Generate Dose Response Research Articles

Anti‐cytokine antibodies attenuated neuroglial degeneration under hypoxic stress

Aims/Purpose: Hypoxia is a vital cause of neurodegenerative diseases such as glaucoma and retinal ischemia. We investigated the potential neuroprotective effects of anti‐cytokine antibodies against hypoxic damage.Methods: An in vitro hypoxia model was established using cobalt chloride (CoCl2) stimulation in microglial cells (BV‐2). Immunofluorescence staining was performed to detect the expression markers of different microglial phenotypes in BV‐2. Different concentrations of CoCl2 (0–150 μM) were tested to generate dose–response curves. Following exposure to CoCl2 at an approximate IC50 of 0.1 mM, BV‐2 were treated with anti‐tumour necrosis factor‐alpha (anti‐TNF‐α) or anti‐ interleukin‐1 beta (anti‐IL‐1β) antibodies for 24 h. Cell viability was determined by MTS assay. Proteome changes in BV‐2 were analysed with the mass spectrometry‐based proteomics approach.Results: Immunocytochemistry revealed the expression of M1 marker consisting CD68 and M2 marker CD206 in the BV‐2 cells. Hypoxia induced by mimetic CoCl2 led to a concentration‐dependent viability impairment in BV‐2 and cells treated with 0.1 mM CoCl2 for 24 h showed decreased viability of ~46%‐ 50%. Interestingly, the application of anti‐TNF‐α (2ug/ml) and anti‐IL‐1β (4ug/ml) antibodies significantly improved the BV‐2 cell viability to 80% (p < 0.0001) and 76% (p < 0.0001), respectively. Proteomics and bioinformatics analyses of the differentially expressed proteins revealed that CoCl2 induced proteome alterations involved in mitochondrial dysfunction signalling pathway (p = 1.10 × 10−3), which were eliminated by the treatment with both anti‐TNF‐α and anti‐IL‐1β. Besides, CoCl2‐induced activation of endoplasmic reticulum (ER) stress response (p = 3.33 × 10−9) was alleviated by anti‐IL‐1β and anti‐TNF‐α treatment (p = 1.7 × 10−7 and p = 8.82 × 10−7, respectively). Particularly, anti‐TNF‐α antibody significantly downregulated proteins involved in apoptosis (p = 1.58 × 10−10). Anti‐IL‐1β induced Nrf2‐mediated antioxidant response and exerts protection against oxidative stress (p = 1.00 × 10−6).Conclusions: Antibodies targeting cytokines provide neuroprotective effects on microglial cells from hypoxic stress. These findings demonstrated the potential use of anti‐cytokines in the treatment of neurodegenerative diseases.

Abstract B071: Evaluating the synergy between enzalutamide and SRC kinase inhibitors against castration-resistant prostate cancer

Abstract Prostate Cancer (PCa) remains the most diagnosed non-skin cancer amongst the American male population. Treatment for localized prostate cancer consists of Androgen Deprivation Therapies (ADTs), which inhibit the full-length androgen receptor (AR-FL). Though initially effective, a subset of patients will develop resistance to ADTs and the tumors will transition to Castration-Resistant Prostate Cancer (CRPC). Second-generation hormonal therapies such as abiraterone acetate and enzalutamide (Enza) are typically given to men with CRPC. However, these treatments are not curative and typically prolong survival by a few months, prompting investigators to understand the mechanisms of resistance corresponding to CRPC. Several resistance mechanisms contribute to this lack of efficacy of these therapies such as the emergence of AR mutations, AR amplification, AR splice variants (AR-Vs) and in some cases increased kinase signaling. In this study, we evaluated whether inhibition of a hyperactive tyrosine kinase in CRPC, SRC, synergizes with enzalutamide or chemotherapy in several prostate cancer cell line models expressing variable AR isoforms. Five cell lines were chosen: DU145 (AR-negative), AD-1 (AR-FL positive), R1-D567 (AR-V positive), LNCaP95 and 22Rv1 (AR-FL/AR-V positive), all of which express SRC protein. We then administered enzalutamide, the SRC family kinase inhibitor saracatinib (Sara), or docetaxel (DTX) at varying doses to each cell line to generate dose response curves and IC50 values. Each drug’s IC50 was used for combination therapy studies. To determine synergy, we implemented the Bliss Independence equation and the Combination Index Equation via Chou-Talalay method. To define the mechanism of synergy, we used western blotting and immunofluorescence to measure molecular changes (protein and mRNA) in our cell lines. In our CRPC cell lines, LNCaP95 and 22rv1, we observed robust synergy for Enza plus Sara. Interestingly, we found a lack of synergy for DTX plus Sara, in 22rv1 cells. In this cell line, we also found that Enza and Sara individually induced a greater amount of DNA damage when compared to DTX. We observed higher activation of Caspase 3/7 and cleaved PARP expression when Enza plus Sara was administered. We also observed a significant decrease in AR Y534phosphorylation, a key SRC substrate residue, on both AR-FL and AR-V with a concomitant decrease in AR-V protein expression after saracatinib administration. In addition, we observed a decrease in mRNA expression of AR target genes, TMPRSS2 and KLK3. Overall, our results suggest that SRC inhibition is a potential therapeutic strategy to be used in combination with potent AR targeting agents in the treatment of CRPC, due to its effects on AR/AR-Vs at the protein and mRNA level. By elucidating this synergy, we provide pre-clinical data that suggests combining SRC kinase inhibitors with enzalutamide in certain patients with AR-Vs. Citation Format: Ralph E. White, Victor Tan, Maxwell Bannister, Hai Dang Nguyen, Justin M. Drake. Evaluating the synergy between enzalutamide and SRC kinase inhibitors against castration-resistant prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr B071.

Abstract 192: A novel and rapid patient-derived organoid breast cancer platform for precision medicine

Abstract An increasing number of studies performing correlative drug screens on patient-derived organoids (PDO) are revealing enormous potential for these models in predicting patient response to therapy. Despite this, their future use in a clinical setting is hindered by intrinsic limitations of PDO models, namely low success rates in establishing growing cell cultures from tumor tissue samples and long return times for drug response data that fall outside timescales of clinical actionability. To address these limitations, we leveraged technological advances in emulsion-based microfluidics and droplet generators to develop MicroOrganoSpheres (MOS) - microscale environments containing tumorspheres that retain structural, cellular, and genetic properties of an individual patient’s diseased tissue. Here, we focused on generating MOS from breast cancer tissue biopsies and resections across different subtypes of breast cancer. We established over 30 unique patients’ breast MOS samples at an average of 80% success, with the majority of these samples being hormone receptor positive (ER+/PR+) - the most clinically lethal and challenging subtype to establish. We evaluated MOS dose-responses across several first line standard of care chemotherapies for breast cancer. For this, we created a semi-automated workflow paired with high-content imaging for quantifying dose responses and tracking longitudinal cell dynamics during dosing. We generated dose response data for MOS samples, being able to move from primary tissue samples to MOS to drug dosing data within a clinically relevant timescale of 2-3 weeks. We conclude that our platform demonstrates the feasibility of 1) efficiently establishing MOS from breast cancer patient tumor samples from different subtypes and 2) performing drug dosing studies on these samples with improved turnaround times that enable clinical actionability for the patient. Together, these findings provide a foundation for evaluating this technology as a diagnostic tool in future clinical settings. Citation Format: David M. Graham, Gabrielle Rupprecht, Eric D. Bankaitis, Jeremy M. Force, Wylie Watlington, Steven W. Metzger, Xiling Shen, David Hsu. A novel and rapid patient-derived organoid breast cancer platform for precision medicine [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 192.

Abstract 4976: Preclinical characterization of BGI-9004, a covalent TEAD inhibitor with exceptional anti-cancer activity and combination potential

Abstract Pharmacological inhibitors of TEAD transcription factors have emerged as a promising novel class of anti-cancer agents. TEAD inhibitors disrupt oncogenic YAP/TAZ signaling, resulting in cell cycle arrest and cell death in susceptible cancers. In preclinical models, cancer cell lines with alterations in the Hippo signaling pathway, such as mutations or loss of NF2 or LATS, are particularly sensitive to inhibition of TEAD signaling. In addition, YAP/TAZ-TEAD signaling is thought to play a role in resistance to several targeted therapies, such as EGFR inhibitors and MEK inhibitors. BGI-9004 is a covalent inhibitor of TEAD1-4 with low nanomolar potency in a TEAD reporter cell line and anti-cancer activity in vitro and in vivo. In the NF2-deficient NCI-H226 and the NF2-wildtype, LATS-mutant MST-O211H mesothelioma xenograft models, BGI-9004 treatment resulted in sustained tumor regressions over a 28d treatment course. Anti-cancer activity was accompanied by significant inhibition of TEAD-mediated transcription in BGI-9004-treated tumors, and no adverse effects on the body weight of treated mice were observed. Moreover, proteome-wide protein binding of BGI-9004 was assessed by Isobaric Mass Tagged Affinity Characterization (IMTACTM), which confirmed its high selectivity for TEAD. In line with this, BGI-9004 had a clean profile in a panel of protein targets that present potential safety liabilities (CEREP safety panel). These findings prompted us to explore the combination potential of BGI-9004 with other targeted therapies, including inhibitors of EGFR, MEK and mutant KRASG12C. Here, we found that BGI-9004 potentiated the effect of other targeted therapies. In particular, we generated dose response matrices for BGI-9004 and inhibitors of KRASG12C and KRASG12D in several KRAS-mutant cell lines, including three lung cancer cell lines, and demonstrated synergy for the combination. These results suggest that inhibition of YAP/TAZ-TEAD signaling may improve the efficacy of KRAS-targeted therapy. Taken together, the covalent TEAD inhibitor BGI-9004 has demonstrated promising activity both as a single agent and in combination with other targeted agents, a favorable pharmacokinetic profile and high target selectivity in preclinical models, supporting its evaluation as a novel anti-cancer agent in clinical trials. Citation Format: Shirley Guo, Shashank Shrishrimal, Jason Cui, Guoqing Wang, Vivian Zhang, Ning Deng, Iris Dong, Anna Chen, Steve Luo, David Sperandio, Ping Cao, Wolf R. Wiedemeyer. Preclinical characterization of BGI-9004, a covalent TEAD inhibitor with exceptional anti-cancer activity and combination potential. [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 4976.

High-Efficiency Multi-Drug Functional Profiling in a Microfluidic Device Towards Personalized Predictions in Pediatric Leukemia

Treatment of pediatric acute lymphoblastic leukemia (ALL) has seen dramatic improvements over the last several decades, leading to overall survival rates of over 85%. However, for patients with relapsed/refractory disease, achieving complete remission remains extremely challenging. Improving treatment outcomes for these patients will require increasingly personalized treatment strategies that make use of functional screens in addition to molecular profiling technologies for treatment selection. Given the past success of combination chemotherapy in cancer treatment and recent promise for newly developed targeted agents, functional assays that are able to evaluate patient response to combinations of therapies will likely be most effective in identifying clinically actionable treatment protocols. Moreover, assays that can achieve this with minimal patient sample and reduced experimental workload will have the greatest potential for clinical translation and integration into clinical workflows. To that end, this work aims to develop a microfluidic assay to directly test candidate combinations of therapeutics in patient derived ALL cells. We aim for this to serve as a more effective way to screen for drug combination response and higher order interactions relative to standard wellplate formats. Once validated, this assay can be used to identify biomarkers of response to standard and experimental combination regimens in pediatric ALL, and ultimately, could be used to prospectively guide therapy in newly diagnosed patients. The developed device achieves this by enabling simultaneous exposure to 3 superimposed small molecule drug gradients across a 3D culture of leukemia cells such that each location in the device comprises a unique combination of all 3 drugs within a simplex (Fig 1A). Single cell drug concentration exposure is determined from experimentally validated steady state computational fluid dynamics (CFD) model predictions, and single cell viability is analyzed via Calcein (live), PI (dead) and Hoechst (nuclear) staining following 48 hours of treatment. Using this system, we then develop a novel experimental and computational framework for evaluating drug combination efficacy and synergy across the full range of combination ratios captured in our device. Specifically, we evaluate response across multiple devices at optimally spaced dose levels, increasing coverage of the 3-drug combination space and allowing for custom implementation of established synergy models. This enables synergy assessment in a continuous gradient of drug combination ratios, as opposed to the discrete combination ratios commonly evaluated in standard assays, and may further improve detection of drug synergy and identification of the most potent and efficacious combination ratios. To demonstrate this, we analyze response to a combination of daunorubicin, vincristine, and nelarabine in Jurkats, a T-ALL cell line, across 7 different devices at 7 different dose levels (Fig 1B). We quantify viability as a function of concentration across each device and each dose level, and generate dose response curves at distinct zones within the device. Specifically, we generate dose response curves in zones dominated by daunorubicin, vincristine, and nelarabine alone and find half maximal effective concentration values (EC50 values) similar to those reported in literature. We further evaluate response at varying ratios of each 2-drug combination, and generate dose response curves as shown in Fig 1B. Analyzing the 2-drug combination dose responses relative to single-drug dose responses allows for quantification of 2-drug combination synergy based on Loewe and DiaMOND synergy models, and future work will extend our developed method to analyze emergent 3-drug combination synergy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Dosimetric and TL investigation of natural and heat-treated Pakistani Onyx at high beta doses

Extensive Thermoluminescence (TL) glow curve analysis of natural (S1) and heat-treated (S4) Pakistani Onyx marble is reported exploring an alternative natural radiation dosimeter. TL curves for β-doses ranging from 0.5 Gy to 10 kGy are measured within the temperature range of 25–500 °C and analyzed to generate dose response curves (DRCs). Single saturation exponential function and DRCs are used to evaluate the characteristic dose value and the intensity saturation level. The glow peak repeatability test identifies unstable TL trapping sites in S1 at high temperatures (≥350 °C). Fading analysis of S4 shows that a major signal loss (40%) occurs within 24 h because of low temperature (<130 °C) peaks. After irradiation, time-temperature investigations are performed to optimize the pre-heat condition and remove fast fading peaks. The kinetic parameters are estimated using the TM-Tstop technique and the curve deconvolution method. The post-irradiation preheat at 100 °C for 10 s and TL data collection up to 400 °C with a heating rate of 5 °C/s is concluded as appropriate measurement condition to perform dosimetric studies of S4. The quantitative analysis of S4 dose response showed a linear behavior from 2 to 20 Gy, supra-linear from 20 to 5000 Gy, and sublinear response after 5–10 kGy. The minimum detectable dose (MDD) and percentage coefficient of variation (COV) of repeatability for S4 are 236 ± 8 mGy and 1.53% respectively. The study concludes that Pakistani Onyx marble, with thermal treatment of 500 °C for 1 h, can be a radiation dosimeter for high dose applications.

Macrophage bioassay standardization to assess the anti-inflammatory activity of mesenchymal stromal cell-derived small extracellular vesicles

Background aimsOwing to the lack of biological assays, determining the biological activity of extracellular vesicles has proven difficult. Here the authors standardized an in vitro assay to assess the anti-inflammatory activity of mesenchymal stromal cell-derived small extracellular vesicles (MSC-sEVs) based on their ability to prevent acquisition of the M1 phenotype in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Induction of tumor necrosis factor alpha, IL-1β, IL-6 and inducible nitric oxide synthase (iNOS) characterizes the M1 phenotype. Nitric oxide released by iNOS turns into nitrite, which can be easily quantitated in culture media by Griess reaction. MethodsThe authors first tested different assay conditions in 96-well plates, including two seeding densities (2 × 104 cells/well and 4 × 104 cells/well), four LPS doses (1 ng/mL, 10 ng/mL, 100 ng/mL and 1000 ng/mL) and two time points (16 h and 24 h), in order to determine the best set-up to accurately measure nitrite concentration as an index of M1 macrophage polarization. ResultsThe authors found that seeding 2 × 104 cells/well and stimulating with 10 ng/mL LPS for 16 h allowed the inhibition of nitrite production by 60% with the use of dexamethasone. Using these established conditions, the authors were able to test different MSC-sEV preparations and generate dose–response curves. Moreover, the authors fully analytically validated assay performance and fulfilled cross-validation against other M1 markers. ConclusionsThe authors standardized a quick, cheap and reproducible in vitro macrophage assay that allows for the evaluation and estimation of the anti-inflammatory activity of MSC-sEVs.

Label-Free Optical Detection of Pathogenic Bacteria and Fungi at Extremely Low Cell Densities for Rapid Antibiotic Susceptibility Testing.

Antibiotic resistance is a rapidly expanding public health problem across the globe leading to prolonged hospital admissions, increased morbidity and mortality, and associated high healthcare costs. Effective treatment of bacterial infections requires timely and correct antibiotic administration to the patients which relies on rapid phenotyping of disease-causing bacteria. Currently, antibiotic susceptibility tests can take several days and as a result, indiscriminate antibiotic use has exacerbated the evolution and spread of antibiotic resistance in clinical and community settings. In order to address this problem, we have developed a novel optical apparatus that we called RUSD (Rapid Ultra-Sensitive Detection). RUSD is built around a hollow silica fiber and utilizes bacterial cells as spatial light modulators. This generates a highly sensitive modulation transfer function due to the narrow reflectivity angle in the fiber-media interface. We leveraged the RUSD technology to allow for robust bacterial and fungal detection. RUSD can now detect pathogenic cell densities in a large dynamic window (OD600 from ∼10−7 to 10−1). Finally, we can generate dose response curves for various pathogens and antimicrobial compounds within one to three hours by using RUSD. Our antibiotic- susceptibility testing (AST) assay that we call iFAST (in-Fiber-Antibiotic-Susceptibility-Testing) is fast, highly sensitive, and does not change the existing workflow in clinical settings as it is compatible with FDA-approved AST. Thus, RUSD platform is a viable tool that will expedite decision-making process in the treatment of infectious diseases and positively impact the antibiotic resistance problem in the long term by minimizing the use of ineffective antibiotics.

Estimation of Tolerable Daily Intake (TDI) for Immunological Effects of Aflatoxin.

Aflatoxins are toxic chemicals produced by the fungi Aspergillus flavus and Aspergillus parasiticus. In warm climates, these fungi frequently contaminate crops such as maize, peanuts, tree nuts, and sunflower seeds. In many tropical and subtropical regions of the world, populations are coexposed to dietary aflatoxin and multiple infectious pathogens in food, water, and the environment. There is increasing evidence that aflatoxin compromises the immune system, which could increase infectious disease risk in vulnerable populations. Our aim was to conduct a dose-response assessment on a noncarcinogenic endpoint of aflatoxin: immunotoxicological effects. We sought to determine a noncarcinogenic tolerable daily intake (TDI) of aflatoxin, based on the existing data surrounding aflatoxin and biomarkers of immune suppression. To conduct the dose response assessment, mammalian studies were assessed for appropriateness of doses (relevant to potential human exposures) as well as goodness of data, and two appropriate mouse studies that examined decreases in leukocyte counts were selected to generate dose response curves. From these, we determined benchmark dose lower confidence limits (BMDL) as points of departure to estimate a range of TDIs for aflatoxin-related immune impairment: 0.017-0.082 μg/kg bw/day. As aflatoxin is a genotoxic carcinogen, and regulations concerning its presence in food have largely focused on its carcinogenic effects, international risk assessment bodies such as the Joint Expert Committee on Food Additives (JECFA) have never established a TDI for aflatoxin. Our work highlights the importance of the noncarcinogenic effects of aflatoxin that may have broader public health impacts, to inform regulatory standard-setting.

Co-Occurring Mutation Clusters Predict Drug Sensitivity in Acute Myeloid Leukemia

Background The molecular origin of cancer drug resistance is not apparent for most cases of acute myeloid leukemia (AML). Clonal evolution appears to be associated with increasing drug resistance. We sought to determine whether the mutation patterns are associated with drug susceptibility in AML. Methods Seventy-two patient blood or marrow samples were enriched for CD34+ blasts by immunomagnetic bead selection. High throughput drug sensitivity screens were performed for 223 drugs after a 72-hour exposure to 8-12 customized drug concentrations (within the range of 5pM to 100µM) of each drug spanning 4-5 logs. Post exposure viability was determined using CellTiter Glo luminescent reagent. XLFit was used to analyze the data and generate dose response curves based on a standard 4-parameter logistic fit. Mutation analysis was performed by MyAML™ utilizing next generation sequencing (NGS) to analyze the 3' and 5' UTRs and exonic regions of 194 AML-associated genes and genomic breakpoints. Co-mutation and mutual exclusivity scores of gene aberrations were computed using three different statistical methods on three large publicly available datasets: 1) TCGA-AML, 2) BeatAML, and 3) data from 1540 patients (Moritz Gerstung, et al., Nat Genet. 2017). The scores for each co-mutation or mutually exclusive gene pair were then logarithmically transformed from the aggregated p-value using a robust rank aggregation method and used to construct a graph from which communities of co-mutated genes could be detected, resulting in higher mutual exclusivity between modules and higher co-occurrence within modules. Results We identified five main groups of co-mutations, including the following: 1) RUNX1 group, 2) CEBPA group, 3) NPM1 group, 4) TP53 group, and 5) RAS group (see Fig 1A). The co-mutation community in the RUNX1 group is featured with transcriptional dysregulation (RUNX1, ASXL1 and EZH2), and dysregulation in splicing (U2AF1, SRSF2 or SF3B1). The TP53 and CEBPA groups exhibit transcriptional dysregulation, and transcription factor alterations. The NPM1 and RAS groups exhibit signaling alteration, particularly the Ras/MAPK signaling pathway. Among each co-mutation community, the variant allele frequencies (VAFs) exhibited differences for specific mutations. For example, in the NPM1 group, FLT3 exhibits the lowest VAF, followed by NPM1 while DNMT3A shows the highest VAF. The five co-mutation groups are associated with different overall survival, including better survival for the CEBPA group and poorer survival for the TP53 group. Within each co-mutation group, specific associations with overall survival were detected, including better survival for NPM1-RAD21 co-mutated vs. wild type (WT), better survival for WT vs. ASXL1-RUNX1 co-mutated, worse survival for DNMT3A-FLT3 co-mutated vs. WT, and others. We also found that the co-mutation clusters were different between the de novo and relapse groups. Most importantly, we found significant correlations with drug sensitivity for the different co-occurring mutation groups. Cells from patients with mutations in the NPM1 co-mutation group show higher sensitivity to most of the drugs, including the tyrosine kinases inhibitors and PI3K-AKT-MTOR inhibitors. Cells from patients with mutations in the RAS cluster exhibited sensitivity to MEK inhibitors (Fig 1B), while cells from patients with mutations in the TP53 cluster show resistance to many drugs, including the MDM2 inhibitor AMG232 (Fig 1C). By mapping the mutated genes and drug targets into signaling pathways, we found that mutations in downstream signaling of the drug target exhibited resistance, while mutations in upstream signaling conferred higher sensitivity. We also constructed drug sensitivity prediction models based on the co-mutation groups. Conclusion We detected co-mutation groups through integrative analysis of large publicly available AML data sets. Patients with mutations in different groups of genes show different overall survival, while cells from patients with mutations in different co-mutation groups show different drug sensitivity. The co-mutation groups may not only reflect the clonal evolution history of AML, but also serve as important features for drug sensitivity prediction. Disclosures Carson: Invivoscribe, Inc: Current Employment. Patay:Invivoscribe, Inc: Current Employment. Becker:Cardiff Oncology: Research Funding; Novartis: Research Funding; SecuraBio: Research Funding; JW Pharmaceutical: Research Funding; Glycomimetics: Research Funding; Abbvie: Research Funding; Bristol Myers Squibb: Research Funding; Pfizer: Research Funding; Invivoscribe: Research Funding; Accordant Health Services/Caremark: Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: There are ~200 drugs on the screening panel, and many would be off label for acute myeloid leukemia.

Abstract 4139: Investigations of drug synergy reveal promising efficacy of EphA2 inhibition combined with CDK inhibition in triple-negative breast cancer

Abstract Triple-negative breast cancer (TNBC) is an aggressive malignancy with poor prognosis relative to other breast cancers. Due to its lack of expression of commonly targeted cell surface markers and hormone receptors, there is a dearth of precision treatment options for this malignancy, with chemotherapy and radiation therapy remaining the major mainstays of care. Our group has previously reported that the receptor tyrosine kinase EphA2 is enriched in the basal-like/triple-negative breast cancer subtype and that this expression is associated with reduced recurrence-free survival. Furthermore, genetic knockdown or inhibition of EphA2 with the small molecule ALW-II-41-27 (ALW) reduces cancer cell growth in vitro and in vivo. In these studies, we sought to investigate whether the antitumor properties of ALW can be augmented by addition of other compounds to further reduce cancer cell growth and induce apoptosis. To this end, TNBC lines MDA-MB-231, BT-549, HCC1395, and HCC1187 were seeded in 96-well plates and exposed to ALW alone or in combination with chemotherapeutic agents doxorubicin and paclitaxel, CDK inhibitor SCH-727965, and MCL-1 inhibitor S63845 and cell viability assessed by MTT assay at 48 hours. While there was no significant reduction in viability for cells treated with ALW plus chemotherapy and no consistent improvement with addition of S63845 across cell lines, the combination of ALW with SCH-727965 performed significantly better than either drug alone (p &amp;lt; 0.05) in HCC1395 and BT-549 cells. To evaluate drug synergy, cells of all lines above were exposed to variable concentrations of SCH-727965, ALW, and the combination in a fixed ratio of their respective IC50 values to generate dose response curves, and these data analyzed via CompuSyn software. Combination indices (CI) were &amp;lt;1 for the majority of conditions across all cell lines, supporting synergistic interaction. Effects were most pronounced in HCC1395 cells with average CI 0.82. Furthermore, TUNEL assays show that addition of SCH-727965 to ALW significantly increases the induction of apoptosis by HCC1395 and HCC1187 cells. These preclinical studies demonstrate that combination of ALW and SCH-727965 potently reduces TNBC cell growth and promotes cell death, representing promising early data on the effects of EphA2 inhibition as part of a combination targeted therapeutic approach for triple-negative breast cancer. Citation Format: Kalin L. Wilson, Dana M. Brantley-Sieders. Investigations of drug synergy reveal promising efficacy of EphA2 inhibition combined with CDK inhibition in triple-negative breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4139.

Abstract 41: A novel high-throughput microfluidic drug screening platform using pancreatic ductal adenocarcinoma derived organoids

Abstract Pancreatic cancer is one of the deadliest tumors due to the limited treatment options and late diagnosis. Here, we describe a novel high throughput drug screening platform combining a microfluidic based 3D-culture plate, and the recently described pancreatic ductal adenocarcinoma (PDAC) derived organoids. The microfluidic plate is a high throughput microfluidic 3D cell culture platform, supporting physiologically relevant models with a minimal requirement of cell material and enabling a wide range of flow and co-culture options (e.g. with blood vessels). Organoids were derived from human PDAC xenografts and seeded in the microfluidic plate. The low amount of tissue material required (4000 cells per chip) and the high number of replicates on one plate (n=96 on a standard microtiter format plate) renders the microfluidic plate an efficient and cost-effective platform for drug screening and toxicity assays on complex, 3D models. Organoids were exposed to various chemotherapeutic drugs for 72 hours. The viability of the organoids before and after drug treatment is monitored with standard viability assays and subsequently used to generate dose response curves. In conclusion, we showed that the microfluidic plate can be used for high throughput drug screening assays and toxicity screening, and demonstrated its compatibility with human pancreatic PDAC derived organoids. Citation Format: Bart Kramer, Wijnand van Paassen, Luuk de Haan, Henriette Lanz, Jos Joore. A novel high-throughput microfluidic drug screening platform using pancreatic ductal adenocarcinoma derived organoids [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 41.

Abstract 3337: A racially/ethnically diverse 3D PDX model of prostate cancer

Abstract Prostate cancer (PCa) incidence and mortality rates in African American men are double that of any other race/ethnicity in the United States. Thorough understanding of the biological factors that contribute to this long-standing cancer health disparity (CHD) is required to improve the major public health concern and close this gap. However, few models exist that can compare racially-diverse specimens directly and provide a platform for dissecting the impact of ancestry-dependent factors on disease pathway selection and drug susceptibility. Both the conventional 2D culture of clonal human cell lines and the purely rodent-based in vivo models fail to reflect the heterogeneity of human tumors, often leading to inaccurate prediction of in vivo tumor response in patients, and confounding researchers’ ability to detect potentially subtle biological factors that may contribute to prostate CHD. PCa patient-derived xenografts (PDXs) offer substantially greater fidelity to original patient tumors but are non-adherent and ultimately non-viable in extended in vitro 2D culture. Therefore, a population-based PCa platform which accurately mimics the three-dimensional (3D) tumor microenvironment (TME) is urgently needed. We have employed MIMETAS’ OrganoPlate®, a high throughput microfluidic culture platform containing 40-96 individual tissue chips, for ex vivo 3D culture of multiple racially/ethnically diverse PCa PDXs (African American, Caucasian, Hispanic) developed at MD Anderson Cancer Center (the MDA PCa PDXs series). MDA PCa PDX tumors were reconstituted from single-cell digestates into multicellular clusters, suspended within HyStem® hyaluronic acid hydrogel precursor solutions, and loaded into the OrganoPlate®. PDXs were maintained in 3D either as monocultures, as cocultures with bone marrow-derived stromal fibroblasts, or as tricultures with endothelial cell blood vessel mimics under continuous perfusion. High-content fluorescence imaging identified retention of stable, viable cultures for at least 7 days. Positive immunofluorescent staining for human nuclear antigen (HNA) confirmed that nearly 100% of encapsulated PCa cells were of human origin. For each PCa model developed, appropriate expression of phenotypic prostate-specific antigen (PSA) and androgen receptor (AR) was maintained over the life of the culture. PCa cultures were treated with various chemotherapeutic drugs and viability was monitored to generate dose response curves for comparison to clinical data. This engineered “tumor-on-a-chip” will better predict patient responses and, by incorporating PCa cells from patients with diverse ancestries, support CHD research. Citation Format: Lindsey K. Sablatura, Kristin M. Bircsak, Peter Shepherd, Rick Kittles, Pamela E. Constantinou, Anthony D. Saleh, Nora M. Navone, Daniel A. Harrington. A racially/ethnically diverse 3D PDX model of prostate cancer [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 3337.

Quantitative analysis of the ThrbCRM1-centered gene regulatory network.

ABSTRACTEnhancer activity is determined by both the activity and occupancy of transcription factors as well as the specific sequences they bind. Experimental investigation of this dynamic requires the ability to manipulate components of the system, ideally in as close to an in vivo context as possible. Here we use electroporation of plasmid reporters to define critical parameters of a specific cis-regulatory element, ThrbCRM1, during retinal development. ThrbCRM1 is associated with cone photoreceptor genesis and activated in a subset of developing retinal cells that co-express the Otx2 and Onecut1 (OC1) transcription factors. Variation of reporter plasmid concentration was used to generate dose response curves and revealed an effect of binding site availability on the number and strength of cells with reporter activity. Critical sequence elements of the ThrbCRM1 element were defined using both mutagenesis and misexpression of the Otx2 and OC1 transcription factors in the developing retina. Additionally, these experiments suggest that the ThrbCRM1 element is co-regulated by Otx2 and OC1 even under conditions of sub-optimal binding of OC1.

PO-421 A novel high-throughput drug screening platform using pancreatic ductal adenocarcinoma derived organoids in the organoplate®

Introduction Pancreatic cancer is one of the deadliest tumours due to the limited treatment options and late diagnosis. Here, we describe a novel high throughput drug screening platform combining the OrganoPlate, a microfluidic based 3D-culture plate, and the recently described Pancreatic Ductal AdenoCarcinoma (PDAC) derived organoids. Material and methods The OrganoPlate is a high throughput microfluidic 3D cell culture platform, supporting physiologically relevant models with a minimal requirement of cell material and enabling a wide range of flow and co-culture options (e.g. with blood vessels). Organoids were derived from human PDAC xenografts and seeded in the OrganoPlate. The low amount of tissue material required (4000 cells per chip) and the high number of replicates on one plate (n=96 on a standard microtiter format plate) renders the OrganoPlate an efficient and cost-effective platform for drug screening and toxicity assays on complex, 3D models. Results and discussions Organoids were exposed to various chemotherapeutic drugs for 72 hours. The viability of the organoids before and after drug treatment is monitored with standard viability assays and subsequently used to generate dose response curves. Conclusion In conclusion, we showed that the OrganoPlate can be used for high throughput drug screening assays and toxicity screening, and demonstrated its compatibility with human pancreatic PDAC derived organoids.

Stem cell derived phenotypic human neuromuscular junction model for dose response evaluation of therapeutics

There are currently no functional neuromuscular junction (hNMJ) systems composed of human cells that could be used for drug evaluations or toxicity testing in vitro. These systems are needed to evaluate NMJs for diseases such as amyotrophic lateral sclerosis, spinal muscular atrophy or other neurodegenerative diseases or injury states. There are certainly no model systems, animal or human, that allows for isolated treatment of motoneurons or muscle capable of generating dose response curves to evaluate pharmacological activity of these highly specialized functional units. A system was developed in which human myotubes and motoneurons derived from stem cells were cultured in a serum-free medium in a BioMEMS construct. The system is composed of two chambers linked by microtunnels to enable axonal outgrowth to the muscle chamber that allows separate stimulation of each component and physiological NMJ function and MN stimulated tetanus. The muscle's contractions, induced by motoneuron activation or direct electrical stimulation, were monitored by image subtraction video recording for both frequency and amplitude. Bungarotoxin, BOTOX® and curare dose response curves were generated to demonstrate pharmacological relevance of the phenotypic screening device. This quantifiable functional hNMJ system establishes a platform for generating patient-specific NMJ models by including patient-derived iPSCs.

Antibody Fragments for On-Site Testing of Cannabinoids Generated &lt;i&gt;via in Vitro&lt;/i&gt; Affinity Maturation

Law enforcement against illicit use of cannabis and related substances requires rapid, feasible, and reliable tools for on-site testing of cannabinoids. Notably, methods based on cannabinoid-specific antibodies enable efficient screening of multiple specimens. Antibody engineering may accelerate development of modern and robust testing systems. Here, we used in vitro affinity maturation to generate a single-chain Fv fragment (scFv) that recognizes with high affinity the psychoactive cannabinoid, Δ9-tetrahydrocannabinol (THC). A mouse monoclonal antibody against THC, Ab-THC#33, with Ka 6.2×107 M-1 (as Fab fragment) was established by the hybridoma technique. Then, a "wild-type" scFv (wt-scFv) with Ka, 1.1×107 M-1 was prepared by bacterial expression of a fusion gene combining the VH and VL genes for Ab-THC#33. Subsequently, random point mutations in VH and VL were generated separately, and the resulting products were assembled into mutant scFv genes, which were then phage-displayed. Repeated panning identified a mutant scFv (scFv#m1-36) with 10-fold enhanced affinity (Ka 1.1×108 M-1) for THC, in which only a single conservative substitution (Ser50Thr) was present at the N-terminus of the VH-complementarity-determining region 2 (CDR2) sequence. In competitive enzyme-linked immunosorbent assay (ELISA), the mutant scFv generated dose-response curves with midpoint 0.27 ng/assay THC, which was 3-fold lower than that of wt-scFv. Even higher reactivity with a major THC metabolite, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol, indicated that the mutant scFv will be useful for testing not only THC in confiscated materials, but also the metabolite in urine. Indeed, the antibody fragment is potentially suitable for use in advanced on-site testing platforms for cannabinoids.

Internal and external generalizability of temporal dose–response relationships for xerostomia following IMRT for head and neck cancer

Background and purposeTo study internal and external generalizability of temporal dose–response relationships for xerostomia after intensity-modulated radiotherapy (IMRT) for head and neck cancer, and to investigate potential amendments of the QUANTEC guidelines. Material and methodsObjective xerostomia was assessed in 121 patients (nCohort1=55; nCohort2=66) treated to 70Gy@2Gy in 2006–2015. Univariate and multivariate analyses (UVA, MVA with 1000 bootstrap populations) were conducted in Cohort1, and generalizability of the best-performing MVA model was investigated in Cohort2 (performance: AUC, p-values, and Hosmer–Lemeshow p-values (pHL)). Ultimately and for clinical guidance, minimum mean dose thresholds to the contralateral and the ipsilateral parotid glands (Dmeancontra, Dmeanipsi) were estimated from the generated dose–response curves. ResultsThe observed xerostomia rate was 38%/47% (3months) and 19%/23% (11–12months) in Cohort1/Cohort2. Risk of xerostomia at 3months increased for higher Dmeancontra and Dmeanipsi (Cohort1: 0.17·Dmeancontra+0.11·Dmeanipsi-8.13; AUC=0.90±0.05; p=0.0002±0.002; pHL=0.22±0.23; Cohort2: AUC=0.81; p<0.0001; pHL=0.27). The identified minimum Dmeancontra thresholds were lower than in the QUANTEC guidelines (Cohort1/Cohort2: Dmeancontra=12/19Gy; Dmeancontra, Dmeanipsi=16, 25/20, 26Gy). ConclusionsIncreased Dmeancontra and Dmeanipsi explain short-term xerostomia following IMRT. Our results also suggest decreasing Dmeancontra to below 20Gy, while keeping Dmeanipsi to around 25Gy. Long-term xerostomia was less frequent, and no dose–response relationship was established for this follow-up time.

When a discriminating dose assay is not enough: measuring the intensity of insecticide resistance in malaria vectors.

BackgroundGuidelines from the World Health Organization for monitoring insecticide resistance in disease vectors recommend exposing insects to a predetermined discriminating dose of insecticide and recording the percentage mortality in the population. This standardized methodology has been widely adopted for malaria vectors and has provided valuable data on the spread and prevalence of resistance. However, understanding the potential impact of this resistance on malaria control requires a more quantitative measure of the strength or intensity of this resistance.MethodsBioassays were adapted to quantify the level of resistance to permethrin in laboratory colonies and field populations of Anopheles gambiae sensu lato. WHO susceptibility tube assays were used to produce data on mortality versus exposure time and CDC bottle bioassays were used to generate dose response data sets. A modified version of the CDC bottle bioassay, known as the Resistance Intensity Rapid Diagnostic Test (I-RDT), was also used to measure the knockdown and mortality after exposure to different multipliers of the diagnostic dose. Finally cone bioassays were used to assess mortality after exposure to insecticide treated nets.ResultsThe time response assays were simple to perform but not suitable for highly resistant populations. After initial problems with stability of insecticide and bottle washing were resolved, the CDC bottle bioassay provided a reproducible, quantitative measure of resistance but there were challenges performing this under field conditions. The I-RDT was simple to perform and interpret although the end point selected (immediate knockdown versus 24 h mortality) could dramatically affect the interpretation of the data. The utility of the cone bioassays was dependent on net type and thus appropriate controls are needed to interpret the operational significance of these data sets.ConclusionsIncorporating quantitative measures of resistance strength, and utilizing bioassays with field doses of insecticides, will help interpret the possible impact of resistance on vector control activities. Each method tested had different benefits and challenges and agreement on a common methodology would be beneficial so that data are generated in a standardized format. This type of quantitative data are an important prerequisite to linking resistance strength to epidemiological outcomes.

Abstract A17: Cellular genomics approaches to defining toxicity pathways of chemotherapeutic agents in immune cells

Abstract Background: While the role of the immune system in cancer development is known, its role in response to chemotherapeutic agents remains elusive. Interpatient variability in immune and chemotherapeutic cytotoxic responses is likely due to complex genetic differences. Through the use of a panel of genetically diverse mouse inbred strains, we developed a drug screening platform aimed at examining novel mechanisms underlying these chemotherapeutic cytotoxic responses on immune cells. Drug effects were investigated by comparing more selective chemotherapeutic agents such as BEZ235 and selumetinib against conventional cytotoxic agents, including doxorubicin and idarubicin. Our ultimate goal is to identify genetic biomarkers to determine which patients are most likely to have an advantageous risk-benefit ratio for a particular therapy. Methods: Splenocytes were isolated from 35 isogenic strains of mice using standard procedures. Of note, the splenocytes were not stimulated to avoid attributing genes to cellular stimulation rather than toxicity. Cells at a density of 100,000 cells per well with 100 μl media were incubated with compounds on a 10-point logarithmic dosing scale ranging from 0 to 100 μM (37°C, 5% CO2). At 4 hours post-treatment, cells were labeled with antibodies and physiological indicator dyes and fixed with 4% paraformaldehyde. Cellular phenotypes (e.g., viability, mitochondrial membrane potential, and caspase activity) were collected with the BD Biosciences FACSCanto II flow cytometer and analyzed with Flow Jo version X. Dose response curves with response normalized to the zero dose as a function of log concentration were subsequently generated using GraphPad Prism 5. SNPster and EMMA algorithms were used to perform genome-wide association mapping, providing precision (1 to 2 Mb) in localizing quantitative trait loci. Potential candidate genes for validation studies were prioritized using genome-wide significance, spleen expression data, haplotype structure, biological relevance, etc. Validation of the candidate gene App consisted of isolating splenocytes from App knockout mice with a C57BL/6J background and comparing their response to idarubicin with control C57BL/6J mice. Results: Phenotypes were quantified using flow cytometry, yielding interstrain variation for measured endpoints in different immune cells. Our flow cytometry assay produced nearly 16,000 data points that were used to generate dose response curves. The more targeted agents, BEZ-235 and selumetinib, were less toxic to immune cells than the anthracycline agents. Also, heritability for the viability of immune cells was higher (approximately 70 to 90%) for anthracyclines than the novel agents (approximately 35 to 60%), making them ideal for genetic analysis. Using genome-wide association studies, we identified loci that contributed to the sensitivity of doxorubicin and idarubicin in immune cells. We identified multiple QTL containing 35 promising candidate genes. Of particular interest, App encoding for amyloid beta precursor protein was identified under a peak on chromosome 16 (p = 5.01x10-8) in T-cells exposed to idarubicin. Dose response curves verified that T-cells in App knockout mice were more sensitive to idarubicin than those in C57BL/6J control mice (p = 0.01). Conclusion: Using a cellular screening approach, we identified and subsequently validated a gene candidate encoding for amyloid beta precursor protein in T-cells exposed to idarubicin. The literature has suggested a role for App in in vitro and in vivo cytotoxicity to anticancer agents; the overexpression of App enhances resistance, while the knockdown of this gene is deleterious to cell viability. In the future, we aim to perform mechanistic studies in primary and immortalized immune cells and, ultimately, to translate our findings to in vivo and human studies. Citation Format: Amber D. Frick, Kristy Richards, Yuri Fedoriw, Russell Thomas, Timothy Wiltshire. Cellular genomics approaches to defining toxicity pathways of chemotherapeutic agents in immune cells. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr A17.