Patient-derived Cancer Organoids Research Articles

Discordant Health Implications and Molecular Mechanisms of Vitamin D in Clinical and Preclinical Studies of Prostate Cancer: A Critical Appraisal of the Literature Data.

Clinical and preclinical studies have provided conflicting data on the postulated beneficial effects of vitamin D in patients with prostate cancer. In this opinion piece, we discuss reasons for discrepancies between preclinical and clinical vitamin D studies. Different criteria have been used as evidence for the key roles of vitamin D. Clinical studies report integrative cancer outcome criteria such as incidence and mortality in relation to vitamin D status over time. In contrast, preclinical vitamin D studies report molecular and cellular changes resulting from treatment with the biologically active vitamin D metabolite, 1,25-dihydroxyvitamin D3 (calcitriol) in tissues. However, these reported changes in preclinical in vitro studies are often the result of treatment with biologically irrelevant high calcitriol concentrations. In typical experiments, the used calcitriol concentrations exceed the calcitriol concentrations in normal and malignant prostate tissue by 100 to 1000 times. This raises reasonable concerns regarding the postulated biological effects and mechanisms of these preclinical vitamin D approaches in relation to clinical relevance. This is not restricted to prostate cancer, as detailed data regarding the tissue-specific concentrations of vitamin D metabolites are currently lacking. The application of unnaturally high concentrations of calcitriol in preclinical studies appears to be a major reason why the results of preclinical in vitro studies hardly match up with outcomes of vitamin D-related clinical studies. Regarding future studies addressing these concerns, we suggest establishing reference ranges of tissue-specific vitamin D metabolites within various cancer entities, carrying out model studies on human cancer cells and patient-derived organoids with biologically relevant calcitriol concentrations, and lastly improving the design of vitamin D clinical trials where results from preclinical studies guide the protocols and endpoints within these trials.

Abstract RF01-05: Functional assessment of RAD51 foci and replication fork dynamics in PARPi resistant BRCA1/2 mutated breast cancer

Abstract Background: Although platinum salts (Pt) or Poly (ADP-Ribose) Polymerase inhibitors (PARPi) are effective in treating homologous recombination defective (HRD) breast cancer, resistance often emerges, especially in advanced disease. Predicting response and relapse is complex, even in patients with germline BRCA1/2 mutations (gBRCA1/2m). Clinically approved HRD detection methods are limited to identification of pathogenic mutations in HR genes or mutational signatures in the genome of tumors caused by HRD. In PDX models derived from HRD breast cancer, the restoration of nuclear RAD51 foci formation, a key feature of functional HR, can predict resistance to HRD-targeted treatment.1 In addition, the restoration of replication fork stability, despite PARPi or induction of Pt adducts that induce replication fork arrest and collapse, confers resistance in pre-clinical models2; to date this resistance mechanism has not been clinically validated. Here we analyse RAD51 foci in FFPE samples and DNA replication fork dynamics, using DNA fibre combing assays, in patient derived organoids (PDO) relating these to clinical response to illustrate how such assays might predict clinical HRD-targeted therapy resistance in metastatic breast cancer (MBC). Patients and Methods: We used immunofluorescent detection of RAD51 foci as a marker for HR proficiency (HRP) in tumors from 29 patients with gBRCA1/2m with MBC treated with HRD-targeted treatment (n=6 PARPi, n=2 Pt and n=21 both agents in sequence). All patients developed resistance that was either de novo or acquired. RAD51 and BRCA1 foci were scored in a minimum of 50 geminin (a marker of S/G2 phase) positive tumor cells; cells with ≥5 foci were classified as positive, and tumours where ≤10% or >10% of cells were positive were considered HRD or HRP, respectively. DNA replication fork dynamics were assessed in with or without PARPi using thymidine analogue labelling. DNA fibre analysis was performed in PDOs developed from fresh tumor sampling of HRD-targeted treatment sensitive or resistant tumors, to determine the relationship between replication fork dynamics, stability and PARPi sensitivity. Results: RAD51 analysis was performed on 9 treatment naïve samples (n=9 patients), 8 samples obtained after HRD-targeted treatment resistance (n=8 patients) and 27 samples obtained pre and post HRD-targeted treatment resistance (n=12 patients). Functional HRD by RAD51 in treatment naive samples was seen in 100% (n=17) of patients with acquired resistance and 66% of patients with de novo resistance. All patients, whether with de novo or acquired resistance, exhibited high RAD51 scores in post-resistance tumour samples, suggesting restoration of HR function is the dominant mechanism of PARPi resistance. As such, RAD51 analysis shows potential as a biomarker of clinical PARPi resistance. Replication fork stability fibre was analysed after exposure to potent PARP1 trapping inhibitors or an ATRi control in 3 PDOs (2 gBRCA1m, 1 BRCAwt). As controls we used an isogenic 2D cell line with and without a CRISPR engineered BRCA1 reversion mutation (SUM149 parental BRCA1m and SUM149BS*1 revertant) or with a PARP1 mutation (SUM149 TR2 clone) that prevents PARP1 being trapped on DNA. These experiments indicate that replication fork dynamics can be assessed in “patient derived” models of breast cancer and that PARPi sensitivity was associated with PARPi induced replication fork instability (median ratio IdU:CldU in resistant lines: 0.98, sensitive lines: 0.60). Conclusion: We show that HRP restoration and RAD51 foci in advanced BRCA1/2m breast cancers is the dominant form resistance to HRD-targeted treatment. We also demonstrate for the first time that analysis of DNA replication fork dynamics can be carried out in breast cancer PDOs and could be further explored as a functional predictive biomarker of PARPi resistance. 1.Pellegrino et al, 2022 (PMID: 35425960) 2.Chaudhuri et al, 2016 (PMID: 27443740) Citation Format: Elizabeth Harvey-Jones, Maya Raghunandan, Luisa Robbez-Masson, Thanussuyah Alaguthurai, Alba Llop-Guevara, Jennifer Trendell, Olga Rodriguez, Marta Guzman, Daniel Weekes, Christelle deRenty, Eleanor Knight, Rebecca Marlow, Christopher Starling, Ruifang Liu, Nivedita Ravindran, Ioannis Roxanis, Natalia Lukashchuk, Violeta Serra, Stephen Pettitt, Christopher Lord, Andrew NJ Tutt. Functional assessment of RAD51 foci and replication fork dynamics in PARPi resistant BRCA1/2 mutated breast cancer [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 RF01-05.

Abstract PO1-06-01: Clinical Efficacy of Tumor Organoid-Guided Cancer Therapy for Locally Advanced Unresectable or Metastatic Breast Cancer

Abstract Purpose: Patient-derived organoids (PDOs) may facilitate treatment selection, but the feasibility of using breast cancer PDOs to guide personalized treatment in clinical practice has not been fully investigated. This study aimed to assess the clinical efficacy of treatment guided by PDO drug sensitivity tests (OGT) versus treatment of physician’s choice (TPC) in patients with locally advanced unresectable or metastatic breast cancer (MBC) and to explore the potential of PDOs to reveal mechanisms underlying treatment resistance. Methods: Patients diagnosed with MBC were recruited between January 2020 and August 2022. PDOs were established from biopsies specimens or malignant effusion samples. The efficacy of customized drug panels was determined by measuring cell mortality after drug exposure. Patients receiving OGT were matched 1:2 by nearest neighbor propensity scores with patients receiving TPC. The primary clinical outcome was progression-free survival. Secondary outcomes included objective response rate and disease control rate. Targeted gene sequencing and pathway enrichment analysis were performed. Results: 46 PDOs (46 of 51, 90.2%) were generated from 45 MBC patients. PDO drug screening showed an accuracy of 81.1% (95% CI 67.6%-91.9%) in predicting patients' clinical responses. 36 OGT patients were matched to 69 TPC patients. OGT was associated with prolonged median progression-free survival (11.0 months vs 5.0 months; unadjusted hazard ratio 0.53 [95% CI 0.33-0.85]; P=0.01) and improved disease control (88.9% vs 63.8%; unadjusted odd ratio 4.26 [1.44-18.62]) compared with TPC. The objective response rate of both groups was similar. Pathway enrichment analysis uncovered differentially modulated pathways implicated in DNA repair and transcriptional regulation in patients less sensitive to capecitabine/gemcitabine, and pathways associated with cell cycle regulation in patients less sensitive to palbociclib. Conclusions: MBC patients treated with OGT were associated with superior progression-free survival and disease control compared with TPC. PDO-based functional precision medicine is a feasible strategy for treatment optimization and customization in MBC and may enhance our understanding of therapeutic resistance. Citation Format: Ying-Yi Lin, Hong-Fei Gao, Hong Li, Bo-Lei Du, Min-Yi Cheng, Jia-Chen Zou, Xing-xing Zheng, Teng Zhu, Ting-Ting Li, Sheng Li, Kun Wang. Clinical Efficacy of Tumor Organoid-Guided Cancer Therapy for Locally Advanced Unresectable or Metastatic Breast Cancer [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 PO1-06-01.

Methylation of the chromatin modifier KMT2D by SMYD2 contributes to therapeutic response in hormone-dependent breast cancer

Activating mutations in PIK3CA are frequently found in estrogen-receptor-positive (ER+) breast cancer, and the combination of the phosphatidylinositol 3-kinase (PI3K) inhibitor alpelisib with anti-ER inhibitors is approved for therapy. We have previously demonstrated that the PI3K pathway regulates ER activity through phosphorylation of the chromatin modifier KMT2D. Here, we discovered a methylation site on KMT2D, at K1330 directly adjacent to S1331, catalyzed by the lysine methyltransferase SMYD2. SMYD2 loss attenuates alpelisib-induced KMT2D chromatin binding and alpelisib-mediated changes in gene expression, including ER-dependent transcription. Knockdown or pharmacological inhibition of SMYD2 sensitizes breast cancer cells, patient-derived organoids, and tumors to PI3K/AKT inhibition and endocrine therapy in part through KMT2D K1330 methylation. Together, our findings uncover a regulatory crosstalk between post-translational modifications that fine-tunes KMT2D function at the chromatin. This provides a rationale for the use of SMYD2 inhibitors in combination with PI3Kα/AKT inhibitors in the treatment of ER+/PIK3CA mutant breast cancer.

The combination of breast cancer PDO and mini-PDX platform for drug screening and individualized treatment.

The majority of advanced breast cancers exhibit strong aggressiveness, heterogeneity, and drug resistance, and currently, the lack of effective treatment strategies is one of the main challenges that cancer research must face. Therefore, developing a feasible preclinical model to explore tailored treatments for refractory breast cancer is urgently needed. We established organoid biobanks from 17 patients with breast cancer and characterized them by immunohistochemistry (IHC) and next generation sequencing (NGS). In addition, we in the first combination of patient-derived organoids (PDOs) with mini-patient-derived xenografts (Mini-PDXs) for the rapid and precise screening of drug sensitivity. We confirmed that breast cancer organoids are a high-fidelity three-dimension (3D) model invitro that recapitulates the original tumour's histological and genetic features. In addition, for a heavily pretreated patient with advanced drug-resistant breast cancer, we combined PDO and Mini-PDX models to identify potentially effective combinations of therapeutic agents for this patient who were alpelisib + fulvestrant. In the drug sensitivity experiment of organoids, we observed changes in the PI3K/AKT/mTOR signalling axis and oestrogen receptor (ER) protein expression levels, which further verified the reliability of the screening results. Our study demonstrates that the PDO combined with mini-PDX model offers a rapid and precise drug screening platform that holds promise for personalized medicine, improving patient outcomes and addressing the urgent need for effective therapies in advanced breast cancer.

Quantifying Y chromosome loss in primary and metastatic prostate cancer by chromosome painting.

Somatic Y chromosome loss in hematopoietic cells is associated with higher mortality in men. However, the status of the Y chromosome in cancer tissue is not fully known due to technical limitations, such as difficulties in labelling and sequencing DNA from the Y chromosome. We have developed a system to quantify Y chromosome gain or loss in patient-derived prostate cancer organoids. Using our system, we observed Y chromosome loss in 4 of the 13 (31%) patient-derived metastatic castration-resistant prostate cancer (mCRPC) organoids; interestingly, loss of Yq (long arm of the Y chromosome) was seen in 38% of patient-derived organoids. Additionally, potential associations were observed between mCRPC and Y chromosome nullisomy. The prevalence of Y chromosome loss was similar in primary and metastatic tissue, suggesting that Y chromosome loss is an early event in prostate cancer evolution and may not a result of drug resistance or organoid derivation. This study reports quantification of Y chromosome loss and gain in primary and metastatic prostate cancer tissue and lays the groundwork for further studies investigating the clinical relevance of Y chromosome loss or gain in mCRPC.

Genome-wide CRISPR screens identify the YAP/TEAD axis as a driver of persister cells in EGFR mutant lung cancer

Most lung cancer patients with metastatic cancer eventually relapse with drug-resistant disease following treatment and EGFR mutant lung cancer is no exception. Genome-wide CRISPR screens, to either knock out or overexpress all protein-coding genes in cancer cell lines, revealed the landscape of pathways that cause resistance to the EGFR inhibitors osimertinib or gefitinib in EGFR mutant lung cancer. Among the most recurrent resistance genes were those that regulate the Hippo pathway. Following osimertinib treatment a subpopulation of cancer cells are able to survive and over time develop stable resistance. These ‘persister’ cells can exploit non-genetic (transcriptional) programs that enable cancer cells to survive drug treatment. Using genetic and pharmacologic tools we identified Hippo signalling as an important non-genetic mechanism of cell survival following osimertinib treatment. Further, we show that combinatorial targeting of the Hippo pathway and EGFR is highly effective in EGFR mutant lung cancer cells and patient-derived organoids, suggesting a new therapeutic strategy for EGFR mutant lung cancer patients.

The estrogen signaling pathway reprograms prostate cancer cell metabolism and supports proliferation and disease progression.

Just like the androgen receptor (AR), the estrogen receptor α (ERα) is expressed in the prostate and is thought to influence prostate cancer (PCa) biology. Yet the incomplete understanding of ERα functions in PCa hinders our ability to fully comprehend its clinical relevance and restricts the repurposing of estrogen-targeted therapies for the treatment of this disease. Using 2 human PCa tissue microarray cohorts, we first demonstrate that nuclear ERα expression was heterogeneous among patients, being detected in only half of the tumors. Positive nuclear ERα levels were correlated with disease recurrence, progression to metastatic PCa, and patient survival. Using in vitro and in vivo models of the normal prostate and PCa, bulk and single-cell RNA-Seq analyses revealed that estrogens partially mimicked the androgen transcriptional response and activated specific biological pathways linked to proliferation and metabolism. Bioenergetic flux assays and metabolomics confirmed the regulation of cancer metabolism by estrogens, supporting proliferation. Using cancer cell lines and patient-derived organoids, selective estrogen receptor modulators, a pure anti-estrogen, and genetic approaches impaired cancer cell proliferation and growth in an ERα-dependent manner. Overall, our study revealed that, when expressed, ERα functionally reprogrammed PCa metabolism, was associated with disease progression, and could be targeted for therapeutic purposes.

Abstract P43: Optimization of DNA Methyltransferase Inhibitors-based Combination to Target the Epigenome of Gastric Cancer

Abstract Aberrant DNA methylation is one of the critical epigenetic modifications that has become a widespread phenotype in solid tumours. Similar to haematological malignancies, many studies have shown that the DNA methylation landscape of solid tumours exhibits a pattern of either hypermethylation of the promoter regions of tumour-suppressive genes in advanced cancer or global hypomethylation in the early stages of carcinogenesis. Additionally, dysregulated DNA methylation also seems to remodel the tumour microenvironment and affect immune cells' response towards immune checkpoint inhibitors. In gastric cancer, comprehensive DNA methylation analyses have demonstrated that gastric tumours carry the CpG island methylation phenotype (CIMP), resulting in extended molecular-based subgroups such as the extremely high-methylation epigenotype (E-HME), HME, and low-methylation epigenotype (LME). Therefore, conventional histology grading and molecular subtyping are insufficient to address the multifaceted epigenome of gastric cancer. As such, current standard-of-care (SOC) therapy is not able to overcome cancer relapse and tumour metastasis. Clearly, this shows the therapeutic potential of using DNA hypomethylating drugs like DNA methyltransferase inhibitors (DNMTi) for solid tumours such as gastric cancer. In our study, we exploited the engineering-based Quadratic Phenotypic Optimization Platform (QPOP) to identify top-ranking DNMTi-based drug combinations across gastric cancer cell lines (GC-CL) and patient-derived organoids (GC-PDO). Based on QPOP analysis, we showed that a non-SOC drug combination, Docetaxel/5-Azacytidine is a frequently top-ranking. Besides, our present findings suggest that CIMP-high gastric cancer cells are more susceptible towards DNMT inhibitors through the specific reduction of DNMT1 levels. As we surveyed the effects of Docetaxel/5-Azacytidine in a CIMP-high GC-CL via Infinium methylation array, we observed robust gene methylation changes that are involved in non-canonical Wnt Signaling and EMT. On the other hand, proteomic analysis revealed a small subset of our panel of GC lines that are positive for the cancer-testis antigen, MageA4. Interestingly, the protein expression of MageA4 in some CIMP-high lines is restored upon treatment with DNMT inhibitors. This evinces that DNMTi can subject epigenetically silenced MageA4 gastric tumours to autologous T-cell receptor therapy. Taken altogether, we plan to further interrogate the mechanisms of DNMT inhibitors in sensitizing CIMP-high gastric tumours towards Taxanes by acting on the non-canonical Wnt pathway and EMT activators. Citation Format: Lissa Hooi, Vivien Koh, Dexter Kai Hao Thng, Jasmine Goh, Lim Jhin Jieh, Lee Rui Xue, Masturah Bte Mohd Abdul Rashid, Toh Tan Boon, Wei Peng Yong, Edward Kai-Hua Chow. Optimization of DNA Methyltransferase Inhibitors-based Combination to Target the Epigenome of Gastric Cancer [abstract]. In: Proceedings of Frontiers in Cancer Science; 2023 Nov 6-8; Singapore. Philadelphia (PA): AACR; Cancer Res 2024;84(8_Suppl):Abstract nr P43.

Abstract P37: Establishment of Gastric Organoids Biobank and Its Usage

Abstract Gastric cancer is highly heterogeneous. To analyze their biology, patient-derived organoids (PDOs) are useful because they maintain intra-tumor heterogeneity (ITH) as well as inter-patient heterogeneity. Recently, four groups reported the establishment of gastric PDOs. However, it is still not easy because of the need to overcome a common problem: “contamination” of the culture with “non-cancer cell”-derived organoids from the specimen. These non-cancer organoids often overgrow and became dominant. Furthermore, PDOs have another limitation. They contain only epithelial cells and no other types of cells, making it difficult to study the tumor microenvironment (TME). Since October 2021, we have been working on establishing our own gastric PDO biobank. 63 gastric PDOs have been successfully established from 24 patients. Cancer organoids are enriched by manual selection under a microscopy. Our biobank contains 35 gastric cancer PDOs, 16 of which were confirmed as cancer using WES and WTS. Profiling for the remaining PDOs is ongoing. 12 fibroblasts and 26 cancer associated fibroblasts (CAFs) have also been successfully established. To overcome the difficulties of TME research with PDOs, co-culture platform for PDOs and fibroblasts has been established. This co-culture platform can provide new insights into the functions of CAFs, one of the major components of TME. In this poster, I will describe the progress of our gastric PDO biobank establishment and the prospects for my projects using it. Citation Format: Takeshi Hagihara, Kie Kyon Huang, Raghav Sundar, Tomoyuki Uchihara, Clara Shi Ya Ng, Su Ting Tay, Angie Lay Keng Tan, Jimmy Bok Yan So, Patrick Tan. Establishment of Gastric Organoids Biobank and Its Usage [abstract]. In: Proceedings of Frontiers in Cancer Science; 2023 Nov 6-8; Singapore. Philadelphia (PA): AACR; Cancer Res 2024;84(8_Suppl):Abstract nr P37.

Neratinib could be effective as monotherapy or in combination with trastuzumab in HER2-low breast cancer cells and organoid models

BackgroundPrevious studies have suggested that patients with HER2-low breast cancers do not benefit from trastuzumab treatment although the reasons remain unclear.MethodsWe investigated the effect of trastuzumab monotherapy and its combination with different HER2 targeting treatments in a panel of breast cancer cell lines and patient-derived organoids (PDOs) using biochemical methods and cell viability assays.ResultsCompared to sensitive HER2 over-expressing (IHC3 + ) breast cancer cells, increasing doses of trastuzumab could not achieve IC50 in MDA-MB-361 (IHC 2 + FISH + ) and MDA-MB-453 (IHC 2 + FISH-) cells which showed an intermediate response to trastuzumab. Trastuzumab treatment induced upregulation of HER ligand release, resulting in the activation of HER receptors in these cells, which could account for their trastuzumab insensitivity. Adding a dual ADAM10/17 inhibitor to inhibit the shedding of HER ligands in combination with trastuzumab only showed a modest decrease in the cell viability of HER2-low breast cancer cells and PDOs. However, the panHER inhibitor neratinib was an effective monotherapy in HER2-low breast cancer cells and PDOs, and showed additive effects when combined with trastuzumab.ConclusionThis study demonstrates that neratinib in combination with trastuzumab may be effective in a subset of HER2-low breast cancers although further validation is required in a larger panel of PDOs and in future clinical studies.

Combination of bazedoxifene with chemotherapy and SMAC-mimetics for the treatment of colorectal cancer

Excessive STAT3 signalling via gp130, the shared receptor subunit for IL-6 and IL-11, contributes to disease progression and poor survival outcomes in patients with colorectal cancer. Here, we provide evidence that bazedoxifene inhibits tumour growth via direct interaction with the gp130 receptor to suppress IL-6 and IL-11-mediated STAT3 signalling. Additionally, bazedoxifene combined with chemotherapy synergistically reduced cell proliferation and induced apoptosis in patient-derived colon cancer organoids. We elucidated that the primary mechanism of anti-tumour activity conferred by bazedoxifene treatment occurs via pro-apoptotic responses in tumour cells. Co-treatment with bazedoxifene and the SMAC-mimetics, LCL161 or Birinapant, that target the IAP family of proteins, demonstrated increased apoptosis and reduced proliferation in colorectal cancer cells. Our findings provide evidence that bazedoxifene treatment could be combined with SMAC-mimetics and chemotherapy to enhance tumour cell apoptosis in colorectal cancer, where gp130 receptor signalling promotes tumour growth and progression.

Examination of Wnt signaling as a therapeutic target for pancreatic ductal adenocarcinoma (PDAC) using a pancreatic tumor organoid library (PTOL).

Pancreatic ductal adenocarcinoma (PDAC) presents at advanced stages and is refractory to most treatment modalities. Wnt signaling activation plays a critical role in proliferation and chemotherapeutic resistance. Minimal media conditions, growth factor dependency, and Wnt dependency were determined via Wnt inhibition for seven patient derived organoids (PDOs) derived from pancreatic tumor organoid libraries (PTOL). Organoids demonstrating response in vitro were assessed in vivo using patient-derived xenografts. Wnt (in)dependent gene signatures were identified for each organoid. Panc269 demonstrated a trend of reduced organoid growth when treated with ETC-159 in combination with paclitaxel or gemcitabine as compared with chemotherapy or ETC-159 alone. Panc320 demonstrated a more pronounced anti-proliferative effect in the combination of ETC-159 and paclitaxel but not with gemcitabine. Panc269 and Panc320 were implanted into nude mice and treated with ETC-159, paclitaxel, and gemcitabine as single agents and in combination. The combination of ETC-159 and paclitaxel demonstrated an anti-tumor effect greater than ETC-159 alone. Extent of combinatory treatment effect were observed to a lesser extent in the Panc320 xenograft. Wnt (in)dependent gene signatures of Panc269 and 320 were consistent with the phenotypes displayed. Gene expression of several key Wnt genes assessed via RT-PCR demonstrated notable fold change following treatment in vivo. Each pancreatic organoid demonstrated varied niche factor dependencies, providing an avenue for targeted therapy, supported through growth analysis following combinatory treatment of Wnt inhibitor and standard chemotherapy in vitro. The clinical utilization of this combinatory treatment modality in pancreatic cancer PDOs has thus far been supported in our patient-derived xenograft models treated with Wnt inhibitor plus paclitaxel or gemcitabine. Gene expression analysis suggests there are key Wnt genes that contribute to the Wnt (in)dependent phenotypes of pancreatic tumors, providing plausible mechanistic explanation for Wnt (in)dependency and susceptibility or resistance to treatment on the genotypic level.

A phenotypic screening approach to target p60AmotL2-expressing invasive cancer cells

BackgroundTumor cells have the ability to invade and form small clusters that protrude into adjacent tissues, a phenomenon that is frequently observed at the periphery of a tumor as it expands into healthy tissues. The presence of these clusters is linked to poor prognosis and has proven challenging to treat using conventional therapies. We previously reported that p60AmotL2 expression is localized to invasive colon and breast cancer cells. In vitro, p60AmotL2 promotes epithelial cell invasion by negatively impacting E-cadherin/AmotL2-related mechanotransduction.MethodsUsing epithelial cells transfected with inducible p60AmotL2, we employed a phenotypic drug screening approach to find compounds that specifically target invasive cells. The phenotypic screen was performed by treating cells for 72 h with a library of compounds with known antitumor activities in a dose-dependent manner. After assessing cell viability using CellTiter-Glo, drug sensitivity scores for each compound were calculated. Candidate hit compounds with a higher drug sensitivity score for p60AmotL2-expressing cells were then validated on lung and colon cell models, both in 2D and in 3D, and on colon cancer patient-derived organoids. Nascent RNA sequencing was performed after BET inhibition to analyse BET-dependent pathways in p60AmotL2-expressing cells.ResultsWe identified 60 compounds that selectively targeted p60AmotL2-expressing cells. Intriguingly, these compounds were classified into two major categories: Epidermal Growth Factor Receptor (EGFR) inhibitors and Bromodomain and Extra-Terminal motif (BET) inhibitors. The latter consistently demonstrated antitumor activity in human cancer cell models, as well as in organoids derived from colon cancer patients. BET inhibition led to a shift towards the upregulation of pro-apoptotic pathways specifically in p60AmotL2-expressing cells.ConclusionsBET inhibitors specifically target p60AmotL2-expressing invasive cancer cells, likely by exploiting differences in chromatin accessibility, leading to cell death. Additionally, our findings support the use of this phenotypic strategy to discover novel compounds that can exploit vulnerabilities and specifically target invasive cancer cells.

Abstract LB216: Static and microfluidic platforms for novel therapeutic testing in high-grade serous ovarian cancer

Abstract Background: High-Grade Serous Ovarian Cancer (HGSOC) is the most lethal OC type because of its silent progression and lack of specific markers for early detection. In this context, the timely initiation of effective treatment is imperative to prevent disease progression extending life expectancy. However, responses to treatment can vary significantly among individuals, presenting clinical challenges in selecting effective treatments, necessitating the interpretation of molecular and genomic data of the patient on a case-by-case basis. The aim of this study is to establish a highly sensitive platform, implemented with microfluidic technology, to predict patient drug responses with the goal of assisting oncologists in shaping effective treatments. Moreover, validating this platform through a retrospective study, enabling the development of innovative drugs. Methods: In this work, patient-derived ovarian cancer organoids (PDOs) were engineered for drug screening and twenty FDA approved drugs were assessed on seven PDOs derived from both primary tumors and ascites. The fidelity of PDOs in reproducing the histopathology of the primary tumour was confirmed by immunohistochemistry. Proteomics and repeated screening on high- and low-passage PDOs confirmed the reliability of the platform over time. Furthermore, to bridge the gap between static systems and the dynamic of human tumours, a microfluidic platform was employed and using fluorescence microscopy the patients' drug sensitivity was predicted (PMID: 37143603). Results: PDOs were able to replicate patients' response to the drug in a retrospective study and surprisingly, in some cases, to predict resistance to certain drugs administered on the basis of strong, clinically validated predictive biomarkers, which proved ineffective in the clinic. The platform could predict innovative therapeutic strategies as demonstrated by inhibiting the activity of Peptidylprolyl Cis/Trans Isomerase, NIMA-Interacting 1 (Pin1), a novel druggable target for OC (PMID: 22322860, 29746956, 30697729). The Pin1 inhibitor (VS10) is effective in a subset of patients resistant to platinum-based chemotherapy and synergize with doxorubicin. Finally, a microfluidic platform fluorescence based, which improved drug penetration in PDOs was developed for efficient and faster drug screening. Conclusions: This study underscores the significance of utilizing engineered PDOs to develop predictive and easy to use platforms that can truly aid oncologists in devising patient-specific treatments while circumventing the use of drugs that, despite strong recommendations, may prove ineffective. Furthermore, these platforms have demonstrated their effectiveness in the development of innovative therapeutics, such as Pin1 inhibitors, which have been proven both effective and safe in animal models, underscoring the need for clinical studies. Acknowledgments: AIRC IG23566 Citation Format: Enrico Cavarzerani, Gloria Saorin, Matteo Mauceri, Isabella Caligiuri, Michele Bartoletti, Vincenzo Canzonieri, Flavio Rizzolio. Static and microfluidic platforms for novel therapeutic testing in high-grade serous ovarian cancer [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 LB216.

Sialyl-Tn serves as a potential therapeutic target for ovarian cancer

BackgroundOvarian cancer remains the deadliest of the gynecologic cancers in the United States. There have been limited advances in treatment strategies that have seen marked increases in overall survival. Thus, it is essential to continue developing and validating new treatment strategies and markers to identify patients who would benefit from the new strategy. In this report, we sought to further validate applications for a novel humanized anti-Sialyl Tn antibody-drug conjugate (anti-STn-ADC) in ovarian cancer.MethodsWe aimed to further test a humanized anti-STn-ADC in sialyl-Tn (STn) positive and negative ovarian cancer cell line, patient-derived organoid (PDO), and patient-derived xenograft (PDX) models. Furthermore, we sought to determine whether serum STn levels would reflect STn positivity in the tumor samples enabling us to identify patients that an anti-STn-ADC strategy would best serve. We developed a custom ELISA with high specificity and sensitivity, that was used to assess whether circulating STn levels would correlate with stage, progression-free survival, overall survival, and its value in augmenting CA-125 as a diagnostic. Lastly, we assessed whether the serum levels reflected what was observed via immunohistochemical analysis in a subset of tumor samples.ResultsOur in vitro experiments further define the specificity of the anti-STn-ADC. The ovarian cancer PDO, and PDX models provide additional support for an anti-STn-ADC-based strategy for targeting ovarian cancer. The custom serum ELISA was informative in potential triaging of patients with elevated levels of STn. However, it was not sensitive enough to add value to existing CA-125 levels for a diagnostic. While the ELISA identified non-serous ovarian tumors with low CA-125 levels, the sample numbers were too small to provide any confidence the STn ELISA would meaningfully add to CA-125 for diagnosis.ConclusionsOur preclinical data support the concept that an anti-STn-ADC may be a viable option for treating patients with elevated STn levels. Moreover, our STn-based ELISA could complement IHC in identifying patients with whom an anti-STn-based strategy might be more effective.

Stem cell dynamics and cellular heterogeneity across lineage subtypes of castrate-resistant prostate cancer.

To resist lineage-dependent therapies such as androgen receptor inhibition, prostate luminal epithelial adenocarcinoma cells often adopt a stem-like state resulting in lineage plasticity and phenotypic heterogeneity. Castrate-resistant prostate adenocarcinoma can transition to neuroendocrine (NE) and occasionally to amphicrine, co-expressed luminal and NE, phenotypes. We developed castrate-resistant prostate cancer (CRPC) patient-derived organoid models that preserve heterogeneity of the originating tumor, including an amphicrine model displaying a range of luminal and NE phenotypes. To gain biological insight and to identify potential treatment targets within heterogeneous tumor cell populations, we assessed the lineage hierarchy and molecular characteristics of various CRPC tumor subpopulations. Transcriptionally similar stem/progenitor (St/Pr) cells were identified for all lineage populations. Lineage tracing in amphicrine CRPC showed that heterogeneity originated from distinct subclones of infrequent St/Pr cells that produced mainly quiescent differentiated amphicrine progeny. By contrast, adenocarcinoma CRPC progeny originated from St/Pr cells and self-renewing differentiated luminal cells. Neuroendocrine prostate cancer (NEPC) was composed almost exclusively of self-renewing St/Pr cells. Amphicrine subpopulations were enriched for secretory luminal, mesenchymal, and enzalutamide treatment persistent signatures that characterize clinical progression. Finally, the amphicrine St/Pr subpopulation was specifically depleted with an AURKA inhibitor, which blocked tumor growth. These data illuminate distinct stem cell (SC) characteristics for subtype-specific CRPC in addition to demonstrating a context for targeting differentiation-competent prostate SCs.

EUS-guided biopsies versus surgical specimens for establishing patient-derived pancreatic cancer organoids: a systematic review and meta-analysis

Background and AimsPatient-Derived Tumor Organoids (PDTOs) is a promising new disease model in pancreatic cancer for use in personalized medicine, but overall success rate (SR) of establishing these cultures from endoscopic ultrasound-guided biopsies is unknown. MethodsWe searched relevant databases publications reporting SR of PDTO establishment from pancreatic cancer. The primary outcome was SR stratified on tissue acquisition method (EUS-guided biopsies, percutaneous biopsies, and surgical specimens). ResultsWe identified 24 studies including 1,053 attempts at establishing PDTOs. Overall SR was 63% (95% CI: 54%-72%). Pooled SR of PDTO establishment from EUS-guided biopsies, percutaneous biopsies, and surgical specimens were 60% (95% CI: 43-76%), 36% (95% CI: 14-61%) and 62% (95% CI: 48-75%), respectively and did not differ significantly (p = 0.1975). ConclusionThe SR of PDTO establishment from EUS-guided biopsies is comparable to surgical specimens. Both techniques are suitable for tissue acquisition for PDTOs in clinical and research settings.

A novel dihydroacridine derivative targets epidermal growth factor receptor-expressing cancer cells in vitro and in vivo.

Small molecules are considered a source of novel medicines targeting carcinogenic intracellular pathways including epidermal growth factor receptor (EGFR) signaling. The main goal of the study is to assess whether LHT-17-19 could be considered an effective target molecule against EGFR-expressing tumor cells in silico, in vitro, and in vivo. This was an in vivo, ex vivo, and in vivo experimental study. LHT-17-19 affinity to EGFR's kinase domain was assessed by the ligand's molecular docking. EGFR-expressing Hs746T human gastric cancer cell culture and patient-derived organoid (PDO) model of EGFR-positive breast cancer (BC) were used for in vitro assessment of the molecule anticancer property. IC50 and GI50 indexes were estimated using MTT- and MTS-based tests, respectively. Anticancer activity of LHT-17-19 against EGFR-expressing mutant lung carcinoma was studied on patient-derived xenograft (PDX) model established in 10 humanized BALB/c male mice. Continuous variables were presented as a mean ± standard deviation. Intergroup differences were assessed by two-way t-test. Kaplan-Meier's curves were used for survival analysis. High affinity of LHT-17-19 for the EGFR kinase domain with dG score -7.9 kcal/mol, EDoc-5.45 kcal/mol, and Ki 101.24 uM was due to intermolecular π-σ bonds formation and the ligand intramolecular transformation. LHT-17-19 induced anti-EGFR-expressing gastric cancer cells cytotoxicity with IC50 0.32 µM (95% confidence interval [CI] 0.11-0.54 µM). The derivative inhibited growth of EGFR-expressing BC PDO with GI50 16.25 µM (95% CI 4.44-28.04 µM). 2 mg/kg LHT-17-19 intravenously daily during 7 days inhibited PDX tumor growth and metastatic activity, prolonged animals' survival, and eliminated EGFR-mutant lung cancer cells from residual tumor's node. LHT-17-19 may be considered a molecular platform for further search of promising molecules, EGFR-expressing cancer cell inhibitors.

Establishment of patient-derived organoids for guiding personalized therapies in breast cancer patients.

Breast cancer has become the most commonly diagnosed cancer. The intra- and interpatient heterogeneity induced a considerable variation in treatment efficacy. There is an urgent requirement for preclinical models to anticipate the effectiveness of individualized drug responses. Patient-derived organoids (PDOs) can accurately recapitulate the architecture and biological characteristics of the origin tumor, making them a promising model that can overtake many limitations of cell lines and PDXs. However, it is still unclear whether PDOs-based drug testing can benefit breast cancer patients, particularly those with tumor recurrence or treatment resistance. Fresh tumor samples were surgically resected for organoid culture. Primary tumor samples and PDOs were subsequently subjected to H&E staining, immunohistochemical (IHC) analysis, and whole-exome sequencing (WES) to make comparisons. Drug sensitivity tests were performed to evaluate the feasibility of this model for predicting patient drug response in clinical practice. We established 75 patient-derived breast cancer organoid models. The results of H&E staining, IHC, and WES revealed that PDOs inherited the histologic and genetic characteristics of their parental tumor tissues. The PDOs successfully predicted the patient's drug response, and most cases exhibited consistency between PDOs' drug susceptibility test results and the clinical response of the matched patient. We conclude that the breast cancer organoids platform can be a potential preclinical tool used for the selection of effective drugs and guided personalized therapies for patients with advanced breast cancer.