Radiotherapy combined with nano-biomaterials for cancer radio-immunotherapy.

Radiotherapy (RT) plays an important role in tumor therapy due to its noninvasiveness and wide adaptation. In recent years, radiation therapy has been discovered to induce an anti-tumor immune response, which arouses widespread concern among scientists and clinicians. In this review, we highlight recent advances in the applications of nano-biomaterials for radiotherapy-activated immunotherapy. We first discuss the combination of different radiosensitizing nano-biomaterials and immune checkpoint inhibitors to enhance tumor immune response and improve radiotherapy efficacy. Subsequently, various nano-biomaterials-enabled tumor oxygenation strategies are introduced to alleviate the hypoxic tumor environment and amplify the immunomodulatory effect. With the aid of nano-vaccines and adjuvants, radiotherapy refreshes the host's immune system. Additionally, ionizing radiation responsive nano-biomaterials raise innate immunity-mediated anti-tumor immunity. At last, we summarize the rapid development of immune modulatable nano-biomaterials and discuss the key challenge in the development of nano-biomaterials for tumor radio-immunotherapy. Understanding the nano-biomaterials-assisted radio-immunotherapy will maximize the benefits of clinical radiotherapy and immunotherapy and facilitate the development of new combinational therapy modality.

Treatment of Cancer with Radio-Immunotherapy: What We Currently Know and What the Future May Hold.

Radiotherapy and immunotherapy are most effective as cancer therapies in the setting of low-volume disease. Although initial studies of radio-immunotherapy in patients with metastatic cancer have not confirmed the efficacy of this approach, the role of radio-immunotherapy in patients with limited metastatic burden is unclear. We propose that further investigation of radio-immunotherapy in metastatic patients should focus upon patients with oligometastatic disease.

Immunomodulation by ionizing radiation-impact for design of radio-immunotherapies and for treatment of inflammatory diseases.

Ionizing radiation is often regarded as an element of danger. But, danger responses on the cellular and molecular level are often beneficial with regard to the induction of anti-tumor immunity and for amelioration of inflammation. We outline how in dependence of radiation dose and fraction, radiation itself-and especially in combination with immune modulators-impacts on the innate and adaptive immune system. Focus is set on radiation-induced changes of the tumor cell phenotype and the cellular microenvironment including immunogenic cancer cell death. Mechanisms how anti-tumor immune responses are triggered by radiotherapy in combination with hyperthermia, inhibition of apoptosis, the adjuvant AnnexinA5, or vaccination with high hydrostatic pressure-killed autologous tumor cells are discussed. Building on this, feasible multimodal radio-immunotherapy concepts are reviewed including overcoming immune suppression by immune checkpoint inhibitors and by targeting TGF-ß. Since radiation-induced tissue damage, inflammation, and anti-tumor immune responses are interconnected, the impact of lower doses of radiation on amelioration of inflammation is outlined. Closely meshed immune monitoring concepts based on the liquid biopsy blood are suggested for prognosis and prediction of cancer and non-cancer inflammatory diseases. Finally, challenges and visions for the design of cancer radio-immunotherapies and for treatment of benign inflammatory diseases are given.

I131 reinforces antitumor activity of metuximab by reversing epithelial-mesenchymal transition via VEGFR-2 signaling in hepatocellular carcinoma.

CD147 is highly expressed in hepatocellular carcinoma (HCC) and associated with the invasion and metastasis of HCC. The efficacy of I131 -metuximab (I131 -mab), a newly developed agent that targets CD147, as a radio-immunotherapy for local HCC, has been validated in clinical practice. However, the synergistic anticancer activity and molecular mechanism of different conjugated components within I131 -mab remain unclear. In this study, the cytological experiments proved that I131 -mab inhibited the proliferation and invasion of HCC cells. Mechanically, this inhibition effect was mainly mediated by the antibody component part of I131 -mab, which could reverse the epithelial-mesenchymal transition of HCC cells partially by suppressing the phosphorylation of VEGFR-2. The inhibitory effect of I131 on HCC cell proliferation and invasion is limited, whereas, when combined with metuximab, I131 significantly enhanced the sensitivity of HCC cells to CD147-mab and consequently reinforced the anticancer effects of CD147-mab, suggesting that the two components of I131 -mab exerted synergistic anti-HCC capability. Furthermore, the experiments using SMMC-7721 human HCC xenografts in athymic nude mice showed that I131 -mab and CD147-mab significantly inhibited the growth of xenograft tumors and that I131 -mab was more effective than CD147-mab. In conclusion, our results elucidated the mechanism underlying the anti-HCC effects of I131 -mab and provided a theoretical foundation for the clinical application of I131 -mab.

Management of newly diagnosed high-risk and intermediate-risk follicular lymphoma with 90 Y ibritumomab tiuxetan in a phase II study.

Five-year overall survival for high-risk Follicular Lymphoma International Prognostic Index follicular lymphoma is only approximately 50% compared with 90% for low risk. To evaluate an approach to improve upon this poor outcome, we completed an exploratory phase II trial of intensified treatment for patients with intermediate and high-risk follicular lymphoma. Front-line treatment with chemo-immunotherapy consisting of rituximab, cyclophosphamide, vincristine, doxorubicin, and prednisone was followed by radio- immunotherapy with 90-Yttrium ibritumomab tiuxetan consolidation, and 2 years of rituximab maintenance. The 5-year overall survival for intermediate and high-risk patients was 88% and 83%, respectively. Of 33 enrolled patients, 3 were off study before receiving radio-immunotherapy. Three months post radio-immunotherapy, 28/33 (85%) patients had achieved complete response including 6 patients who had only a partial response to chemo-immunotherapy and converted to complete response after radio-immunotherapy. The 5-year progression-free survival for intermediate and high risk was 79% and 58%, respectively. Nine of 19 patients with molecular markers patients remain in molecular and clinical complete remission with a median follow-up of 48 months (range 3-84 months). Post radio-immunotherapy, hematologic toxicities were mostly grade 1 and 2. However, asymptomatic grade 3 or 4 thrombocytopenia and neutropenia occurred in 11%-36% and 10%-24% of patients, respectively. Myelodysplastic syndrome occurred in 1 patient 4 years post treatment. Whereas many patients had prolonged B-cell reduction and low immunoglobulin levels post treatment, previous immunities to rubella were maintained. More aggressive upfront approaches such as this may benefit higher risk follicular lymphoma, but confirmatory trials are required. http://www.clinicaltrials.gov: NCT01446562.

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

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

Can local radiotherapy and IL-12 synergise to overcome the immunosuppressive tumor microenvironment and allow "in situ tumor vaccination"?

The abscopal effect, which is the spontaneous regression of tumors or metastases outside the radiation field, occurs rarely in cancer patients. Interestingly, radiotherapy (RT) triggers an immunogenic cell death (ICD) that is able to generate tumor-specific cytotoxic CD8+ T cells that are efficient in killing cancer cells. The key question is: why is this "abscopal effect" so uncommon in cancer patients treated with RT? Most probably, the main reason may be related to the highly immunosuppressive tumor microenvironment of well-established tumors that constantly antagonizes the anti-tumor immune responses triggered by RT. In this case, additional or combinatorial immunotherapy is needed to attenuate these immunosuppressive networks and, therefore, substantially increases the efficacy of RT. Here, we describe a potentially promising synergistic radio-immunotherapy "in situ tumor vaccination" protocol by antagonizing the tumor-immunosuppressive microenvironment with a combinatorial approach using local RT and IL-12-based TH1 response augmentation.

Targeted Radionuclide Therapy of Human Tumors.

Targeted radionuclide therapy is one of the most intensively developing directions of nuclear medicine. Unlike conventional external beam therapy, the targeted radionuclide therapy causes less collateral damage to normal tissues and allows targeted drug delivery to a clinically diagnosed neoplastic malformations, as well as metastasized cells and cellular clusters, thus providing systemic therapy of cancer. The methods of targeted radionuclide therapy are based on the use of molecular carriers of radionuclides with high affinity to antigens on the surface of tumor cells. The potential of targeted radionuclide therapy has markedly grown nowadays due to the expanded knowledge base in cancer biology, bioengineering, and radiochemistry. In this review, progress in the radionuclide therapy of hematological malignancies and approaches for treatment of solid tumors is addressed.

Biomimetic liposome amplifying mitochondrial damage to potential cancer radio-immunotherapy.

Radiotherapy, despite its precision and non-invasiveness, often fails due to the resistance of cancer stem cells (CSCs), which are characterized by high self-renewal capabilities and superior DNA repair mechanisms. These cells can evade RT and lead to tumor recurrence and metastasis. To address this challenge, a novel delivery system named PB has been introduced. This system combines liposomes with platelet membranes to encapsulate Bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl) ethyl sulfide (BPTES), thus enhancing its delivery and release specifically at tumor sites. In addition, this system not only targets CSCs effectively but also increases the local concentration of BPTES upon X-ray irradiation, which reduces glutathione levels in tumor cells, thereby increasing oxidative stress and damaging mitochondria. PB-elicited mitochondrial damage as the STING signal initiator, which mediated significant upregulation in the expression of a cGAS-STING pathway-related protein thereby amplifying the STING signal. Systemic intravenous administration of PB remarkably promoted DC maturation and CD8+ T cell infiltration, thus eliciting strong antitumor effects. Overall, this PB system presents a potent method to overcome CSC-related resistance and offers a promising approach for future cancer treatment protocols.

An Immunocompetent Hafnium Oxide-Based STING Nanoagonist for Cancer Radio-immunotherapy.

cGAS-STING signaling plays a critical role in radiotherapy (RT)-mediated immunomodulation. However, RT alone is insufficient to sustain STING activation in tumors under a safe X-ray dose. Here, we propose a radiosensitization cooperated with cGAS stimulation strategy by engineering a core-shell structured nanosized radiosensitizer-based cGAS-STING agonist, which is constituted with the hafnium oxide (HfO2) core and the manganese oxide (MnO2) shell. HfO2-mediated radiosensitization enhances immunogenic cell death to afford tumor associated antigens and adequate cytosolic dsDNA, while the GSH-degradable MnO2 sustainably releases Mn2+ in tumors to improve the recognition sensitization of cGAS. The synchronization of sustained Mn2+ supply with cumulative cytosolic dsDNA damage synergistically augments the cGAS-STING activation in irradiated tumors, thereby enhancing RT-triggered local and system effects when combined with an immune checkpoint inhibitor. Therefore, the synchronous radiosensitization with sustained STING activation is demonstrated as a potent immunostimulation strategy to optimize cancer radio-immuotherapy.

Engineered bacteria breach tumor physical barriers to enhance radio-immunotherapy.

Radiotherapy widely applied for local tumor therapy in clinic has been recently reinvigorated by the discovery that radiotherapy could activate systematic antitumor immune response. Nonetheless, the endogenous radio-immune effect is still incapable of radical tumor elimination due to the prevention of immune cell infiltration by the physical barrier in tumor microenvironment (TME). Herein, an engineered Salmonella secreting nattokinase (VNPNKase) is developed to synergistically modulate the physical and immune characteristics of TME to enhance radio-immunotherapy of colon tumors. The facultative anaerobic VNPNKase enriches at the tumor site after systemic administration, continuously secreting abundant NKase to degrade fibronectin, dredge the extracellular matrix (ECM), and inactivate cancer-associated fibroblasts (CAFs). The VNPNKase- dredged TME facilitates the infiltration of CD103+ dendritic cells (DCs) and thus the presentation of tumor-associated antigens (TAAs) after radiotherapy, recruiting sufficient CD8+ T lymphocytes to specifically eradicate localized tumors. Moreover, the pre-treatment of VNPNKase before radiotherapy amplifies the abscopal effect and achieves a long-term immune memory effect, preventing the metastasis and recurrence of tumors. Our research suggests that this strategy using engineered bacteria to breach tumor physical barrier for promoting immune cell infiltration possesses great promise as a translational strategy to enhance the effectiveness of radio-immunotherapy in treating solid tumors.

A combined radio-immunotherapy regimen eradicates late-stage tumors in mice.

Background: The majority of experimental approaches for cancer immunotherapy are tested against relatively small tumors in tumor-bearing mice, because in most cases advanced cancers are resistant to the treatments. In this study, we asked if even late-stage mouse tumors can be eradicated by a rationally designed combined radio-immunotherapy (CRI) regimen. Methods: CRI consisted of local radiotherapy, intratumoral IL-12, slow-release systemic IL-2 and anti- CTLA-4 antibody. Therapeutic effects of CRI against several weakly immunogenic and immunogenic mouse tumors including B78 melanoma, MC38 and CT26 colon carcinomas and 9464D neuroblastoma were evaluated. Immune cell depletion and flow cytometric analysis were performed to determine the mechanisms of the antitumor effects. Results: Tumors with volumes of 2,000 mm3 or larger were eradicated by CRI. Flow analyses of the tumors revealed reduction of T regulatory (Treg) cells and increase of CD8/Treg ratios following CRI. Rapid shrinkage of the treated tumors did not require T cells, whereas T cells were involved in the systemic effect against the distant tumors. Cured mice developed immunological memory. Conclusions: These findings underscore that rationally designed combination immunotherapy regimens can be effective even against large, late-stage tumors.

Bimetallic nanoparticles as cascade sensitizing amplifiers for low-dose and robust cancer radio-immunotherapy.

Radiotherapy (RT) is one of the most feasible and routinely used therapeutic modalities for treating malignant tumors. In particular, immune responses triggered by RT, known as radio-immunotherapy, can partially inhibit the growth of distantly spreading tumors and recurrent tumors. However, the safety and efficacy of radio-immunotherapy is impeded by the radio-resistance and poor immunogenicity of tumor. Herein, we report oxaliplatin (IV)-iron bimetallic nanoparticles (OXA/Fe NPs) as cascade sensitizing amplifiers for low-dose and robust radio-immunotherapy. The OXA/Fe NPs exhibit tumor-specific accumulation and activation of OXA (II) and Fe2+ in response to the reductive and acidic microenvironment within tumor cells. The cascade reactions of the released metallic drugs can sensitize RT by inducing DNA damage, increasing ROS and O2 levels, and amplifying the immunogenic cell death (ICD) effect after RT to facilitate potent immune activation. As a result, OXA/Fe NPs-based low-dose RT triggered a robust immune response and inhibited the distant and metastatic tumors effectively by a strong abscopal effect. Moreover, a long-term immunological memory effect to protect mice from tumor rechallenging is observed. Overall, the bimetallic NPs-based cascade sensitizing amplifier system offers an efficient radio-immunotherapy regimen that addresses the key challenges.

A Hybrid Nanoadjuvant Simultaneously Depresses PD-L1/TGF-ß1 and Activates cGAS-STING Pathway to Overcome Radio-Immunotherapy Resistance.

Currently, certain cancer patients exhibit resistance to radiotherapy due to reduced DNA damage under hypoxic conditions and acquired immune tolerance triggered by transforming growth factor-ß1 (TGF-ß1) and membrane-localized programmed death ligand-1 (PD-L1). Meanwhile, cytoplasm-distributed PD-L1 induces radiotherapy resistance through accelerating DNA damage repair (DDR). However, the disability of clinically used PD-L1 antibodies in inhibiting cytoplasm-distributed PD-L1 limits their effectiveness. Therefore, a nanoadjuvant is developed to sensitize cancer to radiotherapy via multi-level immunity activation through depressing PD-L1 and TGF-ß1 by triphenylphosphine-derived metformin, and activating the cGAS-STING pathway by generating Mn2+ from MnO2 and producing more dsDNA via reversing tumor hypoxia and impairing DDR. Thus, Tpp-Met@MnO2@Alb effectively enhances the efficiency of radiotherapy to inhibit the progression of irradiated local and abscopal tumors and tumor lung metastases, offering a long-term memory of antitumor immunity without discernible side effects. Overall, Tpp-Met@MnO2@Alb has the potential to be clinically applied for overcoming radio-immunotherapy resistance.

A Polymeric Hydrogel to Eliminate Programmed Death-Ligand 1 for Enhanced Tumor Radio-Immunotherapy.

Programmed death-ligand 1 (PD-L1) is a specialized shield on tumor cells that evades the immune system. Even inhibited by PD-L1 antibodies, a cycling process constantly transports PD-L1 from inside to outside of cells, facilitating the renewal and replenishment of PD-L1 on the cancer cell membrane. Herein, we develop a sodium alginate hydrogel consisting of elesclomol-Cu and galactose to induce persistent cuproptosis, leading to the reduction of PD-L1 for radio-immunotherapy of colon tumors. First, a prefabricated hydrogel is synthesized by immobilizing elesclomol onto a sodium alginate saccharide chain through the coordination with bivalent copper ions (Cu2+), followed by incorporation of galactose. After implantation into the tumors, this prefabricated hydrogel can be further cross-linked in the presence of physiological calcium ions (Ca2+), resulting in the formation of a hydrogel with controlled release of elesclomol-Cu2+ (ES-Cu) and galactose. The hydrogel effectively induces the oligomerization of DLAT and cuproptosis in colorectal cancer cells. Interestingly, radiation-induced PD-L1 upregulation is abrogated in the presence of the hydrogel, releasing ES-Cu and galactose. Consequently, the sensitization of tumor to radiotherapy and immunotherapy is significantly improved, further prolonging the survival of tumor-bearing mice in both local and metastatic tumors. Our study introduces an approach that combines cuproptosis with immunotherapy and radiotherapy.

Precise Engineering of a Se/Te Nanochaperone for Reinvigorating Cancer Radio-Immunotherapy.

Facilely synthesized nanoradiosensitizers with well-controlled structure and multifunctionality are greatly desired to address the challenges of cancer radiotherapy. In this work, a universal method is developed for synthesizing chalcogen-based TeSe nano-heterojunctions (NHJs) with rod-, spindle-, or dumbbell-like morphologies by engineering the surfactant and added selenite. Interestingly, dumbbell-shaped TeSe NHJs (TeSe NDs) as chaperone exhibit better radio-sensitizing activities than the other two nanostructural shapes. Meanwhile, TeSe NDs can serve as cytotoxic chemodrugs that degrade to highly toxic metabolites in acidic environment and deplete GSH within tumor to facilitate radiotherapy. More importantly, the combination of TeSe NDs with radiotherapy significantly decreases regulatory T cells and M2-phenotype tumor-associated macrophage infiltrations within tumors to reshape the immunosuppressive microenvironment and induce robust T lymphocytes-mediated antitumor immunity, resulting in great abscopal effects on combating distant tumor progression. This study provides a universal method for preparing NHJ with well-controlled structure and developing nanoradiosensitizers to overcome the clinical challenges of cancer radiotherapy.

Exploring low-dose radiotherapy to overcome radio-immunotherapy resistance.

Immune checkpoint inhibitors (ICIs) have revolutionized the current treatment landscape for cancer, yet the response rates of ICIs remain unmet. Synergistic with immunotherapy, low-dose radiotherapy (LDRT) has been demonstrated to activate anti-tumor immunity - a transition from traditional radiation therapy geared toward local radical treatment to a type of immunological adjuvant. As such, studies utilizing LDRT to enhance the efficacy of immunotherapy have been increasing preclinically and clinically. This paper reviews the recent strategies of using LDRT to overcome the resistance of ICIs, as well as providing potential opportunities in cancer treatment. Despite the potential of LDRT in immunotherapy is recognized, the mechanisms behind this form of treatment remain largely elusive. Thus, we reviewed history, mechanisms and challenges associated with this form of treatment, as well as different modes of its application, to provide relatively accurate practice standards for LDRT as a sensitizing treatment when combined with immunotherapy or radio-immunotherapy.

Radionuclide-Labeled Microspheres for Radio-Immunotherapy of Hepatocellular Carcinoma.

Brachytherapy, including radioactive seed implantation (RSI) and transarterial radiation therapy embolization (TARE), is an important treatment modality for advanced hepatocellular carcinoma (HCC), but the inability of RSI and TARE to treat tumor metastasis and recurrence limits their benefits for patients in the clinic. Herein, indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors-loaded alginate microspheres (IMs) are developed as radionuclide carriers with immunomodulatory functions to achieve effective radio-immunotherapy. The size and swelling properties of IMs can be facilely tailored by adjusting the calcium source during emulsification. Small/large IMs(SIMs/LIMs) are biocompatible and available for RSI and TARE, respectively, after 177 Lu labeling. Among them, 177 Lu-SIMs completely eliminated subcutaneous HCC in mice after intratumoral RSI. Moreover, in combination with anti-PD-L1, 177 Lu-SIMs not only eradicate primary tumors by RSI but also effectively inhibit the growth of distant tumors, wherein the potent abscopal effect can be ascribed to the immune stimulation of RSI and the modulation of the tumor immune microenvironment (TIME) by IDO1 inhibitors. In parallel, LIMs demonstrate excellent embolization efficiency, resulting in visible necrotic lesions in the central auricular artery of rabbits, which are promising for TARE in future studies. Collectively, a versatile therapeutic agent is provided to synchronously modulate the TIME during brachytherapy for efficient radio-immunotherapy of advanced HCC.

Regulation of Ion Homeostasis for Enhanced Tumor Radio-Immunotherapy.

Intra/extracellular ion content affects the growth and metastasis of tumor cells, as well as the efficacy of various antitumor therapies. Herein, a carbonic anhydrase inhibitor (CAI) is loaded onto pH-responsive calcium carbonate (CaCO3 ) nanoparticles and then modify theses nanoparticles with liposomes to obtain biocompatible CaCO3 /CAI@Lipsome (CCL) for enhance tumor radio-immunotherapy. CCL can specially decompose in tumor microenvironment, releasing calcium ion (Ca2+ ) and CAI, as well as increasing the pH value of extracellular fluid. CAI restrains the flow of hydrogen ion (H+ ) inside and outside the tumor cells, resulting in the reversal of tumor acidic microenvironment and the increase of intracellular H+ , both of which can improve the sensitivity of tumor to radiotherapy. Afterward, the increased intracellular H+ together with radiotherapy-causes reactive oxygen species promotes calcium influx, leading to cellular calcium overload. Moreover, the CCL-tailored content of H+ and Ca2+ strengthens radiotherapy-induced immunogenic cell death and dendritic cell maturation, amplifying systemic anti-tumor adaptive immunity. Meanwhile, macrophages in the CCL-treated tumors are polarized from pro-tumor M2 to anti-tumor M1 under X-ray exposure, owing to the neutralization of tumor acidic microenvironment and enhances Ca2+ content. Therefore, multi-directional regulation of the intra/extra tumor cell pH/calcium by simple nano-preparation would provide a powerful way to improve the efficacy of radio-immunotherapy.

Implications of the Organ-Specific Immune Environment for Immune Priming Effect of Radiotherapy in Metastatic Setting.

With the development of immune checkpoint inhibitors (ICIs), the tumour immune microenvironment (TIME) has been increasingly considered to improve cancer management. The TIME of metastatic lesions is strongly influenced by the underlying immune contexture of the organ in which they are located. The metastatic location itself appears to be an important prognostic factor in predicting outcomes after ICI treatment in cancer patients. Patients with liver metastases are less likely to respond to ICIs than patients with metastases in other organs, likely due to variations in the metastatic TIME. Combining additional treatment modalities is an option to overcome this resistance. Radiotherapy (RT) and ICIs have been investigated together as an option to treat various metastatic cancers. RT can induce a local and systemic immune reaction, which can promote the patient's response to ICIs. Here, we review the differential impact of the TIME according to metastatic location. We also explore how RT-induced TIME modifications could be modulated to improve outcomes of RT-ICI combinations.