A Dual-Bioresponsive Drug-Delivery Depot for Combination of Epigenetic Modulation and Immune Checkpoint Blockade

Improving safety of cancer immunotherapy via delivery technology

Breakthroughs in molecular mechanisms underlying immune-suppressive tumor microenvironment and paradigm shifts in the cancer-immunity response cycle have profoundly changed the landscape of cancer immunotherapy. However, one of the challenges is to mitigate the serious side effects caused by systemic autoimmunity and autoinflammatory responses following immunotherapy. Thus, restraining the activation of the immune system in healthy tissues is highly desirable to address this problem. Bioengineering and delivery technologies provide a solution to the issue. In this Review, we first introduce immune-related adverse effects of main immunotherapies and the underlying mechanisms, summarize strategies of designingde bioengineering and delivery systems to reduce their immunotoxicities, and highlight the importance of the development of immunotoxicity-related animal models.

Advances in engineering local drug delivery systems for cancer immunotherapy

Cancer immunotherapy aims to leverage the immune system to suppress the growth of tumors and to inhibit metastasis. The recent promising clinical outcomes associated with cancer immunotherapy have prompted research and development efforts towards enhancing the efficacy of immune checkpoint blockade, cancer vaccines, cytokine therapy, and adoptive T cell therapy. Advancements in biomaterials, nanomedicine, and micro-/nano-technology have facilitated the development of enhanced local delivery systems for cancer immunotherapy, which can enhance treatment efficacy while minimizing toxicity. Furthermore, locally administered cancer therapies that combine immunotherapy with chemotherapy, radiotherapy, or phototherapy have the potential to achieve synergistic antitumor effects. Herein, the latest studies on local delivery systems for cancer immunotherapy are surveyed, with an emphasis on the therapeutic benefits associated with the design of biomaterials and nanomedicines. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Highly uniform self-assembled microspheres from single macromolecule self-recognition for enhanced cancer immunotherapy

Self-assembled highly uniform microspheres from star-shaped biocompatible polymers have been prepared as a local delivery system for co-loading different immunoagents together and ensuring their release in different stages, so as to realize effective cooperative immunotherapy and minimize systemic side effects.

Nanoparticle-hydrogel superstructures for biomedical applications

The incorporation of nanoparticles into hydrogels yields novel superstructures that have become increasingly popular in biomedical research. Each component of these nanoparticle-hydrogel superstructures can be easily modified, resulting in platforms that are highly tunable and inherently multifunctional. The advantages of the nanoparticle and hydrogel constituents can be synergistically combined, enabling these superstructures to excel in scenarios where employing each component separately may have suboptimal outcomes. In this review, the synthesis and fabrication of different nanoparticle-hydrogel superstructures are discussed, followed by an overview of their use in a range of applications, including drug delivery, detoxification, immune modulation, and tissue engineering. Overall, these platforms hold significant clinical potential, and it is envisioned that future development along these lines will lead to unique solutions for addressing areas of pressing medical need.

Converting Immune Cold into Hot by Biosynthetic Functional Vesicles to Boost Systematic Antitumor Immunity

Immune cold tumor characterized by low immunogenicity, insufficient and exhausted tumor-infiltrating lymphocytes, and immunosuppressive microenvironment is the main bottleneck responsible for low patient response rate of immune checkpoint blockade. Here, we developed biosynthetic functional vesicles (BFVs) to convert immune cold into hot through overcoming hypoxia, inducing immunogenic cell death, and immune checkpoint inhibition. The BFVs present PD1 and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on the surface, whereas load catalase into their inner core. The TRAIL can specifically induce immunogenic death of cancer cells to initiate immune response, which is further synergistically strengthened by blocking PD1/PDL1 checkpoint signal through ectogenic PD1 proteins on BFVs. The catalase can produce O2 to overcome tumor hypoxia, in turn to increase infiltration of effector T cells while deplete immunosuppressive cells in tumor. The BFVs elicit robust and systematic antitumor immunity, as demonstrated by significant regression of tumor growth, prevention of abscopal tumors, and excellent inhibition of lung metastasis.

Engineering Thermo-pH Dual Responsive Hydrogel for Enhanced Tumor Accumulation, Penetration, and Chemo-Protein Combination Therapy

Purpose

Combined chemotherapeutic drug and protein drug has been a widely employed strategy for tumor treatment. To realize both tumor accumulation and deep tumor penetration for drugs with different pharmacokinetics, we propose a structure-transformable, thermo-pH dual responsive co-delivery system to co-load granzyme B/docetaxel (GrB/DTX).

Methods

Thermo-sensitive hydrogels based on diblock copolymers (mPEG-b-PELG) were synthesized through ring opening polymerization. GrB/DTX mini micelles (GDM) was developed by co-loading these two drugs in pH-sensitive mini micelles, and the GDM-incorporated thermo-sensitive hydrogel (GDMH) was constructed. The thermo-induced gelation behavior of diblock copolymers and the physiochemical properties of GDMH were characterized. GDMH degradation and deep tumor penetration of released mini micelles were confirmed. The pH-sensitive disassembly and lysosomal escape abilities of released mini micelles were evaluated. In vitro cytotoxicity was studied using MTT assays and the in vivo antitumor efficacy study was evaluated in B16-bearing C57BL/6 mice.

Results

GDMH was gelatinized at body temperature and can be degraded by proteinase to release mini micelles. The mini micelles incorporated in GDMH can achieve deep tumor penetration and escape from lysosomes to release GrB and DTX. MTT results showed that maximum synergistic antitumor efficacy of GrB and DTX was observed at mass ratio of 1:100. Our in vivo antitumor efficacy study showed that GDMH inhibited tumor growth in the subcutaneous tumor model and in the post-surgical recurrence model.

Conclusion

The smart-designed transformable GDMH can facilitate tumor accumulation, deep tumor penetration, and rapid drug release to achieve synergistic chemo-protein therapy.

Rational design and latest advances of codelivery systems for cancer therapy

Current treatments have limited effectiveness in treating tumors. The combination of multiple drugs or treatment strategies is widely studied to improve therapeutic effect and reduce adverse effects of cancer therapy. The codelivery system is the key to realize combined therapies. It is necessary to design and construct different codelivery systems in accordance with the variable structures and properties of cargoes and vectors. This review presented the typical design considerations about codelivery vectors for cancer therapy and described the current state of codelivery systems from two aspects: different types of vectors and collaborative treatment strategies. The commonly used loading methods of cargoes into the vectors, including physical and chemical processes, are discussed in detail. Finally, we outline the challenges and perspectives about the improvement of codelivery systems.

Towards a more precise therapy in cancer: Exploring epigenetic complexity

A plethora of preclinical evidences suggests that pharmacological targeting of epigenetic dysregulation is a potent strategy to combat human diseases. Nevertheless, the implementation of epidrugs in clinical practice is very scarce and mainly limited to haematological malignancies. In this review, we discuss cutting-edge strategies to foster the chemical design, the biological rationale and the clinical trial development of epidrugs. Specifically, we focus on the development of dual hybrids to exploit multitargeting of key epigenetic molecules deregulated in cancer; the study of epigenetic-synthetic lethality interactions as a mechanism to address loss-of-function mutations, and the combination of epidrugs with other therapies such as immunotherapy to avoid acquired chemoresistance and increase therapy sensitivity. By exploring these challenges, among others, the field of epigenetic chemical biology will increase its potential for clinical benefit, and more effective strategies targeting the aberrant epigenome in cancer are likely to be developed both in haematological and solid tumours.

Injectable DNA-architected nanoraspberry depot-mediated on-demand programmable refilling and release drug delivery

Drug delivery depots boosting a local concentration of therapeutic agents have received great attention in clinical applications due to their low occurrence of side effects and high therapeutic efficacy. However, once the payload is exhausted, the local drug concentration will be lower than the therapeutic window. To address this issue, an injectable double-strand deoxyribonucleic acid (DNA)-architected nanoraspberry depot (DNR-depot) was developed that can refill doxorubicin (Dox, an anticancer drug) from the blood and remotely control drug release on demand. The large porous surface on a uniform nanoraspberry (NR) filled covalently with DNA serves as a Dox sponge-like refilling reservoir, and the NR serves as a magnetic electrical absorber. Via the strong affinity between Dox and DNA molecules, the refilling process of Dox can be achieved on DNR-depot both in vitro and in vivo. Upon high-frequency magnetic field (HFMF) treatment, the remotely triggered release of Dox is actuated by the dissociation of Dox and DNA molecules, facilitating an approximately 800% improvement in drug concentration at the tumor site compared to free Dox injection alone. Furthermore, the cycles of refilling and release can be carried out more than 3 times in vivo within 21 days. The combination of refilling and HFMF-programmable Dox release in tumors via DNR-depot can effectively inhibit tumor growth for 30 days.

Engineering nanoparticles to reprogram radiotherapy and immunotherapy: recent advances and future challenges

Nanoparticles (NPs) have been increasingly studied for radiosensitization. The principle of NPs radio-enhancement is to use high-atomic number NPs (e.g. gold, hafnium, bismuth and gadolinium) or deliver radiosensitizing substances, such as cisplatin and selenium. Nowadays, cancer immunotherapy is emerged as a promising treatment and immune checkpoint regulation has a potential property to improve clinical outcomes in cancer immunotherapy. Furthermore, NPs have been served as an ideal platform for immunomodulator system delivery. Owing to enhanced permeability and retention (EPR) effect, modified-NPs increase the targeting and retention of antibodies in target cells. The purpose of this review is to highlight the latest progress of nanotechnology in radiotherapy (RT) and immunotherapy, as well as combining these three strategies in cancer treatment. Overall, nanomedicine as an effective strategy for RT can significantly enhance the outcome of immunotherapy response and might be beneficial for clinical transformation.

Stimuli-Responsive Delivery of Growth Factors for Tissue Engineering

Growth factors (GFs) play a crucial role in directing stem cell behavior and transmitting information between different cell populations for tissue regeneration. However, their utility as therapeutics is limited by their short half-life within the physiological microenvironment and significant side effects caused by off-target effects or improper dosage. "Smart" materials that can not only sustain therapeutic delivery over a treatment period but also facilitate on-demand release upon activation are attracting significant interest in the field of GF delivery for tissue engineering. Three properties are essential in engineering these "smart" materials: 1) the cargo vehicle protects the encapsulated therapeutic; 2) release is targeted to the site of injury; 3) cargo release can be modulated by disease-specific stimuli. The aim of this review is to summarize the current research on stimuli-responsive materials as intelligent vehicles for controlled GF delivery; Five main subfields of tissue engineering are discussed: skin, bone and cartilage, muscle, blood vessel, and nerve. Challenges in achieving such "smart" materials and perspectives on future applications of stimuli-responsive GF delivery for tissue regeneration are also discussed.

Structurally Tunable pH-responsive Phosphine Oxide Based Gels by Facile Synthesis Strategy

Design and synthesis of nanostructured responsive gels have attracted increasing attention, particularly in the biomedical domain. Polymer chain configurations and nanodomain sizes within the network can be used to steer their functions as drug carriers. Here, a catalyst-free facile one-step synthesis strategy is reported for the design of pH-responsive gels and controlled structures in nanoscale. Transparent and impurity free gels were directly synthesized from trivinylphosphine oxide (TVPO) and cyclic secondary diamine monomers via Michael addition polymerization under mild conditions. NMR analysis confirmed the consumption of all TVPO and the absence of side products, thereby eliminating post purification steps. The small-angle X-ray scattering (SAXS) elucidates the nanoscale structural features in gels, that is, it demonstrates the presence of collapsed nanodomains within gel networks and it was possible to tune the size of these domains by varying the amine monomers and the nature of the solvent. The fabricated gels demonstrate structure tunability via solvent-polymer interactions and pH specific drug release behavior. Three different anionic dyes (acid blue 80, acid blue 90, and fluorescein) of varying size and chemistry were incorporated into the hydrogel as model drugs and their release behavior was studied. Compared to acidic pH, a higher and faster release of acid blue 80 and fluorescein was observed at pH 10, possibly because of their increased solubility in alkaline pH. In addition, their release in phosphate buffered saline (PBS) and simulated body fluid (SBF) matrix was positively influenced by the ionic interaction with positively charged metal ions. In the case of hydrogel containing acid blue 90 a very low drug release (<1%) was observed, which is due to the reaction of its accessible free amino group with the vinyl groups of the TVPO. In vitro evaluation of the prepared hydrogel using human dermal fibroblasts indicates no cytotoxic effects, warranting further research for biomedical applications. Our strategy of such gel synthesis lays the basis for the design of other gel-based functional materials.

Modulation of tumor microenvironment for immunotherapy: focus on nanomaterial-based strategies

Recent advances in the field of immunotherapy have profoundly opened up the potential for improved cancer therapy and reduced side effects. However, the tumor microenvironment (TME) is highly immunosuppressive, therefore, clinical outcomes of currently available cancer immunotherapy are still poor. Recently, nanomaterial-based strategies have been developed to modulate the TME for robust immunotherapeutic responses. In this review, the immunoregulatory cell types (cells relating to the regulation of immune responses) inside the TME in terms of stimulatory and suppressive roles are described, and the technologies used to identify and quantify these cells are provided. In addition, recent examples of nanomaterial-based cancer immunotherapy are discussed, with particular emphasis on those designed to overcome barriers caused by the complexity and diversity of TME.

Coordinating bioorthogonal reactions with two tumor-microenvironment-responsive nanovehicles for spatiotemporally controlled prodrug activation

Precise activation of prodrugs in tumor tissues is critical to ensuring specific antitumor efficacy, meanwhile reducing the serious adverse effects. Here, a spatiotemporally controlled prodrug activation strategy was provided by integrating the inverse electron demand Diels-Alder (IEDDA) reaction with two tumor-microenvironment-responsive nanovehicles. The prodrug (Dox-TCO) and [4-(6-methyl-1,2,4,5-tetrazin-3-yl)phenyl]methanamine (Tz) were separately camouflaged into low pH and matrix metalloproteinase 2 (MMP-2) sensitive micellar nanoparticles. After systemic administration, only in the tumor tissues could both the nanovehicles dissociate via responding to two special tumor microenvironments, with Dox-TCO and Tz released and then immediately triggering the prodrug activation through the IEDDA reaction. The hierarchically regulated and locally confined Dox liberation led to dramatically decreased side-effects that were much lower than those of the clinical Doxorubicin Hydrochloride Liposomal Injection (Doxil), while the antitumor therapeutic effect was potent.

Tumor immune microenvironment modulation-based drug delivery strategies for cancer immunotherapy

The past years have witnessed promising clinical feedback for anti-cancer immunotherapies, which have become one of the hot research topics; however, they are limited by poor delivery kinetics, narrow patient response profiles, and systemic side effects. To the best of our knowledge, the development of cancer is highly associated with the immune system, especially the tumor immune microenvironment (TIME). Based on the comprehensive understanding of the complexity and diversity of TIME, drug delivery strategies focused on the modulation of TIME can be of great significance for directing and improving cancer immunotherapy. This review highlights the TIME modulation in cancer immunotherapy and summarizes the versatile TIME modulation-based cancer immunotherapeutic strategies, medicative principles and accessory biotechniques for further clinical transformation. Remarkably, the recent advances of cancer immunotherapeutic drug delivery systems and future prospects of TIME modulation-based drug delivery systems for much more controlled and precise cancer immunotherapy will be emphatically discussed.

Smart Injectable Hydrogels for Cancer Immunotherapy

Hydrogels, a class of materials with a 3D network structure, are widely used in various fields especially in biomedicine. Injectable hydrogels could facilitate the encapsulation and controlled release of small molecular drugs, macromolecular therapeutics, and even cells. With the rapid development of cancer immunotherapy, such injectable hydrogels have attracted wide attention for local immunomodulation to boost systemic anticancer immune responses, realizing more effective immunotherapy at lower doses. The latest progresses in the development of various smart injectable hydrogels for cancer immunotherapy are summarized here. Although applied locally, such injectable hydrogels can activate systemic antitumor immune responses, safely and effectively inhibiting the tumor metastasis and recurrence. Moreover, it is discussed how injectable hydrogel‐based cancer immunotherapy would contribute to the development of next generation of cancer treatment together with their potential for clinical translation.

Clinical Epigenetics of Neuroendocrine Tumors: The Road Ahead

Neuroendocrine tumors, or NETs, are cancer originating in neuroendocrine cells. They are mostly found in the gastrointestinal tract or lungs. Functional NETs are characterized by signs and symptoms caused by the oversecretion of hormones and other substances, but most NETs are non-functioning and diagnosis in advanced stages is common. Thus, novel diagnostic and therapeutic strategies are warranted. Epigenetics may contribute to refining the diagnosis, as well as to identify targeted therapy interfering with epigenetic-sensitive pathways. The goal of this review was to discuss the recent advancement in the epigenetic characterization of NETs highlighting their role in clinical findings.

Nanodiamond-Mediated Delivery of a G9a Inhibitor for Hepatocellular Carcinoma Therapy

Hepatocellular carcinoma (HCC) is the most common primary liver cancer with high mortality but limited therapeutic options. Epigenetic regulations including DNA methylation and histone modification control gene expressions and play a crucial role during tumorigenesis. G9a, also known as EHMT2 (euchromatic histone-lysine N-methyltransferase 2), is a histone methyltransferase predominantly responsible for dimethylation of histone H3 lysine 9 (H3K9). G9a has been shown to play a key role in promoting tumor progression. Recent studies have identified that G9a is a critical mediator of HCC pathogenesis. UNC0646 is a G9a inhibitor that has shown potent in vitro efficacy. However, due to its water insolubility, the in vivo efficacy of UNC0646 is not satisfactory. In this study, nanodiamonds (NDs) were utilized as a drug delivery platform to improve in vivo delivery of this small-molecule inhibitor. Our results showed that ND-UNC0646 complexes could be rapidly synthesized by physical adsorption, meanwhile possessing favorable drug delivery properties and was able to improve the dispersibility of UNC0646 in water, therefore making it amenable for intravenous administration. The release profile of UNC0646 from ND-UNC0646 was demonstrated to be pH-responsive. Moreover, ND-UNC0646 maintained the biological functionality of UNC0646, with higher efficacy in reducing H3K9 methylation as well as enhanced invasion suppressive effects. Most importantly, increased in vivo efficacy was demonstrated using an orthotopic HCC mouse model, which paves the way of translating this small-molecule inhibitor toward HCC treatment. Our work demonstrates the potential of NDs in the clinical application for HCC treatment.

Ultrathin metal-organic layer-mediated radiotherapy-radiodynamic therapy enhances immunotherapy of metastatic cancers

Checkpoint blockade immunotherapy (CBI) is effective in promoting a systemic immune response against some metastatic tumors. The reliance on the pre-existing immune environment of the tumor, however, limits the efficacy of CBI on a broad spectrum of cancers. Herein, we report the design of a novel nanoscale metal-organic layer (nMOL), Hf-MOL, for effective treatment of local tumors by enabling radiotherapy-radiodynamic therapy (RT-RDT) with low-dose X-rays and, when in combination with an immune checkpoint inhibitor, regression of metastatic tumors by re-activating anti-tumor immunity and inhibiting myeloid-derived suppressor cells. Owing to the reduced dimensionality, nMOLs allow facile diffusion of reactive oxygen species and exhibit superior RT-RDT effects. The synergy of Hf-MOL-enabled RT-RDT immune activation and anti-programmed death ligand 1 (anti-PD-L1) CBI led to robust abscopal effects on a series of bilateral models of colon, head and neck, and breast cancers and significant anti-metastatic effects on an orthotopic model of breast cancer.

Development of cancer immunotherapy based on PD-1/PD-L1 pathway blockade

Programmed death receptor 1 (PD-1)/programmed death ligand 1 (PD-L1) blockade therapy has achieved considerable success in various tumours. However, only a fraction of patients benefit from its clinical application, and some patients might be suffer from tumour resistance against PD-1/PD-L1 blockade therapy after the original response. In this review, we summarized the main reasons that caused the low response rate of PD-/PD-L1 blockade therapy: firstly, the off-target of PD-1/PD-L1 blocking agents, which is also the main factor of the side effect of autoimmune disorders; secondly, the insufficient infiltration of T cells in a tumour microenvironment; thirdly, the low immunogenicity of tumor cells; fourth, other immunosuppressive components impairing the therapeutic efficacy of the immunotherapy based on the PD-/PD-L1 blockade, and introducing some updated the delivery system of PD-1/PD-L1 blocking agents and the combination therapy based on PD-1/PD-L1 inhibitors and other therapeutics that can complement and promote each other to achieve improved immune response.

Engineering Nanoparticles to Reprogram the Tumor Immune Microenvironment for Improved Cancer Immunotherapy

Immunotherapy is rapidly maturing towards extensive clinical use. However, it does not work well in large patient populations because of an immunosuppressed microenvironment and limited reinvigoration of antitumor immunity. The tumor microenvironment is a complex milieu in which the principles of physiology and anatomy are defied and which is considered an immune-privileged site promoting T cell exhaustion. Tremendous research interest exists in developing nanoparticle-based approaches to modulate antitumor immune responses. The increasing use of immunotherapies in the clinic requires robust programming of immune cells to boost antitumor immunity. This review summarizes recent advances in the engineering of nanoparticles for improved anticancer immunotherapy. It discusses emerging nanoparticle-based approaches for the modulation of tumor cells and immune cells, such as dendritic cells, T cells and tumor-associated macrophages, with the intention to overcome challenges currently faced in the clinic. Furthermore, this review describes potentially curative combination therapeutic approaches to provoke effective tumor antigen-specific immune responses. We foresee a future in which improvement in patient's surveillance will become a mainstream practice.

In situ biosynthesized gold nanoclusters inhibiting cancer development via the PI3K-AKT signaling pathway

Nanomaterials have made great breakthroughs in drug delivery. However, in previous studies, nanomaterials have been mostly used as vehicles to transport drugs into tumors. Herein, we first found that the in situ biosynthesized gold nanoparticles (Au NCs) can inhibit cancer development via the inhibition of some signaling pathways. Classical cell phenotypic assay tests and orthotropic liver tumor model both showed that the in situ biosynthesized Au NCs could inhibit tumor development. With the help of the RNA-seq analysis, we found that the in situ biosynthesized Au NCs could significantly inhibit the PI3K-AKT signaling pathway, thus effectively impeding tumor development. This facile and effective tumor targeting theranostics in vivo can effectively cure cancers in future clinical applications.

Chondroitin Sulfate-Linked Prodrug Nanoparticles Target the Golgi Apparatus for Cancer Metastasis Treatment

Metastasis is a multistep biological process regulated by multiple signaling pathways. The integrity of the Golgi apparatus plays an important role in these signaling pathways. Inspired by the mechanism and our previous finding about accumulation of chondroitin sulfate in Golgi apparatus in hepatic stellate cells, we developed a Golgi apparatus-targeting prodrug nanoparticle system by synthesizing retinoic acid (RA)-conjugated chondroitin sulfate (CS) (CS-RA). The prodrug nanoparticles appeared to accumulate in the Golgi apparatus in cancer cells and realized RA release under an acidic environment. We confirmed that CS-RA exhibited successful inhibition of multiple metastasis-associated proteins expression in vitro and in vivo by disruption of the Golgi apparatus structure. Following loading with paclitaxel (PTX), the CS-RA based nanoformulation (PTX-CS-RA) inhibited migration, invasion, and angiogenesis in vitro and suppressed tumor growth and metastasis in 4T1-Luc bearing mice. This multistep targeted nanoparticle system potentially enhanced the effect of antimetastasis combined with chemotherapy.

Robust magnetic double-network hydrogels with self-healing, MR imaging, cytocompatibility and 3D printability

Herein, we have fabricated a novel robust self-healing magnetic double-network hydrogel by multiple interactions between bondable magnetic Fe3O4 and chitosan-polyolefin matrix, and the hydrogel also exhibits an excellent magnetogenic effect and MR imageability. The practical potential of the magnetic double-network hydrogel is further revealed by its 3D-printing performance.