Injectable polypeptide hydrogel-based co-delivery of vaccine and immune checkpoint inhibitors improves tumor immunotherapy

A dendritic cell-recruiting, antimicrobial blood clot hydrogel for melanoma recurrence prevention and infected wound management

Surgical resection, the mainstay for melanoma treatment, faces challenges due to high tumor recurrence rates and complex postoperative wound healing. Chronic inflammation from residual disease and the risk of secondary infections impede healing. We introduce an innovative, injectable hydrogel system that integrates a multifaceted therapeutic approach. The hydrogel, crosslinked by calcium ions with sodium alginate, encapsulates a blood clot rich in dendritic cells (DCs) chemoattractants and melanoma cell-derived nanovesicles (NVs), functioning as a potent immunostimulant. This in situ recruitment strategy overcomes the limitations of subcutaneous tumor vaccine injections and more effectively achieves antitumor immunity. Additionally, the hydrogel incorporates Chlorella extracts, enhancing its antimicrobial properties to prevent wound infections and promote healing. One of the key findings of our research is the dual functionality of Chlorella extracts; they not only expedite the healing process of infected wounds but also increase the hydrogel's ability to stimulate an antitumor immune response. Given the patient-specific nature of the blood clot and NVs, our hydrogel system offers customizable solutions for individual postoperative requirements. This personalized approach is highlighted by our study, which demonstrates the synergistic impact of the composite hydrogel on preventing melanoma recurrence and hastening wound healing, potentially transforming postsurgical melanoma management.

A Near-Infrared II Photo-Triggered Multifunctional Plasmonic Hyperthermia Immunomodulator for SERS-Guided Combination Cancer Immunotherapy

Immunotherapy represents a promising therapeutic strategy for cancer treatment, but its clinical applications are currently hindered by insufficient therapeutic potency, nonspecific delivery, and adverse side effects. Herein, a novel near-infrared II (NIR-II) photo-triggered plasmonic hyperthermia immunomodulator (RP@IR-pcNS@HA nanoparticles (NPs)) for anticancer treatment of both primary and distant cancers is reported. This immunomodulator comprises an IR-1061 dye-encoded NIR-II porous cubic AuAg nanoshell (pcNS) loaded with a Toll-like receptor 7 agonist - R837 in phase change materials (PCMs), further modified with hyaluronic acid (HA). In response to NIR-II photoirradiation, the RP@IR-pcNS@HA NPs controllably deliver and release R837 to tumor sites, subsequently perform plasmonic hyperthermia therapy for direct ablation of primary tumors, and elicit robust anticancer immune responses. It is demonstrated that upon NIR-II irradiation, such a plasmonic hyperthermia immunomodulator combined with anti-programmed death 1 antibody (αPD-1) completely eradicates both primary and distant cancers. In addition, this combination treatment successfully elicits robust immune memory responses for effective suppression of recurrence and distant metastasis of cancer. With the excellent NIR-II surface-enhanced Raman scattering (SERS) detection ability, the RP@IR-pcNS@HA NPs combined with αPD-1 represent an efficient way to develop high-performance theranostic agents for SERS-guided combination cancer photoimmunotherapy.

Injectable Polydopamine Nanoparticle-Incorporated Hydrogels for Antiangiogenesis and Stimulating Tumoricidal Immunity to Inhibit Metastasis and Recurrence Postresection

Surgical resection is still the main means for clinical treatments of breast cancer, but the postoperative immunosuppressive microenvironment and neoangiogenesis of the residual tumors easily lead to tumor metastasis and recurrence, which will further endanger patients' lives. The combination of antiangiogenic therapy and immunotherapy may promote the mutually reinforced cycle of immune reprogramming and vascular normalization to avoid tumor metastasis and recurrence. Herein, we prepared polydopamine nanoparticles for improving tissue adhesion and enriching tumor-associated antigens. This nanoregulator together with regorafenib (REG) was further incorporated into a hydrogel developed from grafting adipic acid dihydrazide onto 2,2,6,6-tetramethylpiperidine-1-oxyl radical oxidized chitin and oxidized hyaluronic acid, which was injectable at the cavity after subcutaneous tumor surgery with good mechanical properties and degradability. The system showed long-term release of REG. After combining with anti-PD-L1, the hydrogel applied to the surgical wound exhibited a reduction in tumor metastasis and recurrence. This effect was achieved by suppressing angiogenesis and enhancing antitumor immunity, characterized by increased levels of effector T lymphocytes and activation of dendritic cells within tumors, spleens, and draining lymph nodes. The injectable hydrogel offers a promising strategy for postoperative management aimed at preventing tumor metastasis and recurrence.

Rapid Hemostasis Tumor In Situ Hydrogel Vaccines for Colorectal Cancer Chemo-Immunotherapy

Due to the high heterogeneity and the immunosuppressive microenvironment of tumors, most single antigen tumor vaccines often fail to elicit potent antitumor immune responses in clinical trials, resulting in unsatisfactory therapy effects. Hence, personalized tumor vaccines have become a promising modality for cancer immunotherapy. Here, we have developed a tumor in situ hydrogel vaccine (AH/DA-OR) capable of rapid hemostasis for personalized tumor immunotherapy, composed of dopamine-grafted hyaluronic acid (HA/DA) combined with sodium alginate (ALG), with coloaded oxaliplatin (OXA) and resiquimod (R848). The ALG and HA framework imparts excellent biocompatibility to the hydrogel, and dopamine (DA) modification endows it with rapid hemostatic functionality. Following local peritumor injection of AH/DA-OR into the tumor, the in situ hydrogel vaccine achieved the sustained release of the chemotherapeutic agent, OXA, inducing immunogenic cell death in tumor cells and effectively releasing personalized tumor-associated antigens to activate immune responses. Simultaneously, local R848 adjuvant sustained release at the tumor site enhanced immune responses, minimized drug side effects, and amplified immunotherapy effects. Finally, the hydrogel vaccine effectively activated host immune responses to suppress CT26 colorectal cancer growth in vivo, also exhibiting superior inhibition of untreated tumor growth at distant sites. This strategy of rapid hemostasis of tumor in situ hydrogel vaccine holds significant clinical potential and provides a paradigm for achieving secure and robust immunotherapy.

Emerging Strategies for Local Delivery of Immune Checkpoint Inhibitors to Potentiate Cancer Immunotherapy: Current Status and Future Prospects

Cancer constitutes a significant threat to patients' lives worldwide. Immunotherapy, particularly immune checkpoint inhibitors (ICIs) that boost antitumor immunity by targeting immune checkpoint components, has emerged as a promising strategy for its treatment in recent years. However, the objective response rates of the ICIs are unsatisfactory. As the primary route, systemic administration of ICIs is often accompanied by immune-related adverse events. Local delivery of ICIs serves as a potential therapeutic strategy that can improve the efficacy while simultaneously reducing side effects through precise drug release at the tumor site. Initial validation of direct local application of ICIs for tumors in clinical trials has indicated reduced side effects and improved efficacy, while low bioavailability remains a challenge. Furthermore, research on various carriers, including nanoparticles, microneedles, hydrogels, combined platforms, and implantable devices for local release of ICIs has exhibited applying potential in treating murine tumors, among which combined platforms such as combined hydrogel system hold the highest promise due to their encompassment of the advantages of multiple carriers. These carriers, by incorporating ICIs and other therapeutics, could manage cancers more potently, which needs to be confirmed in clinical trials after the refinement of their biocompatibility. This review summarizes the latest research advancements regarding local administration of ICIs, with a particular focus on the carriers for local delivery as well as the combination therapies, thus providing novel insights and research guidance for scholars to enhance the efficacy of locally delivered ICIs on managing multiple cancers in the future.

Hydrogel-based platforms for site-specific doxorubicin release in cancer therapy

Hydrogels are promising candidates for the delivery of therapeutics in the treatment of human cancers. Regarding to the biocomaptiiblity, high drug and encapsulation efficacy and adjustable physico-chemical features, the hydrogels have been widely utilized for the delivery of chemotherapy drugs. Doxorubicin (DOX) is one of the most common chemotherapy drugs used in cancer therapy through impairing topoisomerase II function and increasing oxidative damage. However, the tumor cells have developed resistance into DOX-mediated cytotoxic impacts, requiring the delivery systems to increase internalization and anti-cancer activity of this drug. The hydrogels can deliver DOX in a sustained manner to maximize its anti-cancer activity, improving cancer elimination and reduction in side effects and drug resistance. The natural-based hydrogels such as chitosan, alginate and gelatin hydrogels have shown favourable biocompatibility and degradability in DOX delivery for tumor suppression. The hydrogels are able to co-deliver DOX with other drugs or genes to enhance drug sensitivity and mediate polychemotherapy, synergistically suppressing cancer progression. The incorporation of nanoparticles in the structure of hydrogels can improve the sustained release of DOX and enhancing intracellular internalization, accelerating DOX's cytotoxicity. Furthermore, the stimuli-responsive hydrogels including pH-, redox- and thermo-sensitive platforms are able to improve the specific release of DOX at the tumor site. The DOX-loaded hydrogels can be further employed in the clinic for the treatment of cancer patients and improving efficacy of chemotherapy.

Diverse Strategies to Develop Poly(ethylene glycol)-Polyester Thermogels for Modulating the Release of Antibodies

In this work, we present basic research on developing thermogel carriers containing high amounts of model antibody immunoglobulin G (IgG) with potential use as injectable molecules. The quantities of IgG loaded into the gel were varied to evaluate the possibility of tuning the dose release. The gel materials were based on blends of thermoresponsive and degradable ABA-type block copolymers composed of poly(lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(lactide-co-glycolide) (PLGA-PEG-PLGA) or poly(lactide-co-caprolactone)-b-poly(ethylene glycol)-b-(lactide-co-caprolactone) (PLCL-PEG-PLCL). Primarily, the gels with various amounts of IgG were obtained via thermogelation, where the only factor inducing gel formation was the change in temperature. Next, to control the gels' mechanical properties, degradation rate, and the extent of antibody release, we have tested two approaches. The first one involved the synergistic physical and chemical crosslinking of the copolymers. To achieve this, the hydroxyl groups located at the ends of the PLGA-PEG-PLGA chain were modified into acrylate groups. In this case, the thermogelation was accompanied by chemical crosslinking through the Michael addition reaction. Such an approach increased the dynamic mechanical properties of the gels and simultaneously prolonged their decomposition time. An alternative solution was to suspend crosslinked PEG-polyester nanoparticles loaded with IgG in a PLGA-PEG-PLGA gelling copolymer. We observed that loading IgG into thermogels lowered the gelation temperature (TGEL) value and increased the storage modulus of the gels, as compared with gels without IgG. The prepared gel materials were able to release the IgG from 8 up to 80 days, depending on the gel formulation and on the amount of loaded IgG. The results revealed that additional, chemical crosslinking of the thermogels and also suspension of particles in the polymer matrix substantially extended the duration of IgG release. With proper matching of the gel composition, environmental conditions, and the type and amount of active substances, antibody-containing thermogels can serve as effective IgG delivery materials.

Injectable Hydrogels: A Paradigm Tailored with Design, Characterization, and Multifaceted Approaches

Biomaterials denoting self-healing and versatile structural integrity are highly curious in the biomedicine segment. The injectable and/or printable 3D printing technology is explored in a few decades back, which can alter their dimensions temporarily under shear stress, showing potential healing/recovery tendency with patient-specific intervention toward the development of personalized medicine. Thus, self-healing injectable hydrogels (IHs) are stunning toward developing a paradigm for tissue regeneration. This review comprises the designing of IHs, rheological characterization and stability, several benchmark consequences for self-healing IHs, their translation into tissue regeneration of specific types, applications of IHs in biomedical such as anticancer and immunomodulation, wound healing and tissue/bone regeneration, antimicrobial potentials, drugs, gene and vaccine delivery, ocular delivery, 3D printing, cosmeceuticals, and photothermal therapy as well as in other allied avenues like agriculture, aerospace, electronic/electrical industries, coating approaches, patents associated with therapeutic/nontherapeutic avenues, and numerous futuristic challenges and solutions.

Advancements in Photothermal Therapy Using Near-Infrared Light for Bone Tumors

Bone tumors, particularly osteosarcoma, are prevalent among children and adolescents. This ailment has emerged as the second most frequent cause of cancer-related mortality in adolescents. Conventional treatment methods comprise extensive surgical resection, radiotherapy, and chemotherapy. Consequently, the management of bone tumors and bone regeneration poses significant clinical challenges. Photothermal tumor therapy has attracted considerable attention owing to its minimal invasiveness and high selectivity. However, key challenges have limited its widespread clinical use. Enhancing the tumor specificity of photosensitizers through targeting or localized activation holds potential for better outcomes with fewer adverse effects. Combinations with chemotherapies or immunotherapies also present avenues for improvement. In this review, we provide an overview of the most recent strategies aimed at overcoming the limitations of photothermal therapy (PTT), along with current research directions in the context of bone tumors, including (1) target strategies, (2) photothermal therapy combined with multiple therapies (immunotherapies, chemotherapies, and chemodynamic therapies, magnetic, and photodynamic therapies), and (3) bifunctional scaffolds for photothermal therapy and bone regeneration. We delve into the pros and cons of these combination methods and explore current research focal points. Lastly, we address the challenges and prospects of photothermal combination therapy.

Nanofibrous MultiDomain Peptide Hydrogels Provide T Cells a 3D, Cytocompatible Environment for Cell Expansion and Antigen-Specific Killing

T cells have the ability to recognize and kill specific target cells, giving therapies based on their potential for treating infection, diabetes, cancer, and other diseases. However, the advancement of T cell-based treatments has been hindered by difficulties in their ex vivo activation and expansion, the number of cells required for sustained in vivo levels, and preferential localization following systemic delivery. Biomaterials may help to overcome many of these challenges by providing a combined means of proliferation, antigen presentation, and cell localization upon delivery. In this work, we studied self-assembling Multidomain Peptides (MDPs) as scaffolds for T cell culture, activation, and expansion. We evaluated the effect of different MDP chemistries on their biocompatibility with T cells and the maintenance of antigen specificity for T cells cultured in the hydrogels. We also examined the potential application of MDPs as scaffolds for T cell activation and expansion and the effect of MDP encapsulation on T cell phenotype. We found high cell viability when T cells were encapsulated in noncationic MDPs, O5 and D2, and superior retention of antigen specificity and tumor-reactivity were preserved in the anionic MDP, D2. Maintenance of antigen recognition by T cells in D2 hydrogels was confirmed by quantifying immune synapses of T Cells engaged with antigen-presenting cancer cells. When 3D cultured in anionic MDP D2 coloaded with anti-CD3, anti-CD28, IL2, IL7, and IL15, we observed successful T cell proliferation evidenced by upregulation of CD27 and CD107a. This study is the first to investigate the potential of self-assembling peptide-based hydrogels as 3D scaffolds for human T cell applications and demonstrates that MDP hydrogels are a viable platform for enabling T cell in vitro activation, expansion, and maintenance of antigen specificity and therefore a promising tool for future T cell-based therapies.

Sustained release of a human PD-L1 single-domain antibody using peptide-based hydrogels

Monoclonal antibodies (mAbs) targeting the immune checkpoint axis, which contains the programmed cell death protein-1 (PD-1) and its ligand PD-L1, revolutionized the field of oncology. Unfortunately, the large size of mAbs and the presence of an Fc fraction limit their tumor penetrative capacities and support off-target effects, potentially resulting in unresponsive patients and immune-related adverse events (irAEs) respectively. Single-domain antibodies (sdAbs) are ten times smaller than conventional mAbs and represent an emerging antibody subclass that has been proposed as next generation immune checkpoint inhibitor (ICI) therapeutics. They demonstrate favorable characteristics, such as an excellent stability, high antigen-binding affinity and an enhanced tumor penetration. Because sdAbs have a short half-life, methods to prolong their presence in the circulation and at the target site might be necessary in some cases to unfold their full therapeutic potential. In this study, we investigated a peptide-based hydrogel as an injectable biomaterial depot formulation for the sustained release of the human PD-L1 sdAb K2. We showed that a hydrogel composed of the amphipathic hexapeptide hydrogelator H-FQFQFK-NH2 prolonged the in vivo release of K2 after subcutaneous (s.c.) injection, up to at least 72 h, as monitored by SPECT/CT and fluorescence imaging. Additionally, after encapsulation in the hydrogel and s.c. administration, a significantly extended systemic presence and tumor uptake of K2 was observed in mice bearing a melanoma tumor expressing human PD-L1. Altogether, this study describes how peptide hydrogels can be exploited to provide the sustained release of sdAbs, thereby potentially enhancing its clinical and therapeutic effects.

Research progress on hydrogel-based drug therapy in melanoma immunotherapy

Melanoma is one of the most aggressive skin tumors, and conventional treatment modalities are not effective in treating advanced melanoma. Although immunotherapy is an effective treatment for melanoma, it has disadvantages, such as a poor response rate and serious systemic immune-related toxic side effects. The main solution to this problem is the use of biological materials such as hydrogels to reduce these side effects and amplify the immune killing effect against tumor cells. Hydrogels have great advantages as local slow-release drug carriers, including the ability to deliver antitumor drugs directly to the tumor site, enhance the local drug concentration in tumor tissue, reduce systemic drug distribution and exhibit good degradability. Despite these advantages, there has been limited research on the application of hydrogels in melanoma treatment. Therefore, this article provides a comprehensive review of the potential application of hydrogels in melanoma immunotherapy. Hydrogels can serve as carriers for sustained drug delivery, enabling the targeted and localized delivery of drugs with minimal systemic side effects. This approach has the potential to improve the efficacy of immunotherapy for melanoma. Thus, the use of hydrogels as drug delivery vehicles for melanoma immunotherapy has great potential and warrants further exploration. [BMB Reports 2024; 57(2): 71-78].

In Situ Vaccination with An Injectable Nucleic Acid Hydrogel for Synergistic Cancer Immunotherapy

Recently, therapeutic cancer vaccines have emerged as promising candidates for cancer immunotherapy. Nevertheless, their efficacies are frequently impeded by challenges including inadequate antigen encapsulation, insufficient immune activation, and immunosuppressive tumor microenvironment. Herein, we report a three-in-one hydrogel assembled by nucleic acids (NAs) that can serve as a vaccine to in situ trigger strong immune response against cancer. Through site-specifically grafting the chemodrug, 7-ethyl-10-hydroxycamptothecin (also known as SN38), onto three component phosphorothioate (PS) DNA strands, a Y-shaped motif (Y-motif) with sticky ends is self-assembled, at one terminus of which an unmethylated cytosine-phosphate-guanine (CpG) segment is introduced as an immune agonist. Thereafter, programmed cell death ligand-1 (PD-L1) siRNA that performs as immune checkpoint inhibitor is designed as a crosslinker to assemble with the CpG- and SN38-containing Y-motif, resulting in the formation of final NA hydrogel vaccine. With three functional agents inside, the hydrogel can remarkably induce the immunogenic cell death to enhance the antigen presentation, promoting the dendritic cell maturation and effector T lymphocyte infiltration, as well as relieving the immunosuppressive tumor environment. When inoculated twice at tumor sites, the vaccine demonstrates a substantial antitumor effect in melanoma mouse model, proving its potential as a general platform for synergistic cancer immunotherapy.

PEI-Based Nanoparticles for Tumor Immunotherapy via In Situ Antigen-Capture Triggered by Photothermal Therapy

Activating a tumor antigen-specific immune response is key to the success of tumor immunotherapy and the development of personalized antitumor therapy. Nanocarriers can capture, enrich, and protect in situ produced tumor antigens due to immunogenic cell death (ICD), thus enhancing the tumor-specific immune response. Developing multifunctional nanocarriers that combine multiple antigen capturing mechanisms is crucial to the activation of tumor-specific immune responses. In this study, polyethylenimine (PEI) was employed as a main building block to construct a series of multifunctional indocyanine green (ICG)-loaded nanoparticles to capture antigens via multiple mechanisms: electrostatic interactions with PEI, hydrophobic interactions with the thermosensitive segment (POEGMA300), and covalent bonding with the pyridyl disulfide (PDS) groups, respectively. Their capacity of ICD induction, tumor antigen-capture, and antitumor immune responses were evaluated. Both the intrinsic toxicity of PEI and the ICG-mediated photothermal effect were responsible for inducing ICD. The positively charged PEI segment exhibited the best antigen-capturing ability via electrostatic interactions, promoted bone marrow-derived dendritic cell maturation and CD8+ T cell proliferation, and elicited antitumor immune responses in vivo. PDS groups bonded antigens covalently and significantly contributed to the suppression of distant tumor growth. Although the thermosensitive hydrophobic polymer segment did not contribute positively to antigen capture or tumor growth inhibition, NPs containing all of the functional modules prolonged the survival of tumor-bearing mice more than other treatments. This study provides more chemical insights into the design of polymer-based in situ nanovaccines against cancer.

Polypeptide-Based Systems: From Synthesis to Application in Drug Delivery

Synthetic polypeptides are biocompatible and biodegradable macromolecules whose composition and architecture can vary over a wide range. Their unique ability to form secondary structures, as well as different pathways of modification and biofunctionalization due to the diversity of amino acids, provide variation in the physicochemical and biological properties of polypeptide-containing materials. In this review article, we summarize the advances in the synthesis of polypeptides and their copolymers and the application of these systems for drug delivery in the form of (nano)particles or hydrogels. The issues, such as the diversity of polypeptide-containing (nano)particle types, the methods for their preparation and drug loading, as well as the influence of physicochemical characteristics on stability, degradability, cellular uptake, cytotoxicity, hemolysis, and immunogenicity of polypeptide-containing nanoparticles and their drug formulations, are comprehensively discussed. Finally, recent advances in the development of certain drug nanoformulations for peptides, proteins, gene delivery, cancer therapy, and antimicrobial and anti-inflammatory systems are summarized.

Hydrogel drug delivery systems for minimally invasive local immunotherapy of cancer

Although systemic immunotherapy has achieved durable responses and improved survival for certain patients and cancer types, low response rates and immune system-related systemic toxicities limit its overall impact. Intratumoral (intralesional) delivery of immunotherapy is a promising technique to combat mechanisms of tumor immune suppression within the tumor microenvironment and reduce systemic drug exposure and associated side effects. However, intratumoral injections are prone to variable tumor drug distribution and leakage into surrounding tissues, which can compromise efficacy and contribute to toxicity. Controlled release drug delivery systems such as in situ-forming hydrogels are promising vehicles for addressing these challenges by providing improved spatio-temporal control of locally administered immunotherapies with the goal of promoting systemic tumor-specific immune responses and abscopal effects. In this review we will discuss concepts, applications, and challenges in local delivery of immunotherapy using controlled release drug delivery systems with a focus on intratumorally injected hydrogel-based drug carriers.

Cancer Immunotherapy Using Bioengineered Micro/Nano Structured Hydrogels

Hydrogels, a class of materials with a 3D network structure, are widely used in various applications of therapeutic delivery, particularly cancer therapy. Micro and nanogels as miniaturized structures of the bioengineered hydrogels may provide extensive benefits over the common hydrogels in encapsulation and controlled release of small molecular drugs, macromolecular therapeutics, and even cells. Cancer immunotherapy is rapidly developing, and micro/nanostructured hydrogels have gained wide attention regarding their engineered payload release properties that enhance systemic anticancer immunity. Additionally, they are a great candidate due to their local administration properties with a focus on local immune cell manipulation in favor of active and passive immunotherapies. Although applied locally, such micro/nanostructured can also activate systemic antitumor immune responses by releasing nanovaccines safely and effectively inhibiting tumor metastasis and recurrence. However, such hydrogels are mostly used as locally administered carriers to stimulate the immune cells by releasing tumor lysate, drugs, or nanovaccines. In this review, the latest developments in cancer immunotherapy are summarized using micro/nanostructured hydrogels with a particular emphasis on their function depending on the administration route. Moreover, the potential for clinical translation of these hydrogel-based cancer immunotherapies is also discussed.

Peptide Hydrogels as Immunomaterials and Their Use in Cancer Immunotherapy Delivery

Peptide-based hydrogel biomaterials have emerged as an excellent strategy for immune system modulation. Peptide-based hydrogels are supramolecular materials that self-assemble into various nanostructures through various interactive forces (i.e., hydrogen bonding and hydrophobic interactions) and respond to microenvironmental stimuli (i.e., pH, temperature). While they have been reported in numerous biomedical applications, they have recently been deemed promising candidates to improve the efficacy of cancer immunotherapies and treatments. Immunotherapies seek to harness the body's immune system to preemptively protect against and treat various diseases, such as cancer. However, their low efficacy rates result in limited patient responses to treatment. Here, the immunomaterial's potential to improve these efficacy rates by either functioning as immune stimulators through direct immune system interactions and/or delivering a range of immune agents is highlighted. The chemical and physical properties of these peptide-based materials that lead to immuno modulation and how one may design a system to achieve desired immune responses in a controllable manner are discussed. Works in the literature that reports peptide hydrogels as adjuvant systems and for the delivery of immunotherapies are highlighted. Finally, the future trends and possible developments based on peptide hydrogels for cancer immunotherapy applications are discussed.

Gel/hydrogel-based in situ biomaterial platforms for cancer postoperative treatment and recovery

Tumor surgical resection is the major strategy for cancer treatment. Meanwhile, perioperative treatment especially the postoperative adjuvant anticancer strategies play essential roles in satisfying therapeutic results and rapid recovery. Postoperative tumor recurrence, metastasis, bleeding, inter-tissue adhesion, infection, and delayed wound healing are vital risks that could lead to poor prognosis or even treatment failure. Therefore, methods targeting these postoperative complications are in desperate need. In situ biomaterial-based drug delivery platforms are promising candidates for postoperative treatment and recovery, resulting from their excellent properties including good biocompatibility, adaptive shape, limited systemic effect, designable function, and easy drug loading. In this review, we focus on introducing the gel/hydrogel-based in situ biomaterial platforms involving their properties, advantages, and synthesis procedures. Based on the loaded contents in the gel/hydrogel such as anticancer drugs, immunologic agents, cell components, and multifunctional nanoparticles, we further discuss the applications of the in situ platforms for postoperative tumor recurrence and metastasis inhibition. Finally, other functions aiming at fast postoperative recovery were introduced, including hemostasis, antibacterial infection, adhesion prevention, tissue repair, and wound healing. In conclusion, gel/hydrogel is a developing and promising platform for postoperative treatment, exhibiting gratifying therapeutic effects and inconspicuous toxicity to normal tissues, which deserves further research and exploration.

Local immunotherapy of glioblastoma: A comprehensive review of the concept

Despite advancements in standard treatments, the prognosis of Glioblastoma (GBM) remains poor, prompting research for novel therapies. Immunotherapy is a promising treatment option for GBM, and many immunotherapeutic agents are currently under investigation. Chimeric antigen receptor (CAR) T cells are rapidly evolving in immunotherapy of GBM with many clinical trials showing efficacy of CAR T cells exerting anti-tumor activity following recognition of tumor-associated antigens (TAAs). Exhaustion in CAR T cells can reduce their capacity for long-term persistence and anti-tumor action. Local immunotherapy, which targets the tumor microenvironment and creates a more hospitable immunological environment for CAR T cells, has the potential to reduce CAR T cell exhaustion and increase immunity. Tertiary lymphoid structures (TLS) are ectopic lymphoid-like formations that can develop within the tumor microenvironment or in other non-lymphoid tissues. As a comprehensive local immunotherapy tool, the incorporation of TLS into an implanted biodegradable scaffold has amazing immunotherapeutic potential. The immune response to GBM can be improved even further by strategically inserting a stimulator of interferon genes (STING) agonist into the scaffold. Additionally, the scaffold's addition of glioma stem cells (GSC), which immunotherapeutic approaches may use to target, enhances the removal of cancer cells from their source. Furthermore, it has been demonstrated that GSCs have an impact on TLS formation, which helps to create a favorable tumor microenvironment. Herein, we overview local delivery of a highly specific tandem AND-gate CAR T cell along with above mentioned components. A multifaceted approach that successfully engages the immune system to mount an efficient targeted immune response against GBM is provided by the integration of CAR T cells, TLS, STING agonists, and GSCs within an implantable biodegradable scaffold. This approach offers a promising therapeutic approach for patients with GBM.

Application of Nano-Delivery Systems in Lymph Nodes for Tumor Immunotherapy

Immunotherapy has become a promising research "hotspot" in cancer treatment. "Soldier" immune cells are not uniform throughout the body; they accumulate mostly in the immune organs such as the spleen and lymph nodes (LNs), etc. The unique structure of LNs provides the microenvironment suitable for the survival, activation, and proliferation of multiple types of immune cells. LNs play an important role in both the initiation of adaptive immunity and the generation of durable anti-tumor responses. Antigens taken up by antigen-presenting cells in peripheral tissues need to migrate with lymphatic fluid to LNs to activate the lymphocytes therein. Meanwhile, the accumulation and retaining of many immune functional compounds in LNs enhance their efficacy significantly. Therefore, LNs have become a key target for tumor immunotherapy. Unfortunately, the nonspecific distribution of the immune drugs in vivo greatly limits the activation and proliferation of immune cells, which leads to unsatisfactory anti-tumor effects. The efficient nano-delivery system to LNs is an effective strategy to maximize the efficacy of immune drugs. Nano-delivery systems have shown beneficial in improving biodistribution and enhancing accumulation in lymphoid tissues, exhibiting powerful and promising prospects for achieving effective delivery to LNs. Herein, the physiological structure and the delivery barriers of LNs were summarized and the factors affecting LNs accumulation were discussed thoroughly. Moreover, developments in nano-delivery systems were reviewed and the transformation prospects of LNs targeting nanocarriers were summarized and discussed.

Recent Advances in Molecular Mechanisms of Cancer Immunotherapy

Cancer is among the current leading causes of death worldwide, despite the novel advances that have been made toward its treatment, it is still considered a major public health concern. Considering both the serious impact of cancer on public health and the significant side effects and complications of conventional therapeutic options, the current strategies towards targeted cancer therapy must be enhanced to avoid undesired toxicity. Cancer immunotherapy has become preferable among researchers in recent years compared to conventional therapeutic options, such as chemotherapy, surgery, and radiotherapy. The understanding of how to control immune checkpoints, develop therapeutic cancer vaccines, genetically modify immune cells as well as enhance the activation of antitumor immune response led to the development of novel cancer treatments. In this review, we address recent advances in cancer immunotherapy molecular mechanisms. Different immunotherapeutic approaches are critically discussed, focusing on the challenges, potential risks, and prospects involving their use.

Computational design of a cyclic peptide that inhibits the CTLA4 immune checkpoint

Proteins involved in immune checkpoint pathways, such as CTLA4, PD1, and PD-L1, have become important targets for cancer immunotherapy; however, development of small molecule drugs targeting these pathways has proven difficult due to the nature of their protein-protein interfaces. Here, using a hierarchy of computational techniques, we design a cyclic peptide that binds CTLA4 and follow this with experimental verification of binding and biological activity, using bio-layer interferometry, cell culture, and a mouse tumor model. Beginning from a template excised from the X-ray structure of the CTLA4:B7-2 complex, we generate several peptide sequences using flexible docking and modeling steps. These peptides are cyclized head-to-tail to improve structural and proteolytic stability and screened using molecular dynamics simulation and MM-GBSA calculation. The standard binding free energies for shortlisted peptides are then calculated in explicit-solvent simulation using a rigorous multistep technique. The most promising peptide, cyc(EIDTVLTPTGWVAKRYS), yields the standard free energy -6.6 ± 3.5 kcal mol-1, which corresponds to a dissociation constant of ∼15 μmol L-1. The binding affinity of this peptide for CTLA4 is measured experimentally (31 ± 4 μmol L-1) using bio-layer interferometry. Treatment with this peptide inhibited tumor growth in a co-culture of Lewis lung carcinoma (LLC) cells and antigen primed T cells, as well as in mice with an orthotropic Lewis lung carcinoma allograft model.

Thermo-induced physically crosslinked polypeptide-based block copolymer hydrogels for biomedical applications

Stimuli-responsive synthetic polypeptide-containing block copolymers have received considerable attention in recent years. Especially, unique thermo-induced sol-gel phase transitions were observed for elaborately-designed amphiphilic diblock copolypeptides and a range of poly(ethylene glycol) (PEG)-polypeptide block copolymers. The thermo-induced gelation mechanisms involve the evolution of secondary conformation, enhanced intramolecular interactions, as well as reduced hydration and increased chain entanglement of PEG blocks. The physical parameters, including polymer concentrations, sol-gel transition temperatures and storage moduli, were investigated. The polypeptide hydrogels exhibited good biocompatibility in vitro and in vivo, and displayed biodegradation periods ranging from 1 to 5 weeks. The unique thermo-induced sol-gel phase transitions offer the feasibility of minimal-invasive injection of the precursor aqueous solutions into body, followed by in situ hydrogel formation driven by physiological temperature. These advantages make polypeptide hydrogels interesting candidates for diverse biomedical applications, especially as injectable scaffolds for 3D cell culture and tissue regeneration as well as depots for local drug delivery. This review focuses on recent advances in the design and preparation of injectable, thermo-induced physically crosslinked polypeptide hydrogels. The influence of composition, secondary structure and chirality of polypeptide segments on the physical properties and biodegradation of the hydrogels are emphasized. Moreover, the studies on biomedical applications of the hydrogels are intensively discussed. Finally, the major challenges in the further development of polypeptide hydrogels for practical applications are proposed.

Novel technologies for applying immune checkpoint blockers

Cancer cells develop several ways to subdue the immune system among others via upregulation of inhibitory immune checkpoint (ICP) proteins. These ICPs paralyze immune effector cells and thereby enable unfettered tumor growth. Monoclonal antibodies (mAbs) that block ICPs can prevent immune exhaustion. Due to their outstanding effects, mAbs revolutionized the field of cancer immunotherapy. However, current ICP therapy regimens suffer from issues related to systemic administration of mAbs, including the onset of immune related adverse events, poor pharmacokinetics, limited tumor accessibility and immunogenicity. These drawbacks and new insights on spatiality prompted the exploration of novel administration routes for mAbs for instance peritumoral delivery. Moreover, novel ICP drug classes that are adept to novel delivery technologies were developed to circumvent the drawbacks of mAbs. We therefore review the state-of-the-art and novel delivery strategies of ICP drugs.

Supramolecular assembly of a trivalent peptide hydrogel vaccine for cancer immunotherapy

Vaccination shows great promise in cancer immunotherapy. However, the induction of robust and broad therapeutic CD8 T cell immunity against tumors is challenging due to the essential heterogenicity of tumor antigen expression. Recently, bioinspired materials have reshaped the field of cancer nanomedicine. Herein, a bioinspired nanofibrous trivalent peptide hydrogel vaccine was constructed using the spontaneous supramolecular co-assembly of three antigenic epitope-conjugated peptides, which could mimic the fibrillar structure and biological function of the extracellular matrix and naturally occurring protein assembly. The hydrogel vaccine could be accurately and flexibly adjusted to load each antigenic peptide at a defined ratio, which facilitated the antigen presentation of dendritic cells and significantly improved the initiation of CD8 T cell response and the secretion of interferon-γ (IFN-γ). C57BL/6 mice were immunized with the trivalent peptide hydrogel vaccine, where it elicited a high broad-spectrum antitumor CD8 T cell response that significantly inhibited the growth of B16 tumors in the absence of additional immunoadjuvants or delivery systems. In summary, the supramolecular assembly of triple antigenic epitope-conjugated peptides offers a simple, customizable, and versatile approach for the development of cancer vaccines with remarkable therapeutic efficacy, thereby providing a highly versatile platform for the application of personalized multivalent tumor vaccines. STATEMENT OF SIGNIFICANCE: (1) We report a feasible, versatile and bioinspired approach to manufacture a multivalent peptide-based hydrogel cancer vaccine in the absence of additional adjuvants, which closely mimics immune niches, co-delivers antigen epitopes, greatly promotes antigen presentation to DCs and their subsequent homing to dLNs and elicits a broad-spectrum antitumor CD8 T cell response, resulting in significant inhibition of B16 tumor growth. (2) This feasible and efficient co-assembly strategy provides an attractive platform for engineering a range of multivalent vaccines at defined ratios to further enhance antigen-specific T cell responses. This approach may also be used for personalized immunotherapy with neo-epitopes.

Quaternary Ammonium Salts: Insights into Synthesis and New Directions in Antibacterial Applications

The overuse of antibiotics has led to the emergence of a large number of antibiotic-resistant genes in bacteria, and increasing evidence indicates that a fungicide with an antibacterial mechanism different from that of antibiotics is needed. Quaternary ammonium salts (QASs) are a biparental substance with good antibacterial properties that kills bacteria through simple electrostatic adsorption and insertion into cell membranes/altering of cell membrane permeability. Therefore, the probability of bacteria developing drug resistance is greatly reduced. In this review, we focus on the synthesis and application of single-chain QASs, double-chain QASs, heterocyclic QASs, and gemini QASs (GQASs). Some possible structure-function relationships of QASs are also summarized. As such, we hope this review will provide insight for researchers to explore more applications of QASs in the field of antimicrobials with the aim of developing systems for clinical applications.

Application of injectable hydrogels in cancer immunotherapy

Immunotherapy is a revolutionary and promising approach to cancer treatment. However, traditional cancer immunotherapy often has the disadvantages of limited immune response rate, poor targeting, and low treatment index due to systemic administration. Hydrogels are drug carriers with many advantages. They can be loaded and transported with immunotherapeutic agents, chemical anticancer drugs, radiopharmaceuticals, photothermal agents, photosensitizers, and other therapeutic agents to achieve controlled release of drugs, extend the retention time of drugs, and thus successfully trigger anti-tumor effects and maintain long-term therapeutic effects after administration. This paper reviews recent advances in injectable hydrogel-based cancer immunotherapy, including immunotherapy alone, immunotherapy with combination chemotherapy, radiotherapy, phototherapy, and DNA hydrogel-based immunotherapy. Finally, we review the potential and limitations of injectable hydrogels in cancer immunotherapy.

Recent Advances in Cancer Immunotherapy Delivery Modalities

Immunotherapy is crucial in fighting cancer and achieving successful remission. Many novel strategies have recently developed, but there are still some obstacles to overcome before we can effectively attack the cancer cells and decimate the cancer environment by inducing a cascade of immune responses. To successfully demonstrate antitumor activity, immune cells must be delivered to cancer cells and exposed to the immune system. Such cutting-edge technology necessitates meticulously designed delivery methods with no loss or superior homing onto cancer environments, as well as high therapeutic efficacy and fewer adverse events. In this paper, we discuss recent advances in cancer immunotherapy delivery techniques, as well as their future prospects.

Leading Edge: Intratumor Delivery of Monoclonal Antibodies for the Treatment of Solid Tumors

Immunotherapies based on immune checkpoint blockade have shown remarkable clinical outcomes and durable responses in patients with many tumor types. Nevertheless, these therapies lack efficacy in most cancer patients, even causing severe adverse events in a small subset of patients, such as inflammatory disorders and hyper-progressive disease. To diminish the risk of developing serious toxicities, intratumor delivery of monoclonal antibodies could be a solution. Encouraging results have been shown in both preclinical and clinical studies. Thus, intratumor immunotherapy as a new strategy may retain efficacy while increasing safety. This approach is still an exploratory frontier in cancer research and opens up new possibilities for next-generation personalized medicine. Local intratumor delivery can be achieved through many means, but an attractive approach is the use of gene therapy vectors expressing mAbs inside the tumor mass. Here, we summarize basic, translational, and clinical results of intratumor mAb delivery, together with descriptions of non-viral and viral strategies for mAb delivery in preclinical and clinical development. Currently, this is an expanding research subject that will surely play a key role in the future of oncology.

Locoregional Lymphatic Delivery Systems Using Nanoparticles and Hydrogels for Anticancer Immunotherapy

The lymphatic system has gained significant interest as a target tissue to control cancer progress, which highlights its central role in adaptive immune response. Numerous mechanistic studies have revealed the benefits of nano-sized materials in the transport of various cargos to lymph nodes, overcoming barriers associated with lymphatic physiology. The potential of sustained drug delivery systems in improving the therapeutic index of various immune modulating agents is also being actively discussed. Herein, we aim to discuss design rationales and principles of locoregional lymphatic drug delivery systems for invigorating adaptive immune response for efficient antitumor immunotherapy and provide examples of various advanced nanoparticle- and hydrogel-based formulations.

Engineered tumor cell-derived vaccines against cancer: The art of combating poison with poison

Tumor vaccination is a promising approach for tumor immunotherapy because it presents high specificity and few side effects. However, tumor vaccines that contain only a single tumor antigen can allow immune system evasion by tumor variants. Tumor antigens are complex and heterogeneous, and identifying a single antigen that is uniformly expressed by tumor cells is challenging. Whole tumor cells can produce comprehensive antigens that trigger extensive tumor-specific immune responses. Therefore, tumor cells are an ideal source of antigens for tumor vaccines. A better understanding of tumor cell-derived vaccines and their characteristics, along with the development of new technologies for antigen delivery, can help improve vaccine design. In this review, we summarize the recent advances in tumor cell-derived vaccines in cancer immunotherapy and highlight the different types of engineered approaches, mechanisms, administration methods, and future perspectives. We discuss tumor cell-derived vaccines, including whole tumor cell components, extracellular vesicles, and cell membrane-encapsulated nanoparticles. Tumor cell-derived vaccines contain multiple tumor antigens and can induce extensive and potent tumor immune responses. However, they should be engineered to overcome limitations such as insufficient immunogenicity and weak targeting. The genetic and chemical engineering of tumor cell-derived vaccines can greatly enhance their targeting, intelligence, and functionality, thereby realizing stronger tumor immunotherapy effects. Further advances in materials science, biomedicine, and oncology can facilitate the clinical translation of tumor cell-derived vaccines.

Chemical and Synthetic Biology Approaches for Cancer Vaccine Development

Cancer vaccines have been considered promising therapeutic strategies and are often constructed from whole cells, attenuated pathogens, carbohydrates, peptides, nucleic acids, etc. However, the use of whole organisms or pathogens can elicit unwanted immune responses arising from unforeseen reactions to the vaccine components. On the other hand, synthetic vaccines, which contain antigens that are conjugated, often with carrier proteins, can overcome these issues. Therefore, in this review we have highlighted the synthetic approaches and discussed several bioconjugation strategies for developing antigen-based cancer vaccines. In addition, the major synthetic biology approaches that were used to develop genetically modified cancer vaccines and their progress in clinical research are summarized here. Furthermore, to boost the immune responses of any vaccines, the addition of suitable adjuvants and a proper delivery system are essential. Hence, this review also mentions the synthesis of adjuvants and utilization of biomaterial scaffolds, which may facilitate the design of future cancer vaccines.

Gadolinium-based ultra-small nanoparticles augment radiotherapy-induced T-cell response to synergize with checkpoint blockade immunotherapy

Radiotherapy suffers from its high-dose radiation-induced systemic toxicity and radioresistance caused by the immunosuppressive tumor microenvironment. Immunotherapy using checkpoint blocking in solid tumors shows limited anticancer efficacy due to insufficient T-cell infiltration and inadequate systemic immune responses. Activation and guiding of irradiation by X-ray (AGuIX) nanoparticles with sizes below 5 nm have entered a phase III clinical trial as efficient radiosensitizers. This study aimed to develop a unique synergistic strategy based on AGuIX-mediated radiotherapy and immune checkpoint blockade to further improve the efficiency for B16 tumor therapy. AGuIX exacerbated radiation-induced DNA damage, cell cycle arrest, and apoptosis on B16 cells. More importantly, it could efficiently induce the immunogenic cell death of irradiated B16 tumor cells, and consequently trigger the maturation of dendritic cells and activation of systemic T-cell responses. Combining AGuIX-mediated radiotherapy with programmed cell death protein 1 blockade demonstrated excellent synergistic therapeutic effects in both bilateral and metastatic B16 tumor models, as indicated by a significant increase in the infiltration of effector CD8⁺ T cells and effective alleviation of the immunosuppressive tumor microenvironment. Our findings indicate that the synergy between radiosensitization and immunomodulation provides a new and powerful therapy regimen to achieve durable antitumor T-cell responses, which is promising for cancer treatment.

A Shear-Thinning Biomaterial-Mediated Immune Checkpoint Blockade

Systemic administration of immune checkpoint blockade agents can activate the anticancer activity of immune cells; however, the response varies from patient to patient and presents potential off-target toxicities. Local administration of immune checkpoint inhibitors (ICIs) can maximize therapeutic efficacies while reducing side effects. This study demonstrates a minimally invasive strategy to locally deliver anti-programmed cell death protein 1 (anti-PD-1) with shear-thinning biomaterials (STBs). ICI can be injected into tumors when loaded in STBs (STB-ICI) composed of gelatin and silicate nanoplatelets (Laponite). The release of ICI from STB was mainly affected by the Laponite percentage in STBs and pH of the local microenvironment. Low Laponite content and acidic pH can induce ICI release. In a murine melanoma model, the injection of STB-ICI significantly reduced tumor growth and increased CD8⁺ T cell level in peripheral blood. STB-ICI also induced increased levels of tumor-infiltrating CD4⁺ helper T cells, CD8⁺ cytotoxic T cells, and tumor death. The STB-based minimally invasive strategy provides a simple and efficient approach to deliver ICIs locally.

Self-Healing Injectable Hydrogels for Tissue Regeneration

Biomaterials with the ability to self-heal and recover their structural integrity offer many advantages for applications in biomedicine. The past decade has witnessed the rapid emergence of a new class of self-healing biomaterials commonly termed injectable, or printable in the context of 3D printing. These self-healing injectable biomaterials, mostly hydrogels and other soft condensed matter based on reversible chemistry, are able to temporarily fluidize under shear stress and subsequently recover their original mechanical properties. Self-healing injectable hydrogels offer distinct advantages compared to traditional biomaterials. Most notably, they can be administered in a locally targeted and minimally invasive manner through a narrow syringe without the need for invasive surgery. Their moldability allows for a patient-specific intervention and shows great prospects for personalized medicine. Injected hydrogels can facilitate tissue regeneration in multiple ways owing to their viscoelastic and diffusive nature, ranging from simple mechanical support, spatiotemporally controlled delivery of cells or therapeutics, to local recruitment and modulation of host cells to promote tissue regeneration. Consequently, self-healing injectable hydrogels have been at the forefront of many cutting-edge tissue regeneration strategies. This study provides a critical review of the current state of self-healing injectable hydrogels for tissue regeneration. As key challenges toward further maturation of this exciting research field, we identify (i) the trade-off between the self-healing and injectability of hydrogels vs their physical stability, (ii) the lack of consensus on rheological characterization and quantitative benchmarks for self-healing injectable hydrogels, particularly regarding the capillary flow in syringes, and (iii) practical limitations regarding translation toward therapeutically effective formulations for regeneration of specific tissues. Hence, here we (i) review chemical and physical design strategies for self-healing injectable hydrogels, (ii) provide a practical guide for their rheological analysis, and (iii) showcase their applicability for regeneration of various tissues and 3D printing of complex tissues and organoids.

Activation of Cellular Players in Adaptive Immunity via Exogenous Delivery of Tumor Cell Lysates

Tumor cell lysates (TCLs) are a good immunogenic source of tumor-associated antigens. Since whole necrotic TCLs can enhance the maturation and antigen-presenting ability of dendritic cells (DCs), multiple strategies for the exogenous delivery of TCLs have been investigated as novel cancer immunotherapeutic solutions. The TCL-mediated induction of DC maturation and the subsequent immunological response could be improved by utilizing various material-based carriers. Enhanced antitumor immunity and cancer vaccination efficacy could be eventually achieved through the in vivo administration of TCLs. Therefore, (1) important engineering methodologies to prepare antigen-containing TCLs, (2) current therapeutic approaches using TCL-mediated DC activation, and (3) the significant sequential mechanism of DC-based signaling and stimulation in adaptive immunity are summarized in this review. More importantly, the recently reported developments in biomaterial-based exogenous TCL delivery platforms and co-delivery strategies with adjuvants for effective cancer vaccination and antitumor effects are emphasized.

Local scaffold-assisted delivery of immunotherapeutic agents for improved cancer immunotherapy

Cancer immunotherapy, which reprograms a patient's own immune system to eradicate cancer cells, has been demonstrated as a promising therapeutic strategy clinically. Immune checkpoint blockade (ICB) therapies, cytokine therapies, cancer vaccines, and chimeric antigen receptor (CAR) T cell therapies utilize immunotherapy techniques to relieve tumor immune suppression and/or activate cellular immune responses to suppress tumor growth, metastasis and recurrence. However, systemic administration is often hampered by limited drug efficacy and adverse side effects due to nonspecific tissue distribution of immunotherapeutic agents. Advancements in local scaffold-based delivery systems facilitate a controlled release of therapeutic agents into specific tissue sites through creating a local drug reservoir, providing a potent strategy to overcome previous immunotherapy limitations by improving site-specific efficacy and minimizing systemic toxicity. In this review, we summarized recent advances in local scaffold-assisted delivery of immunotherapeutic agents to reeducate the immune system, aiming to amplify anticancer efficacy and minimize immune-related adverse events. Additionally, the challenges and future perspectives of local scaffold-assisted cancer immunotherapy for clinical translation and applications are discussed.

NIR Responsive Injectable Nanocomposite Thermogel System Against Osteosarcoma Recurrence

Compared to traditional postoperative radiation and chemotherapy, immune checkpoint blockade (ICB) therapy demonstrates superiority by provoking own immune system to cure cancer completely even for some terminally ill patients. However, systemic administration of ICB is liable to cause severe immunity inflammation or immune storm. Here we propose an injectable, near infrared (NIR) responsive, multifunctional nanocomposite thermogel as a local ICB delivery system for cancer postsurgical therapy. By copolymerization of thermosensitive and zwitterionic monomer, the injectable thermogel with adjustable sol-gel transition temperature is obtained. Afterwards, combined with functional mesoporous nanoparticles, the platform could absorb NIR light and transfer it into heat. The generated heat will promote retro Diels-Alder reaction to degrade coating layer on nanoparticle, achieving NIR controlled ICB release. Furthermore, the local ICB delivery system is applied on an osteosarcoma postsurgical recurrence model and results indicate the platform with favorable biocompatibility could avoid early leakage of cargos and greatly increase drug content at tumor site. Besides, long-term controlled ICB release of the system effectively improve the amount of active T cells, resulting in excellent anti-tumor recurrence effect. Overall, this work suggests the local injectable nanocomposite thermogel is expected to be a promising tool for cancer postoperative therapy. This article is protected by copyright. All rights reserved.

3D-Printable Oxygen- and Drug-Carrying Nanocomposite Hydrogels for Enhanced Cell Viability

Nanocomposite (NC) hydrogels have been widely studied due to their tunable biochemical/ physical properties for tissue engineering and biomedical applications. Nanoparticles (NPs) that can carry bioactive hydrophilic/hydrophobic molecules and provide sustained release within hydrogels are an ideal all-in-one-platform for local drug delivery applications. Dual delivery of different bioactive molecules is desired to achieve synergetic therapeutic effect in biomedical applications. For example, the co-administration of drug molecules and oxygen (O₂) is an ideal choice to improve cell viability, while reducing the harmful effects of hypoxia. Therefore, we prepared drug-loaded O₂-carrying periodic mesoporous organosilica (PMO-PFC) NPs and their 3D-printable hydrogel precursors based on gelatin methacryloyl (GelMa) to fabricate 3D-scaffolds to improve cell-viability under both normoxia (21% O₂) and hypoxia (1% O₂) conditions. We used rutin as the hydrophobic drug molecule to demonstrate that our O₂-carrying PMO-PFC NPs can improve hydrophobic drug loading and their sustained delivery over 7 days, while supporting sustained O₂-delivery for 14 days under hypoxia conditions. Furthermore, the fibroblast cells were interacted with NC hydrogel scaffolds to test their impact on cell-viability under both normoxia and hypoxia conditions. The improved rheological properties suggest the prepared NC hydrogels can be further tested or used as an injectable hydrogel. The improved mechanical properties and 3D printability of NC hydrogels indicate their potential use as artificial tissue constructs.

Antigen epitope-TLR7/8a conjugate as self-assembled carrier-free nanovaccine for personalized immunotherapy

Epitope-based vaccine is a promising personalized cancer immunotherapy; however, a simple and effective approach for its bulk manufacturing is challenging. Current vaccination strategies complicate the process by introducing unnecessary components such as additional delivery carriers, and assembly units. Herein, a type of toll-like receptor 7/8 agonist-epitope conjugate (termed as TLR7/8a-epitope) has been developed as a self-assembled and carrier-free nano vaccine platform, which effectively introduces the antigen and adjuvant with maximum precision, resulting in significantly enhanced dendritic cells (DCs) activation through the MyD88-dependent TLR signaling pathway. TLR7/8a-epitope nanovaccine can prolong the local retention and increase drainage efficiency into the lymph node, eliciting a significantly higher level of CD8 T-cell immunity than those of conventional vaccine formulations. The immunization with TLR7/8a-epitope nanovaccine in mice can not only resist the invasion of B16 cancer cells, but also produce significant therapeutic effects against established B16 melanoma tumors. Therefore, the TLR7/8a-epitope nanovaccine, developed by the direct chemical conjugation of antigen peptide with immunoadjuvant, has great advantages of clear and leanest compositions, controllable and definite preparation process, and remarkable therapeutic effects, representing a new appraoch for personalized cancer immunotherapy. STATEMENT OF SIGNIFICANCE: Herein, a kind of toll-like receptor 7/8 agonist-epitope conjugate was developed and spontaneously self-assemble into nanostructure in aqueous solution without the use of any additional constituents, which can be termed as unique carrier-free nanovaccine platform, providing effectually the leanest vaccine components with maximally and precisely loading of antigen and adjuvant. Significantly, the nanovaccine augmented the immunogenicity of antigenic peptide by increasing DCs activation through MyD88-mediated TLR signaling pathways and promoting T-cell priming. Moreover, nanovaccines could prolong the local retention and further increase the efficiency of drainage into dLNs, which was contributing to efficient initiation of epitope-specific memory and effector T-cell immune responses, leading to effective prophylactic and therapeutic antitumor effects.

Injectable Hydrogel as a Unique Platform for Antitumor Therapy Targeting Immunosuppressive Tumor Microenvironment

Cancer immunotherapy can boost the immune response of patients to eliminate tumor cells and suppress tumor metastasis and recurrence. However, immunotherapy resistance and the occurrence of severe immune-related adverse effects are clinical challenges that remain to be addressed. The tumor microenvironment plays a crucial role in the therapeutic efficacy of cancer immunotherapy. Injectable hydrogels have emerged as powerful drug delivery platforms offering good biocompatibility and biodegradability, minimal invasion, convenient synthesis, versatility, high drug-loading capacity, controlled drug release, and low toxicity. In this review, we summarize the application of injectable hydrogels as a unique platform for targeting the immunosuppressive tumor microenvironment.

Supramolecular biomaterials for enhanced cancer immunotherapy

Cancer immunotherapy has achieved promising clinical results. However, many limitations associated with current cancer immunotherapy still exist, including low response rates and severe adverse effects in patients. Engineering biomaterials for...

Bionic Biphasic Composite Scaffold with Osteochondrogenic Factors for Regeneration of Full-Thickness Osteochondral Defect

Full-thickness osteochondral defects lack the capability to self-repair owing to their complicated hierarchical structure. At present, clinical treatments including microfracture etc. have shown some efficacy; however, the newborn tissue exhibits...

Emerging biomaterial-based strategies for personalized therapeutic in situ cancer vaccines

Landmark successes in oncoimmunology have led to development of therapeutics boosting the host immune system to eradicate local and distant tumors with impactful tumor reduction in a subset of patients. However, current immunotherapy modalities often demonstrate limited success when involving immunologically cold tumors and solid tumors. Here, we describe the role of various biomaterials to formulate cancer vaccines as a form of cancer immunotherapy, seeking to utilize the host immune system to activate and expand tumor-specific T cells. Biomaterial-based cancer vaccines enhance the cancer-immunity cycle by harnessing cellular recruitment and activation against tumor-specific antigens. In this review, we discuss biomaterial-based vaccine strategies to induce lymphocytic responses necessary to mediate anti-tumor immunity. We focus on strategies that selectively attract dendritic cells via immunostimulatory gradients, activate them against presented tumor-specific antigens, and induce effective cross-presentation to T cells in secondary lymphoid organs, thereby generating immunity. We posit that personalized cancer vaccines are promising targets to generate long-term systemic immunity against patient- and tumor-specific antigens to ensure long-term cancer remission.

3D Printing Scaffold Vaccine for Antitumor Immunity

Cancer vaccine platform has attracted great interest in the field of cancer immunotherapy. Here, 3D printed scaffolds loaded with immunoregulators are developed for enhanced cancer immunotherapy. The rapid manufacturing and precise molding based on 3D printing can realize the mass manufacturing of cancer vaccines and personalized design. Meanwhile, compared to the traditional hydrogel, the 3D-scaffold with porous structure endows its similar functions compared with real lymphoid organs by recruitment of a great number of immune cells, leading to the formation of "artificial tertiary lymphoid structures," where there is a promising site to enhance both humoral and cellular immune responses. Efficient anticancer immunity is induced when combined with immune checkpoint blockade to inhibit the tumor growth. Personalized antitumor scaffold vaccines are further demonstrated for filling of tumor site after surgery to prevent cancer metastasis. Taken together, these results promise the 3D printing scaffold vaccine as the potential strategy for cancer vaccine therapy in the future.

Locally Injectable Hydrogels for Tumor Immunotherapy

Hydrogel-based local delivery systems provide a good delivery platform for cancer immunotherapy. Injectable hydrogels can directly deliver antitumor drugs to the tumor site to reduce systemic toxicity and achieve low-dose amplification immunotherapy. Therefore, it may overcome the problems of low drug utilization rate and the systemic side effects in cancer immunotherapy through systemic immune drugs, and it provides simple operation and little invasion at the same time. This study aimed to review the research progress of injectable hydrogels in tumor immunotherapy in recent years. Moreover, the local delivery of multiple drugs using injectable hydrogels in tumors is introduced to achieve single immunotherapy, combined chemo-immunotherapy, combined radio-immunotherapy, and photo-immunotherapy. Finally, the application of hydrogels in tumor immunotherapy is summarized, and the challenges and prospects for injectable hydrogels in tumor immunotherapy are proposed.