Radiotherapy, immunity, and immune checkpoint inhibitors.

Radiotherapy exerts immunostimulatory and immunosuppressive effects, both locally, within the irradiated tumour microenvironment, and systemically, outside the radiation field. Inspired by preclinical data that showed synergy between radiotherapy and immune checkpoint inhibitors, multiple clinical trials were initiated with the hypothesis that combined treatment with radiotherapy and immune checkpoint inhibitors could stimulate a robust systemic immune response and improve clinical outcomes. However, despite early optimism, radioimmunotherapy trials in the curative and metastatic settings have met with little success. In this Review, we summarise the immunostimulatory effects of radiotherapy that provided the theoretical basis for trials of combination radiotherapy and immune checkpoint inhibitors. We also discuss findings from clinical trials incorporating radiotherapy and immune checkpoint inhibitors and examine the success of these trials in the context of the immunosuppressive effects of radiotherapy. We conclude by highlighting targets for relieving radiotherapy-induced immunosuppression with the goal of enhancing the combined effects of radiotherapy and immune checkpoint inhibitors.

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.

Radioligand Therapy in Lymphoma: Past, Present, and Future.

In the1980s, radiolabeled cells helped understand the pathology of hemato-oncology. In the 1990s, preclinical trials evaluated radiolabeled immunotherapy with monoclonal antibodies (MoAbs) such as anti-CD20 agents labeled with Iodine-131 (Bexxar) or Yttrium-90 (Zevalin). Due to the safe and durable responses of radiolabeled MoAbs, the Food and Drug Administration approved these agents in the 2000s. Despite radioimmunotherapy's long journey, its application has recently decreased. This review will discuss the historical timeline of radioimmunotherapy, debate on advantages and difficulties, and explore trials. We will examine future directions of radioligand therapy in hemato-oncology, considering emerging molecules that may become the next theragnostic trend.

Intranuclear Irradiation Inhibits Solid Tumor Growth by Upregulating Caspase8 and Activating Apoptosis.

Radioimmunotherapy (RIT) is a novel and promising cancer treatment method, with ongoing research focusing on RIT antibody selection, radionuclides, treatment options, and benefited patient groups. As we dive into the mechanisms of tumor biology, a deeper exploration of how RIT affects tumor tissue is needed to provide new ways to improve clinical treatment outcome and patient prognosis. We labeled the anti-PD-L1 monoclonal antibody atezolizumab with iodine-131 (131I), separated and purified the labeled mAb with Sephadex G-25 medium gel filtration resin, and tested product stability. We detected the in vivo activity of 131I-PD-L1 mAb by analyzing its in vivo biodistribution and performing SPECT imaging and then set different treatment groups to study the effect of 131I-atezolizumab on the survival of tumor-bearing mice. Western blot, real-time quantitative PCR, and immunohistochemistry were used to detect the expression level of Caspase8 and Nlrp3 in tumor. TUNEL fluorescence staining was used to detect the apoptosis in the tumor. The radiopharmaceutical molecular probe 131I-atezolizumab showed high stability and in vivo biological activity. The treatment regimen adopted had a positive effect on the survival of tumor-bearing mice. 131I internal irradiation upregulated Caspase8 in tumor and ultimately inhibited solid tumor growth by activating apoptosis pathways. We also found a significant increase in the expression of NLRP3, which plays an important role in the pyroptosis pathway, in tumor. In summary, our data demonstrated that radiopharmaceuticals combined with immunotherapy affected tumor tissue by modulating relevant biological pathways, thereby achieving better antitumor effects compared with single therapy and providing new insights for promoting better patient prognosis and combination treatment strategies.

The Rebirth of Radioimmunotherapy of Non-Hodgkin Lymphoma: The Phoenix of Nuclear Medicine?

In Greek mythology, The Phoenix is an immortal bird that dies, but then achieves new life by rising from the ashes of its predecessor. Radioimmunotherapy (RIT) of B-cell Non-Hodgkin lymphoma (NHL) is a field which once began to fly high-with FDA approval of the anti-CD20 RITs Zevalin® and Bexxar® in 2002 and 2003 respectively, as safe and effective therapies of NHL. However, despite their therapeutic efficacy, Bexxar® was withdrawn from the market by the manufacturer in 2014 due to limited commercial demand and Zevalin® has had very limited to no availability of late. I-131 rituximab is used to a limited extent in Australia, India and other countries, as well. But has RIT of NHL been (perhaps prematurely) left for dead by many? Given the current great clinical and commercial interest in radiopharmaceutical therapies of cancer, notably PSMA and SSTR targeting agents in prostate and neuroendocrine cancers, can radioimmunotherapy of NHL-like the mythical Phoenix-now rise from its ashes in an even better form to fly higher, faster, farther and longer than before?

Brain intratumoural astatine-211 radiotherapy targeting syndecan-1 leads to durable glioblastoma remission and immune memory in female mice.

BACKGROUND: Glioblastoma (GB), the most aggressive brain cancer, remains a critical clinical challenge due to its resistance to conventional treatments. Here, we introduce a locoregional targeted-α-therapy (TAT) with the rat monoclonal antibody 9E7.4 targeting murine syndecan-1 (SDC1) coupled to the α-emitter radionuclide astatine-211 (211At-9E7.4). METHODS: We orthotopically transplanted 50,000 GL261 cells of murine GB into the right striatum of syngeneic female C57BL/6JRj mice using stereotaxis. After MRI validation of tumour presence at day 11, TAT was injected at the same coordinates. Biodistribution, efficacy, toxicity, local and systemic responses were assessed following application of this protocol. The 9E7.4 monoclonal antibody was labelled with iodine-125 (125I) for biodistribution and with astatine-211 (211At) for the other experiments. FINDINGS: The 211At-9E7.4 TAT demonstrated robust efficacy in reducing orthotopic tumours and achieved improved survival rates in the C57BL/6JRj model, reaching up to 70% with a minimal activity of 100 kBq. Targeting SDC1 ensured the cerebral retention of 211At over an optimal time window, enabling low-activity administration with a minimal toxicity profile. Moreover, TAT substantially reduced the occurrence of secondary tumours and provided resistance to new tumour development after contralateral rechallenge, mediated through the activation of central and effector memory T cells. INTERPRETATION: The locoregional 211At-9E7.4 TAT stands as one of the most efficient TAT across all preclinical GB models. This study validates SDC1 as a pertinent therapeutic target for GB and underscores 211At-9E7.4 TAT as a promising advancement to improve the treatment and quality of life for patients with GB. FUNDING: This work was funded by the French National Agency for Research (ANR) "France 2030 Investment Plan" Labex Iron [ANR-11-LABX-18-01], The SIRIC ILIAD [INCa-DGOS-INSERM-18011], the French program "Infrastructure d'Avenir en Biologie-Santé" (France Life Imaging) [ANR-11-INBS-0006], the PIA3 of the ANR, integrated to the "France 2030 Investment Plan" [ANR-21-RHUS-0012], and support from Inviscan SAS (Strasbourg, France). It was also related to: the ANR under the frame of EuroNanoMed III (project GLIOSILK) [ANR-19-ENM3-0003-01]; the "Région Pays-de-la-Loire" under the frame of the Target'In project; the "Ligue Nationale contre le Cancer" and the "Comité Départemental de Maine-et-Loire de la Ligue contre le Cancer" (CD49) under the frame of the FusTarG project and the "Tumour targeting, imaging and radio-therapies network" of the "Cancéropôle Grand-Ouest" (France). This work was also funded by the Institut National de la Santé et de la Recherche Médicale (INSERM), the University of Nantes, and the University of Angers.

Development of 225Ac-doped biocompatible nanoparticles for targeted alpha therapy.

Targeted alpha therapy (TAT) relies on chemical affinity or active targeting using radioimmunoconjugates as strategies to deliver α-emitting radionuclides to cancerous tissue. These strategies can be affected by transmetalation of the parent radionuclide by competing ions in vivo and the bond-breaking recoil energy of decay daughters. The retention of α-emitting radionuclides and the dose delivered to cancer cells are influenced by these processes. Encapsulating α-emitting radionuclides within nanoparticles can help overcome many of these challenges. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles are a biodegradable and biocompatible delivery platform that has been used for drug delivery. In this study, PLGA nanoparticles are utilized for encapsulation and retention of actinium-225 ([225Ac]Ac3+). Encapsulation of [225Ac]Ac3+ within PLGA nanoparticles (Zave = 155.3 nm) was achieved by adapting a double-emulsion solvent evaporation method. The encapsulation efficiency was affected by both the solvent conditions and the chelation of [225Ac]Ac3+. Chelation of [225Ac]Ac3+ to a lipophilic 2,9-bis-lactam-1,10-phenanthroline ligand ([225Ac]AcBLPhen) significantly decreased its release (< 2%) and that of its decay daughters (< 50%) from PLGA nanoparticles. PLGA nanoparticles encapsulating [225Ac]AcBLPhen significantly increased the delivery of [225Ac]Ac3+ to murine (E0771) and human (MCF-7 and MDA-MB-231) breast cancer cells with a concomitant increase in cell death over free [225Ac]Ac3+ in solution. These results demonstrate that PLGA nanoparticles have potential as radionuclide delivery platforms for TAT to advance precision radiotherapy for cancer. In addition, this technology offers an alternative use for ligands with poor aqueous solubility, low stability, or low affinity, allowing them to be repurposed for TAT by encapsulation within PLGA nanoparticles.

Gene Abnormalities and Modulated Gene Expression Associated with Radionuclide Treatment: Towards Predictive Biomarkers of Response.

Molecular radiotherapy (MRT), also known as radioimmunotherapy or targeted radiotherapy, is the delivery of radionuclides to tumours by targeting receptors overexpressed on the cancer cell. Currently it is used in the treatment of a few cancer types including lymphoma, neuroendocrine, and prostate cancer. Recently reported outcomes demonstrating improvements in patient survival have led to an upsurge in interest in MRT particularly for the treatment of prostate cancer. Unfortunately, between 30% and 40% of patients do not respond. Further normal tissue exposure, especially kidney and salivary gland due to receptor expression, result in toxicity, including dry mouth. Predictive biomarkers to select patients who will benefit from MRT are crucial. Whilst pre-treatment imaging with imaging versions of the therapeutic agents is useful in demonstrating tumour binding and potentially organ toxicity, they do not necessarily predict patient benefit, which is dependent on tumour radiosensitivity. Transcript-based biomarkers have proven useful in tailoring external beam radiotherapy and adjuvant treatment. However, few studies have attempted to derive signatures for MRT response prediction. Here, transcriptomic studies that have identified genes associated with clinical radionuclide exposure have been reviewed. These studies will provide potential features for seeding multi-component biomarkers of MRT response.

Engineered Antibodies as Cancer Radiotheranostics.

Radiotheranostics is a rapidly growing approach in personalized medicine, merging diagnostic imaging and targeted radiotherapy to allow for the precise detection and treatment of diseases, notably cancer. Radiolabeled antibodies have become indispensable tools in the field of cancer theranostics due to their high specificity and affinity for cancer-associated antigens, which allows for accurate targeting with minimal impact on surrounding healthy tissues, enhancing therapeutic efficacy while reducing side effects, immune-modulating ability, and versatility and flexibility in engineering and conjugation. However, there are inherent limitations in using antibodies as a platform for radiopharmaceuticals due to their natural activities within the immune system, large size preventing effective tumor penetration, and relatively long half-life with concerns for prolonged radioactivity exposure. Antibody engineering can solve these challenges while preserving the many advantages of the immunoglobulin framework. In this review, the goal is to give a general overview of antibody engineering and design for tumor radiotheranostics. Particularly, the four ways that antibody engineering is applied to enhance radioimmunoconjugates: pharmacokinetics optimization, site-specific bioconjugation, modulation of Fc interactions, and bispecific construct creation are discussed. The radionuclide choices for designed antibody radionuclide conjugates and conjugation techniques and future directions for antibody radionuclide conjugate innovation and advancement are also discussed.

Rare Earth Nanoprobes for Targeted Delineation of Triple Negative Breast Cancer and Enhancement of Radioimmunotherapy.

Radiotherapy demonstrates a synergistic effect with immunotherapy by inducing a transformation of "immune cold" tumors into "immune hot" tumors in triple negative breast cancer (TNBC). Nevertheless, the effectiveness of immunotherapy is constrained by low expression of tumor-exposed antigens, inadequate inflammation, and insufficient tumor infiltrating lymphocyte (TILs). To address this predicament, novel lutecium-based rare earth nanoparticles (RENPs) are synthesized with the aim of amplifying radiation effect and tumor immune response. The nanoprobe is characterized by neodymium-based down-conversion fluorescence, demonstrating robust photostability, biocompatibility, and targetability. The conjugation of RENPs with a CXCR4 targeted drug enables precise delineation of breast tumors using a near-infrared imaging system and improves radiation efficacy via lutetium-based radio-sensitizer in vivo. Furthermore, the study shows a notable enhancement of immune response through the induction of immunogenic cell death and recruitment of TILs, resulting in the inhibition of tumor progression both in vitro and in vivo models following the administration of nanoparticles. Hence, the novel multifunctional nanoprobes incorporating various lanthanide elements offer the potential for imaging-guided tumor delineation, radio-sensitization, and immune activation post-radiation, thus presenting an efficient radio-immunotherapeutic approach for TNBC.

An Engineered Nanoplatform with Tropism Toward Irradiated Glioblastoma Augments Its Radioimmunotherapy Efficacy.

Combining radiotherapy with immune checkpoint blockade therapy offers a promising approach to treat glioblastoma multiforme (GBM), yet challenges such as limited effectiveness and immune-related adverse events (irAEs) persist. These issues are largely due to the failure in targeting immunomodulators directly to the tumor microenvironment. To address this, a biomimetic nanoplatform that combines a genetically modified mesenchymal stem cell (MSC) membrane with a bioactive nanoparticle core for chemokine-directed radioimmunotherapy of GBM is developed. The CC chemokine receptor 2 (CCR2)-overexpressing MSC membrane acts as a tactical tentacle to achieve radiation-induced tropism toward the abundant chemokine (CC motif) ligand 2 (CCL2) in irradiated gliomas. The nanoparticle core, comprising diselenide-bridged mesoporous silica nanoparticles (MSNs) and PD-L1 antibodies (αPD-L1), enables X-ray-responsive drug release and radiosensitization. In two murine models with orthotopic GBM tumors, this nanoplatform reinvigorated immunogenic cell death, and augmented the efficacy and specificity of GBM radioimmunotherapy, with reduced occurrence of irAEs. This study suggests a promising radiation-induced tropism strategy for targeted drug delivery, and presents a potent nanoplatform that enhances the efficacy and safety of radio-immunotherapy.

DLL3-guided therapies in small-cell lung cancer: from antibody-drug conjugate to precision immunotherapy and radioimmunotherapy.

DLL3 acts as an inhibitory ligand that downregulates Notch signaling and is upregulated by ASCL1, a transcription factor prevalent in the small-cell lung cancer (SCLC) subtype SCLC-A. Currently, the therapeutic strategies targeting DLL3 are varied, including antibody-drug conjugates (ADCs), bispecific T-cell engagers (BiTEs), and chimeric antigen receptor (CAR) T-cell therapies. Although rovalpituzumab tesirine (Rova-T) showed promise in a phase II study, it failed to produce favorable results in subsequent phase III trials, leading to the cessation of its development. Conversely, DLL3-targeted BiTEs have garnered significant clinical interest. Tarlatamab, for instance, demonstrated enhanced response rates and progression-free survival compared to the standard of care in a phase II trial; its biologics license application (BLA) is currently under US Food and Drug Administration (FDA) review. Numerous ongoing phase III studies aim to further evaluate tarlatamab's clinical efficacy, alongside the development of novel DLL3-targeted T-cell engagers, both bispecific and trispecific. CAR-T cell therapies targeting DLL3 have recently emerged and are undergoing various preclinical and early-phase clinical studies. Additionally, preclinical studies have shown promising efficacy for DLL3-targeted radiotherapy, which employs ß-particle-emitting therapeutic radioisotopes conjugated to DLL3-targeting antibodies. DLL3-targeted therapies hold substantial potential for SCLC management. Future clinical trials will be crucial for comparing treatment outcomes among various approaches and exploring combination therapies to improve patient survival outcomes.

Metabolic Regulation-Mediated Reversion of the Tumor Immunosuppressive Microenvironment for Potentiating Cooperative Metabolic Therapy and Immunotherapy.

Tumor cells exhibit heightened glucose (Glu) consumption and increased lactic acid (LA) production, resulting in the formation of an immunosuppressive tumor microenvironment (TME) that facilitates malignant proliferation and metastasis. In this study, we meticulously engineer an antitumor nanoplatform, denoted as ZLGCR, by incorporating glucose oxidase, LA oxidase, and CpG oligodeoxynucleotide into zeolitic imidazolate framework-8 that is camouflaged with a red blood cell membrane. Significantly, ZLGCR-mediated consumption of Glu and LA not only amplifies the effectiveness of metabolic therapy but also reverses the immunosuppressive TME, thereby enhancing the therapeutic outcomes of CpG-mediated antitumor immunotherapy. It is particularly important that the synergistic effect of metabolic therapy and immunotherapy is further augmented when combined with immune checkpoint blockade therapy. Consequently, this engineered antitumor nanoplatform will achieve a cooperative tumor-suppressive outcome through the modulation of metabolism and immune responses within the TME.

Alzheimer's Amyloid Hypothesis and Antibody Therapy: Melting Glaciers?

The amyloid cascade hypothesis for Alzheimer's disease is still alive, although heavily challenged. Effective anti-amyloid immunotherapy would confirm the hypothesis' claim that the protein amyloid-beta is the cause of the disease. Two antibodies, aducanumab and lecanemab, have been approved by the U.S. Food and Drug Administration, while a third, donanemab, is under review. The main argument for the FDA approvals is a presumed therapy-induced removal of cerebral amyloid deposits. Lecanemab and donanemab are also thought to cause some statistical delay in the determination of cognitive decline. However, clinical efficacy that is less than with conventional treatment, selection of amyloid-positive trial patients with non-specific amyloid-PET imaging, and uncertain therapy-induced removal of cerebral amyloids in clinical trials cast doubt on this anti-Alzheimer's antibody therapy and hence on the amyloid hypothesis, calling for a more thorough investigation of the negative impact of this type of therapy on the brain.

Defining D-irAEs: consensus-based disease definitions for the diagnosis of dermatologic adverse events from immune checkpoint inhibitor therapy.

With an increasing number of patients eligible for immune checkpoint inhibitors, the incidence of immune-related adverse events (irAEs) is on the rise. Dermatologic immune-related adverse events (D-irAEs) are the most common and earliest to manifest, often with important downstream consequences for the patient. Current guidelines lack clarity in terms of diagnostic criteria for D-irAEs. The goal of this project is to better define D-irAE for the purposes of identification, diagnosis, and future study of this important group of diseases.The objectives of this project were to develop consensus guidance for an approach to D-irAEs including disease definitions and severity grading. Knowing that consensus among oncologists, dermatologists, and irAE subspecialists would be critical for usability, we formed a Dermatologic irAE Disease Definition Panel. The panel was composed of 34 experts, including oncologists, dermatologists, a rheumatologist, and an allergist/immunologist from 22 institutions across the USA and internationally. A modified Delphi consensus process was used, with two rounds of anonymous ratings by panelists and two virtual meetings to discuss areas of controversy. Panelists rated content for usability, appropriateness, and accuracy on 9-point scales in electronic surveys and provided free text comments. A working group aggregated survey responses and incorporated them into revised definitions. Consensus was based on numeric ratings using the RAND/UCLA Appropriateness Method with prespecified definitions.Following revisions based on panelist feedback, all items received consensus in the second round of ratings. Consensus definitions were achieved for 10 core D-irAE diagnoses: ICI-vitiligo, ICI-lichen planus, ICI-psoriasis, ICI-exanthem, ICI-bullous pemphigoid, ICI-Grover's, ICI-eczematous, ICI-eruptive atypical squamous proliferation, ICI-pruritus without rash, and ICI-erosive mucocutaneous. A standard evaluation for D-irAE was also found to reach consensus, with disease-specific exceptions detailed when necessary. Each disorder's description includes further details on disease subtypes, symptoms, supportive exam findings, and three levels of diagnostic certainty (definite, probable, and possible).These consensus-driven disease definitions standardize D-irAE classification in a useable framework for multiple disciplines and will be the foundation for future work. Given consensus on their accuracy and usability from a representative panel group, we anticipate that they can be used broadly across clinical and research settings.

Perioperative immunotherapy for esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is the main prevalent histological subtype and accounts for 85% of esophageal cancer cases worldwide. Traditional treatment for ESCC involves chemotherapy, radiotherapy, and surgery. However, the overall prognosis remains unfavorable. Recently, immune checkpoint blockade (ICB) therapy using anti-programmed cell death-1 (PD-1)/PD-1 ligand (PD-L1) antibodies have not only achieved remarkable benefits in the clinical management of ESCC but have also completely changed the treatment approach for this cancer. In just a few years, ICB therapy has rapidly advanced and been added to standard first-line treatment regimen in patients with ESCC. However, preoperative immunotherapy is yet to be approved. In this review, we summarize the ICB antibodies commonly used in clinical immunotherapy of ESCC, and discuss the advances of immunotherapy combined with chemotherapy and radiotherapy in the perioperative treatment of ESCC, aiming to provide reference for clinical management of ESCC patients across the whole course of treatment.

Eradicating gross tumor disease: a prerequisite for efficient radioimmunotherapy?

Radiation therapy may induce off-target antitumor "abscopal" immunostimulatory and immunosuppressive effects. Several preclinical and early clinical studies revealed promising results when combining radiation therapy with immunostimulatory agents. Most radioimmunotherapy randomized trials showed disappointing results in patients with advanced tumors. In contrast, outcomes were encouraging when immunotherapy was delivered on top of gross disease elimination with curative-intent radiation therapy. In this review, we highlight available results from randomized trials and discuss the potential impact of overall tumor burden on the observed efficacy of radioimmunotherapy.

A T-Cell Inspired Sonoporation System Enhances Low-Dose X-Ray-Mediated Pyroptosis and Radioimmunotherapy Efficacy by Restoring Gasdermin-E Expression.

Genome editing has the potential to improve the unsatisfactory therapeutic effect of antitumor immunotherapy. However, the cell plasma membrane prevents the entry of almost all free genome-manipulation agents. Therefore, a system can be spatiotemporally controlled and can instantly open the cellular membrane to allow the entry of genome-editing agents into target cells is needed. Here, inspired by the ability of T cells to deliver cytotoxins to cancer cells by perforation, an ultrasound (US)-controlled perforation system (UPS) is established to enhance the delivery of free genome-manipulating agents. The UPS can perforate the tumor cell membrane while maintaining cell viability via a controllable lipid peroxidation reaction. In vitro, transmembrane-incapable plasmids can enter cells and perform genome editing with the assistance of UPS, achieving an efficiency of up to 90%. In vivo, the UPS is biodegradable, nonimmunogenic, and tumor-targeting, enabling the puncturing of tumor cells under US. With the application of UPS-assisted genome editing, gasdermin-E expression in 4T1 tumor-bearing mice is successfully restored, which leads to pyroptosis-mediated antitumor immunotherapy via low-dose X-ray irradiation. This study provides new insights for designing a sonoporation system for genome editing. Moreover, the results demonstrate that restoring gasdermin expression by genome editing significantly improves the efficacy of radioimmunotherapy.