Patient-Derived Cancer Models Research Articles

Modeling epithelial-mesenchymal transition in patient-derived breast cancer organoids.

Cellular plasticity is enhanced by dedifferentiation processes such as epithelial-mesenchymal transition (EMT). The dynamic and transient nature of EMT-like processes challenges the investigation of cell plasticity in patient-derived breast cancer models. Here, we utilized patient-derived organoids (PDOs) as a model to study the susceptibility of primary breast cancer cells to EMT. Upon induction with TGF-β, PDOs exhibited EMT-like features, including morphological changes, E-cadherin downregulation and cytoskeletal reorganization, leading to an invasive phenotype. Image analysis and the integration of deep learning algorithms enabled the implantation of microscopy-based quantifications demonstrating repetitive results between organoid lines from different breast cancer patients. Interestingly, epithelial plasticity was also expressed in terms of alterations in luminal and myoepithelial distribution upon TGF-β induction. The effective modeling of dynamic processes such as EMT in organoids and their characteristic spatial diversity highlight their potential to advance research on cancer cell plasticity in cancer patients.

280 (PB268): Response to precision-guided treatments in patient-derived models of metastatic breast cancer

280 (PB268): Response to precision-guided treatments in patient-derived models of metastatic breast cancer

283 (PB271): CancerModels.Org - an open global cancer research platform for patient-derived cancer models.

283 (PB271): CancerModels.Org - an open global cancer research platform for patient-derived cancer models.

Anti-tissue factor antibody conjugated with monomethyl auristatin E or deruxtecan in pancreatic cancer models.

Antibody-drug conjugates (ADCs) have been recognized as a promising class of cancer therapeutics. Tissue factor (TF), an initiator of the blood coagulation pathway, has been investigated regarding its relationship with cancer, and several preclinical and clinical studies have presented data on anti-TF ADCs, including tisotumab vedotin, which was approved in 2021. However, the feasibility of other payloads in the design of anti-TF ADCs is still unclear because no reports have compared payloads with different cytotoxic mechanisms. For ADCs targeting other antigens, such as Her2, optimizing the payload is also an important issue in order to improve invivo efficacy. In this study, we prepared humanized anti-TF Ab (clone.1084) conjugated with monomethyl auristatin E (MMAE) or deruxtecan (DXd), and evaluated the efficacy in several cell line- and patient-derived xenograft models of pancreatic cancer. As a result, optimizing the drug / Ab ratio was necessary for each payload in order to prevent pharmacokinetic deterioration and maximize delivery efficiency. In addition, MMAE-conjugated anti-TF ADC showed higher antitumor effects in tumors with strong and homogeneous TF expression, while DXd-conjugated anti-TF ADC was more effective in tumors with weak and heterogeneous TF expression. Analysis of a pancreatic cancer tissue array showed weak and heterogeneous TF expression in most TF-positive specimens, indicating that the response rate to pancreatic cancer might be higher for DXd- than MMAE-conjugated anti-TF ADC. Nevertheless, our findings indicated that optimizing the ADC payloads individually in each patient could maximize the potential of ADC therapeutics.

Single-cell analysis of breast cancer metastasis reveals epithelial-mesenchymal plasticity signatures associated with poor outcomes.

Metastasis is the leading cause of cancer-related deaths. It is unclear how intratumor heterogeneity (ITH) contributes to metastasis and how metastatic cells adapt to distant tissue environments. The study of these adaptations is challenged by the limited access to patient material and a lack of experimental models that appropriately recapitulate ITH. To investigate metastatic cell adaptations and the contribution of ITH to metastasis, we analyzed single-cell transcriptomes of matched primary tumors and metastases from patient-derived xenograft models of breast cancer. We found profound transcriptional differences between the primary tumor and metastatic cells. Primary tumors upregulated several metabolic genes, whereas motility pathway genes were upregulated in micrometastases, and stress response signaling was upregulated during progression. Additionally, we identified primary tumor gene signatures that were associated with increased metastatic potential and correlated with patient outcomes. Immune-regulatory control pathways were enriched in poorly metastatic primary tumors, whereas genes involved in epithelial-mesenchymal transition were upregulated in highly metastatic tumors. We found that ITH was dominated by epithelial-mesenchymal plasticity (EMP), which presented as a dynamic continuum with intermediate EMP cell states characterized by specific genes such as CRYAB and S100A2. Elevated expression of an intermediate EMP signature correlated with worse patient outcomes. Our findings identified inhibition of the intermediate EMP cell state as a potential therapeutic target to block metastasis.

Developing Patient-Derived 3D-Bioprinting models of pancreatic cancer

IntroductionPancreatic cancer (PC) remains a challenging malignancy, and adjuvant chemotherapy is critical in improving patient survival post-surgery. However, the intrinsic heterogeneity of PC necessitates personalized treatment strategies, highlighting the need for reliable preclinical models. ObjectivesThis study aimed to develop novel patient-derived preclinical PC models using three-dimensional bioprinting (3DP) technology. MethodsPatient-derived PC models were established using 3DP technology. Genomic and histological analyses were performed to characterize these models and compare them with corresponding patient tissues. Chemotherapeutic drug sensitivity tests were conducted on the PC 3DP models, and correlations with clinical outcomes were analyzed. ResultsThe study successfully established PC 3DP models with a modeling success rate of 86.96%. These models preserved genomic and histological features consistent with patient tissues. Drug sensitivity testing revealed significant heterogeneity among PC 3DP models, mirroring clinical variability, and potential correlations with clinical outcomes. ConclusionThe PC 3DP models demonstrated their utility as reliable preclinical tools, retaining key genomic and histological characteristics. Importantly, drug sensitivity profiles in these models showed potential correlations with clinical outcomes, indicating their promise in customizing treatment strategies and predicting patient prognoses. Further validation with larger patient cohorts is warranted to confirm their potential clinical utility.

Near Infrared-Fluorescent Dinuclear Iridium(III) Nanoparticles for Immunogenic Sonodynamic Therapy.

Dinuclear iridium(III) complexes activated by light-inducible spatiotemporal control are emerging as promising candidates for cancer therapy. However, broader applications of current light-activated dinuclear iridium(III) complexes are limited by the ineffective tissue penetration and undesirable feedback on guidance activation. Here, an ultrasound (US) triggered near infrared-fluorescent dinuclear iridium(III) nanoparticle, NanoIr, is first reported to precisely and spatiotemporally inhibit tumor growth. It is demonstrated that reactive oxygen species can be generated by NanoIr upon exposure to US irradiation (NanoIr + US), thereby inducing immunogenic cell death. When combined with cisplatin, NanoIr + US elicits synergistic effects in patient-derived tumor xenograft mice models of ovarian cancer. This work first provides a design of dinuclear iridium(III) nanoparticles for immunogenic sonodynamic therapy.

Stable isotope-resolved metabolomics analyses of metabolic phenotypes reveal variable glutamine metabolism in different patient-derived models of non-small cell lung cancer from a single patient.

Stable isotope tracers have been increasingly used in preclinical cancer model systems, including cell culture and mouse xenografts, to probe the altered metabolism of a variety of cancers, such as accelerated glycolysis and glutaminolysis and generation of oncometabolites. Comparatively little has been reported on the fidelity of the different preclinical model systems in recapitulating the aberrant metabolism of tumors. We have been developing several different experimental model systems for systems biochemistry analyses of non-small cell lung cancer (NSCLC1) using patient-derived tissues to evaluate appropriate models for metabolic and phenotypic analyses. To address the issue of fidelity, we have carried out a detailed Stable Isotope-Resolved Metabolomics study of freshly resected tissue slices, mouse patient derived xenografts (PDXs), and cells derived from a single patient using both 13C6-glucose and 13C5,15N2-glutamine tracers. Although we found similar glucose metabolism in the three models, glutamine utilization was markedly higher in the isolated cell culture and in cell culture-derived xenografts compared with the primary cancer tissue or direct tissue xenografts (PDX). This suggests that caution is needed in interpreting cancer biochemistry using patient-derived cancer cells in vitro or in xenografts, even at very early passage, and that direct analysis of patient derived tissue slices provides the optimal model for ex vivo metabolomics. Further research is needed to determine the generality of these observations.

CDKL3 is a targetable regulator of cell cycle progression in cancers.

Cell cycle regulation is largely abnormal in cancers. Molecular understanding and therapeutic targeting of the aberrant cell cycle are essential. Here, we identified that an underappreciated serine/threonine kinase, cyclin-dependent kinase-like 3 (CDKL3), crucially drives rapid cell cycle progression and cell growth in cancers. With regard to mechanism, CDKL3 localizes in the nucleus and associates with specific cyclin to directly phosphorylate retinoblastoma (Rb) for quiescence exit. In parallel, CDKL3 prevents the ubiquitin-proteasomal degradation of cyclin-dependent kinase 4 (CDK4) by direct phosphorylation on T172 to sustain G1 phase advancement. The crucial function of CDKL3 in cancers was demonstrated both in vitro and in vivo. We also designed, synthesized, and characterized a first-in-class CDKL3-specific inhibitor, HZ1. HZ1 exhibits greater potency than CDK4/6 inhibitor in pan-cancer treatment by causing cell cycle arrest and overcomes acquired resistance to CDK4/6 inhibitor. In particular, CDKL3 has significant clinical relevance in colon cancer, and the effectiveness of HZ1 was demonstrated by murine and patient-derived cancer models. Collectively, this work presents an integrated paradigm of cancer cell cycle regulation and suggests CDKL3 targeting as a feasible approach in cancer treatment.

Efficacy of fadraciclib (CYC065), a novel dual CDK2/9 inhibitor, on patient-derived models of colorectal cancer.

3596 Background: Colorectal cancer (CRC) is the third most common type of cancer among adults in the United States. Given the heterogeneous nature of the disease and the limited number of treatments available, there is an unmet need to identify new therapeutic vulnerabilities for advanced CRC. One promising approach is targeting of cyclin dependent kinases (CDKs). In our current study, we sought to understand the potential efficacy of fadraciclib (CYC065), a novel dual CDK 2/9 inhibitor, as a novel treatment for metastatic CRC. Methods: Eighteen CRC patient-derived organoids (PDOs) were generated from patients undergoing biopsy or resection for their primary or metastatic CRC under an IRB approved protocol at Duke University. IHC and H&E staining were first performed on the established PDOs to confirm the diagnosis of CRC. PDOs were treated with standard of care chemotherapy (oxaliplatin, irinotecan (SN38) and 5-Flurouracil), CDK4/6 inhibitor palbociclib, and fadraciclib (CYC065). All drugs were used in doses ranging from 6.4nM to 100µM, and drug sensitivities were determined using Cell-Titer Glo (CTG) 72 hours after treatment. Subsequently, three matching PDXs were generated for in vivo validation and treated with fadraciclib (CYC065) via oral gavage at a dose of 25 mg/kg BID five days a week for two weeks. Target validation for CDK2/9 inhibition was performed via western blotting, cell cycle arrest was determined via flow cytometry, and killing by anaphase catastrophe was determined by immunofluorescence staining. Results: CRC PDOs were more sensitive to fadraciclib (CYC065) than chemotherapy and palbociclib, with IC50 values lower than chemotherapy or palbociclib (2.65±3.92µM for fadraciclib (CYC065) vs. 29.92±41.98µM for chemotherapy (P<0.05) or palbociclib (12.33±9.87µM)). Subsequently, we validated our findings in vivo using 3 matched PDX showing significant tumor growth inhibition (TGI) with fadraciclib (CYC065) compared to control (p<0.05) without serious adverse effects. We showed that fadraciclib (CYC065) induces G2/M cell cycle arrest, resulting in anaphase catastrophe as evident by the presence of multipolar mitosis in fadraciclib (CYC065)-treated cells. CDK2/9 inhibition leads to downregulation of c-Myc levels and upregulation of apoptosis induction as a second mechanism of action for this drug. Conclusions: Our data using both in vitro and in vivo patient-derived models support further exploration of fadraciclib (CYC065) has a potential therapy for advanced CRC. CDK2/9 inhibition impacts multiple critical pathways involved in transcription, mitosis and apoptosis. Further studies will be needed to reveal molecular biomarkers of sensitivity and resistance to this novel agent.

Creation and Validation of Patient-Derived Cancer Model Using Peritoneal and Pleural Effusion in Patients with Advanced Ovarian Cancer: An Early Experience.

Background: The application of personalized cancer treatment based on genetic information and surgical samples has begun in the field of cancer medicine. However, a biopsy may be painful for patients with advanced diseases that do not qualify for surgical resection. Patient-derived xenografts (PDXs) are cancer models in which patient samples are transplanted into immunodeficient mice. PDXs are expected to be useful for personalized medicine. The aim of this study was to establish a PDX from body fluid (PDX-BF), such as peritoneal and pleural effusion samples, to provide personalized medicine without surgery. Methods: PDXs-BF were created from patients with ovarian cancer who had positive cytology findings based on peritoneal and pleural effusion samples. PDXs were also prepared from each primary tumor. The pathological findings based on immunohistochemistry were compared between the primary tumor, PDX, and PDX-BF. Further, genomic profiles and gene expression were evaluated using DNA and RNA sequencing to compare primary tumors, PDXs, and PDX-BF. Results: Among the 15 patients, PDX-BF was established for 8 patients (5 high-grade serous carcinoma, 1 carcinosarcoma, 1 low-grade serous carcinoma, and 1 clear cell carcinoma); the success rate was 53%. Histologically, PDXs-BF have features similar to those of primary tumors and PDXs. In particular, PDXs-BF had similar gene mutations and expression patterns to primary tumors and PDXs. Conclusions: PDX-BF reproduced primary tumors in terms of pathological features and genomic profiles, including gene mutation and expression. Thus, PDX-BF may be a potential alternative to surgical resection for patients with advanced disease.

Focal adhesion kinase-YAP signaling axis drives drug-tolerant persister cells and residual disease in lung cancer

Targeted therapy is effective in many tumor types including lung cancer, the leading cause of cancer mortality. Paradigm defining examples are targeted therapies directed against non-small cell lung cancer (NSCLC) subtypes with oncogenic alterations in EGFR, ALK and KRAS. The success of targeted therapy is limited by drug-tolerant persister cells (DTPs) which withstand and adapt to treatment and comprise the residual disease state that is typical during treatment with clinical targeted therapies. Here, we integrate studies in patient-derived and immunocompetent lung cancer models and clinical specimens obtained from patients on targeted therapy to uncover a focal adhesion kinase (FAK)-YAP signaling axis that promotes residual disease during oncogenic EGFR-, ALK-, and KRAS-targeted therapies. FAK-YAP signaling inhibition combined with the primary targeted therapy suppressed residual drug-tolerant cells and enhanced tumor responses. This study unveils a FAK-YAP signaling module that promotes residual disease in lung cancer and mechanism-based therapeutic strategies to improve tumor response.

Abstract PO5-14-06: Transcriptomics-based drug screening in 3D ex vivo patient-derived breast cancer model and patient biopsy for personalized therapy

Abstract Breast cancer is a leading cause of cancer-related mortality for women worldwide. Hormone receptor-positive (HR+) breast tumors, which represent 70% of all breast cancer cases, are treated with endocrine therapy. However, not all patients benefit from this treatment regimen because of patient-to-patient variation. Therefore, high throughput drug screening system is warranted to enable personalized medicine. Patient-derived organoids, which serve as a screening platform, lose their hormone receptors and response upon ex vivo culturing, and may not be adequate models for HR+ breast tumors. Moreover, unidentified biological components in the widely-used basement membrane matrix, Matrigel, result in high batch-to-batch variations and poor reproducibility in organoid cultures. Here, we propose a hydrogel-based 3D ex vivo model with defined structural and chemical properties to test hormone and drug sensitivity of HR+ breast tumors from patient-derived xenografts (PDXs) and patient tumor biopsies using microfluidics. Our data demonstrate the feasibility of this model to preserve cell proliferation and hormone receptor expression over 7 days. We also demonstrate that responses to hormones and FDA-approved drugs are faithfully maintained in this model. Finally, to establish a high throughput hormone and drug testing workflow with transcriptomic readout, we multiplexed barcoded- and drug-treated tumor samples in a single experiment with bulk RNA-sequencing. Our preliminary data demonstrate patient-specific responses to hormones and drugs that correspond to patient genetic mutation profiles, treatment history, disease stages and subtypes. This platform also enables testing of drugs in clinical trials that shows promising therapeutic outcomes for breast cancer, such as CDK4/6i, AKTi, PARPi, mTORi and their combination with endocrine therapy, thanks to the high throughput of the screening system and the low consumption of patient-derived or patient tissue. Given the capability of combining this physiologically-relevant 3D ex vivo model with RNA-seq for HR+ breast tumors, this platform holds potential for high throughput compound testing and transcriptomic profiling of patient biopsies for personalized medicine. Citation Format: Yueyun Zhang, Carlos Henrique Venturi Ronchi, Giovanna Ambrosini, Yuanlong Liu, Patrick Aouad, Daria Matvienko, Christoph Merten, Cathrin Brisken. Transcriptomics-based drug screening in 3D ex vivo patient-derived breast cancer model and patient biopsy for personalized therapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-14-06.

Patient-derived castration-resistant prostate cancer model revealed CTBP2 upregulation mediated by OCT1 and androgen receptor

BackgroundProstate cancer is dependent on androgen receptor (AR) signaling, and androgen deprivation therapy (ADT) has proven effective in targeting prostate cancer. However, castration-resistant prostate cancer (CRPC) eventually emerges. AR signaling inhibitors (ARSI) have been also used, but resistance to these agents develops due to genetic AR alterations and epigenetic dysregulation.MethodsIn this study, we investigated the role of OCT1, a member of the OCT family, in an AR-positive CRPC patient-derived xenograft established from a patient with resistance to ARSI and chemotherapy. We conducted a genome-wide analysis chromatin immunoprecipitation followed by sequencing and bioinformatic analyses using public database.ResultsGenome-wide analysis of OCT1 target genes in PDX 201.1 A revealed distinct OCT1 binding sites compared to treatment-naïve cells. Bioinformatic analyses revealed that OCT1-regulated genes were associated with cell migration and immune system regulation. In particular, C-terminal Binding Protein 2 (CTBP2), an OCT1/AR target gene, was correlated with poor prognosis and immunosuppressive effects in the tumor microenvironment. Metascape revealed that CTBP2 knockdown affects genes related to the immune response to bacteria. Furthermore, TISIDB analysis suggested the relationship between CTBP2 expression and immune cell infiltration in prostate cancer, suggesting that it may contribute to immune evasion in CRPC.ConclusionsOur findings shed light on the genome-wide network of OCT1 and AR in AR-positive CRPC and highlight the potential role of CTBP2 in immune response and tumor progression. Targeting CTBP2 may represent a promising therapeutic approach for aggressive AR-positive CRPC. Further validation will be required to explore novel therapeutic strategies for CRPC management.

A Path to Persistence after EGFR Inhibition.

Residual cancer cells persist even after targeted therapies, serving as a reservoir for the subsequent acquisition of genetic alterations that lead to acquired drug resistance and tumor relapse. These initial drug-tolerant persisters (DTP) are phenotypically heterogenous with transient phenotypes attributed to epigenetic, metabolic, and cell-cycle changes. DTPs are responsible for the inevitable relapse seen in EGFR-mutant non-small cell lung cancer (NSCLC) despite high initial response to tyrosine kinase inhibitor (TKI) treatment. While past in vitro studies identified diverse drivers of drug-tolerant persistence to EGFR TKIs in NSCLC, the resultant phenotypic plasticity is not well understood and in vivo models of persistence are lacking. In this issue of Cancer Research, Hu and colleagues used patient-derived xenograft models of EGFR-mutant lung cancer treated with the third-generation TKI osimertinib to investigate mechanisms of persistence at the time of maximal response. Using bulk and single-cell RNA sequencing, the authors identified a DTP transcriptional cluster mediated by the key neuroendocrine lineage transcription factor ASCL1, which triggers an epithelial-to-mesenchymal transition transcriptional program. ASCL1 overexpression increased osimertinib tolerance in vitro as well, apparently independent of its role in neuroendocrine differentiation. Interestingly, the ability of ASCL1 to induce persistence was context dependent as this occurred only in epigenetically permissive cells. Overall, these findings contribute to our understanding of DTP heterogeneity seen after osimertinib treatment and provide insights into potential therapeutic targets. See related article by Hu et al., p. 1303.

Abstract LB053: A novel BRAF-specific allosteric inhibitor that effectively targets acquired RAFi-resistant BRAF(V600E) cancers and RAS-mutated cancers in vitro and in vivo

Abstract Targeting hyperactive RAS-RAF-MEK-ERK signaling for treating cancers has achieved a promising outcomes, and a number of RAS/RAF inhibitors have been applied to clinical cancer treatment. However, these inhibitors have only a short-term efficacy and their effectiveness is abrogated by acquired drug resistance in less than one year. For those resistant/refractory RAS/RAF-mutated cancers, there’s no effective therapeutics available in clinic. In this study, we developed a novel BRAF-specific inhibitor that docks on an allosteric site on BRAF kinase domain. This inhibitor effectively killed both primary and drug-resistant cancer cell lines with RAS mutation or BRAF(V600E) mutation in vitro and inhibited the growth of xenografted cancers derived from these cell lines in vivo without apparent toxicity. Mechanistically, we found that although this inhibitor blocked the catalytic activity of BRAF in vitro kinase assay, it triggered a super high ERK signaling through improving BRAF/CRAF heterodimerization and hence induced cellular apoptosis of cancer cells with RAS mutation or BRAF(V600E) mutation. Surprisingly, there’s no drug resistance occurring when treating cancer cells with RAS mutation or BRAF(V600E) mutation at a low concentration. To further evaluate the efficacy of this BRAF against RAS/RAF-mutated cancers in vivo, we constructed a series of pancreatic patient-derived xenograft cancer models with Kras G12D or G12V mutations, and found that our BRAF inhibitor exhibited a comparable or much better efficacy than Kras G12D-specific inhibitor on theses PDX models. Altogether, our data indicated that our BRAF-specific allosteric inhibitor may serve as a good therapeutic drug for treating BRAF(V600E)/RAS- cancers, particularly those resistant/refractory cancers, though it still need further evaluations via clinical trials. Citation Format: Jiancheng Hu. A novel BRAF-specific allosteric inhibitor that effectively targets acquired RAFi-resistant BRAF(V600E) cancers and RAS-mutated cancers in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB053.

A Stem-like Patient-Derived Ovarian Cancer Model of Platinum Resistance Reveals Dissociation of Stemness and Resistance.

To understand chemoresistance in the context of cancer stem cells (CSC), a cisplatin resistance model was developed using a high-grade serous ovarian cancer patient-derived, cisplatin-sensitive sample, PDX4. As a molecular subtype-specific stem-like cell line, PDX4 was selected for its representative features, including its histopathological and BRCA2 mutation status, and exposed to cisplatin in vitro. In the cisplatin-resistant cells, transcriptomics were carried out, and cell morphology, protein expression, and functional status were characterized. Additionally, potential signaling pathways involved in cisplatin resistance were explored. Our findings reveal the presence of distinct molecular signatures and phenotypic changes in cisplatin-resistant PDX4 compared to their sensitive counterparts. Surprisingly, we observed that chemoresistance was not inherently linked with increased stemness. In fact, although resistant cells expressed a combination of EMT and stemness markers, functional assays revealed that they were less proliferative, migratory, and clonogenic-features indicative of an underlying complex mechanism for cell survival. Furthermore, DNA damage tolerance and cellular stress management pathways were enriched. This novel, syngeneic model provides a valuable platform for investigating the underlying mechanisms of cisplatin resistance in a clinically relevant context, contributing to the development of targeted therapies tailored to combat resistance in stem-like ovarian cancer.

Abstract 6910: CancerModels.org: An open global cancer research platform for patient-derived cancer models

Abstract CancerModels.Org (www.cancermodels.org) is a research platform that standardises, harmonizes and integrates the complex and diverse data associated with Patient-Derived Cancer Models (PDCMs) for the cancer community. The portal publishes over 7500 models - covering patient-derived xenografts (PDX), organoids and cell lines - across 13 cancer types, including rare pediatric PDX models and models from minority ethnic backgrounds. A total of over 90 million data points are made available across a variety of data types, such as clinical metadata, molecular data and treatment-based information, which makes CancerModels.Org the largest free-to-consumer and open-access resource of this kind. Over the course of the last twelve months, the platform has been enhanced with new functionality and an updated user interface to cater for a more varied set of use cases. Users can now search for models of interest by exploring molecular data summaries for models of specific cancer types, as well as by using the intuitive search and faceted filtering options of the web interface. The data is also accessible via REST API, hence enabling offline analyses. The underpinning data model was augmented with additional dimensions and covers gene expression, gene mutation, copy number alteration, biomarkers, patient treatment and drug dosing studies. For an improved prioritization of PDCMs we performed knowledge enrichment by linking to external resources, such as publication platforms, cancer-specific annotation tools (COSMIC, CIViC, OncoMX, OpenCRAVAT, ClinGen), and raw data archives (ENA, EGA, GEO, dbGAP). More recently, we added immune-related features of tumors (HLA, MSI, TMB) and image data (also accessible via EMBL-EBI’s BioImage archive). Finally, to streamline model and data submission, we made available a Metadata dictionary and a Metadata validation service. Future work will focus on the curation of rare models with rich accessible metadata and data, new data visualizations, integration of new data types and resources, as well as devising a model quality rating using user feedback. These developments will maximize utility and improve reusability of models and data, and reduce barriers to model and data sharing. CancerModels.Org is deeply integrated into the general patient-derived cancer models landscape, underpinning or contributing to the data and/or software infrastructure of some of the long-running consortia, such as EUROPDX and PDXNet. The resource is freely available under an Apache 2.0 license (https://github.com/PDCMFinder). Citation Format: Zinaida Perova, Mauricio Martinez, Tushar Mandloi, Marcelo Rios Almanza, Steven Neuhauser, Dale Degley, Debra Krupke, Carol Bult, Helen Parkinson. CancerModels.org: An open global cancer research platform for patient-derived cancer models [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 6910.

Abstract 6429: Critical role of elevated TMEM176B gene expression in humanized patient-derived xenografts mouse models of triple negative breast cancer

Abstract Objective: In the cancer research, a highly promising in vivo platform for personalized treatment involves the adoption of an advanced approach—specifically, the grafting of patient-derived xenografts (PDX) onto humanized mouse models. These models capture distinctive aspects of interaction with the human immune system and the tumor microenvironment (TME). In this study, we have engineered humanized triple-negative breast cancer (TNBC) PDX models to observe alterations in differentially expressed genes, thereby enhancing our understanding of the intricacies of personalized treatment in this context. Method: We utilized two TNBC PDX models established for the humanized models, where CD34+ hematopoietic stem cells were transplanted into immunodeficient mice. RNA sequencing was performed to identify altered gene expression in humanized PDX models compared to NSG PDXs. Additionally, we generated stable cell lines overexpressing TMEM176B in MDAMB231 and Hs578T cells, and we knocked down TMEM176B in 4T1 cells using recombinant techniques Results: In the humanized model, the growth of PDX tumors did not show a significantly faster or markedly different rate compared to previous studies. However, upon conducting RNA sequencing in the PDX model, the expression of the TMEM176B gene was consistently downregulated. Consequently, we transfected and observed that the increased expression of TMEM176B in MDAMB231 and Hs578T cell lines resulted in enhanced cell proliferation in vitro. Transplanting MDAMB231 cells overexpressing TMEM176B into athymic nude mice resulted in accelerated tumor growth. The study further investigates the expression of TMEM176B in an immune-competent environment by knocking down the gene in 4T1 cells or transplanting the control group into a balb/c mouse model. Tumors with TMEM176B knockdown exhibited inhibited growth, increased CD3+ T cell infiltration, and significant inhibition when treated with anti-PD-L1 compared to the control group. Conclusion: This research demonstrates the utility of PDX models, particularly humanized PDX models, in studying the complexities of cancer biology and the tumor microenvironment. The findings regarding TMEM176B and its role in tumorigenesis and immune responses in triple-negative breast cancer provide valuable insights for further research and potential therapeutic interventions. Citation Format: Yujeong Her, Jihui Yun, Woohang Heo, Jong-Il Kim, Han-Byoel Lee, Wonshik Han, Hyeong-Gon Moon. Critical role of elevated TMEM176B gene expression in humanized patient-derived xenografts mouse models 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 6429.

Abstract 5911: In vivo efficacy of a novel peptide-conjugated drug in patient-derived xenograft models of breast cancer

Abstract Introduction: Antibody and peptide-conjugated drugs are rapidly entering the clinic for the treatment of patients with early and advanced breast cancer. These drugs are designed to achieve more targeted delivery of cytotoxic agents to tumor cells with robust clinical activity. ARB-1-6, a sortilin (SORT1) targeted peptide conjugated to the cytotoxic agent MMAE, has demonstrated pre-clinical activity and tolerability in cell line xenografts of breast cancer. To further characterize its spectrum of antitumor activity and biomarker correlates we evaluated ARB-1-6 in a collection of clinically and genomically annotated breast cancer patient-derived xenografts (PDX). Methods: Breast cancer PDX models were generated and propagated under IRB approved protocols [14-8358]. ARB-1-6 was dosed in tumor-bearing SCID mice by tail vein injection at 3 mg/kg weekly x 4 doses. Tumor volume was measured twice weekly until day 35 or until models reached humane endpoints, after which tumors were collected. Animals were weighed regularly and assessed for treatment-related toxicity. Results: 7 models (5 TN and 2 HR) have completed efficacy assessment to date. 3/7 models were derived from treatment naïve patients while 4/7 were derived from pre-treated patients (Table 1). Complete response (mRECIST) was seen in 5/7 (71.4%) models with stable disease occurring in 2/7 (28.6%). ARB-1-6 was well tolerated with no weight loss observed. Complete tumor regression was seen in a PDX derived from a patient with clinical resistance to a TROP2 antibody drug conjugate (ADC). Antitumor activity was observed in models with low SORT1 RNA expression; SORT1 IHC and other correlatives studies are underway. Conclusion: ARB-1-6 demonstrates substantial preclinical activity in PDX models at doses that are well tolerated in mice. Treatment of additional models is ongoing. Full results and correlative analyses including relationships between antitumor activity and target protein expression will be presented. PDX Model Characteristics and Patient Treatment PDX Subtype Pt. Treatment 1 TN AC-T 2 TN FEC-D, Gem+Carbo 3 TN AC-T 4 TN No 5 TN No 6 HR No 7 HR TC, ET, Cape, Gem+Cis, TROP2-ADC Citation Format: Mitchell J. Elliott, Meghan Mcguire, Jennifer Silvester, Chantal Tobin, Samah El Ghamrasni, Francine Lui, Andrew Zhai, Ozge Yoluk, Aron Broom, Tracy Stone, Glenn Butterfoss, Serban Popa, Tianyu Lu, Chris Ing, David White, David W. Cescon. In vivo efficacy of a novel peptide-conjugated drug in patient-derived xenograft models of 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 5911.