The immune mechanisms of abscopal effect in radiation therapy

Proton stereotactic centralized ablative radiation therapy for treating bulky tumor: a treatment plan study

Objective

Stereotactic centralized/core ablative radiation therapy (SCART) is a novel radiotherapy approach. This study investigates the potential benefits of proton-based SCART (pSCART) by leveraging the dosimetric advantages of protons and integrating them with the SCART technique.

Methods

Five clinical cases previously treated with conventional proton therapy were selected for this study. The pSCART plans utilized a relative biological effectiveness (RBE) prescription dose of 24 Gy (RBE) × 3 fractions, with each plan consisting of three to five fields. The prescribed dose for the CyberKnife SCART was the highest value meeting the organs-at-risk (OARs) dose limits and the tumor edge dose limits. The dose distributions of the CyberKnife-based SCART and pSCART plans were compared using five criteria: i) prescription dose; ii) 80% prescription dose volume, targets coverage at 80% and 20% dose levels, and the 80%/20% ratio; iii) volume receiving >5 Gy outside the tumor edge; iv) dose tolerance limits to OARs; and v) mean dose to OARs.

Results

pSCART can deliver a higher prescription dose of 24 Gy × 3 fractions versus SCART's 15 Gy × 2-3 fractions or 18 Gy × 2 fractions. Specifically, pSCART outperforms SCART in terms of the 80% prescription dose volume and 80% dose level coverage of stereotactic centralized/core target volumes (SCTV) achieving 69.77%-100.00% versus SCART's 43.6%-99.5%. The 20% dose level coverage for gross target volume (GTV) is slightly lower for pSCART, achieving 88.96%-98.64% versus SCART's 90.1%-99.9%. The maximum point dose outside the target volume is lower for pSCART at 4.58-6.19 Gy versus SCART's 4.78-6.67 Gy; additionally, the V5Gy at the tumor edge is significantly smaller for pSCART at 5.93-23.72 cm3 versus SCART's 6.85-151.66 cm3. The average dose to most OARs in the pSCART plan is lower than in the SCART plan.

Conclusions

This work provides initial insights into evaluating treatment plans for bulky tumors using pSCART. Compared to the CyberKnife SCART, pSCART generates significantly higher prescription doses and larger high-dose regions within the GTV while delivering lower doses at the tumor edge, enhancing normal tissue sparing.

Synergistic effects of thermosensitive liposomal doxorubicin, mild hyperthermia, and radiotherapy in breast cancer management: an orthotopic mouse model study

Liposome formulations of the cancer drug doxorubicin have been developed to address the severe side effects that result from administration of this drug in a conventional formulation. Among them, thermosensitive liposomal doxorubicin presents enhanced tumor targeting and efficient drug release when combined with mild hyperthermia localized to the tumor site. Exploiting the radiosensitizing benefits of localized thermal therapy, the integration of radiation therapy with the thermally activated liposomal system is posited to amplify the anti-tumor efficacy. This study explored a synergistic therapeutic strategy that combines thermosensitive liposomal doxorubicin, mild hyperthermia, and radiotherapy, using an orthotopic murine model of breast cancer. The protocol of sequential multi-modal treatment, incorporating low-dose chemotherapy and radiotherapy, substantially postponed the progression of primary tumor growth in comparison to the application of monotherapy at elevated dosages. Improvements in unheated distant lesions were also observed. Furthermore, the toxicity associated with the combination treatment was comparable to that of either thermosensitive liposome treatment or radiation alone at low doses. These outcomes underscore the potential of multi-modal therapeutic strategies to refine treatment efficacy while concurrently diminishing adverse effects in the management of breast cancer, providing valuable insight for the future refinement of thermosensitive liposomal doxorubicin applications.

The abscopal effects of sonodynamic therapy in cancer

The abscopal effect is a phenomenon wherein localised therapy on the primary tumour leads to regression of distal metastatic growths. Interestingly, various pre-clinical studies utilising sonodynamic therapy (SDT) have reported significant abscopal effects, however, the mechanism remains largely enigmatic. SDT is an emerging non-invasive cancer treatment that uses focussed ultrasound (FUS) and a sonosensitiser to induce tumour cell death. To expand our understanding of abscopal effects of SDT, we have summarised the preclinical studies that have found SDT-induced abscopal responses across various cancer models, using diverse combination strategies with nanomaterials, microbubbles, chemotherapy, and immune checkpoint inhibitors. Additionally, we shed light on the molecular and immunological mechanisms underpinning SDT-induced primary and metastatic tumour cell death, as well as the role and efficacy of different sonosensitisers. Notably, the observed abscopal effects underscore the need for continued investigation into the SDT-induced 'vaccine-effect' as a potential strategy for enhancing systemic anti-tumour immunity and combating metastatic disease. The results of the first SDT human clinical trials are much awaited and are hoped to enable the further evaluation of the safety and efficacy of SDT, paving the way for future studies specifically designed to explore the potential of translating SDT-induced abscopal effects into clinical reality.

Preventive effects of low-dose radiation and hypofractionated radiation plus anti-programmed cell death protein 1 on lung metastasis in breast cancer

Background

Previous experiments have demonstrated that hypofractionated radiation therapy (HFRT), low-dose radiation therapy (LDRT), and combined anti-programmed cell death protein 1 (αPD-1) can enhance the abscopal effect. Combined with the phenomenon of low prognosis in patients with breast cancer lung metastasis, our study establishes a mouse model and changes the irradiation regimen of LDRT to explore its preventive effect on breast cancer lung metastasis.

Methods

The breast cancer subcutaneous graft tumor model was developed. Two-lung prophylactic LDRT was performed prior to the onset of lung metastases, in combination with HFRT (8 Gy, 3f), and αPD-1 (200 μg, 4f) therapy. We watched and documented the tumor volume, survival duration, and number of lung metastases. Furthermore, after labeling the corresponding cells using markers, we detected immune-related cell infiltration by immunohistochemistry and flow cytometry, such as T cells. We also determined the expression of cytokines (IFN-γ and TNF-α) by enzyme-linked immunosorbent assay.

Result

The triple therapy (HFRT+LDRT+αPD-1) resulted in tumor shrinkage and prolonged survival in mice, with median survival extending from 35 to 52 days. The most notable decrease in the quantity of advanced lung metastatic nodules in breast cancer was observed with the triple therapy (HFRT+LDRT+αPD-1) (p < 0.05). Furthermore, according to immunohistochemistry and flow cytometry, the triple treatment (HFRT+LDRT+αPD-1) showed the greatest expression of CD8+ T cells. Additionally, the ratio of CD8+/CD4+ T cells was considerably greater than that of the groups (p < 0.0001). Triple therapy (HFRT+LDRT+αPD-1) increased the recruitment of DCs cells, promoted IFN-γ and TNF-α expression, and curbed the aggregation of MDSCs cells (p < 0.05).

Conclusion

Prophylactic LDRT to the lungs, based on HFRT and αPD-1, can enhance anti-tumor efficacy and prevent advanced lung metastases from breast cancer. The process involves boosting the recruitment of DCs and CD8+ T cells, preventing MDSC cell aggregation, and lessening the tumor microenvironment's immunosuppressive effects.

Feasibility study of synchronously increasing dose of multi-shell structure to improve stereotactic ablation radiotherapy central dose of large volume locally advanced gastrointestinal stromal tumors using cyberKnife

Purpose. Increasing the central dose for large, locally advanced, drug-resistant gastrointestinal stromal tumors (LADR-GISTs) has consistently been a significant challenge. This study explores the feasibility of using multiple shell structures within the tumor to enhance the central ablation dose of large LADR-GIST by increasing the shell doses.Methods and Materials. This study involved five patients with large LADR-GIST who were treated with CyberKnife. The gross tumor volume (GTV) was delineated as a multi-shell structure. Five dose escalation plans (SIB-SBRT) were created for each patient, varying the dose escalation ratios. The radiation doses for the center of the GTV (GTV center) in these plans ranged from 49 Gy to 70 Gy. Parameter evaluations were conducted comparing the SIB-SBRT plans with conventional SBRT plans (Con-SBRT), focusing on equivalent uniform dose (EUD), relative equivalent uniform dose (rEUD), dose volume parameters, conformal index (CI), new conformal index (nCI), gradient index (GI), and monitor unit (MU). The Friedman Test was employed to determine statistical differences (P< 0.05), followed by pairwise comparisons.Results. When the dose escalation ratios reached 25% of the prescribed dose, the average rEUD increased to 6.92, and the proportion of the GTV volume with Biologically Equivalent Dose (BED)> 100 Gy increased to 30.69%. At dose escalation ratios of 30% of the prescribed dose, the rEUD stabilized, but the radiation dose received by the bladder, colon, and duodenum significantly increased. Except for the SIB25-SBRT and SIB30-SBRT groups, no statistically significant differences were observed between the other SIB-SBRT groups and the Con-SBRT group across various evaluation metrics.Conclusions. The method of synchronously increasing the dose using a multi-shell structure is feasible for stereotactic ablation in the treatment of LADR-GISTs using CyberKnife. The results indicate that dose escalation ratios of 25% of the prescribed dose can provide a satisfactory ablation dose (BED > 100 Gy), covering 31% of the large tumor volume.

The efficacy and safety of induction chemotherapy combined with sintilimab followed by concurrent chemoradiotherapy plus sintilimab sequencing maintaining with sintilimab for patients with unresectable locally advanced esophageal squamous cell carcinoma

PURPOSE

To evaluate the efficacy and safety of induction chemotherapy combined with programmed death protein 1 (PD-1) inhibitor (sintilimab) followed by concurrent chemoradiotherapy (CCRT) plus sintilimab, and subsequent maintenance with sintilimab (IC-ICCRT-IO) for patients with unresectable locally advanced esophageal squamous cell carcinoma (ESCC) in a retrospective study.

METHODS

Data from patients with histologically confirmed, locally advanced, inoperable ESCC who received IC-ICCRT-IO were retrospectively analyzed. Treatment effects were evaluated after 2 cycles of induction therapy and after CCRT by contrast-enhanced CT scans and esophagograms, followed by subsequent evaluations every 3 months post-treatment. The primary endpoints included progression-free survival (PFS) and PFS rates at 6, 12, and 18 months. Secondary endpoints involved overall response rate (ORR), disease control rate (DCR), overall survival (OS), and safety. The influence of the expression level of programmed death ligand-1 (PD-L1) as well as neutrophil-to-lymphocyte ratio (NLR) on efficacy of the IC-ICCRT-IO was analyzed.

RESULTS

In total, 29 eligible patients were enrolled and analyzed. The median follow-up time was 20.5 months. The median PFS was not reached; the 6-, 12-, and 18-month PFS rates were 100.0%, 93.1%, and 82.8%, respectively. The median OS was not reached, and the 6-, 12-, and 18-month OS rates were all 100.0%. The ORR and DCR were 89.7% and 100.0%. Adverse events (AEs) were manageable, with grade 3 or higher AEs observed in 48.2% of patients, primarily nonimmune-related and clinically manageable. Hematologic toxicity was predominant. Two patients developed grade 3 immune-related rash, and two patients developed grade 3 radiation pneumonitis, all of whom were managed with appropriate symptomatic treatment. No significant differences in survival outcomes were observed with respect to PD-L1 and NLR.

CONCLUSION

Our results indicated that the IC-ICCRT-IO regimen for unresectable locally advanced ESCC provided a survival benefit with manageable safety profile. More prospective clinical studies should be warranted.

TRIAL REGISTRATION

2024-04-22, No. QYFY WZLL 28,684, retrospectively registered.

Spontaneous regression in mature T-cell non-Hodgkin lymphoma

INTRODUCTION

Spontaneous regression (SR) is observed in some patients with mature T-cell non-Hodgkin lymphoma (MTCL), including adult T-cell leukemia/lymphoma (ATL), although the incidence is rare.

AREA COVERED

We extracted 31 cases with MTCL who experienced SR based on a literature search and summarized the patient characteristics and clinical outcomes.

EXPERT OPINION

MTCL with SR included various subtypes, the most common being ATL (n = 17). Five of 24 cases (21%) maintained SR for more than 5 years, and the median duration of SR was 2 years. Sixteen of 31 cases (52%) experienced tumor relapse after SR. Two retrospective studies including ATL cases showed SR rates of 18% and 4%, respectively. Representative triggers are infection and surgical biopsies, and possible mechanisms include immunological mechanisms such as cross-reactivity of virus-specific T cells with tumor antigens. The diagnostic criteria for SR are not standardized among reports, and the clinical outcomes are not fully described. Practically, observation is the only accepted strategy after SR was achieved. In the era of molecular targeted therapy or immunotherapy, new strategies including maintenance therapy after SR could be discussed, although clinical data are lacking.

Shifting cold to hot tumors by nanoparticle-loaded drugs and products

Cold tumors lack antitumor immunity and are resistant to therapy, representing a major challenge in cancer medicine. Because of the immunosuppressive spirit of the tumor microenvironment (TME), this form of tumor has a low response to immunotherapy, radiotherapy, and also chemotherapy. Cold tumors have low infiltration of immune cells and a high expression of co-inhibitory molecules, such as immune checkpoints and immunosuppressive molecules. Therefore, targeting TME and remodeling immunity in cold tumors can improve the chance of tumor repression after therapy. However, tumor stroma prevents the infiltration of inflammatory cells and hinders the penetration of diverse molecules and drugs. Nanoparticles are an intriguing tool for the delivery of immune modulatory agents and shifting cold to hot tumors. In this review article, we discuss the mechanisms underlying the ability of nanoparticles loaded with different drugs and products to modulate TME and enhance immune cell infiltration. We also focus on newest progresses in the design and development of nanoparticle-based strategies for changing cold to hot tumors. These include the use of nanoparticles for targeted delivery of immunomodulatory agents, such as cytokines, small molecules, and checkpoint inhibitors, and for co-delivery of chemotherapy drugs and immunomodulatory agents. Furthermore, we discuss the potential of nanoparticles for enhancing the efficacy of cancer vaccines and cell therapy for overcoming resistance to treatment.

Efficacy and Mechanism of Combining Radiotherapy and Immunotherapy in Stage IV Non-Small Cell Lung Cancer

OPINION STATEMENT

Lung cancer is the leading cause of cancer-related deaths worldwide, with about 85% of patients being diagnosed as non-small cell lung cancer (NSCLC); and most presenting with stage IV disease initially. With the continuous advancement of treatment strategies of oncology, immunotherapy with/without chemo-immunotherapy has become the first-line treatment for patients with stage IV NSCLC. However, a proportion of patients still develop resistance to the treatment regimen and experience local progression, and primary lung lesion progression is the main progression pattern of stage IV NSCLC. Preclinical and clinical studies have demonstrated the potential of radiotherapy in anti-tumor treatment and suggest that administering local radiotherapy prior to cancer progression can prolong survival. Therefore, we consider whether adding local radiotherapy before the progression of a pulmonary lesion in stage IV NSCLC patients receiving chemo-immunotherapy would be beneficial. The present review aims to explore the efficacy and safety of combining radiotherapy with immunotherapy in the treatment of stage IV NSCLC, delving into the intricacies of their underlying mechanism.

Systemic tumor regression with synergy therapy: radiotherapy and CAR-T

Pancreatic ductal adenocarcinoma (PDAC) is one of the most poorly prognostic digestive tract malignancies. CLDN18.2 CAR-T therapy has recently shown promising clinical effects in PDAC. Radiotherapy, a traditional treatment, can induce systemic immune activation and abscopal effects. However, the synergistic effect and mechanism of their combination in PDAC treatment remain poorly understood. In this study, we developed a CLDN18.2-specific CAR-T and applied it to unilateral and bilateral mouse tumor models. Our results demonstrated that this synergy therapy not only improved tumor-killing effects in unilateral tumor-bearing mice but also induced regression in both local and distant tumors in bilateral tumor models. Mechanistically, early radiation-induced apoptosis promoted the proliferation of CD8 + T cells, while increased chemokine CCL2 levels from localized and distant tumor sites facilitated CAR-T and endogenous T cell infiltration, leading to systemic tumor suppression. This study proposes a promising approach for treating metastatic pancreatic cancer by combining radiotherapy and CAR-T therapy, elucidating the mechanism of CAR-T cell-enhanced radiotherapy effects ex vivo, and highlighting a novel strategy for combating metastatic pancreatic cancer.

Immunogenicity of radiotherapy on bone metastases from prostate adenocarcinoma: What is the future for the combination with radiotherapy/immunotherapy?

Bone metastatic prostate cancers (PCa) are resistant to usual immunotherapies such as checkpoint inhibitors. The main hypothesis related to this immunoresistance is the lack of antigens to stimulate anti-tumor immunity. External radiation is a potential inducer antigens presentation and thus to immunotherapy proprieties. The aim of this review is to describe the tumor microenvironment specificities, especially in bone metastasis and the immune modifications after radiation therapy on a metastatic castration-resistant PCa population. PCa microenvironment is immunosuppressive because of many tumor factors. The complex interplay between PCa cells and bone microenvironment leads to a 'vicious circle' promoting bone metastasis. Furthermore, the immune and bone systems, are connected through an osteoclastogenic cytokine: the Receptor Activator Nuclear Factor Kappa B ligand. Adapted doses of ionizing radiation play a dual role on the tumor. Indeed, radiotherapy leads to immunogenicity by inducing damage associated with molecular patterns. However, it also induces an immunosuppressive effect by increasing the number of immunosuppressive cells. Interestingly, the abscopal effect could be used to optimize immunotherapy potential, especially on bone metastasis. Radiotherapy and immunotherapy combination is a promising strategy, however further studies are necessary to determine the more efficient types of radiation and to control the abscopal effect.

Enhancing in situ cancer vaccines using delivery technologies

In situ cancer vaccination refers to any approach that exploits tumour antigens available at a tumour site to induce tumour-specific adaptive immune responses. These approaches hold great promise for the treatment of many solid tumours, with numerous candidate drugs under preclinical or clinical evaluation and several products already approved. However, there are challenges in the development of effective in situ cancer vaccines. For example, inadequate release of tumour antigens from tumour cells limits antigen uptake by immune cells; insufficient antigen processing by antigen-presenting cells restricts the generation of antigen-specific T cell responses; and the suppressive immune microenvironment of the tumour leads to exhaustion and death of effector cells. Rationally designed delivery technologies such as lipid nanoparticles, hydrogels, scaffolds and polymeric nanoparticles are uniquely suited to overcome these challenges through the targeted delivery of therapeutics to tumour cells, immune cells or the extracellular matrix. Here, we discuss delivery technologies that have the potential to reduce various clinical barriers for in situ cancer vaccines. We also provide our perspective on this emerging field that lies at the interface of cancer vaccine biology and delivery technologies.

Integrative Approaches in Non-Small Cell Lung Cancer Management: The Role of Radiotherapy

Treatment guidelines for non-small cell lung cancer (NSCLC) vary by several factors including pathological stage, patient candidacy, and goal of treatment. With many therapeutics and even more combinations available in the NSCLC clinician's toolkit, a multitude of questions remain unanswered vis-a-vis treatment optimization. While some studies have begun exploring the interplay among the many pillars of NSCLC treatment-surgical resection, radiotherapy, chemotherapy, and immunotherapy-the vast number of combinations and permutations of different therapy modalities in addition to the modulation of each constituent therapy leaves much to be desired in a field that is otherwise rapidly evolving. Given NSCLC's high incidence and lethality, the experimentation of synergistic benefits that combinatorial treatment may confer presents a ripe target for advancement and increased understanding without the cost and burden of novel drug development. This review introduces, synthesizes, and compares prominent NSCLC therapies, placing emphasis on the interplay among types of therapies and the synergistic benefits some combinatorial therapies have demonstrated over the past several years.

A future directions of renal cell carcinoma treatment: combination of immune checkpoint inhibition and carbon ion radiotherapy

Renal cell carcinoma (RCC) is considered radio- and chemo-resistant. Immune checkpoint inhibitors (ICIs) have demonstrated significant clinical efficacy in advanced RCC. However, the overall response rate of RCC to monotherapy remains limited. Given its immunomodulatory effects, a combination of radiotherapy (RT) with immunotherapy is increasingly used for cancer treatment. Heavy ion radiotherapy, specifically the carbon ion radiotherapy (CIRT), represents an innovative approach to cancer treatment, offering superior physical and biological effectiveness compared to conventional photon radiotherapy and exhibiting obvious advantages in cancer treatment. The combination of CIRT and immunotherapy showed robust effectiveness in preclinical studies of various tumors, thus holds promise for overcoming radiation resistance of RCC and enhancing therapeutic outcomes. Here, we provide a comprehensive review on the biophysical effects of CIRT, the efficacy of combination treatment and the underlying mechanisms involved in, as well as its therapeutic potential specifically within RCC.

Immunohistochemical Profiling of SSTR2 and HIF-2α with the Tumor Microenvironment in Pheochromocytoma and Paraganglioma

Metastatic pheochromocytomas and paragangliomas (PPGLs) are rare endocrine malignancies with limited effective treatment options. The association between the tumor microenvironment (TME) with somatostatin receptor 2 (SSTR2) and hypoxia-induced factor-2α (HIF-2α) in PPGLs, critical for optimizing combination therapeutic strategies with immunotherapy, remains largely unexplored. To evaluate the association of SSTR2 and HIF-2α immunoreactivity with the TME in patients with PPGLs, we analyzed the expression of SSTR2A, HIF-2α, and TME components, including tumor-infiltrating lymphocytes (CD4 and CD8), tumor-associated macrophages (CD68 and CD163), and PD-L1, using immunohistochemistry in patients with PPGLs. The primary outcome was to determine the association of the immune profiles with SSTR2A and HIF-2α expression. Among 45 patients with PPGLs, SSTR2A and HIF2α were positively expressed in 21 (46.7%) and 14 (31.1%) patients, respectively. The median PD-L1 immunohistochemical score (IHS) was 2.0 (interquartile range: 0-30.0). Positive correlations were observed between CD4, CD8, CD68, and CD163 levels. A negative correlation was found between the CD163/CD68 ratio (an indicator of M2 polarization) and SSTR2A expression (r = -0.385, p = 0.006). HIF-2α expression showed a positive correlation with PD-L1 IHS (r = 0.348, p = 0.013). The co-expression of PD-L1 (HIS > 10) and HIF-2α was found in seven patients (15.6%). No associations were observed between SDHB staining results and the CD163/CD68 ratio, PD-L1, or SSTR2A expression. Our data suggest the potential of combination therapy with immunotherapy and peptide receptor radionuclide therapy or HIF-2α inhibitors as a treatment option in selected PPGL populations.

Non-targeted effects of radiation therapy for glioblastoma

Radiotherapy is recommended for the treatment of brain tumors such as glioblastoma (GBM) and brain metastases. Various curative and palliative scenarios suggest improved local-regional control. Although the underlying mechanisms are not yet clear, additional therapeutic effects have been described, including proximity and abscopal reactions at the treatment site. Clinical and preclinical data suggest that the immune system plays an essential role in regulating the non-targeted effects of radiotherapy for GBM. This article reviews current biological mechanisms for regulating the non-targeted effects caused by external and internal radiotherapy, and how they might be applied in a clinical context. Optimization of therapeutic regimens requires assessment of the complexity of the host immune system on the activity of immunosuppressive or immunostimulatory cells, such as glioma-associated macrophages and microglia. This article also discusses recent preclinical models adapted to post-radiotherapy responses. This narrative review explores and discusses the current status of immune responses both locally via the "bystander effect" and remotely via the "abscopal effect". Preclinical and clinical observations demonstrate that unirradiated cells, near or far from the irradiation site, can control the tumor response. Nevertheless, previous studies do not address the problem in its global context, and present gaps regarding the link between the role of the immune system in the control of non-targeted effects for different types of radiotherapy and different fractionation schemes applied to GBM. This narrative synthesis of the scientific literature should help to update and critique available preclinical and medical knowledge. Indirectly, it will help formulate new research projects based on the synthesis and interpretation of results from a non-systematic selection of published studies.

Stereotactic central/core ablative radiation therapy: results of a phase I study of a novel strategy to treat bulky tumor

Purpose

Bulky tumor remains as a challenge to surgery, chemotherapy and conventional radiation therapy. Hence, in efforts to overcome this challenge, we designed a novel therapeutic paradigm via strategy of Stereotactic Central/Core Ablative Radiation Therapy (SCART).), which is based on the principles of SBRT (stereotactic body radiation therapy and spatially fractionated radiation therapy (SFRT). We intend to safely deliver an ablative dose to the core of the tumor and with a low dose at tumor edge. The purpose of the phase 1 study was to determine dose-limiting toxicities (DLT)s and the Maximum Tolerated Dose (MTD) of SCART.

Methods and materials

We defined a SCART-plan volume inside the tumor, which is proportional to the dimension of tumor. VMAT/Cyberknife technique was adopted. In the current clinical trial; Patients with biopsy proven recurrent or metastatic bulky cancers were enrolled. The five dose levels were 15 Gy X1, 15Gy X3, 18GyX3, 21GyX3 and 24GyX3, while keeping the whole tumor GTV's border dose at 5Gy each fraction. There was no restriction on concurrent systemic chemotherapy agents.

Results

21 patients were enrolled and underwent SCART. All 21 patients have eligible data for study follow-up. Radiotherapy was well tolerated with all treatment completed as scheduled. The dose was escalated for two patients to 24GyX3. No grade 3 or higher toxicity was observed in any of the enrolled patients. The average age of patients was 66 years (range: 14-85) and 13 (62%) patients were male. The median SCART dose was 18Gy (range: 15 - 24). Six out of the 18 patients with data for overall survival (OS) died, and the median time to death was 16.3 months (range: 1 - 25.6). The mean percent change for tumor shrinkage between first visit volumes and post-SCART volumes was 49.5% (SD: 40.89, p-value:0.009).

Conclusion

SCART was safely escalated to 24 GyX 3 fractions, which is the maximum Tolerated Dose (MTD) for SCART. This regimen will be used in future phase II trials.

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.

SBRT for Liver Tumors: What the Interventional Radiologist Needs to Know

This review summarizes the clinical evidence supporting the utilization of stereotactic body radiotherapy (SBRT) for liver tumors, including hepatocellular carcinoma, liver metastases, and cholangiocarcinoma. Emerging prospective evidence has demonstrated the benefit and low rates of toxicity across a broad range of clinical contexts. We provide an introduction for the interventional radiologist, with a discussion of underlying themes such as tumor dose-response, mitigation of liver toxicity, and the technical considerations relevant to performing liver SBRT. Ultimately, we recommend that SBRT should be routinely included in the armamentarium of locoregional therapies for liver malignancies, alongside those liver-directed therapies offered by interventional radiology.

Hepatocellular Carcinoma Showing Tumor Shrinkage Due to an Abscopal Effect

We herein report a 63-year-old man who presented with left lower jaw pain and was diagnosed with hepatocellular carcinoma with bone metastases post-examination. All tumors grew after immunotherapy with atezolizumab and bevacizumab, and his jaw pain worsened. After palliative radiation therapy, however, the tumors shrank markedly, with no recurrence seen after stopping immunotherapy. To our knowledge, this is the first case in which a radiotherapy- and immunotherapy-mediated abscopal effect facilitated tumor shrinkage and immunotherapy discontinuation.

Nanotechnology-enhanced radiotherapy and the abscopal effect: Current status and challenges of nanomaterial-based radio-immunotherapy

Rare but consistent reports of abscopal remission in patients challenge the notion that radiotherapy (RT) is a local treatment; radiation-induced cancer cell death can trigger activation and recruitment of dendritic cells to the primary tumor site, which subsequently initiates systemic immune responses against metastatic lesions. Although this abscopal effect was initially considered an anomaly, combining RT with immune checkpoint inhibitor therapies has been shown to greatly improve the incidence of abscopal responses via modulation of the immunosuppressive tumor microenvironment. Preclinical studies have demonstrated that nanomaterials can further improve the reliability and potency of the abscopal effect for various different types of cancer by (1) altering the cell death process to be more immunogenic, (2) facilitating the capture and transfer of tumor antigens from the site of cancer cell death to antigen-presenting cells, and (3) co-delivering immune checkpoint inhibitors along with radio-enhancing agents. Several unanswered questions remain concerning the exact mechanisms of action for nanomaterial-enhanced RT and for its combination with immune checkpoint inhibition and other immunostimulatory treatments in clinically relevant settings. The purpose of this article is to summarize key recent developments in this field and also highlight knowledge gaps that exist in this field. An improved mechanistic understanding will be critical for clinical translation of nanomaterials for advanced radio-immunotherapy. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Activation of STING in Response to Partial-Tumor Radiation Exposure

PURPOSE

To determine the mechanisms involved in partial volume radiation therapy (RT)-induced tumor response.

METHODS AND MATERIALS

We investigated 67NR murine orthotopic breast tumors in Balb/c mice and Lewis lung carcinoma (LLC cells; WT, Crispr/Cas9 Sting KO, and Atm KO) injected in the flank of C57Bl/6, cGAS, or STING KO mice. RT was delivered to 50% or 100% of the tumor volume using a 2 × 2 cm collimator on a microirradiator allowing precise irradiation. Tumors and blood were collected at 6, 24, and 48 hours post-RT and assessed for cytokine measurements.

RESULTS

There is a significant activation of the cGAS/STING pathway in the hemi-irradiated tumors compared with control and to 100% exposed 67NR tumors. In the LLC model, we determined that an ATM-mediated noncanonical activation of STING is involved. We demonstrated that the partial exposure RT-mediated immune response is dependent on ATM activation in the tumor cells and on the STING activation in the host, and cGAS is dispensable. Our results also indicate that partial volume RT stimulates a proinflammatory cytokine response compared with the anti-inflammatory profile induced by 100% tumor volume exposure.

CONCLUSIONS

Partial volume RT induces an antitumor response by activating STING, which stimulates a specific cytokine signature as part of the immune response. However, the mechanism of this STING activation, via the canonical cGAS/STING pathway or a noncanonical ATM-driven pathway, depends on the tumor type. Identifying the upstream pathways responsible for STING activation in the partial RT-mediated immune response in different tumor types would improve this therapy and its potential combination with immune checkpoint blockade and other antitumor therapies.

Radiotherapy, photodynamic therapy, and cryoablation-induced abscopal effect: Challenges and future prospects

Local therapy modalities such as radiation therapy, photodynamic therapy, photothermal therapy, and cryoablation have been used to treat localized tumors for decades. The discovery of the abscopal effect causes a paradigm shift where local therapy also causes systemic effects and leads to the remission of nonirradiated tumors. The abscopal effect of radiation therapy, alone or in combination with other treatments, has been extensively studied over the last six decades. However, the results are unsatisfactory in producing robust, reproducible, and long-lasting systemic effects. Although immunotherapy and radiation therapy are promising in producing the abscopal effect, the abscopal effect's mechanism is still unclear, owing to various factors such as irradiation type and dose and cancer type. This article reviews the research progress, clinical and preclinical evidence of the abscopal effect by various local therapies alone and in combination with chemotherapy and immunotherapy, case reports, and the current challenges in producing the abscopal effect by various local therapies, focusing on radiotherapy, photodynamic therapy, cryoablation, and the prospects for obtaining a robust, reproducible, and long-lasting abscopal effect.

Enhanced systemic tumor suppression by in situ vaccine combining radiation and OX40 agonist with CpG therapy

BACKGROUND

In situ tumor vaccine has been gradually becoming a hot research field for its advantage of achieving personalized tumor therapy without prior antigen identification. Various in situ tumor vaccine regimens have been reported to exert considerable antitumor efficacy in preclinical and clinical studies. However, the design of in situ tumor vaccines still needs further optimization and the underlying immune mechanism also waits for deeper investigation.

METHODS

A novel triple in situ vaccine strategy that combining local radiation with intratumoral injection of TLR9 agonist CpG and OX40 agonist was established in this sturdy. Local and abscopal antitumor efficacy as well as survival benefit were evaluated in the bilateral tumors and pulmonary metastasis model of B16F10 melanoma. In situ vaccine-induced immune responses and immune-associated variation in tumor environment were further investigated using multiparameter flow cytometry and RNA sequencing. Base on the analysis, the RT + CpG + αOX40 triple in situ vaccine was combined with checkpoint blockade therapy to explore the potential synergistic antitumor efficacy.

RESULTS

Enhanced tumor suppression was observed with minimal toxicity in both treated and untreated abscopal tumors after receiving RT + CpG + αOX40 triple vaccine. The introduction of local radiation and OX40 agonist benefit more to the inhibition of local and abscopal lesions respectively, which might be partially attributed to the increase of effector memory T cells in the tumor microenvironment. Further analysis implied that the triple in situ vaccine did not only activate the microenvironment of treated tumors, with the upregulation of multiple immune-associated pathways, but also enhanced systemic antitumor responses, thus achieved superior systemic tumor control and survival benefit. Moreover, the triple in situ vaccine synergized with checkpoint blockade therapy, and significantly improved the therapeutic effect of anti-programmed cell death protein (PD)-1 antibody.

CONCLUSION

This triple combining in situ vaccine induced intensive antitumor responses, mediated effective systemic tumor control and survival benefit, and displayed impressive synergistic antitumor effect with checkpoint blockade therapy. These data preliminary confirmed the efficacy, feasibility and safety of the triple combining in situ vaccine, suggesting its great application potential as both monotherapy and a part of combined immunotherapeutic regimens in clinical scenario.

The abscopal effect of anti-CD95 and radiotherapy in melanoma

BACKGROUND

Radiotherapy (RT) is frequently adopted to control cancer cell proliferation, which is achieved by altering the tumor microenvironment (TME) and immunogenicity. Apoptosis of cancer cells is the major effect of radiation on tumor tissues. Fas/APO-1(CD95) receptors on the cell membrane are death receptors that can be activated by diverse factors, including radiation and integration with CD95L on CD8⁺ T cells. The abscopal effect is defined as tumor regression out of the local RT field, and it is produced through anti-tumor immunity. The immune response against the radiated tumor is characterized by the cross-presentation between antigen-presenting cells (APCs), which includes cytotoxic T cells (CTLs) and dendritic cells (DCs).

METHODS

The effect of activation and radiation of CD95 receptors on melanoma cell lines was examined in vivo and in vitro. In vivo, bilateral lower limbs were given a subcutaneous injection of a dual-tumor. Tumors in the right limb were radiated with a single dose of 10 Gy (primary tumor), while tumors in the left limb (secondary tumor) were spared.

RESULTS

The anti-CD95 treatment plus radiation (combination treatment) reduced growth rates of both primary and secondary tumors relative to the control or radiation groups. In addition, higher degrees of infiltrating CTLs and DCs were detected in the combination treatment compared to the other groups, but the immune response responsible for secondary tumor rejection was not proven to be tumor specific. In vitro, combination treatment combined with radiation resulted in further apoptosis of melanoma cells relative to controls or cells treated with radiation.

CONCLUSIONS

Targeting CD95 on cancer cells will induce tumor control and the abscopal effect.

The abscopal effect in patients with cancer receiving immunotherapy

Interest in the abscopal effect has been rekindled over the past decade with the advent of immunotherapy. Although purportedly elusive, this phenomenon is being increasingly reported. Venturing further using a multimodality approach with an array of systemic agents and unconventional modalities is direly needed. In this perspective, we describe the fundamentals of abscopal responses (ARs), explore combinations with systemic therapies that hold promise in eliciting ARs, and reconnoiter unconventional modalities that may induce ARs. Finally, we scrutinize prospective agents and modalities that exhibit preclinical ability to elicit ARs and discuss prognostic biomarkers, their limitations, and pathways of abscopal resistance for reproducibility.

Harnessing immunotherapy to enhance the systemic anti-tumor effects of thermosensitive liposomes

Chemotherapy plays an important role in debulking tumors in advance of surgery and/or radiotherapy, tackling residual disease, and treating metastatic disease. In recent years many promising advanced drug delivery strategies have emerged that offer more targeted delivery approaches to chemotherapy treatment. For example, thermosensitive liposome-mediated drug delivery in combination with localized mild hyperthermia can increase local drug concentrations resulting in a reduction in systemic toxicity and an improvement in local disease control. However, the majority of solid tumor-associated deaths are due to metastatic spread. A therapeutic approach focused on a localized target area harbors the risk of overlooking and undertreating potential metastatic spread. Previous studies reported systemic, albeit limited, anti-tumor effects following treatment with thermosensitive liposomal chemotherapy and localized mild hyperthermia. This work explores the systemic treatment capabilities of a thermosensitive liposome formulation of the vinca alkaloid vinorelbine in combination with mild hyperthermia in an immunocompetent murine model of rhabdomyosarcoma. This treatment approach was found to be highly effective at heated, primary tumor sites. However, it demonstrated limited anti-tumor effects in secondary, distant tumors. As a result, the addition of immune checkpoint inhibition therapy was pursued to further enhance the systemic anti-tumor effect of this treatment approach. Once combined with immune checkpoint inhibition therapy, a significant improvement in systemic treatment capability was achieved. We believe this is one of the first studies to demonstrate that a triple combination of thermosensitive liposomes, localized mild hyperthermia, and immune checkpoint inhibition therapy can enhance the systemic treatment capabilities of thermosensitive liposomes.

Combined Loco-Regional and Systemic Treatment Strategies for Hepatocellular Carcinoma: From Basics to New Developments

Recent advances in systemic therapeutic options have led to improved survival in patients with advanced hepatocellular carcinoma. In order to optimize patient outcomes across different disease stages, attempts are being made at exploiting combinations of loco-regional treatments and systemic therapeutic regimens. The possibilities of a beneficial synergistic effect are strongly supported by biological evidence of changes in tumor microenvironment and systemic immunity. With the advent of newer interventional technologies and newer biological and immunological drugs, these possibilities keep on gaining interest and expectations, yet many questions remain unanswered as to how to best manipulate and combine the two therapeutic approaches.This review aims at providing a general overview of biological foundations, preliminary clinical applications, critical issues and future directions of this constantly growing field.

125I Radiotherapy combined with metronomic chemotherapy may boost the abscopal effect, leading to complete regression of liver metastasis in an SCLC patient with a 58.5-month OS: a case report

The liver is the most common and lethal metastatic site in patients with extensive-stage small-cell lung cancer (ES-SCLC), and median survival with current standard treatment is only 9-10 months from diagnosis. Clinical observations show that a complete response (CR) is extremely rare in ES-SCLC patients with liver metastasis. Moreover, to the best of our knowledge, complete regression of liver metastasis induced by the abscopal effect, boosted primarily by permanent radioactive iodine-125 seeds implantation (PRISI), combined with a low-dose metronomic temozolomide (TMZ) regimen, has not been recorded. Here, we present the case of a 54-year-old male patient who developed multiple liver metastases from ES-SCLC after multiple lines of chemotherapy. The patient was given partial PRISI therapy (two out of six tumor lesions; 38 iodine-125 seeds in one dorsal lesion and 26 seeds in one ventral lesion), which was combined with TMZ metronomic chemotherapy (50 mg/m²/day, days 1-21, every 28 days). The abscopal effect was observed for 1 month after PRISI treatment. After about 1 year, all the liver metastases had completely disappeared, and the patient experienced no relapse. The patient eventually died of malnutrition caused by a non-tumor intestinal obstruction and had an overall survival of 58.5 months after diagnosis. PRISI combined with TMZ metronomic chemotherapy might be considered a potential therapy to trigger the abscopal effect in patients with liver metastases.

Ecological niches for colorectal cancer stem cell survival and thrival

To date, colorectal cancer is still ranking top three cancer types severely threatening lives. According to cancer stem cell hypothesis, malignant colorectal lumps are cultivated by a set of abnormal epithelial cells with stem cell-like characteristics. These vicious stem cells are derived from intestinal epithelial stem cells or transformed by terminally differentiated epithelial cells when they accumulate an array of transforming genomic alterations. Colorectal cancer stem cells, whatever cell-of-origin, give rise to all morphologically and functionally heterogenous tumor daughter cells, conferring them with overwhelming resilience to intrinsic and extrinsic stresses. On the other hand, colorectal cancer stem cells and their daughter cells continuously participate in constructing ecological niches for their survival and thrival by communicating with adjacent stromal cells and circulating immune guardians. In this review, we first provide an overview of the normal cell-of-origin populations contributing to colorectal cancer stem cell reservoirs and the niche architecture which cancer stem cells depend on at early stage. Then we survey recent advances on how these aberrant niches are fostered by cancer stem cells and their neighbors. We also discuss recent research on how niche microenvironment affects colorectal cancer stem cell behaviors such as plasticity, metabolism, escape of immune surveillance as well as resistance to clinical therapies, therefore endowing them with competitive advantages compared to their normal partners. In the end, we explore therapeutic strategies available to target malignant stem cells.

Neoadjuvant immunotherapy for resectable esophageal cancer: A review

Esophageal cancer (EC) is one of the most common cancers worldwide, especially in China. Despite therapeutic advances, the 5-year survival rate of EC is still dismal. For patients with resectable disease, neoadjuvant chemoradiotherapy (nCRT) in combination with esophagectomy is the mainstay of treatment. However, the pathological complete response (pCR) rate to nCRT of 29.2% to 43.2% is not satisfactory, and approximately half of the patients will develop either a locoregional recurrence or distant metastasis. It is, therefore, necessary to explore novel and effective treatment strategies to improve the clinical efficacy of treatment. Immunotherapy utilizing immune checkpoint inhibitors (ICIs) has significantly changed the treatment paradigm for a wide variety of advanced cancers, including EC. More recently, increasing clinical evidence has demonstrated that neoadjuvant immunotherapy can potentially improve the survival of patients with resectable cancers. Furthermore, accumulating findings support the idea that chemotherapy and/or radiotherapy can activate the immune system through a variety of mechanisms, so a combination of chemotherapy and/or radiotherapy with immunotherapy can have a synergistic antitumor effect. Therefore, it is reasonable to evaluate the role of neoadjuvant immunotherapy for patients with surgically resectable EC. In this review, we discuss the rationale for neoadjuvant immunotherapy in patients with EC, summarize the current results of utilizing this strategy, review the planned and ongoing studies, and highlight the challenges and future research needs.

Improved Tumor Responses with Sequential Targeted α-Particles Followed by Interleukin 2 Immunocytokine Therapies in Treatment of CEA-Positive Breast and Colon Tumors in CEA Transgenic Mice

Targeted α-therapy (TAT) delivers high-linear-transfer-energy α-particles to tumors with the potential to generate tumor immune responses that may be augmented by antigen-targeted immunotherapy. Methods: This concept was evaluated in immunocompetent carcinoembryonic antigen (CEA) transgenic mice bearing CEA-positive mammary or colon tumors. Tumors were targeted with humanized anti-CEA antibody M5A labeled with ²²⁵Ac for its 10-d half-life and emission of 4 α-particles, as well as being targeted with the immunocytokine M5A-interleukin 2. Results: A dose response (3.7, 7.4, and 11.1 kBq) to TAT only, for orthotopic CEA-positive mammary tumors, was observed, with a tumor growth delay of 30 d and an increase in median survival from 20 to 36 d at the highest dose. Immunocytokine (4 times daily) monotherapy gave a tumor growth delay of 20 d that was not improved by addition of 7.4 kBq of TAT 5 d after the start of immunocytokine. However, TAT (7.4 kBq) followed by immunocytokine 10 d later led to a tumor growth delay of 38 d, with an increase in median survival to 45 d. Similar results were seen for TAT followed by immunocytokine at 5 versus 10 d. When a similar study was performed with subcutaneously implanted CEA-positive MC38 colon tumors, TAT (7.4 kBq) monotherapy gave an increase in median survival from 29 to 42 d. The addition of immunocytokine 10 d after 7.4 kBq of TAT increased median survival to 57 d. Immunophenotyping showed increased tumor-infiltrating interferon-γ-positive, CD8-positive T cells and an increased ratio of these cells to Foxp3-positive, CD4-positive regulatory T cells with sequential therapy. Immunohistochemistry confirmed there was an increase in tumor-infiltrating CD8-positive T cells in the sequential therapy group, strongly suggesting that immunocytokine augmented TAT can lead to an immune response that improves tumor therapy. Conclusion: Low-dose (7.4 kBq) TAT followed by a 4-dose immunocytokine regimen 5 or 10 d later gave superior tumor reductions and survival curves compared with either monotherapy in breast and colon cancer tumor models. Reversing the order of therapy to immunocytokine followed by TAT 5 d later was equivalent to either monotherapy in the breast cancer model.

Modulation of Reactive Oxygen Species in Cancers: Recent Advances

Oxidation-reduction reactions played a significant role in the chemical evolution of life forms on oxygenated earth. Cellular respiration is dependent on such redox reactions, and any imbalance leads to the accumulation of reactive oxygen species (ROS), resulting in both chronic and acute illnesses. According to the International Agency for Research on Cancer (IARC), by 2040, the global burden of new cancer cases is expected to be around 27.5 million, with 16.3 million cancer deaths due to an increase in risk factors such as unhealthy lifestyle, environmental factors, aberrant gene mutations, and resistance to therapies. ROS play an important role in cellular signalling, but they can cause severe damage to tissues when present at higher levels. Elevated and chronic levels of ROS are pertinent in carcinogenesis, while several therapeutic strategies rely on altering cellular ROS to eliminate tumour cells as they are more susceptible to ROS-induced damage than normal cells. Given this selective targeting potential, therapies that can effectively modulate ROS levels have been the focus of intense research in recent years. The current review describes biologically relevant ROS, its origins in solid and haematological cancers, and the current status of evolving antioxidant and pro-oxidant therapies in cancers.

Effect of neoadjuvant therapy on tumor tissue PD-L1 and VISTA expression levels in non-small-cell lung cancer

Background: PD-L1 and VISTA are important checkpoint control stations and play an immunomodulatory role in patients with non-small-cell lung cancer. Method: The expression levels of PD-L1 and VISTA between pre- and post-treatment tumor tissue were compared. Results: While PD-L1 expression was >1% in 35% of patients before neoadjuvant therapy, PD-L1 expression was >1% in 65% of patients after treatment (p = 0.004). VISTA expression was >1% in 41% of patients before treatment, and this rate was 65% after treatment (p = 0.025). Conclusion: Chemotherapy and chemoradiotherapy can be used as immunizers by increasing PD-L1 and VISTA expression levels.

Cellular bases of hypofractionated radiotherapy protocols for lung cancer

The extreme demand on health systems due to the COVID-19 pandemic has led to reconsider hypofractionation. Although the best clinical efficacy of these schemes is being demonstrated, the biological bases have not been established. Thus, after validating basic clinical parameters, through complementary in vitro models, we characterized the cellular and molecular mechanisms of hypofractionation protocols. Cell cultures of human lung cancer cell line A549 were irradiated with 0, 2, 4, 8, 12, 16 and 20 Gy. The clastogenic, cytotoxic, proliferative and clonogenic capacities and bystander effect were evaluated. In addition, we assessed survival and toxicity in a retrospective study of 49 patients with lung cancer. Our findings showed that the greater efficacy of ablative regimens should not only be attributed to events of direct cell death induced by genotoxic damage, but also to a lower cell repopulation and the indirect action of clastogenic factors secreted. These treatments were optimal in terms of 1- and 2-year overall survival (74 and 65%, respectively), and progression-free survival at 1 and 2 years (71 and 61%, respectively). The greater efficacy of high doses per fraction could be attributed to a multifactorial mechanism that goes beyond the 4Rs of conventional radiotherapy.

Radiotherapy combined with immunotherapy: the dawn of cancer treatment

Radiotherapy (RT) is delivered for purposes of local control, but can also exert systemic effect on remote and non-irradiated tumor deposits, which is called abscopal effect. The view of RT as a simple local treatment has dramatically changed in recent years, and it is now widely accepted that RT can provoke a systemic immune response which gives a strong rationale for the combination of RT and immunotherapy (iRT). Nevertheless, several points remain to be addressed such as the interaction of RT and immune system, the identification of the best schedules for combination with immunotherapy (IO), the expansion of abscopal effect and the mechanism to amplify iRT. To answer these crucial questions, we roundly summarize underlying rationale showing the whole immune landscape in RT and clinical trials to attempt to identify the best schedules of iRT. In consideration of the rarity of abscopal effect, we propose that the occurrence of abscopal effect induced by radiation can be promoted to 100% in view of molecular and genetic level. Furthermore, the “radscopal effect” which refers to using low-dose radiation to reprogram the tumor microenvironment may amplify the occurrence of abscopal effect and overcome the resistance of iRT. Taken together, RT could be regarded as a trigger of systemic antitumor immune response, and with the help of IO can be used as a radical and systemic treatment and be added into current standard regimen of patients with metastatic cancer.

The intercellular communications mediating radiation-induced bystander effects and their relevance to environmental, occupational, and therapeutic exposures

PURPOSE

The assumption that traversal of the cell nucleus by ionizing radiation is a prerequisite to induce genetic damage, or other important biological responses, has been challenged by studies showing that oxidative alterations extend beyond the irradiated cells and occur also in neighboring bystander cells. Cells and tissues outside the radiation field experience significant biochemical and phenotypic changes that are often similar to those observed in the irradiated cells and tissues. With relevance to the assessment of long-term health risks of occupational, environmental and clinical exposures, measurable genetic, epigenetic, and metabolic changes have been also detected in the progeny of bystander cells. How the oxidative damage spreads from the irradiated cells to their neighboring bystander cells has been under intense investigation. Following a brief summary of the trends in radiobiology leading to this paradigm shift in the field, we review key findings of bystander effects induced by low and high doses of various types of radiation that differ in their biophysical characteristics. While notable mechanistic insights continue to emerge, here the focus is on the many means of intercellular communication that mediate these effects, namely junctional channels, secreted molecules and extracellular vesicles, and immune pathways.

CONCLUSIONS

The insights gained by studying radiation bystander effects are leading to a basic understanding of the intercellular communications that occur under mild and severe oxidative stress in both normal and cancerous tissues. Understanding the mechanisms underlying these communications will likely contribute to reducing the uncertainty of predicting adverse health effects following exposure to low dose/low fluence ionizing radiation, guide novel interventions that mitigate adverse out-of-field effects, and contribute to better outcomes of radiotherapeutic treatments of cancer. In this review, we highlight novel routes of intercellular communication for investigation, and raise the rationale for reconsidering classification of bystander responses, abscopal effects, and expression of genomic instability as non-targeted effects of radiation.

A rare and complete response to combination therapy with radiation and nivolumab in a patient with metastatic urothelial cancer

According to the current understanding, radiotherapy can enhance the effectiveness of cancer immunotherapy due to radiation-induced release of tumour-associated antigens. Here, we present a case with a metastatic urothelial carcinoma who received nivolumab and palliative radiotherapy to a residual tumour in the vagina and to a large metastatic visceral lymph node. The treatment resulted in a rapid and virtually complete response for the time being in all metastases and in the large parailiac tumour mass. Follow up continues. The presented case demonstrates that the combinatory treatment with radiotherapy and immunotherapy can result in an exceptional response for the benefit of the patient with urothelial cancer. To our knowledge, this is one of the largest metastatic masses to disappear with a combination of immuno-oncologic (nivolumab) and radiation therapies.

The role of autophagy in initiation, progression, TME modification, diagnosis, and treatment of esophageal cancers

Autophagy is a highly conserved metabolic process with a cytoprotective function. Autophagy is involved in cancer, infection, immunity, and inflammation and may be a potential therapeutic target. Increasing evidence has revealed that autophagy has primary implications for esophageal cancer, including its initiation, progression, tumor microenvironment (TME) modification, diagnosis, and treatment. Notably, autophagy displayed excellent application potential in radiotherapy combined with immunotherapy. Radiotherapy combined with immunotherapy is a new potential therapeutic strategy for cancers, including esophageal cancer. Autophagy modulators can work as adjuvant enhancers in radiotherapy or immunotherapy of cancers. This review highlights the most recent data related to the role of autophagy regulation in esophageal cancer.

A Review of the Effects of Cervical Cancer Standard Treatment on Immune Parameters in Peripheral Blood, Tumor Draining Lymph Nodes, and Local Tumor Microenvironment

Cervical cancer remains a public health concern despite all the efforts to implement vaccination and screening programs. Conventional treatment for locally advanced cervical cancer consists of surgery, radiotherapy (with concurrent brachytherapy), combined with chemotherapy, or hyperthermia. The response rate to combination approaches involving immunomodulatory agents and conventional treatment modalities have been explored but remain dismal in patients with locally advanced disease. Studies exploring the immunological effects exerted by combination treatment modalities at the different levels of the immune system (peripheral blood (PB), tumor-draining lymph nodes (TDLN), and the local tumor microenvironment (TME)) are scarce. In this systemic review, we aim to define immunomodulatory and immunosuppressive effects induced by conventional treatment in cervical cancer patients to identify the optimal time point for immunotherapy administration. Radiotherapy (RT) and chemoradiation (CRT) induce an immunosuppressive state characterized by a long-lasting reduction in peripheral CD3, CD4, CD8 T cells and NK cells. At the TDLN level, CRT induced a reduction in Nrp1+Treg stability and number, naïve CD4 and CD8 T cell numbers, and an accompanying increase in IFNγ-producing CD4 helper T cells, CD8 T cells, and NK cells. Potentiation of the T-cell anti-tumor response was particularly observed in patients receiving low irradiation dosage. At the level of the TME, CRT induced a rebound effect characterized by a reduction of the T-cell anti-tumor response followed by stable radioresistant OX40 and FoxP3 Treg cell numbers. However, the effects induced by CRT were very heterogeneous across studies. Neoadjuvant chemotherapy (NACT) containing both paclitaxel and cisplatin induced a reduction in stromal FoxP3 Treg numbers and an increase in stromal and intratumoral CD8 T cells. Both CRT and NACT induced an increase in PD-L1 expression. Although there was no association between pre-treatment PD-L1 expression and treatment outcome, the data hint at an association with pro-inflammatory immune signatures, overall and disease-specific survival (OS, DSS). When considering NACT, we propose that posterior immunotherapy might further reduce immunosuppression and chemoresistance. This review points at differential effects induced by conventional treatment modalities at different immune compartments, thus, the compartmentalization of the immune responses as well as individual patient's treatment plans should be carefully considered when designing immunotherapy treatment regimens.

From Photon Beam to Accelerated Particle Beam: Antimetastasis Effect of Combining Radiotherapy With Immunotherapy

Cancer is one of the major diseases that seriously threaten the human health. Radiotherapy is a common treatment for cancer. It is noninvasive and retains the functions of the organ where the tumor is located. Radiotherapy includes photon beam radiotherapy, which uses X-rays or gamma rays, and particle beam radiotherapy, using beams of protons and heavy ions. Compared with photon beam radiotherapy, particle beam radiotherapy has excellent dose distribution, which enables it to kill the primary tumor cells more effectively and simultaneously minimize the radiation-induced damage to normal tissues and organs surrounding the tumor. Despite the excellent therapeutic effect of particle beam radiotherapy on the irradiated tumors, it is not an effective treatment for metastatic cancers. Therefore, developing novel and effective treatment strategies for cancer is urgently needed to save patients with distant cancer metastasis. Immunotherapy enhances the body's own immune system to fight cancer by activating the immune cells, and consequently, to achieve the systemic anticancer effects, and it is considered to be an adjuvant therapy that can enhance the efficacy of particle beam radiotherapy. This review highlights the research progress of the antimetastasis effect and the mechanism of the photon beam or particle beam radiotherapy combined with immunotherapy and predicts the development prospects of this research area.

Efficacy of radiotherapy combined with immune checkpoint inhibitors in patients with melanoma: a systemic review and meta-analysis

The purpose of this study is to review the efficacy of radiotherapy combined with immune checkpoint inhibitors (ICIs) in the treatment of melanoma and systematically evaluate the efficacy and safety of this combined treatment compared with ICIs alone. We searched a number of online databases up to 1 July 2021. Comprehensive Meta-Analysis 2.0 and RevMan 5.0 were used for summary analysis. The overall survival (OS), progression-free survival (PFS), overall response rate (ORR) and treatment adverse effects (AEs) were calculated. In total, 624 patients were included from 12 studies, including nine published studies and the results of three clinical trials. Radiotherapy combined with ICIs had a higher ORR compared with ICIs alone (35.00 vs. 20.39%). In terms of survival effect, radiotherapy combined with ICIs had no obvious advantage in OS. There was no statistically significant difference between 6-month and 12-month OS (P = 0.13; P = 0.69). There was no significant difference in PFS at 6 months (P = 0.08), but there was a significant difference in PFS at 12 months (P = 0.005). For patients with melanoma, radiotherapy combined with ICIs can improve the effective rate of treatment. Although there is no obvious OS advantage, it can improve PFS without serious adverse effects. Most of the studies included in this article are retrospective analyses, and there are few randomized controlled studies at present. Therefore, more prospective studies are still needed to explore the efficacy of radiotherapy combined with immunotherapy in melanoma.

Irradiation immunity interactions

The immune system can influence cancer development by both impeding and/or facilitating tumour growth and spread. A better understanding of this complex relationship is fundamental to optimise current and future cancer therapeutic strategies. Although typically regarded as a localised and immunosuppressive anti‐cancer treatment modality, radiation therapy has been associated with generating profound systemic effects beyond the intended target volume. These systemic effects are immune‐driven suggesting radiation therapy can enhance anti‐tumour immunosurveillance in some instances. In this review, we summarise how radiation therapy can positively and negatively affect local and systemic anti‐tumour immune responses, how co‐administration of immunotherapy with radiation therapy may help promote anti‐tumour immunity, and how the use of immune biomarkers may help steer radiation therapy‐immunotherapy personalisation to optimise clinical outcomes.

Radiotherapy: Brightness and darkness in the era of immunotherapy

The introduction of immunotherapy into cancer treatment has radically changed clinical management of tumors. However, only a minority of patients (approximately 10 to 30%) exhibit long-term response to monotherapy with immunotherapy. Moreover, there are still many cancer types, including pancreatic cancer and glioma, which are resistant to immunotherapy. Due to the immunomodulatory effects of radiotherapy, the combination of radiotherapy and immunotherapy has achieved better therapeutic effects in a number of clinical trials. However, radiotherapy is a double-edged sword in the sense that it also attenuates the immune system under certain doses and fractionation schedules, not all clinical trials show improved survival in the combination of radiotherapy and immunotherapy. Therefore, elucidation of the interactions between radiotherapy and the immune system is warranted to optimize the synergistic effects of radiotherapy and immunotherapy. In this review, we highlight the dark side as well as bright side of radiotherapy on tumor immune microenvironment and immune system. We also elucidate current status of radioimmunotherapy, both in preclinical and clinical studies, and highlight that combination of radiotherapy and immunotherapy attenuates combinatorial effects in some circumstances. Moreover, we provide insights for better combination of radiotherapy and immunotherapy.

Tumor-Infiltrating Lymphocytes (TILs) as a Biomarker of Abscopal Effect of Cryoablation in Breast Cancer: A Pilot Study

Background

Morphological evaluation of tumor-infiltrating lymphocytes (TILs) in breast cancer is gaining momentum as an immunological biomarker. This experiment evaluates the role of TILs in distant tumors as a measure of abscopal effect from cryoablation of breast cancer.

Methods

BALB/c mice underwent bilateral orthotopic transplant with 4T1-12B (triple-negative) cells. At 2 weeks, left tumors were treated by either resection (standard of care group) or cryoablation (intervention group) followed by resection of the distant right tumors 1 week posttreatment. TIL scores were calculated from hematoxylin and eosin-stained sections and phenotyped for cytotoxic T-lymphocyte (CTL) markers by immunofluorescence. Primarily resected tumors served as baseline (Tbaseline), whereas resected distant right-sided served as the readout for abscopal effect (AbsRes or AbsCryo). Mice were monitored for tumor recurrence and metastasis.

Results

The AbsCryo had a significant mean (SD) increase in stromal (2.8 [1.1]%; p = 0.015) and invasive margin TILs (50 [12]%; p = 0.02) compared with TBaseline (1.0 [0]% and 31 [4.9]%, respectively). CTL phenotyping revealed a significant increase in mean (SD) CD8+ T cells (15.7 [12.1]; p = 0.02) and granzyme B (4.8 [3.6]; p = 0.048) for the AbsCryo compared with TBaseline (5.2 [4.7] and 2.4 [0.9], respectively). Posttreatment, the cryoablation group had no recurrence or metastasis, whereas the resected group showed local recurrence and lung metastasis in 40% of the mice. Postprocedure increase in TIL score of distant tumors was associated with decrease in tumor relapse (p = 0.02).

Conclusions

Cryoablation induced a robust tumor-specific TIL response compared with resection, suggesting an abscopal effect leading to the prevention of cancer recurrence and metastasis.

Divide and conquer: spatially fractionated radiation therapy

Spatially fractionated radiation therapy (SFRT) challenges some of the classical dogmas in conventional radiotherapy. The highly modulated spatial dose distributions in SFRT have been shown to lead, both in early clinical trials and in small animal experiments, to a significant increase in normal tissue dose tolerances. Tumour control effectiveness is maintained or even enhanced in some configurations as compared with conventional radiotherapy. SFRT seems to activate distinct radiobiological mechanisms, which have been postulated to involve bystander effects, microvascular alterations and/or immunomodulation. Currently, it is unclear which is the dosimetric parameter which correlates the most with both tumour control and normal tissue sparing in SFRT. Additional biological experiments aiming at parametrizing the relationship between the irradiation parameters (beam width, spacing, peak-to-valley dose ratio, peak and valley doses) and the radiobiology are needed. A sound knowledge of the interrelation between the physical parameters in SFRT and the biological response would expand its clinical use, with a higher level of homogenisation in the realisation of clinical trials. This manuscript reviews the state of the art of this promising therapeutic modality, the current radiobiological knowledge and elaborates on future perspectives.

Combination therapy with immune checkpoint inhibitors (ICIs); a new frontier

Recently, immune checkpoint inhibitors (ICIs) therapy has become a promising therapeutic strategy with encouraging therapeutic outcomes due to their durable anti-tumor effects. Though, tumor inherent or acquired resistance to ICIs accompanied with treatment-related toxicities hamper their clinical utility. Overall, about 60-70% of patients (e.g., melanoma and lung cancer) who received ICIs show no objective response to intervention. The resistance to ICIs mainly caused by alterations in the tumor microenvironment (TME), which in turn, supports angiogenesis and also blocks immune cell antitumor activities, facilitating tumor cells' evasion from host immunosurveillance. Thereby, it has been supposed and also validated that combination therapy with ICIs and other therapeutic means, ranging from chemoradiotherapy to targeted therapies as well as cancer vaccines, can capably compromise tumor resistance to immune checkpoint blocked therapy. Herein, we have focused on the therapeutic benefits of ICIs as a groundbreaking approach in the context of tumor immunotherapy and also deliver an overview concerning the therapeutic influences of the addition of ICIs to other modalities to circumvent tumor resistance to ICIs.

SIRT in 2025

Selective internal radiation therapy represents an endovascular treatment option for patients with primary liver malignancies, in different clinical stages. Potential applications of this treatment are in early-stage hepatocellular carcinoma, as a curative option, or in combination with systemic treatments in intermediate and advanced-stages. This review, based on existing literature and ongoing trials, will focus on the future of this treatment in patients with hepatocellular carcinoma, in combination with systemic treatments, or with the use of new devices and technological developments; it will also describe new potential future indications and structural and organizational perspectives.

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.