Personalized Medicine Approaches in Prostate Cancer Employing Patient Derived 3D Organoids and Humanized Mice

Progress, implications, and challenges in using humanized immune system mice in CAR-T therapy-Application evaluation and improvement

In recent years, humanized immune system (HIS) mice have been gradually used as models for preclinical research in pharmacotherapies and cell therapies with major breakthroughs in tumor and other fields, better mimicking the human immune system and the tumor immune microenvironment, compared to traditional immunodeficient mice. To better promote the application of HIS mice in preclinical research, we selectively summarize the current prevalent and breakthrough research and evaluation of chimeric antigen receptor (CAR) -T cells in various antiviral and antitumor treatments. By exploring its application in preclinical research, we find that it can better reflect the actual clinical patient condition, with the advantages of providing high-efficiency detection indicators, even for progressive research and development. We believe that it has better clinical patient simulation and promotion for the updated design of CAR-T cell therapy than directly transplanted immunodeficient mice. The characteristics of the main models are proposed to improve the use defects of the existing models by reducing the limitation of antihost reaction, combining multiple models, and unifying sources and organoid substitution. Strategy study of relapse and toxicity after CAR-T treatment also provides more possibilities for application and development.

Single-Cell and Spatial Analysis of Emergent Organoid Platforms

Organoids have emerged as a promising advancement of the two-dimensional (2D) culture systems to improve studies in organogenesis, drug discovery, precision medicine, and regenerative medicine applications. Organoids can self-organize as three-dimensional (3D) tissues derived from stem cells and patient tissues to resemble organs. This chapter presents growth strategies, molecular screening methods, and emerging issues of the organoid platforms. Single-cell and spatial analysis resolve organoid heterogeneity to obtain information about the structural and molecular cellular states. Culture media diversity and varying lab-to-lab practices have resulted in organoid-to-organoid variability in morphology and cell compositions. An essential resource is an organoid atlas that can catalog protocols and standardize data analysis for different organoid types. Molecular profiling of individual cells in organoids and data organization of the organoid landscape will impact biomedical applications from basic science to translational use.

Establishment and characterization of prostate organoids from treatment-naïve patients with prostate cancer

Three-dimensional (3D) organoid culture systems are emerging as potential reliable tools to investigate basic developmental processes of human disease, especially cancer. The present study used established and modified culture conditions to report successful generation and characterization of patient-derived organoids from fresh primary tissue specimens of patients with treatment-naïve prostate cancer (PCa). Fresh tissue specimens were collected, digested enzymatically and the resulting cell suspensions were plated in a 3D environment using Matrigel as an extracellular matrix. Previously established 12-factor medium for organoid culturing was modified to create a minimal 5-factor medium. Organoids and corresponding tissue specimens were characterized using transcriptomic analysis, immunofluorescent analysis, and immunohistochemistry. Furthermore, patient-derived organoids were used to assess the drug response. Treatment-naïve patient-derived PCa organoids were obtained from fresh radical prostatectomy specimens. These PCa organoids mimicked the heterogeneity of corresponding parental tumor tissue. Histopathological analysis demonstrated similar tissue architecture and cellular morphology, as well as consistent immunohistochemical marker expression. Also, the results confirmed the potential of organoids as an in vitro model to assess potential personalized treatment responses as there was a differential drug response between different patient samples. In conclusion, the present study investigated patient-derived organoids from a cohort of treatment-naïve patients. Derived organoids mimicked the histological features and prostate lineage profiles of their corresponding parental tissue and may present a potential model to predict patient-specific treatment response in a pre-clinical setting.

Optimized 3D Culture of Hepatic Cells for Liver Organoid Metabolic Assays

The liver is among the principal organs for glucose homeostasis and metabolism. Studies of liver metabolism are limited by the inability to expand primary hepatocytes in vitro while maintaining their metabolic functions. Human hepatic three-dimensional (3D) organoids have been established using defined factors, yet hepatic organoids from adult donors showed impaired expansion. We examined conditions to facilitate the expansion of adult donor-derived hepatic organoids (HepAOs) and HepG2 cells in organoid cultures (HepGOs) using combinations of growth factors and small molecules. The expansion dynamics, gluconeogenic and HNF4α expression, and albumin secretion are assessed. The conditions tested allow the generation of HepAOs and HepGOs in 3D cultures. Nevertheless, gluconeogenic gene expression varies greatly between conditions. The organoid expansion rates are limited when including the TGFβ inhibitor A8301, while are relatively higher with Forskolin (FSK) and Oncostatin M (OSM). Notably, expanded HepGOs grown in the optimized condition maintain detectable gluconeogenic expression in a spatiotemporal distribution at 8 weeks. We present optimized conditions by limiting A8301 and incorporating FSK and OSM to allow the expansion of HepAOs from adult donors and HepGOs with gluconeogenic competence. These models increase the repertoire of human hepatic cellular tools available for use in liver metabolic assays.

Patient derived organoids in prostate cancer: improving therapeutic efficacy in precision medicine

With advances in the discovery of the clinical and molecular landscapes of prostate cancer (PCa), implementation of precision medicine-guided therapeutic testing in the clinic has become a priority. Patient derived organoids (PDOs) are three-dimensional (3D) tissue cultures that promise to enable the validation of preclinical drug testing in precision medicine and coclinical trials by modeling PCa for predicting therapeutic responses with a reliable efficacy. We evaluate the advances in 3D culture and PDO use to model clonal heterogeneity and screen for effective targeted therapies, with a focus on the technological advances in generating PDOs. Recent innovations include the utilization of PDOs both in original research and/or correlative studies in clinical trials to examine drug effects within the PCa tumor microenvironment (TME). There has also been a significant improvement with the utilization of various extracellular matrices and single cell assays for the generation and long-term propagation of PDOs. Single cell derived PDOs could faithfully recapitulate the original tumor and reflect the heterogeneity features. While most PDO use for precision medicine understandably involved tissues derived from metastatic patients, we envision that the generation of PDOs from localized PCa along with the incorporation of cells of the TME in tissue models would fulfill the great potential of PDOs in predicting drug clinical benefits. We conclude that single cell derived PDOs reiterate the molecular features of the original tumor and represent a reliable pre-clinical PCa model to understand individual tumors and design tailored targeted therapies.

Novel bone microenvironment model of castration-resistant prostate cancer with chitosan fiber matrix and osteoblasts

The interaction between prostate cancer cells and osteoblasts is essential for the development of bone metastasis. Previously, novel androgen receptor axis-targeted agents (ARATs) were approved for metastatic castration-naïve and non-metastatic castration-resistant prostate cancer (CRPC); both of which are pivotal for investigating the association between the bone microenvironment and tumors. The present study established a novel in vitro 3D microenvironment model that simulated the bone microenvironment of CRPC, and evaluated the drug susceptibility of ARATs and the efficacy of the combination of abiraterone and dutasteride. Green fluorescent protein-transferred C4-2 cells (a CRPC cell line) and red fluorescent protein-transferred human osteoblasts differentiated from human mesenchymal stem cells were co-cultured in chitosan nanofiber matrix-coated culture plates to simulate the 3D scaffold of the bone microenvironment. The growth of C4-2 was quantified using live-cell imaging and the Cell3 iMager duos analysis system. The growth of C4-2 colonies were quantified for a maximum of 30 days. The expression of TGF-β increased and promoted EMT in C4-2 cells co-cultured with osteoblasts, indicating resistance to ARATs. The IC₅₀ of each drug and the combination effect of abiraterone and dutasteride were evaluated using this model. Combination treatment with abiraterone and dutasteride synergistically inhibited the growth of C2-4 colonies compared with individual investigational agents. This could be attributed to the reduction of 3-keto-5α-abiraterone, an androgen receptor agonist. The bone microenvironment model of the present study is unique and useful for evaluating new drug susceptibility testing in prostate cancer cells. This model may help to reveal the unknown mechanisms underlying micro- to clinical bone metastasis in prostate cancer.

Engineering approaches for studying immune-tumor cell interactions and immunotherapy

This review describes recent research that has advanced our understanding of the role of immune cells in the tumor microenvironment (TME) using advanced 3D in vitro models and engineering approaches. The TME can hinder effective eradication of tumor cells by the immune system, but immunotherapy has been able to reverse this effect in some cases. However, patient-to-patient variability in response suggests that we require deeper understanding of the mechanistic interactions between immune and tumor cells to improve response and develop novel therapeutics. Reconstruction of the TME using engineered 3D models allows high-resolution observation of cell interactions while allowing control of conditions such as hypoxia, matrix stiffness, and flow. Moreover, patient-derived organotypic models are an emerging tool for prediction of drug efficacy. This review highlights the importance of modeling and understanding the immune TME and describes new tools for identifying new biological targets, drug testing, and strategies for personalized medicine.

Epidermal Growth Factor Is Essential for the Maintenance of Novel Prostate Epithelial Cells Isolated From Patient-Derived Organoids

Prostate cancer (PCa) is the second leading cause of cancer-related mortality and morbidity among males worldwide. Deciphering the biological mechanisms and molecular pathways involved in PCa pathogenesis and progression has been hindered by numerous technical limitations mainly attributed to the limited number of cell lines available, which do not recapitulate the diverse phenotypes of clinical disease. Indeed, PCa has proven problematic to establish as cell lines in culture due to its heterogeneity which remains a challenge, despite the various in vitro and in vivo model systems available. Growth factors have been shown to play a central role in the complex regulation of cell proliferation among hormone sensitive tumors, such as PCa. Here, we report the isolation and characterization of novel patient-derived prostate epithelial (which we named as AUB-PrC) cells from organoids culture system. We also assessed the role of epidermal growth factor (EGF) in culturing those cells. We profiled the AUB-PrC cells isolated from unaffected and tumor patient samples via depicting their molecular and epithelial lineage features through immunofluorescence staining and quantitative real-time PCR (qRT-PCR), as well as through functional assays and transcriptomic profiling through RNA sequencing. In addition, by optimizing a previously established prostate organoids culture system, we were able to grow human prostate epithelial cells using growth medium and EGF only. With these data collected, we were able to gain insight at the molecular architecture of novel human AUB-PrC cells, which might pave the way for deciphering the mechanisms that lead to PCa development and progression, and ultimately improving prognostic abilities and treatments.

Organoid models of glioblastoma: advances, applications and challenges

The high mortality and poor clinical prognosis of glioblastoma multiforme (GBM) are concerns for many GBM patients as well as clinicians and researchers. The lack of a preclinical model that can easily be established and accurately recapitulate tumour biology and the tumour microenvironment further complicates GBM research and its clinical translation. GBM organoids (GBOs) are promising high-fidelity models that can be applied to model the disease, develop drugs, establish a living biobank, mimic therapeutic responses and explore personalized therapy. However, GBO models face some challenges, including deficient immune responses, absent vascular system and controversial reliability. In recent years, considerable progress has been achieved in the improvement of brain tumour organoid models and research based on such models. In addition to the traditional cultivation method, these models can be cultivated via genetic engineering and co-culture of cerebral organoids and GBM. In this review, we summarize the applications of GBM organoids and related advances and provide our opinions on associated limitations and challenges.

Rapid Processing and Drug Evaluation in Glioblastoma Patient-Derived Organoid Models with 4D Bioprinted Arrays

Glioblastoma is the most common and deadly primary brain malignancy. Despite advances in precision medicine oncology (PMO) allowing the identification of molecular vulnerabilities in glioblastoma, treatment options remain limited, and molecular assays guided by genomic and expression profiling to inform patient enrollment in life-saving trials are lacking. Here, we generate four-dimensional (4D) cell-culture arrays for rapid assessment of drug responses in glioblastoma patient-derived models. The arrays are 3D printed with thermo-responsive shape memory polymer (SMP). Upon heating, the SMP arrays self-transform in time from 3D cell-culture inserts into histological cassettes. We assess the utility of these arrays with glioblastoma cells, gliospheres, and patient derived organoid-like (PDO) models and demonstrate their use with glioblastoma PDOs for assessing drug sensitivity, on-target activity, and synergy in drug combinations. When including genomic and drug testing assays, this platform is poised to offer rapid functional drug assessments for future selection of therapies in PMO.

Emerging Role of Circulating Tumor Cells in Gastric Cancer

With over 1 million incidence cases and more than 780,000 deaths in 2018, gastric cancer (GC) was ranked as the 5th most common cancer and the 3rd leading cause of cancer deaths worldwide. Though several biomarkers, including carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), and cancer antigen 72-4 (CA72-4), have been identified, their diagnostic accuracies were modest. Circulating tumor cells (CTCs), cells derived from tumors and present in body fluids, have recently emerged as promising biomarkers, diagnostically and prognostically, of cancers, including GC. In this review, we present the landscape of CTCs from migration, to the presence in circulation, biologic properties, and morphologic heterogeneities. We evaluated clinical implications of CTCs in GC patients, including diagnosis, prognosis, and therapeutic management, as well as their application in immunotherapy. On the one hand, major challenges in using CTCs in GC were analyzed, from the differences of cut-off values of CTC positivity, to techniques used for sampling, storage conditions, and CTC molecular markers, as well as the unavailability of relevant enrichment and detection techniques. On the other hand, we discussed future perspectives of using CTCs in GC management and research, including the use of circulating tumor microembolies; of CTC checkpoint blockade in immunotherapy; and of organoid models. Despite the fact that there are remaining challenges in techniques, CTCs have potential as novel biomarkers and/or a non-invasive method for diagnostics, prognostics, and treatment monitoring of GC, particularly in the era of precision medicine.

Development of patient-derived xenograft models of prostate cancer for maintaining tumor heterogeneity

Prostate cancer (Pca) is a heterogeneous disease with multiple morphological patterns. Thus, the establishment of a patient-derived xenograft (PDX) model that retains key features of the primary tumor is of great significance. This review demonstrates the characteristics and advantages of the Pca PDX model and summarizes the main factors affecting the establishment of the model. Because this model well recapitulates the diverse heterogeneity observed in the clinic, it was extensively utilized to discover new therapeutic targets, screen drugs, and explore metastatic mechanisms. In the future, clinical phenotype and different stages of the Pca patient might be faithfully reflected by PDX model, which provides tremendous potential for understanding Pca biology and achieving individualized treatment.

Addressing Patient Specificity in the Engineering of Tumor Models

Cancer treatment is challenged by the heterogeneous nature of cancer, where prognosis depends on tumor type and disease stage, as well as previous treatments. Optimal patient stratification is critical for the development and validation of effective treatments, yet pre-clinical model systems are lacking in the delivery of effective individualized platforms that reflect distinct patient-specific clinical situations. Advances in cancer cell biology, biofabrication, and microengineering technologies have led to the development of more complex in vitro three-dimensional (3D) models to act as drug testing platforms and to elucidate novel cancer mechanisms. Mostly, these strategies have enabled researchers to account for the tumor microenvironment context including tumor-stroma interactions, a key factor of heterogeneity that affects both progression and therapeutic resistance. This is aided by state-of-the-art biomaterials and tissue engineering technologies, coupled with reproducible and high-throughput platforms that enable modeling of relevant physical and chemical factors. Yet, the translation of these models and technologies has been impaired by neglecting to incorporate patient-derived cells or tissues, and largely focusing on immortalized cell lines instead, contributing to drug failure rates. While this is a necessary step to establish and validate new models, a paradigm shift is needed to enable the systematic inclusion of patient-derived materials in the design and use of such models. In this review, we first present an overview of the components responsible for heterogeneity in different tumor microenvironments. Next, we introduce the state-of-the-art of current in vitro 3D cancer models employing patient-derived materials in traditional scaffold-free approaches, followed by novel bioengineered scaffold-based approaches, and further supported by dynamic systems such as bioreactors, microfluidics, and tumor-on-a-chip devices. We critically discuss the challenges and clinical prospects of models that have succeeded in providing clinical relevance and impact, and present emerging concepts of novel cancer model systems that are addressing patient specificity, the next frontier to be tackled by the field.

Patient-Derived Xenograft Models of Breast Cancer and Their Application

Recently, patient-derived xenograft (PDX) models of many types of tumors including breast cancer have emerged as a powerful tool for predicting drug efficacy and for understanding tumor characteristics. PDXs are established by the direct transfer of human tumors into highly immunodeficient mice and then maintained by passaging from mouse to mouse. The ability of PDX models to maintain the original features of patient tumors and to reflect drug sensitivity has greatly improved both basic and clinical study outcomes. However, current PDX models cannot completely predict drug efficacy because they do not recapitulate the tumor microenvironment of origin, a failure which puts emphasis on the necessity for the development of the next generation PDX models. In this article, we summarize the advantages and limitations of current PDX models and discuss the future directions of this field.

Patient-derived Models Reveal Impact of the Tumor Microenvironment on Therapeutic Response

Background

Androgen deprivation therapy is a first-line treatment for disseminated prostate cancer (PCa). However, virtually all tumors become resistant and recur as castration-resistant PCa, which has no durable cure. One major hurdle in the development of more effective therapies is the lack of preclinical models that adequately recapitulate the heterogeneity of PCa, significantly hindering the ability to accurately predict therapeutic response.

Objective

To leverage the ex vivo culture method termed patient-derived explant (PDE) to examine the impact of PCa therapeutics on a patient-by-patient basis.

Design setting and participants

Fresh PCa tissue from patients who underwent radical prostatectomy was cultured as PDEs to examine therapeutic response.

Outcome measurements and statistical analysis

The impact of genomic and chemical perturbations in PDEs was assessed using various parameters (eg, AR levels, Ki67 staining, and desmoplastic indices).

Results and limitations

PDE maintained the integrity of the native tumor microenvironment (TME), tumor tissue morphology, viability, and endogenous hormone signaling. Tumor cells in this model system exhibited de novo proliferative capacity. Examination of the native TME in the PDE revealed a first-in-field insight into patient-specific desmoplastic stromal indices and predicted responsiveness to AR-directed therapeutics.

Conclusions

The PDE model allows for a comprehensive evaluation of individual tumors in their native TME to ultimately develop more effective therapeutic regimens tailored to individuals. Discernment of novel stromal markers may provide a basis for applying precision medicine in treating advanced PCa, which would have a transformative effect on patient outcomes.

Patient summary

In this study, an innovative model system was used to more effectively mimic human disease. The patient-derived explant (PDE) system can be used to predict therapeutic response and identify novel targets in advanced disease. Thus, the PDE will be an asset for the development of novel metrics for the implementation of precision medicine in prostate cancer.The patient-derived explant (PDE) model allows for a comprehensive evaluation of individual human tumors in their native tumor microenvironment (TME). TME analysis revealed first-in-field insight into predicted tumor responsiveness to AR-directed therapeutics through evaluation of patient-specific desmoplastic stromal indices.

How to Hit Mesenchymal Stromal Cells and Make the Tumor Microenvironment Immunostimulant Rather Than Immunosuppressive

Experimental evidence indicates that mesenchymal stromal cells (MSCs) may regulate tumor microenvironment (TME). It is conceivable that the interaction with MSC can influence neoplastic cell functional behavior, remodeling TME and generating a tumor cell niche that supports tissue neovascularization, tumor invasion and metastasization. In addition, MSC can release transforming growth factor-beta that is involved in the epithelial-mesenchymal transition of carcinoma cells; this transition is essential to give rise to aggressive tumor cells and favor cancer progression. Also, MSC can both affect the anti-tumor immune response and limit drug availability surrounding tumor cells, thus creating a sort of barrier. This mechanism, in principle, should limit tumor expansion but, on the contrary, often leads to the impairment of the immune system-mediated recognition of tumor cells. Furthermore, the cross-talk between MSC and anti-tumor lymphocytes of the innate and adaptive arms of the immune system strongly drives TME to become immunosuppressive. Indeed, MSC can trigger the generation of several types of regulatory cells which block immune response and eventually impair the elimination of tumor cells. Based on these considerations, it should be possible to favor the anti-tumor immune response acting on TME. First, we will review the molecular mechanisms involved in MSC-mediated regulation of immune response. Second, we will focus on the experimental data supporting that it is possible to convert TME from immunosuppressive to immunostimulant, specifically targeting MSC.

Utility of Glioblastoma Patient-Derived Orthotopic Xenografts in Drug Discovery and Personalized Therapy

Despite substantial effort and resources dedicated to drug discovery and development, new anticancer agents often fail in clinical trials. Among many reasons, the lack of reliable predictive preclinical cancer models is a fundamental one. For decades, immortalized cancer cell cultures have been used to lay the groundwork for cancer biology and the quest for therapeutic responses. However, cell lines do not usually recapitulate cancer heterogeneity or reveal therapeutic resistance cues. With the rapidly evolving exploration of cancer “omics,” the scientific community is increasingly investigating whether the employment of short-term patient-derived tumor cell cultures (two- and three-dimensional) and/or patient-derived xenograft models might provide a more representative delineation of the cancer core and its therapeutic response. Patient-derived cancer models allow the integration of genomic with drug sensitivity data on a personalized basis and currently represent the ultimate approach for preclinical drug development and biomarker discovery. The proper use of these patient-derived cancer models might soon influence clinical outcomes and allow the implementation of tailored personalized therapy. When assessing drug efficacy for the treatment of glioblastoma multiforme (GBM), currently, the most reliable models are generated through direct injection of patient-derived cells or more frequently the isolation of glioblastoma cells endowed with stem-like features and orthotopically injecting these cells into the cerebrum of immunodeficient mice. Herein, we present the key strengths, weaknesses, and potential applications of cell- and animal-based models of GBM, highlighting our experience with the glioblastoma stem-like patient cell-derived xenograft model and its utility in drug discovery.

Circulating tumor cell-derived organoids: Current challenges and promises in medical research and precision medicine

Traditional 2D cell cultures do not accurately recapitulate tumor heterogeneity, and insufficient human cell lines are available. Patient-derived xenograft (PDX) models more closely mimic clinical tumor heterogeneity, but are not useful for high-throughput drug screening. Recently, patient-derived organoid cultures have emerged as a novel technique to fill this critical need. Organoids maintain tumor tissue heterogeneity and drug-resistance responses, and thus are useful for high-throughput drug screening. Among various biological tissues used to produce organoid cultures, circulating tumor cells (CTCs) are promising, due to relative ease of ascertainment. CTC-derived organoids could help to acquire relevant genetic and epigenetic information about tumors in real time, and screen and test promising drugs. This could reduce the need for tissue biopsies, which are painful and may be difficult depending on the tumor location. In this review, we have focused on advances in CTC isolation and organoid culture methods, and their potential applications in disease modeling and precision medicine.