Resistant Models Research Articles

Preclinical Characterization of ARX517, a Site-specific Stable PSMA-Targeted Antibody Drug Conjugate for Treatment of Metastatic Castration-Resistant Prostate Cancer.

Metastatic castration-resistant prostate cancer (mCRPC) is an advanced disease in which patients ultimately fail standard of care androgen-deprivation therapies and exhibit poor survival rates. The prostate-specific membrane antigen (PSMA) has been validated as a mCRPC tumor antigen with over-expression in tumors and low expression in healthy tissues. Using our proprietary technology for incorporating synthetic amino acids (SAAs) into proteins at selected sites, we have developed ARX517, an antibody drug conjugate (ADC) which is composed of a humanized anti-PSMA antibody site-specifically conjugated to a tubulin inhibitor at a drug-to-antibody ratio of 2. After binding PSMA, ARX517 is internalized and catabolized, leading to cytotoxic payload delivery and apoptosis. To minimize premature payload release and maximize delivery to tumor cells, ARX517 employs a non-cleavable PEG linker and stable oxime conjugation enabled via SAA protein incorporation to ensure its overall stability. In vitro studies demonstrate that ARX517 selectively induces cytotoxicity of PSMA-expressing tumor cell lines. ARX517 exhibited a long terminal half-life and high serum exposure in mice, and dose-dependent anti-tumor activity in both enzalutamide-sensitive and -resistant CDX and PDX prostate cancer models. Repeat dose toxicokinetic studies in non-human primates demonstrated ARX517 was tolerated at exposures well above therapeutic exposures in mouse pharmacology studies, indicating a wide therapeutic index. In summary, ARX517 inhibited tumor growth in diverse mCRPC models, demonstrated a tolerable safety profile in monkeys, and had a wide therapeutic index based on preclinical exposure data. Based on the encouraging preclinical data, ARX517 is currently being evaluated in a Phase 1 clinical trial ([NCT04662580]).

ORIC-101, a Glucocorticoid Receptor Antagonist, in Combination with Nab-Paclitaxel in Patients with Advanced Solid Tumors.

In preclinical models, glucocorticoid receptor (GR) signaling drives resistance to taxane chemotherapy in multiple solid tumors via upregulation of antiapoptotic pathways. ORIC-101 is a potent and selective GR antagonist that was investigated in combination with taxane chemotherapy as an anticancer regimen preclinically and in a phase 1 clinical trial. The ability of ORIC-101 to reverse taxane resistance was assessed in cell lines and xenograft models, and a phase 1 study (NCT03928314) was conducted in patients with advanced solid tumors to determine the dose, safety, and antitumor activity of ORIC-101 with nab-paclitaxel. ORIC-101 reversed chemoprotection induced by glucocorticoids in vitro and achieved tumor regressions when combined with paclitaxel in both taxane-naïve and -resistant xenograft models. In the phase 1 study, 21 patients were treated in dose escalation and 62 patients were treated in dose expansion. All patients in dose expansion had previously progressed on a taxane-based regimen. In dose escalation, five objective responses were observed. A preplanned futility analysis in dose expansion showed a 3.2% (95% confidence interval, 0.4-11.2) objective response rate with a median progression-free survival of 2 months (95% confidence interval, 1.8-2.8) across all four cohorts, leading to study termination. Pharmacodynamic analysis of tissue and plasma showed GR pathway downregulation in most patients in cycle 1. ORIC-101 with nab-paclitaxel showed limited clinical activity in taxane-resistant solid tumors. Despite clear inhibition of GR pathway signaling, the insufficient clinical signal underscores the challenges of targeting a single resistance pathway when multiple mechanisms of resistance may be in play. Glucocorticoid receptor (GR) upregulation is a mechanism of resistance to taxane chemotherapy in preclinical cancer models. ORIC-101 is a small molecule GR inhibitor. In this phase 1 study, ORIC-101 plus nab-paclitaxel did not show meaningful clinical benefit in patients who previously progressed on taxanes despite successful GR pathway downregulation.

The efficacy of gemcitabine and docetaxel chemotherapy for the treatment of relapsed and refractory osteosarcoma: A systematic review and pre-clinical study.

Osteosarcoma is the most common primary malignancy of the bone. There is a lack of effective treatments for patients who experience relapsed osteosarcoma. One treatment for relapsed patients is gemcitabine and docetaxel combination chemotherapy (GEMDOX). This systematic review aimed to establish the efficacy of this chemotherapy regimen, as well as identify the common severe toxicities that are associated with it. Resistant osteosarcoma cell lines developed from MG-63 and HOS-143B were used to represent relapsed osteosarcoma patients in a pre-clinical study. We identified 11 retrospective and Phase II studies that were suitable for inclusion in our review. 10.65% of patients had a response to gemcitabine and docetaxel combination therapy and the disease control rate was 35% (n = 197). 36%, 35.3% and 18.04% of patients experienced grade 3 or 4 neutropenia, thrombocytopenia and anaemia respectively (n = 133). Male patients (X2 = 9.14, p < 0.05) and those below the age of 18 (X 2 = 10.94, p < 0.05) responded better to GEMDOX treatment than females and patients older than 18 years. The resistant osteosarcoma cell lines remained sensitive to either single-agent gemcitabine, docetaxel, and the combination of both. Cisplatin-resistant models (MG-63/CISR8 & HOS-143B/CISR8) were the most responsive to GEMDOX treatment compared to doxorubicin, methotrexate, and triple-combination resistant models. GEMDOX treatment has potential efficacy in relapsed osteosarcoma patients especially those with cisplatin resistance. To directly compare the efficacy of GEMDOX therapy against other therapies randomised phase III clinical trials with adequate patient follow up must be performed to improve treatment options for osteosarcoma.

Neratinib plus dasatinib is highly synergistic in HER2-positive breast cancer in vitro and in vivo

BackgroundHER2-targeted therapies have revolutionised the treatment of HER2-positive breast cancer. However, de novo resistance or the emergence of acquired resistance is a persistent clinical problem. Here we report that neratinib, an irreversible pan-HER inhibitor, in combination with the multi-kinase inhibitor dasatinib, currently used to treat certain leukemias, has strong anti-proliferative effects against models of HER2-positive breast cancer that are innately resistant to trastuzumab or have acquired resistance to neratinib. MethodsNeratinib plus dasatinib was examined in a panel of 20 breast cancer cell lines, including HER2-positive, estrogen-receptor-positive, triple negative, and acquired HER2-targeted therapy resistant models. Drug effects on migration and apoptosis induction was evaluated and signaling alterations were determined by reverse phase protein array (RPPA). In vivo efficacy was examined using orthotopically-implanted HCC1954 cells. ResultsSynergy was observed in cell lines innately resistant to trastuzumab, models with acquired resistance to neratinib, and in triple negative breast cancer cell lines. Further investigation showed that neratinib plus dasatinib induced apoptosis and inhibited cell migration to a greater degree than either drug alone. RPPA revealed that the combination caused suppression of key survival signaling through EGFR, Akt, and MAPK inhibition. In vivo, neratinib plus dasatinib was well tolerated and had a prolonged anti-tumor effect against HCC1954 xenografts. ConclusionsThis study provides a strong pre-clinical rationale for the clinical investigation neratinib and dasatinib in HER2+ breast cancer.

Targeting Super-Enhancer-Driven Transcriptional Dependencies Suppresses Aberrant Hedgehog Pathway Activation and Overcomes Smoothened Inhibitor Resistance.

Aberrant activation of the Hedgehog (Hh) signaling pathway plays important roles in oncogenesis and therapeutic resistance in several types of cancer. The clinical application of FDA-approved Hh-targeted smoothened inhibitors (SMOi) is hindered by the emergence of primary or acquired drug resistance. Epigenetic and transcriptional-targeted therapies represent a promising direction for developing improved anti-Hh therapies. In this study, we integrated epigenetic/transcriptional-targeted small-molecule library screening with CRISPR/Cas9 knockout library screening and identified CDK9 and CDK12, two transcription elongation regulators, as therapeutic targets for antagonizing aberrant Hh activation and overcoming SMOi resistance. Inhibition of CDK9 or CDK12 potently suppressed Hh signaling and tumor growth in various SMOi responsive or resistant Hh-driven tumor models. Systemic epigenomic profiling elucidated the Hh-driven super-enhancer (SE) landscape and identified IRS1, encoding a critical component and cytoplasmic adaptor protein of the insulin-like growth factor (IGF) pathway, as an oncogenic Hh-driven SE target gene and effective therapeutic target in Hh-driven tumor models. Collectively, this study identifies SE-driven transcriptional dependencies that represent promising therapeutic vulnerabilities for suppressing the Hh pathway and overcoming SMOi resistance. As CDK9 and IRS inhibitors have already entered human clinical trials for cancer treatment, these findings provide comprehensive preclinical support for developing trials for Hh-driven cancers. Significance: Dissecting transcriptional dependencies driven by super-enhancers uncovers therapeutic targets in Hedgehog-driven cancers and identifies strategies for overcoming resistance to smoothened inhibitors.

The first-in-class pro-apoptotic peptide PEP-010 is effective in monotherapy and in combination with paclitaxel on resistant ovarian adenocarcinoma cell models.

Ovarian adenocarcinoma is the gynecological malignancy with the worst prognosis and the highest mortality rate. In the first stages of treatment, chemotherapy results effective, but its prolonged use and high doses lead to the appearance of resistance to treatments and relapse in most patients, representing a major challenge for clinicians. We developed PEP-010, a cell penetrating proapoptotic peptide disrupting the protein-protein interaction between caspase-9 and protein phosphatase 2A, thereby leading to the recovery of their activity in the apoptotic pathway. MTT assay or Annexin-V/Propidium Iodide staining and flow cytometry analysis were used to assess sensitivity to chemotherapies and apoptosis after treatment with PEP-010 in monotherapy or in combination with paclitaxel in ovarian carcinoma cell lines. DNA damage was assessed by immunofluorescence using γH2AX marker. We show here that PEP-010 effectively induces cell death in monotherapy on in up to 55% of cells from ovarian adenocarcinoma cell models resistant to different chemotherapies. Moreover, when used in combination with paclitaxel, one of the therapeutic options for recurrent ovarian carcinoma, PEP-010 showed a beneficial effect leading to the reduction of the IC50 of paclitaxel of 2.2 times and to apoptosis in 87% of cells. The described results suggest the potential therapeutic interest for PEP-010 and lead to the choice of ovarian adenocarcinoma as one of the major indications of the ongoing clinical trial.

Sonodynamic Treatment Triggers Cancer Cell Killing by Doxorubicin in P‐Glycoprotein‐Mediated Multidrug Resistant Cancer Models

Sonodynamic Treatment Triggers Cancer Cell Killing by Doxorubicin in P‐Glycoprotein‐Mediated Multidrug Resistant Cancer Models

Effects of Resistivity on the Reconstructed Plasma Fields Revealed by a Three‐Dimensional Empirical Reconstruction Model

AbstractWe extend the previous three‐dimensional (3D) empirical reconstruction (ER) model for a set of ideal magnetohydrodynamics (MHD) constraints into a resistive MHD 3D ER model that includes additional resistive MHD constraints and additional measurements from NASA's Magnetospheric Multiscale (MMS) mission. The same form of a stochastic optimization algorithm is used as in the previous ideal MHD 3D ER model to directly minimize the loss function that includes a few more highly nonlinear terms characterizing the model‐measurement differences and the model departures from physical constraints. The resistive MHD 3D ER model is applied to three regions of MMS measurements that correspond to direct sampling of an electron diffusion region (EDR), a region adjacent to the EDR, and one far away from the EDR. The reconstructed plasma and electromagnetic fields are of high quality in all three regions as measured by model‐measurement difference indices and physics‐based quality indicators. The reconstructed fields in the EDR provide us with a good view of the spatial configuration of the reconnection site. We specifically examine the effect of resistivity on energy exchange in the vicinity of the EDR. It was discovered that in the EDR, the energy exchange shows an exclusive and systematic one‐channel process between the plasma thermal energy and electromagnetic energy with the conversion rate highly correlated with the strength of the turbulent electromagnetic fields. In the other two regions away from the EDR, the energy exchange between the electromagnetic energy and the plasma thermal and kinetic energies shows rapidly‐varying and random characteristics.

LX1 Dual Targets AR Variants and AKR1C3 in Advanced Prostate Cancer Therapy.

The development of resistance to current standard-of-care treatments, such as androgen receptor (AR) targeting therapies, remains a major challenge in the management of advanced prostate cancer. There is an urgent need for new therapeutic strategies targeting key resistant drivers, such as AR variants like AR-V7, and steroidogenic enzymes, such as aldo-keto reductase 1C3 (AKR1C3), to overcome drug resistance and improve outcomes for patients with advanced prostate cancer. Here, we have designed, synthesized, and characterized a novel class of LX compounds targeting both the AR/AR variants and AKR1C3 pathways. Molecular docking and in vitro studies demonstrated that LX compounds bind to the AKR1C3 active sites and inhibit AKR1C3 enzymatic activity. LX compounds were also shown to reduce AR/AR-V7 expression and to inhibit their target gene signaling. LX1 inhibited the conversion of androstenedione into testosterone in tumor-based ex vivo enzyme assays. In addition, LX1 inhibited the growth of cells resistant to antiandrogens including enzalutamide (Enza), abiraterone, apalutamide, and darolutamide in vitro. A synergistic effect was observed when LX1 was combined with antiandrogens and taxanes, indicating the potential for this combination in treating resistant prostate cancer. Treatment with LX1 significantly decreased tumor volume, serum PSA levels, as well as reduced intratumoral testosterone levels, without affecting mouse body weight. Furthermore, LX1 was found to overcome resistance to Enza treatment, and its combination with Enza further suppressed tumor growth in both the CWR22Rv1 xenograft and LuCaP35CR patient-derived xenograft models. Collectively, the dual effect of LX1 in reducing AR signaling and intratumoral testosterone, along with its synergy with standard therapies in resistant models, underscores its potential as a valuable treatment option for advanced prostate cancer. Significance: LX1 simultaneously targets androgen receptor variants and the steroidogenic enzyme AKR1C3, offering a promising approach to combat drug resistance and enhancing therapeutic efficacy in conjunction with standard treatments for advanced prostate cancer.

Efficacy of novel allogeneic cancer cells vaccine to treat colorectal cancer.

Colorectal cancer (CRC) remains a significant global health burden, emphasizing the need for innovative treatment strategies. 95% of the CRC population are microsatellite stable (MSS), insensitive to classical immunotherapies such as anti-PD-1; on the other hand, responders can become resistant and relapse. Recently, the use of cancer vaccines enhanced the immune response against tumor cells. In this context, we developed a therapeutic vaccine based on Stimulated Tumor Cells (STC) platform technology. This vaccine is composed of selected tumor cell lines stressed and haptenated in vitro to generate a factory of immunogenic cancer-related antigens validated by a proteomic cross analysis with patient's biopsies. This technology allows a multi-specific education of the immune system to target tumor cells harboring resistant clones. Here, we report safety and antitumor efficacy of the murine version of the STC vaccine on CT26 BALB/c CRC syngeneic murine models. We showed that one cell line (1CL)-based STC vaccine suppressed tumor growth and extended survival. In addition, three cell lines (3CL)-based STC vaccine significantly improves these parameters by presenting additional tumor-related antigens inducing a multi-specific anti-tumor immune response. Furthermore, proteomic analyses validated that the 3CL-based STC vaccine represents a wider quality range of tumor-related proteins than the 1CL-based STC vaccine covering key categories of tumor antigens related to tumor plasticity and treatment resistance. We also evaluated the efficacy of STC vaccine in an MC38 anti-PD-1 resistant syngeneic murine model. Vaccination with the 3CL-based STC vaccine significantly improved survival and showed a confirmed complete response with an antitumor activity carried by the increase of CD8+ lymphocyte T cells and M1 macrophage infiltration. These results demonstrate the potential of this technology to produce human vaccines for the treatment of patients with CRC.

PI3K/AKT confers intrinsic and acquired resistance to pirtobrutinib in chronic lymphocytic leukemia

PurposePirtobrutinib, a non-covalent Bruton’s tyrosine kinase (BTK) inhibitor, has been approved as the first agent to overcome resistance to covalent BTK inhibitors (such as ibrutinib, acalabrutinib, and zanubrutinib). However, the mechanisms of pirtobrutinib resistance in chronic lymphocytic leukemia (CLL) remain poorly understood. MethodsTo investigate pirtobrutinib resistance, we established resistant cell models using BTK knock-out via CRISPR-Cas9 or chronic exposure to pirtobrutinib in MEC-1 cells. These models mimicked intrinsic or acquired resistance, respectively. We then analyzed differential protein expression between wild-type (WT) and resistant MEC-1 cells using Revers Phase Protein microArray (RPPA) and confirmed the findings through Western Blot. Additionally, we evaluated potential drugs to overcome pirtobrutinib resistance by conducting cell proliferation assays, apoptosis studies, and animal experiments using both sensitive and resistant cells. ResultsMEC-1 cells developed resistance to pirtobrutinib either through BTK knock-out or prolonged drug exposure over three months. RPPA analysis revealed significant activation of proteins related to the PI3K/AKT pathway, including AKT and S6, in the resistant cells. Western Blot confirmed increased phosphorylation of AKT and S6 in pirtobrutinib-resistant MEC-1 cells. Notably, both the PI3K inhibitor (CAL101) and the AKT inhibitor (MK2206) effectively reduced cell proliferation and induced apoptosis in the resistant cells. The anti-tumor efficacy of these drugs was mediated by inhibiting the PI3K/AKT pathway. In vivo animal studies further supported the potential of targeting PI3K/AKT to overcome both intrinsic and acquired resistance to pirtobrutinib. ConclusionThe PI3K/AKT pathway plays a crucial role in both intrinsic and acquired resistance to pirtobrutinib in CLL. Therapeutically targeting this pathway may offer a promising strategy to overcome pirtobrutinib resistance.

EstroGene2.0: A multi-omic database of response to estrogens, ER-modulators, and resistance to endocrine therapies in breast cancer.

Endocrine therapies targeting the estrogen receptor (ER/ESR1) are the cornerstone to treat ER-positive breast cancers patients, but resistance often limits their effectiveness. Understanding the molecular mechanisms is thus key to optimize the existing drugs and to develop new ER-modulators. Notable progress has been made although the fragmented way data is reported has reduced their potential impact. Here, we introduce EstroGene2.0, an expanded database of its precursor 1.0 version. EstroGene2.0 focusses on response and resistance to endocrine therapies in breast cancer models. Incorporating multi-omic profiling of 361 experiments from 212 studies across 28 cell lines, a user-friendly browser offers comprehensive data visualization and metadata mining capabilities (https://estrogeneii.web.app/). Taking advantage of the harmonized data collection, our follow-up meta-analysis revealed substantial diversity in response to different classes of ER-modulators including SERMs, SERDs, SERCA and LDD/PROTAC. Notably, endocrine resistant models exhibit a spectrum of transcriptomic alterations including a contra-directional shift in ER and interferon signaling, which is recapitulated clinically. Furthermore, dissecting multiple ESR1-mutant cell models revealed the different clinical relevance of genome-edited versus ectopic overexpression model engineering and identified high-confidence mutant-ER targets, such as NPY1R. These examples demonstrate how EstroGene2.0 helps investigate breast cancer's response to endocrine therapies and explore resistance mechanisms.

Screening of Drought-Resistant Potato Germplasm Resources Based on Intelligent Algorithm

As a staple food resource, potato is of great significance for improving grain reserves and ensuring national food security. In order to improve potato yield and promote the process of potato becoming a staple food, a K-means algorithm optimized by particle swarm algorithm was proposed to realize the screening of dry potato germplasm resources. First, the research continues the research on particle swarm optimization, and innovatively applies K-means algorithm to optimization. The research utilizes the advantages of particle swarm optimization, such as fast convergence speed, strong search ability, and simple operation, to enable particle swarm optimization to take on the role of optimizing the initial clustering center, thereby improving the accuracy and efficiency of clustering analysis. On this basis, a PSO-K-means drought resistant potato germplasm resource screening model was constructed. This model consists of a data collection and preprocessing module, an impact indicator determination module, and a comprehensive evaluation module. Finally, the application effect of the model was verified. The results show that the AUC value of the model is up to 0.840, and the screening accuracy is as high as 94.5%, which is 13.5% higher than that of the K-means model. The research method has been validated to improve the limitations of K-means mode, such as high screening error, weak stability, and falling into local optimal solutions. It optimizes the screening effect of drought resistant potato germplasm resources, which is conducive to exploring the potential of potato resources. In addition, research has also provided broader ideas for the optimization and application of particle swarm optimization algorithms.

New hemisynthetic derivatives of sphaeropsidin phytotoxins triggering severe endoplasmic reticulum swelling in cancer cells

Sphaeropsidins are iso-pimarane diterpenes produced by phytopathogenic fungi that display promising anticancer activities. Sphaeropsidin A, in particular, has been shown to counteract regulatory volume increase, a process used by cancer cells to avoid apoptosis. This study reports the hemi-synthesis of new lipophilic derivatives obtained by modifications of the C15,C16-alkene moiety. Several of these compounds triggered severe ER swelling associated with strong proteasomal inhibition and consequently cell death, a feature that was not observed with respect to mode of action of the natural product. Significantly, an analysis from the National Cancer Institute sixty cell line testing did not reveal any correlations between the most potent derivative and any other compound in the database, except at high concentrations (LC50). This study led to the discovery of a new set of sphaeropsidin derivatives that may be exploited as potential anti-cancer agents, notably due to their maintained activity towards multidrug resistant models.

Intercellular adhesion molecule-1 suppresses TMZ chemosensitivity in acquired TMZ-resistant gliomas by increasing assembly of ABCB1 on the membrane

AimsDespite aggressive treatment, the recurrence of glioma is an inevitable occurrence, leading to unsatisfactory clinical outcomes. A plausible explanation for this phenomenon is the phenotypic alterations that glioma cells undergo aggressive therapies, such as TMZ-therapy. However, the underlying mechanisms behind these changes are not well understood. MethodsThe TMZ chemotherapy resistance model was employed to assess the expression of intercellular adhesion molecule-1 (ICAM1) in both in vitro and in vivo settings. The potential role of ICAM1 in regulating TMZ chemotherapy resistance was investigated through knockout and overexpression techniques. Furthermore, the mechanism underlying ICAM1-mediated TMZ chemotherapy resistance was examined using diverse molecular biological methods, and the lipid raft protein was subsequently isolated to investigate the cellular subcomponents where ICAM1 operates. ResultsAcquired TMZ resistant (TMZ-R) glioma models heightened production of intercellular adhesion molecule-1 (ICAM1) in TMZ-R glioma cells. Additionally, we observed a significant suppression of TMZ-R glioma proliferation upon inhibition of ICAM1, which was attributed to the enhanced intracellular accumulation of TMZ. Our findings provide evidence supporting the role of ICAM1, a proinflammatory marker, in promoting the expression of ABCB1 on the cell membrane of TMZ-resistant cells. We have elucidated the mechanistic pathway by which ICAM1 modulates phosphorylated moesin, leading to an increase in ABCB1 expression on the membrane. Furthermore, our research has revealed that the regulation of moesin by ICAM1 was instrumental in facilitating the assembly of ABCB1 exclusively on the lipid raft of the membrane. ConclusionsOur findings suggest that ICAM1 is an important mediator in TMZ-resistant gliomas and targeting ICAM1 may provide a new strategy for enhancing the efficacy of TMZ therapy against glioma.

Aurora Kinase A inhibition enhances DNA damage and tumor cell death with 131I-MIBG therapy in high-risk neuroblastoma

BackgroundNeuroblastoma is the most common extra-cranial pediatric solid tumor. 131I-metaiodobenzylguanidine (MIBG) is a targeted radiopharmaceutical highly specific for neuroblastoma tumors, providing potent radiotherapy to widely metastatic disease. Aurora kinase A (AURKA) plays a role in mitosis and stabilization of the MYCN protein in neuroblastoma. We aimed to study the impact of AURKA inhibitors on DNA damage and tumor cell death in combination with 131I-MIBG therapy in a pre-clinical model of high-risk neuroblastoma.ResultsUsing an in vivo model of high-risk neuroblastoma, we demonstrated a marked combinatorial effect of 131I-MIBG and alisertib on tumor growth. In MYCN amplified cell lines, the combination of radiation and an AURKA A inhibitor increased DNA damage and apoptosis and decreased MYCN protein levels.ConclusionThe combination of AURKA inhibition with 131I-MIBG treatment is active in resistant neuroblastoma models.

Modelling and experiment to stabilize disruptive tearing modes in the ITER baseline scenario in DIII-D

The achievement of high gain, stationary conditions in a tokamak scenario aimed at producing fusion energy in the ITER Project is crucial to the demonstration that this form of energy can be used in future reactors to provide cheap and clean energy globally. Disruptions are a challenge for the fusion energy field, in particular for the ‘ITER Baseline Scenario’ (IBS), as reproduced in the DIII-D tokamak. This work shows that a solution has been found for the m= 2/n = 1 tearing modes that have consistently caused disruptions in the IBS: stable operation down to zero input torque was achieved by modifying the current density profile at the beginning of the pressure flattop and the ELM character later in the discharges, guided by previous results showing that the most likely cause of these instabilities is the current density profile. The coupling between sawteeth, n>2 modes and the 2/1 TMs is shown to not be statistically significant, nor the leading origin for the evolution towards instability. Ideal and resistive MHD modeling provide positive verification that a steeper ‘well’ in the region of the q = 2 rational surface leads to worse ideal stability, higher tearing index Δ’ and lower threshold Δ’c for resistive instabilities, consistent with the experimental results. This provides confidence that the methods used in this work can be extrapolated to other devices and applied to avoid disruptions in ITER and pulsed fusion devices worldwide.

Abstract B026: Screening non-small cell lung cancer patient-derived organoids with epigenetic probes reveals PRMT5 as an oncogenic target

Abstract Lung cancer is the leading cause of cancer-related mortality. Detection of drug actionable genetic alterations has made the standard systemic therapy to a more personalized one including targeted therapy and immune checkpoint blockade. Despite the initial response, majority of patients develop resistance to treatment. Therefore, understanding the mechanisms of resistance as well as discovering novel cancer targets is necessary. Resistance to therapies can be associated with an existing clone of tumor cells with genetic alteration, or the emergence of cells with epigenetic changes overcoming the treatment-induced stress. Therefore, investigating the epigenetic aberrations that occur in tumor cells may reveal novel targetable markers that can be of great clinical significance. Methods: Organoid models established from non-small cell lung cancer (NSCLC) patient surgical resections and pleural effusion were dissociated into single cells and plated in matrigel-coated 384-well plate. A panel of 32 NSCLC organoid models were treated with a library of 41 epigenetic probes (1uM) and a DMSO control over a period of 8 days. Cell titre glo assay was performed to measure cell survival. Results: Arginine methyl transferase protein 5 (PRMT5) inhibited the cell growth of large proportion of the NSCLC organoid models. LLY-283 showed the most significant effect, with 50% of all organoid models (16/32) treated with LLY283 showing ≥50% reduction in cell viability. Further testing with multiple concentrations of several PRMT5 inhibitors revealed models with differential responses to PRMT5 inhibition. To investigate the differential gene expression changes induced by PRMT5 inhibition, we performed RNA-sequencing on three PRMT5 inhibitor sensitive and three resistant organoid models. Ongoing analyses aim at identifying differentially expressed genes in sensitive and resistant models in response to PRMT5 inhibition, and pathway enrichment analysis to determine the differential mechanisms of response to PRMT5 inhibition. Conclusion: Epigenetic drug screening on a large cohort of NSCLC organoid models reveals PRMT5 as potential novel therapeutic target in NSCLC. Further correlative analysis with transcriptomic changes induced by the PRMT5 inhibitors may reveal biomarkers of response. Citation Format: Khadija Jafarova, Quan Li, Nikolina Radulovich, Geoffrey Liu, Ming S Tsao. Screening non-small cell lung cancer patient-derived organoids with epigenetic probes reveals PRMT5 as an oncogenic target [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Expanding and Translating Cancer Synthetic Vulnerabilities; 2024 Jun 10-13; Montreal, Quebec, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(6 Suppl):Abstract nr B026.

Unraveling radiation resistance strategies in two bacterial strains from the high background radiation area of Chavara-Neendakara: A comprehensive whole genome analysis.

This paper reports the results of gamma irradiation experiments and whole genome sequencing (WGS) performed on vegetative cells of two radiation resistant bacterial strains, Metabacillus halosaccharovorans (VITHBRA001) and Bacillus paralicheniformis (VITHBRA024) (D10 values 2.32 kGy and 1.42 kGy, respectively), inhabiting the top-ranking high background radiation area (HBRA) of Chavara-Neendakara placer deposit (Kerala, India). The present investigation has been carried out in the context that information on strategies of bacteria having mid-range resistance for gamma radiation is inadequate. WGS, annotation, COG and KEGG analyses and manual curation of genes helped us address the possible pathways involved in the major domains of radiation resistance, involving recombination repair, base excision repair, nucleotide excision repair and mismatch repair, and the antioxidant genes, which the candidate could activate to survive under ionizing radiation. Additionally, with the help of these data, we could compare the candidate strains with that of the extremely radiation resistant model bacterium Deinococccus radiodurans, so as to find the commonalities existing in their strategies of resistance on the one hand, and also the rationale behind the difference in D10, on the other. Genomic analysis of VITHBRA001 and VITHBRA024 has further helped us ascertain the difference in capability of radiation resistance between the two strains. Significantly, the genes such as uvsE (NER), frnE (protein protection), ppk1 and ppx (non-enzymatic metabolite production) and those for carotenoid biosynthesis, are endogenous to VITHBRA001, but absent in VITHBRA024, which could explain the former's better radiation resistance. Further, this is the first-time study performed on any bacterial population inhabiting an HBRA. This study also brings forward the two species whose radiation resistance has not been reported thus far, and add to the knowledge on radiation resistant capabilities of the phylum Firmicutes which are abundantly observed in extreme environment.

Nucleotide metabolism in cancer cells fuels a UDP-driven macrophage cross-talk, promoting immunosuppression and immunotherapy resistance

Many individuals with cancer are resistant to immunotherapies. Here, we identify the gene encoding the pyrimidine salvage pathway enzyme cytidine deaminase (CDA) among the top upregulated metabolic genes in several immunotherapy-resistant tumors. We show that CDA in cancer cells contributes to the uridine diphosphate (UDP) pool. Extracellular UDP hijacks immunosuppressive tumor-associated macrophages (TAMs) through its receptor P2Y6. Pharmacologic or genetic inhibition of CDA in cancer cells (or P2Y6 in TAMs) disrupts TAM-mediated immunosuppression, promoting cytotoxic T cell entry and susceptibility to anti-programmed cell death protein 1 (anti-PD-1) treatment in resistant pancreatic ductal adenocarcinoma (PDAC) and melanoma models. Conversely, CDA overexpression in CDA-depleted PDACs or anti-PD-1-responsive colorectal tumors or systemic UDP administration (re)establishes resistance. In individuals with PDAC, high CDA levels in cancer cells correlate with increased TAMs, lower cytotoxic T cells and possibly anti-PD-1 resistance. In a pan-cancer single-cell atlas, CDAhigh cancer cells match with T cell cytotoxicity dysfunction and P2RY6high TAMs. Overall, we suggest CDA and P2Y6 as potential targets for cancer immunotherapy.