Defining molecular signature of pro-immunogenic radiotherapy targets in human prostate cancer cells

PD-1 inhibitor combined with SBRT, GM-CSF, and thymosin alpha-1 in metastatic breast cancer: A case report and literature review

RATIONALE

Triple-negative breast cancer is characterized by a worse prognosis compared with other breast cancer subtypes, especially in the case of pretreated metastatic triple-negative breast cancer (mTNBC). Because of the limited treatment options and suboptimal response rates, there is a pressing need to explore novel treatment protocols.

PATIENT CONCERNS

A 48-year-old female patient diagnosed with mTNBC who had not responded to multiple lines of therapy (including surgery, chemotherapy, and radiotherapy) but demonstrated significant efficacy and abscopal effects after enrolling in our clinical trial.

DIAGNOSES

Triple-negative breast cancer with lung metastases.

INTERVENTIONS

The clinical trial combined stereotactic body radiotherapy, immunotherapy, granulocyte-macrophage colony-stimulating factor, and thymosin alpha-1 to treat previously treated metastatic solid cancers.

OUTCOMES

This combined treatment regimen implemented in this clinical trial yielded the patient's notable efficacy, accompanied by abscopal effects. The target lesion and the 3 observed lesions achieved a partial response according to the RECIST v1.1 criteria. reevaluation scans after 2 cycles of immunotherapy indicated a regression rate of -78.97% for the target lesion and -56.73% for the observed lesions. Hematological indexes were stable, and there was no apparent myelosuppression. Also, the tumor marker CA-199 exhibited a downward trend. During the course of treatment, the patient experienced a grade 2 skin reaction, which improved after receiving antiallergic treatment. No further adverse effects were observed.

LESSONS

This treatment regimen may offer a promising treatment strategy for patients with mTNBC and other metastatic solid cancers.

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.

A Partial Tumor Irradiation Approach for Complex Bulky Disease

A large proportion of cancer patients present with unresectable bulky disease at baseline or following treatment failure. The data available in the literature suggest that the vast majority of these patients do not benefit from available standard therapies. Therefore the clinical outcomes are poor; patients are desperate and usually relegated to palliative or best supportive care as the only options. Large tumor masses are usually hypoxic, resistant to radiation and systemic therapy, with extensive regional infiltration of the surrounding critical organs, the presence of which makes it impossible to deliver a radical dose of radiation. Promising data in terms of improved therapeutic ratio where such complex tumors are concerned can be seen with the use of new emerging unconventional radiotherapy techniques known as spatially fractionated radiotherapies (SFRT). One of them is PATHY, or PArtial Tumor irradiation targeting HYpoxic segment, which is characterized by a very short treatment course offering a large spectrum of therapeutic benefits in terms of the symptom relief, quality of life, local tumor control, neoadjuvant and immunomodulatory effects.

Immunotherapy and Radiotherapy Combinations for Sarcoma

Sarcomas are a heterogeneous group of bone and soft tissue tumors. Survival outcomes for advanced (unresectable or metastatic) disease remain poor, so therapeutic improvements are needed. Radiotherapy plays an integral role in the neoadjuvant and adjuvant treatment of localized disease as well as in the treatment of metastatic disease. Combining radiotherapy with immunotherapy to potentiate immunotherapy has been used in a variety of cancers other than sarcoma, and there is opportunity to further investigate combining immunotherapy with radiotherapy to try to improve outcomes in sarcoma. In this review, we describe the diversity of the tumor immune microenvironments for sarcomas and describe the immunomodulatory effects of radiotherapy. We discuss studies on the timing of radiotherapy relative to immunotherapy and studies on the radiotherapy dose and fractionation regimen to be used in combination with immunotherapy. We describe the impact of radiotherapy on the tumor immune microenvironment. We review completed and ongoing clinical trials combining radiotherapy with immunotherapy for sarcoma and propose future directions for studies combining immunotherapy with radiotherapy in the treatment of sarcoma.

Global research landscape and trends of cancer radiotherapy plus immunotherapy: A bibliometric analysis

The aim of this study was to present current research trends on the synergistic use of radiotherapy and immunotherapy (IRT) for cancer treatment. On March 1, 2023, we conducted a literature search for IRT papers using the Web of Science database. We extracted information and constructed two databases - the Core Database (CD) with 864 papers and Generalized Database (GD) with 6344 papers. A bibliometric analysis was performed to provide insights into the research landscape, to identify emerging trends and highly cited papers and journals in the field of IRT. The CD contained 864 papers that were collectively cited 31,818 times. Prominent journals in this area included the New England Journal of Medicine, Lancet Oncology, and the Journal of Clinical Oncology. Corresponding authors from the USA contributed the most publications. In recent years, lung cancer, melanoma, stereotactic radiotherapy, immune checkpoint inhibitors, and the tumor microenvironment emerged as hot research areas. This bibliometric analysis presented quantitative insights into research concerning IRT and proposed potential avenues for further exploration. Moreover, researchers can use our findings to select appropriate journals for publication or identify prospective collaborators. In summary, this bibliometric analysis provides a comprehensive overview of the historical progression and recent advancements in IRT research that may serve as inspiration for future investigations.

Irradiation Induces Gasdermin E-Triggered Tumor Immunity to Inhibit Esophageal Carcinoma Cell Survival

Gasdermin E (GSDME), an executor of pyroptosis, can be activated by caspase-3 and has been recognized as a tumor suppressor in various human cancers. In addition, caspase-3/GSDME signal-induced pyroptosis is a form of immunogenic cell death (ICD). In this study, we aimed to understand the association between radiotherapy and caspase-3/GSDME signal-related ICD in esophageal carcinoma (EC) cells. The expression of caspase-3 and GSDME in two EC cell lines, ECA-109 and KYSE-150, was silenced or overexpressed by transfection with specific siRNAs or overexpression vectors. Cells were subjected to 0-8 Gy irradiation, and cell death was evaluated by CCK-8 assay, annexin V-FITC staining, lactate dehydrogenase (LDH) detection kit, Western blotting, and immunofluorescence. Irradiation in both EC cell lines promoted dose-dependent viability loss and apoptosis. More specifically, 8 Gy X-ray increased the apoptosis rate from 4.1 to 12.8% in ECA-109 cells and from 4.6 to 21.1% in KYSE-150 cells. In irradiated EC cells, the levels of LDH release and caspase-3/GSDME cleavage were increased. Caspase-3 silencing inhibited irradiation-induced GSDME cleavage and EC cell death. Furthermore, we identified the death of EC cells suppressed by caspase-3 siRNA, and the levels of CRT, HMGB1, HSP70, and HSP90 were also markedly downregulated by caspase-3 siRNA. Similarly, GSDME silencing diminished irradiation-induced EC cell death and the levels of ICD markers. Overexpression of caspase-3 and GSDME accelerated irradiation-induced ICD. In summary, irradiation in EC cells induces GSDME-mediated pyroptosis and activates ICD to inhibit esophageal carcinoma cell survival.

Irradiation-induced IFN-type-I pathway activation in prostate cancer cell lines

The Interferon (ΙFN) Type-I pathway has an important role in the activation of an anti-tumor immune response. We investigated the effects of two different dose fractionations of radiation (3 daily 8 Gy fractions vs. one fraction of 20 Gy) on the activation of the Type-I IFN-pathway in three hormone-dependent (22Rv1) and independent (DU145, PC3), prostate cancer (PC) cell lines. Regardless of the dose schedules, radiation-induced the expression of IFN-stimulated genes in all PC cell lines, with a strong up-regulation of the IFI6v2 and IFI44 genes. In addition, strong up-regulation of the MX1 and MX2 genes was noted in the PC3 cell line. This effect was independent of the expression of IFNβ, cGAS, or TREX1 levels. It is suggested that the RT-induced IFN type-I response could be exploited for the development of immuno-RT policies for localized and metastatic PC.

Emerging evidence for adapting radiotherapy to immunotherapy

Immunotherapy has revolutionized the clinical management of many malignancies but is infrequently associated with durable objective responses when used as a standalone treatment approach, calling for the development of combinatorial regimens with superior efficacy and acceptable toxicity. Radiotherapy, the most commonly used oncological treatment, has attracted considerable attention as a combination partner for immunotherapy owing to its well-known and predictable safety profile, widespread clinical availability, and potential for immunostimulatory effects. However, numerous randomized clinical trials investigating radiotherapy-immunotherapy combinations have failed to demonstrate a therapeutic benefit compared with either modality alone. Such a lack of interaction might reflect suboptimal study design, choice of end points and/or administration of radiotherapy according to standard schedules and target volumes. Indeed, radiotherapy has empirically evolved towards radiation doses and fields that enable maximal cancer cell killing with manageable toxicity to healthy tissues, without much consideration of potential radiation-induced immunostimulatory effects. Herein, we propose the concept that successful radiotherapy-immunotherapy combinations might require modifications of standard radiotherapy regimens and target volumes to optimally sustain immune fitness and enhance the antitumour immune response in support of meaningful clinical benefits.

Machine learning in non-small cell lung cancer radiotherapy: A bibliometric analysis

Background

Machine learning is now well-developed in non-small cell lung cancer (NSCLC) radiotherapy. But the research trend and hotspots are still unclear. To investigate the progress in machine learning in radiotherapy NSCLC, we performed a bibliometric analysis of associated research and discuss the current research hotspots and potential hot areas in the future.

Methods

The involved researches were obtained from the Web of Science Core Collection database (WoSCC). We used R-studio software, the Bibliometrix package and VOSviewer (Version 1.6.18) software to perform bibliometric analysis.

Results

We found 197 publications about machine learning in radiotherapy for NSCLC in the WoSCC, and the journal Medical Physics contributed the most articles. The University of Texas MD Anderson Cancer Center was the most frequent publishing institution, and the United States contributed most of the publications. In our bibliometric analysis, “radiomics” was the most frequent keyword, and we found that machine learning is mainly applied to analyze medical images in the radiotherapy of NSCLC.

Results

The research we identified about machine learning in NSCLC radiotherapy was mainly related to the radiotherapy planning of NSCLC and the prediction of treatment effects and adverse events in NSCLC patients who were under radiotherapy. Our research has added new insights into machine learning in NSCLC radiotherapy and could help researchers better identify hot research areas in the future.

Combining chemotherapy and tislelizumab with preoperative split-course hypofraction radiotherapy for locally advanced rectal cancer: study protocol of a prospective, single-arm, phase II trial

INTRODUCTION

Short-course radiotherapy (SCRT) with systemic therapy has the potential to further improve the long-term efficacy in patients with locally advanced rectal cancer (LARC). To maximise the benefits of neoadjuvant therapy for improved prognosis, it is important to determine the optimal mix of chemotherapy, immunotherapy and SCRT.

METHODS AND ANALYSIS

Fifty treatment-naïve patients with operable LARC (T3-4 and/or N+) will be recruited. Patients will be synchronously treated with capecitabine plus oxaliplatin (CAPOX) chemotherapy, tislelizumab and preoperative split-course hypofraction radiotherapy (SCHR) (5×7 Gy) before surgery. Chemotherapy for CAPOX starts on day 1 of every 21-day cycle: on day 1, oxaliplatin 130 mg/m² will be injected intravenously. On days 1-14, capecitabine 1000 mg/m² was ingested two times a day. Simultaneously, tocilizumab 200 mg will be given intravenously on the first day of every 21-day cycle. A single 7 Gy SCHR treatment (day 7 of each 21-day cycle) will be delivered five times during the seventh day of treatment. The primary endpoint will be pathological complete response. The secondary outcomes will be the 3-year disease-free survival, local recurrence rate, overall survival, sphincter-sparing surgery rate, R0 resection rate, predictive biomarkers and quality of life.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of Xiehe Affiliated Hospital of Fujian Medical University (XAHFMU) (No. 2021YF025-01). Results from our study will be disseminated in international peer-reviewed journals. All study procedures were developed in order to assure data protection and confidentiality.

TRIAL REGISTRATION NUMBER

NCT05176964.

Radiation-Induced Remodeling of the Tumor Microenvironment Through Tumor Cell-Intrinsic Expression of cGAS-STING in Esophageal Squamous Cell Carcinoma

PURPOSE

Radiation therapy (RT) has the potential to activate the tumor-microenvironment (TME) and promote the efficacy of immune checkpoint blockade therapy. Tumor cell-intrinsic expression of cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) plays an important role in regulations of radiation-induced activation of immune cells in the TME. However, the role of tumor cell-intrinsic cGAS-STING in radiation-mediated remodeling of the TME in esophageal squamous cell carcinoma (ESCC) is not completely understood; thus, we investigated its effect on the radiation-mediated remodeling of the TME in ESCC.

METHODS

We assessed the effect of tumor cell-intrinsic cGAS-STING on the expression of mediators of the immune system, including type I interferon, T-cell chemo-attractants, colony-stimulating factor-1, and interleukin 34 (IL-34), induced by radiation in ESCC cell lines. We also quantified the association between tumor cell-intrinsic expression of cGAS-STING and infiltrations of immune cells, including CD8⁺ T cells and CD163⁺ M2-tumor-associated macrophages (TAMs), in ESCC tissues before and after neoadjuvant chemo-RT (n = 47).

RESULTS

We found that tumor cell-intrinsic expression of cGAS-STING was involved in radiation-induced infiltration of CD8⁺ T cells and expression of type I interferon and T-cell chemo-attractants in ESCC cells. Surprisingly, tumor cell-intrinsic cGAS-STING was also involved in radiation-triggered infiltration and/or M2-polarization of CD163⁺ TAMs and expression of IL-34, an important cytokine for recruitment and M2-polarization of TAMs, in ESCC cells. The number of CD163⁺ M2-TAMs was significantly associated with IL-34 expression in tumor cells in irradiated ESCC tissues.

CONCLUSIONS

The tumor cell-intrinsic expression of cGAS-STING is essential for radiation-induced activation of immune cells in the TME, but it is also involved in the recruitment of tumor-promoting M2-TAMs in ESCC. Therefore, blocking of M2-TAM infiltration by targeting IL-34 might improve the efficacy of RT and combination therapy of RT with immune checkpoint inhibitors in ESCC.

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.

Research progress in inducing immunogenic cell death of tumor cells

Immunogenic cell death (ICD) is a regulated cell death (RCD) pathway. In response to physical and chemical signals, tumor cells activate specific signaling pathways that stimulate stress responses in the endoplasmic reticulum (ER) and expose damage-associated molecular patterns (DAMPs), which promote antitumor immune responses. As a result, the tumor microenvironment is altered, and many tumor cells are killed. The ICD response in tumor cells requires inducers. These inducers can be from different sources and contribute to the development of the ICD either indirectly or directly. The combination of ICD inducers with other tumor treatments further enhances the immune response in tumor cells, and more tumor cells are killed; however, it also produces side effects of varying severity. New induction methods based on nanotechnology improve the antitumor ability and significantly reduces side effects because they can target tumor cells precisely. In this review, we introduce the characteristics and mechanisms of ICD responses in tumor cells and the DAMPs associated with ICD responses, summarize the current methods of inducing ICD response in tumor cells in five distinct categories: chemical sources, physical sources, pathogenic sources, combination therapies, and innovative therapies. At the same time, we introduce the limitations of current ICD inducers and make a summary of the use of ICD responses in clinical trials. Finally, we provide an outlook on the future of ICD inducer development and provide some constructive suggestions.

Long-term expression changes of immune-related genes in prostate cancer after radiotherapy

The expression of immune-related genes in cancer cells can alter the anti-tumor immune response and thereby impact patient outcomes. Radiotherapy has been shown to modulate immune-related genes dependent on the fractionation regimen. To identify long-term changes in gene expression after irradiation, PC3 (p53 deleted) and LNCaP (p53 wildtype) prostate cancer cells were irradiated with either a single dose (SD, 10 Gy) or a fractionated regimen (MF) of 10 fractions (1 Gy per fraction). Whole human genome arrays were used to determine gene expression at 24 h and 2 months after irradiation. Immune pathway activation was analyzed with Ingenuity Pathway Analysis software. Additionally, 3D colony formation assays and T-cell cytotoxicity assays were performed. LNCaP had a higher basal expression of immunogenic genes and was more efficiently killed by cytotoxic T-cells compared to PC3. In both cell lines, MF irradiation resulted in an increase in multiple immune-related genes immediately after irradiation, while at 2 months, SD irradiation had a more pronounced effect on radiation-induced gene expression. Both immunogenic and immunosuppressive genes were upregulated in the long term in PC3 cells by a 10 Gy SD irradiation but not in LNCaP. T-cell-mediated cytotoxicity was significantly increased in 10 Gy SD PC3 cells compared to the unirradiated control and could be further enhanced by treatment with immune checkpoint inhibitors. Irradiation impacts the expression of immune-related genes in cancer cells in a fractionation-dependent manner. Understanding and targeting these changes may be a promising strategy for primary prostate cancer and recurrent tumors.

Fatty acid oxidation fuels glioblastoma radioresistance with CD47-mediated immune evasion

Glioblastoma multiforme (GBM) remains the top challenge to radiotherapy with only 25% one-year survival after diagnosis. Here, we reveal that co-enhancement of mitochondrial fatty acid oxidation (FAO) enzymes (CPT1A, CPT2 and ACAD9) and immune checkpoint CD47 is dominant in recurrent GBM patients with poor prognosis. A glycolysis-to-FAO metabolic rewiring is associated with CD47 anti-phagocytosis in radioresistant GBM cells and regrown GBM after radiation in syngeneic mice. Inhibition of FAO by CPT1 inhibitor etomoxir or CRISPR-generated CPT1A^-/-, CPT2^-/-, ACAD9^-/- cells demonstrate that FAO-derived acetyl-CoA upregulates CD47 transcription via NF-κB/RelA acetylation. Blocking FAO impairs tumor growth and reduces CD47 anti-phagocytosis. Etomoxir combined with anti-CD47 antibody synergizes radiation control of regrown tumors with boosted macrophage phagocytosis. These results demonstrate that enhanced fat acid metabolism promotes aggressive growth of GBM with CD47-mediated immune evasion. The FAO-CD47 axis may be targeted to improve GBM control by eliminating the radioresistant phagocytosis-proofing tumor cells in GBM radioimmunotherapy.

Investigating the Role of Obesity in Prostate Cancer and Identifying Biomarkers for Drug Discovery: Systems Biology and Deep Learning Approaches

Prostate cancer (PCa) is the second most frequently diagnosed cancer for men and is viewed as the fifth leading cause of death worldwide. The body mass index (BMI) is taken as a vital criterion to elucidate the association between obesity and PCa. In this study, systematic methods are employed to investigate how obesity influences the noncutaneous malignancies of PCa. By comparing the core signaling pathways of lean and obese patients with PCa, we are able to investigate the relationships between obesity and pathogenic mechanisms and identify significant biomarkers as drug targets for drug discovery. Regarding drug design specifications, we take drug–target interaction, drug regulation ability, and drug toxicity into account. One deep neural network (DNN)-based drug–target interaction (DTI) model is trained in advance for predicting drug candidates based on the identified biomarkers. In terms of the application of the DNN-based DTI model and the consideration of drug design specifications, we suggest two potential multiple-molecule drugs to prevent PCa (covering lean and obese PCa) and obesity-specific PCa, respectively. The proposed multiple-molecule drugs (apigenin, digoxin, and orlistat) not only help to prevent PCa, suppressing malignant metastasis, but also result in lower production of fatty acids and cholesterol, especially for obesity-specific PCa.

Immunogenic Cell Death Induction by Ionizing Radiation

Immunogenic cell death (ICD) is a form of regulated cell death (RCD) induced by various stresses and produces antitumor immunity via damage-associated molecular patterns (DAMPs) release or exposure, mainly including high mobility group box 1 (HMGB1), calreticulin (CRT), adenosine triphosphate (ATP), and heat shock proteins (HSPs). Emerging evidence has suggested that ionizing radiation (IR) can induce ICD, and the dose, type, and fractionation of irradiation influence the induction of ICD. At present, IR-induced ICD is mainly verified in vitro in mice and there is few clinical evidence about it. To boost the induction of ICD by IR, some strategies have shown synergy with IR to enhance antitumor immune response, such as hyperthermia, nanoparticles, and chemotherapy. In this review, we focus on the molecular mechanisms of ICD, ICD-promoting factors associated with irradiation, the clinical evidence of ICD, and immunogenic forms of cell death. Finally, we summarize various methods of improving ICD induced by IR.

Interferon- and STING-independent induction of type I interferon stimulated genes during fractionated irradiation

BACKGROUND

Improvement of radiotherapy efficacy requires better insight in the dynamic responses that occur during irradiation. Here, we aimed to identify the molecular responses that are triggered during clinically applied fractionated irradiation.

METHODS

Gene expression analysis was performed by RNAseq or microarray analysis of cancer cells or xenograft tumors, respectively, subjected to 3-5 weeks of 5 × 2 Gy/week. Validation of altered gene expression was performed by qPCR and/or ELISA in multiple cancer cell lines as well as in pre- and on-treatment biopsies from esophageal cancer patients ( NCT02072720 ). Targeted protein inhibition and CRISPR/Cas-induced gene knockout was used to analyze the role of type I interferons and cGAS/STING signaling pathway in the molecular and cellular response to fractionated irradiation.

RESULTS

Gene expression analysis identified type I interferon signaling as the most significantly enriched biological process induced during fractionated irradiation. The commonality of this response was confirmed in all irradiated cell lines, the xenograft tumors and in biopsies from esophageal cancer patients. Time-course analyses demonstrated a peak in interferon-stimulated gene (ISG) expression within 2-3 weeks of treatment. The response was accompanied by a variable induction of predominantly interferon-beta and/or -lambda, but blocking these interferons did not affect ISG expression induction. The same was true for targeted inhibition of the upstream regulatory STING protein while knockout of STING expression only delayed the ISG expression induction.

CONCLUSIONS

Collectively, the presented data show that clinically applied fractionated low-dose irradiation can induce a delayed type I interferon response that occurs independently of interferon expression or STING signaling. These findings have implications for current efforts that aim to target the type I interferon response for cancer treatment.

Combinations using checkpoint blockade to overcome resistance

The advent of immunotherapy for cancer represented a paradigm shift in the treatment approach of neoplasia. Immune-checkpoint inhibitors (ICIs) were demonstrated to significantly improve outcomes, including overall survival across several cancer types, with yearly-durable responses. Nevertheless, many patients derive minor or no benefit with immune checkpoint (IC)-blockade, including patients with cancer types traditionally considered immunogenic. Combination strategies of ICIs with chemotherapy, radiotherapy, targeted therapies or other immunotherapy compounds have been conceived in order to boost the immune-responses and potentially overcome resistance to ICIs. This review focuses on mechanisms underlying resistance to IC-blockade and provides an overview of potential advantages and limitations of combination strategies currently under investigation.

Immunotherapy Moves to the Early-Stage Setting in Non-Small Cell Lung Cancer: Emerging Evidence and the Role of Biomarkers

Despite numerous advances in targeted therapy and immunotherapy in the last decade, lung cancer continues to present the highest mortality rate of all cancers. Targeted therapy based on specific genomic alterations, together with PD-1 and CTLA-4 axis blocking-based immunotherapy, have significantly improved survival in advanced non-small cell lung cancer (NSCLC) and both therapies are now well-established in this clinical setting. However, it is time for immunotherapy to be applied in patients with early-stage disease, which would be an important qualitative leap in the treatment of lung cancer patients with curative intent. Preliminary data from a multitude of studies are highly promising, but therapeutic decision-making should be guided by an understanding of the molecular features of the tumour and host. In the present review, we discuss the most recently published studies and ongoing clinical trials, controversies, future challenges and the role of biomarkers in the selection of best therapeutic options.

Radiation-induced Adaptive Response: New Potential for Cancer Treatment

Radiotherapy is highly effective due to its ability to physically focus the treatment to target the tumor while sparing normal tissue and its ability to be combined with systemic therapy. This systemic therapy can be utilized before radiotherapy as an adjuvant or induction treatment, during radiotherapy as a radiation "sensitizer," or following radiotherapy as a part of combined modality therapy. As part of a unique concept of using radiation as "focused biology," we investigated how tumors and normal tissues adapt to clinically relevant multifraction (MF) and single-dose (SD) radiation to observe whether the adaptations can induce susceptibility to cell killing by available drugs or by immune enhancement. We identified an adaptation occurring after MF (3 × 2 Gy) that induced cell killing when AKT-mTOR inhibitors were delivered following cessation of radiotherapy. In addition, we identified inducible changes in integrin expression 2 months following cessation of radiotherapy that differ between MF (1 Gy × 10) and SD (10 Gy) that remain targetable compared with preradiotherapy. Adaptation is reflected across different "omics" studies, and thus the range of possible molecular targets is not only broad but also time, dose, and schedule dependent. While much remains to be studied about the radiation adaptive response, radiation should be characterized by its molecular perturbations in addition to physical dose. Consideration of the adaptive effects should result in the design of a tailored radiotherapy treatment plan that accounts for specific molecular changes to be targeted as part of precision multimodality cancer treatment.

Chemotherapy-based split stereotactic body radiation therapy for borderline resectable and locally advanced pancreatic cancer: study protocol of a prospective, single-arm phase II trial

INTRODUCTION

The question of how to administer adequate chemotherapy to synchronise stereotactic body radiation therapy (SBRT) treatment strategy to maximise the benefits of neoadjuvant therapy for the improved prognosis of patients with borderline resectable (BRPC) and locally advanced (LAPC) pancreatic cancer is a challenging and debatable issue. No studies have yet evaluated the efficacy of split-course SBRT as the neoadjuvant chemoradiotherapy regimen. We aimed to study whether neoadjuvant chemotherapy plus split-course SBRT results in better outcomes in BRPC and LAPC patients.

METHODS AND ANALYSIS

Treatment-naïve patients with radiographically confirmed BRPC or LAPC, supporting biopsy results and no severe comorbidities will be enrolled. They will be treated with nab-paclitaxel plus gemcitabine (nab-P+Gem) chemotherapy plus split-course SBRT, followed by an investigator's choice of continuation of treatment with nab-P+Gem or surgery. nab-P+Gem chemotherapy will commence on day 1 for each of six cycles: nab-paclitaxel 125 mg/m² intravenous infusion over approximately 30-45 min, followed by gemcitabine 1000 mg/m² intravenous infusion over about 30 min on days 1 and 15 of each 28-day cycle. During the first and second cycles of chemotherapy, SBRT will be given as a single irradiation of 10 Gy four times (days 2 and 16 of each 28-day cycle). The primary endpoint is progression-free survival; while the secondary outcomes are the time to treatment failure, disease control rate, overall response rate, overall survival, R0 resection rate and incidence of adverse effects.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of Xiehe Affiliated Hospital of Fujian Medical University (No. 2019YF015-01). Results from our study will be disseminated in international peer-reviewed journals. All study procedures were developed in order to assure data protection and confidentiality.

TRIAL REGISTRATION NUMBER

NCT04289792.

Harnessing the potential of multimodal radiotherapy in prostate cancer

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

Sixteenth Annual Warren K. Sinclair Keynote Address: Frontiers in Medical Radiation Science

On the occasion of the 90 anniversary of National Council on Radiation Protection and Measurements (NCRP) and its 55 anniversary since being Congressionally Chartered, the theme of "Providing Best Answers to Your Most Pressing Questions about Radiation" is most appropriate. The question proposed here is, "What are the new frontiers for the NCRP with its breadth of talent and expertise in the rapidly evolving era of precision medicine?" Three closely related themes are presented for new applications of radiation science for research and career opportunities: (1) introduction of the new concept of defining radiation dose in biological perturbations in addition to physical dose, particularly for cancer treatment; (2) assessment of early biomarkers of radiation injury for mass casualty exposure (biodosimetry) to guide triage and for clinical application to guide radiation therapy; and (3) proposal to expand opportunities for radiation professionals, including consideration of a new training program within NCRP's "Where are the radiation professionals?" initiative that trains radiation oncologists as molecular radiation epidemiologists.

Radiation as an In Situ Auto-Vaccination: Current Perspectives and Challenges

Radiotherapy is generally considered to be a local treatment, but there have been reports of rare cases demonstrating abscopal effects in which antitumor effects have been observed in cancer lesions other than the irradiated site. This result is more likely to occur when immune checkpoint inhibitors are used in addition to radiotherapy. Certain radiation-induced chemokines and cytokines have immune-enhancing effects. Immune checkpoint inhibitors may strengthen these effects by stimulating antigen-presenting cells and effector cytotoxic T cells. To date, there is no consensus regarding the applicability of the abscopal effect in the clinical setting, including optimal methods for combining immune checkpoint inhibitors and irradiation. In this review, we highlight the evidence for interactions between cancer immunotherapy and radiotherapy and discuss the potential of such interactions for use in designing novel combination therapies.

The Reciprocity between Radiotherapy and Cancer Immunotherapy

The clinical success of immune checkpoint inhibitors in treating metastatic and refractory cancers has generated significant interest in investigating their role in treating locally advanced diseases, thus requiring them to be combined with standard treatments in the hope of producing synergistic antitumor responses. Radiotherapy, in particular, has long been hypothesized to have actions complementary to those of immune checkpoint blockade, and a growing body of evidence indicates that cancer immunotherapy may also have radiosensitizing effects, which would provide unique benefit for locoregional treatments. Recent studies have demonstrated that when immune cells are activated by immunotherapeutics, they can reprogram the tumor microenvironment in ways that may potentially increase the radiosensitivity of the tumor. In this review, we highlight the evidence that supports reciprocal interactions between cancer immunotherapy and radiotherapy, where in addition to the traditional notion that radiation serves to enhance the activation of antitumor immunity, an alternative scenario also exists in which T-cell activation by cancer immunotherapy may sensitize tumors to radiation treatment through mechanisms that include normalization of the tumor vasculature and tissue hypoxia. We describe the empirical observations from preclinical models that support such effects and discuss their implications for future research and trial design.

Synergistic effect of immunotherapy and radiotherapy in non-small cell lung cancer: current clinical trials and prospective challenges

Lately, the success of ICIs has drastically changed the landscape of cancer treatment, and several immune checkpoint inhibitors (ICIs) have been approved by the US Food and Drug Administration (FDA) for advanced non-small cell lung cancer (NSCLC). However, numerous patients are resistant to ICIs and require additional procedures for better efficacy results. Thus, combination therapy is urgently needed to strengthen the anti-tumor immunity. A variety of preclinical and clinical studies combining ICIs with radiotherapy (RT) have demonstrated that the combination could induce synergistic effects, as RT overcomes the resistance to ICIs. However, the underlying mechanism of the synergistic effect and the optimal arrangement of the combination therapy are indecisive now. Hence, this review was conducted to provide an update on the current clinical trial results and highlighted the ongoing trials. We also discussed the optimal parameters in clinical trials, including radiation dose, radiation fractionation, radiation target field, and sequencing of combination therapy. In this review, we found that combination therapy showed stronger anti-tumor immunity with tolerable toxicities in clinical trials. However, the best combination mode and potential biomarkers for the target patients in combination therapy are still unclear.

Long-term Tumor Adaptation after Radiotherapy: Therapeutic Implications for Targeting Integrins in Prostate Cancer

Adaptation of tumor cells to radiotherapy induces changes that are actionable by molecular targeted agents and immunotherapy. This report demonstrates that radiation-induced changes in integrin expression can be targeted 2 months later. Integrins are transmembrane cell adhesion molecules that are essential for cancer cell survival and proliferation. To analyze the short- and long-term effects of radiation on the integrin expression, prostate cancer cells (DU145, PC3, and LNCaP) were cultured in a 3D extracellular matrix and irradiated with either a single dose of radiation (2-10 Gy) or a multifractionated regimen (2-10 fractions of 1 Gy). Whole human genome microarrays, immunoblotting, immunoprecipitation assays, and immunofluorescence staining of integrins were performed. The results were confirmed in a prostate cancer xenograft model system. Interestingly, β1 and β4 integrins (ITGB1 and ITGB4) were upregulated after radiation in vitro and in vivo. This overexpression lasted for more than 2 months and was dose dependent. Moreover, radiation-induced upregulation of β1 and β4 integrin resulted in significantly increased tumor cell death after treatment with inhibitory antibodies. Combined, these findings indicate that long-term tumor adaptation to radiation can result in an increased susceptibility of surviving cancer cells to molecular targeted therapy due to a radiation-induced overexpression of the target. IMPLICATIONS: Radiation induces dose- and schedule-dependent adaptive changes that are targetable for an extended time; thus suggesting radiotherapy as a unique strategy to orchestrate molecular processes, thereby providing new radiation-drug treatment options within precision cancer medicine.

Combining Immunotherapy and Radiotherapy for Cancer Treatment: Current Challenges and Future Directions

Since the approval of anti-CTLA4 therapy (ipilimumab) for late-stage melanoma in 2011, the development of anticancer immunotherapy agents has thrived. The success of many immune-checkpoint inhibitors has drastically changed the landscape of cancer treatment. For some types of cancer, monotherapy for targeting immune checkpoint pathways has proven more effective than traditional therapies, and combining immunotherapy with current treatment strategies may yield even better outcomes. Numerous preclinical studies have suggested that combining immunotherapy with radiotherapy could be a promising strategy for synergistic enhancement of treatment efficacy. Radiation delivered to the tumor site affects both tumor cells and surrounding stromal cells. Radiation-induced cancer cell damage exposes tumor-specific antigens that make them visible to immune surveillance and promotes the priming and activation of cytotoxic T cells. Radiation-induced modulation of the tumor microenvironment may also facilitate the recruitment and infiltration of immune cells. This unique relationship is the rationale for combining radiation with immune checkpoint blockade. Enhanced tumor recognition and immune cell targeting with checkpoint blockade may unleash the immune system to eliminate the cancer cells. However, challenges remain to be addressed to maximize the efficacy of this promising combination. Here we summarize the mechanisms of radiation and immune system interaction, and we discuss current challenges in radiation and immune checkpoint blockade therapy and possible future approaches to boost this combination.

No role of IFITM3 in brain tumor formation in vivo

Glioblastoma multiforme (GBM) is one of the most lethal solid tumors in adults. Despite aggressive treatment approaches for patients, GBM recurrence is inevitable, in part due to the existence of stem-like brain tumor-propagating cells (BTPCs), which produce factors rendering them resistant to radio- and chemotherapy. Comparative transcriptome analysis of irradiated, patient-derived BTPCs revealed a significant upregulation of the interferon-inducible transmembrane protein 3 (IFITM3), suggesting the protein as a factor mediating radio resistance. Previously, IFITM3 has been described to affect glioma cells; therefore, the role of IFITM3 in the formation and progression of brain tumors has been investigated in vivo. Intracranial implantation studies using radio-selected BTPCs alongside non-irradiated parental BTPCs in immunodeficient mice displayed no influence of irradiation on animal survival. Furthermore, gain and loss of function studies using BTPCs ectopically expressing IFITM3 or having IFITM3 down-modulated by a shRNA approach, did affect neither tumor growth nor animal survival. Additionally, a syngeneic model based on the mouse glioma cell line GL261 was applied in order to consider the possibility that IFITM3 relies on an intact immune system to unfold its tumorigenic potential. GL261 cells ectopically expressing IFITM3 were implanted into the striatum of immunocompetent mice without influencing the survival of glioma-bearing animals. Lastly, the vasculature and the extent of microglia/macrophage invasion into the tumor were studied in BTPC and GL261 tumors but neither parameter was altered by IFITM3. This report presents for the first time that IFITM3 is upregulated in patient-derived BTPCs upon irradiation but does not affect brain tumor formation or progression in vivo.

Zerumbone Regulates DNA Repair Responding to Ionizing Radiation and Enhances Radiosensitivity of Human Prostatic Cancer Cells

Introduction. Radiation therapy using ionizing radiation is widely used for the treatment of prostate cancer. The intrinsic radiation sensitivity of cancer cells could be enhanced by modulating multiple factors including the capacity to repair DNA damage, especially double-strand breaks (DSBs). We aimed to examine the effect of zerumbone on radiation sensitivity and its protective effects against ionizing radiation–induced DSB in human prostate cancer cells. Materials and Methods. The human prostate cancer PC3 and DU145 cell lines were used. A colony formation assay was performed to analyze the radiation survival of cells. DNA histogram and generation of reactive oxygen species (ROS) were examined using flow cytometry. Western blotting was used to examine the expression of regulatory molecules related to DNA damage repair. Results. Pretreatment with zerumbone enhanced the radiation effect on prostate cancer cells. Zerumbone delayed the abrogation of radiation-induced expression of γ-H2AX, an indicator of DNA DSB. Zerumbone pretreatment markedly reduced ionizing radiation–induced upregulated expression of phosphorylated ATM (ataxia telangiectasia-mutated), which was partially reversed by the ATM agonist methyl methanesulfonate. Ionizing radiation augmented and zerumbone pretreatment reduced the expression of Jak2 and Stat3, which are involved in DNA damage repair signaling. No significant effect on the generation of ROS and expression of ATR was noted after zerumbone treatment. Conclusion: Zerumbone sensitized DU145 and PC3 prostatic cancer cells to ionizing radiation by modulating radiation-induced ATM activation during repair of DNA DSBs.

The Radiation Stress Response: Of the People, By the People and For the People

The radiation stress response can have broad impact. In this Failla Award presentation it is discussed in three components using terms relevant to the current political season as to how the radiation stress response can be applied to the benefit for cancer care and as service to society. Of the people refers to the impact of radiation on cells, tissues and patients. The paradigm our laboratory uses is radiation as a drug, called "focused biology", and physics as "nano-IMRT" because at the nanometer level physics and biology merge. By the people refers to how the general population often reacts to the word "radiation" and how the Radiation Research Society can better enable society to deal with the current realities of radiation in our lives. For the people refers to the potential for radiation oncology and radiation sciences to improve the lives of millions of people globally who are now beyond benefits of cancer treatment and research.

Exploiting Gene Expression Kinetics in Conventional Radiotherapy, Hyperfractionation, and Hypofractionation for Targeted Therapy

The dramatic changes in the technological delivery of radiation therapy, the repertoire of molecular targets for which pathway inhibitors are available, and the cellular and immunologic responses that can alter long-term clinical outcome provide a potentially unique role for using the radiation-inducible changes as therapeutic targets. Various mathematical models of dose and fractionation are extraordinarily useful in guiding treatment regimens. However, although the model may fit the clinical outcome, a deeper understanding of the molecular and cellular effect of the individual dose size and the adaptation to repeated exposure, called multifraction (MF) adaptation, may provide new therapeutic targets for use in combined modality treatments using radiochemotherapy and radioimmunotherapy. We discuss the potential of using different radiation doses and MF adaptation for targeting transcription factors, immune and inflammatory response, and cell "stemness." Given the complex genetic composition of tumors before treatment and their adaptation to drug treatment, innovative combinations using both the pretreatment molecular data and also the MF-adaptive response to radiation may provide an important role for focused radiation therapy as an integral part of precision medicine and immunotherapy.

Modern Radiotherapy Concepts and the Impact of Radiation on Immune Activation

Even though there is extensive research carried out in radiation oncology, most of the clinical studies focus on the effects of radiation on the local tumor tissue and deal with normal tissue side effects. The influence of dose fractionation and timing particularly with regard to immune activation is not satisfactorily investigated so far. This review, therefore, summarizes current knowledge on concepts of modern radiotherapy (RT) and evaluates the potential of RT for immune activation. Focus is set on radiation-induced forms of tumor cell death and consecutively the immunogenicity of the tumor cells. The so-called non-targeted, abscopal effects can contribute to anti-tumor responses in a specific and systemic manner and possess the ability to target relapsing tumor cells as well as metastases. The impact of distinct RT concepts on immune activation is outlined and pre-clinical evidence and clinical observations on RT-induced immunity will be discussed. Knowledge on the radiosensitivity of immune cells as well as clinical evidence for enhanced immunity after RT will be considered. While stereotactic ablative body radiotherapy seem to have a beneficial outcome over classical RT fractionation in pre-clinical animal models, in vitro model systems suggest an advantage for classical fractionated RT for immune activation. Furthermore, the optimal approach may differ based on the tumor site and/or genetic signature. These facts highlight that clinical trials are urgently needed to identify whether high-dose RT is superior to induce anti-tumor immune responses compared to classical fractionated RT and in particular how the outcome is when RT is combined with immunotherapy in selected tumor entities.

Higher Initial DNA Damage and Persistent Cell Cycle Arrest after Carbon Ion Irradiation Compared to X-irradiation in Prostate and Colon Cancer Cells

The use of charged-particle beams, such as carbon ions, is becoming a more and more attractive treatment option for cancer therapy. Given the precise absorbed dose-localization and an increased biological effectiveness, this form of therapy is much more advantageous compared to conventional radiotherapy, and is currently being used for treatment of specific cancer types. The high ballistic accuracy of particle beams deposits the maximal dose to the tumor, while damage to the surrounding healthy tissue is limited. In order to better understand the underlying mechanisms responsible for the increased biological effectiveness, we investigated the DNA damage and repair kinetics and cell cycle progression in two p53 mutant cell lines, more specifically a prostate (PC3) and colon (Caco-2) cancer cell line, after exposure to different radiation qualities. Cells were irradiated with various absorbed doses (0, 0.5, and 2 Gy) of accelerated ¹³C-ions at the Grand Accélérateur National d’Ions Lourds facility (Caen, France) or with X-rays (0, 0.1, 0.5, 1, 2, and 5 Gy). Microscopic analysis of DNA double-strand breaks showed dose-dependent increases in γ-H2AX foci numbers and foci occupancy after exposure to both types of irradiation, in both cell lines. However, 24 h after exposure, residual damage was more pronounced after lower doses of carbon ion irradiation compared to X-irradiation. Flow cytometric analysis showed that carbon ion irradiation induced a permanent G2/M arrest in PC3 cells at lower doses (2 Gy) compared to X-rays (5 Gy), while in Caco-2 cells the G2/M arrest was transient after irradiation with X-rays (2 and 5 Gy) but persistent after exposure to carbon ions (2 Gy).

Immunotherapy and stereotactic ablative radiotherapy (ISABR): a curative approach?

Conventional radiotherapy, in addition to its well-established tumoricidal effects, can also activate the host immune system. Radiation therapy modulates tumour phenotypes, enhances antigen presentation and tumour immunogenicity, increases production of cytokines and alters the tumour microenvironment, enabling destruction of the tumour by the immune system. Investigating the combination of radiotherapy with immunotherapeutic agents, which also promote the host antitumour immune response is, therefore, a logical progression. As the spectrum of clinical use of stereotactic radiotherapy continues to broaden, the question arose as to whether the ablative radiation doses used can also stimulate immune responses and, if so, whether we can amplify these effects by combining immunotherapy and stereotactic ablative radiotherapy (SABR). In this Perspectives article, we explore the preclinical and clinical evidence supporting activation of the immune system following SABR. We then examine studies that provide data on the effectiveness of combining these two techniques - immunotherapy and SABR - in an approach that we have termed 'ISABR'. Lastly, we provide general guiding principles for the development of future clinical trials to investigate the efficacy of ISABR in the hope of generating further interest in these exciting developments.

Comprehensive molecular tumor profiling in radiation oncology: How it could be used for precision medicine

New technologies enabling the analysis of various molecules, including DNA, RNA, proteins and small metabolites, can aid in understanding the complex molecular processes in cancer cells. In particular, for the use of novel targeted therapeutics, elucidation of the mechanisms leading to cell death or survival is crucial to eliminate tumor resistance and optimize therapeutic efficacy. While some techniques, such as genomic analysis for identifying specific gene mutations or epigenetic testing of promoter methylation, are already in clinical use, other "omics-based" assays are still evolving. Here, we provide an overview of the current status of molecular profiling methods, including promising research strategies, as well as possible challenges, and their emerging role in radiation oncology.

Key mechanisms involved in ionizing radiation-induced systemic effects. A current review

Organisms respond to physical, chemical and biological threats by a potent inflammatory response, aimed at preserving tissue integrity and restoring tissue homeostasis and function. Systemic effects in an organism refer to an effect or phenomenon which originates at a specific point and can spread throughout the body affecting a group of organs or tissues. Ionizing radiation (IR)-induced systemic effects arise usually from a local exposure of an organ or part of the body. This stress induces a variety of responses in the irradiated cells/tissues, initiated by the DNA damage response and DNA repair (DDR/R), apoptosis or immune response, including inflammation. Activation of this IR-response (IRR) system, especially at the organism level, consists of several subsystems and exerts a variety of targeted and non-targeted effects. Based on the above, we believe that in order to understand this complex response system better one should follow a 'holistic' approach including all possible mechanisms and at all organization levels. In this review, we describe the current status of knowledge on the topic, as well as the key molecules and main mechanisms involved in the 'spreading' of the message throughout the body or cells. Last but not least, we discuss the danger-signal mediated systemic immune effects of radiotherapy for the clinical setup.

Immunomodulatory effects of radiation: what is next for cancer therapy?

Despite its former reputation as being immunosuppressive, it has become evident that radiation therapy can enhance antitumor immune responses. This quality can be harnessed by utilizing radiation as an adjuvant to cancer immunotherapies. Most studies combine the standard radiation dose and regimens indicated for the given disease state, with novel cancer immunotherapies. It has become apparent that low-dose radiation, as well as doses within the hypofractionated range, can modulate tumor cells making them better targets for immune cell reactivity. Herein, we describe the range of phenotypic changes induced in tumor cells by radiation, and explore the diverse mechanisms of immunogenic modulation reported at these doses. We also review the impact of these doses on the immune cell function of cytotoxic cells in vivo and in vitro.