Radiation-induced immune responses: mechanisms and therapeutic perspectives

In-Depth Analysis of the Necessity and Optimization Strategies for Adjuvant Radiotherapy Following Neoadjuvant Immunotherapy in the New Era of Esophageal Cancer Treatment

As immunotherapy rises to prominence in cancer treatment, the therapeutic approach to esophageal cancer is undergoing significant transformations. This review emphasizes the necessity and optimization pathways for adjuvant postoperative radiotherapy after neoadjuvant therapy in patients with esophageal cancer in the immunotherapy era. Initially, we review the advancements in neoadjuvant treatment strategies. Subsequently, we evaluate the role of postoperative radiotherapy and the latest advancements in radiotherapy target volume definition and dose optimization following neoadjuvant therapy, as well as the implications of tumor immunotherapy on postoperative radiotherapy strategies. In conclusion, in the new era of immunotherapy, postoperative radiotherapy following neoadjuvant therapy for esophageal cancer holds significant value. Optimization strategies should follow individualized treatment principles and comprehensively consider tumor biology, patient status, and treatment resources to achieve optimal therapeutic outcomes and quality of life, thereby driving continuous innovation in esophageal cancer treatment.

Zinc as an adjunct in radiation-based therapies: Evidences of radioprotection and mechanistic insights

BackgroundRadiation-based therapies are a progressive modality for managing life-threatening diseases such as cancer. However, these treatments often inflict damage on non-target tissues, necessitating the development of effective radioprotective agents. Zinc, known for its diversified role under various pathological conditions, has emerged as a potential protective agent against radiation-induced injuries due to its antioxidant, anti-inflammatory and immune-regulating properties.AimThis review aims to evaluate the potential of zinc in mitigating the adverse effects associated with radiation-based therapies, focusing on its protective role in normal tissue injury.MethodsA comprehensive literature review was conducted using multiple databases, including PubMed, NCBI, SciFinder, Google Scholar and Science Direct. Relevant studies assessing the radioprotective effects of zinc were identified and analysed to summarise its efficacy and potential benefits in radiation therapy.ResultsThe review highlights the beneficial effects of zinc in managing radiation-induced adverse effects, such as oral mucositis, skin injury, dermatitis, xerostomia, dysgeusia, dysosmia, bone marrow regeneration and oxidative stress reduction. Zinc's role as an antioxidant and anti-inflammatory agent, along with its ability to regulate immune system homeostasis, underpins these protective effects.ConclusionsZinc shows promising potential as a radioprotective agent in mitigating the adverse effects of radiation-based therapies. Despite the positive preclinical and clinical findings, further randomised trials with larger sample sizes and rigorous methodologies are needed to confirm zinc's efficacy. Additionally, further research is warranted to explore zinc's potential in addressing other radiation-induced events, ultimately contributing to improved patient care during radiation therapy.

PCR-based detection technique and gamma irradiation strategies for managing Ralstonia solanacearum-induced brown rot of potato

PURPOSE

The study focused on developing a rapid PCR-based detection method and employing gamma irradiation techniques to manage Ralstonia solanacearum, aiming to produce brown rot-free export-quality potatoes. This initiative seeks to enhance potato exports from Bangladesh.

MATERIALS AND METHODS

Samples of potato tubers and soil were collected from various commercially significant potato-growing areas, resulting in a total of 168 Ralstonia solanacearum isolates from potato tubers and soil across 12 regions. The detection of R. solanacearum in the enriched tuber extract and soil were conducted using the primer pairs (PS-1, PS-2) and (759, 760). For the gamma irradiation experiment, petri dishes containing R. solanacearum cultures were subjected to different doses of gamma rays at the Bangladesh Institute of Nuclear Agriculture using a 60Co source. The irradiation doses applied to the samples were 0-6.0KGy.

RESULTS

Morphological identification based on pink/light red colonies on TTC medium was confirmed R. solanacearum in 148 isolates. PCR using species-specific primers (PS-1/PS-2) and (759, 760) verified 26 isolates (14 tubers, 12 soil), producing 553 bp and 281 bp fragments in latently infected tubers and soil samples respectively. Gamma irradiation at 2.5 kGy damaged R. solanacearum's DNA and cells, preventing brown rot, while higher doses eliminated it entirely. This offers a promising strategy to enhance safety of stored potatoes, potentially mitigating economic losses from this quarantine pathogen.

CONCLUSION

The study developed a PCR detection method and gamma irradiation techniques to manage R. solanacearum, enhancing the export quality of potatoes.

Convection-enhanced delivery of [177Lu]Lu-labeled gold nanoparticles combined with anti-PD1 checkpoint immunotherapy improves the survival of immunocompetent C57BL/6J mice with orthotopic GL261 murine glioma tumors

INTRODUCTION

Our objective was to study convection enhanced delivery (CED) of 177Lu-labeled metal chelating polymer (MCP) conjugated to gold nanoparticles ([177Lu]Lu-MCP-AuNP) alone or combined with anti-PD1 immune checkpoint inhibition (ICI) for improving the survival of immunocompetent C57BL/6J mice with orthotopic GL261 murine glioma tumors.

METHODS

C57BL/6J mice with GL261 tumors were treated with [177Lu]Lu-MCP-AuNP (0.8 or 2.7 MBq; 4 × 1011 AuNP) alone or combined with anti-PD1 antibodies (200 μg i.p. every 2 d × 3 doses). Control mice received normal saline, non-radioactive MCP-AuNP or anti-PD1 antibodies. Kaplan-Meier median survival was estimated. T-cell infiltration into the brain was probed by flow cytometry. Toxicity was assessed by monitoring body weight and cognitive function tests [Object Location Test (OLT) and Novel Object Recognition Test (NORT)] and T2-weighted MRI of the brain, overall health and ex vivo histopathological examination of the brain.

RESULTS

Treatment with [177Lu]Lu-MCP-AuNP (0.8 MBq) significantly increased median survival compared to MCP-AuNP (29 vs. 25 d; P = 0.007) or normal saline-treated mice (24 d; P < 0.001). Combining [177Lu]Lu-MCP-AuNP (0.8 MBq) with anti-PD1 antibodies increased median survival to 32 d (P < 0.0001 vs. normal saline). Increasing the mean amount of [177Lu]Lu-MCP-AuNP to 2.7 MBq and combining with anti-PD1 antibodies extended survival to at least 218 d in 5/9 mice. Increased CD8+ cytotoxic T-cells and decreased CD4+ helper T-cells were found in the brain vs. normal saline-treated mice. No weight loss (>20 %) was observed for treated or control mice. There was no change in cognitive function in mice treated with [177Lu]Lu-MCP-AuNP (0.8 MBq) alone or combined with anti-PD1 antibodies assessed by the OLT or NORT. T2-weighted MRI in mice treated with 2.7 MBq [177Lu]Lu-MCP-AuNP combined with anti-PD1 antibodies revealed edema, gliosis and ex vacuo dilatation of the ventricle proximal to the site of infusion. Histopathological examination of the brain revealed dilatation of the ventricle and gliosis proximal to the site of infusion but no radiation necrosis. MRI and histological analysis did not reveal tumor in the brain of these mice. Mice treated with 2.7 MBq [177Lu]Lu-MCP-AuNP combined with anti-PD1 antibodies did not demonstrate overall deleterious health effects.

CONCLUSIONS

We conclude that CED of [177Lu]Lu-MCP-AuNP combined with anti-PD1 checkpoint immunotherapy improved the survival of immunocompetent C67BL/6J mice with GL261 glioma tumors in the brain. Higher administered amounts of [177Lu]Lu-MCP-AuNP (2.7 MBq vs. 0.8 MBq) were most effective and yielded long-term survival.

ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE

This study demonstrates that combining a locally-infused radiation nanomedicine, [177Lu]Lu-MCP-AuNP and anti-PD1 checkpoint immunotherapy improved the survival of mice with glioma tumors in the brain. In the future, this treatment may be useful to treat residual tumor at the surgical margins in patients with GBM to prevent local recurrence and improve survival.

Environmental Low-Dose Radiation Activates Th1 Immunity through the Mitochondria-STING Pathway

The presence of low-dose radiation (LDR) in the environment has become more prevalent. However, the effect of LDR exposure on the immune system remains elusive. Here, we interestingly found that LDR specifically elevated the percentage of CD4+IFNγ+ Th1 splenocytes, both in vitro and in vivo, without affecting the percentage of CD8+IFNγ+ Tc1 cells and regulatory T cells. A similar phenomenon was found in T cells from peripheral blood. Mechanistically, we found that LDR can induce mitochondrial damage, which stimulated the STING signaling pathway, leading to the enhanced expression of T-bet, the master transcriptional factor of Th1-cell differentiation. The specific STING signal inhibitor can abrogate the effect of LDR on Th1 differentiation, confirming the central role of the STING pathway. To further validate the immunoregulatory role of LDR, we exposed mice with whole body LDR and evaluated if LDR could protect mice against triple-negative breast cancer through enhanced antitumor immunity. As expected, LDR significantly delayed tumor development and promoted cell death. Meanwhile, LDR resulted in increased tumor-infiltrating Th1 cells, while the proportion of Tc1 and Treg cells remained unchanged. Furthermore, the infiltration of antitumor macrophages was also increased. In summary, we revealed that environmental LDR could specifically regulate Th1 T-cell activities, providing critical information for the potential application of LDR in both clinical and nonclinical settings.

Advancements in a novel model of autophagy and immune network regulation in radioresistance of cancer stem cells

Radiotherapy, a precise modality for treating malignant tumors, has undergone rapid advancements in primary and clinical research. The mechanisms underlying tumor radioresistance have become significant research. With the introduction and in-depth study of cancer stem cells (CSCs) theory, CSCs have been identified as the primary factor contributing to the development of tumor radioresistance. The "stemness" of CSCs is a biological characteristic of a small subset of cells within tumor tissues, characterized by self-renewal solid ability. This characteristic leads to resistance to radiotherapy, chemotherapy, and targeted therapies, driving tumor recurrence and metastasis. Another study revealed that cellular autophagy plays a pivotal role in maintaining the "stemness" of CSCs. Autophagy is a cellular mechanism that degrades proteins and organelles to generate nutrients and energy in response to stress. This process maintains cellular homeostasis and contributes to CSCs radioresistance. Furthermore, ionizing radiation (IR) facilitates epithelial-to-mesenchymal transition (EMT), vascular regeneration, and other tumor processes by influencing the infiltration of M2-type tumor-associated macrophages (TAMs). IR promotes the activation of the classical immunosuppressive "switch," PD-1/PD-L1, which diminishes T-cell secretion, leading to immune evasion and promoting radioresistance. Interestingly, recent studies have found that the immune pathway PD-1/PD-L1 is closely related to cellular autophagy. However, the interrelationships between immunity, autophagy, and radioresistance of CSCs and the regulatory mechanisms involved remain unclear. Consequently, this paper reviews recent research to summarize these potential connections, aiming to establish a theoretical foundation for future studies and propose a new model for the network regulation of immunity, autophagy, and radioresistance of tumor cells.

Abscopal effect: from a rare phenomenon to a new frontier in cancer therapy

Radiotherapy (RT) controls local lesions, meantime it has the capability to induce systemic response to inhibit distant, metastatic, non-radiated tumors, which is referred to as the "abscopal effect". It is widely recognized that radiotherapy can stimulate systemic immune response. This provides a compelling theoretical basis for the combination of immune therapy combined with radiotherapy(iRT). Indeed, this phenomenon has also been observed in clinical treatment, bringing significant clinical benefits to patients, and a series of basic studies are underway to amplify this effect. However, the molecular mechanisms of immune response induced by RT, determination of the optimal treatment regimen for iRT, and how to amplify the abscopal effect. In order to amplify and utilize this effect in clinical management, these key issues require to be well addressed; In this review, we comprehensively summarize the growing consensus and emphasize the emerging limitations of enhancing the abscopal effect with radiotherapy or immunotherapy. Finally, we discuss the prospects and barriers to the current clinical translational applications.

Citicoline modulates inflammatory signaling pathways in the spleen of rats exposed to gamma-radiation

BACKGROUND AND AIM

The spleen has an essential role in immune responses regulation and is considered the biggest peripheral immune organ. Citicoline is used for various brain disorders management. This study aimed to examine the using possibility of citicoline to treat γ-radiation-induced splenic inflammation in rats.

MATERIALS AND METHODS

Eighteen male albino rats were classified into: Group 1 (control) animals were kept as control. Group 2 (γ-radiation) animals were total-body γ-irradiated with 6 Gy. Group 3 (γ-radiation + citicoline) rats were γ-irradiated with 6 Gy, then injected intraperitoneally with citicoline (300 mg/kg/d) 5 min after irradiation for one week. Levels of TNF-α, IL-1β, iNOS, NF-κB, JAK2, and STAT3 were determined in spleen tissue, along with histopathological examination.

RESULTS

Rats exposure to gamma-radiation led to elevation in splenic TNF-α, IL-1β, NF-κB, iNOS, JAK2, and STAT3 levels significantly. Treatment with citicoline after gamma-radiation exposure improved this elevation, and modulated gamma-radiation-induced histopathological alterations.

CONCLUSIONS

This data showed that citicoline inhibited γ-radiation-induced splenic inflammation via suppressing NF-κB and JAK2/STAT3 signaling pathways in spleen tissue.

Natural Guardians: Natural Compounds as Radioprotectors in Cancer Therapy

Cancer remains a significant global health challenge, with millions of deaths attributed to it annually. Radiotherapy, a cornerstone in cancer treatment, aims to destroy cancer cells while minimizing harm to healthy tissues. However, the harmful effects of irradiation on normal cells present a formidable obstacle. To mitigate these effects, researchers have explored using radioprotectors and mitigators, including natural compounds derived from secondary plant metabolites. This review outlines the diverse classes of natural compounds, elucidating their roles as protectants of healthy cells. Furthermore, the review highlights the potential of these compounds as radioprotective agents capable of enhancing the body's resilience to radiation therapy. By integrating natural radioprotectors into cancer treatment regimens, clinicians may improve therapeutic outcomes while minimizing the adverse effects on healthy tissues. Ongoing research in this area holds promise for developing complementary strategies to optimize radiotherapy efficacy and enhance patient quality of life.

Nintedanib Mitigates Radiation-Induced Pulmonary Fibrosis by Suppressing Epithelial Cell Inflammatory Response and Inhibiting Fibroblast-to-Myofibroblast Transition

Radiation-induced pulmonary fibrosis (RIPF) represents a serious complication observed in individuals undergoing thoracic radiation therapy. Currently, effective interventions for RIPF are unavailable. Prior research has demonstrated that nintedanib, a Food and Drug Administration (FDA)-approved anti-fibrotic agent for idiopathic pulmonary fibrosis, exerts therapeutic effects on chronic fibrosing interstitial lung disease. This research aimed to investigate the anti-fibrotic influences of nintedanib on RIPF and reveal the fundamental mechanisms. To assess its therapeutic impact, a mouse model of RIPF was established. The process involved nintedanib administration at various time points, both prior to and following thoracic radiation. In the RIPF mouse model, an assessment was conducted on survival rates, body weight, computed tomography features, histological parameters, and changes in gene expression. In vitro experiments were performed to discover the mechanism underlying the therapeutic impact of nintedanib on RIPF. Treatment with nintedanib, administered either two days prior or four weeks after thoracic radiation, significantly alleviated lung pathological changes, suppressed collagen deposition, and improved the overall health status of the mice. Additionally, nintedanib demonstrated significant mitigation of radiation-induced inflammatory responses in epithelial cells by inhibiting the PI3K/AKT and MAPK signaling pathways. Furthermore, nintedanib substantially inhibited fibroblast-to-myofibroblast transition by suppressing the TGF-β/Smad and PI3K/AKT/mTOR signaling pathways. These findings suggest that nintedanib exerts preventive and therapeutic effects on RIPF by modulating multiple targets instead of a single anti-fibrotic pathway and encourage the further clinical trials to determine the efficacy of nintedanib in patients with RIPF.

Clinical significance of the advanced lung cancer inflammation index in patients with limited-stage small cell lung cancer treated with chemoradiotherapy

The aim of the study was to investigate the prognostic significance of the advanced lung cancer inflammation index (ALI) in patients with limited-stage small-cell lung cancer (LS-SCLC) undergoing definite chemo-radiotherapy (CRT). We included 87 patients with LS-SCLC from South Korea, treated between 2005 and 2019 with definite CRT. ALI was calculated using body mass index, serum albumin, and neutrophil-lymphocyte ratio. We categorized 38 patients into the high ALI group (ALI ≥ 44.3) and 48 into the low ALI group (ALI < 44.3). Patients in the high ALI group exhibited longer overall survival (OS) than patients in the low ALI group. In multivariate analysis, prophylactic cranial irradiation (hazard ratio [HR] = 0.366, 95% confidence interval [CI] 0.20-0.66, P = 0.0008), and high ALI (HR = 0.475, 95% CI 0.27-0.84, P = 0.0103) were identified as independent prognostic factors for predicting better OS. Notably, a high ALI score was particularly indicative of longer survival in patients treated with the combination of etoposide and cisplatin. In conclusion, this study demonstrated that a high pretreatment ALI was significantly associated with better OS in patients with LS-SCLC undergoing definite CRT. This suggests that ALI could be a useful tool for predicting prognosis and guiding chemotherapy regimen selections in clinical practice for LS-SCLC.

Combinatorial approach of immuno-proton therapy in cancer: Rationale and potential impact

Cancer management is an expansive, growing, and evolving field. In the last decade or so, immunotherapy (IT) and particle beam therapy have made a tremendous impact in this domain. IT has already established itself as the fourth pillar of oncology. Recent emphasis has been centred around combination therapy, postulating additive or multiplicative effects of combining IT with one or more of the three conventional "pillars," that is, surgery, chemotherapy, and radiotherapy. Radio-IT is being increasingly explored and has shown promising outcomes in both preclinical and clinical settings. Particle beam therapy such as protons, when used as the radiotherapeutic modality in conjunction with IT, can potentially limit toxicities and improve this synergism further. Modern proton therapy has demonstrated a reduction in integral dose of radiation and radiation-induced lymphopenia in various sites. Protons, by virtue of their inherent clinically desirable physical and biological characteristics, namely, high linear energy transfer, relative biological effectiveness of range 1.1-1.6, and proven anti-metastatic and immunogenic potential in preclinical studies, might have a superior immunogenic profile than photons. Proton-IT combination is being studied currently by various groups in lung , head neck and brain tumors, and should be evaluated further in other subsites to replicate preclinical outcomes in a clinical setting. In this review, we summarize the currently available evidence for combinatorial approaches and feasibility of proton and IT combination, and thereafter highlight the emerging challenges for practical application of the same in clinics, while also proposing plausible solutions.

Anti-radiation effect of MRN-100: a hydro-ferrate fluid, in vivo

Ionizing radiation (IR) severely harms many organs, especially the hematopoietic tissue, mandating the development of protective nutraceuticals. MRN-100, a hydro-ferrate fluid, has been shown to protect γ-radiated fish against hematopoietic tissue damage and lethality. The current study aimed to examine MRN-100's protective effect against irradiated mice and explore the mechanisms underlying its effect. Mice received a single acute, sub-lethal, 5 Gy, whole body dose of X-ray IR. MRN-100 treatment was administered daily for 2-weeks pre-irradiation until 1-week post-irradiation. Spleen and blood were analysed for oxidative stress, hematological, histological and biochemical parameters. Radiation exposure markedly decreased complete blood count (CBC) parameters including hemoglobin, hematocrit, red blood cells, platelets, white blood cells and lymphocytes, and significantly increased neutrophils. In contrast, MRN-100 supplementation to irradiated mice ameliorated all CBC parameters and protected against DNA damage in both splenic cells and serum. It also had an antioxidant effect, increasing the levels of glutathione, superoxide dismutase, catalase and total antioxidant capacity, which were otherwise decreased by irradiation. MRN-100 intake reduced the oxidative stress biomarker levels of nitric oxide, protein carbonyl, malondialdehyde, reactive oxygen species and 8-hydroxydeoxyguanosine, a marker specific to DNA damage. Furthermore, MRN-100 enhanced serum iron and reversed the radiation-induced elevations of liver enzymes. Finally, MRN-100 protected splenic tissue from irradiation as observed by histology. We conclude that MRN-100 consumption may protect against oxidative stress generated by radiation exposure, suggesting that it may be employed as an adjuvant treatment to prevent radiation's severe damage to important organs.

Microcirculatory changes in the skin after postmastectomy radiotherapy in women with breast cancer

Postmastectomy radiotherapy (PMRT) increases the risk for complications after breast reconstruction. The pathophysiological mechanism underlying this increased risk is not completely understood. The aim of this study was to examine if there is a relationship between PMRT and microvascular perfusion in the skin directly after, and at 2 and 6 months after PMRT and to assess if there is impaired responsiveness to a topically applied vasodilator (Methyl nicotinate-MN) after PMRT. Skin microvascular responses after PMRT were measured on two sites in the irradiated chest wall of 22 women before, immediately after, and at 2 and 6 months after unilateral PMRT with the contralateral breast as a control. A significant increase in basal skin perfusion was observed in the irradiated chest wall immediately after RT (p < 0.0001). At 2 and 6 months after RT, there was no longer a difference in basal skin perfusion compared to the contralateral breast and compared to baseline. Similarly, the blood flow response in the skin after application of MN was stronger immediately after RT compared to before RT (p < 0.0001), but there was no difference at later time points. These results indicate that the increased risk for complications after surgical procedures are not directly related to changes in skin perfusion and microvascular responsiveness observed after postmastectomy RT.

Radiation-assisted strategies provide new perspectives to improve the nanoparticle delivery to tumor

Nanoparticles (NPs), with advantages in tumor targeting, have been extensively developed for anticancer treatment. However, the delivery efficacy of NPs tends to be heterogeneous in clinical research. Surprisingly, a traditional cancer treatment, radiotherapy (radiation), has been observed with the potential to improve the delivery of NPs by influencing the features of the tumor microenvironment, which provides new perspectives to overcome the barriers in the NPs delivery. Since the effect of radiation can also be enhanced by versatile NPs, these findings of radiation-assisted NPs delivery suggest innovative strategies combining radiotherapy with nanotherapeutics. This review summarizes the research on the delivery and therapeutic efficacy of NPs that are improved by radiation, focusing on relative mechanisms and existing challenges and opportunities.

Mesenchymal Stem Cells in Radiation-Induced Pulmonary Fibrosis: Future Prospects

Radiation-induced pulmonary fibrosis (RIPF) is a general and fatal side effect of radiotherapy, while the pathogenesis has not been entirely understood yet. By now, there is still no effective clinical intervention available for treatment of RIPF. Recent studies revealed mesenchymal stromal cells (MSCs) as a promising therapy treatment due to their homing and differentiation ability, paracrine effects, immunomodulatory effects, and MSCs-derived exosomes. Nevertheless, problems and challenges in applying MSCs still need to be taken seriously. Herein, we reviewed the mechanisms and challenges in the applications of MSCs in treating RIPF.

Role of vitamin D3 in tumor aggressiveness and radiation response for hepatocellular carcinoma

Locoregional control is a significant prognostic factor for hepatocellular carcinoma (HCC). Historically, the use of radiotherapy (RT) for HCC was limited owing to the low radiotolerance of the liver and the need for high RT doses for disease control. We aimed to examine if 1α,25-dihydroxyvitamin D3 (calcitriol) has a role in the tumor inhibition and the radiation response of HCC in vitro and in vivo, and explore the underlying mechanisms. The human and murine liver cancer cell lines were selected for cellular and animal experiments to investigate the changes in tumor characteristics and the radiation response after calcitriol supplementation. The effects induced by calcitriol supplementation on interleukin-6 (IL-6) signaling and the tumor immune microenvironment following RT were also examined. Our data revealed that calcitriol supplementation attenuated tumor aggressive behavior, decrease IL-6 expression, and augmented radiation-induced tumor inhibition. The biological changes following calcitriol treatment included suppressed epithelial-mesenchymal transition, attenuated cancer stem cell-like properties and increased radiation-induced reactive oxygen species and cell death in vitro. Regarding immune microenvironment, calcitriol attenuated the recruitment of myeloid-derived suppressor cell (MDSC) recruitment and increased the infiltration of cytotoxic T cells in tumor following RT. Furthermore, When the primary liver tumor was irradiated with larger dose per fraction, calcitriol induced a smaller size of synchronous unirradiated tumor in mice, which linked with attenuated IL-6 signaling and MDSC recruitment. In conclusion, calcitriol treatment reduced tumor aggressiveness and enhanced the radiation response. The inhibited IL-6 signaling and subsequently enhanced antitumor immunity might be responsible to augment radiation-induced tumoricidal effect induced by calcitriol. Based on our results, we suggest that calcitriol could exert the antitumor and radiosensitization effects for HCC, especially for multifocal tumors.

Tumor promoting roles of IL-10, TGF-β, IL-4, and IL-35: Its implications in cancer immunotherapy

Cytokines play a critical role in regulating host immune response toward cancer and determining the overall fate of tumorigenesis. The tumor microenvironment is dominated mainly by immune-suppressive cytokines that control effector antitumor immunity and promote survival and the proliferation of cancer cells, which ultimately leads to enhanced tumor growth. In addition to tumor cells, the heterogeneous immune cells present within the tumor milieu are the significant source of immune-suppressive cytokines. These cytokines are classified into a broad range; however, in most tumor types, the interleukin-10, transforming growth factor-β, interleukin-4, and interleukin-35 are consistently reported as immune-suppressive cytokines that help tumor growth and metastasis. The most emerging concern in cancer treatment is hijacking and restraining the activity of antitumor immune cells in the tumor niche due to a highly immune-suppressive environment. This review summarizes the role and precise functions of interleukin-10, transforming growth factor-β, interleukin-4, and interleukin-35 in modulating tumor immune contexture and its implication in developing effective immune-therapeutic approaches.

CONCISE CONCLUSION

Recent effort geared toward developing novel immune-therapeutic approaches faces significant challenges due to sustained mutations in tumor cells and a highly immune-suppressive microenvironment present within the tumor milieu. The cytokines play a crucial role in developing an immune-suppressive environment that ultimately dictates the fate of tumorigenesis. This review critically covers the novel aspects of predominant immune-suppressive cytokines such as interleukin-10, transforming growth factor-β, interleukin-4, and interleukin-35 in dictating the fate of tumorigenesis and how targeting these cytokines can help the development of better immune-therapeutic drug regimens for the treatment of cancer.

Symphony of nanomaterials and immunotherapy based on the cancer-immunity cycle

The immune system is involved in the initiation and progression of cancer. Research on cancer and immunity has contributed to the development of several clinically successful immunotherapies. These immunotherapies often act on a single step of the cancer–immunity cycle. In recent years, the discovery of new nanomaterials has dramatically expanded the functions and potential applications of nanomaterials. In addition to acting as drug-delivery platforms, some nanomaterials can induce the immunogenic cell death (ICD) of cancer cells or regulate the profile and strength of the immune response as immunomodulators. Based on their versatility, nanomaterials may serve as an integrated platform for multiple drugs or therapeutic strategies, simultaneously targeting several steps of the cancer–immunity cycle to enhance the outcome of anticancer immune response. To illustrate the critical roles of nanomaterials in cancer immunotherapies based on cancer–immunity cycle, this review will comprehensively describe the crosstalk between the immune system and cancer, and the current applications of nanomaterials, including drug carriers, ICD inducers, and immunomodulators. Moreover, this review will provide a detailed discussion of the knowledge regarding developing combinational cancer immunotherapies based on the cancer–immunity cycle, hoping to maximize the efficacy of these treatments assisted by nanomaterials.

Interest and Limits of [18F]ML-10 PET Imaging for Early Detection of Response to Conventional Chemotherapy

One of the current challenges in oncology is to develop imaging tools to early detect the response to conventional chemotherapy and adjust treatment strategies when necessary. Several studies evaluating PET imaging with 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) as a predictive tool of therapeutic response highlighted its insufficient specificity and sensitivity. The [¹⁸F]FDG uptake reflects only tumor metabolic activity and not treatment-induced cell death, which seems to be relevant for therapeutic evaluation. Therefore, to evaluate this parameter in vivo, several cell death radiotracers have been developed in the last years. However, few of them have reached the clinical trials. This systematic review focuses on the use of [¹⁸F]ML-10 (2-(5-[¹⁸F]fluoropentyl)-2-methylmalonic acid) as radiotracer of apoptosis and especially as a measure of tumor response to treatment. A comprehensive literature review concerning the preclinical and clinical investigations conducted with [¹⁸F]ML-10 was performed. The abilities and applications of this radiotracer as well as its clinical relevance and limitations were discussed. Most studies highlighted a good ability of the radiotracer to target apoptotic cells. However, the increase in apoptosis during treatment did not correlate with the radiotracer tumoral uptake, even using more advanced image analysis (voxel-based analysis). [¹⁸F]ML-10 PET imaging does not meet current clinical expectations for early detection of the therapeutic response to conventional chemotherapy. This review has pointed out the challenges of applying various apoptosis imaging strategies in clinical trials, the current methodologies available for image analysis and the future of molecular imaging to assess this therapeutic response.

Carbon ion radiotherapy boosts anti-tumour immune responses by inhibiting myeloid-derived suppressor cells in melanoma-bearing mice

Numerous studies have shown that carbon ion radiotherapy (CIRT) induces anti-cancer immune responses in melanoma patients, yet the mechanism remains elusive. The abundance of myeloid-derived suppressor cells (MDSC) in the tumour microenvironment is associated with therapeutic efficacy and disease outcome. This study analysed the changes in the immune contexture in response to the carbon ion treatment. The murine melanoma B16, MelanA, and S91 tumour models were established in syngeneic immunocompetent mice. Then, the tumours were irradiated with carbon ion beams, and flow cytometry was utilised to observe the immune contexture changes in the bone marrow, peripheral blood, spleen, and tumours. The immune infiltrates in the tumour tissues were further assessed using haematoxylin/eosin staining and immunohistochemistry. The immunoblot detected the expression of proteins associated with the JAK/STAT signalling pathway. The secretion of immune-related cytokines was examined using ELISA. Compared to conventional radiotherapy, particle beams have distinct advantages in cancer therapy. Here, the use of carbon ion beams (5 GyE) for melanoma-bearing mice was found to reduce the population of MDSC in the bone marrow, peripheral blood, and spleen of the animals via a JAK2/STAT3-dependent mechanism. The percentage of CD3⁺, CD4⁺, CD8⁺ T cells, macrophages, and natural killer cells increased after radiation, resulting in reduced tumour growth and prolonged overall survival in the three different mouse models of melanoma. This study, therefore, substantiated that CIRT boosts anti-tumour immune responses via the inhibition of MDSC.

MicroRNAs in prostate cancer following radiotherapy: Towards predicting response to radiation treatment

Prostate cancer (PCa) is the second most frequently diagnosed male cancer worldwide. Early diagnosis of PCa, response to therapy and prognosis still represent a challenge. Nearly 60% of PCa patients undergo radiation therapy (RT) which might cause side effects. In spite of numerous researches in this field, predictive biomarkers for radiation toxicity are still not elucidated. MicroRNAs as posttranscriptional regulators of gene expression are shown to be changed during and after irradiation. Manipulation with miRNA levels might be used to modulate response to RT-to reverse radioresistance-to induce radiosensitivity, or if needed, to reduce sensitivity to treatment to avoid side effects. In this review we have listed and described miRNAs involved in response to RT in PCa, and highlighted potential candidates for future biological tests predicting radiation response to RT, with the special focus on side effects of RT. Individual radiation response is a result of the interactions between physical characteristics of radiation treatment and biological background of each patient, and miRNA expression changes among others. According to described literature we concluded that let-7, miR-21, miR-34a, miR-146a, miR-155, and members of miR-17/92 cluster might be promising candidates for biological tests predicting radiosensitivity of PCa patients undergoing radiation treatment, and as future agents for modulation of radiation response. Predictive miRNA panels, especially for acute and late side effects of RT can serve as a starting point for decisions for individualized RT planning. We believe that this review might be one step closer to understanding molecular mechanisms underlying individual radiation response of patients with PCa.

Associations between initiating antihypertensive regimens on stage I-III colorectal cancer outcomes: A Medicare SEER cohort analysis

Purpose

Colorectal cancer (CRC) diagnosis is associated with high mortality in the United States and thus warrants the study of novel treatment approaches. Vascular changes are well observed in cancers and evidence indicates that antihypertensive (AH) medications may interfere with both tumor vasculature and in recruiting immune cells to the tumor microenvironment based on preclinical models. Extant literature also shows that AH medications are correlated with improved survival in some forms of cancer. Thus, this study sought to explore the impact of AH therapies on CRC outcomes.

Patients and Methods

This study was a non‐interventional, retrospective analysis of patients aged 65 years and older with CRC diagnosed from January 1, 2007 to December 31st, 2012 in the Surveillance, Epidemiology, and End‐Results (SEER)‐Medicare database. The association between AH drug utilization on AJCC stage I–III CRC mortality rates in patients who underwent treatment for cancer was examined using Cox proportional hazards models.

Results

The study cohort consisted of 13,982 patients diagnosed with CRC. Adjusted Cox proportional hazards regression showed that among these patients, the use of AH drug was associated with decreased cancer‐specific mortality (HR: 0.79, 95% CI: 0.75–0.83). Specifically, ACE inhibitors (hazard ratio [HR]: 0.84, 95% CI: 0.80–0.87), beta‐blockers (HR: 0.87, 95% CI: 0.84–0.91), and thiazide diuretics (HR: 0.83, 95% CI: 0.80–0.87) were found to be associated with decreased mortality. An association was also found between adherence to AH therapy and decreased cancer‐specific mortality (HR: 0.94, 95% CI: 0.90–0.98).

Conclusion

Further research needs to be performed, but AH medications may present a promising, low‐cost pathway to supporting CRC treatment for stage I–III cancers.

Correlation between the number of viable tumor cells and immune cells in the tumor microenvironment in non-small cell lung cancer after induction therapy

This study aims to determine the correlation between the percent viable tumor cells (%VTC) and the tumor microenvironment in resected non-small cell lung cancer after induction therapy. We enrolled 72 patients with non-small cell lung cancer (NSCLC) who received chemoradiotherapy (CRT) or chemotherapy (CT) prior to surgery. The ratio of the area of viable tumor cells to the total tumor area was calculated to obtain the %VTC. We also examined the number of CD4 (+), CD8 (+), CD20 (+) and FOXP3 (+) tumor-infiltrating lymphocytes (TILs), podoplanin (PDPN) (+) cancer-associated fibroblasts (CAFs), and CD204 (+) tumor-associated macrophages (TAMs) by immunohistochemistry (IHC). In the CRT group (n = 37), the tumors had significantly lower %VTC than the CT group (n = 35) (P < 0.001). In both of the CT group and CRT group, the %VTC showed a significant positive correlation with the number of CD204 (+)-TAMs (P = 0.014 and 0.005, respectively). Only in the CRT group, a higher number of CD204 (+) TAMs was associated with a shorter overall survival (OS) (P = 0.007) and recurrence-free survival (RFS) (P = 0.015). In the CRT group, the number of CD204 (+) TAMs is associated with %VTC and prognosis, suggesting that these cells may have tumor-promoting effects on the residual lung cancer in specific microenvironments after CRT.

Radiotherapy, Temozolomide, and Antiprogrammed Cell Death Protein 1 Treatments Modulate the Immune Microenvironment in Experimental High-Grade Glioma

BACKGROUND

The lack of immune synergy with conventional chemoradiation could explain the failure of checkpoint inhibitors in current clinical trials for high-grade gliomas (HGGs).

OBJECTIVE

To analyze the impact of radiotherapy (RT), Temozolomide (TMZ) and antiprogrammed cell death protein 1 (αPD1) (as single or combined treatments) on the immune microenvironment of experimental HGGs.

METHODS

Mice harboring neurosphere /CT-2A HGGs received RT (4 Gy, single dose), TMZ (50 mg/kg, 4 doses) and αPD1 (100 μg, 3 doses) as monotherapies or combinations. The influence on survival, tumor volume, and tumor-infiltrating immune cells was analyzed.

RESULTS

RT increased total T cells (P = .0159) and cluster of differentiation (CD)8+ T cells (P = .0078) compared to TMZ. Lymphocyte subpopulations resulting from TMZ or αPD1 treatment were comparable with those of controls. RT reduced M2 tumor-associated macrophages/microglia (P = .0019) and monocytic myeloid derived suppressor cells (mMDSCs, P = .0003) compared to controls. The effect on mMDSC was also seen following TMZ and αPD1 treatment, although less pronounced (P = .0439 and P = .0538, respectively). Combining RT with TMZ reduced CD8+ T cells (P = .0145) compared to RT alone. Adding αPD1 partially mitigated this effect as shown by the increased CD8+ T cells/Tregs ratio, even if this result failed to reach statistical significance (P = .0973). Changing the combination sequence of RT, TMZ, and αPD1 did not alter survival nor the immune effects.

CONCLUSION

RT, TMZ, and αPD1 modify the immune microenvironment of HGG. The combination of RT with TMZ induces a strong immune suppression which cannot be effectively counteracted by αPD1.

Scarred Lung. An Update on Radiation-Induced Pulmonary Fibrosis

Radiation-induced pulmonary fibrosis is a common severe long-time complication of radiation therapy for tumors of the thorax. Current therapeutic options used in the clinic include only supportive managements strategies, such as anti-inflammatory treatment using steroids, their efficacy, however, is far from being satisfactory. Recent studies have demonstrated that the development of lung fibrosis is a dynamic and complex process, involving the release of reactive oxygen species, activation of Toll-like receptors, recruitment of inflammatory cells, excessive production of nitric oxide and production of collagen by activated myofibroblasts. In this review we summarized the current state of knowledge on the pathophysiological processes leading to the development of lung fibrosis and we also discussed the possible treatment options.

Comparative Genomics Reveals Distinct Immune-oncologic Pathways in African American Men with Prostate Cancer

PURPOSE

The role of immune-oncologic mechanisms of racial disparities in prostate cancer remains understudied. Limited research exists to evaluate the molecular underpinnings of immune differences in African American men (AAM) and European American men (EAM) prostate tumor microenvironment (TME).

EXPERIMENTAL DESIGN

A total of 1,173 radiation-naïve radical prostatectomy samples with whole transcriptome data from the Decipher GRID registry were used. Transcriptomic expressions of 1,260 immune-specific genes were selected to assess immune-oncologic differences between AAM and EAM prostate tumors. Race-specific differential expression of genes was assessed using a rank test, and intergene correlational matrix and gene set enrichment was used for pathway analysis.

RESULTS

AAM prostate tumors have significant enrichment of major immune-oncologic pathways, including proinflammatory cytokines, IFNα, IFNγ, TNFα signaling, ILs, and epithelial-mesenchymal transition. AAM TME has higher total immune content score (ICS^HIGH) compared with 0 (37.8% vs. 21.9%, P = 0.003). AAM tumors also have lower DNA damage repair and are genomically radiosensitive as compared with EAM. IFITM3 (IFN-inducible transmembrane protein 3) was one of the major proinflammatory genes overexpressed in AAM that predicted increased risk of biochemical recurrence selectively for AAM in both discovery [HR_AAM = 2.30; 95% confidence interval (CI), 1.21-4.34; P = 0.01] and validation (HR_AAM = 2.42; 95% CI, 1.52-3.86; P = 0.0001) but not in EAM.

CONCLUSIONS

Prostate tumors of AAM manifest a unique immune repertoire and have significant enrichment of proinflammatory immune pathways that are associated with poorer outcomes. Observed immune-oncologic differences can aid in a genomically adaptive approach to treating prostate cancer in AAM.

Interactive Effects of PD-L1 Expression in Tumor and Immune Cells on Prognosis of Esophageal Squamous Cell Carcinoma: A One-Center Retrospective Cohort Study

PURPOSE

The present study aimed to investigate the prognostic effect of PD-L1 expressing in tumor and immune cells among patients with esophageal squamous cell carcinoma.

PATIENTS AND METHODS

We performed a retrospective cohort study by consecutively recruiting 142 patients. The clinicopathological features and PD-L1 expression on tumor and immune cells were independently evaluated by two pathologists.

RESULTS

The median expression rate of PD-L1 was 5% and 30% in tumor and immune cells, respectively. Patients with higher expression of PD-L1 in tumor cells had shorter disease-free and overall survival, and the HRs were 1.52 for relapse (95% CI: 0.88, 2.60) and 1.48 for death (95% CI: 0.82, 2.69). There was no significant association between the PD-L1 expression in immune cells and survival. However, among the patients with PD-L1 expression rate ≤30% in immune cells, the high expression rate of PD-L1 in tumor cells was significantly associated with the relapse and death, with HRs of 2.51 (95% CI: 1.25, 5.06) and 3.51 (95% CI: 1.57, 7.85), respectively. Among patients with PD-L1 expression rate >30% in immune cells, the PD-L1 expression in tumor cells did not show any association with the disease-free and overall survival.

CONCLUSION

Our study demonstrates that the integration of PD-L1 expression in tumor and immune cells could be used to predict the relapse and survival among patients with esophageal squamous cell carcinoma.

Harnessing the potential of multimodal radiotherapy in prostate cancer

Radiotherapy in combination with androgen deprivation therapy (ADT) is a standard treatment option for men with localized and locally advanced prostate cancer. However, emerging clinical evidence suggests that radiotherapy can be incorporated into multimodality therapy regimens beyond ADT, in combinations that include chemotherapy, radiosensitizing agents, immunotherapy and surgery for the treatment of men with localized and locally advanced prostate cancer, and those with oligometastatic disease, in whom the low metastatic burden in particular might be treatable with these combinations. This multimodal approach is increasingly recognized as offering considerable clinical benefit, such as increased antitumour effects and improved survival. Thus, radiotherapy is becoming a key component of multimodal therapy for many stages of prostate cancer, particularly oligometastatic disease.

Association of TIM-3 with BCLC Stage, Serum PD-L1 Detection, and Response to Transarterial Chemoembolization in Patients with Hepatocellular Carcinoma

Considering the increasing importance of immune checkpoints in tumor immunity we investigated the clinical relevance of serum T-cell immunoglobulin and mucin domain-3 (TIM-3) in patients with hepatocellular carcinoma (HCC). Serum TIM-3 levels were measured and their association with HCC stage and the detection of serum programmed death ligand-1 (PD-L1) were assessed. In patients submitted to transarterial chemoembolization (TACE), pre- and 1-week post-treatment TIM-3 levels were also evaluated. We studied 53 HCC patients with BCLC stages: 0 (5.7%), A (34%), B (32.1%), C (22.6%), and D (5.7%). The patients with advanced HCC (BCLC C) had significantly higher TIM-3 levels than patients with BCLC A (p = 0.009) and BCLC B (p = 0.019). TIM-3 levels were not associated with HCC etiology (p = 0.183). PD-L1 detection (9/53 patients) correlated with TIM-3 levels (univariate analysis, p = 0.047). In 33 patients who underwent TACE, post-treatment TIM-3 levels (231 pg/mL, 132-452) were significantly higher than pre-TACE levels (176 pg/mL, 110-379), (p = 0.036). Complete responders had higher post-TACE TIM-3 levels (534 pg/mL, 370-677) than partial responders (222 pg/mL, 131-368), (p = 0.028). Collectively, TIM-3 may have a role in anti-tumor immunity following TACE, setting a basis for combining immunotherapy and chemoembolization.

[18F]ML-10 PET imaging fails to assess early response to neoadjuvant chemotherapy in a preclinical model of triple negative breast cancer

PURPOSE

Pathological complete response to the neoadjuvant therapy (NAT) for triple negative breast cancer (TNBC) is predictive of prolonged patient survival. Methods for early evaluation of NAT efficiency are still needed, in order to rapidly adjust the therapeutic strategy in case of initial non-response. One option for this is molecular imaging of apoptosis induced by chemotherapy. Therefore, we investigated the capacity of [18F]ML-10 PET imaging, an apoptosis radiotracer, to detect tumor cell apoptosis and early predict the therapeutic response of human TNBC.

RESULTS

Initially, the induction of apoptosis by different therapies was quantified. We confirmed, in vitro, that paclitaxel or epirubicin, the fundamental cytotoxic drugs for breast cancer, induce apoptosis in TNBC cell lines. Exposure of TNBC models MDA-MB-231 and MDA-MB-468 to these drugs induced a significant increase (p < 0.01) of the apoptotic hallmarks: DNA fragmentation, membrane phospholipid scrambling, and PARP activation. Secondarily, apoptotic fraction was compared to the intracellular accumulation of the radiotracer. [18F]ML-10 accumulated in the apoptotic cells after 72 h of treatment by paclitaxel in vitro; this accumulation positively correlated with the apoptotic fraction. In vivo, [18F]ML-10 was rapidly cleared from the nontarget organs and mainly eliminated by the kidneys. Comparison of the in vivo [18F]FDG, [18F]FMISO, and [18F]ML-10 uptakes revealed that the tumor accumulation of [18F]ML-10 was directly related to the tumor hypoxia level. Finally, after the in vivo treatment of TNBC murine xenografts by paclitaxel, apoptosis was well induced, as demonstrated by the cleaved caspase-3 levels; however, no significant increase of [18F]ML-10 accumulation in the tumors was observed, either on day 3 or day 6 after the end of the treatment.

CONCLUSIONS

These results highlighted that PET imaging using [18F]ML-10 allows the visualization of apoptotic cells in TNBC models. Nevertheless, the increase of the chemotherapy-induced apoptotic response when using paclitaxel could not be assessed using this radiotracer in our mouse model.

Radiation-Induced Skin Fibrosis: Pathogenesis, Current Treatment Options, and Emerging Therapeutics

Radiotherapy (RT) has become an indispensable part of oncologic treatment protocols for a range of malignancies. However, a serious adverse effect of RT is radiodermatitis; almost 95% of patients develop moderate to severe skin reactions following radiation treatment. In the acute setting, these can be erythema, desquamation, ulceration, and pain. Chronically, soft tissue atrophy, alopecia, and stiffness can be noted. Radiodermatitis can delay oncologic treatment protocols and significantly impair quality of life. There is currently a paucity of effective treatment options and prevention strategies for radiodermatitis. Importantly, recent preclinical and clinical studies have suggested that fat grafting may be of therapeutic benefit, reversing detrimental changes to soft tissue following RT. This review outlines the damaging effects of RT on the skin and soft tissue as well as discusses available treatment options for radiodermatitis. Emerging strategies to mitigate detrimental, chronic radiation-induced changes are also presented.

Radiation therapy-induced reactive oxygen species specifically eliminates CD19+IgA+ B cells in nasopharyngeal carcinoma

Purpose

Nasopharyngeal carcinoma (NPC) is one of the most common head and neck cancers and is thought to be related to the mucosal immune system. Radiation therapy (RT) is the primary treatment for NPC due to the high radiosensitivity of cancer cells. However, little is known about the impact of RT on the mucosal immune system.

Patients and methods

In this study, the expression of immune markers CD19, CD24, CD27, CD8, and IgA before and after RT, were analyzed using flow cytometry. Cytokines were assessed using the enzyme-linked immunosorbent assay. Reactive oxygen species (ROS) was assayed by flow cytometry and fluorescence staining using 2ʹ,7ʹ -dichlorofluorescein diacetate.

Results

We found that primary NPC patients had a significant increase in CD19⁺CD138⁻IgA⁺ B cells, which was then decreased after RT. Interestingly, the changes in CD19⁺CD138⁻IgA⁺ B cell frequency was accompanied by corresponding frequency changes in cytotoxic T cells (CTL), which are powerful anti-tumor lymphocytes. Mechanistically, we found that ROS release during RT specifically eliminated CD19⁺CD138⁻IgA⁺ B cells.

Conclusion

These findings suggest that RT may regulate the immune system and opens up new avenues for the utilization of immune-radiotherapy in NPC.

Aloe vera modulates X-ray induced hematological and splenic tissue damage in mice

The present study was premeditated to examine the radioprotective effects of aqueous Aloe vera gel extract against whole-body X-ray irradiation-induced hematological alterations and splenic tissue injury in mice. Healthy male balb/c mice were divided into four groups: group 1, control; group 2, A. vera (50 mg/kg body weight) administered per oral on alternate days for 30 days (15 times); group 3, X-ray exposure of 2 Gy (0.25 Gy twice a day for four consecutive days in the last week of the experimental protocol); and group 4, A. vera + X-ray. X-ray exposure caused alterations in histoarchitecture of spleen along with enhanced clastogenic damage as assessed by micronucleus formation and apoptotic index. Irradiation caused an elevation in proinflammatory cytokines like tumor necrosis factor and interleukin-6, total leucocyte counts, neutrophil counts and decreased platelet counts along with unaltered red blood cell counts and hemoglobin. Irradiation also caused an elevation in reactive oxygen species (ROS), lipid peroxidation (LPO) levels, lactate dehydrogenase activity and alterations in enzymatic and nonenzymatic antioxidant defense mechanism in plasma and spleen. However, administration of A. vera gel extract ameliorated X-ray irradiation-induced elevation in ROS/LPO levels, histopathological and clastogenic damage. It also modulated biochemical indices, inflammatory markers, and hematological parameters. These results collectively indicated that the A. vera gel extract offers protection against whole-body X-ray exposure by virtue of its antioxidant, anti-inflammatory and anti-apoptotic potential.

Tumor Microenvironment as A "Game Changer" in Cancer Radiotherapy

Radiotherapy (RT), besides cancer cells, also affects the tumor microenvironment (TME): tumor blood vessels and cells of the immune system. It damages endothelial cells and causes radiation-induced inflammation. Damaged vessels inhibit the infiltration of CD8+ T lymphocytes into tumors, and immunosuppressive pathways are activated. They lead to the accumulation of radioresistant suppressor cells, including tumor-associated macrophages (TAMs) with the M2 phenotype, myeloid-derived suppressor cells (MDSCs), and regulatory T cells (Tregs). The area of tumor hypoxia increases. Hypoxia reduces oxygen-dependent DNA damage and weakens the anti-cancer RT effect. It activates the formation of new blood vessels and leads to cancer relapse after irradiation. Irradiation may also activate the immune response through immunogenic cell death induction. This leads to the "in situ" vaccination effect. In this article, we review how changes in the TME affect radiation-induced anticancer efficacy. There is a very delicate balance between the activation of the immune system and the immunosuppression induced by RT. The effects of RT doses on immune system reactions and also on tumor vascularization remain unclear. A better understanding of these interactions will contribute to the optimization of RT treatment, which may prevent the recurrence of cancer.

Targeting the Immunomodulatory CD73/Adenosine System to Improve the Therapeutic Gain of Radiotherapy

Extracellular adenosine is a potent endogenous immunosuppressive mediator critical to the maintenance of homeostasis in various normal tissues including the lung. Adenosine is either released from stressed or injured cells or generated from extracellular adenine nucleotides by the concerted action of the ectoenzymes ectoapyrase (CD39) and 5′ ectonucleotidase (CD73) that catabolize ATP to adenosine. An acute CD73-dependent increase of adenosine in normal tissues mostly exerts tissue protective functions whereas chronically increased adenosine-levels in tissues exposed to DNA damaging chemotherapy or radiotherapy promote pathologic remodeling processes and fibrosis for example in the skin and the lung. Importantly, cancer cells also express CD73 and high CD73 expression in the tumor tissue has been linked to poor overall survival and recurrence free survival in patients suffering from breast and ovarian cancer. CD73 and adenosine support growth-promoting neovascularization, metastasis, and survival in cancer cells. In addition, adenosine can promote tumor intrinsic or therapy-induced immune escape by various mechanisms that dampen the immune system. Consequently, modulating CD73 or cancer-derived adenosine in the tumor microenvironment emerges as an attractive novel therapeutic strategy to limit tumor progression, improve antitumor immune responses, avoid therapy-induced immune deviation, and potentially limit normal tissue toxicity. However, the role of CD73/adenosine signaling in the tumor and normal tissue responses to radiotherapy and its use as therapeutic target to improve the outcome of radiotherapy approaches is less understood. The present review will highlight the dual role of CD73 and adenosine in tumor and tissue responses to radiotherapy with a special focus to the lung. It will also discuss the potential benefits and risks of pharmacologic modulation of the CD73/adenosine system to increase the therapeutic gain of radiotherapy or combined radioimmunotherapy in cancer treatment.

PD-L1 Expression in Circulating Tumor Cells Increases during Radio(chemo)therapy and Indicates Poor Prognosis in Non-small Cell Lung Cancer

Preclinical studies demonstrated that radiation up-regulates PD-L1 expression in tumor cells, providing a rationale for combining PD-1/PD-L1 inhibitors with radiation. However this has not been validated in patients with non-small cell lung cancer due to the difficulty to obtain serial biopsies. Measuring PD-L1 expression in circulating tumor cells (CTCs), may allow real-time monitoring of immune activation in tumor. In this study, whole blood from non-metastatic NSCLC patients was collected before, during, and after radiation or chemoradiation using a microfluidic chip. PD-L1 expression in CTCs was assessed by immunofluorescence and qPCR and monitored through the course of treatment. Overall, PD-L1(+) CTCs were detected in 25 out of 38 samples (69.4%) with an average of 4.5 cells/ml. After initiation of radiation therapy, the proportion of PD-L1(+) CTCs increased significantly (median 0.7% vs. 24.7%, P < 0.01), indicating up-regulation of PD-L1 in tumor cells in response to radiation. In addition, patients positive for PD-L1 (≥5% of CTCs positive for PD-L1) at baseline had shorter PFS. Gene expression analysis revealed that higher levels of PD-L1 were associated with poor prognosis. Therefore, CTCs can be used to monitor dynamic changes of PD-L1 during radiation therapy which is potentially prognostic of response to treatment.

Rationale for combination of radiation therapy and immune checkpoint blockers to improve cancer treatment

Radiation therapy for cancer is considered to be immunosuppressive. However, the cellular response after radiation therapy may stimulate or suppress an immune response. The effect may vary with the tumor type and occasionally tumor regressions have been observed outside the irradiated volume, both in animal studies and in the clinic. A renewed interest in the role of immunity for the observed effect of radiation came with the current recognized role of immune checkpoint blockers (ICBs) for control of selected cancer types. We therefore here review preclinical studies and clinical reports on the interaction of ICBs and radiation as a basis for further clinical trials. Some tumor types where the combination of these modalities seems especially promising are also proposed.

The Response of Prostate Cancer to Androgen Deprivation and Irradiation Due to Immune Modulation

This study investigated changes in the immune system and the biological consequences of androgen deprivation therapy (ADT) and radiotherapy (RT) for augmenting the treatment response in prostate cancer, particularly for castration-resistant prostate cancer (CRPC). Human and murine prostate cancer cell lines were used to examine the response to ADT and RT in vitro and in vivo. Biological changes following treatment and related immune modulation in the tumor microenvironment were examined. Our results showed that CRPC cells were demonstrated to be more resistant to the RT and ADT treatments. ADT increased tumor inhibition following irradiation. The underlying changes included increased cell death, attenuated myeloid-derived suppressor cell recruitment, and an increase in the number of tumor-infiltrating T cells (TILs). Furthermore, when high-dose fractionated RT was given to the primary CRPC tumor, a smaller size of secondary non-irradiated tumor associated with increased TILs was noted in ADT-treated mice. In conclusion, treatment resistance in CRPC was associated with a more immunosuppressive microenvironment. Enhanced antitumor immunity was responsible for the augmented RT-induced tumoricidal effect induced by ADT. Immune modulation could be a promising strategy for prostate cancer, especially for metastatic CRPC.

Combining Radiotherapy and Immunotherapy in Lung Cancer: Can We Expect Limitations Due to Altered Normal Tissue Toxicity?

In recent decades, technical advances in surgery and radiotherapy, as well as breakthroughs in the knowledge on cancer biology, have helped to substantially improve the standard of cancer care with respect to overall response rates, progression-free survival, and the quality of life of cancer patients. In this context, immunotherapy is thought to have revolutionized the standard of care for cancer patients in the long term. For example, immunotherapy approaches such as immune checkpoint blockade are currently increasingly being used in cancer treatment, either alone or in combination with chemotherapy or radiotherapy, and there is hope from the first clinical trials that the appropriate integration of immunotherapy into standard care will raise the success rates of cancer therapy to a new level. Nevertheless, successful cancer therapy remains a major challenge, particularly in tumors with either pronounced resistance to chemotherapy and radiation treatment, a high risk of normal tissue complications, or both, as in lung cancer. Chemotherapy, radiotherapy and immunotherapy have the capacity to evoke adverse effects in normal tissues when administered alone. However, therapy concepts are usually highly complex, and it is still not clear if combining immunotherapy with radio(chemo)therapy will increase the risk of normal tissue complications, in particular since normal tissue toxicity induced by chemotherapy and radiotherapy can involve immunologic processes. Unfortunately, no reliable biomarkers are available so far that are suited to predict the unique normal tissue sensitivity of a given patient to a given treatment. Consequently, clinical trials combining radiotherapy and immunotherapy are attracting major attention, not only regarding efficacy, but also with regard to safety. In the present review, we summarize the current knowledge of radiation-induced and immunotherapy-induced effects in tumor and normal tissue of the lung, and discuss the potential limitations of combined radio-immunotherapy in lung cancer with a focus on the suspected risk for enhanced acute and chronic normal tissue toxicity.

Combined VLA-4-Targeted Radionuclide Therapy and Immunotherapy in a Mouse Model of Melanoma

Very late antigen-4 (VLA-4; also known as integrin α4β1) is expressed at high levels in aggressive and metastatic melanoma tumors and may provide an ideal target for imaging and targeted radionuclide therapy (TRT). 177Lu-DOTA-PEG4-LLP2A (177Lu-LLP2A) is a TRT that shows high affinity for VLA-4 and high uptake in B16F10 mouse melanoma tumors in vivo. Here, we report efficacy studies of 177Lu-LLP2A, alone and combined with immune checkpoint inhibitors (ICIs) (anti-PD-1, anti-PD-L1, and anti-CTLA-4 antibodies), in B16F10 tumor-bearing mice. Methods: Tumor cells (1 × 106) were implanted subcutaneously in C57BL/6 mice. After 8-10 d, the mice were randomized into 8 groups. 177Lu-LLP2A was injected intravenously on day 8 or 9 (single dose), and ICI antibodies were administered intraperitoneally in 3 doses. Tumor growth was monitored over time via calipers. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining for apoptosis was performed on fixed tumors. In a separate study, Cy3-LLP2A or Cy3-scrambled LLP2A was injected in tumor-bearing mice, and tumors were collected 4 h after injection and then analyzed by flow cytometry and immunofluorescence microscopy using different immune cell markers. Results: TRT alone showed efficacy comparable to the dual-ICI anti-PD-1 + anti-CTLA-4 or anti-PD-L1 + anti-CTLA-4, whereas TRT + ICIs significantly enhanced survival. TUNEL staining showed that the highest levels of apoptosis were in the TRT + ICI groups. In addition to targeting tumor cells, TRT also bound immune cells in the tumor microenvironment. Flow cytometry data showed that the tumors consisted of about 77% tumor cells and fibroblasts (CD45-negative/CD49d-positive) and about 23% immune cells (CD45-positive/CD49d-positive) and that immune cells expressed higher levels of VLA-4. Cy3-LLP2A and CD49d colocalized with macrophages (CD68), T cells (CD8, CD4), and B cells (CD19). Immunohistochemical analysis identified a significant colocalization of Cy3-LLP2A and CD68. Conclusion: Combination treatment with TRT + ICIs targets both tumor cells and immune cells and has potential as a therapeutic agent in patients with metastatic melanoma.

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.

Inhibiting the CD8+ T cell infiltration in the tumor microenvironment after radiotherapy is an important mechanism of radioresistance

Endogenous immune response participates in tumor control, and radiotherapy has immune modulatory capacity, but the role of immune modulation in the tumor microenvironment invoked by radiotherapy in radiosensitivity is poorly defined. In the present study, a radio-resistant melanoma cell line was obtained after repeated irradiation to the parental tumor in C57BL/6 mice. Radiotherapy resulted in aggregation of CD8⁺ and CD3⁺ T cells, and decrease of myeloid-derived suppressor cells and dendritic cells in the parental tumor, but not in the resistant tumors. CD4⁺ T cells and B cells did not change significantly. The CD8⁺ T cell infiltration after radiotherapy is important for tumor response, because in the nude mice and CD8⁺ T cell-depleted C57BL/6 mice, the parental and resistant tumor has similar radiosensitivity. Patients with good radiation response had more CD8⁺ T cells aggregation after radiotherapy. Radiotherapy resulted in robust transcription of T cell chemoattractant in the parental cells, and the expression of CCL5 was much higher. These results reveal a novel mechanism of radioresistance, tumor cells inhibit the infiltration of CD8⁺ T cell after radiotherapy and become radioresistant. Increasing CD8⁺ T cell infiltration after RT may be an effective way to improve tumor radiosensitivity.

Chemoradiation-Induced Alteration of Programmed Death-Ligand 1 and CD8+ Tumor-Infiltrating Lymphocytes Identified Patients With Poor Prognosis in Rectal Cancer: A Matched Comparison Analysis

PURPOSE

To evaluate chemoradiotherapy (CRT)-induced changes in the expression levels of programmed death-ligand 1 (PD-L1) and CD8⁺ tumor-infiltrating lymphocytes (TILs) and prognostic associations in rectal cancer.

METHODS AND MATERIALS

We performed a paired analysis using pre-CRT biopsies and the corresponding post-CRT resected tissues of 123 rectal cancer patients undergoing preoperative CRT followed by surgery between 2005 and 2012. Immunohistochemistry of PD-L1 and CD8 was analyzed for the specimens.

RESULTS

The expression levels of PD-L1 and density of CD8⁺ TILs increased after CRT (P<.001 for both). With cutoffs using each median value, sustained higher expression of PD-L1 at pre- and post-CRT (high-to-high) was associated with less increase in the density of CD8⁺ TILs (P=.020). Patients representing sustained high-to-high PD-L1 expression had poorer overall survival and disease-free interval on univariate Kaplan-Meier analysis (P=.018 and .029, respectively), with inferior disease-free interval in low-to-low density CD8⁺ TILs (P=.010). On multivariate analysis, 2 subgroups with high baseline PD-L1 expression level, the high-to-low and high-to-high alterations, showed worse overall survival (hazard ratio 8.34, 95% confidence interval 1.85-37.53 and hazard ratio 11.03, 95% confidence interval 2.33-52.29, respectively), with the highest mortality risk observed in the high-to-high group.

CONCLUSIONS

This study verified the CRT-induced immunologic shift toward increases in PD-L1 expression and density of CD8⁺ TILs in rectal cancer patients. The alteration profiles of checkpoint-related molecules identified the patients with poor prognosis, suggesting potential candidates who can benefit from combining CRT and checkpoint inhibitors.

γ-irradiation from radiotherapy improves the virulence potential of Candida tropicalis

AIM

To evaluate if radiation used in radiotherapy can cause changes in the virulence potential of Candida tropicalis ATCC 750.

MATERIALS & METHODS

C. tropicalis was exposed in vitro to identical dose and scheme of irradiation would be used in patients with head and neck cancer. Some virulence parameters were analyzed before and after irradiation.

RESULTS

Colony morphologies were irreversibly affected by irradiation. Increase in growth rate, filamentation, adhesion on cell lines and phagocytosis process were also observed. Overall the irradiated C. tropicalis cells became more efficient at causing systemic infection in mice.

CONCLUSION

γ-radiation induced important changes in C. tropicalis increasing its virulence profile, which could directly affect the relationship between yeasts and hosts.

In Situ Vaccination after Accelerated Hypofractionated Radiation and Surgery in a Mesothelioma Mouse Model

Purpose: How best to sequence and integrate immunotherapy into standard of care is currently unknown. Clinical protocols with accelerated nonablative hypofractionated radiation followed by surgery could provide an opportunity to implement immune checkpoint blockade.Experimental Design: We therefore assessed the impact of nonablative hypofractionated radiation on the immune system in combination with surgery in a mouse mesothelioma model. Blunt surgery (R1 resection) was used to analyze the short-term effect, and radical surgery (R0 resection) was used to analyze the long-term effect of this radiation protocol before surgery.Results: Nonablative hypofractionated radiation led to a specific immune activation against the tumor associated with significant upregulation of CD8⁺ T cells, limiting the negative effect of an incomplete resection. The same radiation protocol performed 7 days before radical surgery led to a long-term antitumor immune protection that was primarily driven by CD4⁺ T cells. Radical surgery alone or with a short course of nonablative radiation completed 24 hours before radical surgery did not provide this vaccination effect. Combining this radiation protocol with CTLA-4 blockade provided better results than radiation alone. The effect of PD-1 or PD-L1 blockade with this radiation protocol was less effective than the combination with CTLA-4 blockade.Conclusions: A specific activation of the immune system against the tumor contributes to the benefit of accelerated, hypofractionated radiation before surgery. Nonablative hypofractionated radiation combined with surgery provides an opportunity to introduce immune checkpoint blockades in the clinical setting. Clin Cancer Res; 23(18); 5502-13. ©2017 AACR.

Potential immunotherapy targets in recurrent cervical cancer

OBJECTIVE

Our objective was to characterize the intra and peritumoral immune profile in recurrent cervical cancers to identify rational immunotherapy targets.

METHODS

Archival pelvic exenteration specimens were examined using a validated multiplex immuno-fluorescent panel of antibodies against cluster of differentiation 8 (CD8), cluster of differentiation 68 (CD68), forkhead box P3 (FoxP3), programmed cell death protein 1 (PD1), and programmed death-ligand 1 (PD-L1, N=28). Clinical data were abstracted from the electronic medical record.

RESULTS

Cytotoxic T cells, macrophages, and regulatory T cells were found in higher densities in peritumoral stroma (CD8+ density 497.7 vs 83.5, p<0.0001, CD68+ density 345.0 vs 196.7, p=0.04, FoxP3+ density 214.5 vs 35.6, p<0.0001). Antigen experienced T cells (PD1+) were higher in peritumoral compared to tumor tissue (median normalized fluorescence intensity 0.05 vs 0.0085, p<0.001). Although there was a higher median density of intratumoral cytotoxic T cells and macrophages compared to regulatory T cells (median density CD8+ 83.5 vs 35.6, p<0.05, median density 196.7 vs 35.6, p<0.05), the presence of macrophages correlated with the presence of regulatory T cells in tumors (r=0.58, p=0.001).

CONCLUSIONS

While cytotoxic T cells are present in tumor tissue to varying degrees, their density is lower than in peritumoral stroma, suggesting intratumoral exclusion or destruction of T cells. Higher densities of intratumoral macrophages compared to regulatory T cells suggest macrophages may be important contributors to the immunosuppressive tumor environment. Future directions for combination therapy include altering T cell trafficking and targeting tumor associated macrophages (TAMs) to enhance intratumoral activated T cell density and effect a more robust immune response.

Tumor hypoxia and reoxygenation: the yin and yang for radiotherapy

Tumor hypoxia, a common feature occurring in nearly all human solid tumors is a major contributing factor for failures of anticancer therapies. Because ionizing radiation depends heavily on the presence of molecular oxygen to produce cytotoxic effect, the negative impact of tumor hypoxia had long been recognized. In this review, we will highlight some of the past attempts to overcome tumor hypoxia including hypoxic radiosensitizers and hypoxia-selective cytotoxin. Although they were (still are) a very clever idea, they lacked clinical efficacy largely because of ‘reoxygenation’ phenomenon occurring in the conventional low dose hyperfractionation radiotherapy prevented proper activation of these compounds. Recent meta-analysis and imaging studies do however indicate that there may be a significant clinical benefit in lowering the locoregional failures by using these compounds. Latest technological advancement in radiotherapy has allowed to deliver high doses of radiation conformally to the tumor volume. Although this technology has brought superb clinical responses for many types of cancer, recent modeling studies have predicted that tumor hypoxia is even more serious because ‘reoxygenation’ is low thereby leaving a large portion of hypoxic tumor cells behind. Wouldn’t it be then reasonable to combine hypoxic radiosensitizers and/or hypoxia-selective cytotoxin with the latest radiotherapy? We will provide some preclinical and clinical evidence to support this idea hoping to revamp an enthusiasm for hypoxic radiosensitizers or hypoxia-selective cytotoxins as an adjunct therapy for radiotherapy.