Dinaciclib induces immunogenic cell death and enhances anti-PD1-mediated tumor suppression

Engineering nanomedicines for immunogenic eradication of cancer cells: Recent trends and synergistic approaches

Resistance to cancer immunotherapy is mainly attributed to poor tumor immunogenicity as well as the immunosuppressive tumor microenvironment (TME) leading to failure of immune response. Numerous therapeutic strategies including chemotherapy, radiotherapy, photodynamic, photothermal, magnetic, chemodynamic, sonodynamic and oncolytic therapy, have been developed to induce immunogenic cell death (ICD) of cancer cells and thereby elicit immunogenicity and boost the antitumor immune response. However, many challenges hamper the clinical application of ICD inducers resulting in modest immunogenic response. Here, we outline the current state of using nanomedicines for boosting ICD of cancer cells. Moreover, synergistic approaches used in combination with ICD inducing nanomedicines for remodeling the TME via targeting immune checkpoints, phagocytosis, macrophage polarization, tumor hypoxia, autophagy and stromal modulation to enhance immunogenicity of dying cancer cells were analyzed. We further highlight the emerging trends of using nanomaterials for triggering amplified ICD-mediated antitumor immune responses. Endoplasmic reticulum localized ICD, focused ultrasound hyperthermia, cell membrane camouflaged nanomedicines, amplified reactive oxygen species (ROS) generation, metallo-immunotherapy, ion modulators and engineered bacteria are among the most innovative approaches. Various challenges, merits and demerits of ICD inducer nanomedicines were also discussed with shedding light on the future role of this technology in improving the outcomes of cancer immunotherapy.

ICG-labeled PD-L1-antagonistic affibody dimer for tumor imaging and enhancement of tumor photothermal-immunotherapy

In clinical practice, tumor-targeting diagnosis and immunotherapy against programmed death ligand 1 (PD-L1) have a significant impact. In this research, a PD-L1-antagonistic affibody dimer (ZPD-L1) was successfully prepared through Escherichia coli expression system, and conjugated with the photosensitizer of ICG via N-hydroxysuccinimide (NHS) ester to develop a novel tumor-targeting agent (ICG-ZPD-L1) for both tumor imaging diagnosis and photothermal-immunotherapy simultaneously. In vitro, ZPD-L1 could specifically bind to PD-L1-positive LLC and MC38 tumor cells, and ICG-ZPD-L1-mediated photothermal therapy (PTT) also showed excellent phototoxicity to these tumor cells. In vivo, ICG-ZPD-L1 selectively enriched into the PD-L1-positive MC38 tumor tissues, and the high-contrast optical imaging of tumors was obtained. ICG-ZPD-L1-mediated PTT exhibited a potent anti-tumor effect in vivo due to its remarkable photothermal properties. Furthermore, ICG-ZPD-L1-mediated PTT significantly induced the immunogenic cell death (ICD) of primary tumors, promoted maturation of dendritic cells (DCs), up-regulated anti-tumor immune response, enhanced immunotherapy, and superiorly inhibited the growth of metastatic tumors. In addition, ICG-ZPD-L1 showed favorable biosafety throughout the brief duration of treatment. In summary, these results suggest that ICG-ZPD-L1 is a multifunctional tumor-targeting drug integrating tumor imaging diagnosis and photothermal-immunotherapy, and has great guiding significance for the diagnosis and treatment of clinical PD-L1-positive tumor patients.

CDK9 inhibition as an effective therapy for small cell lung cancer

Treatment-naïve small cell lung cancer (SCLC) is typically susceptible to standard-of-care chemotherapy consisting of cisplatin and etoposide recently combined with PD-L1 inhibitors. Yet, in most cases, SCLC patients develop resistance to first-line therapy and alternative therapies are urgently required to overcome this resistance. In this study, we tested the efficacy of dinaciclib, an FDA-orphan drug and inhibitor of the cyclin-dependent kinase (CDK) 9, among other CDKs, in SCLC. Furthermore, we report on a newly developed, highly specific CDK9 inhibitor, VC-1, with tumour-killing activity in SCLC. CDK9 inhibition displayed high killing potential in a panel of mouse and human SCLC cell lines. Mechanistically, CDK9 inhibition led to a reduction in MCL-1 and cFLIP anti-apoptotic proteins and killed cells, almost exclusively, by intrinsic apoptosis. While CDK9 inhibition did not synergise with chemotherapy, it displayed high efficacy in chemotherapy-resistant cells. In vivo, CDK9 inhibition effectively reduced tumour growth and improved survival in both autochthonous and syngeneic SCLC models. Together, this study shows that CDK9 inhibition is a promising therapeutic agent against SCLC and could be applied to chemo-refractory or resistant SCLC.

Zebularine potentiates anti-tumor immunity by inducing tumor immunogenicity and improving antigen processing through cGAS-STING pathway

DNA methylation is an important epigenetic mechanism involved in the anti-tumor immune response, and DNA methyltransferase inhibitors (DNMTi) have achieved impressive therapeutic outcomes in patients with certain cancer types. However, it is unclear how inhibition of DNA methylation bridges the innate and adaptive immune responses to inhibit tumor growth. Here, we report that DNMTi zebularine reconstructs tumor immunogenicity, in turn promote dendritic cell maturation, antigen-presenting cell activity, tumor cell phagocytosis by APCs, and efficient T cell priming. Further in vivo and in vitro analyses reveal that zebularine stimulates cGAS-STING-NF-κB/IFNβ signaling to enhance tumor cell immunogenicity and upregulate antigen processing and presentation machinery (AgPPM), which promotes effective CD4+ and CD8+ T cell-mediated killing of tumor cells. These findings support the use of combination regimens that include DNMTi and immunotherapy for cancer treatment.

Emerging role of immunogenic cell death in cancer immunotherapy

Cancer immunotherapy, such as immune checkpoint blockade (ICB), has emerged as a groundbreaking approach for effective cancer treatment. Despite its considerable potential, clinical studies have indicated that the current response rate to cancer immunotherapy is suboptimal, primarily attributed to low immunogenicity in certain types of malignant tumors. Immunogenic cell death (ICD) represents a form of regulated cell death (RCD) capable of enhancing tumor immunogenicity and activating tumor-specific innate and adaptive immune responses in immunocompetent hosts. Therefore, gaining a deeper understanding of ICD and its evolution is crucial for developing more effective cancer therapeutic strategies. This review focuses exclusively on both historical and recent discoveries related to ICD modes and their mechanistic insights, particularly within the context of cancer immunotherapy. Our recent findings are also highlighted, revealing a mode of ICD induction facilitated by atypical interferon (IFN)-stimulated genes (ISGs), including polo-like kinase 2 (PLK2), during hyperactive type I IFN signaling. The review concludes by discussing the therapeutic potential of ICD, with special attention to its relevance in both preclinical and clinical settings within the field of cancer immunotherapy.

Advances in traditional herbal formulation based nano-vaccine for cancer immunotherapy: Unraveling the enigma of complex tumor environment and multidrug resistance

Cancer is attributed to uncontrolled cell growth and is among the leading causes of death with no known effective treatment while complex tumor microenvironment (TME) and multidrug resistance (MDR) are major challenges for developing an effective therapeutic strategy. Advancement in cancer immunotherapy has been limited by the over-activation of the host immune response that ultimately affects healthy tissues or organs and leads to a feeble response of the patient's immune system against tumor cells. Besides, traditional herbal medicines (THM) have been well-known for their essential role in the treatment of cancer and are considered relatively safe due to their compatibility with the human body. Yet, poor solubility, low bio-availability, and lack of understanding about their pathophysiological mechanism halt their clinical application. Moreover, considering the complex TME and drug resistance, the most precarious and least discussed concerns for developing THM-based nano-vaccination, are identification of specific biomarkers for drug inhibitory protein and targeted delivery of bioactive ingredients of THM on the specific sites in tumor cells. The concept of THM-based nano-vaccination indicates immunomodulation of TME by THM-based bioactive adjuvants, exerting immunomodulatory effects, via targeted inhibition of key proteins involved in the metastasis of cancer. However, this concept is at its nascent stage and very few preclinical studies provided the evidence to support clinical translation. Therefore, we attempted to capsulize previously reported studies highlighting the role of THM-based nano-medicine in reducing the risk of MDR and combating complex tumor environments to provide a reference for future study design by discussing the challenges and opportunities for developing an effective and safe therapeutic strategy against cancer.

CDK inhibition results in pharmacologic BRCAness increasing sensitivity to olaparib in BRCA1-WT and olaparib resistant in Triple Negative Breast Cancer

One in three Triple Negative Breast Cancer (TNBC) is Homologous Recombination Deficient (HRD) and susceptible to respond to PARP inhibitor (PARPi), however, resistance resulting from functional HR restoration is frequent. Thus, pharmacologic approaches that induce HRD are of interest. We investigated the effectiveness of CDK-inhibition to induce HRD and increase PARPi sensitivity of TNBC cell lines and PDX models. Two CDK-inhibitors (CDKi), the broad range dinaciclib and the CDK12-specific SR-4835, strongly reduced the expression of key HR genes and impaired HR functionality, as illustrated by BRCA1 and RAD51 nuclear foci obliteration. Consequently, both CDKis showed synergism with olaparib, as well as with cisplatin and gemcitabine, in a range of TNBC cell lines and particularly in olaparib-resistant models. In vivo assays on PDX validated the efficacy of dinaciclib which increased the sensitivity to olaparib of 5/6 models, including two olaparib-resistant and one BRCA1-WT model. However, no olaparib response improvement was observed in vivo with SR-4835. These data support that the implementation of CDK-inhibitors could be effective to sensitize TNBC to olaparib as well as possibly to cisplatin or gemcitabine.

Nanodrug modified with engineered cell membrane targets CDKs to activate aPD-L1 immunotherapy against liver metastasis of immune-desert colon cancer

Immunotherapy based on the PD-1/PD-L1 axis blockade has no benefit for patients diagnosed with colon cancer liver metastasis (CCLM) for the microsatellite stable/proficient mismatch repair (MSS/pMMR)) subtype, which is known as an immune-desert cancer featuring poor immunogenicity and insufficient CD8+ T cell infiltration in the tumor microenvironment. Here, a multifunctional nanodrug carrying a cyclin-dependent kinase (CDK)1/2/5/9 inhibitor and PD-L1 antibody is prepared to boost the immune checkpoint blockade (ICB)-based immunotherapy against MSS/pMMR CCLM via reversing the immunosuppressive tumor microenvironment. To enhance the MSS/pMMR CCLM-targeting efficacy, we modify the nanodrug with PD-L1 knockout cell membrane of this colon cancer subtype. First, CDKs inhibitor delivered by nanodrug down-regulates phosphorylated retinoblastoma and phosphorylated RNA polymerase II and meanwhile arrests the G2/M cell cycle in CCLM to promote immunogenic signal release, stimulate dendritic cell maturation, and enhance CD8+ T cell infiltration. Moreover, CDKi suppresses the secretion of immunosuppressive cytokines in tumor-associated myeloid cells sensitizing ICB therapy in CCLM. Notably, the great efficacy to activate immune responses is demonstrated in the patient-derived xenograft model and the patient-derived organoid model as well, revealing a clinical application potential. Overall, our study represents a promising therapeutic approach for targeting liver metastasis, remolding the tumor immune microenvironment (TIME), and enhancing the response of MSS/pMMR CCLM to boost ICB immunotherapy.

Systematic investigation of chemo-immunotherapy synergism to shift anti-PD-1 resistance in cancer

Chemo-immunotherapy combinations have been regarded as one of the most practical ways to improve immunotherapy response in cancer patients. In this study, we integrate the transcriptomics data from anti-PD-1-treated tumors and compound-treated cancer cell lines to systematically screen for chemo-immunotherapy synergisms in silico. Through analyzing anti-PD-1 induced expression changes in patient tumors, we develop a shift ability score to measure if a chemotherapy or a small molecule inhibitor treatment can shift anti-PD-1 resistance in tumor cells. By applying shift ability analysis to 41,321 compounds and 16,853 shRNA treated cancer cell lines transcriptomic data, we characterize the landscape of chemo-immunotherapy synergism and experimentally validated a mitochondrial RNA-dependent mechanism for drug-induced immune activation in tumor. Our study represents an effort to mechanistically characterize chemo-immunotherapy synergism and will facilitate future pre-clinical and clinical studies.

Dinaciclib inhibits the growth of acute myeloid leukemia cells through either cell cycle-related or ERK1/STAT3/MYC pathways

Although immature differentiation and uncontrolled proliferation of hematopoietic stem cells are thought to be the primary mechanisms of acute myeloid leukemia (AML), the pathophysiology in most cases remains unclear. Dinaciclib, a selective small molecule targeting multiple cyclin-dependent kinases (CDKs), is currently being evaluated in oncological clinical trials. Despite the proven anticancer potential of dinaciclib, the differential molecular mechanisms by which it inhibits the growth of different AML cell lines remain unclear. In the current study, we treated HL-60 and KG-1 AML cell lines with dinaciclib and investigated the potential mechanisms of dinaciclib-induced AML cell growth inhibition using flow cytometry and western blotting assays. Data from HL-60 and KG-1 AML cells were validated using human primary AML cells. The results showed that the growth inhibitory effect of dinaciclib was more sensitive in HL-60 cells (IC50: 8.46 nM) than in KG-1 cells (IC50: 14.37 nM). The protein decline in Cyclin A/B and CDK1 and cell cycle arrest in the G2/M phase were more profound in HL-60 cells, corresponding to its growth inhibition. Although the growth inhibition of KG-1 cells by dinaciclib was still pronounced, the cell cycle-associated proteins were relatively insensitive. In addition to cell cycle regulation, the activation/expression of ERK1/STAT3/MYC signaling was significantly reduced by dinaciclib in KG-1 cells compared with that in HL-60 cells. Regarding the results of primary AML cells, we observed ERK1/STAT3/MYC inhibition and cell cycle regulation in different patients. These findings suggest that the cell cycle-associated and ERK1/STAT3/MYC signaling pathways might be two distinct mechanisms by which dinaciclib inhibits AML cells, which could facilitate the development of combination therapy for AML in the future.

Macrophage-Capturing Self-Assembly Photosensitizer Nanoparticles Induces Immune Microenvironment Re-Programming and Golgi-Responsive Immunogenic Cell Death in Head and Neck Carcinoma

Head and neck carcinoma treatment is shifted toward the combination of therapy causing immune checkpoint blockade (ICB) and immunogenic cell death. In this study, a CSFRi-chimeric TAMCSFR+-targeting extracellular vesicle (EV@CSFRi) platform is developed and designed an intracellular protoporphyrin conjugated with RVRR peptide sequence for furin-cleavage to perform Golgi-targeting and generating ROS (GT-RG). The graphical abstract illustrates the self-assembly of GT-RG nanoparticles into nanofiber through the hydrophily of RVRR and hydrophobicity of RG, and the red line indicates the site of furin cleavage. As is shown in the Graphical abstract, the Golgi-targeting Protoporphyrin-RVRR platform is composed with CSFRi-chimeric extracellular vesicles and forms the tumor-responsive TAM-reprogramming bilayers (GT-RGEV@CSFRi). The GT-RGEV@CSFRi acted as a multifunctional theranostic platform, which can induce immunogenic cell death and further help modulate TAM, thus suppressing the HNC xenograft model by combination therapy with anti-PD-1.

Centrosomes and associated proteins in pathogenesis and treatment of breast cancer

Breast cancer is the most prevalent malignancy among women worldwide. Despite significant advances in treatment, it remains one of the leading causes of female mortality. The inability to effectively treat advanced and/or treatment-resistant breast cancer demonstrates the need to develop novel treatment strategies and targeted therapies. Centrosomes and their associated proteins have been shown to play key roles in the pathogenesis of breast cancer and thus represent promising targets for drug and biomarker development. Centrosomes are fundamental cellular structures in the mammalian cell that are responsible for error-free execution of cell division. Centrosome amplification and aberrant expression of its associated proteins such as Polo-like kinases (PLKs), Aurora kinases (AURKs) and Cyclin-dependent kinases (CDKs) have been observed in various cancers, including breast cancer. These aberrations in breast cancer are thought to cause improper chromosomal segregation during mitosis, leading to chromosomal instability and uncontrolled cell division, allowing cancer cells to acquire new genetic changes that result in evasion of cell death and the promotion of tumor formation. Various chemical compounds developed against PLKs and AURKs have shown meaningful antitumorigenic effects in breast cancer cells in vitro and in vivo. The mechanism of action of these inhibitors is likely related to exacerbation of numerical genomic instability, such as aneuploidy or polyploidy. Furthermore, growing evidence demonstrates enhanced antitumorigenic effects when inhibitors specific to centrosome-associated proteins are used in combination with either radiation or chemotherapy drugs in breast cancer. This review focuses on the current knowledge regarding the roles of centrosome and centrosome-associated proteins in breast cancer pathogenesis and their utility as novel targets for breast cancer treatment.

Establishment of an immunogenic cell death-related model for prognostic prediction and identification of therapeutic targets in endometrial carcinoma

OBJECTIVE

Studies have firmly established the pivotal role of the immunogenic cell death (ICD) in the development of tumors. This study seeks to develop a risk model related to ICD to predict the prognosis of patients with endometrial carcinoma (EC).

MATERIALS AND METHODS

RNA-seq data of EC retrieved from TCGA database were analyzed using R software. We determined clusters based on ICD-related genes (ICDRGs) expression levels. Cox and LASSO analyses were further used to build the prediction model, and its accuracy was evaluated in the train and validation sets. Finally, in vitro and in vivo experiments were conducted to confirm the impact of the high-risk gene IFNA2 on EC.

RESULTS

Patients were sorted into two ICD clusters, with survival analysis revealing divergent prognoses between the clusters. The Cox regression analysis identified prognostic risk genes, and the LASSO analysis constructed a model based on 9 of these genes. Notably, this model displayed excellent predictive accuracy when validated. Finally, increased IFNA2 levels led to decreased vitality, proliferation, and invasiveness in vitro. IFNA2 also has significant tumor inhibiting effect in vivo.

CONCLUSIONS

The ICD-related model can accurately predict the prognosis of patients with EC, and IFNA2 may be a potential treatment target.

Unique vulnerability of RAC1-mutant melanoma to combined inhibition of CDK9 and immune checkpoints

RAC1P29S is the third most prevalent hotspot mutation in sun-exposed melanoma. RAC1 alterations in cancer are correlated with poor prognosis, resistance to standard chemotherapy, and insensitivity to targeted inhibitors. Although RAC1P29S mutations in melanoma and RAC1 alterations in several other cancers are increasingly evident, the RAC1-driven biological mechanisms contributing to tumorigenesis remain unclear. Lack of rigorous signaling analysis has prevented identification of alternative therapeutic targets for RAC1P29S-harboring melanomas. To investigate the RAC1P29S-driven effect on downstream molecular signaling pathways, we generated an inducible RAC1P29S expression melanocytic cell line and performed RNA-sequencing (RNA-seq) coupled with multiplexed kinase inhibitor beads and mass spectrometry (MIBs/MS) to establish enriched pathways from the genomic to proteomic level. Our proteogenomic analysis identified CDK9 as a potential new and specific target in RAC1P29S-mutant melanoma cells. In vitro, CDK9 inhibition impeded the proliferation of in RAC1P29S-mutant melanoma cells and increased surface expression of PD-L1 and MHC Class I proteins. In vivo, combining CDK9 inhibition with anti-PD-1 immune checkpoint blockade significantly inhibited tumor growth only in melanomas that expressed the RAC1P29S mutation. Collectively, these results establish CDK9 as a novel target in RAC1-driven melanoma that can further sensitize the tumor to anti-PD-1 immunotherapy.

Dinaciclib exerts a tumor-suppressing effect via β-catenin/YAP axis in pancreatic ductal adenocarcinoma

Dinaciclib, a cyclin-dependent kinase-5 (CDK5) inhibitor, has significant anti-tumor properties. However, the precise mechanism of dinaciclib requires further investigation. Herein, we investigated the anti-tumor functions and molecular basis of dinaciclib in pancreatic ductal adenocarcinoma (PDAC). PDAC and matched para-carcinoma specimens were collected from the patients who underwent radical resection. Immunohistochemistry was performed to assess CDK5 expression. Cell proliferation ability, migration, and invasion were measured using Cell Counting Kit-8, wound healing, and transwell assay, respectively. The cell cycle and apoptosis were assessed using flow cytometry. Gene expression was examined using RNA-seq and quantitative real-time PCR. Protein expression of proteins was measured by western blot analysis and immunofluorescence microscopy. Tumor-bearing mice were intraperitoneally injected with dinaciclib. CDK5 is highly expressed in PDAC. The expression level of CDK5 was significantly related to tumor size, T stage, and the American Joint Committee on Cancer stage. High CDK5 expression can predict poor survival in PDAC patients. In addition, the expression level of CDK5 might be an independent prognostic factor for PDAC patients. Dinaciclib inhibits the growth and motility of PDAC cells and induces apoptosis and cell cycle arrest in the G2/M phase. Mechanistically, dinaciclib down-regulated yes-associated protein (YAP) mRNA and protein expression by reducing β-catenin expression. Moreover, dinaciclib significantly inhibited PDAC cell growth in vivo . Our findings reveal a novel anti-tumor mechanism of dinaciclib in which it decreases YAP expression by down-regulating β-catenin at the transcriptional level rather than by activating Hippo pathway-mediated phosphorylation-dependent degradation.

HMGB1 in the interplay between autophagy and apoptosis in cancer

Lysosome-mediated autophagy and caspase-dependent apoptosis are dynamic processes that maintain cellular homeostasis, ensuring cell health and functionality. The intricate interplay and reciprocal regulation between autophagy and apoptosis are implicated in various human diseases, including cancer. High-mobility group box 1 (HMGB1), a nonhistone chromosomal protein, plays a pivotal role in coordinating autophagy and apoptosis levels during tumor initiation, progression, and therapy. The regulation of autophagy machinery and the apoptosis pathway by HMGB1 is influenced by various factors, including the protein's subcellular localization, oxidative state, and interactions with binding partners. In this narrative review, we provide a comprehensive overview of the structure and function of HMGB1, with a specific focus on the interplay between autophagic degradation and apoptotic death in tumorigenesis and cancer therapy. Gaining a comprehensive understanding of the significance of HMGB1 as a biomarker and its potential as a therapeutic target in tumor diseases is crucial for advancing our knowledge of cell survival and cell death.

Dendritic cells: the yin and yang in disease progression

Dendritic cells (DCs) are antigen presenting cells that link innate and adaptive immunity. DCs have been historically considered as the most effective and potent cell population to capture, process and present antigens to activate naïve T cells and originate favorable immune responses in many diseases, such as cancer. However, in the last decades, it has been observed that DCs not only promote beneficial responses, but also drive the initiation and progression of some pathologies, including inflammatory bowel disease (IBD). In line with those notions, different therapeutic approaches have been tested to enhance or impair the concentration and role of the different DC subsets. The blockade of inhibitory pathways to promote DCs or DC-based vaccines have been successfully assessed in cancer, whereas the targeting of DCs to inhibit their functionality has proved to be favorable in IBD. In this review, we (a) described the general role of DCs, (b) explained the DC subsets and their role in immunogenicity, (c) analyzed the role of DCs in cancer and therapeutic approaches to promote immunogenic DCs and (d) analyzed the role of DCs in IBD and therapeutic approaches to reduced DC-induced inflammation. Therefore, we aimed to highlight the "yin-yang" role of DCs to improve the understand of this type of cells in disease progression.

Using immunogenic cell death to improve anticancer efficacy of immune checkpoint inhibitors: From basic science to clinical application

Even though the discovery of immune checkpoint inhibitors (ICIs) has revolutionized cancer treatment, a high proportion of patients do not respond. Moreover, some types of cancers are refractory to these treatments. Thus, the need to find predictive biomarkers of efficacy and to evaluate the association with other treatments, such as chemotherapy or radiotherapy, appears to be essential. Because ICIs reactivate or maintain an active status of T cells, one possibility is to combine these treatments with therapies that engage an immune response against tumor cells. Thus, by inducing immunogenic cell death (ICD) of cancer cells, some conventional anticancer treatments induce such immune response and may have an interest to be combined with ICIs. In this review, we explore preclinical studies and clinical trials that evaluate the combination of ICIs with ICD inducers. More than inducing ICD, some of these treatments appear to modulate the tumor microenvironment and more particularly to inhibit immunosuppression, thus improving treatment efficacy.

Targeting acid ceramidase enhances antitumor immune response in colorectal cancer

INTRODUCTION

Acid ceramidase (hereafter referred as ASAH1) is an enzyme in sphingolipid metabolism that converts pro-survival ceramide into sphingosine. ASAH1 has been shown to be overexpressed in certain cancers. However, the role of ASAH1 in colorectal cancer still remain elusive.

OBJECTIVE

The present study is aimed to understand how ASAH1 regulates colorectal cancer (CRC) progression and resistance to checkpoint inhibitor therapy.

METHODS

Both pharmacological and genetic silencing of ASAH1 was used in the study. In vitro experiments were done on human and mouse CRC cell lines. The in vivo studies were conducted in NOD-SCID and BALB/c mice models. The combination of ASAH1 inhibitor and checkpoint inhibitor was tested using a syngeneic tumor model of CRC. Transcriptomic and metabolomic analyses were done to understand the effect of ASAH1 silencing.

RESULTS

ASAH1 is overexpressed in human CRC cases, and silencing the expression resulted in the induction of immunological cell death (ICD) and mitochondrial stress. The ASAH1 inhibitor (LCL-521), either as monotherapy or in combination with an anti-PD-1 antibody, resulted in reduction of tumors and, through induction of type I and II interferon response, activation of M1 macrophages and T cells, leading to enhanced infiltration of cytotoxic T cells. Our findings supported that the combination of LCL-521 and ICIs, which enhances the antitumor responses, and ASAH1 can be a druggable target in CRC.

The role of ARL4C in predicting prognosis and immunotherapy drug susceptibility in pan-cancer analysis

Background: ARLs, which are a class of small GTP-binding proteins, play a crucial role in facilitating tumor tumorigenesis and development. ARL4C, a vital member of the ARLs family, has been implicated in the progression of tumors, metastatic dissemination, and development of resistance to therapeutic drugs. Nevertheless, the precise functional mechanisms of ARL4C concerning tumor prognosis and immunotherapy drug susceptibility remain elusive. Methods: By combining the GTEx and TCGA databases, the presence of ARL4C was examined in 33 various types of cancer. Immunohistochemistry and immunofluorescence staining techniques were utilized to confirm the expression of ARL4C in particular tumor tissues. Furthermore, the ESTIMATE algorithm and TIMER2.0 database were utilized to analyze the tumor microenvironment and immune infiltration associated with ARL4C. The TISCH platform facilitated the utilization of single-cell RNA-seq datasets for further analysis. ARL4C-related immune escape was investigated using the TISMO tool. Lastly, drug sensitivity analysis was conducted to assess the sensitivity of different types of tumors to compounds based on the varying levels of ARL4C expression. Results: The study found that ARL4C was highly expressed in 23 different types of cancer. Moreover, the presence of high ARL4C expression was found to be associated with a poor prognosis in BLCA, COAD, KIRP, LGG, and UCEC. Notably, ARL4C was also expressed in immune cells, and its high expression was found to be correlated with cancer immune activation. Most importantly, the drug sensitivity analysis revealed a positive correlation between ARL4C expression and the heightened sensitivity of tumors to Staurosporine, Midostaurin, and Nelarabine. Conclusion: The findings from our study indicate that the expression level of ARL4C may exert an influence on cancer development, prognosis, and susceptibility to immunotherapy drugs. In addition, the involvement of ARL4C in the tumor immune microenvironment has expanded the concept of ARL4C-targeted immunotherapy.

Cyclin-dependent kinase-9 in B-cell malignancies: pathogenic role and therapeutic implications

Cyclin-dependent kinases (CDK) regulate cell cycle and transcriptional activity. Pan-CDK inhibitors demonstrated early efficacy in lymphoid malignancies, but also have been associated with narrow therapeutic index. Among transcriptional CDKs, CDK7 and CDK9 emerged as promising targets. CDK9 serves as a component of P-TEFb elongation complex and thus is indispensable in mRNA transcription. Selective CDK9 inhibitors demonstrated pre-clinical efficacy in in vitro and in vivo models of B-cell non-Hodgkin lymphoma. CDK9 inhibition results in transcriptional pausing with rapid downmodulation of short-lived oncogenic proteins, e.g. Myc and Mcl-1, followed by cell apoptosis. Early phase clinical trials established safety of CDK9 inhibitors, with manageable neutropenia, infections and gastrointestinal toxicities. In this review, we summarize the rationale of targeting CDK9 in lymphoid malignancies, as well as pre-clinical and early clinical data with pan-CDK and selective CDK9 inhibitors.

Opaganib (ABC294640) Induces Immunogenic Tumor Cell Death and Enhances Checkpoint Antibody Therapy

Antibody-based cancer drugs that target the checkpoint proteins CTLA-4, PD-1 and PD-L1 provide marked improvement in some patients with deadly diseases such as lung cancer and melanoma. However, most patients are either unresponsive or relapse following an initial response, underscoring the need for further improvement in immunotherapy. Certain drugs induce immunogenic cell death (ICD) in tumor cells in which the dying cells promote immunologic responses in the host that may enhance the in vivo activity of checkpoint antibodies. Sphingolipid metabolism is a key pathway in cancer biology, in which ceramides and sphingosine 1-phosphate (S1P) regulate tumor cell death, proliferation and drug resistance, as well as host inflammation and immunity. In particular, sphingosine kinases are key sites for manipulation of the ceramide/S1P balance that regulates tumor cell proliferation and sensitivity to radiation and chemotherapy. We and others have demonstrated that inhibition of sphingosine kinase-2 by the small-molecule investigational drug opaganib (formerly ABC294640) kills tumor cells and increases their sensitivities to other drugs and radiation. Because sphingolipids have been shown to regulate ICD, opaganib may induce ICD and improve the efficacy of checkpoint antibodies for cancer therapy. This was demonstrated by showing that in vitro treatment with opaganib increases the surface expression of the ICD marker calreticulin on a variety of tumor cell types. In vivo confirmation was achieved using the gold standard immunization assay in which B16 melanoma, Lewis lung carcinoma (LLC) or Neuro-2a neuroblastoma cells were treated with opaganib in vitro and then injected subcutaneously into syngeneic mice, followed by implantation of untreated tumor cells 7 days later. In all cases, immunization with opaganib-treated cells strongly suppressed the growth of subsequently injected tumor cells. Interestingly, opaganib treatment induced crossover immunity in that opaganib-treated B16 cells suppressed the growth of both untreated B16 and LLC cells and opaganib-treated LLC cells inhibited the growth of both untreated LLC and B16 cells. Next, the effects of opaganib in combination with a checkpoint antibody on tumor growth in vivo were assessed. Opaganib and anti-PD-1 antibody each slowed the growth of B16 tumors and improved mouse survival, while the combination of opaganib plus anti-PD-1 strongly suppressed tumor growth and improved survival (p < 0.0001). Individually, opaganib and anti-CTLA-4 antibody had modest effects on the growth of LLC tumors and mouse survival, whereas the combination of opaganib with anti-CTLA-4 substantially inhibited tumor growth and increased survival (p < 0.001). Finally, the survival of mice bearing B16 tumors was only marginally improved by opaganib or anti-PD-L1 antibody alone but was nearly doubled by the drugs in combination (p < 0.005). Overall, these studies demonstrate the ability of opaganib to induce ICD in tumor cells, which improves the antitumor activity of checkpoint antibodies.

Targeting VCP potentiates immune checkpoint therapy for colorectal cancer

Immune checkpoint blockade therapies are still ineffective for most patients with colorectal cancer (CRC). Immunogenic cell death (ICD) enables the release of key immunostimulatory signals to drive efficient anti-tumor immunity, which could be used to potentiate the effects of immune checkpoint inhibitors. Here, we showed that inhibition of valosin-containing protein (VCP) elicits ICD in CRC. Meanwhile, VCP inhibitor upregulates PD-L1 expression and compromises anti-tumor immunity in vivo. Mechanistically, VCP transcriptionally regulates PD-L1 expression in a JAK1-dependent manner. Combining VCP inhibitor with anti-PD1 remodels tumor immune microenvironment and reduces tumor growth in mouse models of CRC. Addition of oncolytic virus further augments the therapeutic activity of the combination regimen. Our study shows the molecular mechanism for regulating PD-L1 expression by VCP and suggests that inhibition of VCP has the potential to increase the efficacy of immunotherapy in CRC.

Immunotherapies inducing immunogenic cell death in cancer: insight of the innate immune system

Cancer immunotherapies include monoclonal antibodies, cytokines, oncolytic viruses, cellular therapies, and other biological and synthetic immunomodulators. These are traditionally studied for their effect on the immune system's role in eliminating cancer cells. However, some of these therapies have the unique ability to directly induce cytotoxicity in cancer cells by inducing immunogenic cell death (ICD). Unlike general immune stimulation, ICD triggers specific therapy-induced cell death pathways, based on the release of damage-associated molecular patterns (DAMPs) from dying tumour cells. These activate innate pattern recognition receptors (PRRs) and subsequent adaptive immune responses, offering the promise of sustained anticancer drug efficacy and durable antitumour immune memory. Exploring how onco-immunotherapies can trigger ICD, enhances our understanding of their mechanisms and potential for combination strategies. This review explores the complexities of these immunotherapeutic approaches that induce ICD, highlighting their implications for the innate immune system, addressing challenges in cancer treatment, and emphasising the pivotal role of ICD in contemporary cancer research.

Construction of immunogenic cell death-related molecular subtypes and prognostic signature in colorectal cancer

Immunotherapy is a promising treatment for advanced colorectal cancers (CRCs). However, immunotherapy resistance remains a common problem. Immunogenic cell death (ICD), a form of regulated cell death, induces adaptive immunity, thereby enhancing anti-tumor immunity. Research increasingly suggests that inducing ICD is a promising avenue for cancer immunotherapy and identifying ICD-related biomarkers for CRCs would create a new direction for targeted therapies. Thus, this study used bioinformatics to address these questions and create a prognostic signature, aiming to improve individualized CRC treatment. We identified two ICD -related molecular subtypes of CRCs. The high subtype showed pronounced immune cell infiltration, high immune activity, and high expression of human leukocyte antigen and immune checkpoints genes. Subsequently, we constructed and validated a prognostic signature comprising six genes (CD1A, TSLP, CD36, TIMP1, MC1R, and NRG1) using random survival forest analyses. Further analysis using this prediction model indicated that patients with CRCs in the low-risk group exhibited favorable clinical outcomes and better immunotherapy responses than those in the high-risk group. Our findings provide novel insights into determining the prognosis and design of personalized immunotherapeutic strategies for patients with CRCs.

Four Ounces Can Move a Thousand Pounds: The Enormous Value of Nanomaterials in Tumor Immunotherapy

The application of nanomaterials in healthcare has emerged as a promising strategy due to their unique structural diversity, surface properties, and compositional diversity. In particular, nanomaterials have found a significant role in improving drug delivery and inhibiting the growth and metastasis of tumor cells. Moreover, recent studies have highlighted their potential in modulating the tumor microenvironment (TME) and enhancing the activity of immune cells to improve tumor therapy efficacy. Various types of nanomaterials are currently utilized as drug carriers, immunosuppressants, immune activators, immunoassay reagents, and more for tumor immunotherapy. Necessarily, nanomaterials used for tumor immunotherapy can be grouped into two categories: organic and inorganic nanomaterials. Though both have shown the ability to achieve the purpose of tumor immunotherapy, their composition and structural properties result in differences in their mechanisms and modes of action. Organic nanomaterials can be further divided into organic polymers, cell membranes, nanoemulsion-modified, and hydrogel forms. At the same time, inorganic nanomaterials can be broadly classified as nonmetallic and metallic nanomaterials. The current work aims to explore the mechanisms of action of these different types of nanomaterials and their prospects for promoting tumor immunotherapy.

Nano-enabled colorectal cancer therapy

Colorectal cancer (CRC), one of the most common and deadliest diseases worldwide, poses a great health threat and social burden. The clinical treatments of CRC encompassing surgery, chemotherapy, and radiotherapy are challenged with toxicity, therapy resistance, and recurrence. In the past two decades, targeted therapy and immunotherapy have greatly improved the therapeutic benefits of CRC patients but they still suffer from drug resistance and low response rates. Very recently, gut microbiota regulation has exhibited a great potential in preventing and treating CRC, as well as in modulating the efficacy and toxicity of chemotherapy and immunotherapy. In this review, we provide a cutting-edge summary of nanomedicine-based treatment in colorectal cancer, highlighting the recent progress of oral and systemic tumor-targeting and/or tumor-activatable drug delivery systems as well as novel therapeutic strategies against CRC, including nano-sensitizing immunotherapy, anti-inflammation, gut microbiota modulation therapy, etc. Finally, the recent endeavors to address therapy resistance, metastasis, and recurrence in CRC were discussed. We hope this review could offer insight into the design and development of nanomedicines for CRC and beyond.

The construction of a prognostic model of cervical cancer based on four immune-related LncRNAs and an exploration of the correlations between the model and oxidative stress

Introduction: The immune-related lncRNAs (IRLs) are critical for the development of cervical cancer (CC), but it is still unclear how exactly ILRs contribute to CC. In this study, we aimed to examine the relationship between IRL and CC in detail. Methods: First, the RNAseq data and clinical data of CC patients were collected from The Cancer Genome Atlas (TCGA) database, along with the immune genes from the Import database. We used univariate cox and least absolute shrinkage and selection operator (lasso) to obtain IRLs for prediction after screening the variables. According to the expression levels and risk coefficients of IRLs, the riskscore were calculated. We analyzed the relationship between the model and oxidative stress. We stratified the risk model into two as the high and low-risk groups. We also evaluated the survival differences, immune cell differences, immunotherapeutic response differences, and drug sensitivity differences between the risk groups. Finally, the genes in the model were experimentally validated. Results: Based on the above analyses, we further selected four IRLs (TFAP2A.AS1, AP000911.1, AL133215.2, and LINC02078) to construct the risk model. The model was associated with oxidative-stress-related genes, especially SOD2 and OGG1. Patients in the high-risk group had a lower overall survival than those in the low-risk group. Riskscore was positively correlated with resting mast cells, neutrophils, and CD8+ T-cells. Patients in the low-risk group showed a greater sensitivity to immunosuppression therapy. In addition, we found that patients with the PIK3CA mutation were more sensitive to chemotherapeutic agents such as dasatinib, afatinib, dinaciclib and pelitinib. The function of AL133215.2 was verified, which was consistent with previous findings, and AL133215.2 exerted a pro-tumorigenic effect. We also found that AL133215.2 was closely associated with oxidative-stress-related pathways. Discussion: The results suggested that risk modeling might be useful for prognosticating patients with CC and opening up new routes for immunotherapy.

Systematic investigation of chemo-immunotherapy synergism to shift anti-PD-1 resistance in cancer

Chemo-immunotherapy combinations have been regarded as one of the most practical ways to improve immunotherapy response in cancer patients. In this study, we integrated the transcriptomics data from immunotherapy-treated tumors and compound-treated cell lines to systematically identify chemo-immunotherapy synergisms and their underlying mechanisms. Through analyzing anti-PD-1 treatment induced expression changes in patient tumors, we developed a shift ability score that can measure whether a chemotherapy treatment shifts anti-PD-1 response. By applying the shift ability analysis on 41,321 compounds and 16,853 shRNA treated cancer cell line expression profiles, we characterized a systematic landscape of chemo-immunotherapy synergism and prioritized 17 potential synergy targets. Further investigation of the treatment induced transcriptomic data revealed that a mitophagy-dsRNA-MAVS-dependent activation of type I IFN signaling may be a novel mechanism for chemo-immunotherapy synergism. Our study represents the first comprehensive effort to mechanistically characterize chemo-immunotherapy synergism and will facilitate future pre-clinical and clinical studies.

AhR diminishes the efficacy of chemotherapy via suppressing STING dependent type-I interferon in bladder cancer

The induction of type-I interferons (IFN-Is) is important for the efficacy of chemotherapy. By investigating the role of amino acids in regulation of IFN-I production under chemo-drug treatment in bladder cancer (BC) cells, we find an inherent AhR-dependent negative feedback to restrain STING signaling and IFN-I production. Mechanistically, in a ligand dependent manner, AhR bridges STING and CUL4B/RBX1 E3 ligase complex, facilitating STING degradation through ubiquitin-proteasome pathway. Inhibition of AhR increases STING levels and reduces tumor growth under cisplatin or STING agonist treatment. Endogenous AhR ligands are mainly consisted of tryptophan (Trp) metabolites; dietary Trp restriction, blocking the key Trp metabolism rate-limiting enzyme IDO1 or inhibition of cellular Trp importation also show similar effect as AhR inhibition. Clinically, BC patients with higher intratumoral expression of AhR or stronger intratumoral Trp metabolism (higher IDO1 or Kyn levels) that lead to higher AhR activation show worse response rate to neoadjuvant chemotherapy (NAC).

Reinforcing the immunogenic cell death to enhance cancer immunotherapy efficacy

Immunogenic cell death (ICD) has been a revolutionary modality in cancer treatment since it kills primary tumors and prevents recurrent malignancy simultaneously. ICD represents a particular form of cancer cell death accompanied by production of damage-associated molecular patterns (DAMPs) that can be recognized by pattern recognition receptors (PRRs), which enhances infiltration of effector T cells and potentiates antitumor immune responses. Various treatment methods can elicit ICD involving chemo- and radio-therapy, phototherapy and nanotechnology to efficiently convert dead cancer cells into vaccines and trigger the antigen-specific immune responses. Nevertheless, the efficacy of ICD-induced therapies is restrained due to low accumulation in the tumor sites and damage of normal tissues. Thus, researchers have been devoted to overcoming these problems with novel materials and strategies. In this review, current knowledge on different ICD modalities, various ICD inducers, development and application of novel ICD-inducing strategies are summarized. Moreover, the prospects and challenges are briefly outlined to provide reference for future design of novel immunotherapy based on ICD effect.

Promotion of ICD via Nanotechnology

Immunotherapy represents the most promising treatment strategy for cancer, but suffers from compromised therapeutic efficiency due to low immune activity of tumor cells and an immunosuppressive microenvironment, which significantly hampers the clinical translations of this treatment strategy. To promote immunotherapy with desired therapeutic efficiency, immunogenic cell death (ICD), a particular type of death capable of reshaping body's antitumor immune activity, has drawn considerable attention due to the potential to stimulate a potent immune response. Still, the potential of ICD effect remains unsatisfactory because of the intricate tumor microenvironment and multiple drawbacks of the used inducing agents. ICD has been thoroughly reviewed so far with a general classification of ICD as a kind of immunotherapy strategy and repeated discussion of the related mechanism. However, there are no published reviews, to the authors' knowledge, providing a systematic summarization on the enhancement of ICD via nanotechnology. For this purpose, this review first discusses the four stages of ICD according to the development mechanisms, followed by a comprehensive description on the use of nanotechnology to enhance ICD in the corresponding four stages. The challenges of ICD inducers and possible solutions are finally summarized for future ICD-based enhanced immunotherapy.

Identification of immunogenic cell death-related signature on prognosis and immunotherapy in kidney renal clear cell carcinoma

Background

Immunogenic cell death (ICD) is considered a particular cell death modality of regulated cell death (RCD) and plays a significant role in various cancers. The connection between kidney renal clear cell carcinoma (KIRC) and ICD remains to be thoroughly explored.

Methods

We conducted a variety of bioinformatics analyses using R software, including cluster analysis, prognostic analysis, enrichment analysis and immune infiltration analysis. In addition, we performed Quantitative Real-time PCR to evaluate RNA levels of specific ICD genes. The proliferation was measured through Cell Counting Kit-8 (CCK-8) assay and colony-formation assay in RCC cell lines.

Results

We determined two ICD subtypes through consensus clustering analysis. The two subtypes showed significantly different clinical outcomes, genomic alterations and tumor immune microenvironment. Moreover, we constructed the ICD prognostic signature based on TF, FOXP3, LY96, SLC7A11, HSP90AA1, UCN, IFNB1 and TLR3 and calculated the risk score for each patient. Kaplan-Meier survival analysis and ROC curve demonstrated that patients in the high-risk group had significantly poorer prognosis compared with the low-risk group. We then validated the signature through external cohort and further evaluated the relation between the signature and clinical features, tumor immune microenvironment and immunotherapy response. Given its critical role in ICD, we conducted further analysis on LY96. Our results indicated that downregulation of LY96 inhibited the proliferation ability of RCC cells.

Conclusions

Our research revealed the underlying function of ICD in KIRC and screened out a potential biomarker, which provided a novel insight into individualized immunotherapy in KIRC.

Polymer/copper nanocomplex-induced lysosomal cell death promotes tumor lymphocyte infiltration and synergizes anti-PD-L1 immunotherapy for triple-negative breast cancer

Our previous research discovered that combining the PDA-PEG polymer with copper ions can selectively kill cancer cells. However, the precise mechanism by which this combination functions was not fully understood. This study revealed that the PDA-PEG polymer and copper ions form complementary PDA-PEG/copper (Poly/Cu) nanocomplexes by facilitating copper ion uptake and lysosomal escape. An in vitro study found that Poly/Cu killed 4T1 cells through a lysosome cell death pathway. Furthermore, Poly/Cu inhibited both the proteasome function and autophagy pathway and induced immunogenic cell death (ICD) in 4T1 cells. The Poly/Cu induced ICD coupled with the checkpoint blockade effect of the anti-PD-L1 antibody (aPD-L1) synergistically promoted immune cell penetration into the tumor mass. Benefiting from the tumor-targeting effect and cancer cell-selective killing effect of Poly/Cu complexes, the combinatory treatment of aPD-L1 and Poly/Cu effectively suppressed the progression of triple-negative breast cancer without inducing systemic side effects.

In Situ Formed ROS-Responsive Hydrogel with STING Agonist and Gemcitabine to Intensify Immunotherapy against Pancreatic Ductal Adenocarcinoma

Immunotherapy, the most revolutionary anticancer strategy, faces major obstacles in yielding desirable outcomes in pancreatic ductal adenocarcinoma (PDAC) due to the highly immunosuppressive tumor microenvironment (TME). Meanwhile, when used alone, the traditional first-line chemotherapeutic agent gemcitabine (GEM) in PDAC treatment is also insufficient to achieve lasting efficacy. In this study, a reactive oxygen species degradable hydrogel system, denoted as GEM-STING@Gel, is engineered to codeliver gemcitabine and the stimulator of interferon genes (STING) agonist DMXAA (5,6-dimethylxanthenone-4-acetic acid) into the tumor site. In this work, the strategy addresses the major challenges of current immunotherapies with a facile platform, which can synergistically activate innate immunity and promote the cytotoxic T lymphocytes infiltration at the tumor site, thereby modulating the immunosuppressive TME. Further, the efficient therapeutic potency of the immunotherapy is confirmed in an orthotopic postsurgical model, unleashing the translational potential to prevent tumor recurrence after surgical resection. This study underscores the advantages of this integrative strategy that combines chemotherapy, immunotherapy, and biomaterial-based hydrogel, including improved therapeutic efficacy, operational convenience, and superior biosafety.

Carbonic anhydrase IX inhibitor S4 triggers release of DAMPs related to immunogenic cell death in glioma cells via endoplasmic reticulum stress pathway

BACKGROUND

Immunogenic cell death (ICD), which releases danger-associated molecular patterns (DAMP) that induce potent anticancer immune response, has emerged as a key component of therapy-induced anti-tumor immunity. The aim of this work was to analyze whether the carbonic anhydrase IX inhibitor S4 can elicit ICD in glioma cells.

METHODS

The effects of S4 on glioma cell growth were evaluated using the CCK-8, clonogenic and sphere assays. Glioma cell apoptosis was determined by flow cytometry. Surface-exposed calreticulin (CRT) was inspected by confocal imaging. The supernatants of S4-treated cells were concentrated for the determination of HMGB1and HSP70/90 expression by immunoblotting. RNA-seq was performed to compare gene expression profiles between S4-treated and control cells. Pharmacological inhibition of apoptosis, autophagy, necroptosis and endoplasmic reticulum (ER) stress was achieved by inhibitors. In vivo effects of S4 were evaluated in glioma xenografts. Immunohistochemistry (IHC) was performed to stain Ki67 and CRT.

RESULTS

S4 significantly decreased the viability of glioma cells and induced apoptosis and autophagy. Moreover, S4 triggered CRT exposure and the release of HMGB1 and HSP70/90. Inhibition of either apoptosis or autophagy significantly reversed S4-induced release of DAMP molecules. RNA-seq analysis indicated that the ER stress pathway was deregulated upon exposure to S4. Both PERK-eIF2α and IRE1α- XBP1 axes were activated in S4-treated cells. Furthermore, pharmacological inhibition of PERK significantly suppressed S4-triggered ICD markers and autophagy. In glioma xenografts, S4 significantly reduced tumor growth.

CONCLUSIONS

Altogether, these findings suggest S4 as a novel ICD inducer in glioma and might have implications for S4-based immunotherapy. Video Abstract.

Unique vulnerability of RAC1-mutant melanoma to combined inhibition of CDK9 and immune checkpoints

RAC1P29S is the third most prevalent hotspot mutation in sun-exposed melanoma. RAC1 alterations in cancer are correlated with poor prognosis, resistance to standard chemotherapy, and insensitivity to targeted inhibitors. Although RAC1P29S mutations in melanoma and RAC1 alterations in several other cancers are increasingly evident, the RAC1-driven biological mechanisms contributing to tumorigenesis remain unclear. Lack of rigorous signaling analysis has prevented identification of alternative therapeutic targets for RAC1P29S-harboring melanomas. To investigate the RAC1P29S-driven effect on downstream molecular signaling pathways, we generated an inducible RAC1P29S expression melanocytic cell line and performed RNA-sequencing (RNA-seq) coupled with multiplexed kinase inhibitor beads and mass spectrometry (MIBs/MS) to establish enriched pathways from the genomic to proteomic level. Our proteogenomic analysis identified CDK9 as a potential new and specific target in RAC1P29S-mutant melanoma cells. In vitro, CDK9 inhibition impeded the proliferation of in RAC1P29S-mutant melanoma cells and increased surface expression of PD-L1 and MHC Class I proteins. In vivo, combining CDK9 inhibition with anti-PD-1 immune checkpoint blockade significantly inhibited tumor growth only in melanomas that expressed the RAC1P29S mutation. Collectively, these results establish CDK9 as a novel target in RAC1-driven melanoma that can further sensitize the tumor to anti-PD-1 immunotherapy.

Withaferin A Increases the Effectiveness of Immune Checkpoint Blocker for the Treatment of Non-Small Cell Lung Cancer

Treatment of late-stage lung cancers remains challenging with a five-year survival rate of 8%. Immune checkpoint blockers (ICBs) revolutionized the treatment of non-small cell lung cancer (NSCLC) by reactivating anti-tumor immunity. Despite achieving durable responses, ICBs are effective in only 20% of patients due to immune resistance. Therefore, synergistic combinatorial approaches that overcome immune resistance are currently under investigation. Herein, we studied the immunomodulatory role of Withaferin A (WFA)-a herbal compound-and its effectiveness in combination with an ICB for the treatment of NSCLC. Our in vitro results show that WFA induces immunogenic cell death (ICD) in NSCLC cell lines and increases expression of the programmed death ligand-1 (PD-L1). The administration of N-acetyl cysteine (NAC), a reactive oxygen species (ROS) scavenger, abrogated WFA-induced ICD and PD-L1 upregulation, suggesting the involvement of ROS in this process. Further, we found that a combination of WFA and α-PD-L1 significantly reduced tumor growth in an immunocompetent tumor model. Our results showed that WFA increases CD-8 T-cells and reduces immunosuppressive cells infiltrating the tumor microenvironment. Administration of NAC partially inhibited the anti-tumor response of the combination regimen. In conclusion, our results demonstrate that WFA sensitizes NSCLC to α-PD-L1 in part via activation of ROS.

Genomic analysis of immunogenic cell death-related subtypes for predicting prognosis and immunotherapy outcomes in glioblastoma multiforme

Immunogenic cell death (ICD), a unique form of cancer cell death, has therapeutic potential in anti-tumour immunotherapy. The aim of this study is to explore the predictive potential of ICD in the prognosis and immunotherapy outcomes of glioblastoma multiforme (GBM). RNA sequencing data and clinical information were downloaded from three databases. Unsupervised consistency clustering analysis was used to identify ICD-related clusters and gene clusters. Additionally, the ICD scores were determined using principal component analysis and the Boruta algorithm via dimensionality reduction techniques. Subsequently, three ICD-related clusters and three gene clusters with different prognoses were identified, with differences in specific tumour immune infiltration-related lymphocytes in these clusters. Moreover, the ICD score was well differentiated among patients with GBM, and the ICD score was considered an independent prognostic factor for patients with GBM. Furthermore, two datasets were used for the external validation of ICD scores as predictors of prognosis and immunotherapy outcomes. The validation analysis suggested that patients with high ICD scores had a worse prognosis. Additionally, a higher proportion of patients with high ICD scores were non-responsive to immunotherapy. Thus, the ICD score has the potential as a biomarker to predict the prognosis and immunotherapy outcomes of patients with GBM.

Regorafenib induces damage-associated molecular patterns, cancer cell death and immune modulatory effects in a murine triple negative breast cancer model

Damage associated molecular patterns (DAMPs), including calreticulin (CRT) exposure, high-mobility group box 1 protein (HMGB1) elevation, and ATP release, characterize immunogenic cell death (ICD) and may play a role in cancer immunotherapy. Triple negative breast cancer (TNBC) is an immunogenic subtype of breast cancer with higher lymphocyte infiltration. Here, we found that regorafenib, a multi-target angiokinase inhibitor previously known to suppress STAT3 signaling, induced DAMPs and cell death in TNBC cells. Regorafenib induced the expression of HMGB1 and CRT, and the release of ATP. Regorafenib-induced HMGB1 and CRT were attenuated following STAT3 overexpression. In a 4T1 syngeneic murine model, regorafenib treatment increased HMGB1 and CRT expression in xenografts, and effectively suppressed 4T1 tumor growth. Immunohistochemical staining revealed increased CD4⁺ and CD8⁺ tumor-infiltrating T cells in 4T1 xenografts following regorafenib treatment. Regorafenib treatment or programmed death-1 (PD-1) blockade using anti-PD-1 monoclonal antibody reduced lung metastasis of 4T1 cells in immunocompetent mice. While regorafenib increases the proportion of MHC II high expression on dendritic cells in mice with smaller tumors, the combination of regorafenib and PD-1 blockade did not show a synergistic effect on anti-tumor activity. These results suggest that regorafenib induces ICD and suppresses tumor progression in TNBC. It should be carefully evaluated when developing a combination therapy with an anti-PD-1 antibody and a STAT3 inhibitor.

Raddeanin A Enhances Mitochondrial DNA-cGAS/STING Axis-Mediated Antitumor Immunity by Targeting Transactive Responsive DNA-Binding Protein 43

Immune checkpoint therapies (ICT) have achieved unprecedented efficacy in multiple cancer treatments, but are still limited by low clinical response rates. Identification of immunogenic cell death (ICD)-inducing drugs that can induce tumor cell immunogenicity and reprogram the tumor microenvironment is an attractive approach to enhance antitumor immunity. In the present study, Raddeanin A (RA), an oleanane class triterpenoid saponin isolated from Anemone raddeana Regel, is uncovered as a potent ICD inducer through an ICD reporter assay combined with a T cell activation assay. RA significantly increases high-mobility group box 1 release in tumor cells and promotes dendritic cell (DC) maturation and CD8⁺ T cell activation for tumor control. Mechanistically, RA directly binds to transactive responsive DNA-binding protein 43 (TDP-43) and induces TDP-43 localization to mitochondria and mtDNA leakage, leading to cyclic GMP-AMP synthase/stimulator of interferon gene-dependent upregulation of nuclear factor κB and type I interferon signaling, thereby potentiating the DC-mediated antigen cross-presentation and T cell activation. Moreover, combining RA with anti-programmed death 1 antibody effectively enhances the efficacy of ICT in animals. These findings highlight the importance of TDP-43 in ICD drug-induced antitumor immunity and reveal a potential chemo-immunotherapeutic role of RA in enhancing the efficacy of cancer immunotherapy.

Improvement strategy for immune checkpoint blockade: A focus on the combination with immunogenic cell death inducers

Cancer immunotherapies have yielded promising outcomes in various malignant tumors by blocking specific immune checkpoint molecules, such as programmed cell death 1 and cytotoxic T lymphocyte antigen 4. However, only a few patients respond to immune checkpoint blockade therapy because of the poor immunogenicity of tumor cells and immune-suppressive tumor microenvironment. Accumulating evidence suggests that chemotherapeutic agents, including oxaliplatin and doxorubicin, not only mediate direct cytotoxicity in tumor cells but also induce immunogenic cancer cell death to stimulate a powerful anti-cancer immune response in the tumor microenvironment. In this review, we summarize the recent advances in cancer combination therapy based on immune checkpoint inhibitors plus immunogenic cell death inducers. Despite some clinical failures and challenges, immunogenic cell death inducers have displayed great potential when combined with immune checkpoint inhibitors for anti-cancer treatment in both preclinical studies and clinical trials.

Characterization of immune cell populations in syngeneic murine tumor models

Immunocompetent murine models are important tools for preclinical evaluation of immunotherapies. Here, six different immunocompetent tumor models based on four different cell lines were characterized, including metastatic lung cancer (CMT 167), triple-negative breast cancer (4T1), pancreatic cancer (KPCY), and colon cancer (MC38). The tumors were implanted subcutaneously or orthotopically before the animals were treated with anti-PD1 checkpoint inhibitor. A range of innate and adaptive immune cells were then quantified by flow cytometry of single-cell suspensions from the tumors. Furthermore, confocal laser scanning microscopy was used to quantify the density and distribution of T-cells in frozen sections. A model-dependent cellular immune landscape was observed, with variable responsiveness toward anti-PD1, ranging from the most responsive MC38 colon cancer model to the least responsive 4T1 breast cancer model. The study provides an overview of the immune landscape of these tumor models, and a foundation for further elucidation of pro-tumor and anti-tumor mechanisms behind heterogeneous responses towards immunotherapies.

Kinase inhibitors: Opportunities for small molecule anticancer immunotherapies

As the fifth pillar of cancer treatment, immunotherapy has dramatically changed the paradigm of therapeutic strategies by focusing on the host's immune system. In the long road of immunotherapy development, the identification of immune-modulatory effects for kinase inhibitors opened a new chapter in this therapeutic approach. These small molecule inhibitors not only directly eradicate tumors by targeting essential proteins of cell survival and proliferation but can also drive immune responses against malignant cells. This review summarizes the current standings and challenges of kinase inhibitors in immunotherapy, either as a single agent or in a combined modality.

Exploiting RIG-I-like receptor pathway for cancer immunotherapy

RIG-I-like receptors (RLRs) are intracellular pattern recognition receptors that detect viral or bacterial infection and induce host innate immune responses. The RLRs family comprises retinoic acid-inducible gene 1 (RIG-I), melanoma differentiation-associated gene 5 (MDA5) and laboratory of genetics and physiology 2 (LGP2) that have distinctive features. These receptors not only recognize RNA intermediates from viruses and bacteria, but also interact with endogenous RNA such as the mislocalized mitochondrial RNA, the aberrantly reactivated repetitive or transposable elements in the human genome. Evasion of RLRs-mediated immune response may lead to sustained infection, defective host immunity and carcinogenesis. Therapeutic targeting RLRs may not only provoke anti-infection effects, but also induce anticancer immunity or sensitize "immune-cold" tumors to immune checkpoint blockade. In this review, we summarize the current knowledge of RLRs signaling and discuss the rationale for therapeutic targeting RLRs in cancer. We describe how RLRs can be activated by synthetic RNA, oncolytic viruses, viral mimicry and radio-chemotherapy, and how the RNA agonists of RLRs can be systemically delivered in vivo. The integration of RLRs agonism with RNA interference or CAR-T cells provides new dimensions that complement cancer immunotherapy. Moreover, we update the progress of recent clinical trials for cancer therapy involving RLRs activation and immune modulation. Further studies of the mechanisms underlying RLRs signaling will shed new light on the development of cancer therapeutics. Manipulation of RLRs signaling represents an opportunity for clinically relevant cancer therapy. Addressing the challenges in this field will help develop future generations of cancer immunotherapy.

CDK1 bridges NF-κB and β-catenin signaling in response to H. pylori infection in gastric tumorigenesis

Infection with Helicobacter pylori (H. pylori) is the main risk factor for gastric cancer, a leading cause of cancer-related death worldwide. The oncogenic functions of cyclin-dependent kinase 1 (CDK1) are not fully understood in gastric tumorigenesis. Using public datasets, quantitative real-time PCR, western blot, and immunohistochemical (IHC) analyses, we detect high levels of CDK1 in human and mouse gastric tumors. H. pylori infection induces activation of nuclear factor κB (NF-κB) with a significant increase in CDK1 in in vitro and in vivo models (p < 0.01). We confirm active NF-κB binding sites on the CDK1 promoter sequence. CDK1 phosphorylates and inhibits GSK-3β activity through direct binding with subsequent accumulation and activation of β-catenin. CDK1 silencing or pharmacologic inhibition reverses these effects and impairs tumor organoids and spheroid formation. IHC analysis demonstrates a positive correlation between CDK1 and β-catenin. The results demonstrate a mechanistic link between infection, inflammation, and gastric tumorigenesis where CDK1 plays a critical role.

Panobinostat Induced Spatial In Situ Biomarkers Predictive of Anti-PD-1 Efficacy in Mouse Mammary Carcinoma

Immunotherapies, including anti-PD-1 immune checkpoint blocking (ICB) antibodies, have revolutionized the treatment of many solid malignancies. However, their efficacy in breast cancer has been limited to a subset of patients with triple-negative breast cancer, where ICBs are routinely combined with a range of cytotoxic and targeted agents. Reliable biomarkers predictive of the therapeutic response to ICB in breast cancer are critically missing, though a combination response has been associated with immunogenic cell death (ICD). Here, we utilized a recently developed integrated analytical platform, the multiplex implantable microdevice assay (MIMA), to evaluate the presence and spatial cell relations of literature-based candidate markers predictive of ICB efficacy in luminal mouse mammary carcinoma. MIMA integrates (i) an implantable microdevice for the localized delivery of small amounts of drugs inside the tumor bed with (ii) sequential multiplex immunohistochemistry (mIHC) and spatial cell analysis pipelines to rapidly (within days) describe drug mechanisms of action and find predictive biomarkers in complex tumor tissue. We show that the expression of cleaved caspase-3, ICAM-1, neuropilin-1, myeloperoxidase, calreticulin, galectin-3, and PD-L1 were spatially associated with the efficacy of panobinostat, a pan-HDAC inhibitor that was previously shown to induce immunogenic cell death and synergize with anti-PD-1 in breast cancer. PD-L1 by itself, however, was not a reliable predictor. Instead, ICB efficacy was robustly identified through the in situ hotspot detection of galectin-3-positive non-proliferating tumor zones enriched in cell death and infiltrated by anti-tumor cytotoxic neutrophils positive for ICAM-1 and neuropilin-1. Such hotspots can be specifically detected using distance-based cluster analyses. Single-cell measurements of the functional states in the tumor microenvironment suggest that both qualitative and quantitative effects might drive effective therapy responses. Overall, the presented study provides (i) complementary biological knowledge about the earliest cell events of induced anti-tumor immunity in breast cancer, including the emergence of resistant cancer stem cells, and (ii) newly identified biomarkers in form of specific spatial cell associations. The approach used standard cell-type-, IHC-, and FFPE-based techniques, and therefore the identified spatial clustering of in situ biomarkers can be readily integrated into existing clinical or research workflows, including in luminal breast cancer. Since early drug responses were detected, the biomarkers could be especially applicable to window-of-opportunity clinical trials to rapidly discriminate between responding and resistant patients, thus limiting unnecessary treatment-associated toxicities.

Caspase-8 contributes to an immuno-hot microenvironment by promoting phagocytosis via an ecto-calreticulin-dependent mechanism

BACKGROUND

Caspase-8 (Casp8) acts as an initiator in cell apoptosis signaling. However, the role of Casp8 in tuning the tumor immune microenvironment remains controversial due to the complicated crosstalk between immune-tolerogenic apoptotic cell death and immunogenic cell death cascades.

METHODS

The Cancer Genome Atlas (TCGA) and publicly accessible immune checkpoint blockade (ICB)-treated cohorts were used to investigate the clinical relevance of Casp8. A tumor-bearing mouse model was used to characterize changes in the tumor microenvironment and to explore the efficacy of ICB treatment under Casp8 knockout conditions.

RESULTS

By exploring TCGA datasets, we showed that the expression level of Casp8 was associated with an immuno-hot microenvironment across various solid tumor types. Casp8 deficiency leads to decreased CD8⁺ T cell infiltration and resistance to anti-PD-L1 therapy in a mouse model. Mechanistically, Casp8 deficiency or pharmacological disruption results in impaired ecto-calreticulin transition in tumor cells, which in turn hampers antigen presentation in draining lymph nodes. Furthermore, radiotherapy restored sensitivity to anti-PD-L1 treatment via elevated calreticulin surface expression.

CONCLUSIONS

Our data revealed a causative role of Casp8 in modulating the immunogenicity of tumor cells and responsiveness to ICB immunotherapies and proposed radiotherapy as a salvage approach to overcome Casp8 deficiency-mediated ICB resistance.

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.

An Overview of CDK Enzyme Inhibitors in Cancer Therapy

The ability to address the cell cycle in cancer therapy brings up new medication development possibilities. Cyclin-dependent kinases are a group of proteins that control the progression of the cell cycle. The CDK/cyclin complexes are activated when specific CDK sites are phosphorylated. Because of their non-selectivity and severe toxicity, most first-generation CDK inhibitors (also known as pan-CDK inhibitors) have not been authorized for clinical usage. Despite this, significant progress has been made in allowing pan-CDK inhibitors to be employed in clinical settings. Pan-CDK inhibitors' toxicity and side effects have been lowered in recent years because of the introduction of combination therapy techniques. As a result of this, pan-CDK inhibitors have regained a lot of clinical potential as a combination therapy approach. The CDK family members have been introduced in this overview, and their important roles in cell cycle control have been discussed. Then, we have described the current state of CDK inhibitor research, with a focus on inhibitors other than CDK4/6. We have mentioned first-generation pan-CDKIs, flavopiridol and roscovitine, as well as second-generation CDKIs, dinaciclib, P276-00, AT7519, TG02, roniciclib, and RGB-286638, based on their research phases, clinical trials, and cancer targeting. CDKIs are CDK4/6, CDK7, CDK9, and CDK12 inhibitors. Finally, we have looked into the efficacy of CDK inhibitors and PD1/PDL1 antibodies when used together, which could lead to the development of a viable cancer treatment strategy.