Unlocking the combination: potentiation of radiation-induced antitumor responses with immunotherapy

Clinical application of 192Ir High-Dose-Rate brachytherapy in metastatic lymph nodes of the neck

OBJECTIVE

The objective of this study was to investigate the safety and effectiveness of high-dose-rate brachytherapy as a treatment modality for recurrent or residual neck metastatic lymph nodes following external radiotherapy.

METHODS

38 patients with 52 metastatic lymph nodes recurring or residual after previous external radiotherapy was completed to metastatic lymph nodes in the neck were collected from January 2019 to February 2022. High-dose-rate brachytherapy with 192Ir was performed with a prescribed dose of 20-30 Gy/1f (effective biological dose of 60-120 Gy), and imaging was performed at 1, 3, and 6 months after treatment to assess the local control rate and adverse effects of treatment.

RESULTS

All 38 patients received completed treatment, and they were followed up for 6 months. 52 patients with neck lymph node metastases had an objective response rate. (Complete response, CR + Partial response, PR) of 76.9%, which comprised 89.5% (34/38) for lymph nodes ≤ 3 cm and 42.9% (4/14) for > 3 cm, P = 0.028. P > 0.05 for CR + PR versus stable disease, SD + progressive disease, PD for lymph nodes between different subdivisions of the neck. Using the Radiation Therapy Oncology Group (RTOG) Acute Toxicity Scoring System, there were 6 cases of acute radioskin injuries of degree I and 4 cases of degree II with a 60% symptomatic relief rate.

CONCLUSIONS

High-dose-rate brachytherapy serves as a safe and effective method in treating recurrent residual neck metastatic lymph nodes in the field after external radiotherapy, exerting tolerable adverse effects.

Dual effects of radiotherapy on tumor microenvironment and its contribution towards the development of resistance to immunotherapy in gastrointestinal and thoracic cancers

Successful clinical methods for tumor elimination include a combination of surgical resection, radiotherapy, and chemotherapy. Radiotherapy is one of the crucial components of the cancer treatment regimens which allow to extend patient life expectancy. Current cutting-edge radiotherapy research is focused on the identification of methods that should increase cancer cell sensitivity to radiation and activate anti-cancer immunity mechanisms. Radiation treatment activates various cells of the tumor microenvironment (TME) and impacts tumor growth, angiogenesis, and anti-cancer immunity. Radiotherapy was shown to regulate signaling and anti-cancer functions of various TME immune and vasculature cell components, including tumor-associated macrophages, dendritic cells, endothelial cells, cancer-associated fibroblasts (CAFs), natural killers, and other T cell subsets. Dual effects of radiation, including metastasis-promoting effects and activation of oxidative stress, have been detected, suggesting that radiotherapy triggers heterogeneous targets. In this review, we critically discuss the activation of TME and angiogenesis during radiotherapy which is used to strengthen the effects of novel immunotherapy. Intracellular, genetic, and epigenetic mechanisms of signaling and clinical manipulations of immune responses and oxidative stress by radiotherapy are accented. Current findings indicate that radiotherapy should be considered as a supporting instrument for immunotherapy to limit the cancer-promoting effects of TME. To increase cancer-free survival rates, it is recommended to combine personalized radiation therapy methods with TME-targeting drugs, including immune checkpoint inhibitors.

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

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

Focused Ultrasound and RadioTHERapy for non-invasive palliative pain treatment in patients with bone metastasis: a study protocol for the three armed randomized controlled FURTHER trial

BACKGROUND

Cancer-induced bone pain (CIBP), caused by bone metastases, is a common complication of cancer and strongly impairs quality of life (QoL). External beam radiotherapy (EBRT) is the current standard of care for treatment of CIBP. However, approximately 45% of patients have no adequate pain response after EBRT. Magnetic resonance image-guided high-intensity focused ultrasound (MR-HIFU) may improve pain palliation in this patient population. The main objective of this trial was to compare MR-HIFU, EBRT, and MR-HIFU + EBRT for the palliative treatment of bone metastases.

METHODS/DESIGN

The FURTHER trial is an international multicenter, three-armed randomized controlled trial. A total of 216 patients with painful bone metastases will be randomized in a 1:1:1 ratio to receive EBRT only, MR-HIFU only, or combined treatment with EBRT followed by MR-HIFU. During a follow-up period of 6 months, patients will be contacted at eight time points to retrieve information about their level of pain, QoL, and the occurrence of (serious) adverse events. The primary outcome of the trial is pain response at 14 days after start of treatment. Secondary outcomes include pain response at 14 days after trial enrolment, pain scores (daily until the 21st day and at 4, 6, 12 and 24 weeks), toxicity, adverse events, QoL, and survival. Cost-effectiveness and cost-utility analysis will be conducted.

DISCUSSION

The FURTHER trial aims to evaluate the effectiveness and cost-effectiveness of MR-HIFU-alone or in combination with EBRT-compared to EBRT to relieve CIBP. The trial will be performed in six hospitals in four European countries, all of which are partners in the FURTHER consortium.

TRIAL REGISTRATION

The FURTHER trial is registered under the Netherlands Trials Register number NL71303.041.19 and ClinicalTrials.gov registration number NCT04307914. Date of trial registration is 13-01-2020.

Dying of Stress: Chemotherapy, Radiotherapy, and Small-Molecule Inhibitors in Immunogenic Cell Death and Immunogenic Modulation

Innovative strategies to re-establish the immune-mediated destruction of malignant cells is paramount to the success of anti-cancer therapy. Accumulating evidence suggests that radiotherapy and select chemotherapeutic drugs and small molecule inhibitors induce immunogenic cell stress on tumors that results in improved immune recognition and targeting of the malignant cells. Through immunogenic cell death, which entails the release of antigens and danger signals, and immunogenic modulation, wherein the phenotype of stressed cells is altered to become more susceptible to immune attack, radiotherapies, chemotherapies, and small-molecule inhibitors exert immune-mediated anti-tumor responses. In this review, we discuss the mechanisms of immunogenic cell death and immunogenic modulation and their relevance in the anti-tumor activity of radiotherapies, chemotherapies, and small-molecule inhibitors. Our aim is to feature the immunological aspects of conventional and targeted cancer therapies and highlight how these therapies may be compatible with emerging immunotherapy approaches.

Immune-Mediated Effects of Microplanar Radiotherapy with a Small Animal Irradiator

Spatially fractionated radiotherapy has been shown to have effects on the immune system that differ from conventional radiotherapy (CRT). We compared several aspects of the immune response to CRT relative to a model of spatially fractionated radiotherapy (RT), termed microplanar radiotherapy (MRT). MRT delivers hundreds of grays of radiation in submillimeter beams (peak), separated by non-radiated volumes (valley). We have developed a preclinical method to apply MRT by a commercial small animal irradiator. Using a B16-F10 murine melanoma model, we first evaluated the in vitro and in vivo effect of MRT, which demonstrated significant treatment superiority relative to CRT. Interestingly, we observed insignificant treatment responses when MRT was applied to Rag-/- and CD8-depleted mice. An immuno-histological analysis showed that MRT recruited cytotoxic lymphocytes (CD8), while suppressing the number of regulatory T cells (Tregs). Using RT-qPCR, we observed that, compared to CRT, MRT, up to the dose that we applied, significantly increased and did not saturate CXCL9 expression, a cytokine that plays a crucial role in the attraction of activated T cells. Finally, MRT combined with anti-CTLA-4 ablated the tumor in half of the cases, and induced prolonged systemic antitumor immunity.

Atezolizumab-bevacizumab plus Y-90 TARE for the treatment of hepatocellular carcinoma: preclinical rationale and ongoing clinical trials

INTRODUCTION

The treatment algorithm of advanced hepatocellular carcinoma (HCC) has evolved since the introduction of immunotherapy. The IMbrave150 trial set atezolizumab-bevacizumab as a new standard-of-care first-line treatment for unresectable HCC patients. However, for patients with intermediate or advanced stage with portal vein thrombosis but without distant metastases, ⁹⁰Yttrium transarterial radioembolization (⁹⁰Y-TARE) is considered the treatment of choice.

AREAS COVERED

We discuss the main evidence regarding the use of ⁹⁰Y-TARE in HCC, the recent progress of immunotherapy in this tumor, and the preclinical rationale of combining VEGF blockade with the other two treatment strategies.

EXPERT OPINION

HCC has an extremely heterogeneous tumor immune microenvironment. This may explain the inconsistent outcomes obtained with immune-checkpoint inhibitors. The identification of patients who could benefit most from immunotherapy is crucial; however, reliable markers of response are lacking. Radiation therapy and VEGF inhibition have an established synergism with immunotherapy, mainly linked to enhanced antigen presentation and reduced immunosuppressive immune infiltrate. Combining an immune-checkpoint inhibitor with VEGF blockade and ⁹⁰Y-TARE might hence overcome primary resistances observed when each of these treatments is administerd alone.

Improving cancer treatments via dynamical biophysical models

Despite significant advances in oncological research, cancer nowadays remains one of the main causes of mortality and morbidity worldwide. New treatment techniques, as a rule, have limited efficacy, target only a narrow range of oncological diseases, and have limited availability to the general public due their high cost. An important goal in oncology is thus the modification of the types of antitumor therapy and their combinations, that are already introduced into clinical practice, with the goal of increasing the overall treatment efficacy. One option to achieve this goal is optimization of the schedules of drugs administration or performing other medical actions. Several factors complicate such tasks: the adverse effects of treatments on healthy cell populations, which must be kept tolerable; the emergence of drug resistance due to the intrinsic plasticity of heterogeneous cancer cell populations; the interplay between different types of therapies administered simultaneously. Mathematical modeling, in which a tumor and its microenvironment are considered as a single complex system, can address this complexity and can indicate potentially effective protocols, that would require experimental verification. In this review, we consider classical methods, current trends and future prospects in the field of mathematical modeling of tumor growth and treatment. In particular, methods of treatment optimization are discussed with several examples of specific problems related to different types of treatment.

Lumpectomy followed by radiation improves survival in HER2 positive and triple-negative breast cancer with high tumor-infiltrating lymphocytes compared to mastectomy alone

OBJECTIVE

The goal was to compare the 5-year DFS and 5-year OS in patients with early-stage human epidermal growth factor receptor 2 breast cancer (HER2+ BC) and triple-negative breast cancer (TNBC) in relation to the amount of stromal tumor-infiltrating lymphocytes (TILs) after locoregional management by either mastectomy without radiation or lumpectomy and whole-breast radiotherapy (RT).

METHODS

This was a retrospective review of HER2+ BC and TNBC patients' charts and histopathology slides with clinical stage of T1-T2 N0 who presented at our facility between January 2009 and December 2019. Locoregional treatment included either mastectomy without RT (M) or lumpectomy with RT (L+R). TILs were assessed by three pathologists using the guidelines of the 2014 TILs working group. A competing risk model and Kaplan-Meier analysis were used to analyze correlations between TILs levels and clinical outcome.

RESULTS

We reviewed 211 patients' charts. Of them, 190 proceeded to the final analysis. Patients were split into groups of "low TILs" and "high TILs" based on a 50% TILs cut-off. Of them 26% had high TILs, 48% received RT, 97% received chemotherapy, all HER2+ BC patients received HER2-directed therapy and all HER2+ BC that were also hormone receptor positive (HR+) received endocrine therapy (ET). In patient with low TILs, L+R did not improve outcomes compared to M. Moreover, patients with high TILs had a significant improvement of their DFS and OS with L+R when compared to M.

CONCLUSION

The results of our study reflect that a selected group of HER2+ BC and TNBC with elevated TILs, L+R is associated with improvement of 5-year DFS and 5-year OS.

Nivolumab and Hypofractionated Radiotherapy in Patients With Advanced Lung Cancer: ABSCOPAL-1 Clinical Trial

Background

More clinical practice need to be performed to verify the toxicity of the hypofractionated radiotherapy (HFRT) combined with PD-1 blockade in lung cancer. This phase I study aimed to investigate the safety and efficacy of nivolumab combined with HFRT in patients with progressive advanced lung cancer following multiline treatment.

Methods

We enrolled 31 patients with advanced lung cancer pathologically confirmed to have progressive disease and treated with first-line or a higher therapy. Selected lesions were treated using HFRT, and nivolumab was administered within 7 days subsequently. Nivolumab was administered once a month following partial remission. Peripheral blood was collected before and after 1 month of treatment to evaluate relevant cytokines between nivolumab responders and non-responders.

Results

Overall, 23 patients who completed the treatment were evaluated. Of them, 9 and 14 patients underwent hypofractionated brachytherapy with 30 Gy in a single fraction via percutaneous interstitial implantation of (192)Ir and 40-50 Gy in 5 fractions via stereotactic body radiation therapy, respectively. The median follow-up period was 11 months. At the 1-year follow-up, no patient developed grade ≥ 3 pneumonitis. The overall objective response and complete remission rates were 39.13% and 13.04%, respectively. The 1-year overall survival and median progression-free survival were 60.9% and 6 months, respectively. The plasma levels of interleukin IL-6, IL-10, and IL-17A were significantly reduced after treatment in nivolumab responders.

Conclusions

HFRT could increase the responsivity to nivolumab and reduce its administration frequency. This combination treatment is well tolerated with acceptable toxicity and thus merits further trials to validate benefits.

Clinical Trial Registration

http://www.chictr.org.cn/index.aspx, identifier ChiCTR-1900027768.

Temporal analysis of type 1 interferon activation in tumor cells following external beam radiotherapy or targeted radionuclide therapy

Rationale: Clinical interest in combining targeted radionuclide therapies (TRT) with immunotherapies is growing. External beam radiation therapy (EBRT) activates a type 1 interferon (IFN1) response mediated via stimulator of interferon genes (STING), and this is critical to its therapeutic interaction with immune checkpoint blockade. However, little is known about the time course of IFN1 activation after EBRT or whether this may be induced by decay of a TRT source. Methods: We examined the IFN1 response and expression of immune susceptibility markers in B78 and B16 melanomas and MOC2 head and neck cancer murine models using qPCR and western blot. For TRT, we used 90Y chelated to NM600, an alkylphosphocholine analog that exhibits selective uptake and retention in tumor cells including B78 and MOC2. Results: We observed significant IFN1 activation in all cell lines, with peak activation in B78, B16, and MOC2 cell lines occurring 7, 7, and 1 days, respectively, following RT for all doses. This effect was STING-dependent. Select IFN response genes remained upregulated at 14 days following RT. IFN1 activation following STING agonist treatment in vitro was identical to RT suggesting time course differences between cell lines were mediated by STING pathway kinetics and not DNA damage susceptibility. In vivo delivery of EBRT and TRT to B78 and MOC2 tumors resulted in a comparable time course and magnitude of IFN1 activation. In the MOC2 model, the combination of 90Y-NM600 and dual checkpoint blockade therapy reduced tumor growth and prolonged survival compared to single agent therapy and cumulative dose equivalent combination EBRT and dual checkpoint blockade therapy. Conclusions: We report the time course of the STING-dependent IFN1 response following radiation in multiple murine tumor models. We show the potential of TRT to stimulate IFN1 activation that is comparable to that observed with EBRT and this may be critical to the therapeutic integration of TRT with immunotherapies.

Risk and impact of radiation related lymphopenia in lung cancer: A systematic review and meta-analysis

BACKGROUND

Despite the modern advances in treatment techniques, the survival of locally advanced lung cancer patients continues to remain poor. Circulating lymphocytes have an important role to play in local immune response to RT as well as immune checkpoint inhibitors, and radiation related lymphopenia has been associated with inferior survival in various tumors.

METHODS

We undertook this systematic review and meta-analysis to evaluate the literature on risk and impact of lymphopenia in thoracic tumors. A systematic methodology search of the PubMed, Embase and Cochrane library was performed and eligible studies selected based on pre-defined inclusion and exclusion criteria. Review Manager Version 5.4.1 was used for the meta-analysis.

RESULTS

Fourteen studies were included in the final systematic review and 10 in the quantitative analysis. Overall mean incidence of severe lymphopenia (absolute lymphocyte count < 500) was 64.24%. The patients with severe lymphopenia were at increased risk of death with a pooled HR of 1.59 (95% CI: 1.40, 1.81, I² = 17%, P < 0.001) and progression with a pooled HR of 2.1 (95% CI: 1.57, 2.81, I² = 59%, P < 0.001) compared to patients with no severe lymphopenia. Dosimetric parameters including gross tumor volume, lung V5 and heart V5 were predictive of lymphopenia, while advanced age, lower baseline lymphocyte counts, higher stage and large tumor size were other risk factors. Models predicting estimated radiation dose to lymphocytes were a good surrogate for treatment outcomes.

CONCLUSION

Radiation related lymphopenia is associated with increased hazard of progression and death in lung cancer. Minimizing the lung and heart dose, especially in patients with concurrent other risk factors can reduce lymphopenia and potentially improve treatment outcomes in these patients.

Combining radiotherapy and focused ultrasound for pain palliation of cancer induced bone pain; a stage I/IIa study according to the IDEAL framework

•

Combined treatment of EBRT and MR-HIFU is feasible and well tolerated by patients.

•

Clinical outcomes of combined treatment of EBRT and MR-HIFU are promising.

•

Superiority of combined treatment over standard EBRT needs to be evaluated in a comparative study.

Background

Cancer induced bone pain (CIBP) strongly interferes with patient’s quality of life. Currently, the standard of care includes external beam radiotherapy (EBRT), resulting in pain relief in approximately 60% of patients. Magnetic Resonance guided High Intensity Focused Ultrasound (MR-HIFU) is a promising treatment modality for CIBP.

Methods

A single arm, R-IDEAL stage I/IIa study was conducted. Patients presenting at the department of radiation oncology with symptomatic bone metastases in the appendicular skeleton, as well as in the sacrum and sternum were eligible for inclusion. All participants underwent EBRT, followed by MR-HIFU within 4 days. Safety and feasibility were assessed, and pain scores were monitored for 4 weeks after completing the combined treatment.

Results

Six patients were enrolled. Median age was 67 years, median lesion diameter was 56,5 mm. In all patients it was logistically possible to plan and perform the MR-HIFU treatment within 4 days after EBRT. All patients tolerated the combined procedure well. Pain response was reported by 5 out of 6 patients at 7 days after completion of the combined treatment, and stabilized on 60% at 4 weeks follow up. No treatment related serious adverse events occurred.

Conclusion

This is the first study to combine EBRT with MR-HIFU. Our results show that combined EBRT and MR-HIFU in first-line treatment of CIBP is safe and feasible, and is well tolerated by patients. Superiority over standard EBRT, in terms of (time to) pain relief and quality of life need to be evaluated in comparative (randomized) study.

Advances in Hypofractionated Irradiation-Induced Immunosuppression of Tumor Microenvironment

Hypofractionated radiotherapy is external beam irradiation delivered at higher doses in fewer fractions than conventional standard radiotherapy, which can stimulate innate and adaptive immunity to enhance the body’s immune response against cancer. The enhancement effect of hypofractionated irradiation to immune response has been widely investigated, which is considered an approach to expand the benefit of immunotherapy. Meanwhile, increasing evidence suggests that hypofractionated irradiation may induce or enhance the suppression of immune microenvironments. However, the suppressive effects of hypofractionated irradiation on immunomicroenvironment and the molecular mechanisms involved in these conditions are largely unknown. In this context, we summarized the immune mechanisms associated with hypofractionated irradiation, highlighted the advances in its immunosuppressive effect, and further discussed the potential mechanism behind this effect. In our opinion, besides its immunogenic activity, hypofractionated irradiation also triggers homeostatic immunosuppressive mechanisms that may counterbalance antitumor effects. And this may suggest that a combination with immunotherapy could possibly improve the curative potential of hypofractionated radiotherapy.

Immune Infiltrate in the Primary Tumor Predicts Effect of Adjuvant Radiotherapy in Breast Cancer; Results from the Randomized SweBCG91RT Trial

PURPOSE

Tumor-infiltrating immune cells play a key role in tumor progression. The purpose of this study was to analyze whether the immune infiltrate predicts benefit from postoperative radiotherapy in a large randomized breast cancer radiotherapy trial.

EXPERIMENTAL DESIGN

In the SweBCG91RT trial, patients with stage I and II breast cancer were randomized to breast-conserving surgery (BCS) and postoperative radiotherapy or to BCS only and followed for a median time of 15.2 years. The primary tumor immune infiltrate was quantified through two independent methods: IHC and gene expression profiling. For IHC analyses, the absolute stromal area occupied by CD8⁺ T cells and FOXP3⁺ T cells, respectively, was used to define the immune infiltrate. For gene expression analyses, immune cells found to be prognostic in independent datasets were pooled into two groups consisting of antitumoral and protumoral immune cells, respectively.

RESULTS

An antitumoral immune response in the primary tumor was associated with a reduced risk of breast cancer recurrence and predicted less benefit from adjuvant radiotherapy. The interaction between radiotherapy and immune phenotype was significant for any recurrence in both the IHC and gene expression analyses (P = 0.039 and P = 0.035) and was also significant for ipsilateral breast tumor recurrence in the gene expression analyses (P = 0.025).

CONCLUSIONS

Patients with an antitumoral immune infiltrate in the primary tumor have a reduced risk of any recurrence and may derive less benefit from adjuvant radiotherapy. These results may impact decisions regarding postoperative radiotherapy in early breast cancer.

Effective combinations of radiotherapy and immunotherapy in the treatment of esophageal squamous cell carcinoma

The traditional treatments for esophageal squamous cell carcinoma include surgery and radiation as local therapies, then chemotherapy and targeted therapy as systemic treatments. These treatments, either alone or in combination, however, are not satisfactory because of limited efficacy and unfavorable toxicity, calling for new therapeutic strategies. In recent years, immunotherapy, a new weapon in the arsenal against cancer, has shown substantial clinical benefits in patients with esophageal squamous cell carcinoma, particularly ones with locally advanced or metastatic disease. Importantly, accumulating evidence suggests that traditional radiation therapy functions as a powerful adjuvant for immunotherapy by contributing to systemic antitumor immunity, resulting in reduced recurrence risk and improved survival of patients. Here the authors summarize the emerging data on immunotherapy- and radiation therapy-based treatment of esophageal squamous cell carcinoma and discuss the pros and cons of different combinations, aiming at a comprehensive understanding of the proper rationale for the design of effective therapeutic regimens.

Modern evidence and future prospects of external body radiation therapy for lung oligometastases of breast cancer

After Hellman and Weichselbaum defined "Oligometastasis" in 1995, several local therapies for lung oligometastases including surgical resection and external body radiation therapy were reported that improved local control (LC) and progression-free survival, overall survival, and quality of life. This suggests that oligometastases is a potentially curable state. Modern advances in radiation therapy such as stereotactic body radiation therapy (SBRT) in which high dose coverage of target lesion without exposure of normal organ is possible, and are widely used to treat solitary or a limited number of primary lung cancer and metastases. Several reports showed that SBRT was a useful treatment method for lung oligometastases, and the LC rate of SBRT was 80-90% in 2 years and less invasive than surgical resection. SBRT is a safe and effective especially for small and peripheral lung metastases. However, if the metastatic lesion is big or centrally located, careful treatment is necessary to prevent radiation pneumonitis. After SBRT, it is sometimes difficult to differentiate local recurrence and pulmonary injury, especially in the early phase. However, it is important to detect local recurrence especially in patients who require further local therapy such as surgical resection and re-irradiation or systemic therapy. The diagnosis can be improved by determining the natural course after SBRT and local recurrence with computed tomography imaging and ¹⁸F-fluorodeoxyglucose positron emission tomography, respectively. Moreover, radiation therapy may have both local and systemic effects that are related to the enhancement of immune-response after radiation. Currently, several trials evaluating the benefits of SBRT for oligometastatic breast cancer are underway. However, the adaption of SBRT for lung metastases including other treatment strategies should be carefully discussed by the radiation oncologist and a multi-disciplinary team comprising a breast surgeon, medical oncologist, diagnostic radiologist, and radiation oncologist, among others.

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.

Systemic modulation of stress and immune parameters in patients treated for prostate adenocarcinoma by intensity-modulated radiation therapy or stereotactic ablative body radiotherapy

Background

In this exploratory study, the impact of local irradiation on systemic changes in stress and immune parameters was investigated in eight patients treated with intensity-modulated radiation therapy (IMRT) or stereotactic ablative body radiotherapy (SABR) for prostate adenocarcinoma to gain deeper insights into how radiotherapy (RT) modulates the immune system.

Patients and methods

RT-qPCR, flow cytometry, metabolomics, and antibody arrays were used to monitor a panel of stress- and immune-related parameters before RT, after the first fraction (SABR) or the first week of treatment (IMRT), after the last fraction, and 3 weeks later in the blood of IMRT (N = 4) or SABR (N = 4) patients. Effect size analysis was used for comparison of results at different timepoints.

Results

Several parameters were found to be differentially modulated in IMRT and SABR patients: the expression of TGFB1, IL1B, and CCL3 genes; the expression of HLA-DR on circulating monocytes; the abundance and ratio of phosphatidylcholine and lysophosphatidylcholine metabolites in plasma. More immune modulators in plasma were modulated during IMRT than SABR, with only two common proteins, namely GDF-15 and Tim‑3.

Conclusion

Locally delivered RT induces systemic modulation of the immune system in prostate adenocarcinoma patients. IMRT and SABR appear to specifically affect distinct immune components.

Electronic supplementary material

The online version of this article (10.1007/s00066-020-01637-5) contains supplementary material, which is available to authorized users.

Increased effect of two-fraction radiotherapy in conjunction with IDO1 inhibition in experimental glioblastoma

Objectives

The aim of the study was to investigate therapeutic efficacy of single- or two-fraction radiotherapy in conjunction with IDO1-inhibition in a syngeneic rat glioblastoma model. IDO is known to cause immunosuppression through breakdown of tryptophan in the tumor microenvironment.

Methods

Gene expression analyses of IDO in glioblastoma were performed with data from publicly available datasets. Fractionation studies were done on animals to evaluate tumor size, immune cell infiltration of tumors and serum profile on day 18 after tumor inoculation. Survival analyses were done with animals carrying intracranial glioblastomas comparing two-fraction radiotherapy+IDO1-inhibition to controls. IDO inhibition was achieved by administration of 1-methyl tryptophan (1-MT), and radiotherapy (RT) was delivered in doses of 8Gy.

Results

The expression of IDO1 was increased on gene level in glioblastoma stem cells. Tumor size was significantly reduced in animals treated with 1-MT+RTx 2 (both long and short intervals, i.e. 7 and 4 days between the treatments) as compared to control animals, animals treated with only 1-MT or animals treated with 1-MT+RTx1. Serum levels of IL-1A were significantly altered in all treated animals as compared to control animals. Survival was significantly increased in the animals treated with 1-MT+RTx2 (7-day interval) compared to control animals.

Conclusions

Addition of two-fraction RT to IDO1 inhibition with 1-MT significantly reduced tumor size in animals with glioblastoma. Survival was significantly increased in animals treated with two-fractioned RT+1-MT as compared to untreated controls increased significantly.

Advances in knowledge

The currently used combination of only two fractions of radiotherapy and immune therapy is a promising area of research, increasing efficacy compared to single fraction irradiation, while potentially lowering radiation side effects compared to radiation in current clinical practice.

Abscopal effect of local irradiation treatment for thymoma: a case report

INTRODUCTION

With the rapid development of immunotherapy in recent years, growing clinical evidence suggests that a combination of radiotherapy and immunotherapy could improve the abscopal response rates and increase survival. However, observations on abscopal effects in patients receiving radiotherapy alone are still very rare. This study reports a rare case of a patient with type B3 thymoma with multiple lung metastases, who received localized irradiation.

CASE PRESENTATION

A 76-year-old Chinese woman was admitted to our hospital in November 2017, and her physical examination revealed a thymus mass with multiple lung metastases. Although the left lower lobe lesion was slightly larger than before, the patient presented with regression of the non-irradiated metastases after treatment with radiotherapy alone.

CONCLUSION

This patient experienced an apparent regression of metastatic mass, suggesting a radiation-induced abscopal effect.

Intraoperative Strahlentherapie – Indikationen und Optionen in der Viszeralchirurgie

Hintergrund

Die intraoperative Strahlentherapie (IORT) ermöglicht durch die chirurgische Exposition des Tumors und des Tumorbetts eine hohe Präzision, welche eine hohe Strahlendosis im Bereich des Tumors zulässt und gleichzeitig gesundes Gewebe als den dosislimitierenden Faktor vor Strahlung schützt. Aus diesem Grund bietet die IORT besonders dann einen Vorteil, wenn die lokale Tumorkontrolle das Langzeitüberleben entscheidend beeinflusst und Funktionserhalt ermöglicht.

Ziel der Arbeit

Die in dieser Übersichtsarbeit aufgearbeiteten Erkenntnisse aus der Literaturrecherche erlauben einen evidenzbasierten Umgang hinsichtlich Indikationen und Therapieoptionen der IORT für intraabdominelle Tumoren.

Ergebnisse und Schlussfolgerung

Die Effektivität der IORT kann anhand der vorhandenen Evidenzlage nicht abschließend beurteilt werden, jedoch ist die IORT als Ergänzung der multimodalen Therapie bei (Rezidiv‑)Rektumkarzinomen und Sarkomen aktiv im klinischen Alltag etabliert. Magen- und Pankreaskarzinome stellen weitere Indikationen dar; ergänzende Studien sind jedoch notwendig, um die Rolle der IORT hier klar zu definieren. Ein wesentlicher Faktor, damit für Patienten mit primärem Karzinom und insbesondere für Patienten mit lokalem Rezidiv verbesserte lokale Rezidiv- und Überlebensraten erreicht werden können, scheint die Patientenselektion zu sein.

Blood and tissue biomarker analysis in dogs with osteosarcoma treated with palliative radiation and intra-tumoral autologous natural killer cell transfer

We have previously reported radiation-induced sensitization of canine osteosarcoma (OSA) to natural killer (NK) therapy, including results from a first-in-dog clinical trial. Here, we report correlative analyses of blood and tissue specimens for signals of immune activation in trial subjects. Among 10 dogs treated with palliative radiotherapy (RT) and intra-tumoral adoptive NK transfer, we performed ELISA on serum cytokines, flow cytometry for immune phenotype of PBMCs, and PCR on tumor tissue for immune-related gene expression. We then queried The Cancer Genome Atlas (TCGA) to evaluate the association of cytotoxic/immune-related gene expression with human sarcoma survival. Updated survival analysis revealed five 6-month survivors, including one dog who lived 17.9 months. Using feeder line co-culture for NK expansion, we observed maximal activation of dog NK cells on day 17-19 post isolation with near 100% expression of granzyme B and NKp46 and high cytotoxic function in the injected NK product. Among dogs on trial, we observed a trend for higher baseline serum IL-6 to predict worse lung metastasis-free and overall survival (P = 0.08). PCR analysis revealed low absolute gene expression of CD3, CD8, and NKG2D in untreated OSA. Among treated dogs, there was marked heterogeneity in the expression of immune-related genes pre- and post-treatment, but increases in CD3 and CD8 gene expression were higher among dogs that lived > 6 months compared to those who did not. Analysis of the TCGA confirmed significant differences in survival among human sarcoma patients with high and low expression of genes associated with greater immune activation and cytotoxicity (CD3e, CD8a, IFN-γ, perforin, and CD122/IL-2 receptor beta). Updated results from a first-in-dog clinical trial of palliative RT and autologous NK cell immunotherapy for OSA illustrate the translational relevance of companion dogs for novel cancer therapies. Similar to human studies, analyses of immune markers from canine serum, PBMCs, and tumor tissue are feasible and provide insight into potential biomarkers of response and resistance.

Radiation therapy and immunotherapy: what is the optimal timing or sequencing?

Radiotherapy is a component of the standard of care for many patients with locally advanced nonmetastatic tumors and increasingly those with oligometastatic tumors. Despite encouraging advances in local control and progression-free and overall survival outcomes, continued manifestation of tumor progression or recurrence leaves room for improvement in therapeutic efficacy. Novel combinations of radiation with immunotherapy have shown promise in improving outcomes and reducing recurrences by overcoming tumor immune tolerance and evasion mechanisms via boosting the immune system's ability to recognize and eradicate tumor cells. In this review, we discuss preclinical and early clinical evidence that radiotherapy and immunotherapy can improve treatment outcomes for locally advanced and metastatic tumors, elucidate underlying molecular mechanisms and address strategies to optimize timing and sequencing of combination therapy for maximal synergy.

Effect of Radiotherapy After Breast-Conserving Surgery Depending on the Presence of Tumor-Infiltrating Lymphocytes: A Long-Term Follow-Up of the SweBCG91RT Randomized Trial

PURPOSE

The effects of radiotherapy (RT) on the basis of the presence of stromal tumor infiltrating lymphocytes (TILs) have not been studied. The purpose of this study was to analyze the association of TILs with the effect of postoperative RT on ipsilateral breast tumor recurrence (IBTR) in a large randomized trial.

METHODS

In the SweBCT91RT (Swedish Breast Cancer Group 91 Radiotherapy) trial, 1,178 patients with breast cancer stage I and II were randomly assigned to breast-conserving surgery plus postoperative RT or breast-conserving surgery only and followed for a median of 15.2 years. Tumor blocks were retrieved from 1,003 patients. Stromal TILs were assessed on whole-section hematoxylin-eosin–stained slides using a dichotomized cutoff of 10%. Subtypes were scored using immunohistochemistry on tissue microarray. In total, 936 patients were evaluated.

RESULTS

Altogether, 670 (71%) of patients had TILs less than 10%. In a multivariable regression analysis with IBTR as dependent variable and RT, TILs, subtype, age, and grade as independent variables, RT (hazard ratio [HR], 0.42; 95% CI, 0.29 to 0.61; P < .001), high TILs (HR, 0.61; 95% CI, 0.39 to 0.96, P = .033) grade (3 v 1; HR, 2.17; 95% CI, 1.08 to 4.34; P = .029), and age (≥ 50 v < 50 years; HR, 0.55; 95% CI, 0.38 to 0.80; P = .002) were predictive of IBTR. RT was significantly beneficial in the low TILs group (HR, 0.37; 95% CI, 0.24 to 0.58; P < .001) but not in the high TILs group (HR, 0.58; 95% CI, 0.28 to 1.19; P = .138). The test for interaction between RT and TILs was not statistically significant ( P = .317).

CONCLUSION

This study shows that high values of TILs in the primary tumor independently seem to reduce the risk for an IBTR. Our findings further suggest that patients with breast cancer with low TILs may derive a larger benefit from RT regarding the risk of IBTR.

A Current Review of Spatial Fractionation: Back to the Future?

Spatially fractionated radiation therapy represents a significant departure from canonical thinking in radiation oncology despite having origins in the early 1900s. The original and most common implementation of spatially fractionated radiation therapy uses commercially available blocks or multileaf collimators to deliver a nonconfluent, sieve-like pattern of radiation to the target volume in a nonuniform dose distribution. Dosimetrically, this is parameterized by the ratio of the valley dose in cold spots to the peak dose in hot spots, or the valley-to-peak dose ratio. The radiobiologic mechanisms are postulated to involve radiation-induced bystander effects, microvascular alterations, and/or immunomodulation. Current indications include bulky or locally advanced disease that would not be amenable to conventional radiation or that has proved refractory to chemoradiation. Early-phase clinical trials have shown remarkable success, with some response rates >90% and minimal toxicity. This has promoted technological developments in 3-dimensional formats (LATTICE), micron-size beams (microbeam), and proton arrays. Nevertheless, more clinical and biological data are needed to specify ideal dosimetry parameters and to formulate robust clinical indications and guidelines for optimal standardized care.

Template-assisted 192Ir-based stereotactic ablative brachytherapy as a neoadjuvant treatment for operable peripheral non-small cell lung cancer: a phase I clinical trial

Purpose

To evaluate safety, feasibility, and efficacy of template-assisted ¹⁹²Ir-based stereotactic ablative brachytherapy (SABT), combined with surgery for peripheral non-small cell lung cancer (NSCLC).

Material and methods

Patients with pathologically confirmed operable peripheral NSCLC, who underwent template-assisted SABT (30 Gy delivered in one fraction) and were scheduled for tumor resection 4-6 weeks after SABT were included in this study. The perioperative adverse reactions of SABT were recorded to evaluate safety and feasibility of SABT for neoadjuvant therapy. Dosimetric data from both simulated and actual plans were collected and compared. Imaging with ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) and dynamic contrast-enhanced computed tomography were scheduled before SABT and surgery to evaluate the efficacy of the neoadjuvant therapy with SABT.

Results

Patients did not experience any serious adverse events. None of the patients had a delay in receiving surgery. After 4-6 weeks, the indicators for the efficacy of neoadjuvant therapy significantly decreased in all patients: gross tumor volume (p < 0.001), maximum standardized uptake value (p < 0.001), tumor blood volume (p < 0.001), and tumor blood flow (p = 0.008). Dosimetric parameters in the delivered SABT plan slightly changed from the preoperative simulation, but the difference was not statistically significant (p > 0.05).

Conclusions

The efficacy of template-assisted SABT for neoadjuvant therapy was significant in operable peripheral NSCLC. Moreover, no serious adverse reactions were observed; when the coplanar template guidance technique was applied, dosimetric parameters were in good agreement between the actual SABT plan and the preoperative simulated plan.

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 failure of radical treatments to cure cancer: can less deliver more?

All too often attempts to deliver improved cancer cure rates by increasing the dose of a particular treatment are not successful enough to justify the accompanying increase in toxicity and reduction in quality of life suffered by a significant number of patients. In part, this drive for using higher levels of treatment derives from the nature of the process for testing and incorporation of new protocols. Indeed, new treatment regimens must now consider the key role of immunity in cancer control, a component that has been largely ignored until very recently. The recognition that some drugs developed for cytotoxicity at higher doses can display alternative anticancer activities at lower doses including through modulation of immune responses is prompting a significant re-evaluation of treatment protocol development. Given that tumours are remarkably heterogeneous and with inherent genetic instability it is probably only the adaptive immune response with its flexibility and extensive repertoire that can rise to the challenge of effecting significant control and ultimately elimination of a patient's cancer. This article discusses some of the elements that have limited higher levels of treatment outcomes and where too much proved less effective. We explore observations that less can often be as effective, if not more effective especially with some chemotherapy regimens, and discuss how this can be exploited in combination with immunotherapies to deliver nontoxic improved tumour responses.

Abscopal effect following radiation monotherapy in breast cancer: A case report

Radiotherapy has been found to be valuable for the control and eradication of local foci in various malignant tumors. The abscopal effect is determined as a systemic antitumor response at a distance from the irradiation site invoked by local irradiation. We herein present an extremely rare case of breast cancer in a 64-year-old woman, in whom the abscopal effect was observed after radiotherapy induced an antitumor response in all metastatic lesions, without any combination therapy. The patient was admitted to our hospital complaining of a breast mass and pain at the left hip, and was diagnosed with breast cancer with multiple bone, lung and lymph node metastases. She received treatment with local radiotherapy delivered to the breast tumor and some of the bone metastases but did not receive chemotherapy due to her poor performance status. However, 10 months after radiotherapy, spontaneous regression was observed, not only within the irradiated field, but also in the non-irradiated areas. All signs of cancer throughout the body disappeared, and the patient's performance status drastically improved. To the best of our knowledge, there have been no reports of advanced breast cancer cases in which the abscopal effect was observed after radiation monotherapy; therefore, this case report is extremely rare and highly valuable.

Exploring the rationale for combining ionizing radiation and immune checkpoint blockade in head and neck cancer

BACKGROUND

The ability of radiation to enhance antitumor immunity under specific experimental conditions is well established. Here, we explore preclinical data and the rationale for combining different radiation doses and fractions with immune checkpoint blockade immunotherapy.

METHODS

We conducted a review of the literature.

RESULTS

The ability of high-dose or hypofractionated radiation to enhance antitumor immunity resulting in additive or synergistic tumor control when combined with checkpoint blockade is well studied. Whether low-dose daily fractionated radiation does the same is less well studied and available data suggests it may be immunosuppressive.

CONCLUSION

Although daily fractionated radiation is well established as the standard of care for the treatment of patients with head and neck cancer, how this radiation schema alters antitumor immunity needs further study. If the radiation doses and fractions alter antitumor immunity differently can have profound implications in the rational design of clinical trials investigating whether radiation can enhance response rates to immune checkpoint blockade.

Safety and efficacy of concurrent immune checkpoint inhibitors and hypofractionated body radiotherapy

Integration of hypofractionated body radiotherapy (H-RT) into immune checkpoint inhibitor (ICI) therapy may be a promising strategy to improve the outcomes of ICIs, although sufficient data is lacking regarding the safety and efficacy of this regimen. We, hereby, reviewed the safety and efficacy of this combination in 59 patients treated with H-RT during or within 8 weeks of ICI infusion and compared results with historical reports of ICI treatment alone. Most patients had RCC or melanoma. Median follow-up was 11 months. Most patients received either Nivolumab alone or with Ipilimumab; 83% received stereotactic RT and 17% received conformal H-RT. Any grade adverse events (AEs) were reported in 46 patients, and grade 3-4 in 12 patients without any treatment-related grade 5 toxicity. The most common grade 3 AEs were fatigue and pneumonitis. Grade 3-4 toxicities were higher with ICI combination and with simultaneous ICIs. Overall, most any-grade or grade ≥3 AE rates did not differ significantly from historically reported rates with single-agent or multi-agent ICIs. Toxicity did not correlate with H-RT site, dose, fraction number, tumor type, or ICI and H-RT sequencing. Median progression-free survival was 6.5 months. Objective response rate (ORR) was 26%; 10% had complete response (CR). Median duration of response was 9.4 ± 4.6 months. H-RT of lung lesions was more likely to achieve CR than other sites. H-RT of bone lesions had a lower ORR than non-bone H-RT. In conclusion, combining body H-RT with ICIs is safe and promising. Prospective validation is warranted.

Comparative analysis of the effect of different radiotherapy regimes on lymphocyte and its subpopulations in breast cancer patients

PURPOSE

The aim of this study was to determine whether different radiotherapy (RT) fractionation schemes induce disparate effects on lymphocyte and its subsets in breast cancer patients.

METHODS

60 female patients diagnosed with breast cancer were recruited in this study after receiving modified radical mastectomy and were randomly divided into two groups. One group received irradiation at a standard dose of 50 Gy in 25 fractions and the other at a dose of 40.3 Gy in 13 fractions. Both total lymphocyte count and its composition were recorded at three timepoints: right before the radiation treatment (T0), immediately after the last fraction of radiotherapy (T1) and 6 months after irradiation therapy ended (T2).

RESULTS

Both groups experienced temporal lymphopenia after finishing local radiation (T1) (13F T0 vs. T1 1570.6 ± 243.9 vs. 940.6 ± 141.8, **p < 0.01; 25F T0 vs. T1 1620.5 ± 280.2 vs. 948.5 ± 274.6, **p < 0.01), while the lymphocyte count recovered at follow-up time (T2), and the cell count in the hypofractionation group (13F) was higher than the standard fraction group (25F) (13F vs. 25F 1725.6 ± 225.6 vs. 1657.5 ± 242.4, *p < 0.05). With respect to the composition of lymphocyte, we found T cell, B cell, and NK cell reacted differently to different radiotherapy protocols.

CONCLUSIONS

Different RT protocols impose different impacts on immunity, leading us to further explore the optimal radiotherapy regimes to synergy with immunotherapy.

Incorporating Radiation Oncology into Immunotherapy: proceedings from the ASTRO-SITC-NCI immunotherapy workshop

Radiotherapy (RT) has been a fundamental component of the anti-cancer armamentarium for over a century. Approximately half of all cancer patients are treated with radiotherapy during their disease course. Over the two past decades, there has been a growing body of preclinical evidence supporting the immunomodulatory effects of radiotherapy, particularly when combined with immunotherapy, but only anecdotal clinical examples existed until recently. The renaissance of immunotherapy and the recent U.S. Food and Drug Administration (FDA) approval of several immune checkpoint inhibitors (ICIs) and other immuno-oncology (IO) agents in multiple cancers provides the opportunity to investigate how localized radiotherapy can induce systemic immune responses. Early clinical experiences have demonstrated feasibility of this approach but additional preclinical and clinical investigation is needed to understand how RT and immunotherapy can be optimally combined.

To address questions that are critical to successful incorporation of radiation oncology into immunotherapy, the American Society for Radiation Oncology (ASTRO), the Society for Immunotherapy of Cancer (SITC) and the National Cancer Institute (NCI) organized a collaborative scientific workshop, Incorporating Radiation Oncology into Immunotherapy, that convened on June 15 and 16 of 2017 at the Natcher Building, NIH Campus in Bethesda, Maryland. This report summarizes key data and highlights from each session.

Immune Analysis of Radium-223 in Patients With Metastatic Prostate Cancer

BACKGROUND

Radium223 (Ra223) delivers high-energy radiation to osteoblastic metastasis of prostate cancer, resulting in irreparable double-stranded DNA damage. The effects of Ra223 on CD8+ T cell subsets in patients with prostate cancer is unknown.

PATIENTS AND METHODS

Fifteen men with metastatic prostate cancer with clinical indication for Ra223 without any autoimmune or immune deficiency conditions were enrolled. Patients received a course of Ra223 50 kBq/kg. Concurrent use of prednisone ≤ 10 mg a day was allowed. Peripheral blood samples were collected before and 3 to 4 weeks after the first dose of Ra223 50 kBq/kg. Peripheral blood mononuclear cells were purified and analyzed for the phenotypic and functional characteristics of CD8⁺ T cells using flow cytometry.

RESULTS

One Ra223 treatment did not result in significant change in the overall frequencies of CD8⁺ T cells and their subsets including naive, central memory, and effect memory cells. However, the mean frequency of programmed cell death protein 1-expressing EM CD8⁺ T cells decreased after 1 Ra223 treatment from 20.6% to 14.6% (P = .020), whereas no significant change was observed in the frequencies of CD27-, CD28-, or CTLA4-expressing T cells. One Ra223 treatment was not associated with any significant change in the frequencies of CD8⁺ T cells producing IFN-γ, TNF-α, and IL-13.

CONCLUSION

One Ra223 treatment is associated with a decreased mean frequency of programmed cell death protein 1-expressing effect memory CD8⁺ T cell without affecting other immune checkpoint molecules or cytokine production. Further investigations are warranted to elucidate the immunologic and clinical significance of our observations and its long-term effects after multiple treatments.

Transcriptional-mediated effects of radiation on the expression of immune susceptibility markers in melanoma

BACKGROUND AND PURPOSE

We recently reported a time-sensitive, cooperative, anti-tumor effect elicited by radiation (RT) and intra-tumoral-immunocytokine injection in vivo. We hypothesized that RT triggers transcriptional-mediated changes in tumor expression of immune susceptibility markers at delayed time points, which may explain these previously observed time-dependent effects.

MATERIALS AND METHODS

We examined the time course of changes in expression of immune susceptibility markers following in vitro or in vivo RT in B78 murine melanoma and A375 human melanoma using flow cytometry, immunoblotting, and qPCR.

RESULTS

Flow cytometry and immunoblot revealed time-dependent increases in expression of death receptors and T cell co-stimulatory/co-inhibitory ligands following RT in murine and human melanoma. Using high-throughput qPCR, we observed comparable time courses of RT-induced transcriptional upregulation for multiple immune susceptibility markers. We confirmed analogous changes in B78 tumors irradiated in vivo. We observed upregulated expression of DNA damage response markers days prior to changes in immune markers, whereas phosphorylation of the STAT1 transcription factor occurred concurrently with changes following RT.

CONCLUSION

This study highlights time-dependent, transcription-mediated changes in tumor immune susceptibility marker expression following RT. These findings may help in the design of strategies to optimize sequencing of RT and immunotherapy in translational and clinical studies.

Cancer immunotherapy: how low-level ionizing radiation can play a key role

The cancer immunoediting hypothesis assumes that the immune system guards the host against the incipient cancer, but also "edits" the immunogenicity of surviving neoplastic cells and supports remodeling of tumor microenvironment towards an immunosuppressive and pro-neoplastic state. Local irradiation of tumors during standard radiotherapy, by killing neoplastic cells and generating inflammation, stimulates anti-cancer immunity and/or partially reverses cancer-promoting immunosuppression. These effects are induced by moderate (0.1-2.0 Gy) or high (>2 Gy) doses of ionizing radiation which can also harm normal tissues, impede immune functions, and increase the risk of secondary neoplasms. In contrast, such complications do not occur with exposures to low doses (≤0.1 Gy for acute irradiation or ≤0.1 mGy/min dose rate for chronic exposures) of low-LET ionizing radiation. Furthermore, considerable evidence indicates that such low-level radiation (LLR) exposures retard the development of neoplasms in humans and experimental animals. Here, we review immunosuppressive mechanisms induced by growing tumors as well as immunomodulatory effects of LLR evidently or likely associated with cancer-inhibiting outcomes of such exposures. We also offer suggestions how LLR may restore and/or stimulate effective anti-tumor immunity during the more advanced stages of carcinogenesis. We postulate that, based on epidemiological and experimental data amassed over the last few decades, whole- or half-body irradiations with LLR should be systematically examined for its potential to be a viable immunotherapeutic treatment option for patients with systemic cancer.

Gene and miRNA expression profiles of mouse Lewis lung carcinoma LLC1 cells following single or fractionated dose irradiation

In clinical practice ionizing radiation (IR) is primarily applied to cancer treatment in the form of fractionated dose (FD) irradiation. Despite this fact, a substantially higher amount of current knowledge in the field of radiobiology comes from in vitro studies based on the cellular response to single dose (SD) irradiation. In addition, intrinsic and acquired resistance to IR remains an issue in clinical practice, leading to radiotherapy treatment failure. Numerous previous studies suggest that an improved understanding of the molecular processes involved in the radiation-induced DNA damage response to FD irradiation could improve the effectiveness of radiotherapy. Therefore, the present study examined the differential expression of genes and microRNA (miRNA) in murine Lewis lung cancer (LLC)1 cells exposed to SD or FD irradiation. The results of the present study indicated that the gene and miRNA expression profiles of LLC1 cells exposed to irradiation were dose delivery type-dependent. Data analysis also revealed that mRNAs may be regulated by miRNAs in a radiation-dependent manner, suggesting that these mRNAs and miRNAs are the potential targets in the cellular response to SD or FD irradiation. However, LLC1 tumors after FD irradiation exhibited no significant changes in the expression of selected genes and miRNAs observed in the irradiated cells in vitro, suggesting that experimental in vitro conditions, particularly the tumor microenvironment, should be considered in detail to promote the development of efficient radiotherapy approaches. Nevertheless, the present study highlights the primary signaling pathways involved in the response of murine cancer cells to irradiation. Data presented in the present study can be applied to improve the outcome and development of radiotherapy in preclinical animal model settings.

Hypofractionated Irradiation Has Immune Stimulatory Potential and Induces a Timely Restricted Infiltration of Immune Cells in Colon Cancer Tumors

In addition to locally controlling the tumor, hypofractionated radiotherapy (RT) particularly aims to activate immune cells in the RT-modified microenvironment. Therefore, we examined whether hypofractionated RT can activate dendritic cells (DCs), induce immune cell infiltration in tumors, and how the chronology of immune cell migration into tumors occurs to gain knowledge for future definition of radiation breaks and inclusion of immunotherapy. Colorectal cancer treatments offer only limited survival benefit, and immunobiological principles for additional therapies need to be explored with preclinical models. The impact of hypofractionated RT on CT26 colon cancer tumor cell death, migration of DCs toward supernatants (SN) of tumor cells, and activation of DCs by SN were analyzed. The subcutaneous tumor of a BALB/c-CT26 mouse model was locally irradiated with 2 × 5 Gy, the tumor volume was monitored, and the infiltration of immune cells in the tumor was determined by flow cytometry daily. Hypofractionated RT induced a mixture of apoptotic and necrotic CT26 cells, which is known to be in particular immunogenic. DCs that migrated toward SN of CT26 cells particularly upregulated the activation markers CD80 and CD86 when in contact with SN of irradiated tumor cells. After hypofractionated RT, the tumor outgrowth was significantly retarded and in the irradiated tumors an increased infiltration of macrophages (CD11b^high/F4-80⁺) and DCs (MHC-II⁺), but only between day 5 and 10 after the first irradiation, takes place. While CD4⁺ T cells migrated into non-irradiated and irradiated tumors, CD8⁺ T cells were only found in tumors that had been irradiated and they were highly increased at day 8 after the first irradiation. Myeloid-derived suppressor cells and regulatory T cells show regular turnover in irradiated and non-irradiated tumors. Tumor cell-specific anti-IgM antibodies were enhanced in the serum of animals with irradiated tumors. We conclude that hypofractionated RT suffices to activate DCs and to induce infiltration of innate and adaptive immune cells into solid colorectal tumors. However, the presence of immune cells in the tumor which are beneficial for antitumor immune responses is timely restricted. These findings should be considered when innovative multimodal tumor treatment protocols of distinct RT with immune therapies are designed and clinically implemented.

Rationale and evidence to combine radiation therapy and immunotherapy for cancer treatment

Cancer immunotherapy exploits the immune system's ability to differentiate between tumor target cells and host cells. Except for limited success against a few tumor types, most immunotherapies have not achieved the desired clinical efficacy until recently. The field of cancer immunotherapy has flourished with a variety of new agents for clinical use, and remarkable progress has been made in the design of effective immunotherapeutic regimens. Furthermore, the therapeutic outcome of these novel agents is enhanced when combined with conventional cancer treatment modalities including radiotherapy (RT). An increasing number of studies have demonstrated the abscopal effect, an immunologic response occurring in cancer sites distant from irradiated areas. The present work reviews studies on the combination between RT and immunotherapy to induce synergistic and abscopal effects involved in cancer immunomodulation. Further insight into the complex interactions between the immune system and cancer cells in the tumor microenvironment, and their modulation by RT, may reveal the abscopal effect as a clinically relevant and reproducible event leading to improved cancer outcome.

Impact of Particle Irradiation on the Immune System: From the Clinic to Mars

Despite the generalized use of photon-based radiation (i.e., gamma rays and X-rays) to treat different cancer types, particle radiotherapy (i.e., protons and carbon ions) is becoming a popular, and more effective tool to treat specific tumors due to the improved physical properties and biological effectiveness. Current scientific evidence indicates that conventional radiation therapy affects the tumor immunological profile in a particular manner, which in turn, might induce beneficial effects both at local and systemic (i.e., abscopal effects) levels. The interaction between radiotherapy and the immune system is being explored to combine immune and radiation (including particles) treatments, which in many cases have a greater clinical effect than any of the therapies alone. Contrary to localized, clinical irradiation, astronauts are exposed to whole body, chronic cosmic radiation, where protons and heavy ions are an important component. The effects of this extreme environment during long periods of time, e.g., a potential mission to Mars, will have an impact on the immune system that could jeopardize the health of the astronauts, hence the success of the mission. To this background, the purpose of this mini review is to briefly present the current knowledge in local and systemic immune alterations triggered by particle irradiation and to propose new lines of future research. Immune effects induced by particle radiation relevant to clinical applications will be covered, together with examples of combined radiotherapy and immunotherapy. Then, the focus will move to outer space, where the immune system alterations induced by cosmic radiation during spaceflight will be discussed.

Radiotherapy and MVA-MUC1-IL-2 vaccine act synergistically for inducing specific immunity to MUC-1 tumor antigen

Background

We previously demonstrated that tumor irradiation potentiates cancer vaccines using genetic modification of tumor cells in murine tumor models. To investigate whether tumor irradiation augments the immune response to MUC1 tumor antigen, we have tested the efficacy of tumor irradiation combined with an MVA-MUC1-IL2 cancer vaccine (Transgene TG4010) for murine renal adenocarcinoma (Renca) cells transfected with MUC1.

Methods

Established subcutaneous Renca-MUC1 tumors were treated with 8 Gy radiation on day 11 and peritumoral injections of MVA-MUC1-IL2 vector on day 12 and 17, or using a reverse sequence of vaccine followed by radiation. Growth delays were monitored by tumor measurements and histological responses were evaluated by immunohistochemistry. Specific immunity was assessed by challenge with Renca-MUC1 cells. Generation of tumor-specific T cells was detected by IFN-γ production from splenocytes stimulated in vitro with tumor lysates using ELISPOT assays.

Results

Tumor growth delays observed by tumor irradiation combined with MVA-MUC1-IL-2 vaccine were significantly more prolonged than those observed by vaccine, radiation, or radiation with MVA empty vector. The sequence of cancer vaccine followed by radiation two days later resulted in 55–58% complete responders and 60% mouse long-term survival. This sequence was more effective than that of radiation followed by vaccine leading to 24–30% complete responders and 30% mouse survival. Responding mice were immune to challenge with Renca-MUC1 cells, indicating the induction of specific tumor immunity. Histology studies of regressing tumors at 1 week after therapy, revealed extensive tumor destruction and a heavy infiltration of CD45⁺ leukocytes including F4/80⁺ macrophages, CD8⁺ cytotoxic T cells and CD4⁺ helper T cells. The generation of tumor-specific T cells by combined therapy was confirmed by IFN-γ secretion in tumor-stimulated splenocytes. An abscopal effect was measured by rejection of an untreated tumor on the contralateral flank to the tumor treated with radiation and vaccine.

Conclusions

These findings suggest that cancer vaccine given prior to local tumor irradiation augments an immune response targeted at tumor antigens that results in specific anti-tumor immunity. These findings support further exploration of the combination of radiotherapy with cancer vaccines for the treatment of cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-016-0204-3) contains supplementary material, which is available to authorized users.

Radiation-induced immune responses: mechanisms and therapeutic perspectives

Recent advancement in the radiotherapy technology has allowed conformal delivery of high doses of ionizing radiation precisely to the tumors while sparing large volume of the normal tissues, which have led to better clinical responses. Despite this technological advancement many advanced tumors often recur and they do so within the previously irradiated regions. How could tumors recur after receiving such high ablative doses of radiation? In this review, we outlined how radiation can elicit anti-tumor responses by introducing some of the cytokines that can be induced by ionizing radiation. We then discuss how tumor hypoxia, a major limiting factor responsible for failure of radiotherapy, may also negatively impact the anti-tumor responses. In addition, we highlight how there may be other populations of immune cells including regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), and tumor-associated macrophages (TAMs) that can be recruited to tumors interfering with the anti-tumor immunity. Finally, the impact of irradiation on tumor hypoxia and the immune responses according to different radiotherapy regimen is also delineated. It is indeed an exciting time to see that radiotherapy is being combined with immunotherapy in the clinic and we hope that this review can add an excitement to the field.

The Role of the Membrane-Initiated Heat Shock Response in Cancer

The heat shock response (HSR) is a cellular response to diverse environmental and physiological stressors resulting in the induction of genes encoding molecular chaperones, proteases, and other proteins that are essential for protection and recovery from cellular damage. Since different perturbations cause accumulation of misfolded proteins, cells frequently encounter fluctuations in the environment which alter proteostasis. Since tumor cells use their natural adaptive mechanism of coping with stress and misfolded proteins, in recent years, the proteostasis network became a promising target for anti-tumor therapy. The membrane is the first to be affected by heat shock and therefore may be the first one to sense heat shock. The membrane also connects between the extracellular and the intracellular signals. Hence, there is a “cross talk” between the HSR and the membranes since heat shock can induce changes in the fluidity of membranes, leading to membrane lipid remodeling that occurs in several diseases such as cancer. During the last decade, a new possible therapy has emerged in which an external molecule is used that could induce membrane lipid re-organization. Since at the moment there are very few substances that regulate the HSR effectively, an alternative way has been searched to modulate chaperone activities through the plasma membrane. Recently, we suggested that the use of the membrane Transient Receptor Potential Vanilloid-1 (TRPV1) modulators regulated the HSR in cancer cells. However, the primary targets of the signal transduction pathway are yet un-known. This review provides an overview of the current literature regarding the role of HSR in membrane remodeling in cancer since a deep understanding of the membrane biology in cancer and the membrane heat sensing pathway is essential to design novel efficient therapies.

Increasing radiation dose improves immunotherapy outcome and prolongation of tumor dormancy in a subgroup of mice treated for advanced intracerebral melanoma

Previously, we developed a clinically relevant therapy model for advanced intracerebral B16 melanomas in syngeneic mice combining radiation and immunotherapies. Here, 7 days after B16-F10-luc2 melanoma cells were implanted intracerebrally (D7), syngeneic mice with bioluminescent tumors that had formed (1E10(5) to 7E10(6) photons per minute (>1E10(6), large; <1E10(6), small) were segregated into large-/small-balanced subgroups. Then, mice received either radiation therapy alone (RT) or radiation therapy plus immunotherapy (RT plus IT) (single injection of mAbPC61 to deplete regulatory T cells followed by multiple injections of irradiated granulocyte macrophage colony stimulating factor transfected B16-F10 cells) (RT plus IT). Radiation dose was varied (15, 18.75 or 22.5 Gy, given on D8), while immunotherapy was provided similarly to all mice. The data support the hypothesis that increasing radiation dose improves the outcome of immunotherapy in a subgroup of mice. The tumors that were greatly delayed in beginning their progressive growth were bioluminescent in vivo-some for many months, indicating prolonged tumor "dormancy," in some cases presaging long-term cures. Mice bearing such tumors had far more likely received radiation plus immunotherapy, rather than RT alone. Radiotherapy is a very important adjunct to immunotherapy; the greater the tumor debulking by RT, the greater should be the benefit to tumor immunotherapy.