Boosting the Abscopal Effect Using Immunogenic Biomaterials With Varying Radiation Therapy Field Sizes

Retrospective analysis and IMRT replanning of a 3D-CRT murine dose painting study for preclinical oxygen-guided radiotherapy

A recent parallel-opposed 3D-conformal radiotherapy (3D-CRT) study in mice compared dose escalation (boost) in hypoxic (pO2 ≤ 10 torr) and non-hypoxic tumor subvolumes. They found a hypoxic boost led to significantly greater (p < 1e-4) tumor control probability than an equivalent non-hypoxic boost. We imported imaging and treatment data from this study for 31 SCC7 squamous carcinoma murine leg tumor cases-16 hypoxic boost and 15 non-hypoxic boost plans into a commercial treatment planning system for preclinical radiotherapy. Treatments were retrospectively recalculated with a fast Monte Carlo dose engine. We replanned cases with 3-field IMRT using an analogous uncertainty budget as 3D-CRT. Comparing both treatment groups, the hypoxic boost treatments had a significantly higher hypoxic fraction receive the boost prescription as planned in 3D-CRT (p < 1e-4) and IMRT (p < 1e-4). Surprisingly, retrospective 3D-CRT non-hypoxic boost treatments had a significantly lower non-hypoxic fraction receive the boost prescription (p < 1e-4). 3D-CRT non-hypoxic boost also substantially underdosed the entire tumor between 48-68 Gy compared to the "equivalent" hypoxic boost. In IMRT, the non-hypoxic volume receiving boost prescription was significantly higher in the non-hypoxic boost (p = 0.0215) and dosing in the entire tumor was identical between boost groups. This study displays IMRT's potential to advance the quality of preclinical dose painting studies.

Aerosol Delivery of Hesperetin-Loaded Nanoparticles and Immunotherapy Increases Survival in a Murine Lung Cancer Model

Flavonoids, like Hesperetin, have been shown to be an ACE2 receptor agonists with antioxidant and pro-apoptotic activity and can induce apoptosis in cancer cells. ACE2 receptors are abundant in lung cancer cells. Here, we explored the application of Hesperetin bound to PegPLGA-coated nanoparticles (Hesperetin nanoparticles, HNPs) and anti-CD40 antibody as an aerosol treatment for lung tumor-bearing mice. The Hesperetin nanoparticles (HNPs) were engineered using a nano-formulation microfluidic technique and polymeric nanoparticles. The in vitro studies were performed in human A549 (ATCC) and murine LL/2-Luc2 (ATCC) lung cancer cell lines. A syngeneic orthotopic murine model of lung cancer was generated in wild (+/+) C57/BL6 background mice with luciferase-positive cell line LL/2-Luc2 cells. Lung tumor-bearing mice were treated via aerosol inhalation with HNP, anti-CD40 antibody, or both. Survival was used to analyze the efficacy of the aerosol treatment. The cohorts were also analyzed for body condition score, weight, and liver and kidney function. Analysis of an orthotopic murine lung cancer model demonstrated a differential uptake of the HNPs and anti-CD40 by the cancer cells. A higher survival rate was observed when the combination of aerosol treatment with HNPs was added with the treatment with anti-CD40 (p < 0.001), as compared to anti-CD40 alone (p < 0.01). Moreover, two tumor-bearing mice survived long-term with the combination treatment, and their tumors were diminished. Subsequently, these two mice were shown to be refractory to the development of subcutaneous tumors, indicating systemic resilience to developing new tumors. Using an inhalation-based administration, we successfully established a treatment model of increased therapeutic efficacy with HNPs and anti-CD40 in an orthotopic murine lung cancer model. Our findings open the possibility of improved lung cancer treatment using nanoparticles like flavonoids and immunoadjuvants.

Biomaterials enhancing localized cancer therapy activated anti-tumor immunity: a review

Localized cancer therapies such as radiotherapy, phototherapy, and chemotherapy are precise cancer treatment strategies aimed at minimizing systemic side effects. However, cancer metastasis remains the primary cause of mortality among cancer patients in clinical settings, and localized cancer treatments have limited efficacy against metastatic cancer. Therefore, researchers are exploring strategies that combine localized therapy with immunotherapy to activate robust anti-tumor immune responses, thereby eradicating metastatic cancer. Biomaterials, as novel materials, exhibit great potential in biomedical applications and have achieved great progress in clinic translation. This review introduces biomaterials and their applications in research focused on enhancing localized cancer treatment activated anti-tumor immunity. Additionally, the current challenges and future directions of biomaterials are also discussed, providing insights and references for related research.

PRIMERS: Polydopamine Radioimmunotherapy with Image-Guided Monitoring and Enhanced Release System

Background/Objectives: To overcome the side effects of conventional cancer treatment, multifunctional nanoparticles with image-guidance properties are increasingly desired to obtain enhanced therapeutic efficacy without any toxicity of the treatment. Herein, we introduce the potential of Polydopamine Radioimmunotherapy with Image-guided Monitoring and Enhanced (drug) Release System (PRIMERS) to meet the challenges of currently used cancer therapy. Methods: The PDA nanobowls were synthesized using an emulsion-induced interfacial anisotropic assembly method followed by surface modification with high-Z material to obtained the final product PRIMERS. Results: The engineered multifunctional nanosystem "PRIMERS" could serve as fiducial markers with the potential for use in combination cancer therapy. By leveraging the advantages of the excellent surface functionalization capability of PDA, the anisotropic nanostructure (PDA nanobowls) has been successfully functionalized with gadolinium, which shows strong MRI contrast signal both in vitro in phantom and in vivo in animals. The results of anti-cancer drug loading and releasing efficiency of these functionalized nanobowls are presented. Moreover, the gadolinium-coated PDA nanobowls demonstrate the capacity for loading immunotherapy drugs (Anti-CD40) with activated release in acidic pH levels characteristic of the tumor microenvironment, with enhanced release following administration of radiation therapy in vitro. Conclusions: Overall, the results highlight the potential of this new technology for combining radiotherapy with activated image-guided drug delivery, which offers broad opportunities to overcome current challenges in cancer treatment.

Immunologically effective biomaterials enhance immunotherapy of prostate cancer

Prostate cancer (PCa) is one of the most common malignant neoplasms affecting the male population. The onset of the disease is insidious and often associated with severe consequences, such as bone metastases at the time of initial diagnosis. Once it advances to metastatic castration-resistant PCa (mCRPC), conventional treatment methods become ineffective. As research on the mechanism of tumor therapy advances, immunotherapy has been evolving rapidly. However, PCa is a solid tumor type that primarily faces the challenges of poor immunogenicity and inhibitory tumor microenvironment (TME). Fortunately, the extensive use of biomaterials has led to continuous advancement in PCa immunotherapy. These innovative materials aim to address intractable issues, such as immune escape and immune desert, to inhibit tumor progression and metastasis. This detailed review focuses on the regulation of different aspects of tumor immunity by immunologically effective biomaterials, including modulating adaptive immunity, innate immunity, and the immune microenvironment, to enhance the efficacy of PCa immunotherapy. In addition, this review provides a perspective on the future prospects of immunotherapeutic nanoplatforms based on biomaterials in the treatment of PCa.

Aerosol delivery of immunotherapy and Hesperetin-loaded nanoparticles increases survival in a murine lung cancer model

Purpose

Studies have shown that flavonoids like Hesperetin, an ACE2 receptor agonist with antioxidant and pro-apoptotic activity, can induce apoptosis in cancer cells. ACE2 receptors are abundant in lung cancer cells. Here, we explored the application of Hesperetin bound to PLGA-coated nanoparticles (Hesperetin-nanoparticles, HNPs), and anti-CD40 antibody as an aerosol treatment for lung tumor-bearing mice.

Methods

In-vitro and in-vivo studies were performed in human A549 (ATCC) and murine LLC1 (ATCC) lung cancer cell lines. Hesperetin Nanoparticles (HNP) of about 60nm diameter were engineered using a nano-formulation microfluidic technique. A syngeneic orthotopic murine model of lung adenoma was generated in wild (+/+) C57/BL6 background mice with luciferase-positive cell line LLC1 cells. Lung tumor-bearing mice were treated via aerosol inhalation with HNP, anti-CD40 antibody, or both. Survival was used to analyze the efficacy of aerosol treatment. Cohorts were also analyzed for body condition score, weight, and liver and kidney function.

Results

Analysis of an orthotopic murine lung cancer model demonstrates a differential uptake of the HNP and anti-CD40 by cancer cells relative to normal cells. A higher survival rate, relative to untreated controls, was observed when aerosol treatment with HNP was added to treatment via anti-CD40 (p<0.001), as compared to CD40 alone (p<0.01). Moreover, 2 out of 9 tumor-bearing mice survived long term, and their tumors diminished. These 2 mice were shown to be refractory to subsequent development of subcutaneous tumors, indicating systemic resilience to tumor formation.

Conclusion

We successfully established increased therapeutic efficacy of anti-CD40 and HNP in an orthotopic murine lung cancer model using inhalation-based administration. Our findings open the possibility of improved lung cancer treatment using flavonoids and immuno-adjuvants.

Democratizing FLASH Radiotherapy

FLASH radiotherapy (RT) is emerging as a potentially revolutionary advancement in cancer treatment, offering the potential to deliver RT at ultra-high dose rates (>40 Gy/s) while significantly reducing damage to healthy tissues. Democratizing FLASH RT by making this cutting-edge approach more accessible and affordable for healthcare systems worldwide would have a substantial impact in global health. Here, we review recent developments in FLASH RT and present perspective on further developments that could facilitate the democratizing of FLASH RT. These include upgrading and validating current technologies that can deliver and measure the FLASH radiation dose with high accuracy and precision, establishing a deeper mechanistic understanding of the FLASH effect, and optimizing dose delivery conditions and parameters for different types of tumors and normal tissues, such as the dose rate, dose fractionation, and beam quality for high efficacy. Furthermore, we examine the potential for democratizing FLASH radioimmunotherapy leveraging evidence that FLASH RT can make the tumor microenvironment more immunogenic, and parallel developments in nanomedicine or use of smart radiotherapy biomaterials for combining RT and immunotherapy. We conclude that the democratization of FLASH radiotherapy represents a major opportunity for concerted cross-disciplinary research collaborations with potential for tremendous impact in reducing radiotherapy disparities and extending the cancer moonshot globally.

Investigating the Use of a Liquid Immunogenic Fiducial Eluter Biomaterial in Cervical Cancer Treatment

Globally, cervical cancer is the fourth leading cancer among women and is dominant in resource-poor settings in its occurrence and mortality. This study focuses on developing liquid immunogenic fiducial eluter (LIFE) Biomaterial with components that include biodegradable polymers, nanoparticles, and an immunoadjuvant. LIFE Biomaterial is designed to provide image guidance during radiotherapy similar to clinically used liquid fiducials while enhancing therapeutic efficacy for advanced cervical cancer. C57BL6 mice were used to grow subcutaneous tumors on bilateral flanks. The tumor on one flank was then treated using LIFE Biomaterial prepared with the immunoadjuvant anti-CD40, with/without radiotherapy at 6 Gy. Computed tomography (CT) and magnetic resonance (MR) imaging visibility were also evaluated in human cadavers. A pharmacodynamics study was also conducted to assess the safety of LIFE Biomaterial in healthy C57BL6 female mice. Results showed that LIFE Biomaterial could provide both CT and MR imaging contrast over time. Inhibition in tumor growth and prolonged significant survival (* p < 0.05) were consistently observed for groups treated with the combination of radiotherapy and LIFE Biomaterial, highlighting the potential for this strategy. Minimal toxicity was observed for healthy mice treated with LIFE Biomaterial with/without anti-CD40 in comparison to non-treated cohorts. The results demonstrate promise for the further development and clinical translation of this approach to enhance the survival and quality of life of patients with advanced cervical cancer.

Immune modulatory roles of radioimmunotherapy: biological principles and clinical prospects

Radiation therapy (RT) not only can directly kill tumor cells by causing DNA double-strand break, but also exerts anti-tumor effects through modulating local and systemic immune responses. The immunomodulatory effects of RT are generally considered as a double-edged sword. On the one hand, RT effectively enhances the immunogenicity of tumor cells, triggers type I interferon response, induces immunogenic cell death to activate immune cell function, increases the release of proinflammatory factors, and reshapes the tumor immune microenvironment, thereby positively promoting anti-tumor immune responses. On the other hand, RT stimulates tumor cells to express immunosuppressive cytokines, upregulates the function of inhibitory immune cells, leads to lymphocytopenia and depletion of immune effector cells, and thus negatively suppresses immune responses. Nonetheless, it is notable that RT has promising abscopal effects and may achieve potent synergistic effects, especially when combined with immunotherapy in the daily clinical practice. This systematic review will provide a comprehensive profile of the latest research progress with respect to the immunomodulatory effects of RT, as well as the abscopal effect of radioimmunotherapy combinations, from the perspective of biological basis and clinical practice.

Radiotherapy-Triggered In Situ Tumor Vaccination Boosts Checkpoint Blockaded Immune Response via Antigen-Capturing Nanoadjuvants

In situ vaccination (ISV) formed with the aid of intratumorally injected adjuvants has shed bright light on enhancing the abscopal therapeutic effects of radiotherapy. However, the limited availability of antigens resulting from the radiotherapy-induced immunogenic cell death largely hampers the clinical outcome of ISV. To maximally utilize the radiotherapy-induced antigen, we herein developed a strategy by capturing the radiotherapy-induced antigen in situ with a nanoadjuvant comprised of CpG-loaded Fe3O4 nanoparticles. The highly efficient click reaction between the maleimide residue on the nanoadjuvant and sulfhydryl group on the antigen maximized the bioavailability of autoantigens and CpG adjuvant in vivo. Importantly, combined immune checkpoint blockade can reverse T cell exhaustion after treatment with radiotherapy-induced ISV, thereby largely suppressing the treated and distant tumor. Mechanistically, metabolomics reveals the intratumorally injected nanoadjuvants disrupt redox homeostasis in the tumor microenvironment, further inducing tumor ferroptosis after radiotherapy. Overall, the current study highlights the immense potential of the innovative antigen-capturing nanoadjuvants for synergistically enhancing the antitumor effect.

Pre-Clinical Investigations of the Pharmacodynamics of Immunogenic Smart Radiotherapy Biomaterials (iSRB)

The use of an immunogenic smart radiotherapy biomaterial (iSRB) for the delivery of anti-CD40 is effective in treating different cancers in animal models. This study further characterizes the use of iSRBs to evaluate any associated toxicity in healthy C57BL6 mice. iSRBs were fabricated using a poly-lactic-co-glycolic-acid (PLGA) polymer mixed with titanium dioxide (TiO2) nanoparticles incorporated into its matrix. Animal studies included investigations of freely injected anti-CD40, anti-CD40-loaded iSRBs, unloaded iSRBs and control (healthy) animal cohorts. Mice were euthanized at pre-determined time points post-treatment to evaluate the serum chemistry pertaining to kidney and liver toxicity and cell blood count parameters, as well as pathology reports on organs of interest. Results showed comparable liver and kidney function in all cohorts. The results indicate that using iSRBs with or without anti-CD40 does not result in any significant toxicity compared to healthy untreated animals. The findings provide a useful reference for further studies aimed at optimizing the therapeutic efficacy and safety of iSRBs and further clinical translation work.

Smart Radiotherapy Biomaterials for Image-Guided In Situ Cancer Vaccination

Recent studies have highlighted the potential of smart radiotherapy biomaterials (SRBs) for combining radiotherapy and immunotherapy. These SRBs include smart fiducial markers and smart nanoparticles made with high atomic number materials that can provide requisite image contrast during radiotherapy, increase tumor immunogenicity, and provide sustained local delivery of immunotherapy. Here, we review the state-of-the-art in this area of research, the challenges and opportunities, with a focus on in situ vaccination to expand the role of radiotherapy in the treatment of both local and metastatic disease. A roadmap for clinical translation is outlined with a focus on specific cancers where such an approach is readily translatable or will have the highest impact. The potential of FLASH radiotherapy to synergize with SRBs is discussed including prospects for using SRBs in place of currently used inert radiotherapy biomaterials such as fiducial markers, or spacers. While the bulk of this review focuses on the last decade, in some cases, relevant foundational work extends as far back as the last two and half decades.

Trial watch: chemotherapy-induced immunogenic cell death in oncology

Immunogenic cell death (ICD) refers to an immunologically distinct process of regulated cell death that activates, rather than suppresses, innate and adaptive immune responses. Such responses culminate into T cell-driven immunity against antigens derived from dying cancer cells. The potency of ICD is dependent on the immunogenicity of dying cells as defined by the antigenicity of these cells and their ability to expose immunostimulatory molecules like damage-associated molecular patterns (DAMPs) and cytokines like type I interferons (IFNs). Moreover, it is crucial that the host's immune system can adequately detect the antigenicity and adjuvanticity of these dying cells. Over the years, several well-known chemotherapies have been validated as potent ICD inducers, including (but not limited to) anthracyclines, paclitaxels, and oxaliplatin. Such ICD-inducing chemotherapeutic drugs can serve as important combinatorial partners for anti-cancer immunotherapies against highly immuno-resistant tumors. In this Trial Watch, we describe current trends in the preclinical and clinical integration of ICD-inducing chemotherapy in the existing immuno-oncological paradigms.

Application of individualized multimodal radiotherapy combined with immunotherapy in metastatic tumors

Radiotherapy is one of the mainstays of cancer treatment. More than half of cancer patients receive radiation therapy. In addition to the well-known direct tumoricidal effect, radiotherapy has immunomodulatory properties. When combined with immunotherapy, radiotherapy, especially high-dose radiotherapy (HDRT), exert superior systemic effects on distal and unirradiated tumors, which is called abscopal effect. However, these effects are not always effective for cancer patients. Therefore, many studies have focused on exploring the optimized radiotherapy regimens to further enhance the antitumor immunity of HDRT and reduce its immunosuppressive effect. Several studies have shown that low-dose radiotherapy (LDRT) can effectively reprogram the tumor microenvironment, thereby potentially overcoming the immunosuppressive stroma induced by HDRT. However, bridging the gap between preclinical commitment and effective clinical delivery is challenging. In this review, we summarized the existing studies supporting the combined use of HDRT and LDRT to synergistically enhance antitumor immunity, and provided ideas for the individualized clinical application of multimodal radiotherapy (HDRT+LDRT) combined with immunotherapy.

A liquid immunogenic fiducial eluter for image-guided radiotherapy

Introduction

Fiducials are routinely used to provide image-guidance during radiotherapy. Here, a new nanoparticle-based liquid immunogenic fiducial is investigated for its potential to provide image-guidance, while also enhancing treatment outcomes.

Methods

This fiducial, liquid immunogenic fiducial eluter (LIFE) biomaterial, is formulated with natural biodegradable polymers, chitosan and sodium alginate with radio-sensitizing nanoparticles, and immunoadjuvant like anti-CD40 monoclonal antibody. Once administered intra-tumorally, this liquid smart radiotherapy biomaterial congeals within the calcium rich tumor microenvironment. The potential use of LIFE biomaterial for providing image guidance in magnetic resonance imaging (MRI) and computed tomography (CT) was investigated over different time period in a pre-clinical tumored mouse model.

Results

Results showed that the LIFE biomaterial can provide both MRI contrast and CT imaging contrast over 3-weeks, with gradual decrease of the contrast over time, as the LIFE biomaterial biodegrades. Results also showed the LIFE biomaterial significantly slowed tumor growth and prolonged mice survival (p < 0.0001) over time.

Discussion

The results highlight the potential use of the LIFE biomaterial as a multi-functional smart radiotherapy biomaterial that could be developed and optimized for hypo-fractionated radiotherapy applications and combining radiotherapy with immunoadjuvants.

Tumor-Specific Immunoenhancing Effects after Local Cryoablation for Metastatic Bone Tumor in a Mouse Model

We investigated the abscopal effect after cryoablation (CA) on bone metastasis using a mouse model. Breast cancer cells were implanted in the bilateral tibiae of mice. The left tumor was treated locally with CA, and the right abscopal tumor (AT) was left untreated. The mice were divided into four groups based on the combination of CA and intraperitoneal administration of anti-PD-1 antibody (PD) as treatment interventions (Control, CA, PD, and CA + PD). The reduction ratio of the size of AT, the quantitative immune effects at enzyme-linked immunospot (ELISPOT) assay, and the intensity of infiltration of immune-related cells to AT were compared among the groups. CA alone showed a significant immunoenhancing effect on the volume change ratio of AT from day 0 to day 14 (Control-CA: p < 0.05), ELISPOT assay (Control-CA: p < 0.01), and CD4+ cell count in immunostaining (Control-CA: p < 0.05). CA alone showed no significant immunoenhancing effect on CD8+ and Foxp3+ cell counts in immunostaining, but the combination of CA and PD showed a significant immunoenhancing effect (Control-CA + PD: p < 0.01 [CD8, Foxp3]). The results suggested that the abscopal effect associated with the local cryotherapy of metastatic bone tumors was activated by CA and enhanced by its combination with PD.

A ‘Hybrid’ Radiotherapy Regimen Designed for Immunomodulation: Combining High-Dose Radiotherapy with Low-Dose Radiotherapy

Simple Summary

Radiotherapy is an important cancer treatment. Aside from its direct killing effect, it also affects anti-tumor immunity. However, radiotherapy’s immune effect is not clear; it depends on the dose and fraction, cancer type, combined immunotherapy, and many other factors. Studies have focused on the optimal radiotherapy regimen to stimulate anti-tumor immunity, but conflicts exist, especially regarding the best radiation dose and fractions. Interestingly, high-dose radiotherapy and low-dose radiotherapy have complementary effects on stimulating anti-tumor immunity. Preclinical studies supporting this finding have accumulated, but gaps between theory and clinical practice still exist. This review summarizes the evidence supporting the use of this ‘hybrid’ radiotherapy approach to effectively stimulate anti-tumor immunity, explains the immune mechanisms of this combination, raises questions that must be addressed in clinical practice, and provides ideas for designing individualized treatment to increase efficiency in stimulating anti-tumor immunity using high-dose plus low-dose radiotherapy.

Abstract

Radiotherapy (RT) affects anti-tumor immunity. However, the exact impact of RT on anti-tumor immune response differs among cancer types, RT dose and fractions, patients’ innate immunity, and many other factors. There are conflicting findings on the optimal radiation dose and fractions to stimulate effective anti-tumor immunity. High-dose radiotherapy (HDRT) acts in the same way as a double-edged sword in stimulating anti-tumor immunity, while low-dose radiotherapy (LDRT) seems to play a vital role in modulating the tumor immune microenvironment. Recent preclinical data suggest that a ‘hybrid’ radiotherapy regimen, which refers to combining HDRT with LDRT, can reap the advantages of both. Clinical data have also indicated a promising potential. However, there are still questions to be addressed in order to put this novel combination therapy into clinical practice. For example, the selection of treatment site, treatment volume, the sequencing of high-dose radiotherapy and low-dose radiotherapy, combined immunotherapy, and so on. This review summarizes the current evidence supporting the use of HDRT + LDRT, explains possible immune biology mechanisms of this ‘hybrid’ radiotherapy, raises questions to be considered when working out individualized treatment plans, and lists possible avenues to increase efficiency in stimulating anti-tumor immunity using high-dose plus low-dose radiotherapy.