DNA Damage and Cancer Immunotherapy: A STING in the Tale

Immune modulation of the liver metastatic colorectal cancer microenvironment via the oral CAPOX-mediated cGAS-STING pathway

We evaluated modulation of the immunosuppressive tumor microenvironment in both local and liver metastatic colorectal cancer (LMCC), focusing on tumor-associated macrophages, which are the predominant immunosuppressive cells in LMCC. We developed an orally administered metronomic chemotherapy regimen, oral CAPOX. This regimen combines capecitabine and a nano-micelle encapsulated, lysine-linked deoxycholate and oxaliplatin complex (OPt/LDC-NM). The treatment effectively modulated immune cells within the tumor microenvironment by activating the cGAS-STING pathway and inducing immunogenic cell death. This therapy modulated immune cells more effectively than did capecitabine monotherapy, the current standard maintenance chemotherapy for colorectal cancer. The macrophage-modifying effect of oral CAPOX was mediated via the cGAS-STING pathway. This is a newly identified mode of immune cell activation induced by metronomic chemotherapy. Moreover, oral CAPOX synergized with anti-PD-1 antibody (αPD-1) to enhance the T-cell-mediated antitumor immune response. In the CT26. CL25 subcutaneous model, combination therapy achieved a 91 % complete response rate with a confirmed memory effect against the tumor. This combination also altered the immunosuppressive tumor microenvironment in LMCC, which αPD-1 monotherapy could not achieve. Oral CAPOX and αPD-1 combination therapy outperformed the maximum tolerated dose for treating LMCC, suggesting metronomic therapy as a promising strategy.

Tumor-derived nanovesicles enhance cancer synergistic chemo-immunotherapy by promoting cGAS/STING pathway activation and immunogenetic cell death

AIMS

Checkpoint blockade immunotherapy is a promising therapeutic modality that has revolutionized cancer treatment; however, the therapy is only effective on a fraction of patients due to the tumor environment. In tumor immunotherapy, the cGAS-STING pathway is a crucial intracellular immune response pathway. Therefore, this study aimed to develop an immunotherapy strategy based on the cGAS-STING pathway.

MATERIALS AND METHODS

The physicochemical properties of the nanoparticles EM@REV@DOX were characterized by TEM, DLS, and WB. Subcutaneous LLC xenograft tumors were used to determine the biodistribution, antitumor efficacy, and immune response. Blood samples and tissues of interest were harvested for hematological analysis and H&E staining.

SIGNIFICANCE

Overall, our designed nanovesicles provide a new perspective on tumor immunotherapy by ICD and cGAS-STING pathway, promoting DCs maturation, macrophage polarization, and activating T cells, offering a meaningful strategy for accelerating the clinical development of immunotherapy.

KEY FINDINGS

EM@REV@DOX accumulated in the tumor site through EPR and homing targeting effect to release REV and DOX, resulting in DNA damage and finally activating the cGAS-STING pathway, thereby promoting DCs maturation, macrophage polarization, and activating T cells. Additionally, EM@REV@DOX increased the production of pro-inflammatory cytokines (e.g., TNF-α and IFN-β). As a result, EM@REV@DOX was effective in treating tumor-bearing mice and prolonged their lifespans. When combined with αPD-L1, EM@REV@DOX significantly inhibited distant tumor growth, extended the survival of mice, and prevented long-term postoperative tumor metastasis, exhibiting great potential in antitumor immunotherapy.

Disruption of DNA-PKcs-mediated cGAS retention on damaged chromatin potentiates DNA damage-inducing agent-induced anti-multiple myeloma activity

BACKGROUND

Targeting DNA damage repair factors, such as DNA-dependent protein kinase catalytic subunit (DNA-PKcs), may offer an opportunity for effective treatment of multiple myeloma (MM). In combination with DNA damage-inducing agents, this strategy has been shown to improve chemotherapies partially via activation of cGAS-STING pathway by an elevated level of cytosolic DNA. However, as cGAS is primarily sequestered by chromatin in the nucleus, it remains unclear how cGAS is released from chromatin and translocated into the cytoplasm upon DNA damage, leading to cGAS-STING activation.

METHODS

We examined the role of DNA-PKcs inhibition on cGAS-STING-mediated MM chemosensitivity by performing mass spectrometry and mechanism study.

RESULTS

Here, we found DNA-PKcs inhibition potentiated DNA damage-inducing agent doxorubicin-induced anti-MM effect by activating cGAS-STING signaling. The cGAS-STING activation in MM cells caused cell death partly via IRF3-NOXA-BAK axis and induced M1 polarization of macrophages. Moreover, this activation was not caused by defective classical non-homologous end joining (c-NHEJ). Instead, upon DNA damage induced by doxorubicin, inhibition of DNA-PKcs promoted cGAS release from cytoplasmic chromatin fragments and increased the amount of cytosolic cGAS and DNA, activating cGAS-STING.

CONCLUSIONS

Inhibition of DNA-PKcs could improve the efficacy of doxorubicin in treatment of MM by de-sequestrating cGAS in damaged chromatin.

Proteasome inhibitors FHND6091 enhance the ability of NK cells to kill tumor cells through multiple mechanisms

The immune system has a strong connection to tumors. When a tumor cell is recognized as an abnormal cell by the immune system, the immune system may initiate an immune response to kill the tumor cell. In this study, RNA sequencing was performed on multiple myeloma (MM) cells treated with the proteasome inhibitor FHND6091. The transcriptional changes induced by FHND6091 in RPMI8226 cells aligned notably with immune response activation and results indicated upregulation of cGAS-STING pathway-related genes in the FHND6091-treated group. In vivo and in vitro experiments had demonstrated that FHND6091 stimulated the immunoreaction of MM cells via activation of the cyclic guanosine monophosphate-adenosine synthase/stimulator of interferon genes (cGAS-STING) pathway. This activation resulted in the generation of type-I interferons and the mobilization of natural killer (NK) cells. Notably, FHND6091 upregulated the levels of calreticulin and the protein ligands UL16-binding protein 2/5/6, MHC class I chain-related A (MICA), and MICB on the surface of MM cells. Subsequently, upon engaging with the surface activation receptors of NK cells, these ligands triggered NK cell activation, leading to the subsequent elimination of tumor cells. Thus, our findings elucidated the mechanism whereby FHND6091 exerted its immunotherapeutic activity as a STING agonist, enhancing the killing ability of NK cells against tumor cells.

Cancer Radiosensitization Nanoagent to Activate cGAS-STING Pathway for Molecular Imaging Guided Synergistic Radio/Chemo/Immunotherapy

Immunotherapy has emerged as an innovative strategy with the potential to improve outcomes in cancer patients. Recent evidence indicates that radiation-induced DNA damage can activate the cyclic-GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway to enhance the antitumor immune response. Even so, only a small fraction of patients currently benefits from radioimmunotherapy due to the radioresistance and the inadequate activation of the cGAS-STING pathway. Herein, this work integrates hafnium oxide (HfO2) nanoparticles (radiosensitizer) and 7-Ethyl-10-hydroxycamptothecin (SN38, chemotherapy drug, STING agonist) into a polydopamine (PDA)-coated core-shell nanoplatform (HfO2@PDA/Fe/SN38) to achieve synergistic chemoradiotherapy and immunotherapy. The co-delivery of HfO2/SN38 greatly enhances radiotherapy efficacy by effectively activating the cGAS-STING pathway, which then triggers dendritic cells maturation and CD8+ T cells recruitment. Consequently, the growth of both primary and abscopal tumors in tumor-bearing mice is efficiently inhibited. Moreover, the HfO2@PDA/Fe/SN38 complexes exhibit favorable magnetic resonance imaging (MRI)/photoacoustic (PA) bimodal molecular imaging properties. In summary, these developed multifunctional complexes have the potential to intensify immune activation to realize simultaneous cancer Radio/Chemo/Immunotherapy for clinical translation.

PD-L1 at the crossroad between RNA metabolism and immunosuppression

Programmed death ligand-1 (PD-L1) is a key component of tumor immunosuppression. The uneven therapeutic results of PD-L1 therapy have stimulated intensive studies to better understand the mechanisms underlying altered PD-L1 expression in cancer cells, and to determine whether, beyond its immune function, PD-L1 might have intracellular functions promoting tumor progression and resistance to treatments. In this Opinion, we focus on paradigmatic examples highlighting the central role of PD-L1 in post-transcriptional regulation, with PD-L1 being both a target and an effector of molecular mechanisms featured prominently in RNA research, such as RNA methylation, phase separation and RNA G-quadruplex structures, in order to highlight vulnerabilities on which future anti-PD-L1 therapies could be built.

Mitotic MTH1 inhibitor TH1579 induces PD-L1 expression and inflammatory response through the cGAS-STING pathway

The mitotic MTH1 inhibitor TH1579 is a dual inhibitor that inhibits mitosis and incorporation of oxidative DNA damage and leads to cancer-specific cell death. The response to immune checkpoint inhibitor (ICI) treatment is often augmented by DNA damaging agents through the cGAS-STING pathway. This study investigates whether TH1579 can improve the efficacy of immune checkpoint blockades through its immunomodulatory properties. Various human and murine cancer cell lines were treated with mitotic MTH1i TH1579, and the expression of PD-L1 and T-cell infiltration-related chemokines was analysed by flow cytometry and real-time qPCR. Syngeneic mouse models were established to examine the combined effect of TH1579 and PD-L1 blockade. In our investigation, we found that TH1579 upregulates PD-L1 expression at both the protein and mRNA levels in human cancer cell lines. However, in murine cell lines, the increase was less pronounced. An in vivo experiment in a syngeneic mouse melanoma model showed that TH1579 treatment significantly increased the efficacy of atezolizumab, an anti-PD-L1 antibody, compared to vehicle or atezolizumab monotherapy. Furthermore, TH1579 exhibited immune-modulatory properties, elevating cytokines such as IFN-β and chemokines including CCL5 and CXCL10, in a cGAS-STING pathway-dependent manner. In conclusion, TH1579 has the potential to improve ICI treatment by modulating immune checkpoint-related proteins and pathways.

A Prognostic Model for Prostate Cancer Patients Based on Two DNA Damage Response Mutation-Related Immune Genes

Background: DNA damage response (DDR) mutation-related genes and composition of immune cells are core factors affecting the effectiveness of immune checkpoint inhibitor therapy. The aim of this study is to combine DDR with immune-related genes to screen the prognostic signature for prostate cancer (PCa). Methods: Gene expression profile and somatic mutation were downloaded from The Cancer Genome Atlas (TCGA). DDR-related genes were obtained from published study. After identification of prognostic-related DDR genes, samples were divided into mutation and nonmutation groups. Differentially expressed genes between these two groups were screened, followed by selection of immune-related DDR genes. Univariate and multivariate Cox analyses were performed to screen genes for constructing prognostic model. Nomogram model was also developed. The expression level of signature was detected by quantitative real-time PCR (qPCR). Results: Two genes (MYBBP1A and PCDHA9) were screened to construct the prognostic model, and it showed good risk prediction of PCa prognosis. Survival analysis showed that patients in high-risk group had worse overall survival than those in low-risk group. Cox analyses indicated that risk score could be used as an independent prognostic factor for PCa. qPCR results indicated that MYBBP1A was upregulated, whereas PCDHA9 was downregulated in PCa cell lines. Conclusions: A prognostic model based on DDR mutation-related genes for PCa was established, which serves as an effective tool for prognostic differentiation in patients with PCa.

Targeting the CXCL12/CXCR4 pathway to reduce radiation treatment side effects

High precision, image-guided radiotherapy (RT) has increased the therapeutic ratio, enabling higher tumor and lower normal tissue doses, leading to improved patient outcomes. Nevertheless, some patients remain at risk of developing serious side effects.In many clinical situations, the radiation tolerance of normal tissues close to the target volume limits the dose that can safely be delivered and thus the potential for tumor control and cure. This is particularly so in patients being re-treated for tumor progression or a second primary tumor within a previous irradiated volume, scenarios that are becoming more frequent in clinical practice.Various normal tissue 'radioprotective' drugs with the potential to reduce side effects have been studied previously. Unfortunately, most have failed to impact clinical practice because of lack of therapeutic efficacy, concern about concurrent tumor protection or excessive drug-related toxicity. This review highlights the evidence indicating that targeting the CXCL12/CXCR4 pathway can mitigate acute and late RT-induced injury and reduce treatment side effects in a manner that overcomes these previous translational challenges. Pre-clinical studies involving a broad range of normal tissues commonly affected in clinical practice, including skin, lung, the gastrointestinal tract and brain, have shown that CXCL12 signalling is upregulated by RT and attracts CXCR4-expressing inflammatory cells that exacerbate acute tissue injury and late fibrosis. These studies also provide convincing evidence that inhibition of CXCL12/CXCR4 signalling during or after RT can reduce or prevent RT side effects, warranting further evaluation in clinical studies. Greater dialogue with the pharmaceutical industry is needed to prioritize the development and availability of CXCL12/CXCR4 inhibitors for future RT studies.

Immunogenic cell death in cancer: targeting necroptosis to induce antitumour immunity

Most metastatic cancers remain incurable due to the emergence of apoptosis-resistant clones, fuelled by intratumour heterogeneity and tumour evolution. To improve treatment, therapies should not only kill cancer cells but also activate the immune system against the tumour to eliminate any residual cancer cells that survive treatment. While current cancer therapies rely heavily on apoptosis - a largely immunologically silent form of cell death - there is growing interest in harnessing immunogenic forms of cell death such as necroptosis. Unlike apoptosis, necroptosis generates second messengers that act on immune cells in the tumour microenvironment, alerting them of danger. This lytic form of cell death optimizes the provision of antigens and adjuvanticity for immune cells, potentially boosting anticancer treatment approaches by combining cellular suicide and immune response approaches. In this Review, we discuss the mechanisms of necroptosis and how it activates antigen-presenting cells, drives cross-priming of CD8+ T cells and induces antitumour immune responses. We also examine the opportunities and potential drawbacks of such strategies for exposing cancer cells to immunological attacks.

STING Membrane Prevents Post-Surgery Tissue Adhesion and Tumor Recurrence of Colorectal Cancer

Surgery is the standard treatment regimen for resectable colorectal cancer (CRC). However, it is very hard to completely remove all cancer cells in clinical practice, leading to the high recurrence rates of the disease. Moreover, the post-surgery tissue adhesion greatly prevents the possibility of reoperation, significantly limiting the long-term surviving of CRC patients. To overcome CRC recurrence and avoid the post-surgery tissue adhesion, this work develops a novel stimulator of interferon genes "STING" membrane based on the coaxial electrospinning technology and hyaluronic acid modification. A reactive oxygen species responsive prodrug of gambogic acid (GB) and a potent STING agonist (CDN) are coloaded in the core-shell structure of the membrane, which endows the loaded drug with sustained and sequential release patterns. The localized delivery of GB and CDN can selectively induce efficient immunogenic cell death of cancer cells and then evoke the systemic anticancer immunity by activating the Cyclic GMP-AMP (cGAMP) synthase/STING pathway. As-designed "STING" membrane not only safely prevents tumor recurrence through the synergistic chemoimmunotherapy but also efficiently avoids the post-surgery tissue adhesion, facilitating the clinical intervention of CRC.

Clinical sequencing defines the somatic and germline mutation landscapes of Chinese HER2-Low Breast Cancer

More than half of the breast cancer initially labeled as human epidermal growth factor receptor 2 (HER2)-negative actually exhibited low HER2 levels (IHC 1+ or IHC 2+/FISH-) and were classified as HER2-low breast cancer. Previous research emphasized the significant biological heterogeneity in HER2-low breast cancer, highlighting the importance of accurately characterizing HER2-low tumors to promote the precise management of antibody‒drug conjugates. In this study, we established a large-scale targeted sequencing cohort (N = 1907) representing Chinese HER2-low breast cancer patients with detailed clinical annotation. Our research findings revealed that HER2-low breast cancer demonstrated distinct clinical pathological characteristics and mutation landscapes compared to HER2-zero group. When compared to HER2-zero tumors, HER2-low tumors exhibited a higher proportion of Luminal B subtypes and better disease-free survival. In hormone receptor (HR)-positive breast cancer, HER2-low group showed a higher frequency of GATA3 somatic mutations, BRCA2 germline mutations, and mutations in the DNA damage repair pathway. In contrast, in HR-negative breast cancer, the HER2-low group displayed a higher frequency of PIK3CA mutations and PI3K pathway alterations. These findings offered valuable insights for the precise targeted treatment of HER2-low breast cancer in different HR statuses.

Multifaceted roles of RNA editing enzyme ADAR1 in innate immunity

Innate immunity must be tightly regulated to enable sensitive pathogen detection while averting autoimmunity triggered by pathogen-like host molecules. A hallmark of viral infection, double-stranded RNAs (dsRNAs) are also abundantly encoded in mammalian genomes, necessitating surveillance mechanisms to distinguish "self" from "nonself." ADAR1, an RNA editing enzyme, has emerged as an essential safeguard against dsRNA-induced autoimmunity. By converting adenosines to inosines (A-to-I) in long dsRNAs, ADAR1 covalently marks endogenous dsRNAs, thereby blocking the activation of the cytoplasmic dsRNA sensor MDA5. Moreover, beyond its editing function, ADAR1 binding to dsRNA impedes the activation of innate immune sensors PKR and ZBP1. Recent landmark studies underscore the utility of silencing ADAR1 for cancer immunotherapy, by exploiting the ADAR1-dependence developed by certain tumors to unleash an antitumor immune response. In this perspective, we summarize the genetic and mechanistic evidence for ADAR1's multipronged role in suppressing dsRNA-mediated autoimmunity and explore the evolving roles of ADAR1 as an immuno-oncology target.

Long-term outcomes of 1-2 cm rectal neuroendocrine tumors after local excision or radical resection: A population-based multicenter study

Objectives

Studies on rectal neuroendocrine tumors (R-NETs) that are 1-2 cm in size are limited, and the optimal treatment for these tumors is not well established.

Methods

Data from patients with primary localized R-NETs 1-2 cm in size were retrospectively collected from 17 large-scale referral medical centers in China. Long-term prognosis, quality of life (QOL), and fecal incontinence were evaluated, and the effects of local excision (LE) or radical resection (RR) were elucidated using propensity score matching (PSM).

Results

A total of 272 patients were included in this study; 233 underwent LE, and the remaining 39 underwent RR. Patients in the LE group showed lower tumor location, fewer postoperative Clavien-Dindo III-V complications, more G1 tumors, and lower tumor stage. There were no significant differences in the relapse-free survival or overall survival (OS) between the LE and RR groups after PSM. Patients in the LE group reported superior physical, role, emotional, social, and cognitive functions, global QOL, and Wexner fecal incontinence scores compared with those in the RR group (all P < 0.050). Eighteen (6.6%) patients had lymph node metastases. Multivariable analysis revealed that tumor location (odds ratio [OR] = 3.19, 95% confidence interval [CI] 1.04-10.07, P = 0.010), neutrophil-to-lymphocyte ratio (NLR) > 1.80 (OR = 4.50, 1.46-15.89, P = 0.012), and T3-T4 (OR = 36.31, 95% CI 7.85-208.62, P < 0.001) were independent risk factor for lymph node metastasis.

Conclusions

R-NETs measuring 1-2 cm generally have a favorable prognosis, and there is no difference in postoperative survival between LE and RR. For patients without lymph node metastasis, LE should be the preferred choice; however, for patients with a higher tumor location, preoperative NLR >1.8 or T3/T4 tumors, RR should be considered.

Co-delivery of doxorubicin and STING agonist cGAMP for enhanced antitumor immunity

Many chemotherapeutic agents can induce immunogenic cell death (ICD), which leads to the release of danger-associated molecular patterns (DAMPs) and tumor-associated antigens. This process promotes dendritic cells (DCs) maturation and cytotoxic T lymphocyte (CTL) infiltration. However, cancer cells can employ diverse mechanisms to evade the host immune system. Recent studies have shown that stimulator of interferon genes (STING) agonists, such as cGAMP, can amplify ICD-triggered immune responses and enhance the infiltration of immune cells into the tumor microenvironment (TME). Building upon these findings, we constructed a doxorubicin (DOX) and cGAMP co-delivery system (DOX/cGAMP@NPs) for melanoma and triple-negative breast cancer (TNBC) therapy. The results demonstrated that DOX could effectively destroy tumors and induce the release of DAMPs by ICD. Furthermore, in orthotopic 4T1 tumors mice model and subcutaneous B16 tumor mice model, cGAMP could promote the maturation of DCs and CD8+ T cell activation and infiltration by inducing the secretion of type I interferons and pro-inflammation cytokine, which amplified the antitumor immune response induced by DOX. This strategy also promoted the depletion of immunosuppressive cells, potentially alleviating the immunosuppressive TME. In conclusion, our study highlights the combination of DOX-induced ICD and the immune-enhancing properties of cGAMP holds significant implications for future research and clinical applications.

STING pathway as a cancer immunotherapy: Progress and challenges in activating anti-tumor immunity

The stimulator of the interferon genes (STING) signaling pathway plays a crucial role in innate immunity by detecting cytoplasmic DNA and initiating antiviral host defense mechanisms. The STING cascade is triggered when the enzyme cyclic GMP-AMP synthase (cGAS) binds cytosolic DNA and synthesizes the secondary messenger cGAMP. cGAMP activates the endoplasmic reticulum adaptor STING, leading to the activation of kinases TBK1 and IRF3 that induce interferon production. Secreted interferons establish an antiviral state in infected and adjacent cells. Beyond infections, aberrant DNA in cancer cells can also activate the STING pathway. Preclinical studies have shown that pharmacological STING agonists like cyclic dinucleotides elicit antitumor immunity when administered intratumorally by provoking innate and adaptive immunity. Combining STING agonists with immune checkpoint inhibitors may improve outcomes by overcoming tumor immunosuppression. First-generation STING agonists encountered challenges like poor pharmacokinetics, limited tumor specificity, and systemic toxicity. The development of the next-generation STING-targeted drugs to realize the full potential of engaging this pathway for cancer treatment can be a solution to overcome the current challenges, but further studies are required to determine optimal applications and combination regimens for the clinic. Notably, the controlled activation of STING is needed to preclude adverse effects. This review explores the mechanisms and effects of STING activation, its role in cancer immunotherapy, and current challenges.

PARP inhibitor plus radiotherapy reshape the immune suppressive microenvironment and potentiate the efficacy of immune checkpoint inhibitors in tumors with IDH1 mutation

Isocitrate dehydrogenase 1 mutant (IDH1mut) tumors respond poorly to immunotherapy, but are more sensitive to chemoradiotherapy and poly (ADP-ribose) polymerase inhibition (PARPi). Accordingly, some efforts have aimed to capitalize on the IDH1 mutation rather than reverse it. Moreover, radiotherapy (RT) and PARPi can stimulate antitumor immunity, raising the possibility of reversing the immunosuppression caused by IDH1 mutation while killing the tumor. To assess this possibility, we treated IDH1mut tumors and cells with RT + PARPi. RT + PARPi showed enhanced efficacy over either modality alone both in vitro and in vivo. RT + PARPi induced more DNA damage and activated the cGAS-STING pathway more. IFNβ, CXCL10, and CCL5 were also more highly expressed at both the mRNA and protein levels. In two different tumor models, RT + PARPi increased infiltration and cytolytic function of CD8+ T cells, with one model also showing increased CD8+T cell proliferation. RT+PARPi also increased PD-L1 expression and enhanced checkpoint inhibition. Knocking out cGAS reversed the increased CD8+ T cell infiltration and the antitumor effect of RT+PARPi. We conclude that RT + PARPi reshapes the IDH1mut tumor immunosuppressive microenvironment, thereby augmenting checkpoint inhibition.

Moving toward improved immune checkpoint immunotherapy for advanced prostate cancer

Human prostate cancer is a heterogenous malignancy that responds poorly to immunotherapy targeting immune checkpoints. The immunosuppressive tumor microenvironment that is typical of human prostate cancer has been the main obstacle to these treatments. The effectiveness of these therapies is also hindered by acquired resistance, leading to slow progress in prostate cancer immunotherapy. Results from the highly anticipated late-stage clinical trials of PD-1/PD-L1 immune checkpoint blockade in patients with advanced prostate cancer have highlighted some of the obstacles to immunotherapy. Despite the setbacks, there is much that has been learned about the mechanisms that drive resistance, and new strategies are being developed and tested. Here, we review the status of immune checkpoint blockade and the immunosuppressive tumor microenvironment and discuss factors contributing to innate and adaptive resistance to immune checkpoint blockade within the context of prostate cancer. We then examine current strategies aiming to overcome these challenges as well as prospects.

Tumor mutational burden for the prediction of PD-(L)1 blockade efficacy in cancer: challenges and opportunities

Tumor mutational burden (TMB) is a biomarker that measures the number of somatic mutations in a tumor's genome. TMB has emerged as a predictor of response to immune checkpoint inhibitors (ICIs) in various cancer types, and several studies have shown that patients with high TMB have better outcomes when treated with programmed death-ligand 1-based therapies. Recently, the Food and Drug Administration has approved TMB as a companion diagnostic for the use of pembrolizumab in solid tumors. However, despite its potential, the use of TMB as a biomarker for immunotherapy efficacy is limited by several factors. Here we review the limitations of TMB in predicting immunotherapy outcomes in patients with cancer and discuss potential strategies to optimize its use in the clinic.

DNA damage response in brain tumors: A Society for Neuro-Oncology consensus review on mechanisms and translational efforts in neuro-oncology

DNA damage response (DDR) mechanisms are critical to maintenance of overall genomic stability, and their dysfunction can contribute to oncogenesis. Significant advances in our understanding of DDR pathways have raised the possibility of developing therapies that exploit these processes. In this expert-driven consensus review, we examine mechanisms of response to DNA damage, progress in development of DDR inhibitors in IDH-wild-type glioblastoma and IDH-mutant gliomas, and other important considerations such as biomarker development, preclinical models, combination therapies, mechanisms of resistance and clinical trial design considerations.

STING is significantly increased in high-grade glioma with high risk of recurrence

In this study, we aimed to comprehensively characterize the potential relationships among the frequently mutated genes, well-known homologous recombination repair (HRR) proteins, and immune proteins in glioma from a clinical perspective. A total of 126 surgical tissues from patients initially diagnosed with glioma were included. The genetic alterations were tested using the targeted next-generation sequencing technique. The expression of HRR proteins, immune proteins, and genetic alteration-related proteins were detected using immunostaining. Integrated analysis showed that ATRX is positively correlated with STING in high-grade glioma (HGG) with wild-type ATRX and IDH1. Then, a relapse predictive risk-scoring model was established using the least absolute shrinkage and selection operator regression algorithms. The scores based on the expression of ATRX and STING significantly predict the recurrence for glioma patients, which further predict the survival for specific subgroups, characterized with high expression of RAD51 and wild-type TERT. Moreover, STING is significantly higher in patients with high relapse risk. Interestingly, STING inhibitors and agonists both suppress the growth of HGG cells, regardless of their STING levels and STING pathway activity, whereas RAD51 inhibitor B02 is found to exclusively sensitize HGG cells with high expression of STING to temozolomide in vitro and in vivo. Overall, findings in the study not only reveal that ATRX is closely correlated with STING to drive the relapse of HGG, but also provide a STING-guided combined strategy to treat patients with aggressive gliomas. Translation of these findings will ultimately improve the outcomes for ATRX and IDH1 genomically stratified subgroups in HGG.

A Trisulfide Bond Containing Biodegradable Polymer Delivering Pt(IV) Prodrugs to Deplete Glutathione and Donate H2S to Boost Chemotherapy and Antitumor Immunity

The clinical application of cisplatin (CisPt) is limited by its dose-dependent toxicity. To overcome this, we developed reduction-responsive nanoparticles (NP(3S)s) for the targeted delivery of a platinum(IV) (Pt(IV)) prodrug to improve efficacy and reduce the toxicity. NP(3S)s could release Pt(II) and hydrogen sulfide (H2S) upon encountering intracellular glutathione, leading to potent anticancer effects. Notably, NP(3S)s induced DNA damage and activated the STING pathway, which is a known promoter for T cell activation. Comparative RNA profiling revealed that NP(3S)s outperformed CisPt in enhancing T cell immunity, antitumor immunity, and oxidative stress pathways. In vivo experiments showed that NP(3S)s accumulated in tumors, promoting CD8+ T cell infiltration and boosting antitumor immunity. Furthermore, NP(3S)s exhibited robust in vivo anticancer efficacy while minimizing the CisPt-induced liver toxicity. Overall, the results indicate NP(3S)s hold great promise for clinical translation due to their low toxicity profile and potent anticancer activity.

Identification and validation of KIF23 as a hypoxia-regulated lactate metabolism-related oncogene in uterine corpus endometrial carcinoma

AIMS

The "Warburg effect" has been developed from the discovery that hypoxia-inducible factor 1α (HIF-1α) could promote the conversion of pyruvate to lactate. However, no studies have linked hypoxia and lactate metabolism to uterine corpus endometrial carcinoma (UCEC).

MAIN METHODS

Sequencing and clinical data of patients with UCEC were extracted from The Cancer Genome Atlas (TCGA) database. Hypoxia-related lactate metabolism genes (HRLGs) were screened using Spearman's correlation analysis. A prognostic signature based on HRLGs was developed using the least absolute shrinkage and selection operator (LASSO) algorithm. A comprehensive analysis was conducted on the molecular features, immune environment, mutation patterns, and response to drugs between different risk groups. In vitro and in vivo experiments were performed to verify the function of KIF23.

KEY FINDINGS

A five HRLG-based prognostic signature was identified. The prognostic outcome was unfavorable for the high-risk subgroup. Observation of increased pathway activities associated with cell proliferation and DNA damage repair was noted in the high-risk subgroup. Additionally, notable correlations were observed between risk score and immune microenvironment, mutational features, and drug responsiveness. Further, we confirmed KIF23 as a novel oncogene in UCEC, whose silencing decreased proliferation and promoted apoptosis of cancer cells. KIF23 knockdown reduced tumor growth in nude mice. We demonstrated that KIF23 was upregulated under hypoxic stress in a HIF-1α dependent manner. Moreover, KIF23 regulated lactate dehydrogenase A expression.

SIGNIFICANCE

The developed HRLG-related signature was associated with prognosis, immune microenvironment, and drug sensitivity in UCEC. We also revealed KIF23 as a hypoxia-regulated lactate metabolism-related oncogene.

Aryl hydrocarbon receptor suppresses STING-mediated type I IFN expression in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is one of the most aggressive types of cancer. Despite decades of intense investigation, treatment options remain limited, and rapid recurrence with distant metastases remains a significant challenge. Cancer cell-intrinsic production of cytokines such as type I interferons (IFN-I) is a known potent modulator of response to therapy in many cancers, including TNBC, and can influence therapeutic outcome. Here, we report that, in TNBC systems, the aryl hydrocarbon receptor (AhR) suppresses IFN-I expression via inhibition of STImulator of Interferon Genes (STING), a key mediator of interferon production. Intratumoral STING activity is essential in mediating the efficacy of PARP inhibitors (PARPi) which are used in the treatment of cancers harboring BRCA1 deficiency. We find that, in TNBC cells, PARPi treatment activates AhR in a BRCA1 deficiency-dependent manner, thus suggesting the presence of a negative feedback loop aimed at modulating PARPi efficacy. Importantly, our results indicate that the combined inhibition of PARP and AhR is superior in elevating IFN-I expression as compared to PARPi-alone. Thus, AhR inhibition may allow for enhanced IFN-I production upon PARPi in BRCA1-deficient breast cancers, most of which are of TNBC origin, and may represent a therapeutically viable strategy to enhance PARPi efficacy.

Radiation Synergizes with IL2/IL15 Stimulation to Enhance Innate Immune Activation and Antitumor Immunity

Ionizing radiation is known to possess immune modulatory properties. However, how radiotherapy (RT) may complement with different types of immunotherapies to boost antitumor responses is unclear. In mice implanted with EO771 syngeneic tumors, NL-201 a stable, highly potent CD25-independent agonist to IL2 and IL15 receptors with enhanced affinity for IL2Rβγ was given with or without RT. Flow analysis and Western blot analysis was performed to determine the mechanisms involved. STING (-/-) and CD11c+ knockout mice were implanted with EO771 tumors to confirm the essential signaling and cell types required to mediate the effects seen. Combination of RT and NL-201 to enhance systemic immunotherapy with an anti-PD-1 checkpoint inhibitor was utilized to determine tumor growth inhibition and survival, along characterization of tumor microenvironment as compared with all other treatment groups. Here, we showed that RT, synergizing with NL-201 produced enhanced antitumor immune responses in murine breast cancer models. When given together, RT and NL-201 enhanced activation of the cytosolic DNA sensor cyclic GMP-AMP synthase-stimulator of IFN genes (cGAS-STING) pathway, resulting in increased type I IFN production in dendritic cells (DC), and consequently greater tumor infiltration and more efficient priming of antigen-specific T cells. The immune stimulatory mechanisms triggered by NL-201 and RT resulted in superior tumor growth inhibition and survival benefit in both localized and metastatic cancers. Our results support further preclinical and clinical investigation of this novel synergism regimen in locally advanced and metastatic settings.

Metal nanoparticles for cancer therapy: Precision targeting of DNA damage

Cancer, a complex and heterogeneous disease, arises from genomic instability. Currently, DNA damage-based cancer treatments, including radiotherapy and chemotherapy, are employed in clinical practice. However, the efficacy and safety of these therapies are constrained by various factors, limiting their ability to meet current clinical demands. Metal nanoparticles present promising avenues for enhancing each critical aspect of DNA damage-based cancer therapy. Their customizable physicochemical properties enable the development of targeted and personalized treatment platforms. In this review, we delve into the design principles and optimization strategies of metal nanoparticles. We shed light on the limitations of DNA damage-based therapy while highlighting the diverse strategies made possible by metal nanoparticles. These encompass targeted drug delivery, inhibition of DNA repair mechanisms, induction of cell death, and the cascading immune response. Moreover, we explore the pivotal role of physicochemical factors such as nanoparticle size, stimuli-responsiveness, and surface modification in shaping metal nanoparticle platforms. Finally, we present insights into the challenges and future directions of metal nanoparticles in advancing DNA damage-based cancer therapy, paving the way for novel treatment paradigms.

Nanomaterial-mediated modulation of the cGAS-STING signaling pathway for enhanced cancer immunotherapy

Despite the current promise of immunotherapy, many cancer patients still suffer from challenges such as poor immune response rates, resulting in unsatisfactory clinical efficacy of existing therapies. There is an urgent need to combine emerging biomedical discoveries and innovations in traditional therapies. Modulation of the cGAS-STING signalling pathway represents an important innate immunotherapy pathway that serves as a crucial DNA sensing mechanism in innate immunity and viral defense. It has attracted increasing attention as an emerging target for cancer therapy. The recent advancements in nanotechnology have led to the significant utilization of nanomaterials in cancer immunotherapy, owing to their exceptional physicochemical properties such as large specific surface area and efficient permeability. Given the rapid development of cancer immunotherapy driven by the cGAS-STING activation, this study reviews the latest research progress in employing nanomaterials to modulate this signaling pathway. Based on the introduction of the main activation mechanisms of cGAS-STING pathway, this review focuses on nanomaterials that mediate the agonists involved and effectively activate this signaling pathway. In addition, combination nanotherapeutics based on the activation of the cGAS-STING signaling pathway are also discussed, including emerging strategies combining nanoformulated agonists with chemotherapy, radiotherapy as well as other immunomodulation in tumor targeting therapy. STATEMENT OF SIGNIFICANCE: Given the rapid development of cancer immunotherapy driven by the cGAS / STING activation, this study reviews the latest research advances in the use of nanomaterials to modulate this signaling pathway. Based on the introduction of key cGAS-STING components and their activation mechanisms, this review focuses on nanomaterials that can mediate the corresponding agonists and effectively activate this signaling pathway. In addition, combination nanotherapies based on the activation of the cGAS-STING signaling pathway are also discussed, including emerging strategies combining nanoformulated agonists with chemotherapy, radiotherapy as well as immunomodulation in cancer therapy,.

Inhibition of Aurora Kinase Induces Endogenous Retroelements to Induce a Type I/III IFN Response via RIG-I

Type I IFN signaling is a crucial component of antiviral immunity that has been linked to promoting the efficacy of some chemotherapeutic drugs. We developed a reporter system in HCT116 cells that detects activation of the endogenous IFI27 locus, an IFN target gene. We screened a library of annotated compounds in these cells and discovered Aurora kinase inhibitors (AURKi) as strong hits. Type I IFN signaling was found to be the most enriched gene signature after AURKi treatment in HCT116, and this signature was also strongly enriched in other colorectal cancer cell lines. The ability of AURKi to activate IFN in HCT116 was dependent on MAVS and RIG-I, but independent of STING, whose signaling is deficient in these cells. MAVS dependence was recapitulated in other colorectal cancer lines with STING pathway deficiency, whereas in cells with intact STING signaling, the STING pathway was required for IFN induction by AURKi. AURKis were found to induce expression of endogenous retroviruses (ERV). These ERVs were distinct from those induced by the DNA methyltransferase inhibitors (DNMTi), which can induce IFN signaling via ERV induction, suggesting a novel mechanism of action. The antitumor effect of alisertib in mice was accompanied by an induction of IFN expression in HCT116 or CT26 tumors. CT26 tumor growth inhibition by alisertib was absent in NSG mice versus wildtype (WT) mice, and tumors from WT mice with alisertib treatment showed increased in CD8+ T-cell infiltration, suggesting that antitumor efficacy of AURKi depends, at least in part, on an intact immune response.

SIGNIFICANCE

Some cancers deactivate STING signaling to avoid consequences of DNA damage from aberrant cell division. The surprising activation of MAVS/RIG-I signaling by AURKi might represent a vulnerability in STING signaling deficient cancers.

SMARCAL1 is a dual regulator of innate immune signaling and PD-L1 expression that promotes tumor immune evasion

Genomic instability can trigger cancer-intrinsic innate immune responses that promote tumor rejection. However, cancer cells often evade these responses by overexpressing immune checkpoint regulators, such as PD-L1. Here, we identify the SNF2-family DNA translocase SMARCAL1 as a factor that favors tumor immune evasion by a dual mechanism involving both the suppression of innate immune signaling and the induction of PD-L1-mediated immune checkpoint responses. Mechanistically, SMARCAL1 limits endogenous DNA damage, thereby suppressing cGAS-STING-dependent signaling during cancer cell growth. Simultaneously, it cooperates with the AP-1 family member JUN to maintain chromatin accessibility at a PD-L1 transcriptional regulatory element, thereby promoting PD-L1 expression in cancer cells. SMARCAL1 loss hinders the ability of tumor cells to induce PD-L1 in response to genomic instability, enhances anti-tumor immune responses and sensitizes tumors to immune checkpoint blockade in a mouse melanoma model. Collectively, these studies uncover SMARCAL1 as a promising target for cancer immunotherapy.

PARP1 roles in DNA repair and DNA replication: The basi(c)s of PARP inhibitor efficacy and resistance

Genome integrity is under constant insult from endogenous and exogenous sources. In order to cope, eukaryotic cells have evolved an elaborate network of DNA repair that can deal with diverse lesion types and exhibits considerable functional redundancy. PARP1 is a major sensor of DNA breaks with established and putative roles in a number of pathways within the DNA repair network, including repair of single- and double-strand breaks as well as protection of the DNA replication fork. Importantly, PARP1 is the major target of small-molecule PARP inhibitors (PARPi), which are employed in the treatment of homologous recombination (HR)-deficient tumors, as the latter are particularly susceptible to the accumulation of DNA damage due to an inability to efficiently repair highly toxic double-strand DNA breaks. The clinical success of PARPi has fostered extensive research into PARP biology, which has shed light on the involvement of PARP1 in various genomic transactions. A major goal within the field has been to understand the relationship between catalytic inhibition and PARP1 trapping. The specific consequences of inhibition and trapping on genomic stability as a basis for the cytotoxicity of PARP inhibitors remain a matter of debate. Finally, PARP inhibition is increasingly recognized for its capacity to elicit/modulate anti-tumor immunity. The clinical potential of PARP inhibition is, however, hindered by the development of resistance. Hence, extensive efforts are invested in identifying factors that promote resistance or sensitize cells to PARPi. The current review provides a summary of advances in our understanding of PARP1 biology, the mechanistic nature, and molecular consequences of PARP inhibition, as well as the mechanisms that give rise to PARPi resistance.

Mechanism of action and treatment of type I interferon in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) caused by HBV, HCV infection, and other factors is one of the most common malignancies in the world. Although, percutaneous treatments such as surgery, ethanol injection, radiofrequency ablation, and transcatheter treatments such as arterial chemoembolization are useful for local tumor control, they are not sufficient to improve the prognosis of patients with HCC. External interferon agents that induce interferon-related genes or type I interferon in combination with other drugs can reduce the recurrence rate and improve survival in HCC patients after surgery. Therefore, in this review, we focus on recent advances in the mechanism of action of type I interferons, emerging therapies, and potential therapeutic strategies for the treatment of HCC using IFNs.

Integrative analysis of single-cell and bulk RNA-sequencing data revealed T cell marker genes based molecular sub-types and a prognostic signature in lung adenocarcinoma

Immunotherapy has emerged as a promising modality for addressing advanced or conventionally drug-resistant malignancies. When it comes to lung adenocarcinoma (LUAD), T cells have demonstrated significant influence on both antitumor activity and the tumor microenvironment. However, their specific contributions remain largely unexplored. This investigation aimed to delineate molecular subtypes and prognostic indicators founded on T cell marker genes, thereby shedding light on the significance of T cells in LUAD prognosis and precision treatment. The cellular phenotypes were identified by scrutinizing the single-cell data obtained from the GEO repository. Subsequently, T cell marker genes derived from single-cell sequencing analyses were integrated with differentially expressed genes from the TCGA repository to pinpoint T cell-associated genes. Utilizing Cox analysis, molecular subtypes and prognostic signatures were established and subsequently verified using the GEO dataset. The ensuing molecular and immunological distinctions, along with therapy sensitivity between the two sub-cohorts, were examined via the ESTIMATE, CIBERSORT, and ssGSEA methodologies. Compartmentalization, somatic mutation, nomogram development, chemotherapy sensitivity prediction, and potential drug prediction analyses were also conducted according to the risk signature. Additionally, real-time qPCR and the HPA database corroborated the mRNA and protein expression patterns of signature genes in LUAD tissues. In summary, this research yielded an innovative T cell marker gene-based signature with remarkable potential to prognosis and anticipate immunotherapeutic outcomes in LUAD patients.

Nanovaccines: An effective therapeutic approach for cancer therapy

Cancer vaccines hold considerable promise for the immunotherapy of solid tumors. Nanomedicine offers several strategies for enhancing vaccine effectiveness. In particular, molecular or (sub) cellular vaccines can be delivered to the target lymphoid tissues and cells by nanocarriers and nanoplatforms to increase the potency and durability of antitumor immunity and minimize negative side effects. Nanovaccines use nanoparticles (NPs) as carriers and/or adjuvants, offering the advantages of optimal nanoscale size, high stability, ample antigen loading, high immunogenicity, tunable antigen presentation, increased retention in lymph nodes, and immunity promotion. To induce antitumor immunity, cancer vaccines rely on tumor antigens, which are administered in the form of entire cells, peptides, nucleic acids, extracellular vesicles (EVs), or cell membrane-encapsulated NPs. Ideal cancer vaccines stimulate both humoral and cellular immunity while overcoming tumor-induced immune suppression. Herein, we review the key properties of nanovaccines for cancer immunotherapy and highlight the recent advances in their development based on the structure and composition of various (including synthetic and semi (biogenic) nanocarriers. Moreover, we discuss tumor cell-derived vaccines (including those based on whole-tumor-cell components, EVs, cell membrane-encapsulated NPs, and hybrid membrane-coated NPs), nanovaccine action mechanisms, and the challenges of immunocancer therapy and their translation to clinical applications.

Targeting DNA Damage and Repair Machinery via Delivering WEE1 Inhibitor and Platinum (IV) Prodrugs to Stimulate STING Pathway for Maximizing Chemo-Immunotherapy in Bladder Cancer

Both cisplatin-based chemotherapy and immune checkpoint blockers (ICBs)-based immunotherapy are the first-line treatments for patients with advanced bladder cancer. Cancer cells can develop resistance to cisplatin through extensive DNA repair, while a low response rate to ICBs is mostly due to the presence of an immunosuppressive microenvironment and low PD-L1 expression. Herein, a glutathione (GSH)-responsive nanoparticle (NP2) loaded with cisplatin prodrug (Pt (IV)) and WEE1 inhibitor (MK1775) is designed. NP2 can be triggered by GSH in cancer cells, and the released MK1775 can inhibit the activity of WEE1 protein, which ultimately increases DNA damage by cisplatin. Genome-wide RNA sequencing first reveals that NP2 can inhibit DNA repair machinery by interfering with the cell cycle and significantly activate the stimulator of interferon genes pathway. Tumor growth is significantly inhibited by NP2 in vivo. As innate and adaptive immune responses are stimulated, the immunosuppressive microenvironment is modified, and the "immune cold tumor" is transformed into an "immune hot tumor". In addition, NP2 can upregulate PD-L1 expression in tumor cells, thereby increasing the response rate of PD-L1 monoclonal antibody (αPD-L1) and eliciting long-term immune responses in both primary and metastatic tumors.

Inhibition of ACLY overcomes cancer immunotherapy resistance via polyunsaturated fatty acids peroxidation and cGAS-STING activation

Adenosine 5'-triphosphate citrate lyase (ACLY) is a cytosolic enzyme that converts citrate into acetyl-coenzyme A for fatty acid and cholesterol biosynthesis. ACLY is up-regulated or activated in many cancers, and targeting ACLY by inhibitors holds promise as potential cancer therapy. However, the role of ACLY in cancer immunity regulation remains poorly understood. Here, we show that ACLY inhibition up-regulates PD-L1 immune checkpoint expression in cancer cells and induces T cell dysfunction to drive immunosuppression and compromise its antitumor effect in immunocompetent mice. Mechanistically, ACLY inhibition causes polyunsaturated fatty acid (PUFA) peroxidation and mitochondrial damage, which triggers mitochondrial DNA leakage to activate the cGAS-STING innate immune pathway. Pharmacological and genetic inhibition of ACLY overcomes cancer resistance to anti-PD-L1 therapy in a cGAS-dependent manner. Furthermore, dietary PUFA supplementation mirrors the enhanced efficacy of PD-L1 blockade by ACLY inhibition. These findings reveal an immunomodulatory role of ACLY and provide combinatorial strategies to overcome immunotherapy resistance in tumors.

Programmed initiation and enhancement of cGAS/STING pathway for tumour immunotherapy via tailor-designed ZnFe2O4-based nanosystem

The cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)/stimulator of interferon genes (STING) signalling pathway has been a promising target for anticancer immunity, but rationally activating and enhancing this pathway in tumour cells is critical. Herein, a glutathione sensitive ZnFe2O4-based nanosystem is developed to programmatically initiate and enhance the STING signalling pathway in tumour cells. The prepared ZnFe2O4 nanoparticles were coated with cancer cell membrane (CCM), which enabled the nanosystem target tumour cells. In tumour cells, ZnFe2O4 nanoparticles could be disintegrated by responding to high level glutathione, and the released Fe3+ generated reactive oxygen species to induce the DNA leakage into the cytoplasm to stimulate cGAS. Then Zn2+ promoted cGAS-DNA phase separation to intensify the cGAS enzymatic activity. In addition, the low dose encapsulation of paclitaxel (PTX) acting as an antimitotic agent (ZnFe2O4-PTX@CCM) ensured the sustained activation of cGAS/STING pathway. The in vitro and in vivo results confirmed that ZnFe2O4-PTX@CCM elevated the cGAS/STING activity, promoted dendritic cell maturation, increased cytotoxic T lymphocyte and natural killer cells infiltration, eventually inhibiting the tumour progress and postoperative recurrence. This study provided feasible references on constructing STING activation nanosystem for tumour immunotherapy.

Inhibitors of phosphoinositide 3-kinase (PI3K) and phosphoinositide 3-kinase-related protein kinase family (PIKK)

Phosphoinositide 3-kinases (PI3K) and phosphoinositide 3-kinase-related protein kinases (PIKK) are two structurally related families of kinases that play vital roles in cell growth and DNA damage repair. Dysfunction of PIKK members and aberrant stimulation of the PI3K/AKT/mTOR signalling pathway are linked to a plethora of diseases including cancer. In recent decades, numerous inhibitors related to the PI3K/AKT/mTOR signalling have made great strides in cancer treatment, like copanlisib and sirolimus. Notably, most of the PIKK inhibitors (such as VX-970 and M3814) related to DNA damage response have also shown good efficacy in clinical trials. However, these drugs still require a suitable combination therapy to overcome drug resistance or improve antitumor activity. Based on the aforementioned facts, we summarised the efficacy of PIKK, PI3K, and AKT inhibitors in the therapy of human malignancies and the resistance mechanisms of targeted therapy, in order to provide deeper insights into cancer treatment.

Crosstalk between immune checkpoint and DNA damage response inhibitors for radiosensitization of tumors

PURPOSE

This review article is intended to provide a perspective overview of potential strategies to overcome radiation resistance of tumors through the combined use of immune checkpoint and DNA repair inhibitors.

METHODS

A literature search was conducted in PubMed using the terms ("DNA repair* and DNA damage response* and intracellular immune response* and immune checkpoint inhibition* and radio*") until January 31, 2023. Articles were manually selected based on their relevance to the topics analyzed.

RESULTS

Modern radiotherapy offers a wide range of options for tumor treatment. Radiation-resistant subpopulations of the tumor pose a particular challenge for complete cure. This is due to the enhanced activation of molecular defense mechanisms that prevent cell death because of DNA damage. Novel approaches to enhance tumor cure are provided by immune checkpoint inhibitors, but their effectiveness, especially in tumors without increased mutational burden, also remains limited. Combining inhibitors of both immune checkpoints and DNA damage response with radiation may be an attractive option to augment existing therapies and is the subject of the data summarized here.

CONCLUSION

The combination of tested inhibitors of DNA damage and immune responses in preclinical models opens additional attractive options for the radiosensitization of tumors and represents a promising application for future therapeutic approaches.

Types of DNA damage and research progress

DNA damage is a modification in the structure of DNA under the influence of endogenous or exogenous factors. DNA damage can cause different types of diseases and is closely related to genetic mutations, cancer, and aging. The cause of the corresponding reaction process is essential for the study of related cancers and other genetically related diseases. Therefore, it is essential to gain a deeper understanding of the various types of DNA damage. This paper provides a comprehensive review of recent advances in the types of DNA damage and associated reaction processes, including damage to DNA bases, nucleotides, and strands, as well as the biological implications of the damage.

Effector memory T cells induce innate inflammation by triggering DNA damage and a non-canonical STING pathway in dendritic cells

Cognate interaction between CD4+ effector memory T (TEM) cells and dendritic cells (DCs) induces innate inflammatory cytokine production, resulting in detrimental autoimmune pathology and cytokine storms. While TEM cells use tumor necrosis factor (TNF) superfamily ligands to activate DCs, whether TEM cells prompt other DC-intrinsic changes that influence the innate inflammatory response has never been investigated. We report the surprising discovery that TEM cells trigger double-strand DNA breaks via mitochondrial reactive oxygen species (ROS) production in interacting DCs. Initiation of the DNA damage response in DCs induces activation of a cyclic guanosine monophosphate (GMP)-AMP synthase (cGAS)-independent, non-canonical stimulator of interferon genes (STING)-TNF receptor-associated factor 6 (TRAF6)-nuclear factor κB (NF-κB) signaling axis. Consequently, STING-deficient DCs display reduced NF-κB activation and subsequent defects in transcriptional induction and functional production of interleukin-1β (IL-1β) and IL-6 following their interaction with TEM cells. The discovery of TEM cell-induced innate inflammation through DNA damage and a non-canonical STING-NF-κB pathway presents this pathway as a potential target to alleviate T cell-driven inflammation in autoimmunity and cytokine storms.

STING in tumors: a focus on non-innate immune pathways

Cyclic GMP-AMP synthase (cGAS) and downstream stimulator of interferon genes (STING) are involved in mediating innate immunity by promoting the release of interferon and other inflammatory factors. Mitochondrial DNA (mtDNA) with a double-stranded structure has greater efficiency and sensitivity in being detected by DNA sensors and thus has an important role in the activation of the cGAS-STING pathway. Many previous findings suggest that the cGAS-STING pathway-mediated innate immune regulation is the most important aspect affecting tumor survival, not only in its anti-tumor role but also in shaping the immunosuppressive tumor microenvironment (TME) through a variety of pathways. However, recent studies have shown that STING regulation of non-immune pathways is equally profound and also involved in tumor cell progression. In this paper, we will focus on the non-innate immune system pathways, in which the cGAS-STING pathway also plays an important role in cancer.

Lenvatinib activates anti-tumor immunity by suppressing immunoinhibitory infiltrates in the tumor microenvironment of advanced hepatocellular carcinoma

BACKGROUND

Lenvatinib, a multiple receptor tyrosine kinase inhibitor, might exert antitumor effects via tumor immune modulation. However, changes in the tumor immune microenvironment induced by lenvatinib are poorly understood. We investigated the effect of lenvatinib on immune features in clinical samples from patients with hepatocellular carcinoma.

METHODS

Fifty-one patients with advanced hepatocellular carcinoma who received lenvatinib monotherapy as first-line treatment were enrolled. We collected blood sample (n = 51) and tumor tissue (n, baseline/four weeks after treatment initiation/post-progression = 50/8/12). DNA, RNA, and proteins extracted from the tissues were subjected to multi-omics analysis, and patients were classified into two groups according to baseline immune status. Each group was investigated in terms of the dynamics of tumor signaling. We also longitudinally analyzed circulating immune proteins and chemokines in peripheral blood.

RESULTS

Here we show that lenvatinib has similar anti-tumor efficacy with objective response rate and progression-free survival in both Immune-Hot and Immune-Cold subtypes. Immune signatures associated with T-cell functions and interferon responses are enriched in the early phase of treatment, while signatures associated with immunoinhibitory cells are downregulated along with efficient vascular endothelial growth factor receptor and fibroblast growth factor receptor blockades. These findings are supported by imaging mass cytometry, T-cell receptor repertoire analysis and kinetics of circulating proteins. We also identify interleukin-8 and angiopoietin-2 as possible targets of intervention to overcome resistance to existing immunotherapies.

CONCLUSIONS

Our findings show the ability of lenvatinib to modulate tumor immunity in clinical samples of hepatocellular carcinoma.

Development and validation of a novel DNA damage repair-related long non-coding RNA signature in predicting prognosis, immunity, and drug sensitivity in uterine corpus endometrial carcinoma

Background

DNA damage response (DDR) confer resistance to chemoradiotherapy in cancer cells. However, the role of DDR-related lncRNAs (DRLs) in uterine corpus endometrial carcinoma (UCEC) is poorly understood. In this study, we aimed to identify a DRL-related prognostic signature that could guide the clinical treatment of UCEC.

Methods

We extracted transcriptome and clinical data of patients with UCEC from The Cancer Genome Atlas (TCGA) database and identified DRLs using Spearman correlation analysis. Univariate and multivariate Cox analyses were used to determine candidate prognostic DRLs. The samples were randomly divided into training and test cohorts in a 1:1 ratio. A DRL-related risk signature was constructed from the training cohort data using the least absolute shrinkage and selection operator (LASSO) algorithm, and validated using the test and entire cohorts. Subsequently, a prognostic nomogram was developed using a multivariate Cox regression analysis. The functional annotation, immune microenvironment, tumor mutation burden (TMB), immune checkpoint blockade (ICB) efficacy, and drug sensitivity were also comprehensively analyzed between different risk groups. Finally, the function of AC019069.1 was validated in vitro.

Results

A novel risk signature was developed based on nine DRLs. The risk score efficiently predicted the prognosis of patients with UCEC. Based on the median risk score, two subgroups were identified. The DDR-related pathways were upregulated in the high-risk group. Additionally, high-risk patients have low immune activity, poor response to ICB, and weak sensitivity to chemotherapeutic agents, possibly because of the proficient DDR system. Finally, we demonstrated AC019069.1 could promote cell proliferation, decrease apoptosis and maintain genome stability of UCEC cells.

Conclusions

The developed DRL-related signature can predict the prognosis, immune microenvironment, immunotherapy, and chemoradiotherapy responsiveness of UCEC. Our study also revealed the potential value of DDR-targeted therapy in treating high-risk patients with UCEC.

DNA damage induced by CDK4 and CDK6 blockade triggers anti-tumor immune responses through cGAS-STING pathway

CDK4/6 are important regulators of cell cycle and their inhibitors have been approved as anti-cancer drugs. Here, we report a STING-dependent anti-tumor immune mechanism responsible for tumor suppression by CDK4/6 blockade. Clinical datasets show that in human tissues, CDK4 and CDK6 are over-expressed and their expressions are negatively correlated with patients' overall survival and T cell infiltration. Deletion of Cdk4 or Cdk6 in tumor cells significantly reduce tumor growth. Mechanistically, we find that Cdk4 or Cdk6 deficiency contributes to an increased level of endogenous DNA damage, which triggers the cGAS-STING signaling pathway to activate type I interferon response. Knockout of Sting is sufficient to reverse and partially reverse the anti-tumor effect of Cdk4 and Cdk6 deficiency respectively. Therefore, our findings suggest that CDK4/6 inhibitors may enhance anti-tumor immunity through the STING-dependent type I interferon response.

Multifunctional Nanoassembly for MRI-Trackable Dendritic Cell Dependent and Independent Photoimmunotherapy

Immunotherapy has emerged as a triumph in the treatment of malignant cancers. Nevertheless, current immunotherapeutics are insufficient in addressing tumors characterized by tumor cells' inadequate antigenicity and the tumor microenvironment's low immunogenicity (TME). Herein, we developed a novel multifunctional nanoassembly termed FMMC through the self-assembly of indoleamine 2,3-dioxygenase 1 (IDO-1) inhibitor 1-methyl-tryptophan prodrug (FM), Ce6, and ionic manganese (Mn2+) via noncovalent interactions. The laser-ignited FMMC treatment could induce effective immunogenic cell death and activate the STING/MHC-I signaling pathway, thus deeply sculpting the tumor-intrinsic antigenicity to achieve dendritic cell (DC)-dependent and -independent T cell responses against tumors. Meanwhile, by inhibiting IDO-1, FMMC could lead to immunosuppressive TME reversion to an immunoactivated one. FMMC-based phototherapy led to the up-regulation of programmed death-ligand 1 (PD-L1), enhancing the sensitivity of tumors to anti-PD-1 therapy. Furthermore, the incorporation of Mn2+ into FMMC resulted in an augmented longitudinal relaxivity and enhanced the MRI for monitoring the growth of primary tumors and lung metastases. Collectively, the superior reprogramming performance of immunosuppressive tumor cells and TME, combined with excellent anticancer efficacy and MRI capability, made FMMC a promising immune nanosculptor for cancer theranostics.

Efficacy of Frontline Chemotherapy for Extranodal Natural Killer/T-Cell Lymphoma: A Systematic Review and Network Meta-Analysis

Background

Treatment with non-anthracycline (ANT)-based chemotherapy has increased survival in patients with extranodal natural killer/T-cell lymphoma (ENKTCL). However, the relative efficacy of various drug combinations has been contentious. We aimed to identify the most effective chemotherapy regimens for newly diagnosed ENKTCL.

Methods

A network meta-analysis was performed to evaluate the differences in survival and treatment responses across various regimens. The primary objective was overall survival (OS), while secondary outcomes included progression-free survival (PFS), objective response rate (ORR), and complete response (CR). We utilized a Bayesian framework to perform the network meta-analysis. Rank probabilities were assessed by the surface under the cumulative ranking curve (SUCRA). Node-splitting method was used to assess the inconsistency.

Results

A total of 1,113 patients were enrolled across 10 studies. Chemotherapy regimens were grouped into five modalities, for which six types of direct comparisons were available. We identified the asparaginase (ASP)/gemcitabine (GEM)-based regimens superiority over ANT-based, non-ASP/ANT-based and ASP/methotrexate (MTX)-based regimens on OS. Although no significant differences were observed compared with ASP/not otherwise specified-based, ASP/GEM-based regimens were still the best option chemotherapy for OS. Moreover, the ASP/GEM-based regimens demonstrated advantages in PFS, ORR and CR.

Conclusions

According to our network meta-analysis, it appears that ASP/GEM-based regimens could potentially serve as the most effective frontline chemotherapy option for ENKTCL.

Targeting the loss of cGAS/STING signaling in cancer

The cGAS/STING pathway provides a key host defense mechanism by detecting the accumulation of cytoplasmic double-stranded DNA (dsDNA) and mediating innate and adaptive immune signaling. In addition to detecting pathogen-derived dsDNA, cGAS senses intrinsic dsDNA, such as those associated with defective cell cycle progression and mitophagy that has leaked from the nucleus or mitochondria, and subsequently evokes host immunity to eliminate pathogenic cells. In cancer cells, dysregulation of DNA repair and cell cycle caused at the DNA replication checkpoint and spindle assembly checkpoint results in aberrant cytoplasmic dsDNA accumulation, stimulating anti-tumor immunity. Therefore, the suppression of cGAS/STING signaling is beneficial for survival and frequently observed in cancer cells as a way to evade detection by the immune system, and is likely to be related to immune checkpoint blockade (ICB) resistance. Indeed, the mechanisms of ICB resistance overlap with those acquired in cancers during immunoediting to evade immune surveillance. This review highlights the current understanding of cGAS/STING suppression in cancer cells and discusses how to establish effective strategies to regenerate effective anti-tumor immunity through reactivation of the cGAS/STING pathway.

NR1D1 Stimulates Antitumor Immune Responses in Breast Cancer by Activating cGAS-STING Signaling

Potentiating antitumor immunity is a promising therapeutic approach for treating a variety of cancers, including breast cancer. One potential strategy to promote antitumor immunity is targeting DNA damage response. Given that the nuclear receptor NR1D1 (also known as REV-ERBα) inhibits DNA repair in breast cancer cells, we explored the role of NR1D1 in antitumor CD8+ T-cell responses. First, deletion of Nr1d1 in MMTV-PyMT transgenic mice resulted in increased tumor growth and lung metastasis. Orthotopic allograft experiments suggested that loss of Nr1d1 in tumor cells rather than in stromal cells played a prominent role in increasing tumor progression. Comprehensive transcriptome analyses revealed that biological processes including type I IFN signaling and T cell-mediated immune responses were associated with NR1D1. Indeed, the expression of type I IFNs and infiltration of CD8+ T cells and natural killer cells in tumors were suppressed in Nr1d1-/-;MMTV-PyMT mice. Mechanistically, NR1D1 promoted DNA damage-induced accumulation of cytosolic DNA fragments and activated cGAS-STING signaling, which increased the production of type I IFNs and downstream chemokines CCL5 and CXCL10. Pharmacologic activation of NR1D1 by its ligand, SR9009, enhanced type I IFN-mediated antitumor immunity accompanied by the suppression of tumor progression and lung metastasis. Taken together, these findings reveal the critical role of NR1D1 in enhancing antitumor CD8+ T-cell responses, suggesting that NR1D1 may be a good therapeutic target for breast cancer.

SIGNIFICANCE

NR1D1 suppresses breast cancer progression and lung metastasis by enhancing antitumor immunity via cGAS-STING pathway activation, which provides potential immunotherapeutic strategies for breast cancer.

Targeting DNA Damage Repair and Immune Checkpoint Proteins for Optimizing the Treatment of Endometrial Cancer

The dependence of cancer cells on the DNA damage response (DDR) pathway for the repair of endogenous- or exogenous-factor-induced DNA damage has been extensively studied in various cancer types, including endometrial cancer (EC). Targeting one or more DNA damage repair protein with small molecules has shown encouraging treatment efficacy in preclinical and clinical models. However, the genes coding for DDR factors are rarely mutated in EC, limiting the utility of DDR inhibitors in this disease. In the current review, we recapitulate the functional role of the DNA repair system in the development and progression of cancer. Importantly, we discuss strategies that target DDR proteins, including PARP, CHK1 and WEE1, as monotherapies or in combination with cytotoxic agents in the treatment of EC and highlight the compounds currently being evaluated for their efficacy in EC in clinic. Recent studies indicate that the application of DNA damage agents in cancer cells leads to the activation of innate and adaptive immune responses; targeting immune checkpoint proteins could overcome the immune suppressive environment in tumors. We further summarize recently revolutionized immunotherapies that have been completed or are now being evaluated for their efficacy in advanced EC and propose future directions for the development of DDR-based cancer therapeutics in the treatment of EC.