Radio-Immunotherapy-Induced Immunogenic Cancer Cells as Basis for Induction of Systemic Anti-Tumor Immune Responses - Pre-Clinical Evidence and Ongoing Clinical Applications

High-dose radiation-induced immunogenic cell death of bladder cancer cells leads to dendritic cell activation

Radiotherapy is a commonly used method in the treatment of bladder cancers (BC). Radiation-induced immunogenic cell death (ICD) is related to the immune response against cancers and their prognoses. Even though dendritic cells (DC) act as powerful antigen-presenting cells in the body, their precise role in this ICD process remains unclear. Accordingly, an in vitro study was undertaken to ascertain whether high-dose radiation-induced ICD of BC cells could regulate the immune response of DC. The results indicated that high-dose radiation treatments of BC cells significantly increased their levels of apoptosis, blocked their cell cycle in the G2/M phase, increased their expression of ICD-related proteins, and upregulated their secretion of CCL5 and CCL21 which control the directed migration of DC. It was also noted that expression of CD80, CD86, CCR5, and CCR7 on DC was upregulated in the medium containing the irradiated cells. In conclusion, the present findings illustrate that high-dose radiation can induce the occurrence of ICD within BC cells, concomitantly resulting in the activation of DC. Such findings could be of great significance in increasing the understanding how radiotherapy of BC may work to bring about reductions in cell activity and how these processes in turn lead to immunoregulation of the function of DC.

A comprehensive overview of radiation therapy impacts of various cancer treatments and pivotal role in the immune system

The cancer treatment landscape is significantly evolving, focusing on advanced radiation therapy methods to maximize effectiveness and minimize the adverse effects. Recognized as a pivotal component in cancer and disease treatment, radiation therapy (RT) has drawn attention in recent research that delves into its intricate interplay with inflammation and the immune response. This exploration unveils the underlying processes that significantly influence treatment outcomes. In this context, the potential advantages of combining bronchoscopy with RT across diverse clinical scenarios, alongside the targeted impact of brachytherapy, are explored. Concurrently, radiation treatments serve multifaceted roles such as DNA repair, cell elimination, and generating immune stress signaling molecules known as damage-associated molecular patterns, elucidating their effectiveness in treating various diseases. External beam RT introduces versatility by utilizing particles such as photons, electrons, protons, or carbon ions, each offering distinct advantages. Advanced RT techniques contribute to the evolving landscape, with emerging technologies like FLASH, spatially fractionated RT, and others poised to revolutionize the field. The comprehension of RT, striving for improved treatment outcomes, reduced side effects, and facilitating personalized and innovative treatments for cancer and noncancer patients. After navigating these advancements, the goal is fixed to usher in a new era in which RT is a cornerstone of precision and effectiveness in medical interventions. In summarizing the myriad findings, the review underscores the significance of understanding the differential impacts of radiation approaches on inflammation and immune modulation, offering valuable insights for developing innovative therapeutic interventions that harness the immune system in conjunction with RT.

Solid tumours showing oligoprogression to immune checkpoint inhibitors have the potential for abscopal effects

PURPOSE

Given the uncertainty surrounding the abscopal effect (AE), it is imperative to identify promising treatment targets. In this study, we aimed to explore the incidence of AE when administering radiotherapy to patients with oligoprogressive solid tumours while they are undergoing treatment with immune checkpoint inhibitors (ICIs).

MATERIALS AND METHODS

In this multicentre prospective observational study, oligoprogressive disease was defined as a < 20% increase in lesions compared to > 2 months before enrolment. We enrolled patients who requested radiotherapy during the ICI rest period between 2020 and 2023. AE was considered present if ≥ 1 non-irradiated lesion decreased by ≥ 30% before the next line of systemic therapy started.

RESULTS

Twelve patients were included in this study; the common primary lesions were in the lungs (four patients) and kidneys (three patients). AEs were observed in six (50%) patients, with a median time to onset of 4 (range 2-9) months after radiotherapy. No significant predictors of AEs were identified. Patients in the AE group had a significantly better 1-year progression-free survival (PFS) rate than those in the non-AE group (p = 0.008). Two patients from the AE group were untreated and progression-free at the last follow-up. Four (33%) patients experienced grade 2 toxicity, with two cases attributed to radiotherapy and the other two to ICI treatment. No grade 3 or higher toxicities were observed in any category.

CONCLUSION

Patients with oligoprogressive disease may be promising targets with potential for AEs. AEs can lead to improved PFS and, in rare cases, to a certain progression-free period without treatment. Irradiating solid tumours in patients with oligoprogressive disease during immune checkpoint inhibitor therapy may be a promising target with the potential for abscopal effects (AEs). AEs can lead to improved progression-free survival and, in rare cases, to a certain progression-free period without treatment.

Combine radiotherapy and immunotherapy in esophageal squamous cell carcinoma

Immune checkpoint inhibitors(ICIs) have improved the survival of advanced esophageal squamous cell carcinoma (ESCC) patients. Radiotherapy is one of the common therapies to treat esophageal cancer. However, whether combination radiation therapy can increase the efficacy of immunotherapy is still up for debate. Radiotherapy combined with immunotherapy has proven to be a reliable and effective treatment for tumors, and it can work in combination with immunotherapy to achieve better anti-tumor effects. This review aims to discuss the efficacy and safety of combining radiotherapy and immunotherapy to treat ESCC by stages as well as the optimum radiotherapy dose and target volume, with a summary of clinical trials in ESCC.

Potential of damage associated molecular patterns in synergising radiation and the immune response in oesophageal cancer

BACKGROUND

There is an intimate crosstalk between cancer formation, dissemination, treatment response and the host immune system, with inducing tumour cell death the ultimate therapeutic goal for most anti-cancer treatments. However, inducing a purposeful synergistic response between conventional therapies and the immune system remains evasive. The release of damage associated molecular patterns (DAMPs) is indicative of immunogenic cell death and propagation of established immune responses. However, there is a gap in the literature regarding the importance of DAMP expression in oesophageal adenocarcinoma (OAC) or by immune cells themselves.

AIM

To investigate the effects of conventional therapies on DAMP expression and to determine whether OAC is an immunogenic cancer.

METHODS

We investigated the levels of immunogenic cell death-associated DAMPs, calreticulin (CRT) and HMGB1 using an OAC isogenic model of radioresistance. DAMP expression was also assessed directly using ex vivo cancer patient T cells (n = 10) and within tumour biopsies (n = 9) both pre and post-treatment with clinically relevant chemo(radio)therapeutics.

RESULTS

Hypoxia in combination with nutrient deprivation significantly reduces DAMP expression by OAC cells in vitro. Significantly increased frequencies of T cell DAMP expression in OAC patients were observed following chemo(radio)therapy, which was significantly higher in tumour tissue compared with peripheral blood. Patients with high expression of HMGB1 had a significantly better tumour regression grade (TRG 1-2) compared to low expressors.

CONCLUSION

In conclusion, OAC expresses an immunogenic phenotype with two distinct subgroups of high and low DAMP expressors, which correlated with tumour regression grade and lymphatic invasion. It also identifies DAMPs namely CRT and HMGB1 as potential promising biomarkers in predicting good pathological responses to conventional chemo(radio)therapies currently used in the multimodal management of locally advanced disease.

Smart Radiotherapy Biomaterials for Image-Guided In Situ Cancer Vaccination

Recent studies have highlighted the potential of smart radiotherapy biomaterials (SRBs) for combining radiotherapy and immunotherapy. These SRBs include smart fiducial markers and smart nanoparticles made with high atomic number materials that can provide requisite image contrast during radiotherapy, increase tumor immunogenicity, and provide sustained local delivery of immunotherapy. Here, we review the state-of-the-art in this area of research, the challenges and opportunities, with a focus on in situ vaccination to expand the role of radiotherapy in the treatment of both local and metastatic disease. A roadmap for clinical translation is outlined with a focus on specific cancers where such an approach is readily translatable or will have the highest impact. The potential of FLASH radiotherapy to synergize with SRBs is discussed including prospects for using SRBs in place of currently used inert radiotherapy biomaterials such as fiducial markers, or spacers. While the bulk of this review focuses on the last decade, in some cases, relevant foundational work extends as far back as the last two and half decades.

Immune microenvironment: novel perspectives on bone regeneration disorder in osteoradionecrosis of the jaws

Osteoradionecrosis of the jaws (ORNJ) is a severe complication that occurs after radiotherapy of head and neck malignancies. Clinically, conservative treatments and surgeries for ORNJ exhibited certain therapeutic effects, whereas the regenerative disorder of the post-radiation jaw remains a pending problem to be solved. In recent years, the recognition of the role of the immune microenvironment has led to a shift from an osteoblasts (OBs) or bone marrow mesenchymal stromal cells (BMSCs)-centered view of bone regeneration to the concept of a complicated microecosystem that supports bone regeneration. Current advances in osteoimmunology have uncovered novel targets within the immune microenvironment to help improve various regeneration therapies, notably therapies potentiating the interaction between BMSCs and immune cells. However, these researches lack a thorough understanding of the immune microenvironment and the interaction network of immune cells in the course of bone regeneration, especially for the post-operative defect of ORNJ. This review summarized the composition of the immune microenvironment during bone regeneration, how the immune microenvironment interacts with the skeletal system, and discussed existing and potential strategies aimed at targeting cellular and molecular immune microenvironment components.

Radiation-induced PD-L1 expression in tumor and its microenvironment facilitates cancer-immune escape: a narrative review

Background and Objective

Radiotherapy (RT) is one of the fundamental anti-cancer regimens by means of inducing in situ tumor vaccination and driving a systemic anti-tumor immune response. It can affect the tumor microenvironment (TME) components consisting of blood vessels, immunocytes, fibroblasts, and extracellular matrix (ECM), and might subsequently suppress anti-tumor immunity through expression of molecules such as programmed death ligand-1 (PD-L1). Immune checkpoint inhibitors (ICIs), especially anti-programmed cell death 1 (PD-1)/PD-L1 therapies, have been regarded as effective in the reinvigoration of the immune system and another major cancer treatment. Experimentally, combination of RT and ICIs therapy shows a greater synergistic effect than either therapy alone.

Methods

We performed a narrative review of the literature in the PubMed database. The research string comprised various combinations of "radiotherapy", "programmed death-ligand 1", "microenvironment", "exosome", "myeloid cell", "tumor cell", "tumor immunity". The database was searched independently by two authors. A third reviewer mediated any discordance of the results of the two screeners.

Key Content and Findings

RT upregulates PD-L1 expression in tumor cells, tumor-derived exosomes (TEXs), myeloid-derived suppressor cells (MDSCs), and macrophages. The signaling pathways correlated to PD-L1 expression in tumor cells include the DNA damage signaling pathway, epidermal growth factor receptor (EGFR) pathway, interferon gamma (IFN-γ) pathway, cGAS-STING pathway, and JAK/STATs pathway.

Conclusions

PD-L1 upregulation post-RT is found not only in tumor cells but also in the TME and is one of the mechanisms of tumor evasion. Therefore, further studies are necessary to fully comprehend this biological process. Meanwhile, combination of therapies has been shown to be effective, and novel approaches are to be developed as adjuvant to RT and ICIs therapy.

Radiotherapy-Related Gene Signature in Prostate Cancer

Simple Summary

Radiation therapy (RT) is an established therapeutic regimen for prostate cancer patients which aims for the direct elimination of tumor cells in the prostate gland and occasionally at distant anatomic sites. In this study, we performed next-generation sequencing-based gene expression analysis in peripheral blood from prostate cancer patients obtained pre- and post-radiotherapy and found six independently down-regulated genes including CCR7, FCGR2B, BTLA, CD6, CD3D, and CD3E. The analysis of the expression of the 6-genes as a signature also revealed significantly lower levels post- vs. pre-radiotherapy. Data extracted from the PRAD (PRostate ADenocarcinomas) dataset linked low levels of the 6-gene signature to better survival. More importantly, this 6-gene signature strongly correlated with a favorable prognosis regardless of poor standard clinicopathological parameters (i.e., Gleason score ≥ 8 and T3), thus highlighting its potential predictive value.

Abstract

Radiotherapy for localized prostate cancer has increased the cure and survival rates of patients. Besides its local tumoricidal effects, ionizing radiation has been linked to mechanisms leading to systemic immune activation, a phenomenon called the abscopal effect. In this study, we performed gene expression analysis on peripheral blood from prostate cancer patients obtained post- radiotherapy and showed that 6 genes, including CCR7, FCGR2B, BTLA, CD6, CD3D, and CD3E, were down-regulated by a range of 1.5–2.5-fold as compared to pre-radiotherapy samples. The expression of the signature consisting of these six genes was also significantly lower post- vs. pre-radiotherapy. These genes are involved in various tumor-promoting immune pathways and their down-regulation post-radiotherapy could be considered beneficial for patients. This is supported by the fact that low mRNA expression levels for the 6-gene signature in the prostate tumor tissue was linked to better survival. Importantly, we report that this 6-gene signature strongly correlated with a favorable prognosis regardless of poor standard clinicopathological parameters (i.e., Gleason score ≥ 8 and T3 (including T3a and T3b). Our pioneering data open the possibility that the 6-gene signature identified herein may have a predictive value, but this requires further long-term studies.

Forcing the Antitumor Effects of HSPs Using a Modulated Electric Field

The role of Heat Shock Proteins (HSPs) is a “double-edged sword” with regards to tumors. The location and interactions of HSPs determine their pro- or antitumor activity. The present review includes an overview of the relevant functions of HSPs, which could improve their antitumor activity. Promoting the antitumor processes could assist in the local and systemic management of cancer. We explore the possibility of achieving this by manipulating the electromagnetic interactions within the tumor microenvironment. An appropriate electric field may select and affect the cancer cells using the electric heterogeneity of the tumor tissue. This review describes the method proposed to effect such changes: amplitude-modulated radiofrequency (amRF) applied with a 13.56 MHz carrier frequency. We summarize the preclinical investigations of the amRF on the HSPs in malignant cells. The preclinical studies show the promotion of the expression of HSP70 on the plasma membrane, participating in the immunogenic cell death (ICD) pathway. The sequence of guided molecular changes triggers innate and adaptive immune reactions. The amRF promotes the secretion of HSP70 also in the extracellular matrix. The extracellular HSP70 accompanied by free HMGB1 and membrane-expressed calreticulin (CRT) form damage-associated molecular patterns encouraging the dendritic cells’ maturing for antigen presentation. The process promotes killer T-cells. Clinical results demonstrate the potential of this immune process to trigger a systemic effect. We conclude that the properly applied amRF promotes antitumor HSP activity, and in situ, it could support the tumor-specific immune effects produced locally but acting systemically for disseminated cells and metastatic lesions.

T-Cell Repertoire in Tumor Radiation: The Emerging Frontier as a Radiotherapy Biomarker

Simple Summary

Radiotherapy constitutes an essential component of the treatment for malignant disease. Besides its direct effect on cancer cells, namely, DNA damage and cell death, ionizing irradiation also mediates indirect antitumor effects that are mostly mediated by the immune system. Investigations into the processes underlying the interaction between radiotherapy and the immune system have uncovered mechanisms that can be exploited to promote the antitumor efficacy of radiotherapy both locally in the irradiated primary tumor and also at distant lesions in non-irradiated tumors. Because of its capacity to stimulate antitumor immunity, radiotherapy is also applied in combination with immune-checkpoint-inhibition-based immunotherapy. This review discusses the important pathways that govern the synergistic interactions between ionizing radiation and antitumor immune reactivity. Unravelling these involved mechanisms is mandatory for the successful application of anticancer radiotherapy and immunotherapy. We also place emphasis on the need for biomarkers that will aid in the selection of patients most likely to benefit from such combined treatments.

Abstract

Radiotherapy (RT) is a therapeutic modality that aims to eliminate malignant cells through the induction of DNA damage in the irradiated tumor site. In addition to its cytotoxic properties, RT also induces mechanisms that result in the promotion of antitumor immunity both locally within the irradiation field but also at distant tumor lesions, a phenomenon that is known as the “abscopal” effect. Because the immune system is capable of sensing the effects of RT, several treatment protocols have been assessing the synergistic role of radiotherapy combined with immunotherapy, collectively referred to as radioimmunotherapy. Herein, we discuss mechanistic insights underlying RT-based immunomodulation, which also enhance our understanding of how RT regulates antitumor T-cell-mediated immunity. Such knowledge is essential for the discovery of predictive biomarkers and for the improvement of clinical trials investigating the efficacy of radio-immunotherapeutic modalities in cancer patients.

The microbiome and precision oncology: an emerging paradigm in anticancer therapy

Understanding the host-microbiome interactions has emerged as an essential factor in improving human health and disease. Recent advances in understanding the intimate relationship of microbes with the host have uncovered various previously unknown underlying causes of disease development, progression, and treatment failure. The dynamic behaviour of the microbiome confers the heterogeneity in treatment response by modulating the immune response and inflammation in various diseases, including cancer. The growing insights into the microbial modulation of cancer through immunoregulation, xenometabolism, and increase in toxicity open a new era of personalised medicine. In the current review, we discuss the essential roles played by the microbiome in modulating the efficacy and toxicity of anticancer therapies (immunotherapy, chemotherapy, and radiotherapy). We also outline the current state of personalised medicine in the context of cancer and microbiome modulation. The knowledge about the role of cancer-microbiome communication will lead to designing other precise microbial modulation strategies for cancer treatment through enhanced efficacy and decreased toxicity.

Heterogeneous Heat Absorption Is Complementary to Radiotherapy

Simple Summary

This review shows the advantages of heterogeneous heating of selected malignant cells in harmonic synergy with radiotherapy. The main clinical achievement of this complementary therapy is its extreme safety and minimal adverse effects. Combining the two methods opens a bright perspective, transforming the local radiotherapy to the antitumoral impact on the whole body, destroying the distant metastases by “teaching” the immune system about the overall danger of malignancy.

Abstract

(1) Background: Hyperthermia in oncology conventionally seeks the homogeneous heating of the tumor mass. The expected isothermal condition is the basis of the dose calculation in clinical practice. My objective is to study and apply a heterogenic temperature pattern during the heating process and show how it supports radiotherapy. (2) Methods: The targeted tissue’s natural electric and thermal heterogeneity is used for the selective heating of the cancer cells. The amplitude-modulated radiofrequency current focuses the energy absorption on the membrane rafts of the malignant cells. The energy partly “nonthermally” excites and partly heats the absorbing protein complexes. (3) Results: The excitation of the transmembrane proteins induces an extrinsic caspase-dependent apoptotic pathway, while the heat stress promotes the intrinsic caspase-dependent and independent apoptotic signals generated by mitochondria. The molecular changes synergize the method with radiotherapy and promote the abscopal effect. The mild average temperature (39–41 °C) intensifies the blood flow for promoting oxygenation in combination with radiotherapy. The preclinical experiences verify, and the clinical studies validate the method. (4) Conclusions: The heterogenic, molecular targeting has similarities with DNA strand-breaking in radiotherapy. The controlled energy absorption allows using a similar energy dose to radiotherapy (J/kg). The two therapies are synergistically combined.

Vascular Microenvironment, Tumor Immunity and Immunotherapy

Immunotherapy holds great promise for treating cancer. Nonetheless, T cell-based immunotherapy of solid tumors has remained challenging, largely due to the lack of universal tumor-specific antigens and an immunosuppressive tumor microenvironment (TME) that inhibits lymphocyte infiltration and activation. Aberrant vascularity characterizes malignant solid tumors, which fuels the formation of an immune-hostile microenvironment and induces tumor resistance to immunotherapy, emerging as a crucial target for adjuvant treatment in cancer immunotherapy. In this review, we discuss the molecular and cellular basis of vascular microenvironment-mediated tumor evasion of immune responses and resistance to immunotherapy, with a focus on vessel abnormality, dysfunctional adhesion, immunosuppressive niche, and microenvironmental stress in tumor vasculature. We provide an overview of opportunities and challenges related to these mechanisms. We also propose genetic programming of tumor endothelial cells as an alternative approach to recondition the vascular microenvironment and to overcome tumor resistance to immunotherapy.

Simulated Galactic Cosmic Rays Modify Mitochondrial Metabolism in Osteoclasts, Increase Osteoclastogenesis and Cause Trabecular Bone Loss in Mice

Space is a high-stress environment. One major risk factor for the astronauts when they leave the Earth's magnetic field is exposure to ionizing radiation from galactic cosmic rays (GCR). Several adverse changes occur in mammalian anatomy and physiology in space, including bone loss. In this study, we assessed the effects of simplified GCR exposure on skeletal health in vivo. Three months following exposure to 0.5 Gy total body simulated GCR, blood, bone marrow and tissue were collected from 9 months old male mice. The key findings from our cell and tissue analysis are (1) GCR induced femoral trabecular bone loss in adult mice but had no effect on spinal trabecular bone. (2) GCR increased circulating osteoclast differentiation markers and osteoclast formation but did not alter new bone formation or osteoblast differentiation. (3) Steady-state levels of mitochondrial reactive oxygen species, mitochondrial and non-mitochondrial respiration were increased without any changes in mitochondrial mass in pre-osteoclasts after GCR exposure. (4) Alterations in substrate utilization following GCR exposure in pre-osteoclasts suggested a metabolic rewiring of mitochondria. Taken together, targeting radiation-mediated mitochondrial metabolic reprogramming of osteoclasts could be speculated as a viable therapeutic strategy for space travel induced bone loss.

Exploring the Modulatory Effects of Gut Microbiota in Anti-Cancer Therapy

In the recent decade, gut microbiota has received growing interest due to its role in human health and disease. On the one hand, by utilizing the signaling pathways of the host and interacting with the immune system, the gut microbiota is able to maintain the homeostasis in human body. This important role is mainly modulated by the composition of microbiota, as a normal microbiota composition is responsible for maintaining the homeostasis of human body, while an altered microbiota profile could contribute to several pathogenic conditions and may further lead to oncogenesis and tumor progression. Moreover, recent insights have especially focused on the important role of gut microbiota in current anticancer therapies, including chemotherapy, radiotherapy, immunotherapy and surgery. Research findings have indicated a bidirectional interplay between gut microbiota and these therapeutic methods, in which the implementation of different therapeutic methods could lead to different alterations in gut microbiota, and the presence of gut microbiota could in turn contribute to different therapeutic responses. As a result, manipulating the gut microbiota to reduce the therapy-induced toxicity may provide an adjuvant therapy to achieve a better therapeutic outcome. Given the complex role of gut microbiota in cancer treatment, this review summarizes the interactions between gut microbiota and anticancer therapies, and demonstrates the current strategies for reshaping gut microbiota community, aiming to provide possibilities for finding an alternative approach to lower the damage and improve the efficacy of cancer therapy.

Engineered Cells as a Test Platform for Radiohaptens in Pretargeted Imaging and Radioimmunotherapy Applications

Pretargeted imaging and radioimmunotherapy approaches are designed to have superior targeting properties over directly targeted antibodies but impose more complex pharmacology, which hinders efforts to optimize the ligands prior to human applications. Human embryonic kidney 293T cells expressing the humanized single-chain variable fragment (scFv) C825 (huC825) with high-affinity for DOTA-haptens (293T-huC825) in a transmembrane-anchored format eliminated the requirement to use other pretargeting reagents and provided a simplified, accelerated assay of radiohapten capture while offering normalized cell surface expression of the molecular target of interest. Using binding assays, ex vivo biodistribution, and in vivo imaging, we demonstrated that radiohaptens based on benzyl-DOTA and a second generation "Proteus" DOTA-platform effectively and specifically engaged membrane-bound huC825, achieving favorable tumor-to-normal tissue uptake ratios in mice. Furthermore, [⁸⁶Y]Y-DOTA-Bn predicted absorbed dose to critical organs with reasonable accuracy for both [¹⁷⁷Lu]Lu-DOTA-Bn and [²²⁵Ac]Ac-Pr, which highlights the benefit of a dosimetry-based treatment approach.

Rapid Arc-SBRT: Non-invasive immune adjuvant for advanced stage Non-Small Cell Lung Carcinoma

In conjunction with Radio-chemotherapy, pulmonary resection is recommended for early-stage Non-small-cell lung carcinoma but not for advanced-stage NSCLC patients with having high-grade metastatic lesions. In these cases, Rapid Arc-Stereotactic body radiotherapy (Ra-SBRT) technique offers a therapeutic advantage by delivering focal irradiation to metastatic lung lesions and reduces the bystander toxicity to normal tissues. We have previously demonstrated that Ra-SBRT ablates metastatic lesions and induces tumor immune rejection of metastatic tumors by promoting in situ programming of M2 TAM towards M1-TAM and infiltration of Siglec-8+ Eosinophils. Most interestingly, Ra SBRT has very low abscopal impact and spares normal tissues, which are the significant limitations with conventional radiotherapy. In view of this and Immune adjuvant potential of Ra SBRT, it promotes normalization of aberrant vasculature and inhibits the metastatic potential of NSCLC lesions. In view of this we here propose that Ra-SBRT indeed represents an immunogenic approach for the effective management of advanced-stage NSCLC.

Role of nano-sensitizers in radiation therapy of metastatic tumors

Cancer metastasis remains the major cause of global cancer deaths. Radiation therapy remains one of the golden standards for cancer treatment. Nanomedicine based strategies have been designed and developed in order to improve the clinical outcomes of cancer therapy and diagnosis at molecular levels. Over the years, several researchers have shown their interest in using radiosensitizers made of high Z elements. Metal-based nanosystems also play a dual role by enhancing the synergistic effect of cell killing via various biological immune responses. This review summarizes the role of Nano-sensitizers in boosting radiation (ionizing/non-ionizing radiations) induced biological responses in treatment of metastatic cancer models.

Adjuvant therapy for endometrial cancer in the era of molecular classification: radiotherapy, chemoradiation and novel targets for therapy

Endometrial cancer is primarily treated with surgery. Adjuvant treatment strategies for endometrial cancer, such as external beam pelvic radiotherapy, vaginal brachytherapy, chemotherapy, and combined chemotherapy and radiotherapy, have been studied in several randomized trials. Adjuvant treatment is currently based on the presence of clinico-pathological risk factors. Low-risk disease is adequately managed with surgery alone. In high-intermediate risk endometrial cancer, adjuvant vaginal brachytherapy is recommended to maximize local control, with only mild side effects and without impact on quality of life. For high-risk endometrial cancer, recent large randomized trials support the use of pelvic radiotherapy, especially in stage I-II endometrial cancer with risk factors. For women with serous cancers and those with stage III disease, chemoradiation increased both recurrence-free and overall survival, while GOG-258 showed similar recurrence-free survival compared with six cycles of chemotherapy alone, but with better pelvic and para-aortic nodal control with combined chemotherapy and radiotherapy. Recent molecular studies, most notably the work from The Cancer Genome Atlas (TCGA) project, have shown that four endometrial cancer molecular classes can be distinguished; POLE ultra-mutated, microsatellite instable hypermutated, copy-number-low, and copy-number-high. Subsequent studies, using surrogate markers to identify groups analogous to TCGA sub-classes, showed that all four endometrial cancer sub-types are found across all stages, histological types, and grades. Moreover, the molecular sub-groups have proved to have a stronger prognostic impact than histo-pathological tumor characteristics. This introduces an new era of molecular classification based diagnostics and treatment approaches. Integration of the molecular factors and new therapeutic targets will lead to molecular-integrated adjuvant treatment including targeted treatments, which are the rationale of new and ongoing trials. This review presents an overview of current adjuvant treatment strategies in endometrial cancer, highlights the development and evaluation of a molecular-integrated risk profile, and briefly discusses ongoing developments in targeted treatment.

Immunoadjuvants for cancer immunotherapy: A review of recent developments

Cancer immunotherapy evolved as a new treatment modality to eradicate tumor cells and has gained in popularity after its successful clinical transition. By activating antigen-presenting cells (APCs), and thus, inducing innate or adaptive immune responses, immunoadjuvants have become promising tools for cancer immunotherapy. Different types of immunoadjuvants such as toll-like receptor (TLR) agonists, exosomes, and metallic and plant-derived immunoadjuvants have been studied for their immunological effects. However, the clinical use of immunoadjuvants is limited by short response rates and various side-effects. The rapid progress made in the development of nanoparticle systems as immunoadjuvant carrier vehicles has provided potential carriers for cancer immunotherapy. In this review article, we describe different types of immunoadjuvants, their limitations, modes of action, and the reasons for their clinical adoption. In addition, we review recent progress made in the nanoparticle-based immunoadjuvant field and on the combined use of nanoparticle-based immunoadjuvants and chemotherapy, phototherapy, radiation therapy, and immune checkpoint inhibitor-based therapy. STATEMENT OF SIGNIFICANCE: Cancer immunotherapy emerged as a new hope for treating malignant tumors. Different types of immunoadjuvants serve as an important tool for cancer immunotherapy by activating an innate or adaptive immune response. Limitation of free immunoadjuvant has paved the path for the development of nanoparticle-based immunoadjuvant therapy with the hope of prolonging the therapeutic efficacy. This review highlights the recent advancement made in nanoparticle-based immunoadjuvant therapy in modulating the adaptive and innate immune system. The application of the combinatorial approach of chemotherapy, phototherapy, radiation therapy adds synergy in nanoparticle-based immunoadjuvant therapy. It will broaden the reader's understanding on the recent progress made in immunotherapy with the aid of immunoadjuvant-based nanosystem.

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.

The Influence of Radiation on Bone and Bone Cells-Differential Effects on Osteoclasts and Osteoblasts

The bone is a complex organ that is dependent on a tight regulation between bone formation by osteoblasts (OBs) and bone resorption by osteoclasts (OCs). These processes can be influenced by environmental factors such as ionizing radiation (IR). In cancer therapy, IR is applied in high doses, leading to detrimental effects on bone, whereas radiation therapy with low doses of IR is applied for chronic degenerative and inflammatory diseases, with a positive impact especially on bone homeostasis. Moreover, the effects of IR are of particular interest in space travel, as astronauts suffer from bone loss due to space radiation and microgravity. This review summarizes the current state of knowledge on the effects of IR on bone with a special focus on the influence on OCs and OBs, as these cells are essential in bone remodeling. In addition, the influence of IR on the bone microenvironment is discussed. In summary, the effects of IR on bone and bone remodeling cells strongly depend on the applied radiation dose, as differential results are provided from in vivo as well as in vitro studies with varying doses of IR. Furthermore, the isolated effects of IR on a single cell type are difficult to determine, as the bone cells and bone microenvironment are building a tightly regulated network, influencing on one another. Therefore, future research is necessary in order to elucidate the influence of different bone cells on the overall radiation-induced effects on bone.

Systemic Inflammation After Radiation Predicts Locoregional Recurrence, Progression, and Mortality in Stage II-III Triple-Negative Breast Cancer

PURPOSE

Patients with triple-negative breast cancer experience high rates of recurrence after radiation, which may be facilitated by the recruitment of circulating tumor cells to proinflammatory microenvironments in the absence of lymphocytes. We hypothesized that patients with lymphopenia and elevated inflammatory hematologic markers after radiation therapy would have an increased risk of locoregional failure.

METHODS AND MATERIALS

With approval, we retrospectively studied a cohort of women treated with adjuvant radiation therapy for stage II-III triple-negative breast cancer. We analyzed the relationship between post-radiation therapy neutrophil:lymphocyte ratio (NLR) and locoregional recurrence by using Cox regression.

RESULTS

One-hundred thirty patients met inclusion criteria, and median follow-up time was 7.6 years. Patients with an NLR ≥3 had a higher rate of locoregional failure (P = .04) and lower overall survival (P = .04). After adjusting for stage (hazard ratio [HR], 5.5; P < .0001) and neoadjuvant chemotherapy (HR, 2.5; P = .0162), NLR was highly predictive of locoregional failure (HR, 1.4; P = .0009). NLR was also highly predictive of overall survival (HR, 1.3; P = .0007) after adjustment for stage and neoadjuvant chemotherapy.

CONCLUSIONS

Innate peripheral inflammation after radiation therapy for triple-negative breast cancer in an immunocompromised setting may be a novel prognostic biomarker for locoregional recurrence, progression, and survival. This finding supports preclinical studies of post-radiation therapy inflammation-mediated tumor progression. Further studies are needed to confirm this finding and develop treatment strategies.

Addition of Radiotherapy to Immunotherapy: Effects on Outcome of Different Subgroups Using a Propensity Score Matching

Immune checkpoint inhibition (ICI) has been established as successful modality in cancer treatment. Combination concepts are used to optimize treatment outcome, but may also induce higher toxicity rates than monotherapy. Several rationales support the combination of radiotherapy (RT) with ICI as radioimmunotherapy (RIT), but it is still unknown in which clinical situation RIT would be most beneficial. Therefore, we have conducted a retrospective matched-pair analysis of 201 patients with advanced-stage cancers and formed two groups treated with programmed cell death protein 1 (PD-1) inhibitors only (PD1i) or in combination with local RT (RIT) at our center between 2013 and 2017. We collected baseline characteristics, programmed death ligand 1 (PD-L1) status, mutational status, PD-1 inhibitor and RT treatment details, and side effects according to the Common Terminology Criteria for Adverse Events (CTCAE) v.5.0. Patients received pembrolizumab (n = 93) or nivolumab (n = 108), 153 with additional RT. For overall survival (OS) and progression-free survival (PFS), there was no significant difference between both groups. After propensity score matching (PSM), we analyzed 96 patients, 67 with additional and 29 without RT. We matched for different covariates that could have a possible influence on the treatment outcome. The RIT group displayed a trend towards a longer OS until the PD1i group reached a survival plateau. PD-L1-positive patients, smokers, patients with a BMI ≤ 25, and patients without malignant melanoma showed a longer OS when treated with RIT. Our data show that some subgroups may benefit more from RIT than others. Suitable biomarkers as well as the optimal timing and dosage must be established in order to achieve the best effect on cancer treatment outcome.

Immunotherapy in cervix cancer

The treatment approach to cervix cancer has remained unchanged for several decades and new therapeutic strategies are now required to improve outcomes, as the prognosis is still poor. In the last years, a better understanding of HPV tumor-host immune system interactions and the development of new therapeutics targeting immune checkpoints generated interest in the use of immunotherapy in cervix cancer. Preliminary phase I-II trials demonstrated the efficacy, the duration of responses and the manageable safety of this approach. Currently, many phase II and III studies are ongoing in both locally advanced and metastatic cervical cancer, assessing immunotherapy as a single agent or in combination with chemotherapy and radiotherapy. We reviewed the published data and the therapeutic implications of the most promising novel immunotherapeutic agents under investigation in cervix cancer.

Gut microbiota modulate dendritic cell antigen presentation and radiotherapy-induced antitumor immune response

Alterations in gut microbiota impact the pathophysiology of several diseases, including cancer. Radiotherapy (RT), an established curative and palliative cancer treatment, exerts potent immune modulatory effects, inducing tumor-associated antigen (TAA) cross-priming with antitumor CD8+ T cell elicitation and abscopal effects. We tested whether the gut microbiota modulates antitumor immune response following RT distal to the gut. Vancomycin, an antibiotic that acts mainly on gram-positive bacteria and is restricted to the gut, potentiated the RT-induced antitumor immune response and tumor growth inhibition. This synergy was dependent on TAA cross presentation to cytolytic CD8+ T cells and on IFN-γ. Notably, butyrate, a metabolite produced by the vancomycin-depleted gut bacteria, abrogated the vancomycin effect. In conclusion, depletion of vancomycin-sensitive bacteria enhances the antitumor activity of RT, which has important clinical ramifications.

Multiple Dynamics in Tumor Microenvironment Under Radiotherapy

The tumor microenvironment (TME) is an evolutionally low-level and embryonically featured tissue comprising heterogenic populations of malignant and stromal cells as well as noncellular components. Under radiotherapy (RT), the major modality for the treatment of malignant diseases [1], TME shows an adaptive response in multiple aspects that affect the efficacy of RT. With the potential clinical benefits, interests in RT combined with immunotherapy (IT) are intensified with a large scale of clinical trials underway for an array of cancer types. A better understanding of the multiple molecular aspects, especially the cross talks of RT-mediated energy reprogramming and immunoregulation in the irradiated TME (ITME), will be necessary for further enhancing the benefit of RT-IT modality. Coming studies should further reveal more mechanistic insights of radiation-induced instant or permanent consequence in tumor and stromal cells. Results from these studies will help to identify critical molecular pathways including cancer stem cell repopulation, metabolic rewiring, and specific communication between radioresistant cancer cells and the infiltrated immune active lymphocytes. In this chapter, we will focus on the following aspects: radiation-repopulated cancer stem cells (CSCs), hypoxia and re-oxygenation, reprogramming metabolism, and radiation-induced immune regulation, in which we summarize the current literature to illustrate an integrated image of the ITME. We hope that the contents in this chapter will be informative for physicians and translational researchers in cancer radiotherapy or immunotherapy.

Damage-associated molecular patterns in tumor radiotherapy

Radiotherapy is one of the most common modalities for the treatment of cancer. One of the most promising effects of radiotherapy is immunologic cell death and the release of danger alarms, which are known as damage-associated molecular patterns (DAMPs). DAMPs are able to trigger cancer cells and other cells within tumor microenvironment (TME), either for suppression or promotion of tumor growth. Heat shock proteins (HSPs) including HSP70 and HSP90, high mobility group box 1 (HMGB1), and adenosine triphosphate (ATP) and its metabolites such as adenosine are the most common danger alarms that are released after radiotherapy-induced immunologic cell death. Some DAMPs including adenosine is able to interact with both cancer cells as well as other cells in TME to promote tumor growth and resistance to radiotherapy. However, others are able to trigger anti-tumor immunity or both tumor suppressive and immunosuppressive mechanisms depending on affected cells. In this review, we explain the mechanisms behind the release of radiation-induced DAMPs, and its consequences on cells within tumor. Targeting of these mechanisms may be in favor of tumor control in combination with radiotherapy and radioimmunotherapy.

Mitigating Coronavirus-Induced Acute Respiratory Distress Syndrome by Radiotherapy

The acute respiratory distress syndrome (ARDS) induced by SARS-CoV-2-mediated cytokine storm (CS) in lungs leads to the high mortality in COVID-19 patients. To reduce ARDS, an ideal approach is to diminish virus loading by activating immune cells for CS prevention or to suppress the overactive cytokine-releasing immune cells for CS inhibition. Here, a potential radiation-mediated CS regulation is raised by reevaluating the radiation-mediated pneumonia control in the 1920s, with the following latent advantages of lung radiotherapy (LR) in treatment of COVID-19: (1) radiation accesses poorly circulated tissue more efficiently than blood-delivered medications; (2) low-dose radiation (LDR)-mediated metabolic rewiring and immune cell activation inhibit virus loading; (3) pre-consumption of immune reserves by LDR decreases CS severity; (4) higherdose radiation (HDR) within lung-tolerable doses relieves CS by eliminating in situ overactive cytokine-releasing cells. Thus, LDR and HDR or combined with antiviral and life-supporting modalities may mitigate SARS-CoV-2 and other virus-mediated ARDS.

Differences of the Immune Phenotype of Breast Cancer Cells after Ex Vivo Hyperthermia by Warm-Water or Microwave Radiation in a Closed-Loop System Alone or in Combination with Radiotherapy

The treatment of breast cancer by radiotherapy can be complemented by hyperthermia. Little is known about how the immune phenotype of tumor cells is changed thereby, also in terms of a dependence on the heating method. We developed a sterile closed-loop system, using either a warm-water bath or a microwave at 2.45 GHz to examine the impact of ex vivo hyperthermia on cell death, the release of HSP70, and the expression of immune checkpoint molecules (ICMs) on MCF-7 and MDA-MB-231 breast cancer cells by multicolor flow cytometry and ELISA. Heating was performed between 39 and 44 °C. Numerical process simulations identified temperature distributions. Additionally, irradiation with 2 × 5 Gy or 5 × 2 Gy was applied. We observed a release of HSP70 after hyperthermia at all examined temperatures and independently of the heating method, but microwave heating was more effective in cell killing, and microwave heating with and without radiotherapy increased subsequent HSP70 concentrations. Adding hyperthermia to radiotherapy, dynamically or individually, affected the expression of the ICM PD-L1, PD-L2, HVEM, ICOS-L, CD137-L, OX40-L, CD27-L, and EGFR on breast cancer cells. Well-characterized pre-clinical heating systems are mandatory to screen the immune phenotype of tumor cells in clinically relevant settings to define immune matrices for therapy adaption.

Identifying the Optimal Fractionation Schedules for Improved Response Rates and Survival in Patients with Metastatic Melanoma Treated with Ipilimumab and Radiotherapy

Objective:

There is a growing body of evidence that combining ipilimumab with higher doses of radiotherapy may improve the response rates and survival in patients with metastatic melanoma compared to lower doses of radiotherapy. However, the dose cutoff at which improved outcomes are more likely to occur has not been properly identified.

Methods:

We conducted a retrospective analysis of 100 patients treated with ipilimumab and radiotherapy for metastatic melanoma at a single institution from May 2011 to January 2017. Demographic, clinical, and treatment factors, including the biological equivalent dose (BED) with an α/β of 7, were recorded. Endpoints of interest included infield and global complete response (CR) after the completion of radiation and ipilimumab based on the RECIST criteria (v1.1) and 12-month overall survival (OS).

Results:

The BED cutoffs at which improved outcomes are more likely to occur are 46.5 Gy for infield CR, 50.9 Gy for global CR, and 46.5 Gy for 12 month OS. The least aggressive fractionation schedules used in this patient population that have a BED above the threshold for all 3 outcomes include 40 Gy in 20 fractions, 30 Gy in 6 fractions, and 24 Gy in 3 fractions.

Conclusion:

This hypothesis-generating study suggests that patients who cannot receive ablative intent radiotherapy may be more likely to benefit from concurrent radiotherapy with ipilimumab if their fractionation schedule has a BED above 46.5 - 50.9 Gy. Prospective trials evaluating this question should be considered.

The Abscopal Effect in the Era of Cancer Immunotherapy: a Spontaneous Synergism Boosting Anti-tumor Immunity?

Radiotherapy is one of the main treatment strategies used in cancer. Aside from the local control of the disease, which is mediated by a direct cytotoxic effect on tumor cells, radiotherapy has also been shown to exert immune-mediated local and systemic effects. Radiotherapy can elicit anti-tumor responses in distant sites from the radiation field; this phenomenon is known as the abscopal effect and has been described in patients previously treated with immune checkpoint blockade (ICB). Considering that the efficacy of immunotherapy has been demonstrated only in a subset of patients-who often benefit with lasting responses-efforts are ongoing to potentiate its activity with the development of new combination strategies. Radiotherapy might represent a potential candidate for a synergistic combination with immunotherapy, by improving the immunogenicity of tumors and by enhancing local and systemic immune effects. This review aims to summarize the current pre-clinical and clinical data on the immune effects of radiotherapy and their potential implications for cancer immunotherapy.

Challenges and Prospects of Chimeric Antigen Receptor T-cell Therapy for Metastatic Prostate Cancer

CONTEXT

Progress achieved in the treatment of prostate cancer (PCa) with surgical, radiation, and hormonal therapies has drastically reduced mortality from this disease. Yet, patients with advanced PCa have few, if any, curative options. Recent success in treating patients with hematological malignancies of B-cell origin using T cells engineered to express chimeric antigen receptors (CARs) has inspired multiple groups worldwide to adapt this approach to the problem of late-stage PCa.

OBJECTIVE

To summarize the available clinical results for CAR T-cell therapy of PCa and discuss future technological advancements in the CAR T-cell field that may help patients with metastatic PCa.

EVIDENCE ACQUISITION

A literature review was conducted of clinical trial data, abstracts presented at recent oncology conferences, as well as reports highlighting critical bottlenecks of CAR T-cell therapy that became apparent from preclinical and clinical studies.

EVIDENCE SYNTHESIS

Current understanding of why CAR T-cell therapy may fail, particularly in the context of solid cancers, is as follows. First, a CAR design that provides potent activity and persistence of engineered T cells in the hostile tumor microenvironment is a must. The choice of the targetable epitope(s) is critical to counteract tumor antigen escape. Preclinical and clinical evidence indicates that the efficacy of CAR T-cell therapy can be enhanced significantly in combination with other therapeutic approaches. We propose that several improvements to CAR design and patient conditioning, such as unbiased identification of novel PCa-specific CAR targets, use of next-generation (multispecific, resistant to the tumor microenvironment, and with prolonged persistence) CAR T-cell products, and combination therapies may translate into improved patient outcomes and more durable responses.

CONCLUSIONS

Although significant preclinical experience of testing CAR T cells in solid cancer models has identified important technological and biological bottlenecks, information from clinical trials, particularly those focusing on the PCa, will be instrumental to the rational design of advanced CAR T therapies that will be both safe and effective in patients with advanced PCa.

PATIENT SUMMARY

So far, chimeric antigen receptor (CAR) T-cell therapy has not shown significant activity in patients with metastatic prostate cancer (PCa). CAR T-cell products used for such trials represent one of the pioneering efforts to adapt this technology to the problem of metastatic PCa. In retrospect, both CAR design and cell composition appear to have been suboptimal to expect strong patient responses. Given the impressive results of CAR-based approaches observed in preclinical models of solid cancers, emerging CAR T-cell products are expected to be more successful in the clinic. Here, we discuss the challenges that need to be overcome to boost the efficacy of PCa-targeted CAR T-cell therapy and call for dialogue between clinicians and cell biologists to address these challenges.

Increased PD-L1 expression in radioresistant HNSCC cell lines after irradiation affects cell proliferation due to inactivation of GSK-3beta

At present, targeting PD-1/PD-L1 axis for immune checkpoint inhibition has improved treatment of various tumor entities, including head and neck squamous cell carcinoma (HNSCC). However, one part of the patient cohort still shows little improvement or even hyperprogression. We established three radioresistant (RR) and three radiosensitive (RS) HNSCC cell lines. RR cells showed prolonged survival as well as delayed and diminished apoptosis after irradiation with vimentin expression but no E-cadherin expression, whereas RS cell lines died early and exhibited early apoptosis after irradiation and high vimentin expression. Here, we present results demonstrating differential basal PD-L1 gene and protein expression in RR and RS HNSCC cell lines. Moreover, we observed a radiation dose dependent increase of total PD-L1 protein expression in RR cell lines up to 96h after irradiation compared to non-irradiated (non-IRR) cells. We found a significant GSK-3beta phosphorylation, resulting in an inactivation, after irradiation of RR cell lines. Co-immunoprecipitation experiments revealed decreased interaction of GSK-3beta with PD-L1 in non-IRR compared to irradiated (IRR) RR cells leading to PD-L1 stabilization in RR cells. PD-L1 knockdown in RR cells showed a strong decrease in cell survival. In summary, our results suggest an irradiation dependent increase in basal PD-L1 expression in RR HNSCC cell lines via GSK-3beta inactivation.

Radiotherapy and immune response: the systemic effects of a local treatment

Technological developments have allowed improvements in radiotherapy delivery, with higher precision and better sparing of normal tissue. For many years, it has been well known that ionizing radiation has not only local action but also systemic effects by triggering many molecular signaling pathways. There is still a lack of knowledge of this issue. This review focuses on the current literature about the effects of ionizing radiation on the immune system, either suppressing or stimulating the host reactions against the tumor, and the factors that interact with these responses, such as the radiation dose and dose / fraction effects in the tumor microenvironment and vasculature. In addition, some implications of these effects in cancer treatment, mainly in combined strategies, are addressed from the perspective of their interactions with the more advanced technology currently available, such as heavy ion therapy and nanotechnology.

Low-Dose Radiotherapy Has No Harmful Effects on Key Cells of Healthy Non-Inflamed Joints

Low-dose radiotherapy (LD-RT) for benign inflammatory and/or bone destructive diseases has been used long. Therefore, mechanistic investigations on cells being present in joints are mostly made in an inflammatory setting. This raises the question whether similar effects of LD-RT are also seen in healthy tissue and thus might cause possible harmful effects. We performed examinations on the functionality and phenotype of key cells within the joint, namely on fibroblast-like synoviocytes (FLS), osteoclasts and osteoblasts, as well as on immune cells. Low doses of ionizing radiation showed only a minor impact on cytokine release by healthy FLS as well as on molecules involved in cartilage and bone destruction and had no significant impact on cell death and migration properties. The bone resorbing abilities of healthy osteoclasts was slightly reduced following LD-RT and a positive impact on bone formation of healthy osteoblasts was observed after in particular exposure to 0.5 Gray (Gy). Cell death rates of bone-marrow cells were only marginally increased and immune cell composition of the bone marrow showed a slight shift from CD8⁺ to CD4⁺ T cell subsets. Taken together, our results indicate that LD-RT with particularly a single dose of 0.5 Gy has no harmful effects on cells of healthy joints.

Chimeric Antigen Receptor T Cell Therapy: Challenges to Bench-to-Bedside Efficacy

Immunotherapy with T cells genetically modified to express chimeric Ag receptors (CARs) that target tumor-associated molecules have impressive efficacy in hematological malignancies. The field has now embraced the challenge of applying this approach to treat common epithelial malignancies, which make up the majority of cancer cases but evade immunologic attack by a variety of subversive mechanisms. In this study, we review the principles that have guided CAR T cell design and the extraordinary clinical results being achieved in B cell malignancies targeting CD19 with a single infusion of engineered T cells. This success has raised expectations that CAR T cells can be applied to solid tumors, but numerous obstacles must be overcome to achieve the success observed in hematologic cancers. Potential solutions driven by advances in genetic engineering, synthetic biology, T cell biology, and improved tumor models that recapitulate the obstacles in human tumors are discussed.

Combination Treatment of Stereotactic Body Radiation Therapy and Immature Dendritic Cell Vaccination for Augmentation of Local and Systemic Effects

PURPOSE

The purpose of this study was to investigate the efficacy of stereotactic body radiation therapy (SBRT) as a tumor-associated antigen (TAA) presentation method for dendritic cell (DC) sensitization and evaluate its effect in combination with immunotherapy using an intratumoral injection of immature DCs (iDCs).

Methods and Materials

CT-26 colon carcinoma cell was used as a cancer cell line. Annexin V staining and phagocytosis assays were performed to determine the appropriate radiation dose and incubation time to generate TAAs. BALB/c mice were used for in vivo experiments. Cancer cells were injected into the right legs and left flanks to generate primary and metastatic tumors, respectively. The mice were subjected to radiation therapy (RT) alone, intradermal injection of electroporated DCs alone, or RT in combination with iDC intratumoral injection (RT/iDC). Tumor growth measurement and survival rate analysis were performed. Enzyme-linked immunospot and cytotoxicity assays were performed to observe the effect of different treatments on the immune system.

RESULTS

Annexin V staining and phagocytosis assays showed that 15 Gy radiation dose and 48 hours of incubation was appropriate for subsequent experiments. Maximum DC sensitization and T-cell stimulation was observed with RT as compared to other TAA preparation methods. In vivo assays revealed statistically significant delay in the growth of both primary and metastatic tumors in the RT/iDC group. The overall survival rate was the highest in the RT/iDC group.

CONCLUSION

The combination of SBRT and iDC vaccination may enhance treatment effects. Clinical trials and further studies are warranted in the future.

Immunotherapy with radiotherapy in urological malignancies

PURPOSE OF REVIEW

Radiotherapy has the potential to augment the host's immune response to cancer. Urological malignancies are highly immunogenic and the combination of radiotherapy and immunotherapy shows promise. In this review, we discuss the effects of radiotherapy on the cancer immune system and highlight the rationale for using the combined approach in prostate, urothelial and renal cancers. Current clinical studies are summarized emphasising the synergistic effects of the combination and the possibility of improved clinical outcomes.

RECENT FINDINGS

Local and abscopal effects have been observed in different urological cancers when using a combined approach. Large fraction size is associated with an increased immune response. Multiple radiotherapy/immunotherapy combinations are being studied in several clinical trials although no combination has yet been introduced in to standard practice.

SUMMARY

Although our knowledge of immunomodulation by radiotherapy has improved significantly in recent times, there remain several unanswered questions regarding how to best use the combination in clinical practice. Ongoing trials will provide further insight into complex mechanisms governing radiotherapy-immunotherapy interactions, with potential to improve clinical outcomes.

Immune modulatory effects of radiotherapy as basis for well-reasoned radioimmunotherapies

BACKGROUND

Radiotherapy (RT) has been known for decades as a local treatment modality for malign and benign disease. In order to efficiently exploit the therapeutic potential of RT, an understanding of the immune modulatory properties of ionizing radiation is mandatory. These should be used for improvement of radioimmunotherapies for cancer in particular.

METHODS

We here summarize the latest research and review articles about immune modulatory properties of RT, with focus on radiation dose and on combination of RT with selected immunotherapies. Based on the knowledge of the manifold immune mechanisms that are triggered by RT, thought-provoking impulse for multimodal radioimmunotherapies is provided.

RESULTS

It has become obvious that ionizing radiation induces various forms of cell death and associated processes via DNA damage initiation and triggering of cellular stress responses. Immunogenic cell death (ICD) is of special interest since it activates the immune system via release of danger signals and via direct activation of immune cells. While RT with higher single doses in particular induces ICD, RT with a lower dose is mainly responsible for immune cell recruitment and for attenuation of an existing inflammation. The counteracting immunosuppression emanating from tumor cells can be overcome by combining RT with selected immunotherapies such as immune checkpoint inhibition, TGF-β inhibitors, and boosting of immunity with vaccination.

CONCLUSION

In order to exploit the full power of RT and thereby develop efficient radioimmunotherapies, the dose per fraction used in RT protocols, the fractionation, the quality, and the quantity of certain immunotherapies need to be qualitatively and chronologically well-matched to the individual immune status of the patient.

A Co-culture Method to Investigate the Crosstalk Between X-ray Irradiated Caco-2 Cells and PBMC

The protocol adopted in this work aims at unraveling how X-rays perturb the functioning of the intestinal barrier, focusing on the interplay between colorectal tumor cells and the immune system. Colorectal carcinoma is among the most common type of cancer, typically treated by surgery, chemotherapy, and radiotherapy. Advantages of radiotherapy in targeting the tumor are well known. However, even limited exposures of healthy tissues are of great concern, particularly regarding the effects on the intestinal barrier and the immune system. The adopted setup allows to study the interplay between two cell populations in a condition more similar to the physiological one, when compared to normal cell cultures. For this purpose, we resort to different techniques and we used an in vitro co-culture model, based on Caco-2 cells differentiated as a monolayer and PBMC, sharing the same culture medium. This protocol has been developed to focus on both macroscopic effects, i.e. cell viability and Trans-Epithelial Electrical Resistance (TEER), and, through western blot, molecular alterations, i.e. the activation of inflammatory pathway in immune cells and the tight junction protein expression in Caco-2 cells. Initial evaluation of radiation effects on Caco-2 cell viability was assessed via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Trypan blue assays, while TEER was measured at fixed time intervals through an ohmmeter specifically designed for co-culture systems. In this way, the effects due to radiation, the presence of Peripheral Blood Mononuclear Cells (PBMC), and eventually their synergistic effect, can be demonstrated. Through these complementary techniques, we observed a high radio-resistance of Caco-2 within the range of 2 - 10 Gy of X-rays and an increased Caco-2 monolayer permeability when PBMCs were added. In particular, PBMC presence was found to be associated with the variation in the tight junction scaffold proteins expression.

Program death inhibitors in classical Hodgkin's lymphoma: a comprehensive review

Cancer cells are able to induce immune system tolerance through different mechanisms. Recent achievements in the understanding of tumor microenvironment, invasion, and metastasizing have contributed to accelerated drug developments and approvals. Hodgkin lymphoma (HL) cells are the minority in a lymphocyte-rich microenvironment of HL tissue. The program death-1 (PD-1)/PD-ligand-1 checkpoint is one of the known effective pathways in classical HL to escape the immune system cells. The approval of PD-1 inhibitors in different cancer types with exciting response rates is truly revolutionizing our treatment armamentarium against cancer in general and classical HL in specific. Although the disease is one of the most curable tumors, we still need better outcome with more gentle treatment, especially for relapsed and refractory (r/r) patients. In this article, we review the current literature on immune checkpoint inhibitors and currently ongoing studies with nivolumab and pembrolizumab in r/r classical HL.

Modulated electro-hyperthermia induced loco-regional and systemic tumor destruction in colorectal cancer allografts

Background: Modulated electro-hyperthermia (mEHT), a non-invasive intervention using 13.56 MHz radiofrequency, can selectively target cancers due to their elevated glycolysis (Warburg-effect), extracellular ion concentration and conductivity compared to normal tissues. We showed earlier that mEHT alone can provoke apoptosis and damage associated molecular pattern (DAMP) signals in human HT29 colorectal cancer xenografts of immunocompromised mice. Materials: Here we tested the mEHT induced stress and immune responses in C26 colorectal cancer allografts of immunocompetent (BALB/c) mice between 12-72 h post-treatment. The right side of the symmetrical tumors grown in both femoral regions of mice were treated for 30 minutes, while the left side tumors served for untreated controls. Results: Loco-regional mEHT treatment induced an ongoing and significant tumor damage with the blockade of cell cycle progression indicated by the loss of nuclear Ki67 protein. Nuclear shrinkage, apoptotic bodies and DNA fragmentation detected using TUNEL assay confirmed apoptosis. Cleaved/activated-caspase-8 and -caspase-3 upregulation along with mitochondrial translocation of bax protein and release of cytochrome-c were consistent with the activation of both the extrinsic and intrinsic caspase-dependent programmed cell death pathways. The prominent release of stress-associated Hsp70, calreticulin and HMGB1 proteins, relevant to DAMP signaling, was accompanied by the significant tumor infiltration by S100 positive antigen presenting dendritic cells and CD3 positive T-cells with only scant FoxP3 positive regulatory T-cells. In addition, mEHT combined with a chlorogenic acid rich T-cell promoting agent induced significant cell death both in the treated and the untreated contralateral tumors indicating a systemic anti-tumor effect. Conclusions: mEHT induced caspase-dependent programmed cell death and the release of stress associated DAMP proteins in colorectal cancer allografts can provoke major immune cell infiltration. Accumulating antigen presenting dendritic cells and T-cells are likely to contribute to the ongoing tumor destruction by an immunogenic cell death mechanism both locally and through systemic effect at distant tumor sites.

Combining radiotherapy and ipilimumab induces clinically relevant radiation-induced abscopal effects in metastatic melanoma patients: A systematic review

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Radiotherapy plus ipilimumab increases abscopal responses in metastatic melanoma patients.

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Radiotherapy plus ipilimumab improves the OS in metastatic melanoma patients.

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Radiotherapy plus ipilimumab does not increase toxicity in metastatic melanoma patients.

Background

In the last years, limited studies have described that radiotherapy could produce important distant responses in unirradiated sites, the so-called “abscopal effect”. Recent evidence suggests that radiotherapy induces antigen release from tumor, in this way activating the immune system. However, radiotherapy alone is rarely enough to induce the systemic response requested for control of the metastases. With the advent of immunotherapy, the immune checkpoint inhibitors (ICI) have demonstrated impressive efficacy in various metastatic cancers. Currently, preclinical and clinical studies have reported a significant increase of abscopal responses in patients treated with the combination of radiotherapy and ICI. The purpose of this review was summarizing the clinical studies combining radiotherapy and ipilimumab (ipi), particularly focusing on abscopal responses.

Methods and Materials

Databases of Medline (via Pubmed) from 2009 to June 2, 2017 were reviewed to obtain English language studies reporting clinical abscopal effect in the combination of radiotherapy with exclusive ipi in metastatic melanoma cancers. Included studies reported the abscopal effect as a primary endpoint, and as secondary endpoint included overall survival and toxicity.

Results

A total of 16 studies met the inclusion criteria. These studies included a total of 451 patients, and in 5/16 studies the patients were treated on research protocols and followed-up prospectively. The median reported abscopal effect and OS were 26.5% and 19 months, respectively. The median toxicity ≥ Grade 3 was 18.3% ranged from 10% to 20%.

Conclusion

Early clinical outcomes reports suggest that the combination of ipilimumab and RT may improve survival in metastatic melanoma patients. The abscopal responses become a clinically relevant effect of such combination and should be studied in controlled randomized trials.

Microsatellite stability and mismatch repair proficiency in nasopharyngeal carcinoma may not predict programmed death-1 blockade resistance

The US FDA granted accelerated approval to pembrolizumab for microsatellite instability-high and mismatch repair deficient cancers. The response of programmed death-1 blockade in mismatch repair proficiency (pMMR) colorectal cancer is very poor, however, whether such treatment is effective in pMMR nasopharyngeal carcinoma (NPC) remains unknown.

We report a case of a 51-year-old man with NPC. PET-CT scan revealed a space-occupying lesion in the left lung, and the pathologic result confirmed the occupying lesion originated from NPC. Meanwhile, both immunohistochemistry and PCR revealed that the occupying lesion belonged to pMMR NPC. The lung lesions largely shrunk after chemoradiotherapy. One year later, MRI showed brain occupancy, and brain lesion resection surgery was performed subsequently. The resected tissue was also validated to be the metastatic lesion from NPC. After one month, the patient was examined again by PET-CT, which showed multiple metastases in the liver, pelvis and adrenal gland. Since January 2017, the patient has been treated with pembrolizumab therapy. After five courses of treatment, both PET-CT and blood testing were repeated and demonstrated that metastases and serum Epstein-Barr virus DNA almost completely disappeared.

We provide the first report that pembrolizumab has a confirmed objective response to microsatellite stability and pMMR NPC, and two biomarkers may not be sufficient to identify patients who might be resistant to such treatment in NPC.