Cell Patient-derived Xenograft Research Articles

Synergistic effects of the combination of trametinib and alpelisib in anaplastic thyroid cancer with BRAF and PI3KCA co-mutations

BackgroundAnaplastic thyroid cancer (ATC), a rare and aggressive malignancy with a poor prognosis, has shown promise with the approved dabrafenib/trametinib combination for BRAFV600E mutation. Co-occurring PI3KCA mutations, identified as negative prognostic factors in lung cancer with BRAFV600E mutation, emphasize the need to target both pathways. Exploring trametinib and alpelisib combination becomes crucial for ATC. MethodsA patient-derived xenograft (PDX) and primary cell line were obtained from an ATC patient with BRAF and PI3KCA co-mutation. Individual testing of targeted therapies against BRAF, MEK, and PI3KCA was followed by a combination treatment. Synergistic effects were evaluated using the combination index. Immunoblotting assessed the efficacy, with validation performed using a PDX model. ResultsIn this study, the ATC0802 cell line and PDX were established from a refractory ATC patient. NGS revealed BRAF and PI3KCA co-mutations pre- and post-dabrafenib/trametinib treatment. Trametinib/alpelisib combination showed synergy, suppressing both pERK and pAKT levels, unlike monotherapies or BRAF knockdown. The combination induced apoptosis and, in the PDX model, demonstrated superior tumor growth inhibition compared to monotherapies. ConclusionsThe combination of trametinib and alpelisib showed promise as a strategy for treating ATC with co-mutations in BRAF and PI3KCA, both in vitro and in vivo. This combination offers insights into overcoming resistance to BRAF-targeted treatments in ATC with mutations in BRAF and PI3KCA.

Abstract 937: Prioritizing treatment targets for an adolescent with metastatic processive malignancy using proteomics and personalized xenograft models within an actionable timeframe

Abstract Translation of precision oncology data into feasible precision therapies for hard-to-cure childhood, adolescent and young adult malignancies remains a significant challenge. Identifying therapeutic targets at the protein and pathway level and demonstrating treatment response in personalized models hold great promise, particularly for combination therapies, but may be considered complex and time consuming. Here, we present the case of an adolescent with metastatic, progressive spindle epithelial tumor with thymus-like differentiation (SETTLE) and evaluate how proteomics combined with rapid patient-derived models can identify treatment options not apparent at the genome or transcript level. Mass spectrometric proteome analysis of macro-dissected tumor and adjacent normal from formalin fixed paraffin embedded sections was completed within two weeks of biopsy and identified key proteins involved in one-carbon metabolism, including SHMT2 and DHFR as possible targets for single or combination therapy. Elevated SHMT2 levels were validated by immunohistochemistry and compared to levels across AYA tumors. Based on the suitability for an innovative therapy trial, we prioritized single-agent sertraline, a commercially available anti-depressant medication that inhibits SHMT2, and confirmed a positive drug response in both chicken chorioallantoic membrane (CAM) and larval zebrafish xenografts generated from the patient. Retrospective expansion in a murine xenograft enabled metabolic tracing on isolated SETTLE- patient-derived xenograft cells using 13C6-glucose confirming SHMT2 activity and response to in vitro treatment. Following failure of cytotoxic chemotherapy and second-line sorafenib treatment, a monotherapy trial of sertraline was initiated by the patient but stopped after 8 weeks after evidence of progressive disease. Possible combination therapies were evaluated further in the patient-derived models. Combining sertraline with the common antibiotic trimethoprim, resulted in enhanced growth inhibition of SETTLE cells in the larval zebrafish xenografts. Significance: Overall, we demonstrate that proteomics and personalized xenograft models may provide supportive pre-clinical data in a clinically meaningful timeframe to support medical decision-making and impact clinical practice. Citation Format: Georgina D. Barnabas, Tariq A. Bhat, Verena Goebeler, Pascal Leclair, Nadine Azzam, Nicole Melong, Jason N. Berman, Jennifer A. Chan, Donna L. Senger, Seth Parker, Christopher A. Maxwell, Gregor S. Reid, Jonathan Bush, Caron Strahlendorf, Rebecca Deyell, C James Lim, Philipp F. Lange. Prioritizing treatment targets for an adolescent with metastatic processive malignancy using proteomics and personalized xenograft models within an actionable timeframe [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 937.

Abstract 5905: Propentofylline enhances GBM sensitivity to temozolomide via targeting TROY signaling

Abstract Glioblastoma (GBM) is a high grade glioma that accounts for the majority of primary malignant brain tumors. The standard of care for GBM consists of maximal surgical resection, concurrent radiation and temozolomide (TMZ), and adjuvant TMZ. However, this has only led to a modest increase in median patient survival. TROY (TNFRSF19) is an orphan member of the TNF receptor superfamily that is differentially upregulated in GBM with low expression in normal brain tissue. Previously, we have reported that TROY is overexpressed in GBM and signals to mediate cell invasion and therapeutic resistance. Propentofylline (PPF) is a well-studied synthetic methylxanthine derivative that has strong BBB penetrance. We have shown that PPF decreases TROY expression in gliomas, inhibits invasion, and sensitizes GBM to TMZ in vitro. Here we examined the efficacy of PPF in combination with TMZ using in vivo studies of intracranial models of GBM patient-derived xenograft (PDX) models in murine. We tested 3 models of GBM PDX cells with various TROY expression levels (GBM8-high TROY; GBM43-moderate TROY; GBM22-low/no TROY). Our intracranial PDX experiments showed that PPF treatment alone did not increase survival in all PDX cells. The combination of PPF and TMZ treatment did provide a survival benefit (p < 0.039) relative to TMZ alone (only in GBM8-high TROY and GBM43-moderate TROY) that was partially lost when treatment was discontinued. However, continuous PPF administration following a concomitant PPF and TMZ treatment course led to extended survival (p < 0.0015) compared to TMZ alone resulting in increased DNA damage (γH2AX) and apoptotic markers (Cleaved Caspase-3). Immunohistochemical analyses showed that TROY expression was decreased in tumors treated with PPF. In addition, PPF-treated tumors showed a differential myeloid population with well circumscribed tumors as compared to control-treated or TMZ-treated tumors. Thus, our data demonstrates that PPF may provide a pharmacological approach to targeting TROY concomitant with standard-of-care to increase patient survival. Citation Format: Ryan Eghlimi, David Nascari, Angad Beniwal, Drake Alton, Dustin Grief, Joseph Loftus, Melanie Haluska, David Coleman, Nhan Tran. Propentofylline enhances GBM sensitivity to temozolomide via targeting TROY signaling [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 5905.

Abstract 1392: Neutrophil extracellular trap (NET)-induced pancreatic tumor metastasis requires integrin-linked kinase (ILK) signaling

Abstract Neutrophil extracellular traps (NETs) are an important contributor to the immunosuppressive tumor microenvironment and facilitate metastasis of solid cancers. NETs have been shown to stimulate breast and colon cancer cell metastasis through a mechanism potentially involving an interaction between integrin-linked kinase (ILK) and the cell surface receptor coiled-coil domain containing protein 25 (CCDC25). Here, we have interrogated whether ILK is required for NET-induced metastasis in pancreatic ductal adenocarcinoma (PDAC), an inflammation-driven tumor that is difficult to treat. Evaluation of the circulating neutrophil to lymphocyte ratio (NLR) in the blood samples of patients presenting with metastatic PDAC showed that a higher baseline NLR is associated with significantly shorter overall patient survival. Western blot and immunofluorescence analyses demonstrated that human PDAC cell lines, patient-derived xenograft cells, cells derived from the KPCY genetic model of PDAC and patient-derived organoids co-express CCDC25 and ILK. Co-immunoprecipitation analyses showed that CCDC25 and ILK associate in both mouse and human PDAC cells, and that exposure of the cells to NETs results in an increased amount of ILK associated with CCDC25. Exposure of human and KPCY mouse PDAC cells to NETs increases phosphorylation of GSK3-β and ERK, increases activation of Rac1 and Cdc42 and upregulates markers of epithelial-to-mesenchymal transition (EMT), including ZEB1 and Snail, in a time and concentration-dependent manner. Furthermore, time-lapse imaging using Incucyte-based wounding assays showed that exposure to NETs induces pseudopodia-like protrusions, migration and invasion by these cells. RNAi-mediated suppression of ILK expression or inhibition of ILK activity using a highly selective inhibitor of ILK, QLT-0267, significantly inhibits the NET-induced increase in GSK3-β phosphorylation, Rac1/Cdc42 activation, migration and invasion of PDAC cells. In vivo, co-localization of CCDC25 and ILK is observed in tumors and metastases from KPCY mouse and MIA PaCa-2 human PDAC xenograft models stained by multispectral immunofluorescence and analyzed by confocal microscopy. Tumors and metastases show the presence of infiltrating neutrophils and NETs as indicated by staining for myeloperoxidase and citrullinated histone H3. Importantly, doxycycline-inducible shRNA-mediated suppression of ILK expression by luciferase-positive PDAC cells following injection of these cells through the tail vein of mice administered LPS intranasally results in a significant reduction in metastasis as measured by bioluminescence-based imaging, compared to control animals. Collectively, these data identify NET-induced ILK signaling as an important contributor to PDAC progression and suggest the potential for targeting this axis to prevent PDAC progression and metastasis. Citation Format: Paul C. McDonald, Shannon J. Awrey, Hossein Tavakoli, Rebekah Carroll, Zachary J. Gerbec, Joanna M. Karasinska, David F. Schaeffer, Daniel J. Renouf, Shoukat Dedhar. Neutrophil extracellular trap (NET)-induced pancreatic tumor metastasis requires integrin-linked kinase (ILK) signaling [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 1392.

Abstract 6914: Genomic landscape and stability of preclinical models in NCI's patient-derived models repository

Abstract Background: Patient-derived xenograft (PDX) models serve as a powerful tool for cancer translational research. However, it is unclear to what extent PDX models reflect the genomic intratumoral heterogeneity and genomic aberrations present within the original tumor sample. The National Cancer Institute (NCI) has developed a Patient-Derived Models Repository (PDMR; https://pdmr.cancer.gov/) consisting of PDX, organoids (PDOrg), and tumor cell cultures (PDC) from patients with diverse cancer histologies. We have conducted an in-depth investigation into the genomic stability of PDXs at early passaging and tumor heterogeneity in a large set of preclinical models including rare cancers. Methods: Tumor specimens were used to establish 1114 models from 1034 patients. For whole exome sequencing (WES) and RNASeq analysis, 1059 models with at least 1 PDX sample and 55 models with only a PDC or PDOrg were used. Analyzed specimens represent the original patient specimens, PDX passages P0, P1, P2, and P3+ and in vitro models. 80% of the PDX specimens were within passages P0 to P2. Results: Genomic stability in PDMR models was maintained through early passages (P0 - P2) and across independent lineages in PDMR models based on the following observations: 1) variant allele frequencies (VAF) of somatic driver mutations showed no major deviations (exceeding ±10%) when using the stromal fraction corrected VAF from originator data over PDX passages; 2) the median change in the fraction of genome impacted by copy number alterations (CNA) from the originator specimens through passages P0 - P2 was statistically inconsequential, although there was a significant increase in CNA fraction, from 5.3% at P0 initially to 18% by P3; 3) gene expression profiles of specimens within a given PDX model formed clusters in principal component analysis (PCA) plots and showed high correlation (>99.5% models with a Spearman coefficient of >= 0.8). The majority of the PDC and PDOrg specimens exhibited similar findings when compared to the original tumor samples. Furthermore, the positive percent agreement (PPA) was performed to measure the similarity between the patient's tumor and all available derived PDX specimens, with a median PPA over 90%, indicating a high level of retained heterogeneity within the PDX models. Lastly, 69% of models in NCI PDMR had predictive biomarkers, ranging from OncoKB level of evidence 1-4, which could be used to evaluate targeted therapeutics in preclinical studies. Conclusion: The NCI PDMR has a large and histologically diverse cancer representation. In this analysis, the PDXs exhibited genomic stability within early passages and preserved the majority of tumor heterogeneity observed in the patient specimens. NCI PDMR thus represents a valuable resource for researchers interested in preclinical drug screening or other investigations. Citation Format: Ting-Chia Chang, Biswajit Das, Li Chen, Peter I-Fan Wu, Yvonne A. Evrard, Rini Pauly, Dianne L. Newton, Shahanawaz Jiwani, Sergio Y. Alcoser, Luke H. Stockwin, Corinne E. Camalier, Tomas Forbes, Nikitha Nair, Alyssa Chapman, Lindsay Dutko, Michael Mullendore, Tara Grinnage-Pulley, Kimberly Klarmann, Sarah B. Miller, Chris A. Karlovich, Alice P. Chen, P Mickey Williams, Melinda G. Hollingshead, James H. Doroshow. Genomic landscape and stability of preclinical models in NCI's patient-derived models repository [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 6914.

Abstract 2860: High-resolution mapping of oncogenic structural changes in osteosarcoma

Abstract We have leveraged long-read and spatial sequencing modalities to identify cancer-specific oncogenic alterations for treatment of osteosarcomas. Osteosarcoma is archetypal of cancers driven by aneuploidy and structural rearrangement rather than point mutations. The functional consequences of many SVs stem from their effect on multidimensional genome organization. SVs can enable enhancer hijacking, alter boundaries of topologically associated domains (TADs), and move gene loci to different regulatory compartments to affect gene expression. SVs can also lead to the formation of extrachromosomal DNA amplicons (ecDNA), which can be megabases in size and can incorporate both genes and regulatory elements to result in substantial increases in gene transcription and intratumor heterogeneity. Complex SVs may have profound implications for prognosis and treatment in OS and other cancers yet they remain poorly understood. By incorporating long-read optical genome mapping (OGM) and chromatin conformation capture sequencing (HiC), we studied SVs in osteosarcoma with the goal of elucidating their contribution to cancer development. We used a unique panel of 11 OS patient-derived xenograft (PDX) cell lines which have been previously characterized regarding response to targeted therapies as well as genomically via whole genome (WGS), RNA (RNA-seq), and chromatin accessibility (ATAC-seq) sequencing. To understand the complex genomic reorganization that occurs in osteosarcoma, we integrated OGM and WGS data for all 11 cell lines to describe detailed genome-wide SVs including ecDNA formation. PDX lines assayed using OGM exhibited between 106 and 704 translocations each (versus zero detected in germline controls) and we identified dozens of potential ecDNA amplicons, including one amplicon which may explain exceptionally high expression of YAP1 and BIRC3 transcripts. Further, we used HiC to describe the topological environment resulting from these SVs and observed potential enhancer hijacking events affecting dozens of known oncogenes including MYC and CDK4. HiC interaction maps among six cell lines reveal genomic compartments and TAD boundaries in detail, with 4,167 unique TAD boundaries identified among six cell lines using 50kb genomic bins. Despite the observed complexity of these genomes, we note that 71% of TAD boundaries are consistent in at least four of the six HiC assayed cell lines, and 44% are present in all six lines. Changing TAD boundaries are associated with numerous SVs and/or copy number discrepancies, and are associated with genomic regions that contain genes with dysregulated RNA transcript levels. Overall, OGM and HiC modalities add considerably to our ability to detect oncogenic SVs and the genes they affect. Citation Format: Andrew Scott Clugston, Stan Leung, Eunice Fuentes, Leanne Sayles, Megan Ostrowski, Coco Wu, Christina Curtis, Zhicheng Ma, Yanding Zhao, Georgi K. Marinov, Vijay Ramani, Marcus Breese, Alejandro Sweet-Cordero. High-resolution mapping of oncogenic structural changes in osteosarcoma [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 2860.

Abstract 3390: Development of hypoxia responsive targeted polymersomes drug therapy validated using patient derived xenograft of triple negative breast cancer

Abstract Introduction: Eliminating triple-negative breast cancer (TNBC) resistance to neoadjuvant chemotherapy is a critical unmet clinical need. TNBC accounts for 20% of breast cancer and is more aggressive due to increased metastasis, high recurrence rate, and significant resistance to chemotherapy (e.g., Doxorubicin, DOX). Napabucasin (NAPA, a small organic molecule) is recognized to kill cancer stem cells by targeting the transcription factor STAT3 pathway and is currently in clinical trials. Our previous in vitro results showed significant effects with hypoxia-responsive targeted polymersomes compared to control in MDA-MB-231 and Patient-Derived Xenograft (PDX) TNBC cells. Further, we observed increased NRP-1 expression in TNBC patient-derived xenograft (PDX) cells under hypoxic (0.2% oxygen) conditions compared to normoxia (21% oxygen). Hence, we hypothesize that targeted hypoxia-responsive polymersome drug therapy would reduce the tumor growth of the PDX mouse model of triple-negative breast cancer in vivo. Methods: We have established the TNBC PDX mouse model with two major phases, initial propagation (F1-F3) and final study phase (F3-F6), for in vivo study (TNBC tumor samples received from Sanford Broadway Clinic, Fargo, IRB approved). We utilized 3-6 months old female adult NSG mice (Jackson Lab) weighing 18-25 g. PDX tumor-bearing female NSG mice were administered polymersome-encapsulated drug (doxorubicin and other groups) by intravenous injection twice a week for 4 weeks and then observed the animals for an additional week. The percentage of tumor volume growth was calculated on these treatment groups and compared to vehicle. The tumors from all the groups were excised and dissected after the treatment and fixed in 10% formalin for histological evaluation. Tumors from all the groups after treatment were stained using hematoxylin and eosin to analyze the tumor core necrosis, and the average area of necrosis was compared among all the groups. Results: The TNBC PDX mouse model treated with DOX alone and a combination of encapsulated DOX with NAPA showed significant weight loss compared to the control (over 4 weeks). DOX-alone treated mice have shown reduced tumor growth and exhibited a significant difference compared to the control group. Notably, the targeted DOX-encapsulated polymersome demonstrated a much lower tumor volume and displayed a marked difference compared to non-targeted vehicles, free-DOX, and saline. In the initial analysis, we observed a higher necrosis in the tumor of the targeted DOX-encapsulated polymersome compared to the control. Summary and Conclusion: Overall, the hypoxia-responsive targeted polymersomes showed potent antitumor activity in the novel TNBC PDX animal model. With further developments, the targeted polymersomes might have translational potential as drug carriers for treating TNBC. Citation Format: Yogaraj S Ramakrishnan, Shubhashri Ambhore, Connor Edvall, Jiyan Mohammed, Sanku Mallik, Daniel M Tuvin, Venkatachalem Sathish. Development of hypoxia responsive targeted polymersomes drug therapy validated using patient derived xenograft of triple negative breast cancer [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 3390.

Abstract 6902: Development of a stable luciferase expressing PDX-derived cell line for translational in vitro and in vivo testing

Abstract Despite much effort invested in developing novel cancer therapies, more than 90% of clinical studies fail due to toxicity or lack of efficacy in patients. This can mainly be ascribed to lack of relevant and translational preclinical models. A common model used in preclinical studies is the xenograft model using immortalized cancer cells. Cell line-based models are cost efficient and can be genetically manipulated but are often criticized for lacking translational value. A murine model with higher clinical relevance is the patient derived xenografts (PDX) model established by implanting patients’ tumor tissue onto immunodeficient mice. Knowledge of patient therapy response, mutational status and tumor heterogeneity makes it a relevant model. However, PDX models are costly, not applicable for in vitro assays or subjective to genetic manipulation. To more closely mimic in vivo tumors we have established a PDX-derived cell line (PDXc) and characterized it extensively in a head-to-head comparison to the parental PDX model. Cells were isolated from a subcutaneous (SC) glioblastoma (GBM) PDX tumor (ST146), processed into single cells and cultivated in vitro. Once the PDXc were stable over several passages the cells were re-implanted into mice. Tumor take and growth rate were evaluated against the parental PDX model and common characteristics of the model such as EFGR and Vimentin expression were determined by IHC. We furthermore generated a stable Luciferase expressing PDXc using 3rd generation lentiviral particles and implanted the cells in an intracranial (IC) model of GBM. Tumor growth was evaluated using bioluminescence imaging (BLI) and MRI. Upon multiple passages and freeze cycles the cell line (ST146c) exhibited a stable in vitro doubling time (2.6 ± 0.2 days) with a morphology like other GBM cell lines with formation of neurospheres. STR analysis confirmed a genetic identical profile to ST146. ST146c implanted into mice had similar tumor take and growth rates to the parental PDX when injected IC (>90%, Td=3 d) and SC (>75%, Td=6 d). We also showed that ST146c had more homogeneous tumor growth. Ex vivo analysis showed similar expressions of EGFR (-), Vimentin (+++) and Ki67 (++) between the models. The BLI signal obtained from luciferase expressing ST146c implanted orthotopically was correlated to tumor volume obtained by MRI. We developed a PDX cell line that preserved critical in vitro and in vivo characteristics of the PDX model such as doubling time, tumor take rate and marker expression making it feasible to use the PDXc model in future preclinical studies. This will allow in vitro screens with patient derived tumor cells. Furthermore, the expression of luciferase in the PDXc enables intracranial and metastatic implantation with tumor monitoring using BLI. This platform consisting of in vitro and in vivo PDX models could be used as a predictive translational platform for testing new cancer therapies. Citation Format: Sigrid Cold, Rikke N. Bøge, Emma Papin, Ida T. Michler, Lotte K. Kristensen, Trine B. Engel, Andreas Kjaer, Carsten H. Nielsen, Sebastian Gnosa. Development of a stable luciferase expressing PDX-derived cell line for translational in vitro and in vivo testing [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 6902.

Abstract 3358: Tribbles 1 (TRIB1) pseudokinase forms a complex with and activates Akt in GBM cells

Abstract Glioblastoma (GBM; WHO grade 4) is the most aggressive form of glioma with a dismal 5-year survival rate. The current therapies are largely ineffective and therapy resistance is commonly encountered. We have recently shown that TRIB1, a Ser/Thr pseudokinase contributes to therapeutic resistance in GBM cells by activating both ERK and Akt pathways. Here we show that, increased expression of TRIB1 contributed to RT/TMZ resistance by activating pro-survival Akt signaling resulting in increased viability of GBM cells. High level of Akt phosphorylation/activation is correlated with poor prognosis of GBM patients. Many pan Akt inhibitors have been developed which are currently in various phases of clinical trials. The three Akt isoforms (1, 2 and 3) are known to play a role in cancer during proliferation, transformation and metastasis. A previous report has shown that TRIB1 interacts with Akt1 in Drosophila and blocks its activation. In this study we show that Akt binds and forms a complex with TRIB1 in GBM cells and this interaction could be isoform and cell line specific. We utilized patient derived xenograft (PDX) GBM cell lines and established GBM cell lines in this study. Stable TRIB1 overexpressing cell lines were generated by antibiotic selection. Co-immunoprecipitation (Co-IP) was performed utilizing Anti-FLAG or anti-c-Myc magnetic agarose beads to evaluate protein-protein interactions. Western blotting was done to detect protein levels. The FLAG tagged TRIB1 deletion mutants were a generous gift from Dr. Takuro Nakamura (Division of Carcinogenesis, The Cancer Institute, Tokyo, Japan). Cells were transfected using Lipofectamine 2000 reagent. Co-IP studies showed that TRIB1 formed a complex with Akt in PDX GBM cell lines. We then transiently transfected respective TRIB1 deletion mutants lacking either N and C terminal residues in HEK 293 cells and performed Co-IP with Anti-FLAG magnetic agarose beads. We observed that all TRIB1 deletion mutants except TRIB1-ΔN2 (lacking first 160 amino acids) were able to pull down Akt. The western blot results showed that each Akt isoform had a variable protein expression across different cell lines. Co-IP studies in the PDX cell lines showed that TRIB1 interacted with all three Akt isoforms in T08-387 cells whereas TRIB1 consistently interacted with only Akt3 but not Akt1/2 in GBM30 cells that lack wild-type p53 expression. Our data suggest that TRIB1 forms a complex with Akt in PDX GBM cell lines. The potential Akt binding site on TRIB1 lies between 90-160 amino acids. TRIB1 can interact with different Akt isoforms in a cell type dependent manner thereby playing a role in their activation and consequent tumorigenic processes. Therefore, targeting TRIB1 mediated Akt activation could be considered a better therapeutic option over targeting Akt directly, which may decrease Akt’s oncogenic activities without risking the toxicity associated with available Akt- specific inhibitors. Citation Format: Karnika Singh, Chunhua Han, Heather Manring, Saikh Jaharul Haque, Arnab Chakravarti. Tribbles 1 (TRIB1) pseudokinase forms a complex with and activates Akt in GBM cells [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 3358.

Abstract 1750: Decoding breast cancer: Unraveling subtype and model differences through multi-model single-cell RNA sequencing data integration

Abstract Breast cancer's complex transcriptional landscape requires a deep understanding of sample and cell diversity to identify effective treatments. In this study, we amalgamate single-cell RNA sequencing data from breast cancer patient-derived xenografts (PDX), organoids, cell lines, patient tumors and reduction mammoplasties resulting in a comprehensive dataset of 117 samples with 506,719 total cells. These samples encompass hormone receptor positive (HR+), human epidermal growth factor receptor 2 enriched (HER2E), and triple-negative breast cancer (TNBC) subtypes. We aimed to delineate similarities and distinctions across model systems and patient samples while also exploring stratification of therapeutic drug efficacy based on subtype proportions within tumors. Mammary tumor PDXs, organoids, and established cell lines exhibited higher proliferation and lower heterogeneity observed via UMAP dimensionality reduction compared to most patient tumors or normal breast epithelium. TNBCs had elevated proliferative and pro-metastatic signatures compared to HR+ and HER2E samples. Interestingly, compared to matched PDX tumors, organoids from these same models were found to exhibit stark differences in gene expression, including upregulation of metabolically active aldo-keto reductase family genes, highlighting differences in the model systems with implications for pre-clinical drug testing. Single-cell tumor subtyping analyses with scSubtype and TNBCtype methods found that therapeutically treated samples had shifts in the proportions of cell-wise subtype annotations when compared to matched untreated samples. Similarly, patient lymph node metastasis when compared with matched primary tumors were significantly linked to decreases in Basal-like and HER2-enriched cell-wise annotations in untreated ER+ samples. In vitro assessment of anti-cancer compounds on PDX cells showed significant correlation of subtype proportion with cell viability following treatment with targeted therapeutic agents. This subtyping methodology offers a powerful tool to monitor the evolving gene expression landscape within samples and predict responses to therapeutic agents. We present here a dynamic approach to cell-wise sample annotation and a substantial multi-model dataset for use facilitating informed decision-making in preclinical research and therapeutic development. Citation Format: Julia E. Altman, Carson J. Walker, Emily K. Zboril, Nicole S. Hairr, Rachel K. Myrick, David C. Boyd, Jennifer E. Koblenski, Madhavi Puchalapalli, Bin Hu, Mikhail G. Dozmorov, Xi Chen, Yunshun Chen, Charles M. Perou, Brian D. Lehmann, Jane E. Visvader, Amy L. Olex, J. Chuck Harrell. Decoding breast cancer: Unraveling subtype and model differences through multi-model single-cell RNA sequencing data integration [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 1750.

Abstract 4272: Disruption of hyaluronan metabolism alters glioma cell proliferation by ligand dependent and independent mechanisms

Abstract Hyaluronan (HA) is the main constituent of the brain extracellular matrix and is an essential component of the glioblastoma (GBM) tumor microenvironment. The biosynthesis and catabolism of hyaluronan has multiple roles in tissue architecture and cell signaling. Dysregulation of these mechanisms is crucial in pathological processes such as cancer, inflammation or tissue remodeling. The role of HA is believed to be strongly dependent on its size (molecular weight), location, and cell receptor density and activity. HA is produced intracellularly by HA synthases (HAS1-3) and can also be catabolized endogenously by hyaluronidases (HYAL1-3).The fabrication of controlled microenvironments provided by three dimensional (3D) models helps to elucidate the role of HA signaling in GBM tumors. We exploit here the advantages of these models to understand the role of hyaluronan in the local behavior of GBM after radiation therapy and selected targeted inhibitors. We have established engineered brain tumor biomaterials based on functionalized hydrogels to monitor the response of patient-derived xenograft cell populations with different molecular signatures in combination with microfluidic devices. We have analyzed shifts in metabolism, hyaluronan secretion, as well as hyaluronan synthetic enzymes (HAS) and hyaluronidases (HYAL) activity in an array of patient derived GBM cells. We reveal that endogenous HA plays a role in mitochondrial respiration and cell proliferation in a tumor subtype dependent manner. We also show that HA fragments can enhance tumor metabolism and growth through ligand dependent and independent mechanisms. We provide bioengineered platforms and strategies to predict and stratify tumors in order to achieve more efficient combinatorial treatments targeting endogenous hyaluronan production. This work emphasizes the potential of these preclinical models to predict and accelerate cancer treatments, more relevant in malignancies with limited treatment options. Citation Format: Edward R. Neves, Joseph Mueller, Achal Anand, Kimberly Selting, Hui Xu, Roddel Remy, Brendan Harley, Sara Pedron-Haba. Disruption of hyaluronan metabolism alters glioma cell proliferation by ligand dependent and independent mechanisms [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 4272.

Targeting metastasis-initiating cancer stem cells in gastric cancer with leukaemia inhibitory factor

Gastric cancer’s (GC) bad prognosis is usually associated with metastatic spread. Invasive cancer stem cells (CSC) are considered to be the seed of GC metastasis and not all CSCs are able to initiate metastasis. Targeting these aggressive metastasis-initiating CSC (MIC) is thus vital. Leukaemia inhibitory factor (LIF) is hereby used to target Hippo pathway oncogenic members, found to be induced in GC and associated with CSC features. LIF-treated GC cell lines, patient-derived xenograft (PDX) cells and/or CSC tumourspheres underwent transcriptomics, laser microdissection-associated proteomics, 2D and 3D invasion assays and in vivo xenograft in mice blood circulation. LIFR expression was analysed on tissue microarrays from GC patients and in silico from public databases. LIF-treated cells, especially CSC, presented decreased epithelial to mesenchymal transition (EMT) phenotype and invasion capacity in vitro, and lower metastasis initiation ability in vivo. These effects involved both the Hippo and Jak/Stat pathways. Finally, GC’s high LIFR expression was associated with better clinical outcomes in patients. LIF treatment could thus represent a targeted anti-CSC strategy to fight against metastatic GC, and LIFR detection in primary tumours could constitute a potential new prognosis marker in this disease.

Abstract P14: Efficacy of FHD-286 monotherapy and combinations against Menin inhibitor sensitive and resistant AML cells

Abstract BRG1 (SMARCA4) and BRM (SMARCA2) are the core ATPase within the BAF chromatin remodeler complexes. FHD-286 (Foghorn Therapeutics) is a potent, selective, oral inhibitor of BRG1/BRM in clinical development in AML. Present studies show that FHD-286 induces marked in vitro differentiation and loss of viability in AML cell lines and patient-derived (PD) AML cells with MLLr or mutant (mt) NPM1. FHD-286 treatment concordantly reduced genome-wide ATAC-Seq and RNA-Seq peaks, with negative enrichment at the gene-sets of MYC and E2F targets, mTORC1 signaling, translation initiation/elongation and DNA replication. FHD-286 reduced the occupancy of BRG1 and H3K27Ac on the chromatin. Mass spectrometry revealed FHD-286 reduced protein levels of c-Myc (and its targets), PLK1, BCL2, PU.1 and CDK4, but increased HEXIM1, CDKN1A/1B, CEBPα and CD11b levels. CyTOF analysis in the phenotypically characterized, PD, AML stem/progenitor cells with MLL1r or mtNPM1 showed decline in the protein levels of c-Myc, PU.1, BRG1, MEF2C, PBX3, BCL2 and MCL1, but increase in cleaved PARP and caspase-3 levels. In a PD xenograft (PDX) model of MLL1r AML, monotherapy with FHD-286 (oral gavage) for 4 to 6-weeks reduced AML burden and improved survival. FHD-286 treatment also significantly inhibited the AML-initiating potential, by reducing AML burden and improving survival of the re-engrafted mice with the FHD-286-treated PDX cells. Co-treatment with FHD-286 and BET inhibitor (OTX015), Menin inhibitor (MI, SNDX-50469), decitabine or venetoclax, exerted synergistic lethality in AML cell lines and PD AML cells with MLL1r or mtNPM1. Importantly, co-treatment with FHD-286 and OTX015, SNDX-5613 (oral gavage), venetoclax or decitabine vs each drug alone significantly reduced AML burden and improved survival in the PDX models of AML cells with MLLr or with mtNPM1, without significant toxicity. Notably, FHD-286 also induced significant lethality in MI-resistant AML cell lines and PD AML cells. Through repeated shocks with LD90 dosing of MI, followed by drug washout and recovery, we have generated MLL1r (MV4-11-MITR) and mtNPM1 (OCI-AML3-MITR) AML cell lines that are tolerant/resistant (TR) to MI (without exhibiting Menin mutations) with LD50 values greater than 1 µM. A domain-specific CRISPR screen in MV4-11-MITR cells identified several druggable co-dependencies (e.g., EP300 and MOZ) and co-enrichments (SMARCA4, CREBBP and BRD4) with MI. Accordingly, co-treatment with FHD-286 and OTX015, SNDX-50469 or CBP/p300 inhibitor GNE781 exerted synergistic lethality in MV4-11-MITR and OCI-AML3-MITR cells as well as in PD MITR AML cells with MLL1r or mtNPM1. FHD-286 and OTX015 or SNDX-5613 treatment also reduced AML burden in mice bearing OCI-AML3-MITR xenografts. These findings demonstrate pre-clinical efficacy of FHD-286-based rational combinations and underscore their promise against MI-sensitive or resistant AML with MLL1r or mtNPM1. Citation Format: Warren C Fiskus, Jessica Piel, Murphy Hentemann, Mike Collins, Christopher P Mill, Branko Cuglievan, Courtney D DiNardo, Kapil N Bhalla. Efficacy of FHD-286 monotherapy and combinations against Menin inhibitor sensitive and resistant AML cells [abstract]. In: Proceedings of the Blood Cancer Discovery Symposium; 2024 Mar 4-6; Boston, MA. Philadelphia (PA): AACR; Blood Cancer Discov 2024;5(2_Suppl):Abstract nr P14.

Targeting Wnt signaling for improved glioma immunotherapy.

Despite aggressive standard-of-care therapy, including surgery, radiation, and chemotherapy, glioblastoma recurrence is almost inevitable and uniformly lethal. Activation of glioma-intrinsic Wnt/β-catenin signaling is associated with a poor prognosis and the proliferation of glioma stem-like cells, leading to malignant transformation and tumor progression. Impressive results in a subset of cancers have been obtained using immunotherapies including anti-CTLA4, anti-PD-1, and anti-PD-L1 or chimeric antigen receptor (CAR) T cell therapies. However, the heterogeneity of tumors, low mutational burden, single antigen targeting, and associated antigen escape contribute to non-responsiveness and potential tumor recurrence despite these therapeutic efforts. In the current study, we determined the effects of the small molecule, highly specific Wnt/CBP (CREB Binding Protein)/β-catenin antagonist ICG-001, on glioma tumor cells and the tumor microenvironment (TME)-including its effect on immune cell infiltration, blood vessel decompression, and metabolic changes. Using multiple glioma patient-derived xenografts cell lines and murine tumors (GL261, K-Luc), we demonstrated in vitro cytostatic effects and a switch from proliferation to differentiation after treatment with ICG-001. In these glioma cell lines, we further demonstrated that ICG-001 downregulated the CBP/β-catenin target gene Survivin/BIRC5-a hallmark of Wnt/CBP/β-catenin inhibition. We found that in a syngeneic mouse model of glioma (K-luc), ICG-001 treatment enhanced tumor infiltration by CD3+ and CD8+ cells with increased expression of the vascular endothelial marker CD31 (PECAM-1). We also observed differential gene expression and induced immune cell infiltration in tumors pretreated with ICG-001 and then treated with CAR T cells as compared with single treatment groups or when ICG-001 treatment was administered after CAR T cell therapy. We conclude that specific Wnt/CBP/β-catenin antagonism results in pleotropic changes in the glioma TME, including glioma stem cell differentiation, modulation of the stroma, and immune cell activation and recruitment, thereby suggesting a possible role for enhancing immunotherapy in glioma patients.

Bone mimetic environments support engineering, propagation, and analysis of therapeutic response of patient-derived cells, ex vivo and in vivo

Bone metastases are the most common milestone in the lethal progression of prostate cancer and prominent in a substantial portion of renal malignancies. Interactions between cancer and bone host cells have emerged as drivers of both disease progression and therapeutic resistance. To best understand these central host-epithelial cell interactions, biologically relevant preclinical models are required. To achieve this goal, we here established and characterized tissue-engineered bone mimetic environments (BME) capable of supporting the growth of patient-derived xenograft (PDX) cells, ex vivo and in vivo. The BME consisted of a polycaprolactone (PCL) scaffold colonized by human mesenchymal stem cells (hMSCs) differentiated into osteoblasts. PDX-derived cells were isolated from bone metastatic prostate or renal tumors, engineered to express GFP or luciferase and seeded onto the BMEs. BMEs supported the growth and therapy response of PDX-derived cells, ex vivo. Additionally, BMEs survived after in vivo implantation and further sustained the growth of PDX-derived cells, their serial transplant, and their application to study the response to treatment. Taken together, this demonstrates the utility of BMEs in combination with patient-derived cells, both ex vivo and in vivo. Statement of significanceOur tissue-engineered BME supported the growth of patient-derived cells and proved useful to monitor the therapy response, both ex vivo and in vivo. This approach has the potential to enable co-clinical strategies to monitor bone metastatic tumor progression and therapy response, including identification and prioritization of new targets for patient treatment.

FDA-approved disulfiram as a novel treatment for aggressive leukemia

Acute leukemia continues to be a major cause of death from disease worldwide and current chemotherapeutic agents are associated with significant morbidity in survivors. While better and safer treatments for acute leukemia are urgently needed, standard drug development pipelines are lengthy and drug repurposing therefore provides a promising approach. Our previous evaluation of FDA-approved drugs for their antileukemic activity identified disulfiram, used for the treatment of alcoholism, as a candidate hit compound. This study assessed the biological effects of disulfiram on leukemia cells and evaluated its potential as a treatment strategy. We found that disulfiram inhibits the viability of a diverse panel of acute lymphoblastic and myeloid leukemia cell lines (n = 16) and patient-derived xenograft cells from patients with poor outcome and treatment-resistant disease (n = 15). The drug induced oxidative stress and apoptosis in leukemia cells within hours of treatment and was able to potentiate the effects of daunorubicin, etoposide, topotecan, cytarabine, and mitoxantrone chemotherapy. Upon combining disulfiram with auranofin, a drug approved for the treatment of rheumatoid arthritis that was previously shown to exert antileukemic effects, strong and consistent synergy was observed across a diverse panel of acute leukemia cell lines, the mechanism of which was based on enhanced ROS induction. Acute leukemia cells were more sensitive to the cytotoxic activity of disulfiram than solid cancer cell lines and non-malignant cells. While disulfiram is currently under investigation in clinical trials for solid cancers, this study provides evidence for the potential of disulfiram for acute leukemia treatment.Key messagesDisulfiram induces rapid apoptosis in leukemia cells by boosting oxidative stress.Disulfiram inhibits leukemia cell growth more potently than solid cancer cell growth.Disulfiram can enhance the antileukemic efficacy of chemotherapies.Disulfiram strongly synergises with auranofin in killing acute leukemia cells by ROS induction.We propose testing of disulfiram in clinical trial for patients with acute leukemia.

From the identification of actionable molecular targets to the generation of faithful neuroblastoma patient-derived preclinical models

BackgroundNeuroblastoma (NB) represents the most frequent and aggressive form of extracranial solid tumor of infants. Although the overall survival of patients with NB has improved in the last years, more than 50% of high-risk patients still undergo a relapse. Thus, in the era of precision/personalized medicine, the need for high-risk NB patient-specific therapies is urgent.MethodsWithin the PeRsonalizEd Medicine (PREME) program, patient-derived NB tumors and bone marrow (BM)-infiltrating NB cells, derived from either iliac crests or tumor bone lesions, underwent to histological and to flow cytometry immunophenotyping, respectively. BM samples containing a NB cells infiltration from 1 to 50 percent, underwent to a subsequent NB cells enrichment using immune-magnetic manipulation. Then, NB samples were used for the identification of actionable targets and for the generation of 3D/tumor-spheres and Patient-Derived Xenografts (PDX) and Cell PDX (CPDX) preclinical models.ResultsEighty-four percent of NB-patients showed potentially therapeutically targetable somatic alterations (including point mutations, copy number variations and mRNA over-expression). Sixty-six percent of samples showed alterations, graded as “very high priority”, that are validated to be directly targetable by an approved drug or an investigational agent. A molecular targeted therapy was applied for four patients, while a genetic counseling was suggested to two patients having one pathogenic germline variant in known cancer predisposition genes. Out of eleven samples implanted in mice, five gave rise to (C)PDX, all preserved in a local PDX Bio-bank. Interestingly, comparing all molecular alterations and histological and immunophenotypic features among the original patient’s tumors and PDX/CPDX up to second generation, a high grade of similarity was observed. Notably, also 3D models conserved immunophenotypic features and molecular alterations of the original tumors.ConclusionsPREME confirms the possibility of identifying targetable genomic alterations in NB, indeed, a molecular targeted therapy was applied to four NB patients. PREME paves the way to the creation of clinically relevant repositories of faithful patient-derived (C)PDX and 3D models, on which testing precision, NB standard-of-care and experimental medicines.

Targeting G9a/DNMT1 methyltransferase activity impedes IGF2-mediated survival in hepatoblastoma.

As the variable clinical outcome of patients with hepatoblastoma (HB) cannot be explained by genetics alone, the identification of drugs with the potential to effectively reverse epigenetic alterations is a promising approach to overcome poor therapy response. The gene ubiquitin like with PHD and ring finger domains 1 (UHRF1) represents an encouraging epigenetic target due to its regulatory function in both DNA methylation and histone modifications and its clinical relevance in HB. Patient-derived xenograft in vitro and in vivo models were used to study drug response. The mechanistic basis of CM-272 treatment was elucidated using RNA sequencing and western blot experiments. We validated in comprehensive data sets that UHRF1 is highly expressed in HB and associated with poor outcomes. The simultaneous pharmacological targeting of UHRF1-dependent DNA methylation and histone H3 methylation by the dual inhibitor CM-272 identified a selective impact on HB patient-derived xenograft cell viability while leaving healthy fibroblasts unaffected. RNA sequencing revealed downregulation of the IGF2-activated survival pathway as the main mode of action of CM-272 treatment, subsequently leading to loss of proliferation, hindered colony formation capability, reduced spheroid growth, decreased migration potential, and ultimately, induction of apoptosis in HB cells. Importantly, drug response depended on the level of IGF2 expression, and combination assays showed a strong synergistic effect of CM-272 with cisplatin. Preclinical testing of CM-272 in a transplanted patient-derived xenograft model proved its efficacy but also uncovered side effects presumably caused by its strong antitumor effect in IGF2-driven tumors. The inhibition of UHRF1-associated epigenetic traces, such as IGF2-mediated survival, is an attractive approach to treat high-risk HB, especially when combined with the standard-of-care therapeutic cisplatin.

New Function Annotation of PROSER2 in Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis due to the absence of diagnostic markers and molecular targets. Here, we took an unconventional approach to identify new molecular targets for pancreatic cancer. We chose uncharacterized protein evidence level 1 without function annotation from extensive proteomic research on pancreatic cancer and focused on proline and serine-rich 2 (PROSER2), which ranked high in the cell membrane and cytoplasm. In our study using cell lines and patient-derived orthotopic xenograft cells, PROSER2 exhibited a higher expression in cells derived from primary tumors than in those from metastatic tissues. PROSER2 was localized in the cell membrane and cytosol by immunocytochemistry. PROSER2 overexpression significantly reduced the metastatic ability of cancer cells, whereas its suppression had the opposite effect. Proteomic analysis revealed that PROSER2 interacts with STK25 and PDCD10, and their binding was confirmed by immunoprecipitation and immunocytochemistry. STK25 knockdown enhanced metastasis by decreasing p-AMPK levels, whereas PROSER2-overexpressing cells increased the level of p-AMPK, indicating that PROSER2 suppresses invasion via the AMPK pathway by interacting with STK25. This is the first demonstration of the novel role of PROSER2 in antagonizing tumor progression via the STK25-AMPK pathway in PDAC. LC-MS/MS data are available at MassIVE (MSV000092953) and ProteomeXchange (PXD045646).

Abstract B070: Histone deacetylation inhibition promotes bi-directional subtype switch in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a dismal disease with 5-year survival of just 11%. Recent large-scale transcriptomic studies have identified two prognostically relevant neoplastic tumor subtypes, i.e. the well-differentiated classical (CLA) subtype with better prognosis, characterized by epithelial gene expression, as well as the dedifferentiated, invasive basal-like (BL) subtype, which displays mesenchymal stemness-related gene signatures. These subtypes have shown to be highly plastic and responsive to extrinsic signals, e.g. from the microenvironment or treatment-induced. Here, we investigate master transcription factor networks governing lineage determination in the different subtypes and the role of histone deacetylation (HDAC) co-regulators in their maintenance. We utilized established, subtype-defined PDAC cell lines in vitro and in orthotopic transplantation models to determine subtype plasticity in response to HDAC inhibition by the pan-HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). By integration of RNA-seq, ATAC-seq as well as HiChIP for the activating mark histone 3 lysine 27 acetylation (H3K27ac), we show that the subtype-dependent chromatin organization and regulatory networks can be influenced by pharmacological inhibition of chromatin remodelers, in turn promoting changes in transcription of lineage-determining factors. Targeting these transcription factor networks by HDAC inhibition can lead both to a favorable switch from BL to CLA identity, as well as a detrimental CLA to BL switch. Functional assay such as trans-well invasion further supported the changes in subtype identity following SAHA treatment. This bi-directional subtype switch was additionally validated in patient-derived xenograft cell lines. Together, our findings highlight the importance of understanding the underlying transcriptional and epigenetic mechanisms of the pancreatic cancer subtypes, as they may exhibit opposing responses to targeted therapies. Citation Format: Lukas Klein, Mengyu Tu, Eva K. Schmitt, Frederike Penz, Athanasia Mizi, Stefan Küffer, Elisabeth Hessmann, Argyris Papantonis, Volker Ellenrieder, Shiv K. Singh. Histone deacetylation inhibition promotes bi-directional subtype switch in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B070.