A Heterojunction Structured WO2.9-WSe2 Nanoradiosensitizer Increases Local Tumor Ablation and Checkpoint Blockade Immunotherapy upon Low Radiation Dose

Selenopeptide Nanomedicine Activates Natural Killer Cells for Enhanced Tumor Chemoimmunotherapy

Chemoimmunotherapy using nanotechnology has shown great potential for cancer therapy in the clinic. However, uncontrolled transportation and synergistic responses remain challenges. Here, a self-assembled selenopeptide nanoparticle that strengthens tumor chemoimmunotherapy through the activation of natural killer (NK) cells by the oxidative metabolite of the selenopeptide is developed. With the advantages of the enzyme-induced size-reduction and the reactive-oxygen-species-driven deselenization, this selenopeptide is able to deliver therapeutics, e.g., doxorubicin (DOX), to solid tumors and further activate the NK cells in a programmed manner. Importantly, in vitro and in vivo results prove the mutual promotion between the DOX-induced chemotherapy and the selenopeptide-induced immunotherapy, which synergistically contribute to the improved antitumor efficacy. It is anticipated that the selenopeptide may provide a type of promising stimuli-responsive immune modulator for versatile biomedical applications.

Multifunctional high-Z nanoradiosensitizers for multimodal synergistic cancer therapy

Radiotherapy (RT) is one of the most common and effective clinical therapies for malignant tumors. However, there are several limitations that undermine the clinical efficacy of cancer RT, including the low X-ray attenuation coefficient of organs, serious damage to normal tissues, and radioresistance in hypoxic tumors. With the rapid development of nanotechnology and nanomedicine, high-Z nanoradiosensitizers provide novel opportunities to overcome radioresistance and improve the efficacy of RT by deposition of radiation energy through photoelectric effects. To date, several types of nanoradiosensitizers have entered clinical trials. Nevertheless, the limitation of the single treatment mode and the unclear mechanism of nanoparticle radiosensitization have hindered the further development of nanoradiosensitizers. In this review, we systematically describe the interaction mechanisms between X-rays and nanomaterials and summarize recent advances in multifunctional high-Z nanomaterials for radiotherapeutic-based multimodal synergistic cancer therapy. Finally, the challenges and prospects are discussed to stimulate the development of nanomedicine-based cancer RT.

Reshaping the Tumor Immune Microenvironment Based on a Light-Activated Nanoplatform for Efficient Cancer Therapy

The immunosuppressive tumor microenvironment (TME) always causes poor antitumor immune efficacy, prone to relapse and metastasis. Herein, novel poly(vinylpyrrolidone) (PVP) modified BiFeO₃ /Bi₂ WO₆ (BFO/BWO) with a p-n type heterojunction is constructed for reshaping the immunosuppressive TME. Reactive oxygen species can be generated under light activation by the well-separated hole (h⁺ )-electron (e^- ) pairs owing to the heterojunction in BFO/BWO-PVP NPs. Interestingly, h⁺ can trigger the decomposition of H₂ O₂ to generate O₂ for alleviating tumor hypoxia, which not only sensitizes photodynamic therapy (PDT) and radiotherapy (RT), but also promotes tumor-associated macrophages (TAMs) polarization from M2 to M1 phenotype, which is beneficial to decrease the expression of HIF-1α. Importantly, such a light-activated nanoplatform, combining with RT can efficiently activate and recruit cytotoxic T lymphocytes to infiltrate in tumor tissues, as well as stimulate TAMs to M1 phenotype, dramatically reverse the immunosuppressive TME into an immunoactive one, and further boost immune memory responses. Moreover, BFO/BWO-PVP NPs also present high performance for computed tomography imaging contrast. Taken together, this work offers a novel paradigm for achieving O₂ self-supply of inorganic nanoagents and reshaping of the tumor immune microenvironment for effective inhibition of cancer as well as metastasis and recurrence.

Supramolecular Radiosensitizer Based on Hypoxia-Responsive Macrocycle

Radiotherapy (RT) has been viewed as one of the most effective and extensively applied curatives in clinical cancer therapy. However, the radioresistance of tumor severely discounts the radiotherapy outcomes. Here, an innovative supramolecular radiotherapy strategy, based on the complexation of a hypoxia-responsive macrocycle with small-molecule radiosensitizer, is reported. To exemplify this tactic, a carboxylated azocalix[4]arene (CAC4A) is devised as molecular container to quantitatively package tumor sensitizer banoxantrone dihydrochloride (AQ4N) through reversible host-guest interaction. Benefited from the selective reduction of azo functional groups under hypoxic microenvironment, the supramolecular prodrug CAC4A•AQ4N exhibits high tumor accumulation and efficient cellular internalization, thereby significantly amplifying radiation-mediated tumor destruction without appreciable systemic toxicity. More importantly, this supramolecular radiotherapy strategy achieves an ultrahigh sensitizer enhancement ratio (SER) value of 2.349, which is the supreme among currently reported noncovalent-based radiosensitization approach. Further development by applying different radiosensitizing drugs can make this supramolecular strategy become a general platform for boosting therapeutic effect in cancer radiotherapies, tremendously promising for clinical translation.

Development of nanotechnology-mediated precision radiotherapy for anti-metastasis and radioprotection

Radiotherapy (RT), including external beam RT and internal radiation therapy, uses high-energy ionizing radiation to kill tumor cells.

Shape-Controllable Tellurium-Driven Heterostructures with Activated Robust Immunomodulatory Potential for Highly Efficient Radiophotothermal Therapy of Colon Cancer

Tellurium (Te)-based semiconductor easily leads to the recombination of photogenerated electron-hole pairs (h⁺-e^-) that severely limits the efficiency of reactive oxygen species (ROS) generation and further hinders its clinical application in biomedicine. With regard to these problems, herein we designed and synthesized a Te heterostructure (BTe-Pd-Au) by incorporating palladium (Pd) and gold (Au) elements to promote its radiosensitivity and photothermal performance, thus realizing highly efficient radiophotothermal tumor elimination by activating robust immunomodulatory potential. This shape-controllable heterostructure that coated by Pd on the surface of Te nanorods and Au in the center of Te nanorods was simply synthesized by using in situ synthesis method, which could promote the generation and separation of h⁺-e^- pairs, thereby exhibiting superior ROS producing ability and photothermal conversion efficiency. Using a mouse model of colon cancer, we proved that BTe-Pd-Au-R-combined radiophotothermal therapy not only eradicated tumor but also elicited to a series of antitumor immune responses by enhancing the cytotoxic T lymphocytes, triggering dendritic cells maturation, and decreasing the percentage of M2 tumor-associated macrophages. In summary, our study highlights a facile strategy to design Te-driven heterostructure with versatile performance in radiosensitization, photothermal therapy, and immunomodulation and offers great promise for clinical translational treatment of colon cancer.

A multifunctional AIE gold cluster-based theranostic system: tumor-targeted imaging and Fenton reaction-assisted enhanced radiotherapy

BACKGROUND

As cancer is one of the main leading causes of mortality, a series of monotherapies such as chemotherapy, gene therapy and radiotherapy have been developed to overcome this thorny problem. However, a single treatment approach could not achieve satisfactory effect in many experimental explorations.

RESULTS

In this study, we report the fabrication of cyclic RGD peptide (cRGD) modified Au₄-iron oxide nanoparticle (Au₄-IO NP-cRGD) based on aggregation-induced emission (AIE) as a multifunctional theranostic system. Besides Au₄ cluster-based fluorescence imaging and enhanced radiotherapy, iron oxide (IO) nanocluster could realize magnetic resonance (MR) imaging and Fenton reaction-based chemotherapy. Abundant toxic reactive oxygen species generated from X-ray irradiation and in situ tumor-specific Fenton reaction under acidic microenvironment leads to the apoptotic and necrotic death of cancer cells. In vivo studies demonstrated good biocompatibility of Au₄-IO NP-cRGD and a high tumor suppression rate of 81.1% in the synergistic therapy group.

CONCLUSIONS

The successful dual-modal imaging and combined tumor therapy demonstrated AIE as a promising strategy for constructing multifunctional cancer theranostic platform.

Reeducating Tumor-Associated Macrophages Using CpG@Au Nanocomposites to Modulate Immunosuppressive Microenvironment for Improved Radio-Immunotherapy

With the recent success of immune checkpoint blockade (ICB) in cancer immunotherapy, there has been renewed interest in evaluating the combination of ICB inhibitors with radiotherapy (RT) in clinical trials in view of the localized RT-initiated vaccination effect, which can be augmented further by systemic immune-stimulating agents. Unfortunately, traditional RT/ICB accompanies severe toxicity from high-dose ionizing irradiation and low response rate from RT-aggravated immunosuppression, among which M2-type tumor-associated macrophages (TAMs) play an important role. Herein, CpG-decorated gold (Au) nanoparticles (CpG@Au NPs) were fabricated to improve the RT/ICB efficacy by immune modulation under low-dose X-ray exposure, where Au NPs served as radioenhancers to minimize the radiotoxicity, and yet acted as nanocarriers to deliver CpG, a toll-like receptor 9 agonist, to re-educate immunosuppressive M2 TAMs to immunostimulatory M1 counterparts, thus arousing innate immunity and meanwhile priming T cell activation. When combined with an anti-programmed death 1 antibody, irradiated CpG@Au led to consistent abscopal responses that efficiently suppressed distant tumors in a bilateral GL261 tumor-bearing model. This work thus demonstrates that CpG@Au-mediated macrophage reeducation could efficiently modulate the tumor-immune microenvironment for synergistic RT/ICB.

Redox-sensitive iodinated polymersomes carrying histone deacetylase inhibitor as a dual-functional nano-radiosensitizer for enhanced radiotherapy of breast cancer

Radiotherapy (RT) is a frequently used means in clinical tumor treatment. The outcome of RT varies, however, to a great extent, due to RT resistance or intolerable dose, which might be resolved by the development of radio-sensitizing strategies. Here, we report redox-sensitive iodinated polymersomes (RIP) carrying histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA, vorinostat), as a new dual-functional nano-radiosensitizer for breast cancer radiotherapy. SAHA-loaded RIP (RIP-SAHA) with a size of about 101 nm exhibited good colloidal stability while the reduction-activated release of SAHA, giving rise to better antitumor effect to 4T1 breast carcinoma cells than free SAHA. Accordingly, RIP-SAHA combined with a 4 Gy dose of X-ray radiation led to significantly enhanced suppression of 4T1 cells compared with SAHA combined 4 Gy of X-ray radiation, as a result of enhanced DNA damage and impeded DNA damage repair. The pharmacokinetics and biodistribution studies by single-photon emission computed tomography (SPECT) with ¹²⁵I-labeled SAHA (¹²⁵I-SAHA) showed a 17.3-fold longer circulation and 237.7-fold better tumor accumulation of RIP-SAHA over SAHA. The systemic administration of RIP-SAHA greatly sensitized radiotherapy of subcutaneous 4T1 breast tumors and brought about significant inhibition of tumor growth, without causing damages to major organs, compared with radiotherapy alone. RIP not only enhanced SAHA delivery but also acted as a radiosensitizer. RIP-SAHA emerges as a smart dual-functional nano-radiosensitizer to effectively enhance tumor radiotherapy.

Recent Advances in 2D Material-Mediated Immuno-Combined Cancer Therapy

In the last years, cancer immunotherapy has started to attract a lot of attention, becoming one of the alternatives in the clinical treatment of cancer. Indeed, one of the advantages of immunotherapy is that both primary and distant tumors can be efficiently eradicated through a triggered immune response. Due to their large specific surface area and unique physicochemical properties, 2D materials have become popular in cancer immunotherapy, especially as efficient drug carriers. They have been also exploited as photothermal platforms, chemodynamic agents, and photosensitizers to further enhance the efficacy of the therapy. In this review, the focus is on the recent development of 2D materials as new tools to combine immunotherapy with chemotherapy, photothermal therapy, photodynamic therapy, chemodynamic therapy, radiotherapy, and radiodynamic therapy. These innovative synergistic approaches intend to go beyond the classical strategies based on a simple delivery function of immune modulators by nanomaterials. Furthermore, the effects of the 2D materials themselves and their surface properties (e.g., chemical modification and protein corona formation) on the induction of an immune response will be also discussed.

Nanomedicine potentiates mild photothermal therapy for tumor ablation

The booming photothermal therapy (PTT) has achieved great progress in non-invasive oncotherapy, and paves a novel way for clinical oncotherapy. Of note, mild temperature PTT (mPTT) of 42–45 °C could avoid treatment bottleneck of the traditional PTT, including nonspecific injury to normal tissues, vasculature and host antitumor immunity. However, cancer cells can resist mPTT via heat shock response and autophagy, thus leading to insufficient mPTT monotherapy to ablate tumor. To overcome the deficient antitumor efficacy caused by thermo-resistance of cancer cells and mono mPTT, synergistic therapies towards cancer cells have been conducted with mPTT. This review summarizes the recent advances in nanomedicine-potentiated mPTT for cancer treatment, including strategies for enhanced single-mode mPTT and mPTT plus synergistic therapies. Moreover, challenges and prospects for clinical translation of nanomedicine-potentiated mPTT are discussed.

Immunogenic Cell Death Induced by Chemoradiotherapy of Novel pH-Sensitive Cargo-Loaded Polymersomes in Glioblastoma

Background

Inducing the immunogenic cell death of tumour cells can mediate the occurrence of antitumour immune responses and make the therapeutic effect more significant. Therefore, the development of treatments that can induce ICD to destroy tumour cells most effectively is promising. Previously, a new type of pH-sensitive polymersome was designed for the treatment of glioblastoma which represents a promising nanoplatform for future translational research in glioblastoma therapy. In this study, the aim of this work was to analyse whether chemoradiotherapy of the novel pH-sensitive cargo-loaded polymersomes can induce ICD.

Methods

Cell death in U87-MG and G422 cells was induced by Au-DOX@PO-ANG, and cell death was analysed by CCK-8 and flow cytometry. The release of CRT was determined by using laser scanning confocal microscopy and flow cytometry. ELISA kits were used to detect the release of HMGB1 and ATP. The dying cancer cells treated with different treatments were cocultured with bone-marrow-derived dendritic cells (BMDCs), and then flow cytometry was used to determine the maturation rate of BMDCs (CD11c+CD86+CD80+) to analyse the in vitro immunogenicity. Tumour vaccination experiments were used to evaluate the ability of Au-DOX@PO-ANG to induce ICD in vivo.

Results

We determined the optimal treatment strategy to evaluate the ability of chemotherapy combined with radiotherapy to induce ICD and dying cancer cells induced by Au-DOX@PO-ANG+RT could induce calreticulin eversion to the cell membrane, promote the release of HMGB1 and ATP, and induce the maturation of BMDCs. Using dying cancer cells induced by Au-DOX@PO-ANG+RT, we demonstrate the efficient vaccination potential of ICD in vivo.

Conclusion

These results identify Au-DOX@PO-ANG as a novel immunogenic cell death inducer in vitro and in vivo that could be effectively combined with RT in cancer therapy.

Immunogenic Cell Death Induction by Ionizing Radiation

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

Emerging strategies based on nanomaterials for ionizing radiation-optimized drug treatment of cancer

Drug-radiotherapy is a common and effective combinational treatment for cancer. This study aimed to explore the ionizing radiation-optimized drug treatment based on nanomaterials so as to improve the synergistic efficacy of drug-radiotherapy against cancer and limit the adverse effect on healthy organs. In this review, these emerging strategies were divided into four parts. First, the delivery of the drug-loaded nanoparticles was optimized owing to the strengthened passive targeting process, active targeting process, and cell targeting process of nanoparticles after ionizing radiation exposure. Second, nanomaterials were designed to respond to the ionizing radiation, thus leading to the release of the loading drugs controllably. Third, radiation-activated pro-drugs were loaded onto nanoparticles for radiation-triggered drug therapy. In particular, nontoxic nanoparticles with radiosensitization capability and innocuous radio-dynamic contrast agents can be considered as radiation-activated drugs, which were discussed in this review. Fourth, according to the various synergetic mechanisms, radiotherapy could improve the drug response of cancer, obtaining optimized drug-radiotherapy. Finally, relative suggestions were provided to further optimize these aforementioned strategies. Therefore, a novel topic was selected and the emerging strategies in this region were discussed, aiming to stimulate the inspiration for the development of ionizing radiation-optimized drug treatment based on nanomaterials.

Tumor Microenvironment-Activated Nanoparticles Loaded with an Iron-Carbonyl Complex for Chemodynamic Immunotherapy of Lung Metastasis of Melanoma In Vivo

In this work, a nanoplatform (FeCORM NPs) loaded with an iron-carbonyl complex was constructed. By exploiting chemodynamic therapy (CDT) and immunogenic cell death (ICD)-induced immunotherapy (IMT), the nanoparticles exhibited excellent efficacy against lung metastasis of melanoma in vivo. The iron-carbonyl compound of the nanomaterials could be initiated by both glutathione (GSH) and hydrogen peroxide (H₂O₂) to release CO and generate ferrous iron through ligand exchange and oxidative destruction pathways. The released CO caused mitochondria damage, whereas the generated ferrous iron led to oxidative stress via the Fenton reaction. On the other hand, the nanomaterials induced ICD-based IMT, which worked jointly with CDT to exhibit excellent effects against lung metastasis of melanoma through a mouse model. This work demonstrated how a nanoplatform, simple and stable but showing excellent efficacy against tumors, could be built using simple building blocks via a self-assembling approach. Importantly, the system took advantage of relatively high levels of GSH and H₂O₂ in tumors to initiate the therapeutic effects, which rendered the nanoplatform with a capability to differentiate normal cells from tumor cells. In principle, the system has great potential for future clinical applications, not only in the treatment of lung metastasis of melanoma but also in suppressing other types of tumors.

Rediscovery of nanoparticle-based therapeutics: boosting immunogenic cell death for potential application in cancer immunotherapy

Immunogenic cell death (ICD) occurring by chemical and physical stimuli has shown the potential to activate an adaptive immune response in the immune-competent living body through the release of danger-associated molecular patterns (DAMPs) into the tumor microenvironment (TME). However, limitations to the long-term immune responses and systemic toxicity of conventional ICD inducers have led to unsatisfactory therapeutic efficacy in ICD-based cancer immunotherapy. Until now, various nanoparticle-based ICD-inducers have been developed to induce an antitumor immune response without severe toxicity, and to efficiently elicit an anticancer immune response against target cancer cells. In this review, we introduce a recent advance in the designs and applications of nanoparticle-based therapeutics to elicit ICD for effective cancer immunotherapy. In particular, combination strategies of nanoparticle-based ICD inducers with typical theranostic modalities are introduced intensively. Subsequently, we discuss the expected challenges and future direction of nanoparticle-based ICD inducers to provide strategies for boosting ICD in cancer immunotherapy. These versatile designs and applications of nanoparticle-based therapeutics for ICD can provide advantages to improve the therapeutic efficacy of cancer immunotherapy.

NIR-Triggered Multi-Mode Antitumor Therapy Based on Bi2 Se3 /Au Heterostructure with Enhanced Efficacy

Of all the reaction oxygen species (ROS) therapeutic strategies, NIR light-induced photocatalytic therapy (PCT) based on semiconductor nanomaterials has attracted increasing attention. However, the photocatalysts suffer from rapid recombination of electron-hole pairs due to the narrow band gaps, which are greatly restricted in PCT application. Herein, Bi₂ Se₃ /Au heterostructured photocatalysts are fabricated to solve the problems by introducing Au nanoparticles (NPs) in situ on the surface of the hollow mesoporous structured Bi₂ Se₃ . Owing to the lower work function of Au NPs, the photo-induced electrons are easier to transfer and assemble on their surfaces, resulting in the increased separation of the electron-hole pairs with efficient ROS generation. Besides, Bi₂ Se₃ /Au heterostructures also enhance the photothermal efficiency due to the effective orbital overlaps with accelerated electron migrations according to density functional theory calculations. Moreover, the PLGA-PEG and the doxorubicin (DOX) are introduced for photothermal-triggered drug release in the system. The Bi₂ Se₃ /Au heterostructures also displays excellent infrared thermal (IRT) and computed tomography (CT) dual-modal imaging property for promising cancer diagnosis. Collectively, Bi₂ Se₃ /Au@PLGA-PEG-DOX exhibits prominent tumor inhibition effect based on synchronous PTT, PCT and chemotherapy triggered by NIR light for efficient antitumor treatment.

Tumor microenvironment-triggered in situ cancer vaccines inducing dual immunogenic cell death for elevated antitumor and antimetastatic therapy

Cancer vaccines are made from tumor-specific antigens, which are then injected back into the body to activate immune responses for cancer immunotherapy. Despite the high specificity and therapeutic efficiency, the vaccine has huge challenges such as complex preparation process, expensiveness and limited durational effects. Herein, a strategy to develop in situ cancer vaccines by enhancing the immunomodulatory effects for immunogenic cell death (ICD) is presented. First, amorphous iron oxide-packaged oxaliplatin (AIOoxp) nanoprodrugs with a high drug loading efficiency of 12.9% were prepared. By utilizing tumor microenvironment (TME) as an endogenous stimulus, this inorganic nanoprodrug can effectively realize TME-responsive combined treatments of chemotherapy and chemodynamic therapy (CDT), and thus achieve dual and precise ICD induction. Further, in vivo immunopotentiation performances further prove that this enhanced ICD effect is able to efficiently promote the maturity of dendritic cells (DCs), T cell activation and correlative cytokine secretion. Furthermore, the obtained nanoprodrugs not only reduce systemic toxicities of Oxp and achieve T1/T2 magnetic resonance imaging (MRI), but also dramatically inhibit tumor growth and lung metastasis. We believe that the design of in situ cancer vaccines by enhancing the ICD effects will inspire future studies on cancer vaccines.

Nanobiotechnology-enabled energy utilization elevation for augmenting minimally-invasive and noninvasive oncology thermal ablation

Depending on the local or targeted treatment, independence on tumor type and minimally-invasive and noninvasive feature, various thermal ablation technologies have been established, but they still suffer from the intractable paradox between safety and efficacy. It has been extensively accepted that improving energy utilization efficiency is the primary means of decreasing thermal ablation power and shortening ablation time, which is beneficial for concurrently improving both treatment safety and treatment efficiency. Recent efforts have been made to receive a significant advance in various thermal methods including non-invasive high-intensity focused ultrasound, minimally-invasive radiofrequency and microwave, and non-invasive and minimally-invasive photothermal ablation, and so on. Especially, various nanobiotechnologies and design methodologies were employed to elevate the energy utilization efficiency for acquiring unexpected ablation outcomes accompanied with tremendously reduced power and time. More significantly, some combined technologies, for example, chemotherapy, photodynamic therapy (PDT), gaseous therapy, sonodynamic therapy (SDT), immunotherapy, chemodynamic therapy (CDT), or catalytic nanomedicine, were used to assist these ablation means to repress or completely remove tumors. We discussed and summarized the ablation principles and energy transformation pathways of the four ablation means, and reviewed and commented the progress in this field including newly developed technology or new material types with a highlight on nanobiotechnology-inspired design principles, and provided the deep insights into the existing problems and development direction. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Nano-enabled coordination platform of bismuth nitrate and cisplatin prodrug potentiates cancer chemoradiotherapy via DNA damage enhancement

The combination of chemotherapy and radiotherapy (chemoradiotherapy) is a promising strategy, extensively studied and applied clinically. Meanwhile, radiosensitizers play an important role in improving clinical radiotherapy therapeutic efficacy. There are still some disadvantages in practical applications, because radiosensitizers and drugs are difficult to deliver spatio-temporally to tumor sites and work simultaneously with low efficiency for DNA damage and repair inhibition, leading to an inferior synergistic effect. Herein, a suitable radiosensitizer of nano-enabled coordination platform (NP@PVP) with bismuth nitrate and cisplatin prodrug is developed by a simple synthetic route to improve the effectiveness of chemo-radiation synergistic therapy. When NP@PVP is internalized by a tumor cell, the bismuth in NP@PVP can sensitize radiation therapy (RT) by increasing the amount of reactive oxygen species generation to enhance DNA damage after X-ray radiation; meanwhile, the cisplatin in NP@PVP can inhibit DNA damage repair with spatio-temporal synchronization. NP@PVP is demonstrated to exhibit higher sensitization enhancement ratio (SER) of 2.29 and excellent tumor ablation capability upon irradiation in vivo in comparison with cisplatin (SER of 1.78). Our strategy demonstrates that the RT sensitization effect of bismuth and cisplatin based NP@PVP has great anticancer potential in chemo-radiation synergistic therapy, which is promising for clinical application.

Low-Temperature Photothermal Therapy: Strategies and Applications

Although photothermal therapy (PTT) with the assistance of nanotechnology has been considered as an indispensable strategy in the biomedical field, it still encounters some severe problems that need to be solved. Excessive heat can induce treated cells to develop thermal resistance, and thus, the efficacy of PTT may be dramatically decreased. In the meantime, the uncontrollable diffusion of heat can pose a threat to the surrounding healthy tissues. Recently, low-temperature PTT (also known as mild PTT or mild-temperature PTT) has demonstrated its remarkable capacity of conquering these obstacles and has shown excellent performance in bacterial elimination, wound healing, and cancer treatments. Herein, we summarize the recently proposed strategies for achieving low-temperature PTT based on nanomaterials and introduce the synthesis, characteristics, and applications of these nanoplatforms. Additionally, the combination of PTT and other therapeutic modalities for defeating cancers and the synergistic cancer therapeutic effect of the combined treatments are discussed. Finally, the current limitations and future directions are proposed for inspiring more researchers to make contributions to promoting low-temperature PTT toward more successful preclinical and clinical disease treatments.

The synergistic strategies for the immuno-oncotherapy with photothermal nanoagents

Immuno-oncotherapy has shown great promise for the cure of late-stage and metastatic cancer. Great efforts have tried to improve the overall response rate (ORR) and to reduce the immune-related adverse events (irAEs). Antigen presentation, T cell activation and killing are interlocking and distinct steps to initiate effective anti-tumor immune responses. Aiming to overcome the tumor immune evasion whose mechanisms include limited release of neoantigen, suppressed infiltration of antigen-presenting cells (APCs) and T cells, and the expression of immune checkpoints (ICPs), combinational therapeutic strategies have shown great potential by activating the anti-tumor immune responses together with deactivating immunosuppressive conditions simultaneously. In this direction, photothermal therapy (PTT) has attracted attention due to the efficient ablation of tumor cells, of which the released immunogenic tumor debris can activate host immune responses. The combination of immunoadjuvants and/or ICP inhibitors can boost the anti-tumor immune responses, realizing PTT-synergized immuno-oncotherapy. In this regard, numerous multifunctional nanomaterials have been designed with integration of photothermal and immuno-oncotherapeutic agents into one package via well-designed surface modification and functionalization. This review summarizes the recent studies on the synergistic strategies for the immuno-oncotherapy based on photothermal nanoagents and the mechanisms that trigger the systemic anti-tumor immune responses and PTT-synergized immuno-oncotherapy. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

BiVO4/Fe3O4@polydopamine superparticles for tumor multimodal imaging and synergistic therapy

Background

Despite tremendous progress has been achieved in tumor theranostic over the past decade, accurate identification and complete eradication of tumor cells remain a great challenge owing to the limitation of single imaging modality and therapeutic strategy.

Results

Herein, we successfully design and construct BiVO₄/Fe₃O₄@polydopamine (PDA) superparticles (SPs) for computed tomography (CT)/photoacoustic (PA)/magnetic resonance (MR) multimodal imaging and radiotherapy (RT)/photothermal therapy (PTT) synergistic therapy toward oral epithelial carcinoma. On the one hand, BiVO₄ NPs endow BiVO₄/Fe₃O₄@PDA SPs with impressive X-ray absorption capability due to the high X-ray attenuation coefficient of Bi, which is beneficial for their utilization as radiosensitizers for CT imaging and RT. On the other hand, Fe₃O₄ NPs impart BiVO₄/Fe₃O₄@PDA SPs with the superparamagnetic property as a T₂-weighted contrast agent for MR imaging. Importantly, the aggregation of Fe₃O₄ NPs in SPs and the presence of PDA shell greatly improve the photothermal conversion capability of SPs, making BiVO₄/Fe₃O₄@PDA SPs as an ideal photothermal transducer for PA imaging and PTT. By integrating advantages of various imaging modalities (CT/PA/MR) and therapeutic strategies (RT/PTT), our BiVO₄/Fe₃O₄@PDA SPs exhibit the sensitive multimodal imaging feature and superior synergistic therapeutic efficacy on tumors.

Conclusions

Since there are many kinds of building blocks with unique properties appropriating for self-assembly, our work may largely enrich the library of nanomateirals for tumor diagnosis and treatment.

Application of New Radiosensitizer Based on Nano-Biotechnology in the Treatment of Glioma

Glioma is the most common intracranial malignant tumor, and its specific pathogenesis has been unclear, which has always been an unresolved clinical problem due to the limited therapeutic window of glioma. As we all know, surgical resection, chemotherapy, and radiotherapy are the main treatment methods for glioma. With the development of clinical trials and traditional treatment techniques, radiotherapy for glioma has increasingly exposed defects in the treatment effect. In order to improve the bottleneck of radiotherapy for glioma, people have done a lot of work; among this, nano-radiosensitizers have offered a novel and potential treatment method. Compared with conventional radiotherapy, nanotechnology can overcome the blood–brain barrier and improve the sensitivity of glioma to radiotherapy. This paper focuses on the research progress of nano-radiosensitizers in radiotherapy for glioma.

Molybdenum disulfide-based materials with enzyme-like characteristics for biological applications

Nanozyme, a kind of nanomaterials with enzymatic activity, has been developing vigorously over the past years owing to its advantages such as low-cost, easy storage, ease of use in harsh environments and so on, compared with natural enzymes. At present, as a typical two-dimensional nanomaterial, molybdenum disulfide (MoS₂) and their hybrids with unexpected enzyme-like activities have caused wide attention. In this review, we mainly investigated the enzyme-like activities of MoS₂ based nanomaterials, including peroxidase-like activity, catalase-like activity and superoxide dismutase-like activity. Furthermore, we systematically introduce recent research progress of MoS₂ based nanomaterials in the fields of biological applications such as radiation protection, cancer therapy, antibacterial, and wound healing. Finally, the current challenges and perspectives of MoS₂ based nanomaterials in the future are also discussed and proposed. We expect this review may be significant to understand the properties of MoS₂ based nanomaterials and the development of two-dimensional nanomaterials with enzyme mimicking activities.

UCPs/Zn2GeO4:Mn2+/g-C3N4 heterojunction engineered injectable thermosensitive hydrogel for oxygen independent breast cancer neoadjuvant photodynamic therapy

Neoadjuvant chemotherapy for the treatment of breast cancer can provide the option of surgery for patients with a large tumor mass or increase the rate of breast conservation. However, some patients are not sensitive to chemotherapeutic drugs, and therefore this may cause them to miss their optimal chance for surgery. Herein, photodynamic therapy (PDT) was chosen instead of chemotherapy as a neoadjuvant treatment for breast cancer because of its effectiveness against different cancer cells and the lack of side effects in normal tissues. Considering the hypoxic environment of tumors and the tissue penetration depth, a heterojunction Zn₂GeO₄:Mn²⁺/g-C₃N₄ was designed and combined with upconversion materials NaYF₄:Yb³⁺, Tm³⁺ and hyaluronic acid to form a NaYF₄:Yb³⁺, Tm³⁺/Zn₂GeO₄:Mn²⁺/g-C₃N₄@HA (UZC@HA) photosensitizer. After intratumoral administration using a thermosensitive hydrogel as a carrier, under a 980 nm laser, UZC@HA can generate holes and electrons to oxidize water to form a hydroxyl radical (˙OH) and react with O₂ to produce the superoxide ion (˙O₂^-), respectively. The thermosensitive hydrogel not only supplies water, but also ensures the high loading capacity of UZC@HA. HA on the UZC can bind specifically with CD44R-overexpressing tumor cells and help the photosensitizer to target tumor sites. Thus, near infrared (NIR) mediated oxygen-independent PDT can be realized. After 12 d of treatment, the tumor mass was significantly reduced and no side effects in normal tissues were observed. Our work shows the potential of the NIR mediated heterojunction UZC@HA to act as a photosensitizer for neoadjuvant PDT in breast cancer and may open a new avenue for exploration of PDT and provide more options for breast cancer patients.

Immunogenicity of Externally Activated Nanoparticles for Cancer Therapy

Simple Summary

Recent advances in treating cancer via stimulating an anti-tumor immune system response have resulted in extraordinary results for lymphomas and leukemias; however these therapies have not performed well in solid tumors. External beam therapies, such as radiotherapy, hyperthermia, and photodynamic therapy, that are clinically used for solid tumors are now being explored in combination with nanoparticle systems to stimulate a long-term anti-tumor immune system response. In this review, we detail the novel nanoparticle complexes that are being researched to activate an anti-tumor immune response in combination with external beam therapy in both the preclinical and clinical settings.

Abstract

Nanoparticles activated by external beams, such as ionizing radiation, laser light, or magnetic fields, have attracted significant research interest as a possible modality for treating solid tumors. From producing hyperthermic conditions to generating reactive oxygen species, a wide range of externally activated mechanisms have been explored for producing cytotoxicity within tumors with high spatiotemporal control. To further improve tumoricidal effects, recent trends in the literature have focused on stimulating the immune system through externally activated treatment strategies that result in immunogenic cell death. By releasing inflammatory compounds known to initiate an immune response, treatment methods can take advantage of immune system pathways for a durable and robust systemic anti-tumor response. In this review, we discuss recent advancements in radiosensitizing and hyperthermic nanoparticles that have been tuned for promoting immunogenic cell death. Our review covers both preclinical and clinical results, as well as an overview of possible future work.

Hyperthermia Targeting the Tumor Microenvironment Facilitates Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) have ushered in a new era of cancer therapy; however, ICIs are only effective in selective patients. The efficacy of ICIs is closely related to the tumor microenvironment. Fever for a long time was thought to directly regulate the immune response, and artificial “fever” from hyperthermia modulates the tumor immune microenvironment by providing danger signals with heat shock proteins (HSPs) as well as subsequent activation of immune systems. Encouraging results have been achieved in preclinical studies focused on potential synergetic effects by combining hyperthermia with ICIs. In this review, we summarized a cluster of immune-related factors that not only make hyperthermia a treatment capable of defending against cancer but also make hyperthermia a reliable treatment that creates a type I-like tumor microenvironment (overexpression of PD-L1 and enrichment of tumor infiltrating lymphocytes) in complementary for the enhancement of the ICIs. Then we reviewed recent preclinical data of the combination regimens involving hyperthermia and ICIs that demonstrated the combined efficacy and illustrated possible approaches to further boost the effectiveness of this combination.

Palladium Nanosheets as Safe Radiosensitizers for Radiotherapy

Many noble metal-based nanoparticles have emerged for applications in cancer radiotherapy in recent years, but few investigations have been carried out for palladium nanoparticles. Herein, palladium nanosheets (Pd NSs), which possess a sheetlike morphology with a diameter of ∼14 nm and a thickness of ∼2 nm, were utilized as a sensitizer to improve the performance of radiotherapy. It was found that Pd NSs alone did not decrease the cell viability after treatment for as long as 130 h, suggesting the excellent cytocompatibility of the nanoagents. However, the viability of cancer cells treated with X-ray irradiation became lower, and the viability became even lower if the cells were co-treated with X-ray and Pd NSs, indicating the radiosensitization effect of Pd NSs. Additionally, compared with X-ray irradiation, the combined treatment of Pd NSs and X-ray irradiation induced the generation of more DNA double-stranded breaks and reactive oxygen species within cancer cells, which eventually caused elevated cell apoptosis. Moreover, in vivo experiments also verified the radiosensitization effect and the favorable biocompatibility of Pd NSs, indicating their potential for acquiring satisfactory in vivo radiotherapeutic effect at lower X-ray doses. It is believed that the present research will open new avenues for the application of noble metal-based nanoparticles in radiosensitization.

Magnetic nanoparticles coated with polyphenols for spatio-temporally controlled cancer photothermal/immunotherapy

As the combination of photothermal therapy (PTT) with immunotherapy provides an effective strategy in cancer treatment, a magnetic nanoparticle delivery system was constructed to load indocyanine green (ICG) and immunostimulator R837 hydrochloride (R837) for spatio-temporally PTT/immunotherapy synergism in cancer. This delivery system is composed of Fe₃O₄ magnetic nanoparticles (MPs) as the core to load ICG and polyethylene glycol polyphenols (DPA-PEG) as the coating layer to load R837, which formed R837 loaded polyphenols coating ICG loaded magnetic nanoparticles (MIRDs). After intravenous injection, the formed MIRDs resulted in long circulation, magnetic resonance imaging (MRI) guides, and magnetic targeting. Once targeting to the tumor, the MIRDs with the near-infrared (NIR) irradiation caused tumor ablation and resulted in tumor-associated antigens releasing to induce the body's immunological response, which was markedly improved it to attack the tumors with the R837 releasing from the outer DPA-PEG. In this case, the synergism of the PTT and immunotherapy inhibited tumor growth, metastasis and recurrence, which resulted in potent anticancer therapeutic effects with few side effect.