Radiation Therapy Promotes Hepatocellular Carcinoma Immune Cloaking via PD-L1 Upregulation Induced by cGAS-STING Activation

Tumor cell-intrinsic MELK enhanced CCL2-dependent immunosuppression to exacerbate hepatocarcinogenesis and confer resistance of HCC to radiotherapy

BACKGROUND

The outcome of hepatocellular carcinoma (HCC) is limited by its complex molecular characteristics and changeable tumor microenvironment (TME). Here we focused on elucidating the functional consequences of Maternal embryonic leucine zipper kinase (MELK) in the tumorigenesis, progression and metastasis of HCC, and exploring the effect of MELK on immune cell regulation in the TME, meanwhile clarifying the corresponding signaling networks.

METHODS

Bioinformatic analysis was used to validate the prognostic value of MELK for HCC. Murine xenograft assays and HCC lung metastasis mouse model confirmed the role of MELK in tumorigenesis and metastasis in HCC. Luciferase assays, RNA sequencing, immunopurification-mass spectrometry (IP-MS) and coimmunoprecipitation (CoIP) were applied to explore the upstream regulators, downstream essential molecules and corresponding mechanisms of MELK in HCC.

RESULTS

We confirmed MELK to be a reliable prognostic factor of HCC and identified MELK as an effective candidate in facilitating the tumorigenesis, progression, and metastasis of HCC; the effects of MELK depended on the targeted regulation of the upstream factor miR-505-3p and interaction with STAT3, which induced STAT3 phosphorylation and increased the expression of its target gene CCL2 in HCC. In addition, we confirmed that tumor cell-intrinsic MELK inhibition is beneficial in stimulating M1 macrophage polarization, hindering M2 macrophage polarization and inducing CD8 + T-cell recruitment, which are dependent on the alteration of CCL2 expression. Importantly, MELK inhibition amplified RT-related immune effects, thereby synergizing with RT to exert substantial antitumor effects. OTS167, an inhibitor of MELK, was also proven to effectively impair the growth and progression of HCC and exert a superior antitumor effect in combination with radiotherapy (RT).

CONCLUSIONS

Altogether, our findings highlight the functional role of MELK as a promising target in molecular therapy and in the combination of RT therapy to improve antitumor effect for HCC.

The balance of STING signaling orchestrates immunity in cancer

Over the past decade, it has become clear that the stimulator of interferon genes (STING) pathway is critical for a variety of immune responses. This endoplasmic reticulum-anchored adaptor protein has regulatory functions in host immunity across a spectrum of conditions, including infectious diseases, autoimmunity, neurobiology and cancer. In this Review, we outline the central importance of STING in immunological processes driven by expression of type I and III interferons, as well as inflammatory cytokines, and we look at therapeutic options for targeting STING. We also examine evidence that challenges the prevailing notion that STING activation is predominantly beneficial in combating cancer. Further exploration is imperative to discern whether STING activation in the tumor microenvironment confers true benefits or has detrimental effects. Research in this field is at a crossroads, as a clearer understanding of the nuanced functions of STING activation in cancer is required for the development of next-generation therapies.

Stimulator of Interferon Genes Protein (STING) Expression in Cancer Cells: A Tissue Microarray Study Evaluating More than 18,000 Tumors from 139 Different Tumor Entities

Stimulator of interferon genes protein (STING) activates the immune response in inflammatory cells. STING expression in cancer cells is less well characterized, but STING agonists are currently being evaluated as anticancer drugs. A tissue microarray containing 18,001 samples from 139 different tumor types was analyzed for STING by immunohistochemistry. STING-positive tumor cells were found in 130 (93.5%) of 139 tumor entities. The highest STING positivity rates occurred in squamous cell carcinomas (up to 96%); malignant mesothelioma (88.5%-95.7%); adenocarcinoma of the pancreas (94.9%), lung (90.3%), cervix (90.0%), colorectum (75.2%), and gallbladder (68.8%); and serous high-grade ovarian cancer (86.0%). High STING expression was linked to adverse phenotypes in breast cancer, clear cell renal cell carcinoma, colorectal adenocarcinoma, hepatocellular carcinoma, and papillary carcinoma of the thyroid (p < 0.05). In pTa urothelial carcinomas, STING expression was associated with low-grade carcinoma (p = 0.0002). Across all tumors, STING expression paralleled PD-L1 positivity of tumor and inflammatory cells (p < 0.0001 each) but was unrelated to the density of CD8+ lymphocytes. STING expression is variable across tumor types and may be related to aggressive tumor phenotype and PD-L1 positivity. The lack of relationship with tumor-infiltrating CD8+ lymphocytes argues against a significant IFN production by STING positive tumor cells.

Efficacy and Safety of Chidamide in Combination with PD-1 Inhibitor and Radiotherapy for HER2-Negative Advanced Breast Cancer: Study Protocol of a Single Arm Prospective Study

Purpose

As one of the most important breakthroughs in cancer therapy, immune checkpoint inhibitors have greatly prolonged survival of patients with breast cancer. However, their application and efficacy are limited, especially for advanced HER2-negative breast cancer. It has been reported that epigenetic modulation of the histone deacetylase (HDAC) inhibitor chidamide, as well as immune microenvironment modulation of radiotherapy are potentially synergistic with immunotherapy. Thus, the combination of chidamide, radiotherapy and immunotherapy is expected to improve prognosis of patients with advanced HER2-negative breast cancer.

Patients and Methods

This is a single-arm, open, prospective clinical trial investigating the efficacy and safety of the combination of HDAC inhibitor chidamide, anti-PD-1 antibody sintilimab, and the novel immuno-radiotherapy, which aims to enhance efficacy of immunotherapy, in subsequent lines of therapy of HER2-negative breast cancer. Our study will include 35 patients with advanced breast cancer that has failed endocrine therapy and first-line chemotherapy. Participants will receive 30 mg of chidamide twice a week, 200 mg of sintilimab once every 3 weeks, combined with immuno-radiotherapy. Radiotherapy will be centrally 8 Gy for at least one lesion, and at least 1 Gy for the other lesions. We will complete three fractions of radiotherapy in one cycle. The primary endpoint is progression-free survival, and secondary endpoints are objective response rate, disease control rate and safety. Moreover, biomarkers including cytokines and lymphocyte subgroups will be explored.

Conclusion

As a single-arm clinical trial, the analysis of the influence of each single treatment is limited. Besides, our study is an open study, which involves neither randomization nor blinding. In spite of the abovementioned limitations, this prospective clinical trial will give an insight into subsequent lines of therapy of HER2-negative advanced breast cancer, prolong the survival or achieve long remission for these participants, and identify potential responders.

Efficacy and safety of concurrent immune checkpoint inhibitors combined with radiotherapy or chemoradiotherapy for advanced non-small cell lung cancer: A systematic review and single-arm meta-analysis

BACKGROUND

The recent usage of immunotherapy combined with chemoradiotherapy has improved survival in advanced non-small cell lung cancer (NSCLC) patients. However, determining the most effective therapy combination remains a topic of debate. Research suggests immune checkpoint inhibitors (ICIs) post-chemoradiotherapy enhance survival, but the impact of concurrent ICIs during chemoradiotherapy on rapid disease progression is unclear. This meta-analysis aims to assess the effectiveness and safety of concurrent ICIs with radiotherapy or chemoradiotherapy in advanced non-small cell lung cancer.

METHODS

We searched PubMed, Embase, the Cochrane Library, and Web of Science for relevant studies, extracting data on overall response rate (ORR), progression-free survival (PFS), overall survival (OS), and adverse events (AEs).

RESULTS

The analysis included ten studies with 490 participants. Stage III NSCLC ORR was 81.8%, while Stage IV ORR was 39.9%. One-year PFS and OS for Stage III were 68.2% and 82.6%, compared to 27.9% and 72.2% for Stage IV. Common adverse events included anemia (46.6%), nausea (47.6%), rash (36.4%), and radiation pneumonitis (36.3%).

CONCLUSIONS

Our meta-analysis shows concurrent ICIs with chemoradiotherapy are effective and safe in advanced NSCLC, particularly in stage III patients at risk of progression before starting ICIs after chemoradiotherapy. The findings support further phase III trials. The review protocol was registered on PROSPERO (CRD42023493685) and is detailed on the NIHR HTA programme website.

Radiotherapy enhances efficacy of PD-1 inhibitors in advanced hepatocellular carcinoma: A propensity-matched real-world study

BACKGROUND

To address the need for immunotherapy in patients with advanced primary hepatocellular carcinoma (HCC), combination with radiotherapy (RT) has emerged as a promising strategy. In preclinical studies, irradiated tumors released tumor antigens to synergistically increase the antitumor effect of immunotherapy. Hence, we investigated whether RT enhances the efficacy of anti-programmed death receptor-1 (PD-1) inhibitors in advanced HCC in real-world practice.

METHODS

Between August 2018 and June 2021, 172 patients with advanced primary HCC were enrolled in the tertiary center (Zhongshan Hospital of Fudan University); 95 were treated with a combination of RT and the inhibitor of PD-1 (RT-PD1 cohort), and 77 were administered anti-PD-1 therapy (PD1 cohort). The first cycle of PD-1 inhibitors was administered within 60 days or concurrently with RT. Propensity score matching for bias reduction was used to evaluate the clinical outcomes.

RESULTS

Among 71 propensity-matched pairs, median progression-free survival was 5.7 months in the RT-PD1 cohort vs. 2.9 months in the PD1 cohort ( P  <0.001). Median overall survival was 20.9 months in the RT-PD1 cohort vs. 11.2 months in the PD1 cohort ( P  = 0.018). Compared with patients in the PD1 cohort, patients in the RT-PD1 cohort had significantly higher objective response rates (40.8%, 29/71 vs. 19.7%, 14/71, P  = 0.006) and disease control rates (62.0%, 44/71 vs. 31.0%, 22/71, P  <0.001). The incidences of toxic effects were not significantly different between the two cohorts.

CONCLUSIONS

RT plus anti-PD-1 therapy is well tolerated. RT enhances the efficacy of anti-PD-1 therapy in patients with advanced primary HCC by improving survival outcomes without increased toxic effects.

The role of the immunosuppressive PD-1/PD-L1 checkpoint pathway in the aging process and age-related diseases

The accumulation of senescent cells within tissues is a hallmark of the aging process. Senescent cells are also commonly present in many age-related diseases and in the cancer microenvironment. The escape of abnormal cells from immune surveillance indicates that there is some defect in the function of cytotoxic immune cells, e.g., CD8+ T cells and natural killer (NK) cells. Recent studies have revealed that the expression of programmed death-ligand 1 (PD-L1) protein is abundantly increased in senescent cells. An increase in the amount of PD-L1 protein protects senescent cells from clearance by the PD-1 checkpoint receptor in cytotoxic immune cells. In fact, the activation of the PD-1 receptor suppresses the cytotoxic properties of CD8+ T and NK cells, promoting a state of immunosenescence. The inhibitory PD-1/PD-L1 checkpoint pathway acts in cooperation with immunosuppressive cells; for example, activation of PD-1 receptor can enhance the differentiation of regulatory T cells (Treg), myeloid-derived suppressor cells (MDSC), and M2 macrophages, whereas the cytokines secreted by immunosuppressive cells stimulate the expression of the immunosuppressive PD-L1 protein. Interestingly, many signaling pathways known to promote cellular senescence and the aging process are crucial stimulators of the expression of PD-L1 protein, e.g., epigenetic regulation, inflammatory mediators, mTOR-related signaling, cGAS-STING pathway, and AhR signaling. It seems that the inhibitory PD-1/PD-L1 immune checkpoint axis has a crucial role in the accumulation of senescent cells and thus it promotes the aging process in tissues. Thus, the blockade of the PD-1/PD-L1 checkpoint signaling might be a potential anti-aging senolytic therapy. KEY MESSAGES: Senescent cells accumulate within tissues during aging and age-related diseases. Senescent cells are able to escape immune surveillance by cytotoxic immune cells. Expression of programmed death-ligand 1 (PD-L1) markedly increases in senescent cells. Age-related signaling stimulates the expression of PD-L1 protein in senescent cells. Inhibitory PD-1/PD-L1 checkpoint pathway suppresses clearance of senescent cells.

The dual function of cGAS-STING signaling axis in liver diseases

Numerous liver diseases, such as nonalcoholic fatty liver disease, hepatitis, hepatocellular carcinoma, and hepatic ischemia-reperfusion injury, have been increasingly prevalent, posing significant threats to global health. In recent decades, there has been increasing evidence linking the dysregulation of cyclic-GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING)-related immune signaling to liver disorders. Both hyperactivation and deletion of STING can disrupt the immune microenvironment dysfunction, exacerbating liver disorders. Consequently, there has been a surge in research investigating medical agents or mediators targeting cGAS-STING signaling. Interestingly, therapeutic manipulation of the cGAS-STING pathway has yielded inconsistent and even contradictory effects on different liver diseases due to the distinct physiological characteristics of intrahepatic cells that express and respond to STING. In this review, we comprehensively summarize recent advancements in understanding the dual roles of the STING pathway, highlighting that the benefits of targeting STING signaling depend on the specific types of target cells and stages of liver injury. Additionally, we offer a novel perspective on the suitability of STING agonists and antagonists for clinical assessment. In conclusion, STING signaling remains a highly promising therapeutic target, and the development of STING pathway modulators holds great potential for the treatment of liver diseases.

BIBR1532 combined with radiotherapy induces ferroptosis in NSCLC cells and activates cGAS-STING pathway to promote anti-tumor immunity

BACKGROUND

Telomerase, by safeguarding damaged telomeres and bolstering DNA damage repair, has the capacity to heighten the radioresistance of tumour cells. Thus, in turn, can compromise the efficacy of radiotherapy (RT) and radioimmunotherapy. Our previous studies have revealed that the highly selective telomerase inhibitor, BIBR1532, possesses the potential to enhance the radiosensitivity of Non-small cell lung cancer (NSCLC). In this study, we delve further into the impact of BIBR1532 on the immune activation induced by RT and elucidate the underlying mechanisms.

METHODS

Biological information analyses, immunofluorescence assays, western blot assays, flow cytometry analysis were conducted to elucidate the functions of the combination of BIBR1532 with radiotherapy in NSCLC. Intracellular levels of lipid peroxides, glutathione, malondialdehyde, and Fe2+ were measured as indicators of ferroptosis status. Both in vitro and in vivo studies were conducted to examine the antitumor effects.

RESULTS

Our findings indicate that the confluence of BIBR1532 with RT significantly augments the activation of the cGAS-STING pathway in both in vivo and in vitro settings, thereby fostering an effective anti-tumoral immune response. The effects can be ascribed to two key processes. Firstly, ionizing radiation, in precipitating DNA double-strand breaks (DSBs), prompts the release of tumour-derived double-stranded DNA (dsDNA) into the cytoplasm. Subsequently, BIBR1532 amplifies the activation of antigen-presenting cells by dsDNA post-RT and instigates the cGAS-STING pathway. Secondly, BIBR1532 enhances the ferroptosis response in NSCLC following RT, thereby promoting unrestrained lipid peroxidation and elevated levels of reactive oxygen species (ROS) within tumour cells. This ultimately leads to mitochondrial stress and the release of endogenous mitochondrial DNA (mtDNA) into the cytoplasm, thus facilitating the activation of the STING pathway and the induction of a type I interferon (IFN)-linked adaptive immune response.

CONCLUSION

This study underscores the potential of BIBR1532 as an efficacious and safe radiosensitizer and radioimmunotherapy synergist, providing robust preclinical research evidence for the treatment of NSCLC.

A Novel Nomogram to Predict Prognosis of Advanced Hepatocellular Carcinoma Treated with Intensity-Modulated Radiotherapy Plus Anti-PD1

Purpose

The combination of radiotherapy and monoclonal antibody against programmed cell death 1 (anti-PD1) showed preliminary efficacy in hepatocellular carcinoma (HCC). This study aimed to identify the prognostic factors and construct a nomogram to predict the overall survival (OS) of patients with advanced HCC after treatment with intensity-modulated radiotherapy (IMRT) plus anti-PD1.

Patients and Methods

The OS and progression-free survival (PFS) of 102 patients with BCLC stage C HCC was analyzed using the Kaplan-Meier method. Potential independent prognostic factors were determined using univariate and multivariate Cox regression analyses. A nomogram was established to predict prognosis whose accuracy and reliability was verified by a calibration curve and area under the receiver operating characteristic curve (AUROC).

Results

The median PFS and OS rates of the 102 patients with advanced HCC were 9.9 months and 14.3 months, respectively. Ninety-three patients were evaluated for efficacy, including five (5.38%) with complete response and 48 (51.61%) with partial response, with an overall response rate of 56.99%. Grade 3 and 4 adverse reactions (AEs) were observed in 32.35% of patients; no grade 5 AEs occurred. Multivariate Cox analysis revealed albumin and alpha-fetoprotein levels, neutrophil counts 3-4 weeks after IMRT initiation, and platelet-to-lymphocyte ratio 3-4 weeks after IMRT initiation to be independent prognostic factors. The nomogram model constructed using these factors had good consistency and accuracy with 1-3 years AUROC of 78.7, 78.6, and 93.5, respectively.

Conclusion

IMRT plus anti-PD1 showed promising efficacy and controllable adverse reactions in treating advanced HCC. The nomogram model demonstrated good reliability and clinical applicability.

DNA sensing of dendritic cells in cancer immunotherapy

Dendritic cells (DCs) are involved in the initiation and maintenance of immune responses against malignant cells by recognizing conserved pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) through pattern recognition receptors (PRRs). According to recent studies, tumor cell-derived DNA molecules act as DAMPs and are recognized by DNA sensors in DCs. Once identified by sensors in DCs, these DNA molecules trigger multiple signaling cascades to promote various cytokines secretion, including type I IFN, and then to induce DCs mediated antitumor immunity. As one of the potential attractive strategies for cancer therapy, various agonists targeting DNA sensors are extensively explored including the combination with other cancer immunotherapies or the direct usage as major components of cancer vaccines. Moreover, this review highlights different mechanisms through which tumor-derived DNA initiates DCs activation and the mechanisms through which the tumor microenvironment regulates DNA sensing of DCs to promote tumor immune escape. The contributions of chemotherapy, radiotherapy, and checkpoint inhibitors in tumor therapy to the DNA sensing of DCs are also discussed. Finally, recent clinical progress in tumor therapy utilizing agonist-targeted DNA sensors is summarized. Indeed, understanding more about DNA sensing in DCs will help to understand more about tumor immunotherapy and improve the efficacy of DC-targeted treatment in cancer.

RNA m5C methylation: a potential modulator of innate immune pathways in hepatocellular carcinoma

RNA 5-methylcytosine (m5C) methylation plays a crucial role in hepatocellular carcinoma (HCC). As reported, aberrant m5C methylation is closely associated with the progression, therapeutic efficacy, and prognosis of HCC. The innate immune system functions as the primary defense mechanism in the body against pathogenic infections and tumors since it can activate innate immune pathways through pattern recognition receptors to exert anti-infection and anti-tumor effects. Recently, m5C methylation has been demonstrated to affect the activation of innate immune pathways including TLR, cGAS-STING, and RIG-I pathways by modulating RNA function, unveiling new mechanisms underlying the regulation of innate immune responses by tumor cells. However, research on m5C methylation and its interplay with innate immune pathways is still in its infancy. Therefore, this review details the biological significance of RNA m5C methylation in HCC and discusses its potential regulatory relationship with TLR, cGAS-STING, and RIG-I pathways, thereby providing fresh insights into the role of RNA methylation in the innate immune mechanisms and treatment of HCC.

Can rectal MRI and endorectal ultrasound accurately predict the complete response to neoadjuvant immunotherapy for rectal cancer?

Background

Standardized assessments of clinical complete response (cCR) to neoadjuvant chemoradiotherapy (nCRT) for rectal cancer have been established, but their utility and accuracy remain unclear. This study aimed to evaluate the clinical diagnostic value of rectal magnetic resonance imaging (MRI) and endorectal ultrasonography (ERUS) for the determination of cCRs after neoadjuvant immunotherapy and to investigate the concordance between cCR and pathological complete response (pCR).

Methods

Ninety-four patients with rectal cancer treated with neoadjuvant radiotherapy with or without immunotherapy were included. The sensitivity, specificity, and accuracy of each evaluation method were calculated.

Results

Combined MRI and ERUS assessments found cCR in seven of the 94 patients in our cohort. In the non-immunotherapy group, the sensitivity, specificity, and accuracy of MRI for diagnosing cCR were 50.0%, 85.2%, and 77.1%, respectively, whereas those of ERUS were 50.0%, 92.6%, and 82.9%, respectively; those of combined MRI and ERUS were 25.0%, 96.3%, and 87.5%, respectively. In the immunotherapy group, the sensitivity, specificity, and accuracy with which MRI identified CR were 51.7%, 76.7%, and 64.4%, respectively; those of ERUS were 13.8%, 90.0%, and 52.5%, respectively, and those of combined MRI and ERUS were 10.3%, 96.7%, and 54.2%, respectively. We also found that 32 of 37 patients with pCR did not meet the cCR evaluation criteria. Of these pCR patients, 78.4% (29/37) received immunotherapy. In the entire cohort, there were five pCRs among the seven cCRs. Of the four cCRs that occurred in the immunotherapy group, three were pCRs.

Conclusions

Rectal MRI and/or ERUS did not provide sufficiently accurate assessments of cCR in patients with rectal cancer receiving neoadjuvant therapy, especially immunotherapy, and cCR did not predict pCR.

Roles of cGAS-STING Pathway in Radiotherapy Combined with Immunotherapy for Hepatocellular Carcinoma

Although great strides have been made in the management and treatment of hepatocellular carcinoma (HCC), its prognosis is still poor yielding a high mortality. Immunotherapy is recommended for treating advanced HCC, but its efficiency is hampered because of hepatic immunosuppression. Stimulator of interferon genes (STING) pathway, serving as a critical cytoplasmic DNA-sensing process, is reported to initiate the antitumor immune response, and link the innate immunity to the adaptive immune system. Radiotherapy has been well acknowledged to induce destruction and release of tumor-derived DNA into the cytoplasm, which then activates the cGAS-STING pathway. On this basis, radiotherapy can be used as a sensitizer for immunotherapy, and its combination with immunotherapy may bring in changes to the suboptimal efficacy of immune checkpoint inhibitor monotherapy. In this review, we summarized the roles of cGAS-STING pathway in regulation of radiotherapy combined with immunotherapy for treating HCC.

RECQL4 Inhibits Radiation-Induced Tumor Immune Awakening via Suppressing the cGAS-STING Pathway in Hepatocellular Carcinoma

Many patients with hepatocellular carcinoma (HCC) respond poorly to radiotherapy despite remarkable advances in treatment. A deeper insight into the mechanism of sensitivity of HCC to this therapy is urgently required. It is demonstrated that RECQL4 is upregulated in the malignant cells of patients with HCC. Elevated RECQL4 levels reduce the sensitivity of HCC to radiotherapy by repairing radiation-induced double-stranded DNA (dsDNA) fragments. Mechanistically, the inhibitory effect of RECQL4 on radiotherapy is due to the reduced recruitment of dendritic cells and CD8+ T cells in the tumor microenvironment (TME). RECQL4 disrupts the radiation-induced transformation of the TME into a tumoricidal niche by inhibiting the cGAS-STING pathway in dendritic cells. Knocking out STING in dendritic cells can block the impact of RECQL4 on HCC radiosensitivity. Notably, high RECQL4 expressions in HCC is significantly associated with poor prognosis in multiple independent cohorts. In conclusion, this study highlights how HCC-derived RECQL4 disrupts cGAS-STING pathway activation in dendritic cells through DNA repair, thus reducing the radiosensitivity of HCC. These findings provide new perspectives on the clinical treatment of HCC.

Melanoma Derived Exosomes Amplify Radiotherapy Induced Abscopal Effect via IRF7/I-IFN Axis in Macrophages

Radiotherapy (RT) can induce tumor regression outside the irradiation field, known as the abscopal effect. However, the detailed underlying mechanisms remain largely unknown. A tumor-bearing mouse model is successfully constructed by inducing both subcutaneous tumors and lung metastases. Single-cell RNA sequencing, immunofluorescence, and flow cytometry are performed to explore the regulation of tumor microenvironment (TME) by RT. A series of in vitro assays, including luciferase reporter, RNA Pulldown, and fluorescent in situ hybridization (FISH) assays, are performed to evaluate the detailed mechanism of the abscopal effect. In addition, in vivo assays are performed to investigate combination therapy strategies for enhancing the abscopal effect. The results showed that RT significantly inhibited localized tumor and lung metastasis progression and improved the TME. Mechanistically, RT promoted the release of tumor-derived exosomes carrying circPIK3R3, which is taken up by macrophages. circPIK3R3 promoted Type I interferon (I-IFN) secretion and M1 polarization via the miR-872-3p/IRF7 axis. Secreted I-IFN activated the JAK/STAT signaling pathway in CD8+ T cells, and promoted IFN-γ and GZMB secretion. Together, the study shows that tumor-derived exosomes promote I-IFN secretion via the circPIK3R3/miR-872-3p/IRF7 axis in macrophages and enhance the anti-tumor immune response of CD8+ T cells.

Arginine methylation-dependent cGAS stability promotes non-small cell lung cancer cell proliferation

Cyclic GMP-AMP synthase (cGAS), promotes non-small cell lung cancer (NSCLC) cell proliferation. However, the specific mechanisms of cGAS-mediated NSCLC cell proliferation are largely unknown. In this study, we found asymmetric dimethylation by protein arginine methyltransferase 1 (PRMT1) at R127 of cGAS. This facilitated the binding of deubiquitinase USP7 and contributed to deubiquitination and stabilization of cGAS. PRMT1-and USP7-dependent cGAS stability, which also played a pivotal role in accelerating NSCLC cell proliferation through activating AKT pathway. We validated that the expression of cGAS and PRMT1 were positive correlated in human non-small cell lung cancer samples. Our study demonstrates a unique mechanism for managing cGAS stability by arginine methylation and indicates that PRMT1-cGAS-USP7 axis is a potential therapeutic target for NSCLC.

Targeting two radiation-induced immunosuppressive pathways to improve the efficacy of normofractionated radiation therapy in a preclinical colorectal cancer model

PURPOSE

We have previously demonstrated in a murine colorectal cancer model that normofractionated RT (normoRT: 18 × 2 Gy) induced MDSC infiltration and PD-L1 expression, while hypofractionated RT (hypoRT: 3 × 8 Gy) induced Treg. Here, we wanted to assess whether the association of normoRT with treatments that target two radiation-induced immunosuppressive pathways (MDSC and PD-L1) could improve tumor control.

MATERIALS AND METHODS

Subcutaneous tumors were induced using colon tumor cells (CT26) in immunocompetent mice (BALB/c) and were treated with RT alone (18 × 2 Gy or 3 × 8 Gy), or concomitantly with 5-Fluorouracil (5FU) (10 mg/kg) to deplete MDSC, and/or anti-PD-L1 (10 mg/kg). We assessed the impact of these combinations on tumor growth and immune cells infiltration by flow cytometry. In addition, we performed tumor rechallenge experiments and IFN-γ ELISpots to study the long-term memory response.

RESULTS

Even though tumor growth was significantly delayed in the RT + 5FU compared to 5FU and untreated groups (p < .05), there was no significant difference between RT + 5FU (CRT) and RT alone. The rate of MDSC increased significantly 1 week after the end of normoRT (8.09% ± 1.03%, p < .05) and decreased with the addition of 5FU (3.39% ± 0.69%, p < .05). PD-L1 expressing tumor cells were increased after treatment. Adding anti-PD-L1 significantly delayed tumor growth, achieved the highest complete response rate, and induced a long-lasting protective specific anti-tumor immunity.

CONCLUSIONS

These results tend to demonstrate the interest of inhibiting two radiation-induced immunosuppressive mechanisms. In patients, the combination of normoRT with 5FU is already the standard of care in locally advanced rectal cancer. Adding an anti-PD-L1 to this treatment could show promising results.

MicroRNAs as regulators of immune checkpoints in cancer immunotherapy: targeting PD-1/PD-L1 and CTLA-4 pathways

Immunotherapy has revolutionized cancer treatment by harnessing the power of the immune system to eliminate tumors. Immune checkpoint inhibitors (ICIs) block negative regulatory signals that prevent T cells from attacking cancer cells. Two key ICIs target the PD-1/PD-L1 pathway, which includes programmed death-ligand 1 (PD-L1) and its receptor programmed death 1 (PD-1). Another ICI targets cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). While ICIs have demonstrated remarkable efficacy in various malignancies, only a subset of patients respond favorably. MicroRNAs (miRNAs), small non-coding RNAs that regulate gene expression, play a crucial role in modulating immune checkpoints, including PD-1/PD-L1 and CTLA-4. This review summarizes the latest advancements in immunotherapy, highlighting the therapeutic potential of targeting PD-1/PD-L1 and CTLA-4 immune checkpoints and the regulatory role of miRNAs in modulating these pathways. Consequently, understanding the complex interplay between miRNAs and immune checkpoints is essential for developing more effective and personalized immunotherapy strategies for cancer treatment.

Silencing PinX1 enhances radiosensitivity and antitumor-immunity of radiotherapy in non-small cell lung cancer

BACKGROUND

We aimed to investigate the effects of PinX1 on non-small cell lung cancer(NSCLC) radiosensitivity and radiotherapy-associated tumor immune microenvironment and its mechanisms.

METHODS

The effect of PinX1 silencing on radiosensitivity in NSCLC was assessed by colony formation and CCK8 assay, immunofluorescence detection of γ- H2AX and micronucleus assay. Western blot was used to assess the effect of PinX1 silencing on DNA damage repair pathway and cGAS-STING pathway. The nude mouse and Lewis lung cancer mouse model were used to assess the combined efficacy of PinX1 silencing and radiotherapy in vivo. Changes in the tumor immune microenvironment were assessed by flow cytometry for different treatment modalities in the Lewis luuse model. The interaction protein RBM10 was screened by immunoprecipitation-mass spectrometry.

RESULTS

Silencing PinX1 enhanced radiosensitivity and activation of the cGAS-STING pathway while attenuating the DNA damage repair pathway. Silencing PinX1 further increases radiotherapy-stimulated CD8+ T cell infiltration and activation, enhances tumor control and improves survival in vivo; Moreover, PinX1 downregulation improves the anti-tumor efficacy of radioimmunotherapy, increases radioimmune-stimulated CD8+ T cell infiltration, and reprograms M2-type macrophages into M1-type macrophages in tumor tissues. The interaction of PinX1 and RBM10 may promote telomere maintenance by assisting telomerase localization to telomeres, thereby inhibiting the immunostimulatory effects of IR.

CONCLUSIONS

In NSCLC, silencing PinX1 significantly contributed to the radiosensitivity and promoted the efficacy of radioimmunotherapy. Mechanistically, PinX1 may regulate the transport of telomerase to telomeres through interacting with RBM10, which promotes telomere maintenance and DNA stabilization. Our findings reveal that PinX1 is a potential target to enhance the efficacy of radioimmunotherapy in NSCLC patients.

Tertiary lymphoid structures in cancer: immune mechanisms and clinical implications

Cancer is a major cause of death globally, and traditional treatments often have limited efficacy and adverse effects. Immunotherapy has shown promise in various malignancies but is less effective in tumors with low immunogenicity or immunosuppressive microenvironment, especially sarcomas. Tertiary lymphoid structures (TLSs) have been associated with a favorable response to immunotherapy and improved survival in cancer patients. However, the immunological mechanisms and clinical significance of TLS in malignant tumors are not fully understood. In this review, we elucidate the composition, neogenesis, and immune characteristics of TLS in tumors, as well as the inflammatory response in cancer development. An in-depth discussion of the unique immune characteristics of TLSs in lung cancer, breast cancer, melanoma, and soft tissue sarcomas will be presented. Additionally, the therapeutic implications of TLS, including its role as a marker of therapeutic response and prognosis, and strategies to promote TLS formation and maturation will be explored. Overall, we aim to provide a comprehensive understanding of the role of TLS in the tumor immune microenvironment and suggest potential interventions for cancer treatment.

Nanoscale Metal-Organic Frameworks-Mediated Degradation of Mutant p53 Proteins and Activation of cGAS-STING Pathway for Enhanced Cancer Immunotherapy

Activating cGAS-STING pathway has great potential to achieve effective antitumor immunotherapy. However, mutant p53 (mutp53), a commonly observed genetic alteration in over 50% of human cancer, will impede the therapeutic performance of the cGAS-STING pathway. Herein, multifunctional ZIF-8@MnO2 nanoparticles are constructed to degrade mutp53 and facilitate the cGAS-STING pathway. The synthesized ZIF-8@MnO2 can release Zn2+ and Mn2+ in cancer cells to induce oxidative stress and cytoplasmic leakage of fragmented mitochondrial double-stranded DNAs (dsDNAs). Importantly, the released Zn2+ induces variable degradation of multifarious p53 mutants through proteasome ubiquitination, which can alleviate the inhibitory effects of mutp53 on the cGAS-STING pathway. In addition, the released Mn2+ further increases the sensitivity of cGAS to dsDNAs as immunostimulatory signals. Both in vitro and in vivo results demonstrate that ZIF-8@MnO2 effectively promotes the cGAS-STING pathway and synergizes with PD-L1 checkpoint blockades, leading to remarkable regression of local tumors as well as distant metastases of breast cancer. This study proposes an inorganic metal ion-based nanoplatform to enhance the cGAS-STING-mediated antitumor immunotherapy, especially to those tumors with mutp53 expression.

LAIR1-mediated resistance of hepatocellular carcinoma cells to T cells through a GSK-3β/β-catenin/MYC/PD-L1 pathway

BACKGROUND

An increasing number of studies have reported the involvement of oncogenes in the regulation of the immune system. LAIR1 is an immunosuppressive molecule and its role in immune-related diseases has been mainly reported. To date, it is unclear whether LAIR1 in tumor cells is involved in immune regulation. Therefore, the aim of this study was to investigate the role of LAIR1 in the immune microenvironment of hepatocellular carcinoma (HCC) to seek the novel therapeutic discoveries.

METHODS

Tumor Immune Dysfunction and Exclusion database was used to predict the response of LAIR1 expression to immune checkpoint blockade. CD8+ T cells were co-cultured with HCC cells, and the killing efficiency of leukocytes on HCC cells was detected by flow cytometry. Flow cytometry was also used to detect the expression of inhibitory receptors. In addition, Western blot, immunofluorescence, and nucleus/cytoplasm fractionation experiments were performed to explore the molecular mechanisms by which LAIR1 created a suppressive tumor microenvironment.

RESULTS

LAIR1 expression in HCC was associated with worse immune prognosis and T-cell dysfunction. HCC cells overexpressing LAIR1 co-cultured with CD8+ T cells induced exhaustion of latter. Mechanism studies indicated that LAIR1 in HCC cells up-regulated the phosphorylation of β-catenin by inducing the phosphorylation of GSK-3β, leading to the impairment of the expression and the nuclear localization signal of β-catenin. Low β-catenin expression and nuclear localization signal inhibited MYC-mediated PD-L1 expression. Therefore, PD-L1 up-regulated by LAIR1 caused the exhaustion of infiltrating CD8+ T cells in HCC, which aggravated the malignant progression of HCC.

CONCLUSION

LAIR1 increased PD-L1 expression through the GSK-3β/β-catenin/MYC/PD-L1 pathway and promoted immune evasion of HCC cells. Targeted inhibition of LAIR1 helped to enhance the immune killing effect of CD8+ T cells in HCC.

Immune modulatory roles of radioimmunotherapy: biological principles and clinical prospects

Radiation therapy (RT) not only can directly kill tumor cells by causing DNA double-strand break, but also exerts anti-tumor effects through modulating local and systemic immune responses. The immunomodulatory effects of RT are generally considered as a double-edged sword. On the one hand, RT effectively enhances the immunogenicity of tumor cells, triggers type I interferon response, induces immunogenic cell death to activate immune cell function, increases the release of proinflammatory factors, and reshapes the tumor immune microenvironment, thereby positively promoting anti-tumor immune responses. On the other hand, RT stimulates tumor cells to express immunosuppressive cytokines, upregulates the function of inhibitory immune cells, leads to lymphocytopenia and depletion of immune effector cells, and thus negatively suppresses immune responses. Nonetheless, it is notable that RT has promising abscopal effects and may achieve potent synergistic effects, especially when combined with immunotherapy in the daily clinical practice. This systematic review will provide a comprehensive profile of the latest research progress with respect to the immunomodulatory effects of RT, as well as the abscopal effect of radioimmunotherapy combinations, from the perspective of biological basis and clinical practice.

Olaparib enhances radiation-induced systemic anti-tumor effects via activating STING-chemokine signaling in hepatocellular carcinoma

Although Poly (ADP-ribose) polymerase (PARP) inhibitors have been clinically approved for cancers with BRCA mutations and are known to augment radiotherapy responses, their roles in promoting the abscopal effect and mediating immunotherapy in BRCA-proficient hepatocellular carcinoma (HCC) remain underexplored. Our study elucidates that olaparib enhances the radio-sensitivity of HCC cells. Coadministration of olaparib and irradiation induces significant DNA damage by generating double-strand breaks (DSBs), as revealed both in vitro and in immune-deficient mice. These DSBs activate the cGAS-STING pathway, initiating immunogenic cell death in abscopal tumors. STING activation reprograms the immune microenvironment in the abscopal tumors, triggering the release of type I interferon and chemokines, including CXCL9, CXCL10, CXCL11, and CCL5. This in turn amplifies T cell priming against tumor neoantigens, leading to an influx of activated, neoantigen-specific CD8+ T-cells within the abscopal tumors. Furthermore, olaparib attenuated the immune exhaustion induced by radiation and enhances the responsiveness of HCC to immune checkpoint inhibitors. Collectively, our data advocate that a synergistic regimen of PARP inhibitors and radiotherapy can strategically reinforce both local (primary) and systemic (abscopal) tumor control, bolstering HCC susceptibility to immunotherapy.

Tumor immunotherapy resistance: Revealing the mechanism of PD-1 / PD-L1-mediated tumor immune escape

Tumor immunotherapy, an innovative anti-cancer therapy, has showcased encouraging outcomes across diverse tumor types. Among these, the PD-1/PD-L1 signaling pathway is a well-known immunological checkpoint, which is significant in the regulation of immune evasion by tumors. Nevertheless, a considerable number of patients develop resistance to anti-PD-1/PD-L1 immunotherapy, rendering it ineffective in the long run. This research focuses on exploring the factors of PD-1/PD-L1-mediated resistance in tumor immunotherapy. Initially, the PD-1/PD-L1 pathway is characterized by its role in facilitating tumor immune evasion, emphasizing its role in autoimmune homeostasis. Next, the primary mechanisms of resistance to PD-1/PD-L1-based immunotherapy are analyzed, including tumor antigen deletion, T cell dysfunction, increased immunosuppressive cells, and alterations in the expression of PD-L1 within tumor cells. The possible ramifications of altered metabolism, microbiota, and DNA methylation on resistance is also described. Finally, possible resolution strategies for dealing with anti-PD-1/PD-L1 immunotherapy resistance are discussed, placing particular emphasis on personalized therapeutic approaches and the exploration of more potent immunotherapy regimens.

STING Agonist-Loaded Nanoparticles Promotes Positive Regulation of Type I Interferon-Dependent Radioimmunotherapy in Rectal Cancer

Hypoxia-associated radioresistance in rectal cancer (RC) has severely hampered the response to radioimmunotherapy (iRT), necessitating innovative strategies to enhance RC radiosensitivity and improve iRT efficacy. Here, a catalytic radiosensitizer, DMPtNPS, and a STING agonist, cGAMP, are integrated to overcome RC radioresistance and enhance iRT. DMPtNPS promotes efficient X-ray energy transfer to generate reactive oxygen species, while alleviating hypoxia within tumors, thereby increasing radiosensitivity. Mechanistically, the transcriptomic and immunoassay analysis reveal that the combination of DMPtNPS and RT provokes bidirectional regulatory effects on the immune response, which may potentially reduce the antitumor efficacy. To mitigate this, cGAMP is loaded into DMPtNPS to reverse the negative impact of DMPtNPS and RT on the tumor immune microenvironment (TiME) through the type I interferon-dependent pathway, which promotes cancer immunotherapy. In a bilateral tumor model, the combination treatment of RT, DMPtNPS@cGAMP, and αPD-1 demonstrates a durable complete response at the primary site and enhanced abscopal effect at the distant site. This study highlights the critical role of incorporating catalytic radiosensitizers and STING agonists into the iRT approach for RC.

cGAS-STING and PD1/PDL-1 pathway in breast cancer: a window to new therapies

Breast cancer is a complex malignancy with diverse molecular and cellular subtypes and clinical outcomes. Despite advances in treatment, breast cancer remains a significant health challenge. However, recent advances in cancer immunotherapy have shown promising results in the treatment of breast cancer, particularly the use of inhibitors that target the immune checkpoint PD1/PDL1. Also, the cGAS-STING pathway, an important part of the innate immune response, has been considered as a major potential therapeutic target for breast cancer. In this narrative review, we provide an overview of the cGAS-STING and PD1/PDL-1 pathway in breast cancer, including their role in tumor development, progression, and response to treatment. We also discuss potential future directions for research.

A pH-Sensitive Nanoparticle as Reactive Oxygen Species Amplifier to Regulate Tumor Microenvironment and Potentiate Tumor Radiotherapy

Background

Radiotherapy is a widely used clinical tool for tumor treatment but can cause systemic toxicity if excessive radiation is administered. Although numerous nanoparticles have been developed as radiosensitizers to reduce the required dose of X-ray irradiation, they often have limitations, such as passive reliance on radiation-induced apoptosis in tumors, and little consider the unique tumor microenvironment that contributes radiotherapy resistance.

Methods

In this study, we developed and characterized a novel self-assembled nanoparticle containing dysprosium ion and manganese ion (Dy/Mn-P). We systematically investigated the potential of Dy/Mn-P nanoparticles (NPs) as a reactive oxygen species (ROS) amplifier and radiosensitizer to enhance radiation therapy and modulate the tumor microenvironment at the cellular level. Additionally, we evaluated the effect of Dy/Mn-P on the stimulator of interferon genes (STING), an innate immune signaling pathway.

Results

Physicochemical analysis demonstrated the prepared Dy/Mn-P NPs exhibited excellent dispersibility and stability, and degraded rapidly at lower pH values. Furthermore, Dy/Mn-P was internalized by cells and exhibited selective toxicity towards tumor cells compared to normal cells. Our findings also revealed that Dy/Mn-P NPs improved the tumor microenvironment and significantly increased ROS generation under ionizing radiation, resulting in a ~70% increase in ROS levels compared to radiation therapy alone. This enhanced ROS generation inhibited ~92% of cell clone formation and greatly contributed to cytoplasmic DNA exposure. Subsequently, the activation of the STING pathway was observed, leading to the secretion of pro-inflammatory immune factors and maturation of dendritic cells (DCs).

Conclusion

Our study demonstrates that Dy/Mn-P NPs can potentiate tumor radiotherapy by improving the tumor microenvironment and increasing endogenous ROS levels within the tumor. Furthermore, Dy/Mn-P can amplify the activation of the STING pathway during radiotherapy, thereby triggering an anti-tumor immune response. This novel approach has the potential to expand the application of radiotherapy in tumor treatment.

Survival benefit of combined immunotherapy and chemoradiotherapy in locally advanced unresectable esophageal cancer: an analysis based on the SEER database

Background

While simultaneous chemoradiotherapy remains the established therapeutic modality for patients afflicted with locally advanced esophageal cancer, the effectiveness of this radical approach falls short of the desired outcome. Numerous investigations have illuminated the prospect of enhancing therapeutic efficacy through the amalgamation of chemoradiotherapy and immunotherapeutic interventions. Consequently, we embarked on an examination to scrutinize the potential survival advantages conferred by the confluence of chemoradiotherapy and immunotherapy in relation to locally advanced unresectable esophageal carcinoma, drawing upon the extensive SEER database for our analysis.

Methods

We extracted clinicopathological attributes and survival statistics of patients afflicted with locally advanced unresectable esophageal carcinoma, diagnosed within the temporal span encompassing the years 2004-2014 and 2019-2020, from the extensive SEER database. To discern disparities in both overall survival (OS) and cancer-specific survival (CSS) between the cohorts subjected to chemoradiotherapy combined with immunotherapy and chemoradiotherapy alone, we employed analytical tools such as Kaplan-Meier analysis, the Log-rank test, the Cox regression proportional risk model, and propensity-matched score (PSM) methodology.

Results

A total of 7,758 eligible patients were encompassed in this research, with 6,395 individuals having undergone chemoradiotherapy alone, while 1,363 patients received the combined treatment of chemoradiotherapy and immunotherapy. After 1:4 propensity score matching, 6,447 patients were successfully harmonized, yielding a well-balanced cohort. The Kaplan-Meier curves demonstrated a substantial enhancement in OS (P = 0.0091) and CSS (P < 0.001) for the group subjected to chemoradiotherapy combined with immunotherapy as compared to chemoradiotherapy alone. Further multivariable analysis with PSM confirmed that chemoradiotherapy combined with immunotherapy benefits OS(HR=0.89, 95% CI 0.81-0.98) and CSS (HR=0.68, 95% CI 0.61-0.76). In addition, Univariable and multivariable Cox regression analyses of the matched patient groups unveiled several independent prognostic factors for OS and CSS, including sex, age, marital status, tumor location, tumor size, pathologic grade, SEER historic staging, and treatment modality. Among these factors, being female, married, and receiving chemoradiotherapy combined with immunotherapy emerged as independent protective factors, while age exceeding 75 years, non-superior segment tumor location, tumor size greater than 6 cm, Grade 3-4 pathology, and regional SEER historic staging were all found to be independent risk factors. The survival advantage of the chemoradiotherapy combined with the immunotherapy group over the chemoradiotherapy alone group was substantial.

Conclusions

This investigation furnishes compelling evidence that the integration of immunotherapy with chemoradiotherapy confers a noteworthy survival advantage when contrasted with conventional chemoradiotherapy for individuals grappling with locally advanced unresectable esophageal carcinoma.

Recent progress, perspectives, and issues of engineered PD-L1 regulation nano-system to better cure tumor: A review

Currently, immune checkpoint blockade (ICB) therapies that target the programmed cell death ligand-1 (PD-L1) have been used as revolutionary cancer treatments in the clinic. Apart from restoring the antitumor response of cytotoxic T cells by blocking the interaction between PD-L1 on tumor cells and programmed cell death-1 (PD-1) on T cells, PD-L1 proteins were also newly revealed to possess the capacity to accelerate DNA damage repair (DDR) and enhance tumor growth through multiple mechanisms, leading to the impaired efficacy of tumor therapies. Nevertheless, current free anti-PD-1/PD-L1 therapy still suffered from poor therapeutic outcomes in most solid tumors due to the non-selective tumor accumulation, ineludible severe cytotoxic effects, as well as the common occurrence of immune resistance. Recently, nanoparticles with efficient tumor-targeting capacity, tumor-responsive prosperity, and versatility for combination therapy were identified as new avenues for PD-L1 targeting cancer immunotherapies. In this review, we first summarized the multiple functions of PD-L1 protein in promoting tumor growth, accelerating DDR, as well as depressing immunotherapy efficacy. Following this, the effects and mechanisms of current clinically widespread tumor therapies on tumor PD-L1 expression were discussed. Then, we reviewed the recent advances in nanoparticles for anti-PD-L1 therapy via using PD-L1 antibodies, small interfering RNA (siRNA), microRNA (miRNA), clustered, regularly interspaced, short palindromic repeats (CRISPR), peptide, and small molecular drugs. At last, we discussed the challenges and perspectives to promote the clinical application of nanoparticles-based PD-L1-targeting therapy.

Biomarkers for predicting tumor response to PD-1 inhibitors in patients with advanced pancreatic cancer

Pancreatic cancer is among the most lethal malignant neoplasms, and few patients with pancreatic cancer benefit from immunotherapy. We retrospectively analyzed advanced pancreatic cancer patients who received PD-1 inhibitor-based combination therapies during 2019-2021 in our institution. The clinical characteristics and peripheral blood inflammatory markers (neutrophil-to-lymphocyte ratio [NLR], platelet-to-lymphocyte ratio [PLR], lymphocyte-to-monocyte ratio [LMR], and lactate dehydrogenase [LDH]) were collected at baseline. Chi-squared and Fisher's exact tests were used to evaluate relationships between the above parameters and tumor response. Cox regression analyses were employed to assess the effects of baseline factors on patients' survival and immune-related adverse events (irAEs). Overall, 67 patients who received at least two cycles of PD-1 inhibitor were considered evaluable. A lower NLR was independent predictor for objective response rate (38.1% vs. 15.2%, P = .037) and disease control rate (81.0% vs. 52.2%, P = .032). In our study population, patients with lower LDH had superior progression-free survival (PFS) and overall survival(OS) (mPFS, 5.4 vs. 2.8 months, P < .001; mOS, 13.3 vs. 3.6 months, P < .001). Liver metastasis was verified to be a negative prognostic factor for PFS (2.4 vs. 7.8 months, P < .001) and OS (5.7 vs. 18.0 months, P < .001). The most common irAEs were hypothyroidism (13.4%) and rash (10.5%). Our study demonstrated that the pretreatment inflammatory markers were independent predictors for tumor response, and the baseline LDH level and liver metastasis were potential prognostic markers of survival in patients with pancreatic cancer treated with PD-1 inhibitors.

Making "cold" tumors "hot"- radiotherapy remodels the tumor immune microenvironment of pancreatic cancer to benefit from immunotherapy: a case report

Immune checkpoint inhibitors have limited efficacy in metastatic pancreatic cancer due to the complex tumor immune microenvironment (TIME). Studies have shown that radiotherapy can cause cell lesions to release tumor antigens and then take part in the remodeling of the tumor environment and the induction of ectopic effects via regional and systemic immunoregulation. Here, we reported a case of advanced metastatic pancreatic cancer treated with immunotherapy combined with chemotherapy and radiotherapy and a sharp shift of the TIME from T3 to T2 was also observed. One hepatic metastasis within the planning target volume (PTV) was evaluated complete response (CR), the other one was evaluated partial response (PR) and 2 hepatic metastases outside the PTV were surprisingly considered PR. In the study, we found that immunotherapy combined with chemotherapy and radiotherapy achieved significant therapeutic benefits, which may provide a new strategy for the treatment of advanced pancreatic cancer.

PD-L1 blockade TAM-dependently potentiates mild photothermal therapy against triple-negative breast cancer

The present work was an endeavor to shed light on how mild photothermia possibly synergizes with immune checkpoint inhibition for tumor therapy. We established mild photothermal heating protocols to generate temperatures of 43 °C and 45 °C in both in vitro and in vivo mouse 4T1 triple-negative breast cancer (TNBC) models using polyglycerol-coated carbon nanohorns (CNH-PG) and 808 nm laser irradiation. Next, we found that 1) CNH-PG-mediated mild photothermia (CNH-PG-mPT) significantly increased expression of the immune checkpoint PD-L1 and type-1 macrophage (M1) markers in the TNBC tumors; 2) CNH-PG-mPT had a lower level of anti-tumor efficacy which was markedly potentiated by BMS-1, a PD-L1 blocker. These observations prompted us to explore the synergetic mechanisms of CNH-PG-mPT and BMS-1 in the context of tumor cell-macrophage interactions mediated by PD-L1 since tumor-associated macrophages (TAMs) are a major source of PD-L1 expression in tumors. In vitro, the study then identified two dimensions where BMS-1 potentiated CNH-PG-mPT. First, CNH-PG-mPT induced PD-L1 upregulation in the tumor cells and showed a low level of cytotoxicity which was potentiated by BMS-1. Second, CNH-PG-mPT skewed TAMs towards an M1-like anti-tumor phenotype with upregulated PD-L1, and BMS-1 bolstered the M1-like phenotype. The synergistic effects of BMS-1 and CNH-PG-mPT both on the tumor cells and TAMs were more pronounced when the two cell populations were in co-culture. Further in vivo study confirmed PD-L1 upregulation both in tumor cells and TAMs in the TNBC tumors following treatment of CNH-PG-mPT. Significantly, TAMs depletion largely abolished the anti-TNBC efficacy of CNH-PG-mPT alone and in synergy with BMS-1. Collectively, our findings reveal PD-L1 upregulation to be a key response of TNBC to mild photothermal stress, which plays a pro-survival role in the tumor cells while also acting as a brake on the M1-like activation of the TAMs. Blockade of mPT‑induced PD‑L1 achieves synergistic anti-TNBC efficacy by taking the intrinsic survival edge off the tumor cells on one hand and taking the brakes off the M1-like TAMs on the other. Our findings reveal a novel way (i.e. mild thermia plus PD-L1 blockade) to modulate the TAMs-tumor cell interaction to instigate a mutiny of the TAMs against their host tumor cells.

cGAS-STING signaling in the tumor microenvironment

The cGAS-STING signaling is an important pathway involved in the regulation of tumor microenvironment, which affects many cellular functions including immune activation. Its role in combating tumor progression is widely recognized, especially with its function in inducing innate and adaptive immune responses, on which many immunotherapies have been developed. However, a growing number of findings also suggest a diversity of its roles in shaping tumor microenvironment, including functions that promote tumor progression. Here, we summarize the functions of the cGAS-STING signaling in tumor microenvironment to maintain tumor survival and proliferation through facilitating the forming of an immunosuppressive tumor microenvironment and discuss the current advances of STING-related immunotherapies.

Understanding nucleic acid sensing and its therapeutic applications

Nucleic acid sensing is involved in viral infections, immune response-related diseases, and therapeutics. Based on the composition of nucleic acids, nucleic acid sensors are defined as DNA or RNA sensors. Pathogen-associated nucleic acids are recognized by membrane-bound and intracellular receptors, known as pattern recognition receptors (PRRs), which induce innate immune-mediated antiviral responses. PRR activation is tightly regulated to eliminate infections and prevent abnormal or excessive immune responses. Nucleic acid sensing is an essential mechanism in tumor immunotherapy and gene therapies that target cancer and infectious diseases through genetically engineered immune cells or therapeutic nucleic acids. Nucleic acid sensing supports immune cells in priming desirable immune responses during tumor treatment. Recent studies have shown that nucleic acid sensing affects the efficiency of gene therapy by inhibiting translation. Suppression of innate immunity induced by nucleic acid sensing through small-molecule inhibitors, virus-derived proteins, and chemical modifications offers a potential therapeutic strategy. Herein, we review the mechanisms and regulation of nucleic acid sensing, specifically covering recent advances. Furthermore, we summarize and discuss recent research progress regarding the different effects of nucleic acid sensing on therapeutic efficacy. This study provides insights for the application of nucleic acid sensing in therapy.

Immunotherapy combined with local therapy in the late-line treatment of repair-proficient (pMMR)/microsatellite stable (MSS) metastatic colorectal cancer

Colorectal cancer (CRC) is one of the most common malignancies, and at the initial visit, most patients are diagnosed with metastatic CRC (mCRC). However, immunotherapy is only and highly effective in a very small proportion of patients with mCRC having mismatch repair defect (dMMR)/high microsatellite instability, and the majority of the patients with mCRC having mismatch repair proficient (pMMR)/microsatellite stability (MSS) cannot benefit from it. At present, many clinical studies of immunotherapy combined with tyrosine kinase inhibitors (TKIs) are trying to regulate the immune microenvironment of pMMR/MSS mCRC, transforming a "cold tumor" into a "hot tumor," which has not only surprising effects but also certain limitations, i.e., the response could not be specific to metastasis. Therefore, regarding the bottleneck encountered by immunotherapy in patients with patients pMMR/MSS mCRC, this study summarized current research and possible mechanisms of immunotherapy combined with local therapy for metastasis, including radiotherapy, ablation, and transcatheter arterial chemoembolization.

The therapeutic potential of PD-1/PD-L1 pathway on immune-related diseases: Based on the innate and adaptive immune components

Currently, immunotherapy targeting programmed cell death 1 (PD-1) or programmed death ligand 1 (PD-L1) has revolutionized the treatment strategy of human cancer patients. Meanwhile, PD-1/PD-L1 pathway has also been implicated in the pathogenesis of many immune-related diseases, such as autoimmune diseases, chronic infection diseases and adverse pregnancy outcomes, by regulating components of the innate and adaptive immune systems. Given the power of the new therapy, a better understanding of the regulatory effects of PD-1/PD-L1 pathway on innate and adaptive immune responses in immune-related diseases will facilitate the discovery of novel biomarkers and therapeutic drug targets. Targeting this pathway may successfully halt or potentially even reverse these pathological processes. In this review, we discuss recent major advances in PD-1/PD-L1 axis regulating innate and adaptive immune components in immune-related diseases. We reveal that the impact of PD-1/PD-L1 axis on the immune system is complex and manifold and multi-strategies on the targeted PD-1/PD-L1 axis are taken in the treatment of immune-related diseases. Consequently, targeting PD-1/PD-L1 pathway, alone or in combination with other treatments, may represent a novel strategy for future therapeutic intervention on immune-related diseases.

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.

Combination Therapy of Immune Checkpoint Inhibitors with Locoregional Therapy for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is estimated to be the fourth leading cause of cancer-related deaths globally, and its overall prognosis is dismal because most cases are diagnosed at a late stage and are unamenable to curative treatment. The emergence of immune checkpoint inhibitors (ICIs) has dramatically improved the therapeutic efficacy for advanced hepatocellular carcinoma; however, their response rates remain unsatisfactory, partly because >50% of HCC exhibit an ICI-nonresponsive tumor microenvironment characterized by a paucity of cytotoxic T cells (immune-cold), as well as difficulty in their infiltration into tumor sites (immune excluded). To overcome this limitation, combination therapies with locoregional therapies, including ablation, transarterial embolization, and radiotherapy, which are usually used for early stage HCCs, have been actively explored to enhance ICI efficacy by promoting the release of tumor-associated antigens and cytokines, and eventually accelerating the so-called cancer-immunity cycle. Various combination therapies have been investigated in early- to late-phase clinical trials, and some have shown promising results. This comprehensive article provides an overview of the immune landscape for HCC to understand ICI efficacy and its limitations and, subsequently, reviews the status of combinatorial therapies of ICIs with locoregional therapy for HCC.

STING signaling activation modulates macrophage polarization via CCL2 in radiation-induced lung injury

BACKGROUND

Radiation-induced lung injury (RILI) is a prevalent complication of thoracic radiotherapy in cancer patients. A comprehensive understanding of the underlying mechanisms of RILI is essential for the development of effective prevention and treatment strategies.

METHODS

To investigate RILI, we utilized a mouse model that received 12.5 Gy whole-thoracic irradiation. The evaluation of RILI was performed using a combination of quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), histology, western blot, immunohistochemistry, RNA sequencing, and flow cytometry. Additionally, we established a co-culture system consisting of macrophages, lung epithelial cells, and fibroblasts for in vitro studies. In this system, lung epithelial cells were irradiated with a dose of 4 Gy, and we employed STING knockout macrophages. Translational examinations were conducted to explore the relationship between STING expression in pre-radiotherapy lung tissues, dynamic changes in circulating CCL2, and the development of RILI.

RESULTS

Our findings revealed significant activation of the cGAS-STING pathway and M1 polarization of macrophages in the lungs of irradiated mice. In vitro studies demonstrated that the deficiency of cGAS-STING signaling led to impaired macrophage polarization and RILI. Through RNA sequencing, cytokine profiling, and rescue experiments using a CCL2 inhibitor called Bindarit, we identified the involvement of CCL2 in the regulation of macrophage polarization and the development of RILI. Moreover, translational investigations using patient samples collected before and after thoracic radiotherapy provided additional evidence supporting the association between cGAS-STING signaling activity, CCL2 upregulation, and the development of radiation pneumonitis.

CONCLUSIONS

The cGAS-STING signaling pathway plays a crucial role in regulating the recruitment and polarization of macrophages, partly through CCL2, during the pathogenesis of RILI.

Infection, Inflammation, and Immunity in Sepsis

Sepsis is triggered by microbial infection, injury, or even major surgery. Both innate and adaptive immune systems are involved in its pathogenesis. Cytoplasmic presence of DNA or RNA of the invading organisms or damaged nuclear material (in the form of micronucleus in the cytoplasm) in the host cell need to be eliminated by various nucleases; failure to do so leads to the triggering of inflammation by the cellular cGAS-STING system, which induces the release of IL-6, TNF-α, and IFNs. These cytokines activate phospholipase A2 (PLA2), leading to the release of polyunsaturated fatty acids (PUFAs), gamma-linolenic acid (GLA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), which form precursors to various pro- and anti-inflammatory eicosanoids. On the other hand, corticosteroids inhibit PLA2 activity and, thus, suppress the release of GLA, AA, EPA, and DHA. PUFAs and their metabolites have a negative regulatory action on the cGAS-STING pathway and, thus, suppress the inflammatory process and initiate inflammation resolution. Pro-inflammatory cytokines and corticosteroids (corticosteroids > IL-6, TNF-α) suppress desaturases, which results in decreased formation of GLA, AA, and other PUFAs from the dietary essential fatty acids (EFAs). A deficiency of GLA, AA, EPA, and DHA results in decreased production of anti-inflammatory eicosanoids and failure to suppress the cGAS-STING system. This results in the continuation of the inflammatory process. Thus, altered concentrations of PUFAs and their metabolites, and failure to suppress the cGAS-STING system at an appropriate time, leads to the onset of sepsis. Similar abnormalities are also seen in radiation-induced inflammation. These results imply that timely administration of GLA, AA, EPA, and DHA, in combination with corticosteroids and anti-IL-6 and anti-TNF-α antibodies, may be of benefit in mitigating radiation-induced damage and sepsis.

Unleashing the efficacy of immune checkpoint inhibitors for advanced hepatocellular carcinoma: factors, strategies, and ongoing trials

Hepatocellular carcinoma (HCC) is a prevalent primary liver cancer, representing approximately 85% of cases. The diagnosis is often made in the middle and late stages, necessitating systemic treatment as the primary therapeutic option. Despite sorafenib being the established standard of care for advanced HCC in the past decade, the efficacy of systemic therapy remains unsatisfactory, highlighting the need for novel treatment modalities. Recent breakthroughs in immunotherapy have shown promise in HCC treatment, particularly with immune checkpoint inhibitors (ICIs). However, the response rate to ICIs is currently limited to approximately 15%-20% of HCC patients. Recently, ICIs demonstrated greater efficacy in "hot" tumors, highlighting the urgency to devise more effective approaches to transform "cold" tumors into "hot" tumors, thereby enhancing the therapeutic potential of ICIs. This review presented an updated summary of the factors influencing the effectiveness of immunotherapy in HCC treatment, identified potential combination therapies that may improve patient response rates to ICIs, and offered an overview of ongoing clinical trials focusing on ICI-based combination therapy.

Attenuated Salmonella carrying siRNA-PD-L1 and radiation combinatorial therapy induces tumor regression on HCC through T cell-mediated immuno-enhancement

Hepatocellular carcinoma (HCC), the most prevalent type of aggressive liver cancer, accounts for the majority of liver cancer diagnoses and fatalities. Despite recent advancements in HCC treatment, it remains one of the deadliest cancers. Radiation therapy (RT) is among the locoregional therapy modalities employed to treat unresectable or medically inoperable HCC. However, radioresistance poses a significant challenge. It has been demonstrated that RT induced the upregulation of programmed death ligand 1 (PD-L1) on tumor cells, which may affect response to PD-1-based immunotherapy, providing a rationale for combining PD-1/PD-L1 inhibitors with radiation. Here, we utilized attenuated Salmonella as a carrier to explore whether attenuated Salmonella carrying siRNA-PD-L1 could effectively enhance the antitumor effect of radiotherapy on HCC-bearing mice. Our results showed that a combination of siRNA-PD-L1 and radiotherapy had a synergistic antitumor effect by inhibiting the expression of PD-L1 induced by radiation therapy. Mechanistic insights indicated that the combination treatment significantly suppressed tumor cell proliferation, promoted cell apoptosis, and stimulated immune cell infiltration and activation in tumor tissues. Additionally, the combination treatment increased the ratios of CD4+ T, CD8+ T, and NK cells from the spleen in tumor-bearing mice. This study presents a novel therapeutic strategy for HCC treatment, especially for patients with RT resistance.

Mechanisms and applications of radiation-induced oxidative stress in regulating cancer immunotherapy

Radiotherapy (RT) is an effective treatment option for cancer patients, which induces the production of reactive oxygen species (ROS) and causes oxidative stress (OS), leading to the death of tumor cells. OS not only causes apoptosis, autophagy and ferroptosis, but also affects tumor immune response. The combination of RT and immunotherapy has revolutionized the management of various cancers. In this process, OS caused by ROS plays a critical role. Specifically, RT-induced ROS can promote the release of tumor-associated antigens (TAAs), regulate the infiltration and differentiation of immune cells, manipulate the expression of immune checkpoints, and change the tumor immune microenvironment (TME). In this review, we briefly summarize several ways in which IR induces tumor cell death and discuss the interrelationship between RT-induced OS and antitumor immunity, with a focus on the interaction of ferroptosis with immunogenic death. We also summarize the potential mechanisms by which ROS regulates immune checkpoint expression, immune cells activity, and differentiation. In addition, we conclude the therapeutic opportunity improving radiotherapy in combination with immunotherapy by regulating OS, which may be beneficial for clinical treatment.

Statins in Cancer Prevention and Therapy

Statins, a class of HMG-CoA reductase inhibitors best known for their cholesterol-reducing and cardiovascular protective activity, have also demonstrated promise in cancer prevention and treatment. This review focuses on their potential applications in head and neck cancer (HNC), a common malignancy for which established treatment often fails despite incurring debilitating adverse effects. Preclinical and clinical studies have suggested that statins may enhance HNC sensitivity to radiation and other conventional therapies while protecting normal tissue, but the underlying mechanisms remain poorly defined, likely involving both cholesterol-dependent and -independent effects on diverse cancer-related pathways. This review brings together recent discoveries concerning the anticancer activity of statins relevant to HNC, highlighting their anti-inflammatory activity and impacts on DNA-damage response. We also explore molecular targets and mechanisms and discuss the potential to integrate statins into conventional HNC treatment regimens to improve patient outcomes.

Combined radiotherapy and immune checkpoint inhibition for the treatment of advanced hepatocellular carcinoma

Hepatocellular Carcinoma (HCC) is one of the most common cancers and a leading cause of cancer related death worldwide. Until recently, systemic therapy for advanced HCC, defined as Barcelona Clinic Liver Cancer (BCLC) stage B or C, was limited and ineffective in terms of long-term survival. However, over the past decade, immune check point inhibitors (ICI) combinations have emerged as a potential therapeutic option for patients with nonresectable disease. ICI modulate the tumor microenvironment to prevent progression of the tumor. Radiotherapy is a crucial tool in treating unresectable HCC and may enhance the efficacy of ICI by manipulating the tumor microenvironment and decreasing tumor resistance to certain therapies. We herein review developments in the field of ICI combined with radiotherapy for the treatment of HCC, as well as look at challenges associated with these treatment modalities, and review future directions of combination therapy.

Molecular subtypes based on DNA sensors predict prognosis and tumor immunophenotype in hepatocellular carcinoma

DNA sensors play crucial roles in inflammation and have been indicated to be involved in antitumor or tumorigenesis, while it is still unclear whether DNA sensors have potential roles in the prognosis and immunotherapy of hepatocellular carcinoma (HCC). Herein, The Cancer Genome Atlas and Gene Expression Omnibus databases were used to analyze RNA sequencing data and clinical information. A total of 14 DNA sensors were collected and performed consensus clustering to determine their molecular mechanisms in HCC. Two distinct molecular subtypes (Clusters C1 and C2) were identified and were associated with different overall survival (OS). Immune subtype analysis revealed that C1 was mainly characterized by inflammation, while C2 was characterized by lymphocyte depletion. Immune scoring and immunomodulatory function analysis confirmed the different immune microenvironment of C1 and C2. Notably, significant differences in "Hot Tumor" Immunophenotype were observed between the two subtypes. Moreover, the prognostic model based on DNA sensors is capable of effectively predicting the OS of HCC patients. Besides, the chemotherapeutic drug analysis showed the different sensitivity of two subtypes. Taken together, our study shows that the proposed DNA sensors were a reliable signature to predict the prognosis and immunotherapy response with potential application in the clinical decision and treatment of HCC.

Molecular mechanisms of tumor resistance to radiotherapy

BACKGROUND

Cancer is the most prevalent cause of death globally, and radiotherapy is considered the standard of care for most solid tumors, including lung, breast, esophageal, and colorectal cancers and glioblastoma. Resistance to radiation can lead to local treatment failure and even cancer recurrence.

MAIN BODY

In this review, we have extensively discussed several crucial aspects that cause resistance of cancer to radiation therapy, including radiation-induced DNA damage repair, cell cycle arrest, apoptosis escape, abundance of cancer stem cells, modification of cancer cells and their microenvironment, presence of exosomal and non-coding RNA, metabolic reprogramming, and ferroptosis. We aim to focus on the molecular mechanisms of cancer radiotherapy resistance in relation to these aspects and to discuss possible targets to improve treatment outcomes.

CONCLUSIONS

Studying the molecular mechanisms responsible for radiotherapy resistance and its interactions with the tumor environment will help improve cancer responses to radiotherapy. Our review provides a foundation to identify and overcome the obstacles to effective radiotherapy.