RX-5902, a novel β-catenin modulator, potentiates the efficacy of immune checkpoint inhibitors in preclinical models of triple-negative breast Cancer

A landscape of checkpoint blockade resistance in cancer: underlying mechanisms and current strategies to overcome resistance

The discovery of immune checkpoints and the development of immune checkpoint inhibitors (ICI) have achieved a durable response in advanced-stage cancer patients. However, there is still a high proportion of patients who do not benefit from ICI therapy due to a lack of response when first treated (primary resistance) or detection of disease progression months after objective response is observed (acquired resistance). Here, we review the current FDA-approved ICI for the treatment of certain solid malignancies, evaluate the contrasting responses to checkpoint blockade in different cancer types, explore the known mechanisms associated with checkpoint blockade resistance (CBR), and assess current strategies in the field that seek to overcome these mechanisms. In order to improve current therapies and develop new ones, the immunotherapy field still has an unmet need in identifying other molecules that act as immune checkpoints, and uncovering other mechanisms that promote CBR.

Quinoxaline derivatives: Recent discoveries and development strategies towards anticancer agents

Cancer is a leading cause of death and a major health problem worldwide. While many effective anticancer agents are available, most drugs currently on the market are not specific, raising issues like the common side effects of chemotherapy. However, recent research hold promises for the development of more efficient and safer anticancer drugs. Quinoxaline and its derivatives are becoming recognized as a novel class of chemotherapeutic agents with activity against different tumors. The present review compiles and discusses studies concerning the therapeutic potential of the anticancer activity of quinoxaline derivatives, covering articles published between January 2018 and January 2023.

WITHDRAWN: Supinoxin blocks Small Cell Lung Cancer Progression by Inhibiting Mitochondrial Respiration through the RNA Helicase DDX5

The authors have requested that this preprint be removed from Research Square.

Recent research and clinical progress of CTLA-4-based immunotherapy for breast cancer

Breast cancer is characterized by a high incidence rate and its treatment challenges, particularly in certain subtypes. Consequently, there is an urgent need for the development of novel therapeutic approaches. Immunotherapy utilizing immune checkpoint inhibitors (ICIs) is currently gaining momentum for the treatment of breast cancer. Substantial progress has been made in clinical studies employing cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) inhibitors for breast cancer, but the cure rates are relatively low. To improve the efficacy of CTLA-4-based therapy for breast cancer, further research is imperative to explore more effective immune-based treatment strategies. In addition to monotherapy, CTLA-4 inhibitors are also being investigated in combination with other ICIs or alternative medications. However, it should be noted that immune-based treatments may cause adverse events. This review focuses on the mechanisms of CTLA-4 inhibitor monotherapy or combination therapy in breast cancer. We systematically summarize the latest research and clinical advances in CTLA-4-based immunotherapy for breast cancer, providing new perspectives on the treatment of breast cancer. In addition, this review highlights the immune-related adverse events (irAEs) associated with CTLA-4 inhibitors, providing insights into the development of appropriate clinical tumor immunotherapy regimens and intervention strategies.

Modeling the Tumor Microenvironment and Cancer Immunotherapy in Next-Generation Humanized Mice

Cancer immunotherapy has brought significant clinical benefits to numerous patients with malignant disease. However, only a fraction of patients experiences complete and durable responses to currently available immunotherapies. This highlights the need for more effective immunotherapies, combination treatments and predictive biomarkers. The molecular properties of a tumor, intratumor heterogeneity and the tumor immune microenvironment decisively shape tumor evolution, metastasis and therapy resistance and are therefore key targets for precision cancer medicine. Humanized mice that support the engraftment of patient-derived tumors and recapitulate the human tumor immune microenvironment of patients represent a promising preclinical model to address fundamental questions in precision immuno-oncology and cancer immunotherapy. In this review, we provide an overview of next-generation humanized mouse models suitable for the establishment and study of patient-derived tumors. Furthermore, we discuss the opportunities and challenges of modeling the tumor immune microenvironment and testing a variety of immunotherapeutic approaches using human immune system mouse models.

Targeting DEAD-box RNA helicases: The emergence of molecular staples

RNA helicases constitute a large family of proteins that play critical roles in mediating RNA function. They have been implicated in all facets of gene expression pathways involving RNA, from transcription to processing, transport and translation, and storage and decay. There is significant interest in developing small molecule inhibitors to RNA helicases as some family members have been documented to be dysregulated in neurological and neurodevelopment disorders, as well as in cancers. Although different functional properties of RNA helicases offer multiple opportunities for small molecule development, molecular staples have recently come to the forefront. These bifunctional molecules interact with both protein and RNA components to lock them together, thereby imparting novel gain-of-function properties to their targets. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.

Genetic dysregulation of immunologic and oncogenic signaling pathways associated with tumor-intrinsic immune resistance: a molecular basis for combination targeted therapy-immunotherapy for cancer

Since the turn of the century, advances in targeted therapy and immunotherapy have revolutionized the treatment of cancer. Although these approaches have far outperformed traditional therapies in various clinical settings, both remain plagued by mechanisms of innate and acquired resistance that limit therapeutic efficacy in many patients. With a focus on tumor-intrinsic resistance to immunotherapy, this review highlights our current understanding of the immunologic and oncogenic pathways whose genetic dysregulation in cancer cells enables immune escape. Emphasis is placed on genomic, epigenomic, transcriptomic, and proteomic aberrations that influence the activity of these pathways in the context of immune resistance. Specifically, the role of pathways that govern interferon signaling, antigen processing and presentation, and immunologic cell death as determinants of tumor immune susceptibility are discussed. Likewise, mechanisms of tumor immune resistance mediated by dysregulated RAS-MAPK, WNT, PI3K-AKT-mTOR, and cell cycle pathways are described. Finally, this review highlights the ways in which recent insight into genetic dysregulation of these immunologic and oncogenic signaling pathways is informing the design of combination targeted therapy-immunotherapy regimens that aim to restore immune susceptibility of cancer cells by overcoming resistance mechanisms that often limit the success of monotherapies.

Testing Cancer Immunotherapeutics in a Humanized Mouse Model Bearing Human Tumors

Reversing the immunosuppressive nature of the tumor microenvironment is critical for the successful treatment of cancers with immunotherapy drugs. Murine cancer models are extremely limited in their diversity and suffer from poor translation to the clinic. To serve as a more physiological preclinical model for immunotherapy studies, this protocol has been developed to evaluate the treatment of human tumors in a mouse reconstituted with a human immune system. This unique protocol demonstrates the development of human immune system (HIS, "humanized") mice, followed by implantation of a human tumor, either a cell-line derived xenograft (CDX) or a patient derived xenograft (PDX). HIS mice are generated by injecting CD34+ human hematopoietic stem cells isolated from umbilical cord blood into neonatal BRGS (BALB/c Rag2-/- IL2RγC-/- NODSIRPα) highly immunodeficient mice that are also capable of accepting a xenogeneic tumor. The importance of the kinetics and characteristics of the human immune system development and tumor implantation is emphasized. Finally, an in-depth evaluation of the tumor microenvironment using flow cytometry is described. In numerous studies using this protocol, it was found that the tumor microenvironment of individual tumors is recapitulated in HIS-PDX mice; "hot" tumors exhibit large immune infiltration while "cold" tumors do not. This model serves as a testing ground for combination immunotherapies for a wide range of human tumors and represents an important tool in the quest for personalized medicine.

DDX5 and DDX17—multifaceted proteins in the regulation of tumorigenesis and tumor progression

DEAD-box (DDX)5 and DDX17, which belong to the DEAD-box RNA helicase family, are nuclear and cytoplasmic shuttle proteins. These proteins are expressed in most tissues and cells and participate in the regulation of normal physiological functions; their abnormal expression is closely related to tumorigenesis and tumor progression. DDX5/DDX17 participate in almost all processes of RNA metabolism, such as the alternative splicing of mRNA, biogenesis of microRNAs (miRNAs) and ribosomes, degradation of mRNA, interaction with long noncoding RNAs (lncRNAs) and coregulation of transcriptional activity. Moreover, different posttranslational modifications, such as phosphorylation, acetylation, ubiquitination, and sumoylation, endow DDX5/DDX17 with different functions in tumorigenesis and tumor progression. Indeed, DDX5 and DDX17 also interact with multiple key tumor-promoting molecules and participate in tumorigenesis and tumor progression signaling pathways. When DDX5/DDX17 expression or their posttranslational modification is dysregulated, the normal cellular signaling network collapses, leading to many pathological states, including tumorigenesis and tumor development. This review mainly discusses the molecular structure features and biological functions of DDX5/DDX17 and their effects on tumorigenesis and tumor progression, as well as their potential clinical application for tumor treatment.

A simple, rapid and low-cost qPCR assay for evaluating the severity of exosomal PD-L1-mediated T cell exhaustion in blood samples

A novel dual-aptamer activated proximity-induced qPCR assay was developed for the quantitative analysis of exosomal PD-L1 on T cell-exosome complexes in blood samples.

Multiple functions of the DEAD-box RNA helicase, DDX5 (p68), make DDX5 a superior oncogenic biomarker and target for targeted cancer therapy

DDX5 (p68) is a well-known multifunctional DEAD-box RNA helicase and a transcription cofactor. Since its initial discovery more than three decades ago, DDX5 is gradually recognized as a potential biomarker and target for the treatment of various cancer types. Studies over the years significantly expanded our understanding of the functional diversity of DDX5 in various cancer types and extended our knowledge of its Mechanism of Action (MOA). This provides a rationale for the development of novel cancer therapeutics by using DDX5 as a biomarker and a therapeutic target. However, while most of the published studies have found DDX5 to be an oncogenic target and a cancer treatment-resistant biomarker, a few studies have reported that in certain scenarios, DDX5 may act as a tumor suppressor. After careful review of all the available relevant studies in the literature, we found that the multiple functions of DDX5 make it both a superior independent oncogenic biomarker and target for targeted cancer therapy. In this article, we will summarize the relevant studies on DDX5 in literature with a careful analysis and discussion of any inconsistencies encountered, and then provide our conclusions with respect to understanding the MOA of FL118, a novel small molecule. We hope that such a review will stimulate further discussion on this topic and assist in developing better strategies to treat cancer by using DDX5 as both an oncogenic biomarker and therapeutic target.

Donor BMSC-derived small extracellular vesicles relieve acute rejection post-renal allograft through transmitting Loc108349490 to dendritic cells

Bone marrow-derived mesenchymal stem cell (BMSC)-derived small extracellular vesicles (sEVs) are potent candidates for the suppression of acute rejection post-renal allograft and have been reported to halt dendritic cells (DCs) maturation. However, whether BMSC-derived sEVs mitigate acute rejection post-renal allograft by targeting DCs is still unclear. In this study, donor BMSC-derived sEVs (sEVs) relieved the inflammatory response and suppressed mature DCs (mDCs) location in kidney grafts, and increased regulatory T (Treg) cell population in the spleens of the rats that underwent kidney allograft. In lipopolysaccharide (LPS)-stimulated immature DCs (imDCs), sEVs suppressed the maturation and migration of DCs and inactivated toll-like receptor 4 (TLR4) signaling. Compared with LPS-treated imDCs, imDCs treated with LPS+sEVs promoted CD4+ T cells differentiated toward Treg cells. Subsequently, we found that Loc108349490, a long non-coding RNA (lncRNA) abundant in sEVs, mediated the inhibitory effect of sEVs on DC maturation and migration by promoting TLR4 ubiquitination. In rats that underwent an allograft, Loc108349490 deficiency weakened the therapeutic effect of sEVs on acute rejection. The present study firstly found that sEVs alleviated acute rejection post-renal allograft by transferring lncRNA to DCs and screened out the functional lncRNA loaded in sEVs was Loc108349490.

DEAD-Box RNA Helicases and Genome Stability

DEAD-box RNA helicases are important regulators of RNA metabolism and have been implicated in the development of cancer. Interestingly, these helicases constitute a major recurring family of RNA-binding proteins important for protecting the genome. Current studies have provided insight into the connection between genomic stability and several DEAD-box RNA helicase family proteins including DDX1, DDX3X, DDX5, DDX19, DDX21, DDX39B, and DDX41. For each helicase, we have reviewed evidence supporting their role in protecting the genome and their suggested mechanisms. Such helicases regulate the expression of factors promoting genomic stability, prevent DNA damage, and can participate directly in the response and repair of DNA damage. Finally, we summarized the pathological and therapeutic relationship between DEAD-box RNA helicases and cancer with respect to their novel role in genome stability.

DEAD-Box RNA Helicases in Cell Cycle Control and Clinical Therapy

Cell cycle is regulated through numerous signaling pathways that determine whether cells will proliferate, remain quiescent, arrest, or undergo apoptosis. Abnormal cell cycle regulation has been linked to many diseases. Thus, there is an urgent need to understand the diverse molecular mechanisms of how the cell cycle is controlled. RNA helicases constitute a large family of proteins with functions in all aspects of RNA metabolism, including unwinding or annealing of RNA molecules to regulate pre-mRNA, rRNA and miRNA processing, clamping protein complexes on RNA, or remodeling ribonucleoprotein complexes, to regulate gene expression. RNA helicases also regulate the activity of specific proteins through direct interaction. Abnormal expression of RNA helicases has been associated with different diseases, including cancer, neurological disorders, aging, and autosomal dominant polycystic kidney disease (ADPKD) via regulation of a diverse range of cellular processes such as cell proliferation, cell cycle arrest, and apoptosis. Recent studies showed that RNA helicases participate in the regulation of the cell cycle progression at each cell cycle phase, including G1-S transition, S phase, G2-M transition, mitosis, and cytokinesis. In this review, we discuss the essential roles and mechanisms of RNA helicases in the regulation of the cell cycle at different phases. For that, RNA helicases provide a rich source of targets for the development of therapeutic or prophylactic drugs. We also discuss the different targeting strategies against RNA helicases, the different types of compounds explored, the proposed inhibitory mechanisms of the compounds on specific RNA helicases, and the therapeutic potential of these compounds in the treatment of various disorders.

Laboratory Mice - A Driving Force in Immunopathology and Immunotherapy Studies of Human Multiple Myeloma

Mouse models of human cancer provide an important research tool for elucidating the natural history of neoplastic growth and developing new treatment and prevention approaches. This is particularly true for multiple myeloma (MM), a common and largely incurable neoplasm of post-germinal center, immunoglobulin-producing B lymphocytes, called plasma cells, that reside in the hematopoietic bone marrow (BM) and cause osteolytic lesions and kidney failure among other forms of end-organ damage. The most widely used mouse models used to aid drug and immunotherapy development rely on in vivo propagation of human myeloma cells in immunodeficient hosts (xenografting) or myeloma-like mouse plasma cells in immunocompetent hosts (autografting). Both strategies have made and continue to make valuable contributions to preclinical myeloma, including immune research, yet are ill-suited for studies on tumor development (oncogenesis). Genetically engineered mouse models (GEMMs), such as the widely known Vκ*MYC, may overcome this shortcoming because plasma cell tumors (PCTs) develop de novo (spontaneously) in a highly predictable fashion and accurately recapitulate many hallmarks of human myeloma. Moreover, PCTs arise in an intact organism able to mount a complete innate and adaptive immune response and tumor development reproduces the natural course of human myelomagenesis, beginning with monoclonal gammopathy of undetermined significance (MGUS), progressing to smoldering myeloma (SMM), and eventually transitioning to frank neoplasia. Here we review the utility of transplantation-based and transgenic mouse models of human MM for research on immunopathology and -therapy of plasma cell malignancies, discuss strengths and weaknesses of different experimental approaches, and outline opportunities for closing knowledge gaps, improving the outcome of patients with myeloma, and working towards a cure.

Aberrations of Chromosomes 1 and 16 in Breast Cancer: A Framework for Cooperation of Transcriptionally Dysregulated Genes

Derivative chromosome der(1;16), isochromosome 1q, and deleted 16q-producing arm-level 1q-gain and/or 16q-loss-are recurrent cytogenetic abnormalities in breast cancer, but their exact role in determining the malignant phenotype is still largely unknown. We exploited The Cancer Genome Atlas (TCGA) data to generate and analyze groups of breast invasive carcinomas, called 1,16-chromogroups, that are characterized by a pattern of arm-level somatic copy number aberrations congruent with known cytogenetic aberrations of chromosome 1 and 16. Substantial differences were found among 1,16-chromogroups in terms of other chromosomal aberrations, aneuploidy scores, transcriptomic data, single-point mutations, histotypes, and molecular subtypes. Breast cancers with a co-occurrence of 1q-gain and 16q-loss can be distinguished in a "low aneuploidy score" group, congruent to der(1;16), and a "high aneuploidy score" group, congruent to the co-occurrence of isochromosome 1q and deleted 16q. Another three groups are formed by cancers showing separately 1q-gain or 16q-loss or no aberrations of 1q and 16q. Transcriptome comparisons among the 1,16-chromogroups, integrated with functional pathway analysis, suggested the cooperation of overexpressed 1q genes and underexpressed 16q genes in the genesis of both ductal and lobular carcinomas, thus highlighting the putative role of genes encoding gamma-secretase subunits (APH1A, PSEN2, and NCSTN) and Wnt enhanceosome components (BCL9 and PYGO2) in 1q, and the glycoprotein E-cadherin (CDH1), the E3 ubiquitin-protein ligase WWP2, the deubiquitinating enzyme CYLD, and the transcription factor CBFB in 16q. The analysis of 1,16-chromogroups is a strategy with far-reaching implications for the selection of cancer cell models and novel experimental therapies.

Testing Cancer Immunotherapy in a Human Immune System Mouse Model: Correlating Treatment Responses to Human Chimerism, Therapeutic Variables and Immune Cell Phenotypes

Over the past decade, immunotherapies have revolutionized the treatment of cancer. Although the success of immunotherapy is remarkable, it is still limited to a subset of patients. More than 1500 clinical trials are currently ongoing with a goal of improving the efficacy of immunotherapy through co-administration of other agents. Preclinical, small-animal models are strongly desired to increase the pace of scientific discovery, while reducing the cost of combination drug testing in humans. Human immune system (HIS) mice are highly immune-deficient mouse recipients rtpeconstituted with human hematopoietic stem cells. These HIS-mice are capable of growing human tumor cell lines and patient-derived tumor xenografts. This model allows rapid testing of multiple, immune-related therapeutics for tumors originating from unique clinical samples. Using a cord blood-derived HIS-BALB/c-Rag2nullIl2rγnullSIRPαNOD (BRGS) mouse model, we summarize our experiments testing immune checkpoint blockade combinations in these mice bearing a variety of human tumors, including breast, colorectal, pancreatic, lung, adrenocortical, melanoma and hematological malignancies. We present in-depth characterization of the kinetics and subsets of the HIS in lymph and non-lymph organs and relate these to protocol development and immune-related treatment responses. Furthermore, we compare the phenotype of the HIS in lymph tissues and tumors. We show that the immunotype and amount of tumor infiltrating leukocytes are widely-variable and that this phenotype is tumor-dependent in the HIS-BRGS model. We further present flow cytometric analyses of immune cell subsets, activation state, cytokine production and inhibitory receptor expression in peripheral lymph organs and tumors. We show that responding tumors bear human infiltrating T cells with a more inflammatory signature compared to non-responding tumors, similar to reports of "responding" patients in human immunotherapy clinical trials. Collectively these data support the use of HIS mice as a preclinical model to test combination immunotherapies for human cancers, if careful attention is taken to both protocol details and data analysis.