Hypofractionated stereotactic radiation therapy activates the peripheral immune response in operable stage I non-small-cell lung cancer

The dynamic duo: A narrative review on the synergy between stereotactic body radiotherapy and immunotherapy in lung cancer treatment (Review)

Immunotherapy, particularly immune checkpoint inhibitors (ICIs), is undoubtedly one of the major breakthroughs in lung cancer research. Patient survival and prognosis have all been improved as a result, although numerous patients do not respond to immunotherapy due to various immune escape mechanisms of the tumor cells. Recent preclinical and clinical evidence has shown that stereotactic body radiotherapy (SBRT), also known as stereotactic ablative radiotherapy, has a prominent immune priming effect that could elicit antitumor immunity against specific tumor antigens and destroy distant tumor cells, thereby achieving the elusive abscopal effect, with the resulting immuno‑active tumor environment also being more conducive to ICIs. Some landmark trials have already demonstrated the survival benefit of the dynamic duo of SBRT plus immunotherapy in metastatic non‑small‑cell lung cancer, while others such as PEMBRO‑RT further suggest that the addition of SBRT to immunotherapy could expand the current indication to those who have historically responded poorly to ICIs. In the present review, the biological mechanisms that drive the synergistic effect of SBRT and immunotherapy were first briefly outlined; then, the current understanding from clinical trials was summarized and new insight into the evolving role of immunotherapy and SBRT synergy in lung cancer treatment was provided. Finally, novel avenues for discovery were highlighted. The innovation of the present review lies in the inclusion of non‑ICI immunotherapy in the discussion, which provides a more comprehensive view on the current development and future trend of SBRT + immunotherapy synergy.

Brachytherapy for high grade prostate cancer induces distinct changes in circulating CD4 and CD8 T cells - Implications for systemic control

This exploratory study is a follow up to our previous investigation of immune response in the circulation of high-grade Gleason 9 prostate cancer patients treated with EBRT + BT compared to EBRT alone. Notably, EBRT + BT demonstrates the potential to elicit an effect on CD4/CD8 ratio which may have attributed to improved clinical response to therapy. Our findings show promise for leveraging circulating immune cells as predictive biomarkers for radiotherapy response.

Modulation of CD8+ T Cell Responses by Radiotherapy-Current Evidence and Rationale for Combination with Immune Checkpoint Inhibitors

Radiotherapy for cancer has been known to affect the responses of immune cells, especially those of CD8+ T cells that play a pivotal role in anti-tumor immunity. Clinical success of immune checkpoint inhibitors led to an increasing interest in the ability of radiation to modulate CD8+ T cell responses. Recent studies that carefully analyzed CD8+ T cell responses following radiotherapy suggest the beneficial roles of radiotherapy on anti-tumor immunity. In addition, numerous clinical trials to evaluate the efficacy of combining radiotherapy with immune checkpoint inhibitors are currently undergoing. In this review, we summarize the current status of knowledge regarding the changes in CD8+ T cells following radiotherapy from various preclinical and clinical studies. Furthermore, key biological mechanisms that underlie such modulation, including both direct and indirect effects, are described. Lastly, we discuss the current evidence and essential considerations for harnessing radiotherapy as a combination partner for immune checkpoint inhibitors.

Modern Stereotactic Radiotherapy for Brain Metastases from Lung Cancer: Current Trends and Future Perspectives Based on Integrated Translational Approaches

Brain metastases (BMs) represent the most frequent metastatic event in the course of lung cancer patients, occurring in approximately 50% of patients with non-small-cell lung cancer (NSCLC) and in up to 70% in patients with small-cell lung cancer (SCLC). Thus far, many advances have been made in the diagnostic and therapeutic procedures, allowing improvements in the prognosis of these patients. The modern approach relies on the integration of several factors, such as accurate histological and molecular profiling, comprehensive assessment of clinical parameters and precise definition of the extent of intracranial and extracranial disease involvement. The combination of these factors is pivotal to guide the multidisciplinary discussion and to offer the most appropriate treatment to these patients based on a personalized approach. Focal radiotherapy (RT), in all its modalities (radiosurgery (SRS), fractionated stereotactic radiotherapy (SRT), adjuvant stereotactic radiotherapy (aSRT)), is the cornerstone of BM management, either alone or in combination with surgery and systemic therapies. We review the modern therapeutic strategies available to treat lung cancer patients with brain involvement. This includes an accurate review of the different technical solutions which can be exploited to provide a "state-of-art" focal RT and also a detailed description of the systemic agents available as effective alternatives to SRS/SRT when a targetable molecular driver is present. In addition to the validated treatment options, we also discuss the future perspective for focal RT, based on emerging clinical reports (e.g., SRS for patients with many BMs from NSCLC or SRS for BMs from SCLC), together with a presentation of innovative and promising findings in translational research and the combination of novel targeted agents with SRS/SRT.

Optimized CAR-T therapy based on spatiotemporal changes and chemotactic mechanisms of MDSCs induced by hypofractionated radiotherapy

Poor intratumoral infiltration is the major challenge for chimeric antigen receptor (CAR)-T cell therapy in solid tumors. Hypofractionated radiotherapy (HFRT) has been reported to induce immune cell infiltration and reshape the tumor immune microenvironment. Here, we showed that HFRT (5 × 5 Gy) mediated an early accumulation of intratumoral myeloid-derived suppressor cells (MDSCs) and decreased infiltration of T cells in the tumor microenvironment (TME) of immunocompetent mice bearing triple-negative breast cancer (TNBC) or colon cancer, which was further confirmed in tumors from patients. RNA sequencing (RNA-seq) and cytokine profiling analysis revealed that HFRT induced the activation and proliferation of tumor-infiltrated MDSCs, which was mediated by the interactions of multiple chemokines and chemokine receptors. Further investigation showed that when combined with HFRT, CXCR2 blockade significantly inhibited MDSCs trafficking to tumors and effectively enhanced the intratumoral infiltration and treatment efficacy of CAR-T cells. Our study demonstrates that MDSCs blockade combined with HFRT is promising for CAR-T cell therapy optimization in solid tumors.

Stereotactic Ablative Radiation Therapy in 3 Fractions Induces a Favorable Systemic Immune Cell Profiling in Prostate Cancer Patients

The impact of radiotherapy (RT) on immune cell status in prostate cancer (PCa) is only partially determined. The aim of this study was to assess the effect of different RT strategies on peripheral B, T, and Natural killer (NK) lymphocytes at precise longitudinal time-points in PCa. 18 patients treated with stereotactic body radiation therapy (SBRT) (40 Gy/3FRX), definitive moderate-hypofractionation (62 Gy/20FRX), or post-operative conventional-fractionation RT (66-69 Gy/30FRX) were prospectively evaluated for the immune cell profile in terms of immune cell composition, differentiation stage, cytokine production and inhibitory receptor (IR) expression. The immune-monitoring of the 18 patients revealed that RT affects the balance of systemic immune cells, with the main differences observed between SBRT and conventionally fractionated RT. SBRT favorably impacts immune response in term of increased B cells, central-memory and effector-memory CD8⁺ T cells, along with decreased Treg cells after treatment. On the contrary, conventional fractionated RT had a long-term negative effect on the systemic immune profile, including a decrease of total lymphocyte counts accompanied by an increase of neutrophils-to-lymphocytes ratio. Total B and T cells decreased and Treg-to-CD8⁺ ratio increased. Functionality of T lymphocytes were not affected by any of the 3-fractionation schedules. Interestingly, SBRT significantly up-regulates the expression of V-domain immunoglobulin suppressor of T-cell activation (VISTA) in CD8⁺ T cells in the absence of other IRs. Our results indicate the relevance of systematic immunomonitoring during RT to identify novel immune-related target to design trials of combined radio-immunotherapy as a promising strategy in the clinical management of PCa.

Tracking Peripheral Memory T Cell Subsets in Advanced Nonsmall Cell Lung Cancer Treated with Hypofractionated Radiotherapy and PD-1 Blockade

Hypofractionated radiotherapy (HFRT) or chemotherapy combined with programmed death-1 (PD-1) blockade has achieved good clinical control in advanced nonsmall cell lung cancer (NSCLC). However, the relative influence of HFRT + PD-1 blockade and chemo-immunotherapy on peripheral memory T cell subsets in NSCLC responders has not been evaluated in clinical practice. Thirty-nine patients with advanced NSCLC were enrolled. The frequencies of naive (Tn; CD45RA+CCR7+), central memory (Tcm; CD45RA–CCR7+), effector memory (Tem; CD45RA–CCR7–), and effector memory RA (TemRA; CD45RA+CCR7–) T cell subsets and PD-1 expression were analyzed in CD4+ and CD8+ T cells using flow cytometry from peripheral blood samples. The correlations of memory T cell subsets and PD-1 expression with overall survival in HFRT + PD-1 blockade group were examined using the Kaplan–Meier method. Patients with partial response to HFRT + PD-1 blockade showed reduction in Tn and expansion in TemRA cell subpopulations among CD8+ T cells and reduced PD-1+CD4+ and PD-1+CD8+ T cells, all of which were significantly correlated with overall survival. The responders to chemo-immunotherapy showed expansion of the TemRA and decrease of Tcm in CD8+ T cell subpopulation. Our findings show that HFRT+PD-1 blockade and chemo-immunotherapy combination therapies induce differential memory T cell subset differentiation, offering predictive markers for treatment response. Clinical Trial Information: https://clinicaltrials.gov/ct2/show/ChiCTR-1900027768.

Targeted Radiation and Immune Therapies-Advances and Opportunities for the Treatment of Prostate Cancer

Prostate cancer is the most diagnosed malignancy in men in the United States and the second leading cause of cancer-related death. For localized disease, radiation therapy is a standard treatment that is often curative. For metastatic disease, radiation therapy has been primarily used for palliation, however, several newer systemic radiation therapies have been demonstrated to significantly improve patient outcomes and improve survival. In particular, several targeted radionuclide therapies have been approved for the treatment of advanced-stage cancer, including strontium-89, samarium-153, and radium-223 for bone-metastatic disease, and lutetium-177-labeled PSMA-617 for patients with prostate-specific membrane antigen (PSMA)-expressing metastatic castration-resistant prostate cancer (mCRPC). Contrarily, immune-based treatments have generally demonstrated little activity in advanced prostate cancer, with the exception of the autologous cellular vaccine, sipuleucel-T. This has been attributed to the presence of an immune-suppressive prostate cancer microenvironment. The ability of radiation therapy to not only eradicate tumor cells but also potentially other immune-regulatory cells within the tumor immune microenvironment suggests that targeted radionuclide therapies may be well poised to combine with immune-targeted therapies to eliminate prostate cancer metastases more effectively. This review provides an overview of the recent advances of targeted radiation agents currently approved for prostate cancer, and those being investigated in combination with immunotherapy, and discusses the challenges as well as the opportunities in this field.

Pre-radiotherapy systemic immune inflammation index associated with overall survival in patients with advanced EGFR mutant non-small cell lung cancer receiving thoracic radiotherapy

PURPOSE

This study aimed to investigate the prognostic potential of the pre-radiotherapy systemic immune-inflammation index (SII) for the survival of advanced lung adenocarcinoma patients with epidermal growth factor receptor (EGFR) mutations, which might provide a basis for optimizing the comprehensive treatment scheme.

METHODS

A total of 111 lung adenocarcinoma patients with EGFR mutations, who received thoracic radiotherapy, were included in this retrospective study. The primary endpoint of the study was based on the overall survival (OS) of patients. The receiver operating characteristic (ROC) curve analysis was performed to determine the optimal cut-off value of each immune inflammation index. Kaplan-Meier analysis was performed for the comparison of OS. The Cox proportional-hazard model was used for the multivariate and univariate regression analyses to determine the correlations of prognostic factors with the disease.

RESULTS

SII was divided into the high SII group (≥ 620.2; 45.95%) and the low SII group (SII < 620.2; 54.05%) based on the optimal cutoff values. The median OS rates were 53.3 and 33.3 months in the low and high SII groups, respectively, showing statistically significant differences ( hazard ratio (HR) = 0.459; 95% CI 0.286-0.736; P < 0.001). The multivariate analysis showed that, after adjusting for the significant covariates, the SII values were independently associated with the improved OS of the patients (adjusted HR = 0.444; 95% CI 0.279-0.709; P = 0.001). The low NLR values were associated with the better OS of patients (HR = 0.509; 95% CI 0.326-0.792; P = 0.005) and vice versa (HR = 0.422; 95% CI 0.213-0.836; P < 0.001). The patients in the low LMR group before radiotherapy exhibited longer OS as compared to those in the high LMR group (HR = 0.497; 95% CI 0.308-0.802; P = 0.001).

CONCLUSIONS

This study showed that these inflammatory indices might have an important prognostic potential for advanced lung adenocarcinoma patients with EGFR mutations, receiving thoracic radiotherapy and might provide a basis for the individualized treatment of these patients.

Tumor Immune Microenvironment and Immunotherapy in Non-Small Cell Lung Cancer: Update and New Challenges

Non-small cell lung cancer (NSCLC) is a serious threat to the health of older adults. Despite the significant progress in immunotherapy, effective treatments for NSCLC remain limited. The development of tumors indicates failure in immune surveillance and the successful immune escape of tumor cells. Research on the tumor immune microenvironment (TIME) revealed these opposing immune processes and contributed to the discovery of new methods to suppress the immune escape and restore the immune surveillance functions. This paper aimed to provide updates on the current findings regarding the relevance of TIME in NSCLC treatment. It also aimed to introduce the TIME, immune editing, cancer immunotherapy, and new challenges. Based on the clinical data, the combination of neoadjuvant chemotherapy and immune checkpoint inhibitor (ICI) therapy is suitable for patients with NSCLC who are not eligible to undergo surgery. Combined ICI therapy after epidermal growth factor receptor (EGFR)/tyrosine kinase inhibitor (TKI) therapy should be considered in patients with EGFR mutations. Chemoradiotherapy may increase the density of CD8⁺ lymphocytes, which is significantly associated with better prognosis. For older patients and those with advanced-stage disease, regional tumor treatments, such as stereotactic radiation therapy and percutaneous cryoablation, may be more suitable, but further studies are needed to confirm this. In conclusion, restoring immune surveillance is as important as removing cancerous tissues; further studies that include the use of combined treatment methods, individualized treatment plans, and immunonutrition are warranted.

A Systematic Review on the Impact of Hypofractionated and Stereotactic Radiotherapy on Immune Cell Subpopulations in Cancer Patients

We investigated how hypofractionated radiotherapy (HFRT) and stereotactic body radiotherapy (SBRT) may impact immune cells in different type of tumors. A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The PubMed, Embase and Cochrane databases were searched. Overall, 11 studies met the inclusion criteria and were eligible for the present analysis. Both HFRT and SBRT have different impact on lymphocyte subpopulations, confirming their immunomodulatory effect which may have a crucial role in future combined treatment with new emergent therapies such as immunotherapy. Further studies are needed to shed more light on this emerging topic to ultimately improve patient care, treatment and clinical benefits for cancer patients.

Effect of stereotactic radiotherapy on immune microenvironment of lung cancer

Stereotactic radiotherapy (SRT) is one of the main treatment modalities for lung cancer, and the current SRT approach combined with immunotherapy has initially presented good clinical efficacy in lung cancer. SRT activates the immune system through in situ immunization, releasing antigens into the blood, which promotes the antigen–antibody response and then induces tumor cell apoptosis. Dose fractionation has different effects on the immune microenvironment, and the tumor microenvironment after SRT also changes over time, all of which have an impact on SRT combined immunotherapy. Although much research on the immune microenvironment of SRT has been conducted, many problems still require further exploration.

Systemic Immune Activation and Responses of Irradiation to Different Metastatic Sites Combined With Immunotherapy in Advanced Non-Small Cell Lung Cancer

Purpose

Considering the limited data, we aimed to identify the greatest immune activation irradiated site of common metastases and response to immune checkpoint inhibitors simultaneously in non-small cell lung cancer (NSCLC).

Methods

A total of 136 patients with advanced NSCLC who had received radiation to a primary or metastatic solid tumor were enrolled. We recorded blood cell counts in three time periods, before, during, and after radiotherapy (RT), and derived some blood index ratios including monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII). The delta-IBs were calculated as medio-IBs ÷ pre-IBs − 1. We analyzed the changes before and during RT using Spearman rank correlation test, Kruskal–Wallis rank sum test, and logistic regression analyzing their correlation with efficacy.

Results

The medians of delta-MLR and delta-PLR were both the lowest while the median of delta-L was the highest in brain. Therapeutic effect evaluation showed that the objective response rate (ORR) of 48.65% (18/37) in the brain irradiation group was the highest, compared with 17.07% (7/41) in bone and 41.94% (13/31) in lung.

Conclusions

In this study, results suggested that irradiation to brain has the best immune activation effect and patient outcome compared with other organs in NSCLC, and when the earlier-line ICIs were combined with RT, a better patient outcome was reached. Prospective studies are also necessary to provide more convincing evidence and standards for clinical irradiation metastases selection.

A Promising Treatment Strategy for Lung Cancer: A Combination of Radiotherapy and Immunotherapy

Lung cancer is a leading cause of cancer-related deaths worldwide despite advances in treatment. In the past few decades, radiotherapy has achieved outstanding technical advances and is being widely used as a definitive, prophylactic, or palliative treatment of patients with lung cancer. The anti-tumor effects of radiotherapy are considered to result in DNA damage in cancer cells. Moreover, recent evidence has demonstrated another advantage of radiotherapy: the induction of anti-tumor immune responses, which play an essential role in cancer control. In contrast, radiotherapy induces an immunosuppressive response. These conflicting reactions after radiotherapy suggest that maximizing immune response to radiotherapy by combining immunotherapy has potential to achieve more effective anti-tumor response than using each alone. Immune checkpoint molecules, such as cytotoxic T-lymphocyte-associated protein 4, programmed cell death-1/programmed death-ligand 1, and their inhibitors, have attracted significant attention for overcoming the immunosuppressive conditions in patients with cancer. Therefore, the combination of immune checkpoint inhibitors and radiotherapy is promising. Emerging preclinical and clinical studies have demonstrated the rationale for these combination strategies. In this review, we outlined evidence suggesting that combination of radiotherapy, including particle therapy using protons and carbon ions, with immunotherapy in lung cancer treatment could be a promising treatment strategy.

Biological Bases of Immune-Related Adverse Events and Potential Crosslinks With Immunogenic Effects of Radiation

Immune checkpoint inhibitors have gained an established role in the treatment of different tumors. Indeed, their use has dramatically changed the landscape of cancer care, especially for tumor types traditionally known to have poor outcomes. However, stimulating anticancer immune responses may also elicit an unusual pattern of immune-related adverse events (irAEs), different from those of conventional chemotherapy, likely due to a self-tolerance impairment featuring the production of autoreactive lymphocytes and autoantibodies, or a non-specific autoinflammatory reaction. Ionizing radiation has proven to promote both positive pro-inflammatory and immunostimolatory activities, and negative anti-inflammatory and immunosuppressive mechanisms, as a result of cross-linked interactions among radiation dose, the tumor microenvironment and the host genetic predisposition. Several publications argue in favor of combining immunotherapy and a broad range of radiation schedules, based on the recent evidence of superior treatment responses and patient survival. The synergistic modulation of the immune response by radiation therapy and immunotherapeutics, particularly those manipulating T-cell activation, may also affect the type and severity of irAEs, suggesting a relationship between the positive antitumor and adverse autoimmune effects of these agents. As yet, information on factors that may help to predict immune toxicity is still lacking. The aim of our work is to provide an overview of the biological mechanisms underlying irAEs and possible crosslinks with radiation-induced anticancer immune responses. We believe such an overview may support the optimization of immunotherapy and radiotherapy as essential components of multimodal anticancer therapeutic approaches. Challenges in translating these to clinical practice are discussed.

Combinations of Radiotherapy with Vaccination and Immune Checkpoint Inhibition Differently Affect Primary and Abscopal Tumor Growth and the Tumor Microenvironment

Radiotherapy (RT) is known to have immune-modulatory properties. We hypothesized that RT and inactivated whole tumor cell vaccines generated with high hydrostatic pressure (HHP) synergize to retard the tumor growth which can be additionally improved with anti-PD-1 treatment. In abscopal tumor models, we injected mice with B16-F10 melanoma or TS/A mammary tumors. To evaluate the efficiency of RT in combination with HHP vaccines, we locally irradiated only one tumor with 2 × 8 Gy or 3 × 8 Gy. HHP vaccines further retarded the growth of locally irradiated (2 × 8 Gy) tumors. However, HHP vaccination combined with RT failed to induce abscopal anti-tumor immune responses, namely those to non-irradiated tumors, and even partly abrogated those which were induced with RT plus anti-PD-1. In the latter group, the abscopal effects were accompanied by an elevated infiltration of CD8+ T cells, monocytes/macrophages, and dendritic cells. 3 × 8 Gy failed to induce abscopal effects in association with increased expression of immunosuppressive checkpoint molecules compared to 2 × 8 Gy. We conclude that HHP vaccines induce anti-tumor effects, but only if the tumor microenvironment was previously modulated by hypofractionated RT with not too many fractions, but failed to improve RT plus anti-PD-induced abscopal responses that are characterized by distinct immune alterations.

DNA Damage Baseline Predicts Resilience to Space Radiation and Radiotherapy

Deep space exploration will require real-time, minimally invasive monitoring of astronaut health to mitigate the potential health impairments caused by space radiation and microgravity. Genotoxic stress in humans can be monitored by quantifying the amount of DNA double-strand breaks (DSBs) in immune cells from a simple finger prick. In a cohort of 674 healthy donors, we show that the endogenous level of DSBs increases with age and with latent cytomegalovirus infection. To map the range of human responses to space radiation, we then study DSB induction and repair in immune cells from 319 healthy donors after the cells are exposed to galactic cosmic ray components and lymphocytes from 30 cancer patients after radiotherapy. Individuals with low baseline DSB have fewer clinical complications, enhanced DNA damage repair responses, and a functional dose-dependent cytokine response in healthy donor cells. This supports the use of DSB monitoring for health resilience in space.

Relationship between the invasion of lymphocytes and cytokines in the tumor microenvironment and the interval after single brachytherapy hypofractionated radiotherapy and conventional fractionation radiotherapy in non-small cell lung Cancer

Background

The effect of brachytherapy on lymphocytes and cytokines in the tumor microenvironment is unclear. This study aimed to analyze the relationship between the invasion of lymphocytes and cytokines in the tumor microenvironment and the interval after single brachytherapy hypofractionated radiotherapy (SBHFRT) and conventional fractionation radiotherapy (CFRT) in non-small cell lung cancer (NSCLC).

Methods

Lewis tumor-bearing mice were randomly divided into control, CFRT, and SBHFRT groups. On days 7 and 14 after radiation, the expression levels of CD86⁺, CD4⁺, CD8⁺, and Foxp3⁺ cells, and levels of Ki-67⁺ protein were detected by immunohistochemistry, and the tumor necrosis rate was calculated. Following this, the levels of interleukin-10 (IL-10), IL-12, and interferon-γ (IFN-γ) were detected by enzyme-linked immunosorbent assay. The apoptosis rate was evaluated via flow cytometry. The tumor volume and tumor growth inhibition rate (TGIR) were calculated on day 14. Tumor metabolism was assessed via 18F-FDG micropositron emission tomography/computer tomography.

Results

The tumor volume reduced by 22.0% and TGIR increased by 92.2% (p < 0.05) in the SBHFRT group. Further, on days 7 and 14 after radiation, tumor metabolism, Ki-67⁺ and Foxp3⁺ expression levels, and IL-10 levels were lower, and tumor necrosis and apoptosis rates; CD86⁺, CD4⁺, and CD8⁺ expression levels; and IL-12 and IFN-γ levels were higher in the SBHFRT group than in the CFRT group, particularly on day 7.

Conclusion

SBHFRT could lead to more accumulation of dendritic cells, anti-tumor lymphocytes, and cytokines, and further reduce the aggregation of immunosuppressive lymphocytes and cytokines in the tumor microenvironment compared with CFRT, and the difference was the most obvious on day 7 after radiation. The clinical significance of the findings remains to be further verified.

Enhancing the efficacy of immunotherapy using radiotherapy

Recent clinical breakthroughs in cancer immunotherapy, especially with immune checkpoint blockade, offer great hope for cancer sufferers - and have greatly changed the landscape of cancer treatment. However, whilst many patients achieve clinical responses, others experience minimal benefit or do not respond to immune checkpoint blockade at all. Researchers are therefore exploring multimodal approaches by combining immune checkpoint blockade with conventional cancer therapies to enhance the efficacy of treatment. A growing body of evidence from both preclinical studies and clinical observations indicates that radiotherapy could be a powerful driver to augment the efficacy of immune checkpoint blockade, because of its ability to activate the antitumor immune response and potentially overcome resistance. In this review, we describe how radiotherapy induces DNA damage and apoptosis, generates immunogenic cell death and alters the characteristics of key immune cells in the tumor microenvironment. We also discuss recent preclinical work and clinical trials combining radiotherapy and immune checkpoint blockade in thoracic and other cancers. Finally, we discuss the scheduling of immune checkpoint blockade and radiotherapy, biomarkers predicting responses to combination therapy, and how these novel data may be translated into the clinic.

A Clinician's Guide to Cancer-Derived Exosomes: Immune Interactions and Therapeutic Implications

Understanding of the role of immunity in the regulation of cancer growth continues to rapidly increase. This is fuelled by the impressive results yielded in recent years by immune checkpoint inhibitors, which block regulatory pathways to increase immune-mediated cancer destruction. Exosomes are cell-secreted membranous nanoscale vesicles that play important roles in regulating physiological and pathophysiological processes. Cancer-derived exosomes (CDEXs) and their biologically-active cargos have been proven to have varied effects in malignant progression, including the promotion of angiogenesis, metastasis, and favorable microenvironment modification. More recently, there is an increasing appreciation of their role in immune evasion. In addition to CDEXs, there are immune-derived exosomes that facilitate communication between immune cells in the non-malignant setting. Investigation of cancer-mediated mechanisms behind interruption or modification of these normal exosomal pathways may provide further understanding of how malignant immune evasion is accomplished. Accumulating evidence indicates that immune-active CDEXs also have the potential to impact clinical oncological management. Whilst immune checkpoint inhibitors have well-established pharmacologically-targeted pathways involving the immune system, other widely used treatments such as radiation and cytotoxic chemotherapies do not. Thus, investigating exosomes in immunotherapy is important for the development of next-generation combination therapies. In this article, we review the ways in which CDEXs impact individual immune cell types and how this contributes to the development of immune evasion. We discuss the relevance of lymphocytes and myeloid-lineage cells in the control of malignancy. In addition, we highlight the ways that CDEXs and their immune effects can impact current cancer therapies and the resulting clinical implications.

Radiation-induced small extracellular vesicles as "carriages" promote tumor antigen release and trigger antitumor immunity

Rationale: Accumulating evidence supports the importance of radiation therapy in the induction of antitumor immunity. Small extracellular vesicles (sEVs) play essential roles in tumor antigen loading and delivery. However, the role of sEVs in radiation-induced antitumor immunity remains unclear. It is therefore important to determine the role and regulatory mechanisms of sEVs in radiation-induced immunity.

Methods: Tumor cells were irradiated (8 Gy), and sEVs were purified via ultracentrifugation. Primary tumor and experimental lung metastasis models were established in mice to evaluate antitumor immunity triggered by immunization with sEVs. Proteomic and bioinformatic analyses were performed to identify altered cargos in sEVs induced by radiation. Peptides derived from up-regulated proteins in sEVs were designed and synthesized as vaccines according to major histocompatibility complex (MHC) I binding and immunogenicity.

Results: Here, we demonstrated that sEVs derived from irradiated tumor cells could trigger antitumor immunity against primary tumor and experimental lung metastasis by enhancing CD8⁺ and CD4⁺ T cell infiltration. Radiation may also enrich sEVs with tumor antigens and heat-shock proteins. Furthermore, CUB domain-containing protein 1 (CDCP1) derived from radiation-induced sEVs was identified as a novel tumor-associated antigen and developed as a peptide vaccine that may generate antitumor immune responses.

Conclusions: Our results demonstrate that the use of sEVs secreted by irradiated tumor cells constitutes an efficient approach for tumor antigen delivery and presentation and highlight the role of sEVs in radiation-triggered antitumor immunity.

Depleting tumor-associated Tregs via nanoparticle-mediated hyperthermia to enhance anti-CTLA-4 immunotherapy

Aim: We aim to demonstrate that a local nanoparticle-mediated hyperthermia can effectively eliminate tumor-associated Tregs and thereby boost checkpoint blockade-based immunotherapy. Materials & methods: Photothermal therapy (PTT), mediated with systemically administered stealthy iron-oxide nanoparticles, was applied to treat BALB/c mice bearing 4T1 murine breast tumors. Flow cytometry was applied to evaluate both Treg and CD8+ T-cell population. Tumor growth following combination therapy of both PTT and anti-CTLA-4 was further evaluated. Results: Our data reveal that tumor-associated Tregs can be preferentially depleted via iron-oxide nanoparticles-mediated PTT. When combining PTT with anti-CTLA-4 immunotherapy, we demonstrate a significant inhibition of syngeneic 4T1 tumor growth. Conclusion: This study offers a novel strategy to overcome Treg-mediated immunosuppression and thereby to boost cancer immunotherapy.

Is the Combination of Immunotherapy and Radiotherapy in Non-small Cell Lung Cancer a Feasible and Effective Approach?

For many years, conventional oncologic treatments such as surgery, chemotherapy, and radiotherapy (RT) have dominated the field of non-small-cell lung cancer (NSCLC). The recent introduction of immunotherapy (IT) in clinical practice, especially strategies targeting negative regulators of the immune system, so-called immune checkpoint inhibitors, has led to a paradigm shift in lung cancer as in many other solid tumors. Although antibodies against programmed death protein-1 (PD-1) and programmed death ligand-1 (PD-L1) are currently on the forefront of the immuno-oncology field, the first efforts to eradicate cancer by exploiting the host's immune system date back to several decades ago. Even then, researchers aimed to explore the addition of RT to IT strategies in NSCLC patients, attributing its potential benefit to local control of target lesions through direct and indirect DNA damage in cancer cells. However, recent pre-clinical and clinical data have shown RT may also modify antitumor immune responses through induction of immunogenic cell death and reprogramming of the tumor microenvironment. This has led many to reexamine RT as a partner therapy to immuno-oncology treatments and investigate their potential synergy in an exponentially growing number of clinical trials. Herein, the authors review the rationale of combining IT and RT across all NSCLC disease stages and summarize both historical and current clinical evidence surrounding these combination strategies. Furthermore, an overview is provided of active clinical trials exploring the IT-RT concept in different settings of NSCLC.

A translational concept of immuno-radiobiology

BACKGROUND

Traditional concepts of radiobiology model the direct radiation-induced cellular cytotoxicity but are not focused on late and sustained effects of radiation. Recent experimental data show the close involvement of immunological processes.

METHODS

Based on systematic PubMed searches, experimental data on immunological radiation effects are summarized and analyzed in a non-quantitative descriptive manner to provide a translational perspective on the immuno-modulatory impact of radiation in cancer.

RESULTS

Novel experimental findings document that sustained radiation effects are ultimately mediated through systemic factors such as cytotoxic CD8+ T cells and involve a local immuno-stimulation. Increased tumor infiltration of CD8+ T cell is a prerequisite for long-term radiation effects. CD8+ T cell depletion induces radio-resistance in experimental tumors. The proposed sequence of events involves radiation-damaged cells that release HMGB1, which activates macrophages via TLR4 to a local immuno-stimulation via TNF, which contributes to maturation of DCs. The mature DCs migrate to lymph nodes where they trigger effective CD8+ T cell responses. Radiation effects are boosted, when the physiological self-terminating negative feedback of immune reactions is antagonised via blocking of TGF-β or via checkpoint inhibition with involvement of CD8+ T cells as common denominator.

CONCLUSION

The concept of immuno-radiobiology emphasizes the necessity for a functional integrity of APCs and T cells for the long-term effects of radiotherapy. Local irradiation at higher doses induces tumor infiltration of CD8+ T cells, which can be boosted by immunotherapy. More systematic research is warranted to better understand the immunological effects of escalating radiation doses.

Tumor microenvironment modulation enhances immunologic benefit of chemoradiotherapy

BACKGROUND

Chemoradiotherapy (CRT) remains one of the most common cancer treatment modalities, and recent data suggest that CRT is maximally effective when there is generation of an anti-tumoral immune response. However, CRT has also been shown to promote immunosuppressive mechanisms which must be blocked or reversed to maximize its immune stimulating effects.

METHODS

Therefore, using a preclinical model of human papillomavirus (HPV)-associated head and neck squamous cell carcinoma (HNSCC), we developed a clinically relevant therapy combining CRT and two existing immunomodulatory drugs: cyclophosphamide (CTX) and the small molecule inducible nitric oxide synthase (iNOS) inhibitor L-n6-(1-iminoethyl)-lysine (L-NIL). In this model, we treated the syngeneic HPV-HNSCC mEER tumor-bearing mice with fractionated (10 fractions of 3 Gy) tumor-directed radiation and weekly cisplatin administration. We compared the immune responses induced by CRT and those induced by combinatory treatment (CRT + CTX/L-NIL) with flow cytometry, quantitative multiplex immunofluorescence and by profiling immune-related gene expression changes.

RESULTS

We show that combination treatment favorably remodels the tumor myeloid immune microenvironment including an increase in anti-tumor immune cell types (inflammatory monocytes and M1-like macrophages) and a decrease in immunosuppressive granulocytic myeloid-derived suppressor cells (MDSCs). Intratumoral T cell infiltration and tumor antigen specificity of T cells were also improved, including a 31.8-fold increase in the CD8+ T cell/ regulatory T cell ratio and a significant increase in tumor antigen-specific CD8+ T cells compared to CRT alone. CTX/LNIL immunomodulation was also shown to significantly improve CRT efficacy, leading to rejection of 21% established tumors in a CD8-dependent manner.

CONCLUSIONS

Overall, these data show that modulation of the tumor immune microenvironment with CTX/L-NIL enhances susceptibility of treatment-refractory tumors to CRT. The combination of tumor immune microenvironment modulation with CRT constitutes a translationally relevant approach to enhance CRT efficacy through enhanced immune activation.

SMAC Mimetic Debio 1143 and Ablative Radiation Therapy Synergize to Enhance Antitumor Immunity against Lung Cancer

PURPOSE

Adaptive antitumor immunity following ablative radiotherapy (ART) is attenuated by host myeloid-derived suppressor cell (MDSC), tumor-associated macrophage (TAM), and regulatory T-cell (Treg) infiltrates. We hypothesized treatment with ART and a secondary mitochondrial-derived activators of caspase (SMAC) mimetic could reverse the immunosuppressive lung cancer microenvironment to favor adaptive immunity.

EXPERIMENTAL DESIGN

To evaluate for synergy between ART and the SMAC mimetic Debio 1143 and the dependence upon CD8⁺ T cells and TNFα, we used LLC-OVA syngeneic mouse model of lung cancer and treated them with Debio 1143 and/or ART (30 Gy) with or without anti-CD8, anti-TNFα, or anti-IFNγ antibodies. Tumor-infiltrating OVA-specific CD8⁺ T cells, Tc1 effector cells, MDSCs, TAMs, and Tregs, were quantified by flow cytometry. Tc1-promoting cytokines TNFα, IFNγ, and IL1β and the immunosuppressive IL10 and Arg-1 within LLC-OVA tumor tissue or mouse serum were measured by RT-PCR and ELISA.

RESULTS

ART delayed tumor growth, and the addition of Debio 1143 greatly enhanced its efficacy, which included several complete responses. These complete responders rejected an LLC-OVA tumor rechallenge. ART and Debio 1143 synergistically induced a tumor-specific, Tc1 cellular and cytokine response while eliminating immunosuppressive cells and cytokines from the tumor microenvironment. Depletion of CD8⁺ cells, TNFα, and IFNγ with blocking antibody abrogated synergy between ART and Debio 1143 and partially restored tumor-infiltrating MDSCs.

CONCLUSIONS

Debio 1143 augments the tumor-specific adaptive immunity induced by ART, while reversing host immunosuppressive cell infiltrates in the tumor microenvironment in a TNFα, IFNγ, and CD8⁺ T-cell-dependent manner. This provides a novel strategy to enhance the immunogenicity of ART.

Expression and correlation of MALAT1 and SOX9 in non-small cell lung cancer

INTRODUCTION

Non-small cell lung cancer (NSCLC) is the most common cause of cancer-related deaths in the world. MALAT1 and SOX9 have important roles in tumour formation and development in several types of cancers. However, little is known about the function and co-relationship of these 2 factors in NSCLC in vivo.

OBJECTIVES

To explore the role of MALAT1 and SOX9 expression relationship, their clinical pathological characteristics and OS on NSCLC patients.

METHODS

Paired of primary lung cancer tissues and the matched tumour adjacent tissues were collected in 121 NSCLC patients. MALAT1 and SOX9 mRNA expression was measured by SYBR green q RT-PCR assay. SOX-9 protein expression was measured by streptavidin-peroxidase (SP) staining method.

RESULTS

MALAT1and SOX9 expression was higher in NSCLC tissues than the adjacent tissues, and they have positive correlation. Moreover, SOX9 protein expression was higher in NSCLC tissues, especially in MALAT1 mRNA higher expressed NSCLC tissues. MALAT1 and SOX9 mRNA expression were associated with age (x² =11.474, P = .009), tumour size (x² =26.839, P = .000), TNM stage (x² =8.010, P = .046) and LEL. (x² =53.908, P = .000). NSCLC patients with higher MALAT1 and SOX9 mRNA expression had poorer OS rates.

CONCLUSIONS

MALAT1 and SOX9 could be used as prognostic co-biomarker in NSCLC.

Combination Cancer Therapy with Immune Checkpoint Blockade: Mechanisms and Strategies

The success of immune checkpoint blockade in patients with a wide variety of malignancies has changed the treatment paradigm in oncology. However, combination therapies with immune checkpoint blockade will be needed to overcome resistance and broaden the clinical utility of immunotherapy. Here we discuss a framework for rationally designing combination therapy strategies based on enhancing major discriminatory functions of the immune system that are corrupted by cancer-namely, antigenicity, adjuvanticity, and homeostatic feedback inhibition. We review recent advances on how conventional genotoxic cancer therapies, molecularly targeted therapies, epigenetic agents, and immune checkpoint inhibitors can restore these discriminatory functions. Potential barriers that can impede response despite combination therapy are also discussed.