitory derivative of sulindac, ADT-007, which binds to and inhibits RAS nucleotide binding and RAS-effector association.

ADT-007 binding to KRAS was evaluated by Micro-Tag cell target engagement and by Cellular Thermal Shift Assay (CETSA) which demonstrated a potency of target engagement (EC50) value in the subnanomolar range. Consistent with molecular docking studies, HSQC NMR spectroscopy using recombinant KRAS revealed that ADT-007 interacted with KRAS after Mg2+ chelation to obtain a nucleotide free (NF) state, resulting in chemical shift changes and signal attenuation of residues in the P-loop and nucleotide binding domain. Similarly, biochemical assays confirmed that ADT-007 prevented MANT-GTP binding to recombinant NF KRAS but did not compete with bound GTP. Functional assays also showed that KRAS binding to RAF-RBD(GST) was inhibited by ADT-007. The compound inhibited constitutive RAS activation (RAF-RBD pulldown) in serum starved MiaPaCa-2 pancreatic cancer cells harboring a KRAS-G12C mutation and demonstrated Pan-RAS inhibition in serum- or EGF-stimulated cells. Further, ADT-007 inhibited AKT phosphorylation and EGF-stimulated downstream ERK1/2 phosphorylation. Finally, ADT-007 demonstrated RAS-selective growth inhibition in isogenic pancreatic and colorectal cancer cell pairs (BxPC-3, HT29). Together, these experiments support further development of ADT-007 and related analogs for treatment of RAS-driven cancers.

Citation Format: Adam B. Keeton, Xi Chen, Jacob Valiyaveettil, Chung-Hui Huang, Tyler E. Mattox, Khalda Fadlalla, Jeremy B. Foote, Donald J. Buchsbaum, Kristy L. Berry, Elmar Nurmemmedov, Ivan Babic, Vadim Gaponenko, Gregory Gorman, Lori Coward, Yulia Y. Maxuitenko, Forrest T. Smith, Gary A. Piazza. ADT-007 binds RAS and inhibits RAS signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1658.

Difluprednate-Hydroxypropyl-β-Cyclodextrin-Based Ophthalmic Solution for Improved Delivery in a Porcine Eye Model

Purpose: Difluprednate (DFP) is an approved corticosteroid, available as an ophthalmic emulsion (Durezol^®), used to treat pain and inflammation of the eye following ocular surgeries. This study utilized hydroxypropyl-β-cyclodextrin (HPBCD)-based DFP ophthalmic solution for improved ocular delivery. Methods: The DFP-HPBCD complex formation was studied in the liquid and solid states. Phase solubility, molecular docking studies, differential scanning calorimetry, and Fourier transform infrared spectroscopy suggested inclusion complexation of DFP and HPBCD. Results: DFP-HPBCD-based eye drops (solution) provided 16 and 26 times higher transcorneal permeation when compared to the suspension (no HPBCD, control) and Durezol, respectively (P < 0.001). In addition, ocular drug distribution studies conducted in continuously perfused whole porcine eyes showed DFP permeated into all of the ocular tissues in significantly higher amounts than Durezol. Conclusions: The solution-based eye drops in this study is iso-osmotic, safe, and more permeable in porcine eyes compared to Durezol.

Development and application of high-throughput screens for the discovery of compounds that disrupt ErbB4 signaling: Candidate cancer therapeutics

Whereas recent clinical studies report metastatic melanoma survival rates high as 30-50%, many tumors remain nonresponsive or become resistant to current therapeutic strategies. Analyses of The Cancer Genome Atlas (TCGA) skin cutaneous melanoma (SKCM) data set suggests that a significant fraction of melanomas potentially harbor gain-of-function mutations in the gene that encodes for the ErbB4 receptor tyrosine kinase. In this work, a drug discovery strategy was developed that is based on the observation that the Q43L mutant of the naturally occurring ErbB4 agonist Neuregulin-2beta (NRG2β) functions as a partial agonist at ErbB4. NRG2β/Q43L stimulates tyrosine phosphorylation, fails to stimulate ErbB4-dependent cell proliferation, and inhibits agonist-induced ErbB4-dependent cell proliferation. Compounds that exhibit these characteristics likely function as ErbB4 partial agonists, and as such hold promise as therapies for ErbB4-dependent melanomas. Consequently, three highly sensitive and reproducible (Z' > 0.5) screening assays were developed and deployed for the identification of small-molecule ErbB4 partial agonists. Six compounds were identified that stimulate ErbB4 phosphorylation, fail to stimulate ErbB4-dependent cell proliferation, and appear to selectively inhibit ErbB4-dependent cell proliferation. Whereas further characterization is needed to evaluate the full therapeutic potential of these molecules, this drug discovery platform establishes reliable and scalable approaches for the discovery of ErbB4 inhibitors.

Shear flow over flexible three-dimensional patches in a surface

Slowly varying shear flow is considered over one or more flexible three-dimensional patches in a surface inside a boundary layer. At certain shear values, resonances emerge in which the effects on flow and patch shape are enlarged by an order of magnitude. Fast evolution then occurs: this leads to fully nonlinear unsteady interaction, after some delay, combining with finite-time break-ups to form a distinct path into transition.This article is part of the theme issue 'Modelling of sea-ice phenomena'.

Improved Ocular Delivery of Nepafenac by Cyclodextrin Complexation

Nepafenac is a nonsteroidal anti-inflammatory drug (NSAID), currently only available as 0.1% ophthalmic suspension (Nevanac®). This study utilized hydroxypropyl-β-cyclodextrin (HPBCD) to increase the water solubility and trans-corneal permeation of nepafenac. The nepafenac-HPBCD complexation in the liquid and solid states were confirmed by phase solubility, differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance spectroscopy (NMR) analyses. Nepafenac 0.1% ophthalmic solution was formulated using HPBCD (same pH and osmolality as that of Nevanac®) and pig eye trans-corneal permeation was studied versus Nevanac®. Furthermore, nepafenac content in cornea, sclera, iris, lens, aqueous humor, choroid, ciliary body, retina, and vitreous humor was studied in a continuous isolated pig eye perfusion model in comparison to the suspension and Nevanac®. Permeation studies using porcine corneas revealed that the solution formulation had a permeation rate 18 times higher than Nevanac®. Furthermore, the solution had 11 times higher corneal retention than Nevanac®. Drug distribution studies using porcine eyes revealed that the solution formulation enables detectable levels in various ocular tissues while the drug was undetectable by Nevanac®. The ocular solution formulation had a significantly higher drug concentration in the cornea compared to the suspension or Nevanac®.

Analytical differentiation of 1-alkyl-3-acylindoles and 1-acyl-3-alkylindoles: isomeric synthetic cannabinoids

The 1-alkyl-3-acylindoles and the inverse regioisomeric 1-acyl-3-alkylindoles can be prepared directly from a common set of precursor materials and using similar synthetic strategies. The EI mass spectra for these isomers show a number of unique ions which allow for the differentiation of the 1-alkyl-3-acylindole compounds from the inverse regioisomeric 1-acyl-3-alkylindoles. The base peak at m/z 214 in the 1-n-pentyl-3-benzoylindole represents the M-77 cation fragment resulting from the loss of the phenyl group, and this ion is not observed in the inverse isomer. The 1-benzoyl-3-n-pentylindole inverse regioisomer shows a base peak at m/z 105 for the benzoyl cation. Thus, these two base peaks are the result of fragmentation initiated at the carbonyl-oxygen for both isomers. The 1-pentyl-3-benzoylindole is characterized by the strong intensity carbonyl band at 1703 cm(-1), while the amide carbonyl appears as a strong band of equal intensity at 1681 cm(-1) in the 1-benzoyl-3-pentyl regioisomer.

Multi-branching flows from one mother tube to many daughters or to a network

Multiply branching fluid flows are modelled in two contexts. The first (type I) is for one-to-many branching. Computations are described for flow through a channel, with fully developed motion upstream, which branches abruptly into a number of subchannels downstream. The differences in pressure between the upstream end of the channel and the downstream ends of the subchannels are substantial. Comparisons with recent analytical predictions show fair agreement for Reynolds numbers in the low tens and above. The second context (type II) has successive generations of bifurcation in a network. Modelling, computations and analysis include the effects of many bifurcations.

Modelling the calmed region behind a spot

A theoretical model of the laminar 'calmed region' following a three-dimensional turbulent spot within a transitioning two-dimensional boundary layer is formulated and discussed. The flow is taken to be inviscid, and the perturbation mean flow surface streamlines calculated represent disturbances to the basic slip velocity. Available experimental evidence shows a fuller, more stable, streamwise profile in a considerable region trailing the spot, with cross-flow 'inwash' towards the line of symmetry. Present results are in qualitative agreement with this evidence.

Droplet impact on water layers: post-impact analysis and computations

An inviscid model of droplet impact into a water layer is examined analytically for small times just after impact and computationally for order-one distortion times. Various layer depths are considered, as are surface-tension effects. Good correspondence is found between analysis, computation and experiments.

AVM modelling by multi-branching tube flow: large flow rates and dual solutions

Cerebral arteriovenous malformations (AVMs) present a common yet complex clinical challenge, through 'steal' phenomena, haemorrhage risks and epilepsy effects, aspects which are little understood even for individual lesions. The main difficulty lies in understanding the detailed haemodynamics of AVMs and especially the enhanced through-flow associated with steal. Mathematically, as a basic step, the paper investigates a nonlinear inviscid model for the planar incompressible flow of fluid through a branched geometry consisting of a single feeding mother tube which splits into two or more non-aligned daughter tubes. Recurrence relations between the unknown flow profiles in the daughter tubes and the incoming rotational flow profile in the mother tube are derived, analysed, and solved in detail in order to find the total flow rate. The results show greatly enhanced through-flow arising, for a fixed value of the total downstream flow area, either from non-unique solutions to the problem or more particularly from an increase in the number of daughter tubes, or from both, depending on the distribution of pressure differences applied across the branching region and the total downstream flow area. Extensions of the basic flow model are noted, along with comparisons with recent direct numerical simulations and discussion of possible repercussions in the context of treatment and clinical observations of enhanced through-flows in AVMs.

On flow through bends and branchings

Theoretical modelling of bending and branching tube flows at medium-to-high flow rates is described for current industrial and biomedical projects. This mostly uses slender-flow modelling. Much pressure loss occurs in bends, with increased swirl, large variations in velocity components and wall shear stress, skewing of the downstream motion and reduced flow rate, but the flow regime which is established shows sensitive dependence on the imposed pressure drop and entrance conditions. A small side-branch off a mother tube produces most rapid variation in pressure and velocity near the daughter entrance, this variation now being quantifiable. A multiple branching yields large flow rates and nonunique flow patterns, depending on the form of the imposed pressure differences.

Activated protein C resistance, factor V Leiden and peripheral vascular disease

Activated protein C resistance caused by factor V Leiden is an important thrombophilia disorder which predisposes to venous thromboembolism. Some studies also suggest a role in the pathogenesis of arterial thrombosis and atherosclerosis. The authors have investigated the prevalence of activated protein C resistance and factor V Leiden in a series of 45 patients with peripheral vascular disease. Twelve patients were receiving warfarin. The activated protein C resistance ratios were significantly lower in the group of 33 non-warfarinized patients with peripheral vascular disease (median 2.82 (range 1.36-3.83)) compared with 33 age- and sex-matched controls (median 2.97 range 2.24-4.11); P<0.005; Wilcoxon rank sum). Eight patients (24%) had activated protein C resistance (ratio <2.2). The prevalence of factor V Leiden in patients with peripheral vascular disease was 17.8% (8/45). This is significantly increased compared with the local population and UK published frequency of 3.5% for this genotype. The presence of factor V Leiden did not affect the late outcome of arterial reconstructive surgery in terms of graft patency (P=0.5, Fisher's Exact test).

Effects of [(N-alkyl-1,3-dihydro-1-oxoisoindolin-5-yl)oxy]alkanoic acids on chloride transport in primary astroglial cultures

It has been demonstrated that agents which inhibit chloride influx and, therefore, lower intracellular chloride levels in the astrocyte, a major cell type in the cerebral gray matter, inhibit astrocytic swelling in vitro and in vivo. Herein, we report additional examples of a series of [(N-alkyl-1,3-dihydro-1-oxoisoindolin-5-yl)oxy]alkanoic acids and their effects upon ion transport in primary rat astrocyte cultures. The 4-chloro-substituted 1-oxoisoindolines demonstrated superior astrocytic chloride influx inhibitory activity as compared to the 6-chloro and non-chlorinated analogs. The four-carbon acid side chain derivatives were more active than the three- and two-carbon analogs. The pharmacological profile of these compounds was examined with respect to inhibition of the Cl(-)-Cl-/Cl(-)-HCO3- anion exchanger and Na(+)-K(+)-2Cl- cotransport mechanisms in glia, and the compounds were found to exhibit a similar profile to that of furosemide by inhibiting both transporters.

Inhibition of membrane fusion by lysophosphatidylcholine

The ability of lysophosphatidylcholine to inhibit membrane fusion at subsolubilizing concentrations (between 1 and 9 mol % with respect to the membrane lipids) was examined. Fusion between N-methyldioleoylphosphatidylethanolamine (DOPE) large unilamellar vesicles (LUV) and fusion between Sendai virus and N-methyl-DOPE LUV were measured. A contents mixing fusion assay was used for LUV fusion (ANTS/DPX), and a lipid mixing assay (octadecylrhodamine B) was used for the virus fusion experiments. Lysophosphatidylcholine was effective at inhibiting both LUV fusion and Sendai virus/LUV fusion. Lysophosphatidylcholine also inhibited leakage from N-methyl-DOPE LUV, 31P nuclear magnetic resonance data were obtained of N-methyl-DOPE in the presence of lysophosphatidylcholine. Lysophosphatidylcholine stabilized the lamellar phase and reduced the incidence of nonlamellar structures at all temperatures. The destabilization of nonlamellar structures with a negative radius of curvature may be a mechanism for inhibition of fusion by lysophosphatidylcholine in these systems.

Conformational analysis, molecular modeling, and quantitative structure-activity relationship studies of agents for the inhibition of astrocytic chloride transport

Molecular modeling studies were carried out on a series of 1-oxoisoindolines which are pharmacologically active as inhibitors of astrocytic chloride transport. Conformational analysis revealed that the halogen substituent exerted a pronounced steric directing effect on the acid side chain. The 4-substituted analogs apparently provided for the best spatial arrangement of pharamacophoric elements of the molecules. Conventional quantitative structure-activity relationship (QSAR) studies using lipophilic and dipole moment characteristics of the molecules as physical descriptor variables in the regression equation yielded a statistically significant model. Comparative molecular field analysis (CoMFA) was utilized as a three-dimensional QSAR technique to explore changes in the steric and electrostatic fields of the molecules that can account for differences in biological activity values. A highly predictive model was attained which supported the results from the qualitative and conventional quantitative structure-activity relationship analyses. These modeling techniques represent the evolutionary process by which structure-activity methods were employed to aid in the development of novel more potent inhibitors of astrocytic chloride transport.

The antiviral peptide carbobenzoxy-D-phenylalanyl-L-phenylalanylglycine changes the average conformation of phospholipids in membranes

The influence of the antiviral peptide, carbobenzoxy-D-phenylalanyl-L-phenylalanylglycine (ZfFG), on the average conformation of phosphatidylcholine in hydrated bilayers was investigated with multinuclear solid state magnetic resonance (NMR). Phosphatidylcholine was specifically deuterated (separately) in the choline N-methyls, the alpha and beta positions of the choline, the C2 carbon of the acyl chains, and at all the carbons of the acyl chains of the phosphatidylcholine. Phosphatidylcholine was also synthesized with the carbonyl carbons of the ester bonds between the glycerol and the hydrocarbon chains enriched in 13C. 2H NMR of the phosphatidylcholine perdeuterated in the acyl chains showed a loss of intensity from the deuteriums with the largest quadrupole splitting in the presence of ZfFG, while the remainder of the powder pattern was largely unaffected. The phosphatidylcholine specifically deuterated at the C2 carbon (representative of the C-D bonds giving rise to the largest quadrupole splittings) showed the same loss of intensity suggesting changes in the phospholipid conformation and conformational dynamics near the glycerol. Analysis of the powder patterns in the 13C NMR spectrum of phosphatidylcholine labeled with 13C in the carbonyl carbons revealed a significant change in the average orientation of the sn-1 carbonyl due to the presence of the ZfFG and no change in the sn-2 carbonyl orientation. Changes in the headgroup conformation, as detected by 2H NMR of the deuteriums in the alpha and beta methylenes of the choline headgroup and 31P NMR of the phosphate segment, reflected the electrostatic nature of the interaction of the carboxyl of ZfFG with phosphatidylcholine bilayers.(ABSTRACT TRUNCATED AT 250 WORDS)

Liquid chromatographic studies on the aqueous solution conformation of substituted benzamides related to remoxipride

A series of disubstituted benzamides related to the sterically hindered 2,6-dimethoxybenzamide drugs, such as remoxipride, are prepared. The structure-retention relationships for these compounds are studied on hydrocarbon stationary phases in various hydroorganic mobile phases. The 2,6-dimethoxybenzamide displays a very low capacity factor under these reversed-phase conditions, suggesting that steric crowding prevents the formation of an amide-methoxy N-H...O intramolecular hydrogen bond. The corresponding 2-hydroxy-6-methoxybenzamide shows a dramatic increase in affinity for the hydrocarbon stationary phase, which is characteristic of strong intramolecular hydrogen bonding in these compounds. These results suggest that the aromatic ring--carbonyl aqueous solution conformation is almost 90 degrees in amides like remoxipride and changes to coplanarity upon demethylation of one methoxy group.

Antitumor agents. 89. Psychorubrin, a new cytotoxic naphthoquinone from Psychotria rubra and its structure-activity relationships

A new naphthoquinone, isolated from the alcoholic extract of Psychotria rubra, exhibited significant cytotoxicity in the KB cell assay (ED50 = 3.0 micrograms/mL). Spectral data was used to assign the structure of psychorubrin as 2. Naphthoquinone derivatives 6, 8, 13, and 14 were prepared and exhibited superior cytotoxic activity to that of psychorubrin. All were potential Michael acceptors whose conjugation had been extended. However, when a hydrophilic hydroxy group was present in such compounds, reduced in vitro activity was observed.

Effects of [(N-alkyl-1,3-dioxo-1H,3H-isoindolin-5-yl)oxy]alkanoic acids, [(N-alkyl-1-oxo-1H,3H-isoindolin-5-yl)oxy]butanoic acids, and related derivatives on chloride influx in primary astroglial cultures

It has been shown that agents that inhibit chloride influx and therefore lower intracellular chloride levels in a major cell type in cerebral gray matter, the astrocyte, inhibit astrocytic swelling in vitro and in vivo. In our laboratories, 4-[(N-alkyl-1,3-dioxo-1H,3H-isoindolin-5-yl)oxy]alkanoic acids and related derivatives have been synthesized and tested for ability to lower intracellular astrocytic chloride levels in an established in vitro cultured rat astrocyte model. In general, derivatives with nitrogen substituents such as relatively small alkyl groups are active at 0.1 mM and/or 0.5 mM levels whereas larger substituents such as cyclopentyl and cyclohexyl are less active. Halogen substitution on the aromatic ring did not enhance activity. Derivatives with acid side chains of four carbons demonstrated superior activity to those of two carbons.

Seasonal distribution of herbage growth from sandplain Mulga country, Charleville

Sod moisture may be adequate for rapid plant growth for prolonged periods at any time of year In the Charleville district. However, in pastures growing on mulga soils (acid, red earths), the majority of herbage is produced during the warm summer season (October 1 - March 31). Winter rams have to be well above average for herbage grown during these months to exceed 50% of annual production. The predominance of summer-growing (C4) grasses and absence of cool season grasses in the regional flora is the main reason for this pattern. The density of mulga scrub has no effect on seasonal distribution of herbage production despite major differences in botanical composition. Increased tree density reduced herbage yields but increased the protein and mineral content of this fodder

Seed coating and localized application of phosphate for improving seedling growth of grasses on acid, sandy red earths

The seedling growth of tropical grasses on acidic, sandy red earths was improved greatly by the application of small amounts of phosphate fertilizers in close proximity to the seed. Fertilizer had to be applied within 5 cm of the seed of Anthephora pubescens to have any effect. Many phosphorus sources stimulated seedling growth of Cenchrus ciliaris when applied as coatings to the fascicle (the propagule containing the grain). Water-soluble orthophosphates proved the best phosphorus sources for the purpose. Optimum rates of coating ranged up to 2 mg phosphorus per fascicle (10 mg monosodium phosphate), depending on the availability of surface soil moisture. Valuable grasses such as C. ciliaris could be introduced into millions of hectares of native pastures on infertile, sandy soils in north-eastern Australia, at reasonable cost, if a suitable commercial coating process can be developed.

Estimation of the coupling matrix elements for one-electron transfer systems

A semiempirical method, based on a correlation of ninety-nine calculated or measured values, is suggested for estimating the coupling matrix elements H(12) needed in a Landau-Zener calculation. The procedure is applicable to one-electron transfer problems, such as charge transfer and ion-ion recombination calculations, and requires only a knowledge of the crossing distance R(x), and readily available atomic properties such as ionization potentials, electron affinities, and atomic energy levels. A discussion follows explaining the possible applications and limitations of the method.