Human acute leukemia cells injected in NOD/LtSz-scid/IL-2Rγnull mice generate a faster and more efficient disease compared to other NOD/scid-related strains

Patient-Derived-Xenografts in Mice: A Preclinical Platform for Cancer Research

The use of patient-derived xenografts (PDXs) has dramatically improved drug development programs. PDXs (1) reproduce the pathological features and the genomic profile of the parental tumors more precisely than other preclinical models, and (2) more faithfully predict therapy response. However, PDXs have limitations. These include the inability to completely capture tumor heterogeneity and the role of the immune system, the low engraftment efficiency of certain tumor types, and the consequences of the human-host interactions. Recently, the use of novel mouse strains and specialized engraftment techniques has enabled the generation of "humanized" PDXs, partially overcoming such limitations. Importantly, establishing, characterizing, and maintaining PDXs is costly and requires a significant regulatory, administrative, clinical, and laboratory infrastructure. In this review, we will retrace the historical milestones that led to the implementation of PDXs for cancer research, review the most recent innovations in the field, and discuss future avenues to tackle deficiencies that still exist.

"Next top" mouse models advancing CTCL research

This review systematically describes the application of in vivo mouse models in studying cutaneous T-cell lymphoma (CTCL), a complex hematological neoplasm. It highlights the diverse research approaches essential for understanding CTCL's intricate pathogenesis and evaluating potential treatments. The review categorizes various mouse models, including xenograft, syngeneic transplantation, and genetically engineered mouse models (GEMMs), emphasizing their contributions to understanding tumor-host interactions, gene functions, and studies on drug efficacy in CTCL. It acknowledges the limitations of these models, particularly in fully replicating human immune responses and early stages of CTCL. The review also highlights novel developments focusing on the potential of skin-targeted GEMMs in studying natural skin lymphoma progression and interactions with the immune system from onset. In conclusion, a balanced understanding of these models' strengths and weaknesses are essential for accelerating the deciphering of CTCL pathogenesis and developing treatment methods. The GEMMs engineered to target specifically skin-homing CD4+ T cells can be the next top mouse models that pave the way for exploring the effects of CTCL-related genes.

Enzalutamide induces cytotoxicity in desmoplastic small round cell tumor independent of the androgen receptor

Desmoplastic Small Round Cell Tumor (DSRCT) is a rare, pediatric cancer caused by the EWSR1::WT1 fusion protein. DSRCT predominantly occurs in males, which comprise 80-90% of the patient population. While the reason for this male predominance remains unknown, one hypothesis is that the androgen receptor (AR) plays a critical role in DSRCT and elevated testosterone levels in males help drive tumor growth. Here, we demonstrate that AR is highly expressed in DSRCT relative to other fusion-driven sarcomas and that the AR antagonists enzalutamide and flutamide reduce DSRCT growth. However, despite these findings, which suggest an important role for AR in DSRCT, we show that DSRCT cell lines form xenografts in female mice at the same rate as male mice and AR depletion does not significantly alter DSRCT growth in vitro. Further, we find that AR antagonists reduce DSRCT growth in cells depleted of AR, establishing an AR-independent mechanism of action. These findings suggest that AR dependence is not the reason for male predominance in DSRCT and that AR-targeted therapies may provide therapeutic benefit primarily through an AR-independent mechanism that requires further elucidation.

Patient-Derived Xenograft Models in Cancer Research: Methodology, Applications, and Future Prospects

Patient-derived xenografts (PDXs) have emerged as a pivotal tool in translational cancer research, addressing limitations of traditional methods and facilitating improved therapeutic interventions. These models involve engrafting human primary malignant cells or tissues into immunodeficient mice, allowing for the investigation of cancer mechanobiology, validation of therapeutic targets, and preclinical assessment of treatment strategies. This chapter provides an overview of PDXs methodology and their applications in both basic cancer research and preclinical studies. Despite current limitations, ongoing advancements in humanized xenochimeric models and autologous immune cell engraftment hold promise for enhancing PDX model accuracy and relevance. As PDX models continue to refine and extend their applications, they are poised to play a pivotal role in shaping the future of translational cancer research.

Advancing CART therapy for acute myeloid leukemia: recent breakthroughs and strategies for future development

Chimeric antigen receptor (CAR) T therapies are being developed for acute myeloid leukemia (AML) on the basis of the results obtained for other haematological malignancies and the need of new treatments for relapsed and refractory AML. The biggest challenge of CART therapy for AML is to identify a specific target antigen, since antigens expressed in AML cells are usually shared with healthy haematopoietic stem cells (HSC). The concomitant expression of the target antigen on both tumour and HSC may lead to on-target/off-tumour toxicity. In this review, we guide researchers to design, develop, and translate to the clinic CART therapies for the treatment of AML. Specifically, we describe what issues have to be considered to design these therapies; what in vitro and in vivo assays can be used to prove their efficacy and safety; and what expertise and facilities are needed to treat and manage patients at the hospital.

Enzalutamide Induces Cytotoxicity in Desmoplastic Small Round Cell Tumor Independent of the Androgen Receptor

Desmoplastic Small Round Cell Tumor (DSRCT) is a rare, pediatric cancer caused by the EWSR1::WT1 fusion protein. DSRCT predominantly occurs in males, which comprise 80-90% of the patient population. While the reason for this male predominance remains unknown, one hypothesis is that the androgen receptor (AR) plays a critical role in DSRCT and elevated testosterone levels in males help drive tumor growth. Here, we demonstrate that AR is highly expressed in DSRCT relative to other fusion-driven sarcomas and that the AR antagonists enzalutamide and flutamide reduce DSRCT growth. However, despite these findings, which suggest an important role for AR in DSRCT, we show that DSRCT cell lines form xenografts in female mice at the same rate as male mice and AR depletion does not significantly alter DSRCT growth in vitro. Further, we find that AR antagonists reduce DSRCT growth in cells depleted of AR, establishing an AR-independent mechanism of action. These findings suggest that AR dependence is not the reason for male predominance in DSRCT and that AR-targeted therapies may provide therapeutic benefit primarily through an AR-independent mechanism that requires further elucidation.

Advances in the Application of Preclinical Models in Photodynamic Therapy for Tumor: A Narrative Review

Photodynamic therapy (PDT) is a non-invasive laser light local treatment that has been utilized in the management of a wide variety of solid tumors. Moreover, the evaluation of efficacy, adverse reactions, the development of new photosensitizers and the latest therapeutic regimens are inseparable from the preliminary exploration in preclinical studies. Therefore, our aim was to better comprehend the characteristics and limitations of these models and to provide a reference for related research.

METHODS

We searched the databases, including PubMed, Web of Science and Scopus for the past 25 years of original research articles on the feasibility of PDT in tumor treatment based on preclinical experiments and animal models. We provided insights into inclusion and exclusion criteria and ultimately selected 40 articles for data synthesis.

RESULTS

After summarizing and comparing the methods and results of these studies, the experimental model selection map was drawn. There are 7 main preclinical models, which are used for different research objectives according to their characteristics.

CONCLUSIONS

Based on this narrative review, preclinical experimental models are crucial to the development and promotion of PDT for tumors. The traditional animal models have some limitations, and the emergence of organoids may be a promising new insight.

Generation and Characterization of a Humanized Lung Xenograft Mouse Model for Studying Henipavirus Pathogenesis

The development of humanized mouse models has recently opened new avenues in the field of infectious diseases. These models allow research on many human viruses that were once difficult to study, because finding suitable animal models of infection can be challenging, cost prohibitive, and often do not entirely recapitulate all parameters of the disease. Here, we describe the procedure of human immune system reconstitution (humanization) of NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice by the bone marrow, liver, and thymus (BLT) reconstitution method as well as the process of human lung engraftment. We then describe how to infect these human lung grafts with the paramyxovirus Nipah virus (NiV) that can cause lethal respiratory disease in humans, and for which there is only limited understanding of pathogenesis to acute lung injury.

Panobinostat (LBH589) increase survival in adult xenografic model of acute lymphoblastic leukemia with t(4;11) but promotes antagonistic effects in combination with MTX and 6MP

Patients diagnosed with acute lymphoblastic leukemia (ALL) bearing t(4;11)/MLL-AF4 have aggressive clinical features, poor prognosis and there is an urgent need for new therapies to improve outcomes. Panobinostat (LBH589) has been identified as a potential therapeutic agent for ALL with t(4;11) and studies suggest that the antineoplastic effects are associated with reduced MLL-AF4 fusion protein and reduced expression of HOX genes. Here, we evaluated the in vitro effects of the combination of LBH589 with methotrexate (MTX) or 6-mercaptopurine (6MP) by cell proliferation assays and Calcusyn software in ALL cell line (RS4;11); the in vivo effects of LBH589 in xenotransplanted NOD-scid IL2Rgamma^null mice measuring human lymphoblasts by flow cytometry; and the expression of HOX genes by qPCR after treatment in an adult model of ALL with t(4;11). LBH589 combination with MTX or 6MP did not promote synergistic effects in RS4;11 cell line. LBH589 treatment leads to increased overall survival and reduction of blasts in xenotransplanted mice but caused no significant changes in HOXA7, HOXA9, HOXA10, and MEIS1 expression. The LBH589, alone, showed promising antineoplastic effects in vivo and may represent a potential agent for chemotherapy in ALL patients with t(4;11).

CD34+CD10+CD19− Cells in Patients with Unhealthy Alcohol Use Stimulate the M2b Monocyte Polarization

M2b monocytes commonly isolated from patients with unhealthy alcohol use (Alc) have been described as cells that make the host susceptible to opportunistic infections. CD34⁺CD10⁺CD19⁻ cells are multilineage progenitors of CD19⁺ cells, and we show that the effect of these cells from the peripheral blood on M2b monocyte polarization differed between healthy donors and Alc in this study. In healthy donors, these cells consistently differentiated into high-mobility group box-1 (HMGB1)-nonproducing cells (CD19⁺ cells) in response to retinoic acid (RA). However, owing to the lack of expression of RA receptor (RAR), these cells from Alc failed to differentiate into CD19⁺ cells under the same RA stimulation. Conditioned medium (CM) of these cells from Alc induced the polarization of M2b monocytes, which increases the susceptibility of hosts to opportunistic infections in Alc. When the alcoholic individuals were subjected to 2 weeks of abstinence from alcohol, these cells from Alc recovered their RAR expression and differentiated into CD19⁺ cells. Moreover, the CM of these cells from Alc after abstinence lost its ability to induce M2b monocyte polarization. These results indicate that these cells from Alc have different properties from those of healthy donors. In Alc, these cells without RAR stimulate M2b monocyte polarization through the production of HMGB1.

Non-clinical assessment of safety, biodistribution and tumorigenicity of human mesenchymal stromal cells

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Good safety profile of mesenchymal stromal cells (MSCs) without toxicity findings.

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MSC biodistribution showed primary distribution to the lung and short persistence.

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No tumor formation observed after 6 months of repeated MSC dosing.

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qPCR and in situ hybridization were combined for the detection of MSCs.

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Data allow progression into clinical trials for acute Graft-versus-Host disease.

Guidelines regulating the development of advanced therapy medicinal products (ATMPs) request nonclinical data for toxicity, biodistribution and tumorigenicity before mesenchymal stromal cell (MSC) products can be administered in large clinical trials. We assessed the biodistribution/persistence, safety and tumorigenicity of MC0518, a human allogeneic MSC product from pooled bone marrow mononuclear cells of eight healthy, adult, unrelated donors, which is currently investigated for the treatment of steroid-refractory acute Graft-versus-Host Disease (aGvHD) after hematopoietic stem cell transplantation. In our GLP studies, immuno-deficient mice were administered repeat doses of MC0518 (once weekly for 6 weeks, i.v.) at doses exceeding the proposed human clinical dose 20-60-fold. No signs of toxicity were observed in the combined biodistribution/toxicity study. Human MSCs in mouse tissues were detected by quantitative PCR (qPCR) and in situ hybridization (ISH). MC0518 showed initial trapping in the lung, occasional distribution into other organs and low tissue persistence beyond 24 h after application. No MSC-induced tumors of human origin were identified after a follow-up of six months. Additionally, we found that the combination of different detection methods (qPCR and ISH) is crucial for a reliable interpretation of biodistribution results. Our data suggest that MC0518 is safe for use in human.

Characterization of a xenograft model for anti-CD19 CAR T cell studies

PURPOSE

Chimeric antigen receptor (CAR) T cell development for B cell malignancies treatment has triggered a paradigm shift in oncology. The development of anti-CD19 CAR T cells relies primarily on a panel of cell line-derived xenograft models, including Raji cells; however, the behavior of this model is under debate. We attempted to characterize this lymphoma model and propose outcome measures for CAR T cell studies METHODS: Raji cell line was inoculated into NOG mice via intra-venous (IV), intra-peritoneal (IP), and subcutaneous (SC) routes with different inoculum sizes, and consequent clinical and histopathological outcomes were assessed.

RESULTS

Inoculum sizes of 10⁵-10⁶ resulted in a complete take rate. The mice with IV and SC-inoculated Raji cells presented the shortest and longest survival among lymphoma-bearing mice, respectively (P < 0.01). The IP group had the highest number of both infiltrated organs (P < 0.05; compared to SC) and involvement of lymphatic sites (P < 0.05; compared to IV). The number of lymphoma lesions on the liver was higher in the IV compared to IP (P < 0.001) and SC (P < 0.05).

CONCLUSION

We demonstrate that the Raji cell line inoculation route could determine the xenograft model system behavior in terms of survival, tumor burden, and dissemination pattern and gives the model the specific features suitable for testing the specific hypothesis in CAR T cell therapy. We also conclude outcome measures for CAR T cell studies that do not require imaging techniques.

An Experimental and Computational Protocol to Study Cell Proliferation in Human Acute Myeloid Leukemia Xenografts

Acute myeloid leukemia (AML) is a highly frequent hematological malignancy, characterized by clinical and biological diversity, along with high relapse and mortality rates. The inherent functional and genetic intra-tumor heterogeneity in AML is thought to play an important role in disease recurrence and resistance to chemotherapy. Patient-derived xenograft (PDX) models preserve important features of the original tumor, allowing, at the same time, experimental manipulation and in vivo amplification of the human cells. Here we present a detailed protocol for the generation of fluorescently labeled AML PDX models to monitor cell proliferation kinetics in vivo, at the single-cell level. Although experimental protocols for cell proliferation studies are well established and widespread, they are not easily applicable to in vivo contexts, and the analysis of related time-series data is often complex to achieve. To overcome these limitations, model-driven approaches can be exploited to investigate different aspects of cell population dynamics. Among the existing approaches, the ProCell framework is able to perform detailed and accurate stochastic simulations of cell proliferation, relying on flow cytometry data. In particular, by providing an initial and a target fluorescence histogram, ProCell automatically assesses the validity of any user-defined scenario of intra-tumor heterogeneity, that is, it is able to infer the proportion of various cell subpopulations (including quiescent cells) and the division interval of proliferating cells. Here we explain the protocol in detail, providing a description of our methodology for the conditional expression of H2B-GFP in human AML xenografts, data processing by flow cytometry, and the final elaboration in ProCell.

Modelling t(8;21) acute myeloid leukaemia - What have we learned?

Acute myeloid leukaemia (AML) is a heterogeneous haematopoietic malignancy caused by recurrent mutations in haematopoietic stem and progenitor cells that affect both the epigenetic regulatory machinery and signalling molecules. The t(8;21) or RUNX1‐RUNX1T1 translocation generates the RUNX1‐ETO chimeric transcription factor which primes haematopoietic stem cells for further oncogenic mutational events that in their sum cause overt disease. Significant progress has been made in generating both in vitro and in vivo model systems to recapitulate t(8;21) AML which are crucial for the understanding of the biology of the disease and the development of effective treatment. This review provides a comprehensive overview of the in vivo and in vitro model systems that were developed to gain insights into the molecular mechanisms of RUNX1‐ETO oncogenic activity and their contribution to the advancement of knowledge in the t(8;21) AML field. Such models include transgenic mice, patient‐derived xenografts, RUNX1‐ETO transduced human progenitor cells, cell lines and human embryonic stem cell model systems, making the t(8;21) as one of the well‐characterized sub‐type of AML at the molecular level.

Programmed Death 1 Ligand Expression in the Monocytes of Patients with Hepatocellular Carcinoma Depends on Tumor Progression

Monocytes (CD14+ cells) from advanced-stage hepatocellular carcinoma (HCC) patients express programmed death 1 ligand (PD-L)/PD-1 and suppress the host antitumor immune response. However, it is unclear whether cancer progression is associated with CD14+ cells. We compared CD14+ cell properties before and after cancer progression in the same HCC patients and examined their role in antitumor immunity. CD14+ cells were isolated from 15 naïve early-stage HCC patients before treatment initiation and after cancer progression to advanced stages. Although CD14+ cells from patients at early HCC stages exhibited antitumor activity in humanized murine chimera, CD14+ cells from the same patients after progression to advanced stages lacked this activity. Moreover, CD14+ cells from early HCC stages scantly expressed PD-L1 and PD-L2 and produced few cytokines, while CD14+ cells from advanced stages showed increased PD-L expression and produced IL-10 and CCL1. CD14+ cells were also isolated from five naïve advanced-stage HCC patients before treatment as well as after treatment-induced tumor regression. The CD14+ cells from patients with advanced-stage HCC expressed PD-L expressions, produced IL-10 and CCL1, and exhibited minimal tumoricidal activity. After treatment-induced tumor regression, CD14+ cells from the same patients did not express PD-Ls, failed to produce cytokines, and recovered tumoricidal activity. These results indicate that PD-L expression as well as CD14+ cell phenotype depend on the tumor stage in HCC patients. PD-L expressions of monocytes may be used as a new marker in the classification of cancer progression in HCC.

Comparing the fate of brain metastatic breast cancer cells in different immune compromised mice with cellular magnetic resonance imaging

Metastasis is the leading cause of mortality in breast cancer patients, with brain metastases becoming increasingly prevalent. Studying this disease is challenging due to the limited experimental models and methods available. Here, we used iron-based cellular MRI to track the fate of a mammary carcinoma cell line (MDA-MB-231-BR) in vivo to characterize the growth of brain metastases in the nude and severely immune-compromised NOD/SCID/ILIIrg-/- (NSG) mouse. Nude and NSG mice received injections of iron-labeled MDA-MB-231-BR cells. Images were acquired with a 3T MR system and assessed for signal voids and metastases. The percentage of signal voids and the number and volume of metastases were quantified. Ex vivo imaging of the liver, histology, and immunofluorescence labeling was performed. Brain metastases grew more rapidly in NSG mice. At day 21 post cell injection, the average number of brain tumors in NSG mice was approximately four times greater than in nude mice. The persistence of iron-labeled cells, visualized as signal voids by MRI, was also examined. The percentage of voids decreased significantly over time for both nude and NSG mice. Body images revealed that the NSG mice also had metastases in the liver, lungs, and lymph nodes while tumors were only detected in the brains of nude mice. This work demonstrates the advantages of using the highly immune-compromised NSG mouse to study breast cancer metastasis, treatments aimed at inhibiting metastasis and outgrowth of breast cancer metastases in multiple organs, and the role that imaging can play toward credentialing these models that cannot be done with other in vitro or histopathologic methods alone.

Patient-Derived Orthotopic Xenograft Models of Pediatric Brain Tumors: In a Mature Phase or Still in Its Infancy?

In recent years, molecular profiling has led to the discovery of an increasing number of brain tumor subtypes, and associated therapeutic targets. These molecular features have been incorporated in the 2016 new World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS), which now distinguishes tumor subgroups not only histologically, but also based on molecular characteristics. Despite an improved diagnosis of (pediatric) tumors in the CNS however, the survival of children with malignant brain tumors still is far worse than for those suffering from other types of malignancies. Therefore, new treatments need to be developed, based on subgroup-specific genetic aberrations. Here, we provide an overview of the currently available orthotopic xenograft models for pediatric brain tumor subtypes as defined by the 2016 WHO classification, to facilitate the choice of appropriate animal models for the preclinical testing of novel treatment strategies, and to provide insight into the current gaps and challenges.

A two-pronged anti-leukemic agent based on a hyaluronic acid–green tea catechin conjugate for inducing targeted cell death and terminal differentiation

A two-pronged anti-leukemic approach for leukemic cell elimination and differentiation is demonstrated using a hyaluronic acid–green tea catechin conjugate.

Mouse Tumor-Bearing Models as Preclinical Study Platforms for Oral Squamous Cell Carcinoma

Preclinical animal models of oral squamous cell carcinoma (OSCC) have been extensively studied in recent years. Investigating the pathogenesis and potential therapeutic strategies of OSCC is required to further progress in this field, and a suitable research animal model that reflects the intricacies of cancer biology is crucial. Of the animal models established for the study of cancers, mouse tumor-bearing models are among the most popular and widely deployed for their high fertility, low cost, and molecular and physiological similarity to humans, as well as the ease of rearing experimental mice. Currently, the different methods of establishing OSCC mouse models can be divided into three categories: chemical carcinogen-induced, transplanted and genetically engineered mouse models. Each of these methods has unique advantages and limitations, and the appropriate application of these techniques in OSCC research deserves our attention. Therefore, this review comprehensively investigates and summarizes the tumorigenesis mechanisms, characteristics, establishment methods, and current applications of OSCC mouse models in published papers. The objective of this review is to provide foundations and considerations for choosing suitable model establishment methods to study the relevant pathogenesis, early diagnosis, and clinical treatment of OSCC.

Improved chemotherapy modeling with RAG-based immune deficient mice

We have previously characterized an acute myeloid leukemia (AML) chemotherapy model for SCID-based immune deficient mice (NSG and NSGS), consisting of 5 days of cytarabine (AraC) and 3 days of anthracycline (doxorubicin), to simulate the standard 7+3 chemotherapy regimen many AML patients receive. While this model remains tractable, there are several limitations, presumably due to the constitutional Pkrdc^scid (SCID, severe combined immune deficiency) mutation which affects DNA repair in all tissues of the mouse. These include the inability to combine preconditioning with subsequent chemotherapy, the inability to repeat chemotherapy cycles, and the increased sensitivity of the host hematopoietic cells to genotoxic stress. Here we attempt to address these drawbacks through the use of alternative strains with RAG-based immune deficiency (NRG and NRGS). We find that RAG-based mice tolerate a busulfan preconditioning regimen in combination with either AML or 4-drug acute lymphoid leukemia (ALL) chemotherapy, expanding the number of samples that can be studied. RAG-based mice also tolerate multiple cycles of therapy, thereby allowing for more aggressive, realistic modeling. Furthermore, standard AML therapy in RAG mice was 3.8-fold more specific for AML cells, relative to SCID mice, demonstrating an improved therapeutic window for genotoxic agents. We conclude that RAG-based mice should be the new standard for preclinical evaluation of therapeutic strategies involving genotoxic agents.

New anti-IL-7Rα monoclonal antibodies show efficacy against T cell acute lymphoblastic leukemia in pre-clinical models

Pediatric T cell acute lymphoblastic leukemia (T-ALL) cells frequently contain mutations in the interleukin-7 (IL-7) receptor pathway or respond to IL-7 itself. To target the IL-7 receptor on T-ALL cells, murine monoclonal antibodies (MAbs) were developed against the human IL-7Rα chain and chimerized with human IgG1 constant regions. Crystal structures demonstrate that the two MAbs bound different IL-7Rα epitopes. The MAbs mediated antibody-dependent cell-mediated cytotoxicity (ADCC) against patient-derived xenograft (PDX) T-ALL cells, which was improved by combining two MAbs. In vivo, the MAbs showed therapeutic efficacy via ADCC-dependent and independent mechanisms in minimal residual and established disease. PDX T-ALL cells that relapsed following a course of chemotherapy displayed elevated IL-7Rα, and MAb treatment is effective against relapsing disease, suggesting the use of anti-IL7Rα MAbs in relapsed T-ALL patients or patients that do not respond to chemotherapy.

A Critical Review of Animal Models Used in Acute Myeloid Leukemia Pathophysiology

Acute myeloid leukemia (AML) is one of the most frequent, complex, and heterogeneous hematological malignancies. AML prognosis largely depends on acquired cytogenetic, epigenetic, and molecular abnormalities. Despite the improvement in understanding the biology of AML, survival rates remain quite low. Animal models offer a valuable tool to recapitulate different AML subtypes, and to assess the potential role of novel and known mutations in disease progression. This review provides a comprehensive and critical overview of select available AML animal models. These include the non-mammalian Zebrafish and Drosophila models as well as the mammalian rodent systems, comprising rats and mice. The suitability of each animal model, its contribution to the advancement of knowledge in AML pathophysiology and treatment, as well as its advantages and limitations are discussed. Despite some limitations, animal models represent a powerful approach to assess toxicity, and permit the design of new therapeutic strategies.

Regeneration Enhances Metastasis: A Novel Role for Neurovascular Signaling in Promoting Melanoma Brain Metastasis

Neural repair after stroke involves initiation of a cellular proliferative program in the form of angiogenesis, neurogenesis, and molecular growth signals in the surrounding tissue elements. This cellular environment constitutes a niche in which regeneration of new blood vessels and new neurons leads to partial tissue repair after stroke. Cancer metastasis has similar proliferative cellular events in the brain and other organs. Do cancer and CNS tissue repair share similar cellular processes? In this study, we identify a novel role of the regenerative neurovascular niche induced by stroke in promoting brain melanoma metastasis through enhancing cellular interactions with surrounding niche components. Repair-mediated neurovascular signaling induces metastatic cells to express genes crucial to metastasis. Mimicking stroke-like conditions in vitro displays an enhancement of metastatic migration potential and allows for the determination of cell-specific signals produced by the regenerative neurovascular niche. Comparative analysis of both in vitro and in vivo expression profiles reveals a major contribution of endothelial cells in mediating melanoma metastasis. These results point to a previously undiscovered role of the regenerative neurovascular niche in shaping the tumor microenvironment and brain metastatic landscape.

Current Perspectives on Nasopharyngeal Carcinoma

Of the ~129,079 new cases of nasopharyngeal carcinoma (NPC) and 72,987 associated deaths estimated for 2018, the majority will be geographically localized to South East Asia, and likely to show an upward trend annually. It is thought that disparities in dietary habits, lifestyle, and exposures to harmful environmental factors are likely the root cause of NPC incidence rates to differ geographically. Genetic differences due to ethnicity and the Epstein Barr virus (EBV) are likely contributing factors. Pertinently, NPC is associated with poor prognosis which is largely attributed to lack of awareness of the salient symptoms of NPC. These include nose hemorrhage and headaches and coupled with detection and the limited therapeutic options. Treatment options include radiotherapy or chemotherapy or combination of both. Surgical excision is generally the last option considered for advanced and metastatic disease, given the close proximity of nasopharynx to brain stem cell area, major blood vessels, and nerves. To improve outcome of NPC patients, novel cellular and in vivo systems are needed to allow an understanding of the underling molecular events causal for NPC pathogenesis and for identifying novel therapeutic targets and effective therapies. While challenges and gaps in current NPC research are noted, some advances in targeted therapies and immunotherapies targeting EBV NPCs are discussed in this chapter, which may offer improvements in outcome of NPC patients.

The bone microenvironment promotes tumor growth and tissue perfusion compared with striated muscle in a preclinical model of prostate cancer in vivo

Background

Prostate cancer-related morbidity is associated with its preferential spread to the bone. Although the molecular interactions between the bone microenvironment and cancer cells have been researched extensively, the relevance of the microvascular properties of prostate cancer bone metastases remains largely unknown. Most preclinical studies focusing on microvascular analyses are based on heterotopic tumor implantation, whereas the impact of the microenvironment on site-specific growth behavior and angiogenesis is rarely addressed.

Methods

The microvascular changes associated with tumor growth in bone and soft tissue were characterized by implanting single cell suspensions of LnCap, Du145, and Pc3 cells into the femur (femur window) or striated muscle (dorsal skinfold chamber) of NSG mice. Tumor growth and the local microvasculature were analyzed for 21 days using intravital fluorescence microscopy.

Results

The results showed a higher engraftment of tumor cells in bone than in striated muscle associated with accelerated growth of LnCap cells and Pc3 cells. Permeability, blood flow, and tissue perfusion rates were greater in bone than in striated muscle. Du145 cells showed similar growth behavior in both tissues with similar vascular properties. The bone microenvironment facilitated tumor engraftment and growth. Increased microvascular density in striated muscle led to a higher tumor burden during early growth, whereas the increased perfusion promoted later prostate cancer growth in bone.

Conclusions

Monitoring prostate cancer microcirculation in bone and soft tissue may be useful to evaluate the organ-specific efficacy of new treatments.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4905-5) contains supplementary material, which is available to authorized users.

Humanized Mouse Models for the Preclinical Assessment of Cancer Immunotherapy

Immunotherapy is one of the most exciting recent breakthroughs in the field of cancer treatment. Many different approaches are being developed and a number have already gained regulatory approval or are under investigation in clinical trials. However, learning from the past, preclinical animal models often insufficiently reflect the physiological situation in humans, which subsequently causes treatment failures in clinical trials. Due to species-specific differences in most parts of the immune system, the transfer of knowledge from preclinical studies to clinical trials is eminently challenging. Human tumor cell line-based or patient-derived xenografts in immunocompromised mice have been successfully applied in the preclinical testing of cytotoxic or molecularly targeted agents, but naturally these systems lack the human immune system counterpart. The co-transplantation of human peripheral blood mononuclear cells or hematopoietic stem cells is employed to overcome this limitation. This review summarizes some important aspects of the different available tumor xenograft mouse models, their history, and their implementation in drug development and personalized therapy. Moreover, recent progress, opportunities and limitations of different humanized mouse models will be discussed.

Cystatin C takes part in melanoma-microglia cross-talk: possible implications for brain metastasis

The development of melanoma brain metastasis is largely dependent on mutual interactions between the melanoma cells and cells in the brain microenvironment. Here, we report that the extracellular cysteine protease inhibitor cystatin C (CysC) is involved in these interactions. Microglia-derived factors upregulated CysC secretion by melanoma. Similarly, melanoma-derived factors upregulated CysC secretion by microglia. Whereas CysC enhanced melanoma cell migration through a layer of brain endothelial cells, it inhibited the migration of microglia cells toward melanoma cells. CysC was also found to promote the formation of melanoma three-dimensional structures in matrigel. IHC analysis revealed increased expression levels of CysC in the brain of immune-deficient mice bearing xenografted human melanoma brain metastasis compared to the brain of control mice. Based on these in vitro and in vivo experiments we hypothesize that CysC promotes melanoma brain metastasis. Increased expression levels of CysC were detected in the regenerating brain of mice after stroke. Post-stroke brain with melanoma brain metastasis showed an even stronger expression of CysC. The in vitro induction of stroke-like conditions in brain microenvironmental cells increased the levels of CysC in the secretome of microglia cells, but not in the secretome of brain endothelial cells. The similarities between melanoma brain metastasis and stroke with respect to CysC expression by and secretion from microglia cells suggest that CysC may be involved in shared pathways between brain metastasis and post-stroke regeneration. This manifests the tendency of tumor cells to highjack physiological molecular pathways in their progression.

Human pancreatic cancer xenografts recapitulate key aspects of cancer cachexia

Cancer cachexia represents a debilitating syndrome that diminishes quality of life and augments the toxicities of conventional treatments. Cancer cachexia is particularly debilitating in patients with pancreatic cancer (PC). Mechanisms responsible for cancer cachexia are under investigation and are largely derived from observations in syngeneic murine models of cancer which are limited in PC. We evaluate the effect of human PC cells on both muscle wasting and the systemic inflammatory milieu potentially contributing to PC-associated cachexia. Specifically, human PC xenografts were generated by implantation of pancreatic cancer cells, L3.6pl and PANC-1, either in the flank or orthotopically within the pancreas. Mice bearing orthotopic xenografts demonstrated significant muscle wasting and atrophy-associated gene expression changes compared to controls. Further, despite the absence of adaptive immunity, splenic tissue from orthotopically engrafted mice demonstrated elevations in several pro-inflammatory cytokines associated with cancer cachexia, including TNFα, IL1β, IL6 and KC (murine IL8 homologue), when compared to controls. Therefore, data presented here support further investigation into the complexity of cancer cachexia in PC to identify potential targets for this debilitating syndrome.

Targeting BCL-2 and ABL/LYN in Philadelphia chromosome-positive acute lymphoblastic leukemia

Treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+)ALL) remains a challenge. Although the addition of targeted tyrosine kinase inhibitors (TKIs) to standard cytotoxic therapy has greatly improved upfront treatment, treatment-related morbidity and mortality remain high. TKI monotherapy provides only temporary responses and renders patients susceptible to the development of TKI resistance. Thus, identifying agents that could enhance the activity of TKIs is urgently needed. Recently, a selective inhibitor of B cell lymphoma 2 (BCL-2), ABT-199 (venetoclax), has shown impressive activity against hematologic malignancies. We demonstrate that the combination of TKIs with venetoclax is highly synergistic in vitro, decreasing cell viability and inducing apoptosis in Ph(+)ALL. Furthermore, the multikinase inhibitors dasatinib and ponatinib appear to have the added advantage of inducing Lck/Yes novel tyrosine kinase (LYN)-mediated proapoptotic BCL-2-like protein 11 (BIM) expression and inhibiting up-regulation of antiapoptotic myeloid cell leukemia 1 (MCL-1), thereby potentially overcoming the development of venetoclax resistance. Evaluation of the dasatinib-venetoclax combination for the treatment of primary Ph(+)ALL patient samples in xenografted immunodeficient mice confirmed the tolerability of this drug combination and demonstrated its superior antileukemic efficacy compared to either agent alone. These data suggest that the combination of dasatinib and venetoclax has the potential to improve the treatment of Ph(+)ALL and should be further evaluated for patient care.

Higher-Level Pathway Objectives of Epigenetic Therapy: A Solution to the p53 Problem in Cancer

Searches for effective yet nontoxic oncotherapies are searches for exploitable differences between cancer and normal cells. In its core of cell division, cancer resembles normal life, coordinated by the master transcription factor MYC. Outside of this core, apoptosis and differentiation programs, which dominantly antagonize MYC to terminate cell division, necessarily differ between cancer and normal cells, as apoptosis is suppressed by biallelic inactivation of the master regulator of apoptosis, p53, or its cofactor p16/CDKN2A in approximately 80% of cancers. These genetic alterations impact therapy: conventional oncotherapy applies stress upstream of p53 to upregulate it and causes apoptosis (cytotoxicity)-a toxic, futile intent when it is absent or nonfunctional. Differentiation, on the other hand, cannot be completely suppressed because it is a continuum along which all cells exist. Neoplastic evolution stalls advances along this continuum at its most proliferative points-in lineage-committed progenitors that have division times measured in hours compared with weeks for tissue stem cells. This differentiation arrest is by mutations/deletions in differentiation-driving transcription factors or their coactivators that shift balances of gene-regulating protein complexes toward corepressors that repress instead of activate hundreds of terminal differentiation genes. That is, malignant proliferation without differentiation, also referred to as cancer "stem" cell self-renewal, hinges on druggable corepressors. Inhibiting these corepressors (e.g., DNMT1) releases p53-independent terminal differentiation in cancer stem cells but preserves self-renewal of normal stem cells that express stem cell transcription factors. Thus, epigenetic-differentiation therapies exploit a fundamental distinction between cancer and normal stem cell self-renewal and have a pathway of action downstream of genetic defects in cancer, affording favorable therapeutic indices needed for clinical progress.

Inhibition of histone deacetylase 6 (HDAC6) protects against vincristine-induced peripheral neuropathies and inhibits tumor growth

As cancer is becoming more and more a chronic disease, a large proportion of patients is confronted with devastating side effects of certain anti-cancer drugs. The most common neurological complications are painful peripheral neuropathies. Chemotherapeutics that interfere with microtubules, including plant-derived vinca-alkaloids such as vincristine, can cause these chemotherapy-induced peripheral neuropathies (CIPN). Available treatments focus on symptom alleviation and pain reduction rather than prevention of the neuropathy. The aim of this study was to investigate the potential of specific histone deacetylase 6 (HDAC6) inhibitors as a preventive therapy for CIPN using multiple rodent models for vincristine-induced peripheral neuropathies (VIPN). HDAC6 inhibition increased the levels of acetylated α-tubulin in tissues of rodents undergoing vincristine-based chemotherapy, which correlates to a reduced severity of the neurological symptoms, both at the electrophysiological and the behavioral level. Mechanistically, disturbances in axonal transport of mitochondria is considered as an important contributing factor in the pathophysiology of VIPN. As vincristine interferes with the polymerization of microtubules, we investigated whether disturbances in axonal transport could contribute to VIPN. We observed that increasing α-tubulin acetylation through HDAC6 inhibition restores vincristine-induced defects of axonal transport in cultured dorsal root ganglion neurons. Finally, we assured that HDAC6-inhibition offers neuroprotection without interfering with the anti-cancer efficacy of vincristine using a mouse model for acute lymphoblastic leukemia. Taken together, our results emphasize the therapeutic potential of HDAC6 inhibitors with beneficial effects both on vincristine-induced neurotoxicity, as well as on tumor proliferation.

The microenvironment in myelodysplastic syndromes: Niche-mediated disease initiation and progression

Myelodysplastic syndromes (MDSs) are clonal disorders of hematopoietic stem and progenitor cells and represent the most common cause of acquired marrow failure. Hallmarked by ineffective hematopoiesis, dysplastic marrow, and risk of transformation to acute leukemia, MDS remains a poorly treated disease. Although identification of hematopoietic aberrations in human MDS has contributed significantly to our understanding of MDS pathogenesis, evidence now identify the bone marrow microenvironment (BMME) as another key contributor to disease initiation and progression. With improved understanding of the BMME, we are beginning to refine the role of the hematopoietic niche in MDS. Despite genetic diversity in MDS, interaction between MDS and the BMME appears to be a common disease feature and therefore represents an appealing therapeutic target. Further understanding of the interdependent relationship between MDS and its niche is needed to delineate the mechanisms underlying hematopoietic failure and how the microenvironment can be targeted clinically. This review provides an overview of data from human MDS and murine models supporting a role for BMME dysfunction at several steps of disease pathogenesis. Although no models or human studies so far have combined all of these findings, we review current data identifying BMME involvement in each step of MDS pathogenesis organized to reflect the chronology of BMME contribution as the normal hematopoietic system becomes myelodysplastic and MDS progresses to marrow failure and transformation. Although microenvironmental heterogeneity and dysfunction certainly add complexity to this syndrome, data are already demonstrating that targeting microenvironmental signals may represent novel therapeutic strategies for MDS treatment.

Generation and use of a humanized bone-marrow-ossicle niche for hematopoietic xenotransplantation into mice

Xenotransplantation is frequently used to study normal and malignant hematopoiesis of human cells. However, conventional mouse xenotransplantation models lack essential human-specific bone-marrow (BM)-microenvironment-derived survival, proliferation, and self-renewal signals for engraftment of normal and malignant blood cells. As a consequence, many human leukemias and other hematologic disorders do not robustly engraft in these conventional models. Here, we describe a complete workflow for the generation of humanized ossicles with an accessible BM microenvironment that faithfully recapitulates normal BM niche morphology and function. The ossicles, therefore, allow for accelerated and superior engraftment of primary patient-derived acute myeloid leukemia (AML) and other hematologic malignancies such as myelofibrosis (MF) in mice. The humanized ossicles are formed by in situ differentiation of BM-derived mesenchymal stromal cells (MSCs). Human hematopoietic cells can subsequently be transplanted directly into the ossicle marrow space or by intravenous injection. Using this method, a humanized engraftable BM microenvironment can be formed within 6-10 weeks. Engraftment of human hematopoietic cells can be evaluated by flow cytometry 8-16 weeks after transplantation. This protocol describes a robust and reproducible in vivo methodology for the study of normal and malignant human hematopoiesis in a more physiologic setting.

In vivo functional and morphological characterization of bone and striated muscle microcirculation in NSG mice

Organ-specific microcirculation plays a central role in tumor growth, tumor cell homing, tissue engineering, and wound healing. Mouse models are widely used to study these processes; however, these mouse strains often possess unique microhemodynamic parameters, making it difficult to directly compare experiments. The full functional characterization of bone and striated muscle microcirculatory parameters in non-obese diabetic-severe combined immunodeficiency/y-chain; NOD-Prkds IL2rg (NSG) mice has not yet been reported. Here, we established either a dorsal skinfold chamber or femur window in NSG mice (n = 23), allowing direct analysis of microcirculatory parameters in vivo by intravital fluorescence microscopy at 7, 14, 21, and 28 days after chamber preparation. Organ-specific differences were observed. Bone had a significantly lower vessel density but a higher vessel diameter than striated muscle. Bone also showed higher effective vascular permeability than striated muscle. The centerline velocity values were similar in the femur window and dorsal skinfold chamber, with a higher volumetric blood flow in bone. Interestingly, bone and striated muscle showed similar tissue perfusion rates. Knowledge of physiological microhemodynamic values of bone and striated muscle in NSG mice makes it possible to analyze pathophysiological processes at these anatomic sites, such as tumor growth, tumor metastasis, and tumor microcirculation, as well as the response to therapeutic agents.

CRISPR/Cas9-Mediated Deletion of Foxn1 in NOD/SCID/IL2rg-/- Mice Results in Severe Immunodeficiency

Immunodeficient mice engrafted with either normal or cancerous human cells are widely used in basic and translational research. In particular, NOD/SCID/IL2rg^−/− mice can support the growth of various types of human cancer cells. However, the hairs of these mice interfere with the observation and imaging of engrafted tissues. Therefore, novel hairless strains exhibiting comparable immunodeficiency would be beneficial. Recently, the CRISPR/Cas9 system has been used for efficient multiplexed genome editing. In the present study, we generated a novel strain of nude NOD/SCID/IL2rg^−/− (NSIN) mice by knocking out Foxn1 from NOD/SCID/IL2rg^−/− (NSI) mice using the CRISPR/Cas9 system. The NSIN mice were deficient in B, T, and NK cells and not only showed impaired T cell reconstitution and thymus regeneration after allogeneic bone marrow nucleated cell transplantation but also exhibited improved capacity to graft both leukemic and solid tumor cells compared with NSI, NOG, and NDG mice. Moreover, the NSIN mice facilitated the monitoring and in vivo imaging of both leukemia and solid tumors. Therefore, our NSIN mice provide a new platform for xenograft mouse models in basic and translational research.

Cancer Immunotherapy: Historical Perspective of a Clinical Revolution and Emerging Preclinical Animal Models

At the turn of the last century, the emerging field of medical oncology chose a cytotoxic approach to cancer therapy over an immune-centered approach at a time when evidence in support of either paradigm did not yet exist. Today, nearly 120 years of data have established that (a) even the best cytotoxic regimens only infrequently cure late-stage malignancy and (b) strategies that supplement and augment existing antitumor immune responses offer the greatest opportunities to potentiate durable remission in cancer. Despite widespread acceptance of these paradigms today, the ability of the immune system to recognize and fight cancer was a highly controversial topic for much of the twentieth century. Why this modern paradigmatic mainstay should have been both dubious and controversial for such an extended period is a topic of considerable interest that merits candid discussion. Herein, we review the literature to identify and describe the watershed events that ultimately led to the acceptance of immunotherapy as a viable regimen for the treatment of neoplastic malignancy. In addition to noting important clinical discoveries, we also focus on research milestones and the development of critical model systems in rodents and dogs including the advanced modeling techniques that allowed development of patient-derived xenografts. Together, their use will further our understanding of cancer biology and tumor immunology, allow for a speedier assessment of the efficacy and safety of novel approaches, and ultimately provide a faster bench to beside transition.

Orthotopic Patient-Derived Pancreatic Cancer Xenografts Engraft Into the Pancreatic Parenchyma, Metastasize, and Induce Muscle Wasting to Recapitulate the Human Disease

OBJECTIVE

Limitations associated with current animal models serve as a major obstacle to reliable preclinical evaluation of therapies in pancreatic cancer (PC). In an effort to develop more reliable preclinical models, we have recently established a subcutaneous patient-derived xenograft (PDX) model. However, critical aspects of PC responsible for its highly lethal nature, such as the development of distant metastasis and cancer cachexia, remain underrepresented in the flank PDX model. The purpose of this study was to evaluate the degree to which an orthotopic PDX model of PC recapitulates these aspects of the human disease.

METHODS

Human PDX-derived PC tumors were implanted directly into the pancreas of NOD.Cg-Prkdc Il2rg/SzJ mice. Tumor growth, metastasis, and muscle wasting were then evaluated.

RESULTS

Orthotopically implanted PDX-derived tumors consistently incorporated into the murine pancreatic parenchyma, metastasized to both the liver and lungs and induced muscle wasting directly proportional to the size of the tumor, consistent of the cancer cachexia syndrome.

CONCLUSIONS

Through the orthotopic implantation technique described, we demonstrate a highly reproducible model that recapitulates both local and systemic aspects of human PC.

Loss of calponin h1 confers anoikis resistance and tumor progression in the development of high-grade serous carcinoma originating from the fallopian tube epithelium

Increasing evidence indicates that ovarian high-grade serous carcinoma (HGSC) originates from the fallopian tube epithelium and metastasizes to the ovary as the secondary site. A working hypothesis is that detached tubal HGSC cells survive anoikis and implant on the ovary. In this study, we found that downregulation of calponin h1 (CNN1) is necessary for the anoikis survival and cell transformation. CNN1 was progressively downregulated in cells and tissues representing different stages of HGSC development from fallopian tube epithelium (FTE). Knock down of CNN1 in immortalized human FTE cells conferred gains of resistance to anoikis and transformation phenotypes including anchorage independent growth (AIG) and xenograft tumorigenesis in NSG mice. Conversely, overexpression of CNN1 in RAS-transformed FTE cells resulted in an almost complete loss of AIG and tumorigenesis. Besides, there was a dramatic change of cell morphology from a polygonal, raised appearance to a round and flattened one. Increase in cell adhesion to laminin and collagen, and reduction in cell motility, anoikis resistance and invasiveness were also observed. A microarray analysis revealed upregulation of genes involved in cytoskeleton stabilization and signal transduction, and downregulation of genes involved in cytokine and chemokine activities. The study disclosed multiple tumor suppressor roles of CNN1 in the development of HGSC from the fallopian tube, and loss of CNN1 expression is crucial for its metastasis to a new site.

Current status and perspectives of patient-derived xenograft models in cancer research

Cancers remain a major public health problem worldwide, which still require profound research in both the basic and preclinical fields. Patient-derived xenograft (PDX) models are created when cancerous cells or tissues from patients' primary tumors are implanted into immunodeficient mice to simulate human tumor biology in vivo, which have been extensively used in cancer research. The routes of implantation appeared to affect the outcome of PDX research, and there has been increasing applications of patient-derived orthotopic xenograft (PDOX) models. In this review, we firstly summarize the methodology to establish PDX models and then go over recent application and function of PDX models in basic cancer research on the areas of cancer characterization, initiation, proliferation, metastasis, and tumor microenvironment and in preclinical explorations of anti-cancer targets, drugs, and therapeutic strategies and finally give our perspectives on the future prospects of PDX models.

The simultaneous inhibition of the mTOR and MAPK pathways with Gnetin-C induces apoptosis in acute myeloid leukemia

Acute myelogenous leukemia (AML) is a clinically heterogeneous disease that is frequently associated with relapse and a poor prognosis. Among the various subtypes, AML with the monosomal karyotype (AML-MK) has an extremely unfavorable prognosis. We performed screening to identify antitumor compounds that are capable of inducing apoptosis in primary leukemia cells harboring the AML-MK karyotype and identified a naturally occurring stilbene, Gnetin-C, with potent anti-tumor activities against AML cells from patients with various cytogenetic abnormalities, including patients with the AML-MK karyotype. Gnetin-C simultaneously inhibits the ERK1/2 and the AKT/mTOR pathways, two signals that are essential for the survival of leukemia cells. A combination of Gnetin-C with low doses of chemotherapeutic drugs led to synergistic anti-tumor effects against AML cells. In an immunodeficient mouse model of human leukemia, Gnetin-C attenuated the formation of leukemia, depleted leukemia cells and improved survival. These findings suggest that Gnetin-C has antitumor activities in AML and supports the therapeutic potential of blocking two different pathways in AML.

A novel hemolytic complement-sufficient NSG mouse model supports studies of complement-mediated antitumor activity in vivo

Monoclonal antibodies (mAbs) have emerged as a mainstream therapeutic option against cancer. mAbs mediate tumor cell-killing through several mechanisms including complement-dependent cytotoxicity (CDC). However, studies of mAb-mediated CDC against tumor cells remain largely dependent on in vitro systems. Previously developed and widely used NOD-scid IL2rγ^null (NSG) mice support enhanced engraftment of many primary human tumors. However, NSG mice have a 2-bp deletion in the coding region of the hemolytic complement (Hc) gene, and it is not possible to evaluate CDC activity in NSG mice. To address this limitation, we generated a novel strain of NSG mice-NSG-Hc¹-that have an intact complement system able to generate the membrane attack complex. Utilizing the Daudi Burkitt's human lymphoma cell line, and the anti-human CD20 mAb rituximab, we further demonstrated that the complement system in NSG-Hc¹ mice is fully functional. NSG-Hc¹ mice expressed CDC activity against Daudi cells in vivo following rituximab treatment and showed longer overall survival compared with rituximab-treated NSG mice that lack hemolytic complement. Our results validate the NSG-Hc¹ mouse model as a platform for testing mechanisms underlying CDC in vivo and suggest its potential use to compare complement-dependent and complement-independent cytotoxic activity mediated by therapeutic mAbs.

Host antitumor resistance improved by the macrophage polarization in a chimera model of patients with HCC

Despite major advances in curative and palliative approaches, hepatocellular carcinoma (HCC) is still the third leading cause of cancer-related death worldwide. M1 macrophages (Mϕ) play a key role in host antitumor defenses in HCC. In our study, CD14⁺ cells were isolated from the peripheral blood of four groups of HCC patients (group-1, patients with stage 0 HCC; group-2, patients with stage A HCC; group-3, patients with stage B HCC; and group-4, patients with stage C HCC) and characterized phenotypically. Then, CD14⁺ cells from group-2 and group-3 HCC patients were induced to polarize and tested for their antitumor abilities in a chimera model of HCC patients. Human HCCs (HepG2 solid tumors) grew in a chimera model of group-3 patients (group-3 HCC chimeras) but not in a chimera model of group-2 patients (group-2 HCC chimeras). In response to HCC antigens, the majority of CD14⁺ cells from group-2 patients (group-2 CD14⁺ cells) switched to the M1 phenotype (IL-12⁺IL-10^-iNOS⁺cells), whereas the majority of CD14⁺ cells from group-3 patients (group-3 CD14⁺ cells) did not switch to the M1 phenotype and continued to express M2b phenotypic properties (IL-12^-IL-10⁺CCL1⁺iNOS^-cells). Group-3 CD14⁺ cells showed M1Mϕ polarization after treatment with CCL1 antisense oligodeoxynucleotide (ODN). Therefore, our study indicates that anti-HCC defenses of group-3 HCC chimeras are improved after CCL1 antisense ODN treatment.

Experimental animal modeling for immuno-oncology

Immuno-oncology (I/O) research has intensified significantly in recent years due to the breakthrough development and the regulatory approval of several immune checkpoint inhibitors, leading to the rapid expansion of the new discovery of novel I/O therapies, new checkpoint inhibitors and beyond. However, many I/O questions remain unanswered, including why only certain subsets of patients respond to these treatments, who the responders would be, and how to expand patient response (the conversion of non-responders or maximizing response in partial responders). All of these require relevant I/O experimental systems, particularly relevant preclinical animal models. Compared to other oncology drug discovery, e.g. cytotoxic and targeted drugs, a lack of relevant animal models is a major obstacle in I/O drug discovery, and an urgent and unmet need. Despite the obvious importance, and the fact that much I/O research has been performed using many different animal models, there are few comprehensive and introductory reviews on this topic. This article attempts to review the efforts in development of a variety of such models, as well as their applications and limitations for readers new to the field, particularly those in the pharmaceutical industry.

5-Amino-3-methyl-4-isoxazolecarboxylic acid hydrazide derivatives with in vitro immunomodulatory activities

Isoxazoles are an important class of compounds of potential therapeutic value. The aim of this study was to determine immunotropic effects of 5-amino-3-methyl-4-isoxazolecarboxylic acid hydrazide derivatives on spontaneous and mitogen-induced lymphocyte proliferation in young and old mice, cytokine production by peritoneal cells as well as possible mechanism of action in a model of Jurkat cells. Three-month-old and 13-month-old BALB/c mice were used as donors of the cells from a thymus, a spleen, mesenteric lymph nodes, and a peritoneal cavity. Spontaneous and concanavalin A or lipopolysaccharide (LPS)-induced cell proliferation was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric method. IL-1β and TNF-α production induced by LPS in macrophage-enriched peritoneal cell cultures was measured by enzyme-linked immunoassay. 5-amino-3-methyl-4-isoxazolecarboxylic acid hydrazide, 01K (4-phenyl-1-(5-amino-3-methylisoxazole-4-carbonyl)-thiosemicarbazide), and 06K (4-(4-chlorophenyl)-1-(5-amino-3-methylisoxazole-4-carbonyl)-thiosemicarbazide) exhibited regulatory activity in the proliferation tests. Prevailing stimulatory activity of the hydrazide and inhibitory activity of 01K and 06K was observed. Those effects were connected with different influence of the compounds on signaling proteins expression in Jurkat cells. The regulatory effects of the compounds on IL-1β production were more profound than those on TNF-α. Differences in the compound activity in young versus old mice were mainly restricted to 01K. Immunosuppressive isoxazole leflunomide and a stimulatory RM-11 (1,7-dimethyl-8-oxo-1,2H-isoxazole [5,4-e]triazepine) were applied as reference drugs.

NSG Mice Provide a Better Spontaneous Model of Breast Cancer Metastasis than Athymic (Nude) Mice

Metastasis is the most common cause of mortality in breast cancer patients worldwide. To identify improved mouse models for breast cancer growth and spontaneous metastasis, we examined growth and metastasis of both estrogen receptor positive (T47D) and negative (MDA-MB-231, SUM1315, and CN34BrM) human breast cancer cells in nude and NSG mice. Both primary tumor growth and spontaneous metastases were increased in NSG mice compared to nude mice. In addition, a pattern of metastasis similar to that observed in human breast cancer patients (metastases to the lungs, liver, bones, brain, and lymph nodes) was found in NSG mice. Furthermore, there was an increase in the metastatic burden in NSG compared to nude mice that were injected with MDA-MB-231 breast cancer cells in an intracardiac experimental metastasis model. This data demonstrates that NSG mice provide a better model for studying human breast cancer metastasis compared to the current nude mouse model.

AC220 and AraC cause differential inhibitory dynamics in patient-derived M5-AML with FLT3-ITD and, thus, ultimately distinct therapeutic outcomes

Engrafting the bone marrow cells of a patient with M5 acute myeloid leukemia into immunocompromised mice (AM7577) resulted in serially transferrable stable AML and eventual mortality. The disease starts in the bone marrow and then expands to peripheral areas, which is typical of M5 leukemogenesis, where high leukemic burden in blood is coincident with symptoms/mortality. The leukemic cells in the mice had myeloid morphology, phenotypes, and genotypes (including the internal tandem duplication of FMS-like tyrosine kinase receptor 3 gene [FLT3-ITD]) similar to those of the original patient. Autocrine mechanisms of human granulocyte-macrophage colony-stimulating factor/interleukin-3 likely support AM7577 growth in mice. Treatment with FLT3 TKI (AC220) caused complete remission in peripheral blood, spleen, and bone, along with relief of symptoms and extended life, hinting that FLT3-ITD may be a key leukemogenic driver maintaining the disease. Interestingly, withdrawal of AC220 (high dose) did not result in relapse of disease, suggesting cure. These results, however, are in contrast to cytarabine (AraC) induction treatment: First, although AraC significantly suppresses the diseases in blood, and to a lesser degree in bone marrow and spleen, the suppression is temporary and does not prevent eventual onset of disease/death. Second, the withdrawal of AraC always resulted in rapid relapse in peripheral blood and eventually death. Our observation in this patient-derived model may provide useful information for clinical applications of the two drugs.