B-Cell Lymphoma Patient-Derived Xenograft Models Enable Drug Discovery and Are a Platform for Personalized Therapy

Experimental model of primary intraocular lymphoma based on BALB/CaNn strain and A20 cells is optimal for investigational research

AIM

The purpose of this project was to compare the characteristics of two experimental murine models of primary intraocular lymphoma (PIOL) and determine which experimental model is most suitable for further investigational research to elucidate the pathophysiology of PIOL and to find new therapeutical strategies.

METHODS

In both experimental models PIOL was induced in immunocompetent mice with intravitreal injection of syngeneic B-cell lymphoma cell lines. Murine strain C3H/HeN and cell line 38C13 were used in the first model and BALB/CaNn mice and cell line A20 in the second model. During the experiments, thorough clinical evaluation (using photo documentation, ultrasonography, and MRI) and histological evaluation were performed.

RESULTS

In both models, the percentage of PIOL development was high, reaching nearly 80%. Disease progression was faster in C3H/HeN with exophthalmos occurring on average on day 10. Vitreous involvement was a predominant sign in the clinical presentation of this group. In BALB/CaNn mice exophthalmos occurred on average on day 22. The predominant clinical sign in the BALB/CaNn group was tumorous infiltration of the retina, optic disc, and tumorous retinal detachment.

CONCLUSION

Slower progression of the disease in BALB/CaNn mice, greater possibility to examine the retina due to mild vitreous involvement, and later occurrence of exophthalmos makes this strain more suitable for further investigational research.

Antitumor efficacy of a sequence-specific DNA-targeted γPNA-based c-Myc inhibitor

Targeting oncogenes at the genomic DNA level can open new avenues for precision medicine. Significant efforts are ongoing to target oncogenes using RNA-targeted and protein-targeted platforms, but no progress has been made to target genomic DNA for cancer therapy. Here, we introduce a gamma peptide nucleic acid (γPNA)-based genomic DNA-targeted platform to silence oncogenes in vivo. γPNAs efficiently invade the mixed sequences of genomic DNA with high affinity and specificity. As a proof of concept, we establish that γPNA can inhibit c-Myc transcription in multiple cell lines. We evaluate the in vivo efficacy and safety of genomic DNA targeting in three pre-clinical models. We also establish that anti-transcription γPNA in combination with histone deacetylase inhibitors and chemotherapeutic drugs results in robust antitumor activity in cell-line- and patient-derived xenografts. Overall, this strategy offers a unique therapeutic platform to target genomic DNA to inhibit oncogenes for cancer therapy.

Mouse models of diffuse large B cell lymphoma

Diffuse large B cell lymphoma (DLBCL) is a genetically highly heterogeneous disease. Yet, to date, the vast majority of patients receive standardized frontline chemo-immune-therapy consisting of an anthracycline backbone. Using these regimens, approximately 65% of patients can be cured, whereas the remaining 35% of patients will face relapsed or refractory disease, which, even in the era of CAR-T cells, is difficult to treat. To systematically tackle this high medical need, it is important to design, generate and deploy suitable in vivo model systems that capture disease biology, heterogeneity and drug response. Recently published, large comprehensive genomic characterization studies, which defined molecular sub-groups of DLBCL, provide an ideal framework for the generation of autochthonous mouse models, as well as an ideal benchmark for cell line-derived or patient-derived mouse models of DLBCL. Here we discuss the current state of the art in the field of mouse modelling of human DLBCL, with a particular focus on disease biology and genetically defined molecular vulnerabilities, as well as potential targeting strategies.

Modeling the crosstalk between malignant B cells and their microenvironment in B-cell lymphomas: challenges and opportunities

B-cell lymphomas are a group of heterogeneous neoplasms resulting from the clonal expansion of mature B cells arrested at various stages of differentiation. Specifically, two lymphoma subtypes arise from germinal centers (GCs), namely follicular lymphoma (FL) and GC B-cell diffuse large B-cell lymphoma (GCB-DLBCL). In addition to recent advances in describing the genetic landscape of FL and GCB-DLBCL, tumor microenvironment (TME) has progressively emerged as a central determinant of early lymphomagenesis, subclonal evolution, and late progression/transformation. The lymphoma-supportive niche integrates a dynamic and coordinated network of immune and stromal cells defining microarchitecture and mechanical constraints and regulating tumor cell migration, survival, proliferation, and immune escape. Several questions are still unsolved regarding the interplay between lymphoma B cells and their TME, including the mechanisms supporting these bidirectional interactions, the impact of the kinetic and spatial heterogeneity of the tumor niche on B-cell heterogeneity, and how individual genetic alterations can trigger both B-cell intrinsic and B-cell extrinsic signals driving the reprogramming of non-malignant cells. Finally, it is not clear whether these interactions might promote resistance to treatment or, conversely, offer valuable therapeutic opportunities. A major challenge in addressing these questions is the lack of relevant models integrating tumor cells with specific genetic hits, non-malignant cells with adequate functional properties and organization, extracellular matrix, and biomechanical forces. We propose here an overview of the 3D in vitro models, xenograft approaches, and genetically-engineered mouse models recently developed to study GC B-cell lymphomas with a specific focus on the pros and cons of each strategy in understanding B-cell lymphomagenesis and evaluating new therapeutic strategies.

Peripheral helper-T-cell-derived CXCL13 is a crucial pathogenic factor in idiopathic multicentric Castleman disease

Castleman disease (CD) is a rare lymphoproliferative disorder. Among subtypes of CD, idiopathic multicentric CD-not otherwise specified (iMCD-NOS) has a poor prognosis and its pathogenesis is largely unknown. Here we present a xenotransplantation model of iMCD-NOS pathogenesis. Immunodeficient mice, transplanted with lymph node (LN) cells from iMCD-NOS patients, develop iMCD-like lethal inflammation, while mice transplanted with LN cells from non-iMCD patients without inflammation serve as negative control. Grafts depleted of human CD3+ T cells fail to induce inflammation in vivo. Upon engraftment, peripheral helper T (Tph) cells expand and levels of human CXCL13 substantially increase in the sera of mice. A neutralizing antibody against human CXCL13 blocks development of inflammation and improves survival in the recipient mice. Our study thus indicates that Tph cells, producing CXCL13 play a critical role in the pathogenesis of iMCD-NOS, and establishes iMCD-NOS as an immunoregulatory disorder.

Beyond Bruton's tyrosine kinase inhibitors in mantle cell lymphoma: bispecific antibodies, antibody-drug conjugates, CAR T-cells, and novel agents

Mantle cell lymphoma is a B cell non-Hodgkin lymphoma (NHL), representing 2-6% of all NHLs and characterized by overexpression of cyclin D1. The last decade has seen the development of many novel treatment approaches in MCL, most notably the class of Bruton's tyrosine kinase inhibitors (BTKi). BTKi has shown excellent outcomes for patients with relapsed or refractory MCL and is now being studied in the first-line setting. However, patients eventually progress on BTKi due to the development of resistance. Additionally, there is an alteration in the tumor microenvironment in these patients with varying biological and therapeutic implications. Hence, it is necessary to explore novel therapeutic strategies that can be effective in those who progressed on BTKi or potentially circumvent resistance. In this review, we provide a brief overview of BTKi, then discuss the various mechanisms of BTK resistance including the role of genetic alteration, cancer stem cells, tumor microenvironment, and adaptive reprogramming bypassing the effect of BTK inhibition, and then provide a comprehensive review of current and emerging therapeutic options beyond BTKi including novel agents, CAR T cells, bispecific antibodies, and antibody-drug conjugates.

Progress in construction of mouse models to investigate the pathogenesis and immune therapy of human hematological malignancy

Hematological malignancy is a disease arisen by complicate reasons that seriously endangers human health. The research on its pathogenesis and therapies depends on the usage of animal models. Conventional animal model cannot faithfully mirror some characteristics of human features due to the evolutionary divergence, whereas the mouse models hosting human hematological malignancy are more and more applied in basic as well as translational investigations in recent years. According to the construction methods, they can be divided into different types (e.g. cell-derived xenograft (CDX) and patient-derived xenograft model (PDX) model) that have diverse characteristics and application values. In addition, a variety of strategies have been developed to improve human hematological malignant cell engraftment and differentiation in vivo. Moreover, the humanized mouse model with both functional human immune system and autologous human hematological malignancy provides a unique tool for the evaluation of the efficacy of novel immunotherapeutic drugs/approaches. Herein, we first review the evolution of the mouse model of human hematological malignancy; Then, we analyze the characteristics of different types of models and summarize the ways to improve the models; Finally, the way and value of humanized mouse model of human immune system in the immunotherapy of human hematological malignancy are discussed.

Endemic Burkitt lymphoma avatar mouse models for exploring inter-patient tumor variation and testing targeted therapies

Endemic Burkitt lymphoma (BL) is a childhood cancer in sub-Saharan Africa characterized by Epstein-Barr virus and malaria-associated aberrant B-cell activation and MYC chromosomal translocation. Survival rates hover at 50% after conventional chemotherapies; therefore, clinically relevant models are necessary to test additional therapies. Hence, we established five patient-derived BL tumor cell lines and corresponding NSG-BL avatar mouse models. Transcriptomics confirmed that our BL lines maintained fidelity from patient tumors to NSG-BL tumors. However, we found significant variation in tumor growth and survival among NSG-BL avatars and in Epstein-Barr virus protein expression patterns. We tested rituximab responsiveness and found one NSG-BL model exhibiting direct sensitivity, characterized by apoptotic gene expression counterbalanced by unfolded protein response and mTOR pro-survival pathways. In rituximab-unresponsive tumors, we observed an IFN-α signature confirmed by the expression of IRF7 and ISG15. Our results demonstrate significant inter-patient tumor variation and heterogeneity, and that contemporary patient-derived BL cell lines and NSG-BL avatars are feasible tools to guide new therapeutic strategies and improve outcomes for these children.

Patient-derived xenograft models in cancer therapy: technologies and applications

Patient-derived xenograft (PDX) models, in which tumor tissues from patients are implanted into immunocompromised or humanized mice, have shown superiority in recapitulating the characteristics of cancer, such as the spatial structure of cancer and the intratumor heterogeneity of cancer. Moreover, PDX models retain the genomic features of patients across different stages, subtypes, and diversified treatment backgrounds. Optimized PDX engraftment procedures and modern technologies such as multi-omics and deep learning have enabled a more comprehensive depiction of the PDX molecular landscape and boosted the utilization of PDX models. These irreplaceable advantages make PDX models an ideal choice in cancer treatment studies, such as preclinical trials of novel drugs, validating novel drug combinations, screening drug-sensitive patients, and exploring drug resistance mechanisms. In this review, we gave an overview of the history of PDX models and the process of PDX model establishment. Subsequently, the review presents the strengths and weaknesses of PDX models and highlights the integration of novel technologies in PDX model research. Finally, we delineated the broad application of PDX models in chemotherapy, targeted therapy, immunotherapy, and other novel therapies.

A novel patient-derived 3D model recapitulates mantle cell lymphoma lymph node signaling, immune profile and in vivo ibrutinib responses

Mantle cell lymphoma (MCL), a rare and aggressive B-cell non-Hodgkin lymphoma, mainly develops in the lymph node (LN) and creates a protective and immunosuppressive niche that facilitates tumor survival, proliferation and chemoresistance. To capture disease heterogeneity and tumor microenvironment (TME) cues, we have developed the first patient-derived MCL spheroids (MCL-PDLS) that recapitulate tumor oncogenic pathways and immune microenvironment in a multiplexed system that allows easy drug screening, including immunotherapies. MCL spheroids, integrated by tumor B cells, monocytes and autologous T-cells self-organize in disc-shaped structures, where B and T-cells maintain viability and proliferate, and monocytes differentiate into M2-like macrophages. RNA-seq analysis demonstrated that tumor cells recapitulate hallmarks of MCL-LN (proliferation, NF-kB and BCR), with T cells exhibiting an exhaustion profile (PD1, TIM-3 and TIGIT). MCL-PDLS reproduces in vivo responses to ibrutinib and demonstrates that combination of ibrutinib with nivolumab (anti-PD1) may be effective in ibrutinib-resistant cases by engaging an immune response with increased interferon gamma and granzyme B release. In conclusion, MCL-PDLS recapitulates specific MCL-LN features and in vivo responses to ibrutinib, representing a robust tool to study MCL interaction with the immune TME and to perform drug screening in a patient-derived system, advancing toward personalized therapeutic approaches.

Targeting CD47 enhanced the antitumor immunity of PD-L1 blockade in B-cell lymphoma

Background: Only a subset of B-cell lymphoma (BCL) patients can benefit from immune checkpoint inhibitors targeting PD-1/PD-L1. Materials & methods: In the A20 model, SIRPα-Fc and anti-PD-L1 were employed to target CD47 and PD-L1 simultaneously. Flow cytometry, immunofluorescence and quantitative polymerase chain reaction were used to unravel the potential mechanisms. Results: Simultaneously targeting CD47 and PD-L1 activated CD8⁺ T cells with an increased release of effector molecules. Furthermore, infiltration of F4/80⁺iNOS⁺ M1 macrophages was enhanced by the dual therapy. Conclusion: Anti-CD47 therapy could sensitize BCL tumors to anti-PD-L1 therapy in a CD8⁺ T-cell- and M1-macrophage-dependent manner by promoting cytotoxic lymphocyte infiltration, which may provide a potential strategy for BCL treatment by simultaneously targeting CD47 and PD-L1.

Complex genetic and histopathological study of 15 patient-derived xenografts of aggressive lymphomas

Non-Hodgkin lymphomas (NHL) represent the most common hematologic malignancies. Patient-derived xenografts (PDXs) are used for various aspects of translational research including preclinical in vivo validation of experimental treatment approaches. While it was repeatedly demonstrated that PDXs keep majority of somatic mutations with the primary lymphoma samples, from which they were derived, the composition of PDX tumor microenvironment (TME) has not been extensively studied. We carried out a comparative genetic and histopathological study of 15 PDX models derived from patients with various types of NHL including diffuse large B-cell lymphoma (DLBCL; n = 7), Burkitt lymphoma (BL; n = 1), mantle cell lymphoma (MCL; n = 2), and peripheral T-cell lymphomas (PTCL; n = 5). Whole exome sequencing (WES) of the PDXs and primary lymphoma cells was implemented in 13 out of 15 cases with available DNA samples. Standard immunohistochemistry (IHC) was used to analyze the composition of PDX TME. WES data confirmed that PDXs maintained the genetic heterogeneity with the original primary lymphoma cells. In contrast, IHC analysis revealed the following recurrently observed alterations in the composition of PDX tumors: more blastoid lymphoma cell morphology, increased proliferation rate, lack of non-malignant cellular components including T cells and (human or murine) macrophages, and significantly lower intratumoral microvessel density and microvessel area composed of murine vessels. In addition, PDX tumors derived from T-NHL displayed additional differences compared to the primary lymphoma samples including markedly lower desmoplasia (i.e., the extent of both reticular and collagen fibrosis), loss of expression of cytotoxic granules (i.e., perforin, TIA, granzyme B), or loss of expression of T-cell specific antigens (i.e., CD3, CD4, CD8). Our data suggest that despite keeping the same genetic profiles, PDX models of aggressive NHL do not recapitulate the microenvironmental heterogeneity of the original lymphomas. These findings have implications on the relevance of PDX models in the context of preclinical research.

Long-term Follow-up of Patients with Relapsed or Refractory Non-Hodgkin Lymphoma Treated with Venetoclax in a Phase I, First-in-Human Study

PURPOSE

We previously reported a 44% overall response rate (ORR) with the oral BCL-2 inhibitor venetoclax in a phase I study of relapsed/refractory non-Hodgkin lymphoma (NHL). Complete response (CR) was observed in patients with mantle cell lymphoma [(MCL), 21%, n = 6/28] and follicular lymphoma [(FL), 17%, n = 5/29], and partial response (PR) noted in several patients with Waldenström macroglobulinemia (WM), and marginal zone lymphoma (MZL). Here, we report the long-term outcomes of these four cohorts.

PATIENTS AND METHODS

All patients (n = 106) received venetoclax monotherapy in dose cohorts of 200 to 1,200 mg daily until disease progression or unacceptable toxicity. ORR, progression-free survival (PFS), duration of response (DoR), and adverse events (AEs) were evaluated.

RESULTS

At a median follow-up of 38.5 months (range, 30.0-46.5), the median PFS for all 106 patients was 5.4 [95% confidence interval (CI), 3.5-8.4] months (FL, 10.8; MCL, 11.3; MZL, 21.2; and WM, 30.4). The median DoR was 14.9 (95% CI, 9.7-27.6) months (FL, 26.6; MCL, 15.7; MZL, 20.1; and WM, 25.3). Achievement of CR versus PR predicted longer DoR in both MCL (31.5 vs. 10.1 months) and FL (37.6 vs. 9.7 months). All grade hematologic AEs were infrequent: neutropenia (19%), anemia (19%), and thrombocytopenia (17%), with no new cytopenias after 2 years on therapy. Nonhematologic AEs included nausea (49%), diarrhea (46%), fatigue (44%), with decreased incidence after 1 year.

CONCLUSIONS

Venetoclax monotherapy has a manageable safety profile and achieves durable responses in a subset of patients with FL, MCL, WM, and MZL, particularly in those who achieve CR. Further research is warranted on combination strategies to enhance the durability of response to venetoclax.

Mouse Models of Germinal Center Derived B-Cell Lymphomas

Over the last decades, the revolution in DNA sequencing has changed the way we understand the genetics and biology of B-cell lymphomas by uncovering a large number of recurrently mutated genes, whose aberrant function is likely to play an important role in the initiation and/or maintenance of these cancers. Dissecting how the involved genes contribute to the physiology and pathology of germinal center (GC) B cells -the origin of most B-cell lymphomas- will be key to advance our ability to diagnose and treat these patients. Genetically engineered mouse models (GEMM) that faithfully recapitulate lymphoma-associated genetic alterations offer a valuable platform to investigate the pathogenic roles of candidate oncogenes and tumor suppressors in vivo, and to pre-clinically develop new therapeutic principles in the context of an intact tumor immune microenvironment. In this review, we provide a summary of state-of-the art GEMMs obtained by accurately modelling the most common genetic alterations found in human GC B cell malignancies, with a focus on Burkitt lymphoma, follicular lymphoma, and diffuse large B-cell lymphoma, and we discuss how lessons learned from these models can help guide the design of novel therapeutic approaches for this disease.

In Vivo and Ex Vivo Patient-Derived Tumor Xenograft Models of Lymphoma for Drug Discovery

In the hemato-oncology field, remarkable scientific progress has been achieved, primarily propelled by the discovery of new technologies, improvement in genomics, and novel in vitro and in vivo models. The establishment of multiple cell line collections and the development of instrumental mouse models enhanced our ability to discover effective therapeutics. However, cancer models that faithfully mimic individual cancers are still imperfect. Patient-derived tumor xenografts (PDTXs) have emerged as a powerful tool for identifying the mechanisms which drive tumorigenesis and for testing potential therapeutic interventions. The recognition that PDTXs can maintain many of the donor samples' properties enabled the development of new strategies for discovering and implementing therapies. Described in this article are protocols for the generation and characterization of lymphoma PDTXs that may be used as the basis of shared procedures. Universal protocols will foster the model utilization, enable the integration of public and private repositories, and aid in the development of shared platforms. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Tissue handling and cryopreservation of primary and PDTX samples Basic Protocol 2: Performing tumor implant in immunocompromised mice PDTX models Alternate Protocol 1: Intra-medullary femoral injection Alternate Protocol 2: Intravenous injection Alternate Protocol 3: Intraperitoneal injection Support Protocol 1: Phenotypical characterization of PDTXs by flow cytometry Support Protocol 2: Biological and molecular characterization of PDTX tumors by PCR detection of IGK, IGH, and TCR rearrangements Basic Protocol 3: Harvesting PDTX-derived tumor cells for ex vivo experiments Basic Protocol 4: In vivo testing of multiple compounds in a PDTX mouse model.

An Overview on Diffuse Large B-Cell Lymphoma Models: Towards a Functional Genomics Approach

Simple Summary

Lymphoma research is a paradigm of integrating basic and applied research within the fields of molecular marker-based diagnosis and therapy. In recent years, major advances in next-generation sequencing have substantially improved the understanding of the genomics underlying diffuse large B-cell lymphoma (DLBCL), the most frequent type of B-cell lymphoma. This review addresses the various approaches that have helped unveil the biology and intricate alterations in this pathology, from cell lines to more sophisticated last-generation experimental models, such as organoids. We also provide an overview of the most recent findings in the field, their potential relevance for designing targeted therapies and the corresponding applicability to personalized medicine.

Abstract

Lymphoma research is a paradigm of the integration of basic and clinical research within the fields of diagnosis and therapy. Clinical, phenotypic, and genetic data are currently used to predict which patients could benefit from standard treatment. However, alternative therapies for patients at higher risk from refractoriness or relapse are usually empirically proposed, based on trial and error, without considering the genetic complexity of aggressive B-cell lymphomas. This is primarily due to the intricate mosaic of genetic and epigenetic alterations in lymphomas, which are an obstacle to the prediction of which drug will work for any given patient. Matching a patient’s genes to drug sensitivity by directly testing live tissues comprises the “precision medicine” concept. However, in the case of lymphomas, this concept should be expanded beyond genomics, eventually providing better treatment options for patients in need of alternative therapeutic approaches. We provide an overview of the most recent findings in diffuse large B-cell lymphomas genomics, from the classic functional models used to study tumor biology and the response to experimental treatments using cell lines and mouse models, to the most recent approaches with spheroid/organoid models. We also discuss their potential relevance and applicability to daily clinical practice.

Targeting phosphatidylinositol 3 kinase-β and -δ for Bruton tyrosine kinase resistance in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma; 40% of patients relapse after a complete response or are refractory to therapy. To survive, the activated B-cell (ABC) subtype of DLBCL relies upon B-cell receptor signaling, which can be modulated by the activity of Bruton tyrosine kinase (BTK). Targeting BTK with ibrutinib, an inhibitor, provides a therapeutic approach for this subtype of DLBCL. However, non-Hodgkin lymphoma is often resistant to ibrutinib or acquires resistance soon after exposure. We explored how this resistance develops. We generated 3 isogenic ibrutinib-resistant DLBCL cell lines and investigated the deregulated pathways known to be associated with tumorigenic properties. Reduced levels of BTK and enhanced phosphatidylinositol 3-kinase (PI3K)/AKT signaling were hallmarks of these ibrutinib-resistant cells. Upregulation of PI3K-β expression was demonstrated to drive resistance in ibrutinib-resistant cells, and resistance was reversed by the blocking activity of PI3K-β/δ. Treatment with the selective PI3K-β/δ dual inhibitor KA2237 reduced both tumorigenic properties and survival-based PI3K/AKT/mTOR signaling of these ibrutinib-resistant cells. In addition, combining KA2237 with currently available chemotherapeutic agents synergistically inhibited metabolic growth. This study elucidates the compensatory upregulated PI3K/AKT axis that emerges in ibrutinib-resistant cells.

The Eµ-hnRNP K Murine Model of Lymphoma: Novel Insights into the Role of hnRNP K in B-Cell Malignancies

B-cell lymphomas are one of the most biologically and molecularly heterogeneous group of malignancies. The inherent complexity of this cancer subtype necessitates the development of appropriate animal model systems to characterize the disease with the ultimate objective of identifying effective therapies. In this article, we discuss a new driver of B-cell lymphomas - hnRNP K (heterogenous nuclear ribonucleoprotein K)-an RNA-binding protein. We introduce the Eµ-Hnrnpk mouse model, a murine model characterized by hnRNP K overexpression in B cells, which develops B-cell lymphomas with high penetrance. Molecular analysis of the disease developed in this model reveals an upregulation of the c-Myc oncogene via post-transcriptional and translational mechanisms underscoring the impact of non-genomic MYC activation in B-cell lymphomas. Finally, the transplantability of the disease developed in Eµ-Hnrnpk mice makes it a valuable pre-clinical platform for the assessment of novel therapeutics.

Novel Treatments for Mantle Cell Lymphoma: From Targeted Therapies to CAR T Cells

Mantle cell lymphoma is a rare B-cell non-Hodgkin's lymphoma that retains a sobering prognosis despite an extensive research effort. Mantle cell lymphoma remains incurable even with aggressive, and at times toxic, chemoimmunotherapy with early incorporation of autologous stem cell transplantation. Given this, attention has turned to the use of targeted therapies addressing dysregulation of B-cell signaling pathways. Drugs such as immunomodulatory agents, proteasome inhibitors, and Bruton's tyrosine kinase inhibitors have shown success in the relapsed/refractory population, and there is ongoing investigation into the utilization of novel Bruton's tyrosine kinase, B-cell leukemia/lymphoma-2, and spleen tyrosine kinase inhibitors alone or in combination in both the front-line and relapsed settings. Other areas of research in novel immunotherapies include investigations of bispecific T-cell engagers and antibody-drug conjugates. Most recently, chimeric antigen receptor T-cell therapy has been granted US Food and Drug Administration approval as a result of durable remissions even in high-risk patients who have classically done poorly with traditional chemoimmunotherapy. The intent of this article is to review the literature describing these selective therapies and discuss their current and future roles in the treatment of mantle cell lymphoma.

Heat Shock Proteins in Lymphoma Immunotherapy

Immunotherapy harnessing the host immune system for tumor destruction revolutionized oncology research and advanced treatment strategies for lymphoma patients. Lymphoma is a heterogeneous group of cancer, where the central roles in pathogenesis play immune evasion and dysregulation of multiple signaling pathways. Immunotherapy-based approaches such as engineered T cells (CAR T), immune checkpoint modulators and NK cell-based therapies are now in the frontline of lymphoma research. Even though emerging immunotherapies showed promising results in treating lymphoma patients, low efficacy and on-target/off-tumor toxicity are of a major concern. To address that issue it is suggested to look into the emerging role of heat shock proteins. Heat shock proteins (HSPs) showed to be highly expressed in lymphoma cells. HSPs are known for their abilities to modulate immune responses and inhibit apoptosis, which made their successful entry into cancer clinical trials. Here, we explore the role of HSPs in Hodgkin and Non-Hodgkin lymphoma and their involvement in CAR T therapy, checkpoint blockade and NK cell- based therapies. Understanding the role of HSPs in lymphoma pathogenesis and the ways how HSPs may enhance anti-tumor responses, may help in the development of more effective, specific and safe immunotherapy.

Non-Hodgkin Lymphomas: Malignancies Arising from Mature B Cells

Non-Hodgkin lymphomas (NHLs) are a diverse group of entities, both clinically and molecularly. Here, we review the evolution of classification schemes in B-cell lymphoma, noting the now standard WHO classification system that is based on immune cell-of-origin and molecular phenotypes. We review how lymphomas arise throughout the B-cell development process as well as the molecular and clinical features of prominent B-cell lymphomas. We provide an overview of the major progress that has occurred over the past decade in terms of our molecular understanding of these diseases. We discuss treatment options available and focus on a number of the diverse research tools that have been employed to improve our understanding of these diseases. We discuss the problem of heterogeneity in lymphomas and anticipate that the near future will bring significant advances that provide a measurable impact on NHL outcomes.

Paediatric Burkitt lymphoma patient-derived xenografts capture disease characteristics over time and are a model for therapy

Burkitt lymphoma (BL) accounts for almost two-thirds of all B-cell non-Hodgkin lymphoma (B-NHL) in children and adolescents and is characterised by a MYC translocation and rapid cell turnover. Intensive chemotherapeutic regimens have been developed in recent decades, including the lymphomes malins B (LMB) protocol, which have resulted in a survival rate in excess of 90%. Recent clinical trials have focused on immunochemotherapy, with the addition of rituximab to chemotherapeutic backbones, showing encouraging results. Despite these advances, relapse and refractory disease occurs in up to 10% of patients and salvage options for these carry a dismal prognosis. Efforts to better understand the molecular and functional characteristics driving relapse and refractory disease may help improve this prognosis. This study has established a paediatric BL patient-derived xenograft (PDX) resource which captures and maintains tumour heterogeneity, may be used to better characterise tumours and identify cell populations responsible for therapy resistance.

Genetic and Non-Genetic Mechanisms of Resistance to BCR Signaling Inhibitors in B Cell Malignancies

The approval of BTK and PI3K inhibitors (ibrutinib, idelalisib) represents a revolution in the therapy of B cell malignancies such as chronic lymphocytic leukemia (CLL), mantle-cell lymphoma (MCL), diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), or Waldenström's macroglobulinemia (WM). However, these "BCR inhibitors" function by interfering with B cell pathophysiology in a more complex way than anticipated, and resistance develops through multiple mechanisms. In ibrutinib treated patients, the most commonly described resistance-mechanism is a mutation in BTK itself, which prevents the covalent binding of ibrutinib, or a mutation in PLCG2, which acts to bypass the dependency on BTK at the BCR signalosome. However, additional genetic aberrations leading to resistance are being described (such as mutations in the CARD11, CCND1, BIRC3, TRAF2, TRAF3, TNFAIP3, loss of chromosomal region 6q or 8p, a gain of Toll-like receptor (TLR)/MYD88 signaling or gain of 2p chromosomal region). Furthermore, relative resistance to BTK inhibitors can be caused by non-genetic adaptive mechanisms leading to compensatory pro-survival pathway activation. For instance, PI3K/mTOR/Akt, NFkB and MAPK activation, BCL2, MYC, and XPO1 upregulation or PTEN downregulation lead to B cell survival despite BTK inhibition. Resistance could also arise from activating microenvironmental pathways such as chemokine or integrin signaling via CXCR4 or VLA4 upregulation, respectively. Defining these compensatory pro-survival mechanisms can help to develop novel therapeutic combinations of BTK inhibitors with other inhibitors (such as BH3-mimetic venetoclax, XPO1 inhibitor selinexor, mTOR, or MEK inhibitors). The mechanisms of resistance to PI3K inhibitors remain relatively unclear, but some studies point to MAPK signaling upregulation via both genetic and non-genetic changes, which could be co-targeted therapeutically. Alternatively, drugs mimicking the BTK/PI3K inhibition effect can be used to prevent adhesion and/or malignant B cell migration (chemokine and integrin inhibitors) or to block the pro-proliferative T cell signals in the microenvironment (such as IL4/STAT signaling inhibitors). Here we review the genetic and non-genetic mechanisms of resistance and adaptation to the first generation of BTK and PI3K inhibitors (ibrutinib and idelalisib, respectively), and discuss possible combinatorial therapeutic strategies to overcome resistance or to increase clinical efficacy.

A Hyperactive RelA/p65-Hexokinase 2 Signaling Axis Drives Primary Central Nervous System Lymphoma

Primary central nervous system lymphoma (PCNSL) is an isolated type of lymphoma of the central nervous system and has a dismal prognosis despite intensive chemotherapy. Recent genomic analyses have identified highly recurrent mutations of MYD88 and CD79B in immunocompetent PCNSL, whereas LMP1 activation is commonly observed in Epstein-Barr virus (EBV)-positive PCNSL. However, a lack of clinically representative preclinical models has hampered our understanding of the pathogenic mechanisms by which genetic aberrations drive PCNSL disease phenotypes. Here, we establish a panel of 12 orthotopic, patient-derived xenograft (PDX) models from both immunocompetent and EBV-positive PCNSL and secondary CNSL biopsy specimens. PDXs faithfully retained their phenotypic, metabolic, and genetic features, with 100% concordance of MYD88 and CD79B mutations present in PCNSL in immunocompetent patients. These models revealed a convergent functional dependency upon a deregulated RelA/p65-hexokinase 2 signaling axis, codriven by either mutated MYD88/CD79B or LMP1 with Pin1 overactivation in immunocompetent PCNSL and EBV-positive PCNSL, respectively. Notably, distinct molecular alterations used by immunocompetent and EBV-positive PCNSL converged to deregulate RelA/p65 expression and to drive glycolysis, which is critical for intracerebral tumor progression and FDG-PET imaging characteristics. Genetic and pharmacologic inhibition of this key signaling axis potently suppressed PCNSL growth in vitro and in vivo. These patient-derived models offer a platform for predicting clinical chemotherapeutics efficacy and provide critical insights into PCNSL pathogenic mechanisms, accelerating therapeutic discovery for this aggressive disease. SIGNIFICANCE: A set of clinically relevant CNSL xenografts identifies a hyperactive RelA/p65-hexokinase 2 signaling axis as a driver of progression and potential therapeutic target for treatment and provides a foundational preclinical platform. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/23/5330/F1.large.jpg.

Metabolic reprogramming toward oxidative phosphorylation identifies a therapeutic target for mantle cell lymphoma

Metabolic reprogramming is linked to cancer cell growth and proliferation, metastasis, and therapeutic resistance in a multitude of cancers. Targeting dysregulated metabolic pathways to overcome resistance, an urgent clinical need in all relapsed/refractory cancers, remains difficult. Through genomic analyses of clinical specimens, we show that metabolic reprogramming toward oxidative phosphorylation (OXPHOS) and glutaminolysis is associated with therapeutic resistance to the Bruton's tyrosine kinase inhibitor ibrutinib in mantle cell lymphoma (MCL), a B cell lymphoma subtype with poor clinical outcomes. Inhibition of OXPHOS with a clinically applicable small molecule, IACS-010759, which targets complex I of the mitochondrial electron transport chain, results in marked growth inhibition in vitro and in vivo in ibrutinib-resistant patient-derived cancer models. This work suggests that targeting metabolic pathways to subvert therapeutic resistance is a clinically viable approach to treat highly refractory malignancies.

Development and Significance of Mouse Models in Lymphoma Research

PURPOSE OF REVIEW

Animal models have played an indispensable role in interpreting cancer gene functions, pathogenesis of disease, and in the development of innovative therapeutic approaches targeting aberrant biological pathways in human cancers.

RECENT FINDINGS

These models have guided the therapeutic targeting of cancer-causing mutations and paved the way for assessing anti-cancer drug responses and the preclinical development of immunotherapies. The mammalian models of cancer utilize genetically edited or transplanted mice that develop fairly accurate disease histopathology. The mouse model also allows us to study the effect of tumor microenvironment in the development of lymphoma. The emergence of patient-derived xenografts provides a better opportunity for recapitulating primary lymphoma characteristics and researching personalized drug therapy. In conclusion, the refinement and advancement of available mouse models in lymphoma significantly minimize the therapeutic translational failures in patients.

Ibrutinib Resistance Mechanisms and Treatment Strategies for B-Cell lymphomas

Chronic activation of B-cell receptor (BCR) signaling via Bruton tyrosine kinase (BTK) is largely considered to be one of the primary mechanisms driving disease progression in B-Cell lymphomas. Although the BTK-targeting agent ibrutinib has shown promising clinical responses, the presence of primary or acquired resistance is common and often leads to dismal clinical outcomes. Resistance to ibrutinib therapy can be mediated through genetic mutations, up-regulation of alternative survival pathways, or other unknown factors that are not targeted by ibrutinib therapy. Understanding the key determinants, including tumor heterogeneity and rewiring of the molecular networks during disease progression and therapy, will assist exploration of alternative therapeutic strategies. Towards the goal of overcoming ibrutinib resistance, multiple alternative therapeutic agents, including second- and third-generation BTK inhibitors and immunomodulatory drugs, have been discovered and tested in both pre-clinical and clinical settings. Although these agents have shown high response rates alone or in combination with ibrutinib in ibrutinib-treated relapsed/refractory(R/R) lymphoma patients, overall clinical outcomes have not been satisfactory due to drug-associated toxicities and incomplete remission. In this review, we discuss the mechanisms of ibrutinib resistance development in B-cell lymphoma including complexities associated with genomic alterations, non-genetic acquired resistance, cancer stem cells, and the tumor microenvironment. Furthermore, we focus our discussion on more comprehensive views of recent developments in therapeutic strategies to overcome ibrutinib resistance, including novel BTK inhibitors, clinical therapeutic agents, proteolysis-targeting chimeras and immunotherapy regimens.

Novel agents for mantle cell lymphoma: molecular rational and clinical data

INTRODUCTION

Mantle cell lymphoma (MCL) is an aggressive B cell non-Hodgkin lymphoma (NHL) that is characterized by the translocation t(11;14)(q13;q32) and a poor response to rituximab-anthracycline-based chemotherapy. Intensive regimens offer durable response, but a subgroup of MCL patients will not be eligible for those regimens and hence are candidates for less toxic, novel therapies based on a more tailored personalized approach.

AREAS COVERED

This article examines the molecular landscape of MCL, drug resistance mechanisms, and the data on emerging targeted therapies.

EXPERT OPINION

DNA damage pathway, ATM mutation, TP53, and epigenetic abnormalities are key drivers of MCL. sBCL2, PARP, ATR, CDK inhibitors or epigenetic modifiers are among the most promising drugs under investigation in clinical trials. The genomic landscape of MCL suggests two types of disease based on the presence of ATM or TP53 alterations which should be the framework of future molecular driven strategies. Among novel drugs, those interacting with the DNA damage response pathway offer the most effective rational for their use in MCL.

Patient-derived xenograft model engraftment predicts poor prognosis after surgery in patients with pancreatic cancer

OBJECTIVES

To establish and evaluate a first generation patient-derived xenograft (PDX) model in nude mice using tumors resected from pancreatic cancer (PC) patients for the identification of key factors that influence xenograft success and prediction of patient prognosis.

METHODS

Primary tumor samples harvested from PC patients who underwent curative resection between May 2016 and April 2018 at our hospital were xenografted into nude mice. Tumor size was evaluated for 2 months. Patients' baseline characteristics and follow-up data were analyzed.

RESULTS

Tumor xenograft models were generated from 67 patients; 30 (44.8%) were successful and 37 (55.2%) failed. Xenograft models could recapitulate the pathology and genetic information of the primary tumors. Univariate analysis identified tumor engraftment, post-operation CA19-9, tumor size, lymph node status, and lymphovascular invasion as significant predictors (P=0.000, 0.023, 0.004, 0.035 and 0.005, respectively) of disease-free survival (DFS). Multivariate Cox regression analysis confirmed tumor engraftment, tumor size and lymphovascular invasion function as independent risk factors for DFS (P=0.000, 0.039 and 0.025, respectively). The hazard ratio of tumor engraftment for DFS was 0.239 (95% confidence interval, 0.109 to 0.524). Kaplan-Meier analysis of DFS indicated an unfavorable outcome in the engraftment group compared to that in the failed engraftment group (6.2 vs. 12.2 months, log rank P=0.000).

CONCLUSION

The pathology and genetic information of primary PC tumors are recapitulated in the PDX tumor model in nude mice. Furthermore, engraftment success is an effective predictor of disease recurrence in patients after surgery.

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.

Resistance to BTK inhibition by ibrutinib can be overcome by preventing FOXO3a nuclear export and PI3K/AKT activation in B-cell lymphoid malignancies

Chronic activation of the Bruton’s tyrosine kinase (BTK)-mediated B-cell receptor (BCR) signaling is a hallmark of many B-cell lymphoid malignancies, including chronic lymphocytic leukemia (CLL) and diffuse large B-cell lymphoma (DLBCL). Ibrutinib, an FDA approved, orally administered BTK inhibitor, has demonstrated high response rates, however, complete responses are infrequent and acquired resistance to BTK inhibition can emerge. In this study, we generated ibrutinib-resistant (IB-R) cell lines by chronic exposure of CLL and activated B-cell (ABC)-DLBCL cells to ibrutinib in order to investigate the mechanism of acquired resistance to ibrutinib. IB-R cell lines demonstrated downregulation of FOXO3a and PTEN levels and activation of AKT, with their levels being low in the nuclei of resistant cells in comparison to the sensitive counterparts. Inhibition of PI3K and AKT using idelalisib and MK2206, respectively increased ibrutinib-induced apoptosis in IB-R cells by downregulation of pAKT⁴⁷³ and restoring FOXO3a levels, demonstrating the importance of these cell survival factors for ibrutinib-resistance. Notably, the exportin 1 inhibitor, selinexor synergized with ibrutinib in IB-R cells and restored nuclear abundance of FOXO3a and PTEN, suggesting that nuclear accumulation of FOXO3a and PTEN facilitates increase in ibrutinib-induced apoptosis in IB-R cells. These data demonstrate that reactivation of FOXO3a nuclear function enhances the efficacy of ibrutinib and overcomes acquired resistance to ibrutinib. Together, these findings reveal a novel mechanism that confers ibrutinib resistance via aberrant nuclear/cytoplasmic subcellular localization of FOXO3a and could be exploited by rational therapeutic combination regimens for effectively treating lymphoid malignancies.

Therapeutic potential of PI3K signaling in distinct entities of B-cell lymphoma

Introduction: Aberrant phosphatidylinositide 3-kinase (PI3K) signaling drives survival and proliferation of malignant B-cells of different lymphoma entities. Thus, inhibition of PI3K isoforms represents a novel and promising therapeutic approach for the treatment of patients with B-cell lymphomas.Areas covered: Here the authors provide an overview about the PI3K signaling pathway as well as available preclinical and clinical results of different PI3K inhibitors in both indolent and aggressive lymphoma entities.Expert opinion: PI3K inhibitors have shown to be efficacious in different entities of B-cell lymphoma, at this stage particularly in relapsed/refractory settings. However, responses of PI3K inhibitors widely vary among different lymphomas. Additionally, especially infectious and immune-mediated toxicities limit their use at this stage. Thus, the decision to use PI3K inhibitors needs to be balanced between the potential efficacy and associated toxicities as well as the availability of other therapeutic options. Future research might eventually lead to the stratification of patients according to the specific oncogenic addictions of the underlying lymphoma. Additionally, PI3K inhibitors will need to be combined with other therapeutic agents for more specific and effective treatment regimens.

PRMT5 is upregulated by B-cell receptor signaling and forms a positive-feedback loop with PI3K/AKT in lymphoma cells

PRMT5, which regulates gene expression by symmetric dimethylation of histones and non-histone target proteins, is overexpressed and plays a pathogenic role in many cancers. In diffuse large B cell lymphoma (DLBCL), the mechanisms of PRMT5 dysregulation and its role in lymphomagenesis remain largely unknown. Here we demonstrate that B cell receptor (BCR) signaling regulates PRMT5 expression in DLBCL cells. Immunohistochemical analysis reveals elevated levels of PRMT5 expression in DLBCL cases and in germinal center (GC) B cells when compared to naive B cells. PRMT5 can be induced in naive B cells by BCR stimulation. We discovered that BTK-NF-κB signaling induces PRMT5 transcription in activated B cell-like (ABC) DLBCL cells while BCR downstream PI3K-AKT-MYC signaling upregulates PRMT5 expression in both ABC and GCB DLBCL cells. PRMT5 inhibition inhibits the growth of DLBCL cells in vitro and patient derived xenografts. Genomic and biochemical analysis demonstrate that PRMT5 promotes cell cycle progression and activates PI3K-AKT signaling, suggesting a feedback regulatory mechanism to enhance cell survival and proliferation. Co-targeting PRMT5 and AKT by their specific inhibitors is lethal to DLBCL cell lines and primary cancer cells. Therefore, this study provides a mechanistic rationale for clinical trials to evaluate PRMT5 and AKT inhibitors for DLBCL.

Activation of MYC, a bona fide client of HSP90, contributes to intrinsic ibrutinib resistance in mantle cell lymphoma

The BTK inhibitor ibrutinib has demonstrated a remarkable therapeutic effect in mantle cell lymphoma (MCL). However, approximately one-third of patients do not respond to the drug initially. To identify the mechanisms underlying primary ibrutinib resistance in MCL, we analyzed the transcriptome changes in ibrutinib-sensitive and ibrutinib-resistant cell lines on ibrutinib treatment. We found that MYC gene signature was suppressed by ibrutinib in sensitive but not resistant cell lines. We demonstrated that MYC gene was structurally abnormal and MYC protein was overexpressed in MCL cells. Further, MYC knockdown with RNA interference inhibited cell growth in ibrutinib-sensitive as well as ibrutinib-resistant cells. We explored the possibility of inhibiting MYC through HSP90 inhibition. The chaperon protein is overexpressed in both cell lines and primary MCL cells from the patients. We demonstrated that MYC is a bona fide client of HSP90 in the context of MCL by both immunoprecipitation and chemical precipitation. Furthermore, inhibition of HSP90 using PU-H71 induced apoptosis and caused cell cycle arrest. PU-H71 also demonstrates strong and relatively specific inhibition of the MYC transcriptional program compared with other oncogenic pathways. In a MCL patient-derived xenograft model, the HSP90 inhibitor retards tumor growth and prolongs survival. Last, we showed that PU-H71 induced apoptosis and downregulated MYC protein in MCL cells derived from patients who were clinically resistant to ibrutinib. In conclusion, MYC activity underlies intrinsic resistance to ibrutinib in MCL. As a client protein of HSP90, MYC can be inhibited via PU-H71 to overcome primary ibrutinib resistance.

Interrogating B cell signaling pathways: A quest for novel therapies for mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive B cell lymphoma that is largely chemoresistant. Ibrutinib, a drug that inhibits Bruton's tyrosine kinase (BTK), has improved the overall survival of patients with MCL; however, resistance to ibrutinib has emerged as a decisive, negative factor in the prognosis of MCL. Adopting a more patient-centric therapeutic approach that incorporates applied genomics and interrogation of B cell signaling pathways may offer an alternative route to reach durable remission in patients with MCL. Although targeting genetic variants in MCL is not yet feasible in the clinical setting, the identification and targeting of increasingly active B cell signaling pathways may be a viable therapeutic strategy that may improve patient outcomes. Genome-editing tools and sequencing platforms could play dominant roles in patient-centric approaches of treatment in the future, potentially improving clinical outcomes for patients with MCL.

Metabolic Reprogramming of Non-Hodgkin's B-Cell Lymphomas and Potential Therapeutic Strategies

Metabolism is a wide and general term that refers to any intracellular pathways the cell utilizes in order to satisfy its energetic demand and to support cell viability and/or division. Along with phenotypic changes, all mammalian cells including immune cells modulate their metabolic program in order to reach their effector functions. Exacerbated metabolism and metabolic flexibility are also hallmarks of tumor initiation and of tumor cell progression in a complex tumor microenvironment. Metabolic reprogramming is mainly directed by the serine/threonine kinase mTOR (mammalian target of rapamycin). mTOR exists in two structurally and functionally distinct complexes, mTORC1 and mTORC2 that coordinate environmental signals and metabolic/anabolic pathways to provide macromolecules and energy needed for survival and growth. Activation of mTORC1 is required during development, differentiation and activation of immune cells. Aberrant and persistent activation of mTORC1 is often observed in malignant B cells such as Non-Hodgkin's (NH) B-cell lymphomas. Here, we review recent insights on cell metabolism and on basic mechanisms of mTORC1 regulation and metabolic functions. We highlight the distinct mechanisms driving mTORC1 activation in the three most-common types of NH B-cell lymphomas (Diffuse Large B Cell Lymphomas, Follicular Lymphomas, and Mantle Cell Lymphomas), for which the first generation of mTORC1 inhibitors (rapalogs) have been extensively evaluated in preclinical and clinical settings. Finally, we discuss the reasons for limited clinical success of this therapy and focus on potential therapeutic strategies targeting metabolic pathways, upstream and downstream of mTORC1, that can be combined to rapalogs in order to improve patient's outcome.

Primary CNS lymphoma patient-derived orthotopic xenograft model capture the biological and molecular characteristics of the disease

Primary CNS lymphomas (PCNSL) are rare and poor prognosis diffuse large B-cell lymphomas. Because of the brain tumor environment and the restricted distribution of drugs in the CNS, specific PCNSL patient-derived orthotopic xenograft (PDOX) models are needed for preclinical research to improve the prognosis of PCNSL patients. PCNSL patient specimens (n = 6) were grafted in the caudate nucleus of immunodeficient nude mice with a 83% rate of success, while subcutaneous implantation in nude mice of human PCNSL sample did not generate lymphoma, supporting the role of the brain microenvironment in the PCNSL physiopathology. PDOXs showed diffuse infiltration of B-cell lymphoma cells in the brain parenchyma. Each model had a unique mutational signature for genes in the BCR and NF-κB pathways and retained the mutational profile of the primary tumor. The models can be stored as cryopreserved biobank. Human IL-10 levels measured in the plasma of PCNSL-PDOX mice showed to be a reliable tool to monitor the tumor burden. Treatment response could be measured after a short treatment with the targeted therapy ibrutinib. In summary, we established a panel of human PCNSL-PDOX models that capture the histological and molecular characteristics of the disease and that proved suitable for preclinical experiments. Our methods of generation and characterization will enable the generation of additional PDOX-PCNSL models, essential tools for cognitive and preclinical drug discovery.

Dual inhibition of PI3K signaling and histone deacetylation halts proliferation and induces lethality in mantle cell lymphoma

The dysregulation of PI3K signaling has been implicated as an underlying mechanism associated with resistance to Bruton's tyrosine kinase inhibition by ibrutinib in both chronic lymphocytic leukemia and mantle cell lymphoma (MCL). Ibrutinib resistance has become a major unmet clinical need, and the development of therapeutics to overcome ibrutinib resistance will greatly improve the poor outcomes of ibrutinib-exposed MCL patients. CUDC-907 inhibits both PI3K and HDAC functionality to exert synergistic or additive effects. Therefore, the activity of CUDC-907 was examined in MCL cell lines and patient primary cells, including ibrutinib-resistant MCL cells. The efficacy of CUDC-907 was further examined in an ibrutinib-resistant MCL patient-derived xenograft (PDX) mouse model. The molecular mechanisms by which CUDC-907 dually inhibits PI3K and histone deacetylation were assessed using reverse protein array, immunoblotting, and chromatin immunoprecipitation (ChIP) coupled with sequencing. We showed evidence that CUDC-907 treatment increased histone acetylation in MCL cells. We found that CUDC-907 caused decreased proliferation and increased apoptosis in MCL in vitro and in vivo MCL models. In addition, CUDC-907 was effective in inducing lethality in ibrutinib-resistant MCL cells. Lastly, CUDC-907 treatment increased histone acetylation in MCL cells. Overall, these studies suggest that CUDC-907 may be a promising therapeutic option for relapsed or resistant MCL.

Personalized treatment based on mini patient-derived xenografts and WES/RNA sequencing in a patient with metastatic duodenal adenocarcinoma

Background

Treatment guidelines for a variety of cancers have been increasingly used in clinical practice, and have resulted in major improvement in patient outcomes. However, recommended regimens (even first-line treatments) are clearly not ideal for every patients. In the present study, we used mini patient-derived xenograft (mini-PDX) and next-generation sequencing to develop personalized treatment in a patient with metastatic duodenal adenocarcinoma.

Methods

Resected metachronous metastatic tumor tissues were implanted into SCID mice to determine the sensitivity to a variety of drug regimens. Mutation profiles were assessed using both DNA whole-exome sequencing (DNA–WES) and RNA sequencing. The results of the analyses were used to select optimal treatment for the patient with metastatic duodenal adenocarcinoma.

Results

Assessment with mini-PDX models took only 7 days. The results showed high sensitivity to S-1 plus cisplatin, gemcitabine plus cisplatin and everolimus alone. The patient received gemcitabine plus cisplatin initially, but the treatment was terminated due to toxicity. The patient was then switched to treatment with S-1 alone. The overall disease-free survival was 34 months. DNA–WES and RNA sequencing identified KRAS mutation (A146T), TP53 (C229Yfs*10) and RICTOR amplification in the metastatic duodenal adenocarcinoma. These findings provided further support to the results of the mini-PDX, and suggest mTOR inhibitors should be used if and when relapse eventually occurs in this patient.

Conclusions

Mini-PDX model combined with WES/RNA sequencing can rapidly assess drug sensitivity in cancer patients and reveal key genetic alterations. Further research on this technology for personalized therapy in patients with refractory malignant tumors is warranted.

Electronic supplementary material

The online version of this article (10.1186/s40880-018-0323-y) contains supplementary material, which is available to authorized users.