Dependent Growth Inhibition Research Articles

A Novel Lipid Nanoparticle NBF-006 Encapsulating Glutathione S-Transferase P siRNA for the Treatment of KRAS-driven Non-small Cell Lung Cancer.

Non-small cell lung cancer (NSCLC) accounts for approximately 85% of lung cancers, and KRAS mutations occur in 25-30% of NSCLC. Our approach to developing a therapeutic with the potential to target KRAS mutant NSCLC was to identify a new target involved in modulating signaling proteins in the RAS pathway. Glutathione S-Transferase P (GSTP) known as a Phase II detoxification enzyme has more recently been identified as a modulator of MAP kinase-related cell-signaling pathways. Therefore, developing a GSTP siRNA may be an effective therapeutic approach to treat KRAS mutant NSCLC. The lead drug product candidate (NBF-006) is a proprietary siRNA-based lipid nanoparticle (LNP) comprising GSTP siRNA (NDT-05-1040). Here, studies using a panel of KRAS mutant NSCLC cell lines demonstrated that NDT-05-1040 is a very potent and selective GSTP siRNA inhibitor. Our Western blot analysis showed that NDT-05-1040 effectively decreased the phosphorylation of MAPK and PI3K pathway components while upregulating apoptotic signaling cascade. Our in vivo studies revealed statistically significant higher distribution of NBF-006 to the lungs and tumor as compared to liver. In the subcutaneous and orthotopic tumor models, NBF-006 led to a statistically significant and dose dependent anti-tumor growth inhibition. Further, quantitative image analysis of PCNA and PARP staining showed that NBF-006 decreased proliferation and induced apoptosis, respectively, in tumors. Additionally, in a surgically implanted orthotopic lung tumor model, the survival rate of the NBF-006 treatment group was significantly prolonged (P <0.005) as compared to the vehicle control group. Together, these preclinical studies supported advancement of NBF-006 into clinical studies.

Abstract 677: Discovery of a first-in-class allosteric inhibitor of the small GTPase Rac1

Abstract The Rac1 signaling pathway is known to be hyperactivated in numerous solid tumors. We developed a Rac1 AlphaLISA assay that is amenable to high-throughput screening (HTS) to screen large libraries of small molecules. Based on molecular modeling of a putative allosteric binding site for several of the hits, we optimized a series of compounds that lead to RP-102124. RP-102124 engages with Rac1 in both biochemical and cellular target engagement assays. RP-102124 has greater potency than previously reported Rac1 inhibitors in biochemical assays, with potent inhibition of phenotypic characteristics of Rac signaling such as cell migration and cytoskeletal rearrangements. RP-102124 is a Racmulti inhibitor with activity against oncogenic Rac1b. RP-102124 is orally bioavailable and shows dose dependent inhibition of tumor growth in xenograft models at doses that are well-tolerated. RP-102124 is a first-in-class allosteric Racmulti inhibitor that shows promising therapeutic potential. Citation Format: Robert Silverman, Alan Cooper, Ronodip Kar, Mayuri V. Raman, Ramu Ravirala, Mubarak Hasan Shah, Sandeep Mahankali, Erik T. Goka. Discovery of a first-in-class allosteric inhibitor of the small GTPase Rac1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 677.

Catechol-Siderophore Mimics Convey Nucleic Acid Therapeutics into Bacteria.

Antibacterial resistance is a major threat for human health. There is a need for new antibacterials to stay ahead of constantly-evolving resistant bacteria. Nucleic acid therapeutics hold promise as powerful antibiotics, but issues with their delivery hamper their applicability. Here, we exploit the siderophore-mediated iron uptake pathway to efficiently transport antisense oligomers into bacteria. We appended a synthetic siderophore to antisense oligomers targeting the essential acpP gene in Escherichia coli. Siderophore-conjugated PNA and PMO antisense oligomers displayed potent antibacterial properties. Conjugates bearing a minimal siderophore consisting of a mono-catechol group showed equally effective. Targeting the lacZ transcript resulted in dose-dependent decreased β-galactosidase production, demonstrating selective protein downregulation. Applying this concept to Acinetobacter baumannii also showed concentration-dependent growth inhibition. Whole-genome sequencing of resistant mutants and competition experiments with the endogenous siderophore verified selective uptake through the siderophore-mediated iron uptake pathway. Lastly, no toxicity towards mammalian cells was found. Collectively, we demonstrate for the first time that large nucleic acid therapeutics can be efficiently transported into bacteria using synthetic siderophore mimics.

Catechol‐Siderophore Mimics Convey Nucleic Acid Therapeutics into Bacteria

AbstractAntibacterial resistance is a major threat for human health. There is a need for new antibacterials to stay ahead of constantly‐evolving resistant bacteria. Nucleic acid therapeutics hold promise as powerful antibiotics, but issues with their delivery hamper their applicability. Here, we exploit the siderophore‐mediated iron uptake pathway to efficiently transport antisense oligomers into bacteria. We appended a synthetic siderophore to antisense oligomers targeting the essential acpP gene in Escherichia coli. Siderophore‐conjugated PNA and PMO antisense oligomers displayed potent antibacterial properties. Conjugates bearing a minimal siderophore consisting of a mono‐catechol group showed equally effective. Targeting the lacZ transcript resulted in dose‐dependent decreased β‐galactosidase production, demonstrating selective protein downregulation. Applying this concept to Acinetobacter baumannii also showed concentration‐dependent growth inhibition. Whole‐genome sequencing of resistant mutants and competition experiments with the endogenous siderophore verified selective uptake through the siderophore‐mediated iron uptake pathway. Lastly, no toxicity towards mammalian cells was found. Collectively, we demonstrate for the first time that large nucleic acid therapeutics can be efficiently transported into bacteria using synthetic siderophore mimics.

Microfluidics produced ATRA-loaded PLGA NPs reduced tuberculosis burden in alveolar epithelial cells and enabled high delivered dose under simulated human breathing pattern in 3D printed head models

Tuberculosis, caused by Mycobacterium tuberculosis (Mtb), is second only to COVID-19 as the top infectious disease killer worldwide. Multi-drug resistant TB (MDR-TB) may arise because of poor patient adherence to medications due to lengthy treatment duration and side effects. Delivering novel host directed therapies (HDT), like all trans retinoic acid (ATRA) may help to improve drug regimens and reduce the incidence of MDR-TB. Local delivery of ATRA to the site of infection leads to higher bioavailability and reduced systemic side effects. ATRA is poorly soluble in water and has a short half-life in plasma. Therefore, it requires a formulation step before it can be administered in vivo. ATRA loaded PLGA nanoparticles suitable for nebulization were manufactured and optimized using a scalable nanomanufacturing microfluidics (MF) mixing approach (MF-ATRA-PLGA NPs). MF-ATRA-PLGA NPs demonstrated a dose dependent inhibition of Mtb growth in TB-infected A549 alveolar epithelial cell model while preserving cell viability. The MF-ATRA-PLGA NPs were nebulized with the Aerogen Solo vibrating mesh nebulizer, with aerosol droplet size characterized using laser diffraction and the estimated delivered dose was determined. The volume median diameter (VMD) of the MF-ATRA-PLGA NPs was 3.00 ± 0.18 μm. The inhaled dose delivered in adult and paediatric 3D printed head models under a simulated normal adult and paediatric breathing pattern was found to be 47.05 ± 3 % and 20.15 ± 3.46 % respectively. These aerosol characteristics of MF-ATRA-PLGA NPs supports its suitability for delivery to the lungs via inhalation. The data generated on the efficacy of an inhalable, scalable and regulatory friendly ATRA-PLGA NPs formulation provides a foundation on which further pre-clinical testing can be built. Overall, the results of this project are promising for future research into ATRA loaded NPs formulations as inhaled host directed therapies for TB.

Hesperidin attenuate fibrillation and cytotoxicity of human insulin: Role of secondary structure and its hydrophobicity in protein aggregation

Protein aggregation occurs when proteins are subjected to abnormal physical and chemical conditions; the subsequent aggerate can lead to multiple debilitating and deadly neurological conditions, such as Alzheimer's, Parkinson's, type II diabetes, and Huntington's disease. As such, we must further examine possible therapeutic agents such as polyphenols for possible utilization in the treatment of aggerate – born – illness. In this study, hesperidin (bioflavonoid) was examined for its anti-aggregating potential using human insulin as model protein. Our results show protein denaturing conditions (pH =2.0, Temperature 40 °C, NaCl 50 mM, agitation 1200 rpm) resulted in the formation of insulin fibrils as displayed by various spectroscopic and microscopic techniques. At 20 & 50 µM concentrations of hesperidin, aggregation of insulin decreased in a nucleation-independent manner. Far UV-CD measurement illustrated transition of α-helix to cross β-sheet during formation of amyloid. However, in the presence of hesperidin stabilization of α-helix along with concomitant decrease of β-sheet was observed. The hydrophobicity measurement suggested exposure of hydrophobic residues during fibrillation. Moreover, in the presence of hesperidin hydrophobicity was significantly dropped. Cytotoxicity of fibrillated insulin shows dose dependent inhibition of growth of SH-SY5Y cells and their protection by hesperidin. Molecular docking analysis revealed strong binding energy of 6.61 kcal mol−1 between insulin-hesperidin complex. Also, hesperidin binds to both A (Leu13, Tyr14, Glu17) and B (Phe1, Leu6, HIS10, Ala14, Glu13, Ala14, Leu17) chains of human insulin involving hydrogen and hydrophobic interactions. Conclusively, we demonstrated that hesperidin inhibited the formation of insulin amyloid and should be further exploited for insulin amyloidosis and other protein-misfolding diseases.

Abstract 2012: A novel antibody-drug conjugate platform enabling high drug-to-antibody ratios and greater payload flexibility

Abstract Historically, increasing the drug-to-antibody ratio (DAR) in an antibody-drug conjugate (ADC) significantly raises aggregation propensity as a result of the hydrophobicity of the payload. Consequently, DARs are commonly limited to 4, forcing developers to incorporate very high potency payloads to achieve the required efficacy. This, combined with chemical instability and off-target uptake, often results in dose-limiting toxicities and narrow therapeutic indexes. In this study, we used a novel and flexible multivalent linker technology to construct two ADCs targeting HER-2 with the monoclonal antibody, trastuzumab and interchain cysteine bioconjugation. One ADC incorporated monomethyl auristatin E (MMAE) as the drug payload at average DAR 16 whilst the second incorporated the camptothecin analog, SN38, as the drug payload also at average DAR 16. The ADCs were characterized by liquid chromatography-mass spectrometry (LC-MS), size-exclusion chromatography (SEC), hydrophobic interaction chromatography (HIC) and SDS-PAGE and were then tested for efficacy in a range of HER-2 positive cell lines in vitro, and tumor growth inhibition studies using NCI-N87 cells in a mouse xenograft. Both ADCs remained &amp;gt; 95% monomeric (no aggregation) and demonstrated greater chemical stability in ex-vivo serum stability studies compared to comparator ADC constructs utilizing a clinically validated linker and the same payload release chemistry. In in vitro cell killing studies, the ADCs demonstrated target-specific cell killing with the SN38 average DAR 16 ADC achieving a disproportionate 30-fold increase in IC50 (by ADC concentration) compared to a DAR 8 comparator. Dose dependent tumor growth inhibition was observed in an HER-2 positive NCI-N87 mouse xenograft model with no change in mouse body weight, and good systemic exposure. These data demonstrate our capability, using a novel multivalent linker technology, to construct ADCs with DARs considerably greater than DAR 8 which are chemically stable, shield payloads from hydrophobic interactions (no aggregation), demonstrate good in vivo exposure profiles and which are highly efficacious in vitro and in vivo. Higher DARs will permit the incorporation of lower potency and targeted small molecule payloads into ADCs which will result in targeted cancer therapeutics with wider therapeutic indexes through the delivery of greater concentrations of payload to the tumor microenvironment and lower, payload-associated, dose-limiting toxicity. Citation Format: Ludovic Juen, Adam J. Collier, Anthony W. Tolcher, Myriam M. Ouberai. A novel antibody-drug conjugate platform enabling high drug-to-antibody ratios and greater payload flexibility [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 2012.

In Vitro Antibacterial Efficacy of Cymbopogon flexuosus Essential Oil against Aeromonas hydrophila of Fish Origin and in Silico Molecular Docking of the Essential Oil Components against DNA Gyrase-B and Their Drug-Likeness.

In aquaculture, diseases caused by the Aeromonads with high antibiotic resistance are among the most common and troublesome diseases. Application of herbs is emerging as a tool in controlling these diseases. Plant extracts besides disease control, favor various physiological activities in fish. In this study, essential oil of Cymbopogon flexuosus (Poaceae family) was studied in vitro for its antibacterial efficacy against two oxytetracycline (OTC) resistant and one sensitive strains of Aeromonas hydrophila. The oil was found rich (86.93 %) in oxygenated terpenoids containing 74.15 % of citral. The oil exhibited dose dependent growth inhibition of the bacteria. Mean MIC value of the oil against the sensitive strain was recorded as 2.0 mg mL-1 whereas MBC value was recorded as 4.0 mg mL-1 . The oil was found effective against the OTC resistant isolates with the MIC and MBC values ranging from 2.67-3.33 and 4.0-6.67 mg mL-1 , respectively. In silico molecular docking of the essential oil components against DNA gyrase-B, a vital macromolecule in bacterial cell, was carried out to computationally asses the efficacy of the oil against the bacteria. Some of the components of the essential oil strongly bonded with the enzyme to inhibit its efficacy. Binding energy of some components of the oil was comparable to that of the conventional antibiotic, OTC. The identified phytochemicals exhibited favorable physicochemical and pharmacokinetic properties and satisfied the rule of five (Ro5).

In situ vaccination followed by intramuscular poly-ICLC injections for the treatment of hepatocellular carcinoma in mouse models

The efficacy of treatment for advanced hepatocellular carcinoma (HCC) has remained limited. Polyinosinic–polycytidylic acid–poly-L-lysine carboxymethylcellulose (poly-ICLC) is a synthetic double-stranded RNA that serves as a viral mimic and induces an immune response. Intratumoral (IT) poly-ICLC injections can induce an autovaccination effect and prime the immune system, whereas intramuscular (IM) injection of poly-ICLC can attract and maintain tumor-specific cytotoxic T lymphocytes in tumors. We found that IT injection of poly-ICLC upregulated the expression of CD83 and CD86 on conventional type 1 dendritic cells in tumors. Combination therapy with IT followed by IM injections of poly-ICLC significantly inhibited tumor growth and increased the tumor-infiltrating CD8+ T cells in two syngeneic mouse models of HCC. Depletion of CD8+ T cells attenuated the antitumor effect. An IFN-γ enzyme-linked immunospot of purified tumoral CD8+ T cells revealed a significant proportion of tumor-specific T cells. Finally, the sequential poly-ICLC therapy induced abscopal effects in two dual-tumor models. This study provides evidence that the sequential poly-ICLC therapy significantly increased infiltration of tumor-specific CD8+ T cells in the tumors and induced CD8+ T cell–dependent inhibition of tumor growth, as well as abscopal effects.

Potent Pre-Clinical and Early Phase Clinical Activity of EP300/CBP Bromodomain Inhibitor CCS1477 in Multiple Myeloma

CCS1477 (also known as inobrodib) is a potent and selective inhibitor of the bromodomains of EP300 and CBP, two homologous histone acetyltransferases with critical roles in cellular growth and differentiation. In preclinical analyses we find that CCS1477 induces potent growth inhibition though inducing cell cycle arrest at low nanomolar concentrations (GI50<100nM) across a panel of 12 human myeloma cell lines, including lenalidomide refractory lines. In vivo, in an OPM-2 human myeloma cell line NOD-SCID xenograft model, there was dose dependent inhibition of tumour growth, with 20mg/kg daily eliciting tumour regression and sustained inhibition of tumour growth for two weeks beyond the end of treatment. RNA sequencing of tumours recovered from mice after five days of CCS1477 treatment revealed substantial down regulation of transcription factor genes including MYB, MYC, IRF4, E2F1 and FOXM1; and GSEA showed significant enrichment among down regulated genes of gene sets associated with both MYC and E2F targets, consistent with drug-induced proliferative arrest. In the OPM-2 model, ChIP sequencing showed that EP300 binding peaks were predominantly distributed over transcription factor binding motifs for IRF, Runt, bHLH, bZIP and MYB/SANT factor classes. Within six hours of 100nM CCS1477 treatment there was a localized but significant reduction of EP300 recruitment to intronic FGFR3 sites: FGFR3 is placed under the control of the active IGH promoter in the intergenic t(4;14) in OPM-2 cells. By 48 hours, in keeping with CCS1477-induced inactivation of IRF4 (a critical regulator of plasma cell differentiation required for myeloma cell growth) there was extensive genome-wide redistribution of EP300 binding away from sites with IRF4 motifs, while sites with other motifs remained occupied. In our ongoing phase I/IIa clinical trial investigating the safety and efficacy of CCS1477 in advanced haematological malignancies (NCT04068597), we have treated four heavily pre-treated relapsed/refractory myeloma patients at the recommended phase 2 dose (35mg PO twice daily, four days a week). Of these, two exhibited objective responses with substantial reductions in serum or urinary M-protein, with one patient achieving a PR and the other exhibiting a complete remission after four months. Both patients remain on treatment as of the submission of this abstract. Treatment was well tolerated, with moderate thrombocytopaenia being an anticipated on-target side effect. Finally, we evaluated the activity of CCS1477 in an OPM-2 xenograft model in combination with existing standard of care agents in myeloma and observed additive or synergistic growth inhibitory activity with each of bortezomib, lenalidomide and vorinostat in combination with CCS1477. These encouraging data suggest strong promise for the clinical utility of CCS1477 in the treatment of multiple myeloma as monotherapy and/or in combination with standard of care agents.

Gut microbiota impairment following graphene oxide exposure is associated to physiological alterations in Xenopus laevis tadpoles

Graphene-based nanomaterials such as graphene oxide (GO) possess unique properties triggering high expectations for the development of technological applications. Thus, GO is likely to be released in aquatic ecosystems. It is essential to evaluate its ecotoxicological potential to ensure a safe use of these nanomaterials. In amphibians, previous studies highlighted X. laevis tadpole growth inhibitions together with metabolic disturbances and genotoxic effects following GO exposure. As GO is known to exert bactericidal effects whereas the gut microbiota constitutes a compartment involved in host homeostasis regulation, it is important to determine if this microbial compartment constitutes a toxicological pathway involved in known GO-induced host physiological impairments. This study investigates the potential link between gut microbial communities and host physiological alterations. For this purpose, X. laevis tadpoles were exposed during 12 days to GO. Growth rate was monitored every 2 days and genotoxicity was assessed through enumeration of micronucleated erythrocytes. Genomic DNA was also extracted from the whole intestine to quantify gut bacteria and to analyze the community composition. GO exposure led to a dose dependent growth inhibition and genotoxic effects were detected following exposure to low doses. A transient decrease of the total bacteria was noticed with a persistent shift in the gut microbiota structure in exposed animals. Genotoxic effects were associated to gut microbiota remodeling characterized by an increase of the relative abundance of Bacteroides fragilis. The growth inhibitory effects would be associated to a shift in the Firmicutes/Bacteroidetes ratio while metagenome inference suggested changes in metabolic pathways and upregulation of detoxification processes. This work indicates that the gut microbiota compartment is a biological compartment of interest as it is integrative of host physiological alterations and should be considered for ecotoxicological studies as structural or functional impairments could lead to later life host fitness loss.

756P Glypican-3 (GPC3) and NKp46 directed FLEX-NK engager antibody (CYT-303) recruits natural killer (NK) cells to tumors in a preclinical hepatocellular carcinoma (HCC) mouse model

GPC3 is an oncofetal antigen that is highly expressed in HCC while minimally expressed in adult normal tissues except placenta. CYT-303 is a multifunctional bispecific NK engager targeting NK cell activating receptor NKp46 and GPC3 expressed on tumor cells constructed with Cytovia’s Flex-NK scaffold with a fully functional Fc. Previously, we reported CYT-303 in vitro treatment of Hep3B tumor cells demonstrated cytolysis and cytokine production as well as in vivo tumor growth inhibition when combined with both PBNK and iNK cells. Here we further characterized the CYT-303 dose-response for tumor growth inhibition in vivo and its influence on NK cell distribution. CYT -303 pharmacokinetics was evaluated in tumor-bearing mice. Anti-tumor efficacy and dose response of CYT-303 in the presence of human PBNKs or iNKs was evaluated in NSG-IL15 mice bearing subcutaneous Hep3B tumors. Biodistribution of the NK cells were analyzed by flow cytometry. CYT-303 pharmacokinetics in tumor bearing mice was similar to normal mice suggesting no target mediated clearance. In the Hep3B tumor model in PBNK or iNK injected NSG-hIL-15 mice, CYT-303 showed dose dependent tumor growth inhibition compared to control hIgG1 treated mice. Consistent with CYT-303 tumor growth inhibition, increased NK cells were detected in the tumor compared to control animals. Blood NK cells in CYT-303 treated animals were significantly lower compared to IgG1 isotype control treated mice suggesting CYT-303 could facilitate NK cell trafficking from blood into the tumor. Blood AFP (alpha fetoprotein), a biomarker in HCC, decreased with CYT-303 tumor growth inhibition. Pharmacologically active CYT-303 doses were identified. CYT-303 can help recruit NK cells to the tumor site to achieve tumor growth inhibition.

Abstract 3084: Label-free, real-time live cell assays for 3D organoids embedded in Matrigel®

Abstract Organoid technologies are increasingly being used as in-vitro models of human development and disease as they exhibit structural, morphogenetic, and functional properties that recapitulate in vivo pathophysiology. To successfully use these models across a variety of research disciplines and applications, approaches that reduce variability and technology pipelines to image &amp; quantify these complex cell models are required. Here, we demonstrate simple, robust workflows for monitoring and automatically quantifying features, such as morphology, growth and death of organoids using real time live cell analysis. To quantitatively optimize and characterize organoid cultures in-vitro, mouse hepatic, intestinal and pancreatic organoids were embedded in Matrigel® domes (50% or 100%) in 24-well plates and imaged over time in an Incucyte® Live Cell System. Organoid growth, differentiation, and maturation was measured using Incucyte’ s automated Organoid Software Analysis Module, which tracks changes in size and morphology. Integrated metrics enabled objective determination of cell-type specific growth conditions and passaging regimes. To illustrate the utility of the Incucyte® Organoid Analysis Software Module to track organoid growth and death in 96-well plates, intestinal and hepatic organoid fragments were embedded in Matrigel® (50%) for 3 days prior to treatment with protein kinase inhibitor staurosporine (1 µM, STP). Vehicle treated organoids increased in size (10-fold; intestinal or 3-fold; hepatic) over time while marked reduction was observed in the presence of STP. Using label-free size and morphology metrics we could distinguish between cytotoxic and cytostatic mechanisms of action (MoA) of known chemotherapeutic compounds. STP, cisplatin (CIS, DNA synthesis inhibitor) or fluorouracil (5-FU, thymidylate synthetase inhibitor) exhibited concentration dependent inhibition of hepatic organoid growth, yielding IC50 values of 3 nM for STP, 9.7 µM for CIS and 0.78 µM for 5-FU. Whilst attenuation of size was observed across all compounds, increases in eccentricity and darkness indictive of 3D structure disruption and cell death respectively were only observed in CIS and STP-treated organoids (cytotoxic MoA). Differences between the size and morphology readouts illustrated the cytostatic mechanism of 5-FU. Use of this approach was extended to visualize and quantify CFTR function. Following forskolin stimulation, a concentration-dependent increase in intestinal organoid size was observed. In the presence of CFTR inhibitor CFTRinh-172 the maximal response was reduced by &amp;gt;50% (~150% at 10 µM) illustrating that swelling was CFTR-dependent. These data demonstrate the capability to kinetically visualize and quantify distinct organoid morphologies, assess drug-induced cellular changes label-free and illustrates the amenability of this approach across a range of disease areas. Citation Format: Tim R. Jackson, Miniver Oliver, Daniel Appledorn, Tim Dale, Kalpana Barnes. Label-free, real-time live cell assays for 3D organoids embedded in Matrigel® [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3084.

Abstract 5243: 3-Bromopyruvate in combination with radiation inhibits pancreatic cancer growth by dismantling mitochondria and ATP generation in a preclinical mouse model

Abstract 3-Bromopyruvate (3 BP) is a promising anticancer drug against pancreatic cancer. It exerts potent anticancer effects by inhibiting hexokinase II enzyme of glycolysis pathway and ATP generation in cancer cells. In present investigation we have examined the effect of 3-BromoPyruvate employing panc-2 cancer cells, and syngeneic pancreatic cancer mouse model. The clonogenic survival assay demonstrated dose dependent inhibition of cell growth, and we observed 95% cell death at 15 uM conc. Further, ATP production was severely inhibited in cancer cells treated with same concentration of 3-BP. We also observed that 3-BP in combination with low doses of irradiation was more effective in killing cancer cells than 3-BP alone. Electron microscopy revealed that 3-BromoPyruvate severely damaged mitochondrial integrity which might have severely affected ATP generation in cancer cells. We further tested 3-BromoPyruvate (2.5-10.0 mg/kg) in syngeneic panc-2 tumor mouse model and observed that 3-BP at10.0 mg/kg dose significantly reduced tumor growth (volume) about 35-40%. Immunohistochemistry (IHC) data showed that 3-BP inhibits hexokinase II (HK2) and TGFbeta1 and enhanced active caspase-3 expression in tumor tissues as compared to untreated control. The disruption of the interaction between VDAC1 and HK2 due to 3BP treatment was confirmed by CO-IP. Interestingly, 3 BP at higher dose induces caspase-3 activation in tumor derived organoid without showing any effect on normal pancreatic organoid. Altogether, the results in this study demonstrated that 3 BP could be a promising anti-tumor drug against pancreatic cancer and its efficacy could be improved in combination with radiation therapy. Citation Format: Sanjit K. Roy, Tijana Dukic, Binny Bhandary, Aneesh Acharya, Kevin J. Tu, Young H. Ko, Hem D. Shukla. 3-Bromopyruvate in combination with radiation inhibits pancreatic cancer growth by dismantling mitochondria and ATP generation in a preclinical mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5243.

Abstract 1131: Pharmacogenomic insight into targetable vulnerabilities and modifiers of response to MRTX1133 in KRASG12D-mutant models

Abstract The ability to effectively target mutated KRAS has remained elusive despite decades of research. Recently, the identification of selective KRASG12C inhibitors has provided an effective treatment option for patients harboring this particular mutation and has also provided insight toward targeting other KRAS mutants, including KRASG12D. MRTX1133 was identified via a structure-based drug design strategy as a potent, selective, and non-covalent KRASG12D inhibitor directed at the switch II binding pocket. MRTX1133 exhibited dose dependent KRAS pathway and tumor growth inhibition and demonstrated marked anti-tumor activity across a panel of models in vivo, including tumor regression &amp;gt;30% in 8 out of 11 pancreatic ductal adenocarcinoma (PDAC) models. While evaluation of MRTX1133 across a panel of cell and patient-derived xenograft models demonstrated strong single agent activity in the majority of models tested, a subset of models were less responsive. Focused sgRNA libraries targeting ~5,000 genes were tested in MRTX1133-anchored CRISPR/Cas9 screens in vitro and in vivo in PDAC and colorectal KRASG12D-mutant cell lines. Similar to what was seen in a targeted genetic screen with our selective KRASG12C inhibitor MRTX849, several genes that act either upstream or downstream of KRAS were depleted with MRTX1133 treatment which illuminate specific targetable vulnerabilities in the context of KRASG12D inhibition. sgRNAs targeting EGFR, PIK3CA, PTPN11, mTOR, and CDK2/4/6 were depleted in MRTX1133-treated (or vehicle-treated) cell lines or xenograft models, while hallmark tumor suppressor genes RB1, KEAP1, NF1 and PTEN were enriched. The enrichment of KEAP1 sgRNAs in PDAC models parallels findings with MRTX849 in preclinical models and is in line with emerging clinical data suggesting increased capacity to scavenge reactive oxygen species (ROS) may represent a mechanism of partial resistance to a non-covalent, non-electrophilic warhead-containing KRASG12D-selective inhibitor in PDAC. Treatment using small molecules targeting selected vulnerabilities in vitro and in vivo confirmed these genetic findings. Further evaluation of dependencies utilizing an integrated analysis of RNAseq data also revealed KRAS regulates and is critically dependent on pro-survival and cell cycle genes for cancer cell viability. These data lend further insight into tumor response to KRASG12D inhibition and provide key insight into the genes that mediate the mechanism of action of, as well as confer partial resistance to MRTX1133, and identify combination targets that can augment the anti-tumor effect of MRTX1133. Citation Format: Vickie Bowcut, Andrew Calinisan, David M. Briere, Lauren Hargis, Lars D. Engstrom, Jade Laguer, Darin Vanderpool, Xiaolun Wang, J David Lawson, Nicole Thomas, Robin Gunn, Christopher R. Smith, Julio Fernandez-Banet, Leo He, Adam Pavlicek, Lisa Rahbaek, Matthew A. Marx, Peter Olson, James G. Christensen, Jill Hallin. Pharmacogenomic insight into targetable vulnerabilities and modifiers of response to MRTX1133 in KRASG12D-mutant models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1131.

Abstract 5393: An oral and selective CDK12 inhibitor demonstrates robust anti-tumor activity

Abstract Background: CDK12 has emerged as an attractive cancer target due to its role in transcription and DNA damage repair regulation. In pre-clinical models, small molecule CDK12 inhibitors have demonstrated promising tumor killing effect, especially in combination with DNA damaging agents. Here we profiled new oral and selective CDK12 inhibitors. Material and methods: ADP-glo࣪ assays: inhibition of recombinant CDK12/CyclinK, CDK2/CyclinE, CDK7/CyclinH/MAT1 and CDK9/CyclinT2 was measured by assessing ADP converted from ATP via luminescent signal at Km and 20x Km ATP. Kinome screen: 1 µM of Compound A was tested in duplicate against 370 kinases at 10 µM ATP in the radiometric HotSpot™ assay. Cellular assays: p-Ser2, p-Ser5 and total RNA pol II signals were assessed 4hrs after compound treatment while ɣH2AX and BRCA1 signals were measured after 24-48hr compound treatment via Immunofluorescence (IF) assays. Cell proliferation was determined using cell titer glo after 48-72hrs compound treatment. Apoptosis was measured by annexin V/PI staining and flow cytometry analysis after 48-72hrs of treatment. Cell cycle profile was evaluated with Click-iT-EdU and FxCycle violet stain and flow cytometry analysis following 24-48hrs of treatment. Mouse xenograft: balb/c mice were implanted subcutaneously with H1048 or MDA-MB-468 cells and randomized for treatment with test drug or vehicle when tumors reached 150-200mm3. Mice were dosed BID through oral administration for 4 weeks. Combination effect of Compound A and lurbinectedin was tested in vivo. Lurbinectedin and Compound A were dosed QW and BID respectively for 28 days in H1048 CDX model. Results: A series of CDK12 inhibitors were designed and profiled in biochemical and cellular assays. A representative member of the class, Compound A, exhibited selectivity over CDK2, CDK7, and CDK9 of 46-, 27-, and 9-fold, respectively. Compound A inhibited proliferation in a panel of cell lines with EC50 in the low nanomolar range. Compound A treatment led to dose dependent apoptosis in multiple cancer cell lines and induced G2/M arrest in cancer cell lines. In vitro, combination treatment with Compound A and lurbinectedin lead to increased DNA damage accumulation, decreased homologous recombination repair, and overall enhanced antiproliferation. Dose dependent tumor growth inhibition in SCLC and TNBC CDX models was observed with Compound A treatment. Enhanced and durable antitumor effect was observed with lurbinectedin and Compound A combination compared to single agent treatment in vivo. Conclusions: We designed and profiled orally available, CDK12 selective inhibitors with potent activity as single agent in vitro and in vivo in multiple cancer models. Compound A demonstrated enhanced antitumor effect in vitro and in vivo when combined with DNA damaging agents. These data support the rationale for advancing one or more members of this class toward clinical development. Citation Format: Shan hu, David Moebius, Wojciech Dworakowski, Elliott Cooper, Derek LaPlaca, Sydney Alnemy, Phone Perera, Jason Marineau, Claudio Chuaqui, John P. Carulli, Eric Olson. An oral and selective CDK12 inhibitor demonstrates robust anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5393.

Cryptic Genes for Interbacterial Antagonism Distinguish Rickettsia Species Infecting Blacklegged Ticks From Other Rickettsia Pathogens.

BackgroundThe genus Rickettsia (Alphaproteobacteria: Rickettsiales) encompasses numerous obligate intracellular species with predominantly ciliate and arthropod hosts. Notable species are pathogens transmitted to mammals by blood-feeding arthropods. Mammalian pathogenicity evolved from basal, non-pathogenic host-associations; however, some non-pathogens are closely related to pathogens. One such species, Rickettsia buchneri, is prevalent in the blacklegged tick, Ixodes scapularis. While I. scapularis transmits several pathogens to humans, it does not transmit Rickettsia pathogens. We hypothesize that R. buchneri established a mutualism with I. scapularis, blocking tick superinfection with Rickettsia pathogens.MethodsTo improve estimates for assessing R. buchneri infection frequency in blacklegged tick populations, we used comparative genomics to identify an R. buchneri gene (REIS_1424) not present in other Rickettsia species present throughout the I. scapularis geographic range. Bioinformatic and phylogenomics approaches were employed to propose a function for the hypothetical protein (263 aa) encoded by REIS_1424.ResultsREIS_1424 has few analogs in other Rickettsiales genomes and greatest similarity to non-Proteobacteria proteins. This cohort of proteins varies greatly in size and domain composition, possessing characteristics of Recombination hotspot (Rhs) and contact dependent growth inhibition (CDI) toxins, with similarity limited to proximal C-termini (~145 aa). This domain was named CDI-like/Rhs-like C-terminal toxin (CRCT). As such proteins are often found as toxin-antidote (TA) modules, we interrogated REIS_1423 (151 aa) as a putative antidote. Indeed, REIS_1423 is similar to proteins encoded upstream of CRCT domain-containing proteins. Accordingly, we named these proteins CDI-like/Rhs-like C-terminal toxin antidotes (CRCA). R. buchneri expressed both REIS_1423 and REIS_1424 in tick cell culture, and PCR assays showed specificity for R. buchneri over other rickettsiae and utility for positive detection in three tick populations. Finally, phylogenomics analyses uncovered divergent CRCT/CRCA modules in varying states of conservation; however, only R. buchneri and related Tamurae/Ixodes Group rickettsiae carry complete TA modules.ConclusionWe hypothesize that Rickettsia CRCT/CRCA modules circulate in the Rickettsia mobile gene pool, arming rickettsiae for battle over arthropod colonization. While its functional significance remains to be tested, R. buchneri CRCT/CRCA serves as a marker to positively identify infection and begin deciphering the role this endosymbiont plays in the biology of the blacklegged tick.

Phytotoxic essential oil from black turmeric (Curcuma caesia Roxb.) rhizome: Screening, efficacy, chemical basis, uptake and mode of transport

Plant-based phytotoxins play an important role in plant-plant interaction and are of great promise for the development of bioherbicide. In this study, screening of essential oils from six different Curcuma rhizomes identified black turmeric (Curcuma caesia Roxb.) oil as an efficient growth inhibitor in wheatgrass coleoptile bioassay (IC50 57.1 µg/mL). The phytotoxic efficacy of this oil was further confirmed through the dose dependent (10.0–300.0 µg/mL) inhibition of germination, coleoptile and radicle growth of wheatgrass seeds in water medium (IC50 176.7, 90.6 and 93.0 µg/mL respectively) and the pre-germinated seeds in agar medium. Activity-guided fractionation and purification of the crude oil identified curzerenone, a major furanosesquiterpene in this oil as the most active phytotoxin (IC50 13.0 µg/mL in coleoptile bioassay; 188.3, 34.7 and 36.7 µg/mL respectively in water medium). Structure-activity relationship study indicated the importance of all the functional groups for its phytotoxicity. A significant contribution by the oxygenated monoterpenes towards oil phytotoxicity was also evidenced. Though inhibitory efficacy of the oil was comparatively weak in soil, a profound activity through aerial diffusion was observed against germination and/or growth of fresh and pre-germinated wheatgrass seeds (IC50 1.4–6.2 mg/L air). The study also confirmed the uptake of active phytotoxins with no detectable transformation by the seeds in water and their persistence in the soil for at least one and half months. Further, its applicability was demonstrated through an efficient post-emergence growth inhibition (IC50 37.0–81.4 µg/mL) of bermudagrass weed in water and agar medium.

Abstract P5-17-01: Targeting Acetyl-CoA carboxylase in pre-clinical breast cancer models

Abstract Background: Cancer cells and normal cells of the same lineage differ in their metabolism. We previously described large scale shifts in isoenzyme distribution between matching cancer and normal tissues and identified Acetyl-coA carboxylase (ACC1/ACACA) as a cancer dominant enzyme that is overexpressed in multiple cancer types. ACC1 catalyzes the initial rate-limiting step in de novo fatty acid synthesis, the conversion of acetyl-CoA to malonyl-CoA. Gene knock-out experiments demonstrated that this enzyme is essential for cancer growth. In this study, we evaluated the in vitro and in vivo efficacy of a small molecule ACC inhibitor, PF05175157 as a potential anticancer drug. This drug has been tested in clinical trials for diabetes, but development was discontinued due to grade 2 thrombocytopenia.Methods: We performed in vitro cytotoxicity assays in 15 breast cancer cell lines and in normal mammary epithelial HMEC cells, examined effect on apoptosis and cell cycle progression, and tested for synergy with alpelisib, docetaxel, doxorubicin, everolimus, iniparib, neratinib and TEPP46 (PKM2 and PKLR activator). We next assessed in vivo single agent activity in a triple negative patient derived (PDX) model (J000102184) in NSGTM mice and in MDAMB468 xenografts implanted into Rag2/IL2RG double knockout mice. We performed RNA sequencing and metabolomic profiling of cells treated with PF05175157 to study metabolic and transcriptomic effects of the drug. Results: PF05175157 induced time and dose dependent growth inhibition in all but 1 of the 15 cancer cell lines. The estimated EC50 after 72h exposure ranged from 0.95 to 76 μg/mL in T47D and BT549 cells, respectively (Cmax of 20 μg/mL can be achieved in human serum). There was no significant inhibitory effect on HMEC cells. In cancer cell lines, the % of apoptotic cells increased from 4% to 8% in BT474 and from 7.7% to 17.8% in MDMBA468 cells upon treatment with the compound, and there was a trend towards G2/M cell cycle arrest in both cell lines after 72 hours of exposure (10μg/mL). In drug combination experiments, PF05175157 added to iniparib, or to the PKM2 activator, TEPP46, decreased cell viability compared to single agent therapies in several cell lines. PF05175157 significantly delayed tumor growth compared to vehicle, when administered orally (20mg/kg gavage BID) in a TNBC PDX model (median tumor volume after 33 days: 334.1 mm3 in PF05175157-treated vs. 490.5 mm3 in methylcellulose-treated mice; p=3.39e-7) and intraperitoneally (20 mg/kg in DMSO) in an MDAMB468 xenograft model (median tumor volume after 40 days: 244.5 mm3 in PF05175157-treated vs. 303.3 mm3 in DMSO-treated mice; p&amp;lt;0.05). Transcriptomic and metabolic profiling of MDAMB468 and BT474 cells treated with 10 ug/ml PF05175157 for 6 and 24 hours revealed activation of immune signaling, epigenetic regulation and DNA damage repair pathways along with down-regulation of a broad range of metabolic pathways. Conclusions: The small molecule ACC inhibitor, PF05175157, has significant single agent in vitro and in vivo growth inhibitory effect on a range of breast cancer cell lines at concentrations that can be achieved in human serum. It showed synergy with iniparib and another metabolic inhibitor (TEPP46). Targeting de novo fatty acid synthesis by inhibiting ACC is a promising therapeutic strategy. Citation Format: Julia Foldi, Michal Marczyk, Vignesh Gunasekharan, Tao Qing, Raghav Sehgal, Naing Lin Shan, Viswanathan Muthusamy, Sheila Umlau, Yulia V. Surovtseva, Richard Kibbey, Lajos Pusztai. Targeting Acetyl-CoA carboxylase in pre-clinical breast cancer models [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-17-01.

Chemical Characterization, Antimicrobial, Antiproliferative and Antioxidant Activities of the Essential Oil of Monarda citriodora Growing in Kashmir

Objectives: The main aim of this research was to evaluate phytochemicals, antimicrobial, antiproliferative and antioxidant Activities of the essential Oil of Monarda citriodora growing in Kashmir (India). Materials and Methods: Essential oil obtained by hydrodistillation from the flowers of Monarda citriodora was analysed by a combination of capillary gas chromatographymass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC-FID) techniques. The essential oil was evaluated for its antimicrobial and antioxidant potential. Antimicrobial activity was evaluated against two fungal and seven bacterial strains. The antiproliferative efficacy was evaluated by Sulphorhodamine-B assay. Results: A total of 13 components were identified constituting 99.4% of the total oil composition. Thymol (79.7%), P-cymene (7.7%), Tricyclene (4.5%) and carvacrol (3.0%) were found to be the major components. The oil composition was totally dominated by oxygenated monoterpenes constituting 83.2%. Additionally, potent and broad-spectrum of antimicrobial activities were shown by the essential oil. In vitro cytotoxic studies revealed concentration dependent growth inhibition of all target cancer cell lines in the 10-100 μg/ml dilution range, with IC50 values of 24.2μg/ml (THP-1), 55.5μg/ml (A-549), 31μg/ml (HEP-2) and 37.5μg/ml (Caco-2). Antioxidant studies of the essential oil evaluated by two complementary assays viz DPPH and hydroxyl radical assays confirmed that the oil exhibited potent and dose-dependent inhibition of the DPPH and hydroxyl radicals with IC50 values of 19.3μg/ml and 39.2μg/ml respectively. Conclusion: We concluded that the essential of Monarda citriodora growing in Kashmir is rich in chemical composition and possess significant antimicrobial, antioxidant and antiproliferative activities.