Enhancing T cell therapy through TCR-signaling-responsive nanoparticle drug delivery

A supramolecular protein chaperone for vaccine delivery

Rationale: Nanomaterials capable of specifically interacting with proteins are very important for protein storage and vaccine delivery. Supramolecular hydrogels based on peptides have emerged as promising vaccine adjuvants because of their good compatibility, ease of antigen incorporation and display, and efficiency in activating immune responses. Methods: We synthesized a self-assembling peptide (Fbp-GDFDFDYDK(γE)2-NH2, Comp. 1 ) serving as a supramolecular protein chaperone for protein antigen delivery. The gelation was triggered by simply mixing Comp. 1 and proteins. The vaccine adjuvant potential of Comp. 1 was demonstrated by using two protein antigens, ovalbumin (OVA) and hepatitis B surface antigen (HBsAg). Results: The peptide derivative Comp. 1 exhibited high protein binding capacity. Upon contacting proteins, Comp. 1 rapidly formed coassembled nanofibers/hydrogels with the proteins, which greatly delayed the release of protein antigens. Our supramolecular protein chaperone significantly stimulated specific antibody titers by assisting protein delivery to antigen-presenting cells, promoting dendritic cell (DC) maturation, prolonging antigen accumulation and retention in the lymph nodes, and eliciting the secretion of cytokines. Most importantly, our supramolecular protein chaperone strongly stimulated the cellular immune response and significantly retarded tumor growth. Conclusion: Our study demonstrated the great potential of the supramolecular protein chaperone in protein storage and delivery, vaccine production and tumor immunotherapy.

CAR T Cell Therapy Progress and Challenges for Solid Tumors

The past two decades have marked the beginning of an unprecedented success story for cancer therapy through redirecting antitumor immunity [1]. While the mechanisms that control the initial and ongoing immune responses against tumors remain a strong research focus, the clinical development of technologies that engage the immune system to target and kill cancer cells has become a translational research priority. Early attempts documented in the late 1800s aimed at sparking immunity with cancer vaccines were difficult to interpret but demonstrated an opportunity that more than 100 years later has blossomed into the current field of cancer immunotherapy. Perhaps the most recent and greatest illustration of this is the widespread appreciation that tumors actively shut down antitumor immunity, which has led to the emergence of checkpoint pathway inhibitors that re-invigorate the body's own immune system to target cancer [2, 3]. This class of drugs, with first FDA approvals in 2011, has demonstrated impressive durable clinical responses in several cancer types, including melanoma, lung cancer, Hodgkin's lymphoma, and renal cell carcinoma, with the ongoing investigation in others. The biology and ultimate therapeutic successes of these drugs led to the 2018 Nobel Prize in Physiology or Medicine, awarded to Dr. James Allison and Dr. Tasuku Honjo for their contributions to cancer therapy [4]. In parallel to the emerging science that aided in unleashing the body's own antitumor immunity with checkpoint pathway inhibitors, researchers were also identifying ways to re-engineer antitumor immunity through adoptive cellular immunotherapy approaches. Chimeric antigen receptor (CAR)-based T cell therapy has achieved an early head start in the field, with two recent FDA approvals in 2017 for the treatment of B-cell malignancies [5]. There is an explosion of preclinical and clinical efforts to expand the therapeutic indications for CAR T cell therapies, with a specific focus on improving their clinical utility, particularly for the treatment of solid tumors. In this chapter, we will highlight the recent progress, challenges, and future perspectives surrounding the development of CAR T cell therapies for solid tumors.

Molecular and nanoengineering approaches towards activatable cancer immunotherapy

This review summarizes the development of activatable immunotherapeutic nanoagents that activate antitumor immunity only in response to internal or external stimuli, which potentially enhance patient response rates while reducing immune-related adverse events during cancer immunotherapy.

Engineering strategies to overcome the current roadblocks in CAR T cell therapy

T cells genetically engineered to express chimeric antigen receptors (CARs) have proven — and impressive — therapeutic activity in patients with certain subtypes of B cell leukaemia or lymphoma, with promising efficacy also demonstrated in patients with multiple myeloma. Nevertheless, various barriers restrict the efficacy and/or prevent the widespread use of CAR T cell therapies in these patients as well as in those with other cancers, particularly solid tumours. Key challenges relating to CAR T cells include severe toxicities, restricted trafficking to, infiltration into and activation within tumours, suboptimal persistence in vivo, antigen escape and heterogeneity, and manufacturing issues. The evolution of CAR designs beyond the conventional structures will be necessary to address these limitations and to expand the use of CAR T cells to a wider range of malignancies. Investigators are addressing the current obstacles with a wide range of engineering strategies in order to improve the safety, efficacy and applicability of this therapeutic modality. In this Review, we discuss the innovative designs of novel CAR T cell products that are being developed to increase and expand the clinical benefits of these treatments in patients with diverse cancers.

Chimeric antigen receptor (CAR) T cell therapy, the first approved therapeutic approach with a genetic engineering component, holds substantial promise in the treatment of a range of cancers but is nevertheless limited by various challenges, including toxicities, intrinsic and acquired resistance mechanisms, and manufacturing issues. In this Review, the authors describe the innovative approaches to the engineering of CAR T cell products that are providing solutions to these challenges and therefore have the potential to considerably improve the safety and effectiveness of treatment.

Chimeric antigen receptor (CAR) T cells have induced remarkable responses in patients with certain haematological malignancies, yet various barriers restrict the efficacy and/or prevent the widespread use of this treatment.

Investigators are addressing these challenges with engineering strategies designed to improve the safety, efficacy and applicability of CAR T cell therapy.

CARs have modular components, and therefore the optimal molecular design of the CAR can be achieved through many variations of the constituent protein domains.

Toxicities currently associated with CAR T cell therapy can be mitigated using engineering strategies to make CAR T cells safer and that potentially broaden the range of tumour-associated antigens that can be targeted by overcoming on-target, off-tumour toxicities.

CAR T cell efficacy can be enhanced by using engineering strategies to address the various challenges relating to the unique biology of diverse haematological and solid malignancies.

Strategies to address the manufacturing challenges can lead to an improved CAR T cell product for all patients.

Metabolic interventions in the immune response to cancer

At the centre of the therapeutic dilemma posed by cancer is the question of how to develop more effective treatments that discriminate between normal and cancerous tissues. Decades of research have shown us that universally applicable principles are rare, but two well-accepted concepts have emerged: first, that malignant transformation goes hand in hand with distinct changes in cellular metabolism; second, that the immune system is critical for tumour control and clearance. Unifying our understanding of tumour metabolism with immune cell function may prove to be a powerful approach in the development of more effective cancer therapies. Here, we explore how nutrient availability in the tumour microenvironment shapes immune responses and identify areas of intervention to modulate the metabolic constraints placed on immune cells in this setting.

Advances on Non-Genetic Cell Membrane Engineering for Biomedical Applications

Cell-based therapeutics are very promising modalities to address many unmet medical needs, including genetic engineering, drug delivery, and regenerative medicine as well as bioimaging. To enhance the function and improve the efficacy of cell-based therapeutics, a variety of cell surface engineering strategies (genetic engineering and non-genetic engineering) are developed to modify the surface of cells or cell-based therapeutics with some therapeutic molecules, artificial receptors, and multifunctional nanomaterials. In comparison to complicated procedures and potential toxicities associated with genetic engineering, non-genetic engineering strategies have emerged as a powerful and compatible complement to traditional genetic engineering strategies for enhancing the function of cells or cell-based therapeutics. In this review, we will first briefly summarize key non-genetic methodologies including covalent chemical conjugation (surface reactive groups-direct conjugation, and enzymatically mediated and metabolically mediated indirect conjugation) and noncovalent physical bioconjugation (biotinylation, electrostatic interaction, and lipid membrane fusion as well as hydrophobic insertion), which have been developed to engineer the surface of cell-based therapeutics with various materials. Next, we will comprehensively highlight the latest advances in non-genetic cell membrane engineering surrounding different cells or cell-based therapeutics, including whole-cell-based therapeutics, cell membrane-derived therapeutics, and extracellular vesicles. Advances will be focused specifically on cells that are the most popular types in this field, including erythrocytes, platelets, cancer cells, leukocytes, stem cells, and bacteria. Finally, we will end with the challenges, future trends, and our perspectives of this relatively new and fast-developing research field.

Nanomedicine-Based Immunotherapy for the Treatment of Cancer Metastasis

Metastasis is the leading cause of cancer-associated death, with poor prognosis even after extensive treatment. The dormancy of metastatic cancer cells during dissemination or after colony formation is one major reason for treatment failure, as most drugs target cells of active proliferation. Immunotherapy has shown great potential in cancer therapy because the activity of effector cells is less affected by the metabolic status of cancer cells. In addition, metastatic cells out of immunosuppressive tumor microenvironment (TME) are more susceptible to immune clearance, although these cells can achieve immune surveillance evasion via strategies such as platelet and macrophage recruitment. Since nanomaterials themselves or their carried drugs have the capability to modulate the immune system, a great amount of focus has been placed on nanomedicine strategies that leverage immune cells participating the metastatic cascade. These nanomedicines successfully inhibit the tumor metastasis and prolong the survival of model animals. Immune cells that are involved in the metastasis cascade are first summarized and then recent and inspiring strategies and nanomaterials in this growing field are highlighted.

Disulfide-Based Self-Immolative Linkers and Functional Bioconjugates for Biological Applications

It is of vital importance to reversibly mask and selectively activate bioactive agents for advanced therapeutic and diagnostic purposes, aiming to efficiently suppress background interferences and attenuate systemic toxicity. This strategy has been involved in diverse applications spanning from chemical/biological sensors and diagnostics to drug delivery nanocarriers. Among these, redox-responsive disulfide linkages have been extensively utilized by taking advantage of extracellular and intracellular glutathione (GSH) gradients. However, direct conjugation of cleavable triggers to bioactive agents through disulfide bonds suffers from bulky steric hindrance and limited choice of trigger-drug combinations. Fortunately, the emergence of disulfide self-immolative linkers (DSILs) provides a general and robust strategy to not only mask various bioactive agents through the formation of dynamic disulfide linkages but also make it possible to be selectively activated upon disulfide cleavage in the reductive cytoplasmic milieu. In this review, recent developments in DSILs are focused with special attention on emerging chemical design strategies and functional applications in the biomedical field.

Near-Infrared Photoactivatable Semiconducting Polymer Nanoblockaders for Metastasis-Inhibited Combination Cancer Therapy

Inhibition of protein biosynthesis is a promising strategy to develop new therapeutic modalities for cancers; however, noninvasive precise regulation of this cellular event in living systems has been rarely reported. In this study, a semiconducting polymer nanoblockader (SPN_B ) is developed that can inhibit intracellular protein synthesis upon near-infrared (NIR) photoactivation to synergize with photodynamic therapy (PDT) for metastasis-inhibited cancer therapy. SPN_B is self-assembled from an amphiphilic semiconducting polymer which is grafted with poly(ethylene glycol) conjugated with a protein biosynthesis blockader through a singlet oxygen (¹ O₂ ) cleavable linker. Such a designed molecular structure not only enables generation of ¹ O₂ under NIR photoirradiation for PDT, but also permits photoactivation of blockaders to terminate protein translation. Thereby, SPN_B exerts a synergistic action to afford an enhanced therapeutic efficacy in tumor ablation. More importantly, SPN_B -mediated photoactivation of protein synthesis inhibition precisely and remotely downregulates the expression levels of metastasis-related proteins in tumor tissues, eventually contributing to the complete inhibition of lung metastasis. This study thus proposes a photoactivatable protherapeutic design for metastasis-inhibited cancer therapy.

Advances in nanomedicine for cancer starvation therapy

Abnormal cell metabolism with vigorous nutrition consumption is one of the major physiological characteristics of cancers. As such, the strategy of cancer starvation therapy through blocking the blood supply, depleting glucose/oxygen and other critical nutrients of tumors has been widely studied to be an attractive way for cancer treatment. However, several undesirable properties of these agents, such as low targeting efficacy, undesired systemic side effects, elevated tumor hypoxia, induced drug resistance, and increased tumor metastasis risk, limit their future applications. The recent development of starving-nanotherapeutics combined with other therapeutic methods displayed the promising potential for overcoming the above drawbacks. This review highlights the recent advances of nanotherapeutic-based cancer starvation therapy and discusses the challenges and future prospects of these anticancer strategies.

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.

Advances in Engineering Cells for Cancer Immunotherapy

Cancer immunotherapy aims to utilize the host immune system to kill cancer cells. Recent representative immunotherapies include T-cell transfer therapies, such as chimeric antigen receptor T cell therapy, antibody-based immunomodulator therapies, such as immune checkpoint blockade therapy, and cytokine therapies. Recently developed therapies leveraging engineered cells for immunotherapy against cancers have been reported to enhance antitumor efficacy while reducing side effects. Such therapies range from biologically, chemically and physically -engineered cells to bioinspired and biomimetic nanomedicines. In this review, advances of engineering cells for cancer immunotherapy are summarized, and prospects of this field are discussed.

Improving cancer immunotherapy through nanotechnology

The 2018 Nobel Prize in Physiology or Medicine was awarded to pioneers in the field of cancer immunotherapy, as the utility of leveraging a patient's coordinated and adaptive immune system to fight the patient's unique tumour has now been validated robustly in the clinic. Still, the proportion of patients who respond to immunotherapy remains modest (~15% objective response rate across indications), as tumours have multiple means of immune evasion. The immune system is spatiotemporally controlled, so therapies that influence the immune system should be spatiotemporally controlled as well, in order to maximize the therapeutic index. Nanoparticles and biomaterials enable one to program the location, pharmacokinetics and co-delivery of immunomodulatory compounds, eliciting responses that cannot be achieved upon administration of such compounds in solution. The convergence of cancer immunotherapy, nanotechnology, bioengineering and drug delivery is opportune, as each of these fields has matured independently to the point that it can now be used to complement the others substantively and rationally, rather than modestly and empirically. As a result, unmet needs increasingly can be addressed with deductive intention. This Review explores how nanotechnology and related approaches are being applied to augmenting both endogenous leukocytes and adoptively transferred ones by informing specificity, influencing localization and improving function.

T cell immunotherapy enhanced by designer biomaterials

Cancer immunotherapy has recently burst onto the center stage of cancer treatment and research. T lymphocyte adoptive cellular transfer (ACT), a form of cancer immunotherapy, has spawned unprecedented complete remissions for terminal patients with certain leukemias and lymphomas. Unfortunately, the successes have been overshadowed by the disappointing clinical results of ACT administered to treat solid tumors, in addition to the toxicities associated with the treatment, a lack of efficacy in a significant proportion of the patient population, and cancer relapse following the treatment. Biomaterials hold the promise of addressing these shortcomings. ACT consists of two main stages - T lymphocyte ex vivo expansion followed by reinfusion into the patient - and biomaterials can improve the efficacy of ACT at both stages. In this review, we highlight recent advances in the use of biomaterials for T lymphocyte adoptive cellular cancer immunotherapy and discuss the challenges at each stage.

Advances of functional nanomaterials for cancer immunotherapeutic applications

Immunotherapy has made great progress by modulating the body's own immune system to fight against cancer cells. However, the low response rates of related drugs limit the development of immunotherapy strategies. Fortunately, the advantages of nanotechnology can just make up for this shortcoming. Nanocarriers of diverse systems are utilized to co-deliver antigens and adjuvants, combined with drugs for immunomodulatory, such as chemotherapy, radiotherapy, and photodynamic. Here we review recent studies on immunotherapy with biomimetic, organic, and inorganic nanomaterials. They are going to potentially overcome the drawbacks in cancer immunotherapy with delivering immunomodulatory drugs, delivering cancer vaccine, and monitoring the immune systems. This article is characterized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Enzyme-Instructed Peptide Assemblies Selectively Inhibit Bone Tumors

Alkaline phosphatases (ALP) contribute to immunosuppression in solid tumors, but they, unfortunately, are "undruggable". Here we report enzyme-instructed assembly of peptides for selectively inhibiting the tumors that overexpress ALP. We developed a precursor with two parts; an amphiphilic, self-assembling peptides joined to a hydrophilic block (i.e., tyrosine phosphate). ALP, overexpressed on and in osteosarcoma cancer cells (e.g., Saos-2), cleaves the phosphates from the tyrosine residue of the precursor and triggers the self-assembly of the resulting peptides. Being selectively formed on and inside the cancer cells, the peptide assemblies induce the cancer cell death and efficiently inhibit the tumor growth in an orthotopic osteosarcoma mice model without harming normal organs. Accordingly, the peptide assemblies significantly improve the survival ratio of metastatic tumor bearing mice. Without relying on inhibiting ALP, this approach integrates enzyme reaction and molecular self-assembly for generating peptide fibrils as potential anticancer therapeutics.

Cells and cell derivatives as drug carriers for targeted delivery

For over a century, researchers have focused on how to optimize drug delivery. Systemic administration means that the drug becomes dilute and has the potential to diffuse to all tissues, which is only until the immune system steps in and rapidly clears it from blood circulation. Drug carriers are the solution for amplifying the intended effect and diminishing side effects. With drug carriers, tissue-specific drug delivery and controlled drug release is possible. Thus far, both synthetic and non-synthetic carriers exist. However, due to the numerous limitations of synthetic carriers, science has begun to concentrate on using live cells and cell-derivatives as drug carriers. The most problematic shortcomings of synthetic carriers are their limited biocompatibility and biodegradability. Most synthetic carriers are cytotoxic or induce immune responses. Moreover, synthetic carriers typically depend on passive diffusion and risk phagocytosis, further reducing their impact. On the other hand, live-cell carriers and their derivatives usually have a targeting mechanism and drug release is controlled, increasing the efficiency with which a drug accumulates and acts on a tissue. Still, both types of carriers face similar problems, including achieving high loading capacity, maintaining drug quality, efficiently accumulating in the target tissue, and minimizing side effects. This review aims to elucidate the advantages and disadvantages of each popular cell or cell-derived carrier and to spotlight novel solutions.

Applications of molecular engineering in T-cell-based immunotherapies

Harnessing an individual's immune cells to mediate antitumor and antiviral responses is a life-saving option for some patients with otherwise intractable forms of cancer and infectious disease. In particular, T-cell-based engineered immune cells are a powerful new class of therapeutics with remarkable efficacy. Clinical experience has helped to define some of the major challenges for reliable, safe, and effective deployment of T-cells against a broad range of diseases. While poised to revolutionize immunotherapy, scalable manufacturing, safety, specificity, and the development of resistance are potential roadblocks in their widespread usage. The development of molecular engineering tools to allow for the direct or indirect engineering of T-cells to enable one to troubleshoot delivery issues, amplify immunomodulatory effects, integrate the synergistic effects of different molecules, and home to the target cells in vivo. In this review, we will analyze thus-far developed cell- and material-based tools for enhancing T-cell therapies, including methods to improve safety and specificity, enhancing efficacy, and overcoming limitations in scalable manufacturing. We summarize the potential of T-cells as immune modulating therapies and the potential future directions for enabling their adoption for a broad range of diseases. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Cells at the Nanoscale.

Bioresponsive Protein Complex of aPD1 and aCD47 Antibodies for Enhanced Immunotherapy

Despite the promising efficacy of immune checkpoint blockade (ICB) in treating many types of cancers, the clinical benefits have often been restricted by the low objective response rates and systemic immune-related adverse events. Here, a bioresponsive ICB treatment is developed based on the reactive oxygen species (ROS)-sensitive protein complex for controlled sequential release of anti- "don't eat me" signal antibody (aCD47) and antiprogrammed cell death protein 1 (aPD1), by leveraging the abundant ROS in the tumor microenvironment (TME). These protein complexes can also act as scavengers of ROS in the TME to reverse the immunosuppressive responses, thereby enhancing antitumor efficacy in vivo. In a melanoma cancer model, the synergistic antitumor efficacy was achieved, which was accompanied by enhanced T cell immune responses together with reduced immunosuppressive responses.

Organic Semiconducting Pro-nanostimulants for Near-Infrared Photoactivatable Cancer Immunotherapy

In this study, an organic semiconducting pro-nanostimulant (OSPS) with a near-infrared (NIR) photoactivatable immunotherapeutic action for synergetic cancer therapy is presented. OSPS comprises a semiconducting polymer nanoparticle (SPN) core and an immunostimulant conjugated through a singlet oxygen (¹ O₂ ) cleavable linkers. Upon NIR laser irradiation, OSPS generates both heat and ¹ O₂ to exert combinational phototherapy not only to ablate tumors but also to produce tumor-associated antigens. More importantly, NIR irradiation triggers the cleavage of ¹ O₂ -cleavable linkers, triggering the remote release of the immunostimulants from OSPS to modulate the immunosuppressive tumor microenvironment. Thus, the released tumor-associated antigens in conjunction with activated immunostimulants induce a synergistic antitumor immune response after OSPS-mediated phototherapy, resulting in the inhibited growth of both primary/distant tumors and lung metastasis in a mouse xenograft model, which is not observed for sole phototherapy.

IL-6 and IL-8 secreted by tumour cells impair the function of NK cells via the STAT3 pathway in oesophageal squamous cell carcinoma

Background

Recurrence and metastasis are the leading causes of tumour-related death in patients with oesophageal squamous cell carcinoma (ESCC). Tumour-infiltrating natural killer cells (NK cells) display powerful cytotoxicity to tumour cells and play a pivotal role in tumour therapy. However, the phenotype and functional regulation of NK cells in oesophageal squamous cell carcinoma (ESCC) remains largely unknown.

Methods

Single cell suspensions from blood and tissue samples were isolated by physical dissociation and filtering through a 70 μm cell strainer. Flow cytometry was applied to profile the activity and function of NK cells, and an antibody chip experiment was used to identify and quantitate cytokine levels. We studied IL-6 and IL-8 function in primary oesophageal squamous carcinoma and NK cell co-cultures in vitro and by a xenograft tumour model in vivo. Western blotting was used to quantitate STAT3 (signal transducer and activator of transcription 3) and p-STAT3 levels. Finally, we performed an IHC array to analyse IL-6/IL-8 (interleukin 6/interleukin 8) expression in 103 pairs of tumours and matched adjacent tissues of patients with ESCC to elucidate the correlation between IL-6 or IL-8 and clinical characteristics.

Results

The percentages of NK cells in both peripheral blood and tumour tissues from patients with ESCC were significantly increased in comparison with those in the controls and correlated with the clinical characteristics. Furthermore, the decrease in activating receptors and increase in inhibitory receptors on the surface of tumour-infiltrating NK cells was confirmed by flow cytometry. The level of granzyme B, the effector molecule of tumour-infiltrating NK cells, was also decreased. Mechanistically, primary ESCC cells activated the STAT3 signalling pathway on NK cells through IL-6 and IL-8 secretion, leading to the downregulation of activating receptors (NKp30 and NKG2D) on the surface of NK cells. An ex vivo study showed that blockade of STAT3 attenuated the IL-6/IL-8-mediated impairment of NK cell function. Moreover, the expression of IL-6 or IL-8 in tumour tissues was validated by immunohistochemistry to be positively correlated with tumour progression and poor survival, respectively.

Conclusions

Tumour cell-secreted IL-6 and IL-8 impair the activity and function of NK cells via STAT3 signalling and contribute to oesophageal squamous cell carcinoma malignancy.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1310-0) contains supplementary material, which is available to authorized users.

CAR T cells for brain tumors: Lessons learned and road ahead

Malignant brain tumors, including glioblastoma, represent some of the most difficult to treat of solid tumors. Nevertheless, recent progress in immunotherapy, across a broad range of tumor types, provides hope that immunological approaches will have the potential to improve outcomes for patients with brain tumors. Chimeric antigen receptors (CAR) T cells, a promising immunotherapeutic modality, utilizes the tumor targeting specificity of any antibody or receptor ligand to redirect the cytolytic potency of T cells. The remarkable clinical response rates of CD19-targeted CAR T cells and early clinical experiences in glioblastoma demonstrating safety and evidence for disease modifying activity support the potential of further advancements ultimately providing clinical benefit for patients. The brain, however, is an immune specialized organ presenting unique and specific challenges to immune-based therapies. Remaining barriers to be overcome for achieving effective CAR T cell therapy in the central nervous system (CNS) include tumor antigenic heterogeneity, an immune-suppressive microenvironment, unique properties of the CNS that limit T cell entry, and risks of immune-based toxicities in this highly sensitive organ. This review will summarize preclinical and clinical data for CAR T cell immunotherapy in glioblastoma and other malignant brain tumors, including present obstacles to advancement.

Combining Nanomedicine and Immunotherapy

Nanomedicine holds significant potential to improve the efficacy of cancer immunotherapy. Thus far, nanomedicines, i.e., 1-100(0) nm sized drug delivery systems, have been primarily used to improve the balance between the efficacy and toxicity of conjugated or entrapped chemotherapeutic drugs. The clinical performance of cancer nanomedicines has been somewhat disappointing, which is arguably mostly due to the lack of tools and technologies for patient stratification. Conversely, the clinical progress made with immunotherapy has been spectacular, achieving complete cures and inducing long-term survival in advanced-stage patients. Unfortunately, however, immunotherapy only works well in relatively small subsets of patients. Increasing amounts of preclinical and clinical data demonstrate that combining nanomedicine with immunotherapy can boost therapeutic outcomes, by turning "cold" nonimmunoresponsive tumors and metastases into "hot" immunoresponsive lesions. Nano-immunotherapy can be realized via three different approaches, in which nanomedicines are used (1) to target cancer cells, (2) to target the tumor immune microenvironment, and (3) to target the peripheral immune system. When targeting cancer cells, nanomedicines typically aim to induce immunogenic cell death, thereby triggering the release of tumor antigens and danger-associated molecular patterns, such as calreticulin translocation, high mobility group box 1 protein and adenosine triphosphate. The latter serve as adjuvants to alert antigen-presenting cells to take up, process and present the former, thereby promoting the generation of CD8⁺ cytotoxic T cells. Nanomedicines targeting the tumor immune microenvironment potentiate cancer immunotherapy by inhibiting immunosuppressive cells, such as M2-like tumor-associated macrophages, as well as by reducing the expression of immunosuppressive molecules, such as transforming growth factor beta. In addition, nanomedicines can be employed to promote the activity of antigen-presenting cells and cytotoxic T cells in the tumor immune microenvironment. Nanomedicines targeting the peripheral immune system aim to enhance antigen presentation and cytotoxic T cell production in secondary lymphoid organs, such as lymph nodes and spleen, as well as to engineer and strengthen peripheral effector immune cell populations, thereby promoting anticancer immunity. While the majority of immunomodulatory nanomedicines are in preclinical development, exciting results have already been reported in initial clinical trials. To ensure efficient translation of nano-immunotherapy constructs and concepts, we have to consider biomarkers in their clinical development, to make sure that the right nanomedicine formulation is combined with the right immunotherapy in the right patient. In this context, we have to learn from currently ongoing efforts in nano-biomarker identification as well as from partially already established immuno-biomarker initiatives, such as the Immunoscore and the cancer immunogram. Together, these protocols will help to capture the nano-immuno status in individual patients, enabling the identification and use of individualized and improved nanomedicine-based treatments to boost the performance of cancer immunotherapy.

Harnessing the layer-by-layer assembly technique to design biomaterials vaccines for immune modulation in translational applications

The existence of challenging diseases such as cancers, HIV and Zika requires developing new vaccines that can generate tunable and robust immune responses against the diseases. Biomaterials-based techniques have been broadly explored for designing vaccines that can produce controllable and potent immunity. Among the existing biomaterials-based strategies, the layer-by-layer (LbL) assembly technique is remarkably attractive in vaccine design due to its unique features such as programmed and versatile cargo loading, cargo protection, co-delivery, juxtaposing of immune signals, etc. In this work, we reviewed the existing LbL-based vaccine design techniques for translational applications. Specifically, we discussed nanovaccines constructed by coating polyelectrolyte multilayers (PEMs) on nanoparticles, microcapsule vaccines assembled from PEMs, polyplex/complex vaccines condensed from charged materials and microneedle vaccines deposited with PEMs, highlighting the employment of these techniques to promote immunity against diseases ranging from cancers to infectious and autoimmune diseases (i.e., HIV, influenza, multiple sclerosis, etc.). Additionally, the review specifically emphasized using LbL-based vaccine technologies for tuning the cellular and molecular pathways, demonstrating the unique advantages presented by these vaccination strategies. These studies showed the versatility and potency of using LbL-based techniques for designing the next generation of biomaterials vaccines for translational purposes.

Bioinspired and Biomimetic Nanomedicines

Nanomedicine development aims to enhance the efficacy, accuracy, safety, and/or compliance of diagnosis and treatment of diseases by leveraging the unique properties of engineered nanomaterials. To this end, a multitude of organic and inorganic nanoparticles have been designed to facilitate drug delivery, sensing, and imaging, some of which are currently in clinical trials or have been approved by the Food and Drug Administration (FDA). In the process, the increasing knowledge in understanding how natural particulates, including cells, pathogens, and organelles, interact with body and cellular systems has spurred efforts to mimic their morphology and functions for developing new generations of nanomedicine formulations. In addition, the advances in bioengineering tools, bioconjugation chemistries, and bio-nanotechnologies have further enabled researchers to exploit these natural particulates for theranostic purposes. In this Account, we will discuss the recent progress in our lab on engineering bioinspired and biomimetic synthetic and cellular systems toward rational design of nanomedicine platforms for treating diabetes and cancer. Inspired by the structure and response mechanism of pancreatic β-cells, we synthesized a series of insulin granule-like vesicles that can respond to high blood or intestinal glucose levels for aiding in transdermal or oral insulin delivery, respectively. Then, to more closely mimic the multicompartmental architecture of β-cells, we further developed synthetic artificial cells with vesicle-in-vesicle superstructures which can sense blood glucose levels and dynamically release insulin via a membrane fusion process. Meanwhile, clues drawn from the traits of anaerobic bacteria that selectively invade and proliferate in solid tumors inspired the synthesis of a light-tuned hypoxia-responsive nanovesicle for implementing synergistic cancer therapy. In parallel, we also studied how autologous particulates could be recruited for developing advanced drug delivery systems. Through combination of genetic engineering and top-down cell engineering technologies, biomimetic nanomedicines derived from cytoplasmic membrane with programmed death 1 (PD-1) receptors expressed on surfaces were generated and employed for cancer immunotherapy. Based on our earlier study where aPD-L1 (antibodies against PD ligand 1)-conjugated platelets could release aPD-L1-bearing particles in situ and inhibit postsurgical tumor recurrence, we further genetically engineered megakaryocytes, the precursor cells of platelets, to express PD-1 receptors. In this way, platelets born with checkpoint blocking activity could be produced directly in vitro, avoiding post chemical modification processes while exerting similar therapeutic impact. As a further extension, by virtue of the bone marrow-homing ability of hematopoietic stem cells (HSCs), we recently conceived a cell-combination strategy by conjugating HSCs with platelets decorated with antibodies against PD1 (aPD-1) to suppress the growth and recurrence of leukemia. While we are still on the way of digging deep to understand and optimize bioinspired and biomimetic drug carriers, we expect that the strategies summarized in this Account would contribute to the development of advanced nanomedicines.

Porphyrin-Based Nanomedicines for Cancer Treatment

As unique molecules with both therapeutic and diagnostic properties, porphyrin derivatives have been extensively employed for cancer treatment. Porphyrins not only show powerful phototherapeutic effects (photodynamic and photothermal therapies), but also exhibit excellent imaging capacities, such as near-infrared fluorescent imaging (NIRFI), magnetic resonance imaging (MRI), photoacoustic imaging (PAI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT). In order to take advantage of their robust phototherapeutic effects and excellent imaging capacities, porphyrins can be used to create nanomedicines with effective therapeutic and precise diagnostic properties for cancer treatment. In this Review, we summarize porphyrin-based nanomedicines which have been developed recently, including porphyrin-based liposomes, micelles, polymeric nanoparticles, peptide nanoparticles, and small-molecule nanoassemblies, and their applications on cancer therapy and diagnosis. The outlook and limitation of porphyrin-based nanomedicines are also reviewed.

Biomaterial-Based Activation and Expansion of Tumor-Specific T Cells

Traditional tumor vaccination approaches mostly focus on activating dendritic cells (DCs) by providing them with a source of tumor antigens and/or adjuvants, which in turn activate tumor-reactive T cells. Novel biomaterial-based cancer immunotherapeutic strategies focus on directly activating and stimulating T cells through molecular cues presented on synthetic constructs with the aim of improving T cell survival, more precisely steer T cell activation and direct T cell differentiation. Synthetic artificial antigen presenting cells (aAPCs) decorated with T cell-activating ligands are being developed to induce robust tumor-specific T cell responses, essentially bypassing DCs. In this perspective, we approach these promising new technologies from an immunological angle, first by identifying the CD4⁺ and CD8⁺ T cell subtypes that are imperative for robust anti-cancer immunity and subsequently discussing the molecular cues needed to induce these cells types. We will elaborate on how biomaterials can be applied to stimulate T cells in vitro and in vivo to improve their survival, activation and function. Scaffold-based methods can also be used as delivery vehicles for adoptive transfer of T cells, including tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor expressing (CAR) T cells, while simultaneously stimulating these cells. Finally, we provide suggestions on how these insights could advance the field of biomaterial-based activation and expansion of tumor-specific T cells in the future.

Clickable Methyltetrazine-Indocarbocyanine Lipids: A Multicolor Tool Kit for Efficient Modifications of Cell Membranes

Cell-based therapeutics are one of the most promising and exciting breakthroughs in modern medicine. Modification of the cell surface with ligands, biologics, drugs, and nanoparticles can further enhance the functionality. Previously, we described the synthesis of a dioctadecyl indocarbocyanine Cy3 analog (aminomethyl-DiI) for efficient and stable modification (painting) of mouse erythrocytes with small molecules, enzymes, and biologics. Here, we synthesized a near-infrared aminomethyl dioctadecyl derivative of Cy7 (aminomethyl-DOCy7) and systematically compared it to aminomethyl-DiI as an anchor for the modification of human erythrocytes, Jurkat cells, and primary T cells with immunoglobulin G. To enable copper-free click chemistry modification of cell membranes, we conjugated a methyltetrazine (MTz) group to the amino-indocyanine lipids via a polyethylene glycol (PEG) linker. DOCy7-PEG3400-MTz showed over 99% modification efficiency of human red blood cells (RBCs) at 25 μM. Reaction of trans-cyclooctene (TCO) modified immunoglobulin G (IgG) with DOCy7-PEG₄-MTz-modified RBCs (2-step method) resulted in ∼80,000 IgG molecules per erythrocyte, whereas modification with a preconjugated DOCy7-PEG3400-IgG construct (1-step method) resulted in ∼20,000 IgG molecules per erythrocyte as detected by immuno dot-blot. The number of IgG/RBC was controlled by the concentration of IgG. The incubation of RBCs with DiI-PEG3400-MTz resulted in a similar number of IgG/RBC. Modification of the T-lymphocyte cell line Jurkat with IgG resulted in ∼1 × 10⁶ IgG/cell with the 1-step and 2-step methods, and the efficiency was similar for DOCy7 and DiI constructs. Finally, we used DOCy7 and DiI constructs to demonstrate efficient modification of primary CD3+T cells from healthy donors. In conclusion, click indocarbocyanine conjugates represent a novel multicolor chemical biology tool kit for efficient surface modification of different cells types and can be used for potential imaging and drug delivery applications involving engineered cells.

Combined Antitumor Effects of Sorafenib and GPC3-CAR T Cells in Mouse Models of Hepatocellular Carcinoma

Our previous study indicated that GPC3-targeted chimeric antigen receptor (CAR) T cell therapy has a high safety profile in patients with hepatocellular carcinoma (HCC). However, the response rate requires further improvement. Here, we analyzed the combined effect of GPC3-CAR T cells and sorafenib in both immunocompetent and immunodeficient mouse models of hepatocellular carcinoma. In immunocompetent mouse model, mouse CAR (mCAR) T cells induced regression of small tumors (approximately 130 mm³ tumor volume) but had no effect on large, established tumors (approximately 400 mm³ tumor volume). Sorafenib, at a subpharmacologic but not a pharmacologic dose, augmented the antitumor effects of mCAR T cells, in part by promoting IL12 secretion in tumor-associated macrophages (TAMs) and cancer cell apoptosis. In an immunodeficient mouse model, both subpharmacologic and pharmacologic doses of sorafenib had limited impacts on the function of human CAR (huCAR) T cells in vitro and showed synergistic effects with huCAR T cells in vivo, which can at least partially be ascribed to the upregulated tumor cell apoptosis induced by the combined treatment. Thus, this study applied two of the most commonly used mouse models for CAR T cell research and demonstrated the clinical potential of combining sorafenib with GPC3-targeted CAR T cells against HCC.

Artificially Reprogrammed Macrophages as Tumor-Tropic Immunosuppression-Resistant Biologics to Realize Therapeutics Production and Immune Activation

To engineer patient-derived cells into therapy-purposed biologics is a promising solution to realize personalized treatments. Without using gene-editing technology, a live cell-typed therapeutic is engineered for tumor treatment by artificially reprogramming macrophages with hyaluronic acid-decorated superparamagnetic iron oxide nanoparticles (HIONs). This nanoparticle-assisted cell-reprogramming strategy demonstrates profound advantages, due to the combined contributions from the biological regulation of HIONs and the intrinsic nature of macrophages. Firstly, the reprogrammed macrophages present a substantial improvement in their innate capabilities, such as more effective tumor targeting and more efficient generation of bioactive components (e.g., reactive oxygen species, bioactive cytokines) to suppress tumor growth. Furthermore, this cell therapeutic exhibits cytostatic/proapoptotic effects specific to cancer cells. Secondly, HIONs enable macrophages more resistant to the intratumoral immunosuppressive environment. Thirdly, the macrophages are endowed with a strong ability to prime in situ protumoral M2 macrophages into antitumor M1 phenotype in a paracrine-like manner. Consequently, a synergistic tumor-inhibition effect is achieved. This study shows that engineering nanomaterial-reprogrammed live cells as therapeutic biologics may be a more preferable option to the commonly used approaches where nanomaterials are administrated to induce bioresponse of certain cells in vivo.

Optimizing Advances in Nanoparticle Delivery for Cancer Immunotherapy

Cancer immunotherapy is one of the fastest growing and most promising fields in clinical oncology. T-cell checkpoint inhibitors are revolutionizing the management of advanced cancers including non-small cell lung cancer and melanoma. Unfortunately, many common cancers are not responsive to these drugs and resistance remains problematic. A growing number of novel cancer immunotherapies have been discovered but their clinical translation has been limited by shortcomings of conventional drug delivery. Immune signaling is tightly-regulated and often requires simultaneous or near-simultaneous activation of multiple signals in specific subpopulations of immune cells. Nucleic acid therapies, which require intact intracellular delivery, are among the most promising approaches to modulate the tumor microenvironment to a pro-immunogenic phenotype. Advanced nanomedicines can be precisely engineered to overcome many of these limitations and appear well-poised to enable the clinical translation of promising cancer immunotherapies.

Nanocarrier-based systems for targeted and site specific therapeutic delivery

Systemic drug delivery methods such as oral or parenteral administration of free drugs possess relatively low treatment efficiency and marked adverse side effects. The use of nanoparticles for drug delivery in most cases substantially enhances drug efficacy, improves pharmacokinetics and drug release and limits their side effects. However, further enhancement in drug efficacy and significant limitation of adverse side effects can be achieved by specific targeting of nanocarrier-based delivery systems especially in combination with local administration. The present review describes major advantages and limitations of organic and inorganic nanocarriers or living cell-based drug and nucleic acid delivery systems. Among these, different nanoparticles, supramolecular gels, therapeutic cells as living drug carriers etc. have emerged as a new frontier in modern medicine.

Redox-responsive interleukin-2 nanogel specifically and safely promotes the proliferation and memory precursor differentiation of tumor-reactive T-cells

Interleukin-2 (IL-2) is a potent T-cell mitogen that can adjuvant anti-cancer adoptive T-cell transfer (ACT) immunotherapy by promoting T-cell engraftment. However, the clinical applications of IL-2 in combination with ACT are greatly hindered by the severe adverse effects such as vascular leak syndrome (VLS). Here, we developed a synthetic delivery strategy for IL-2 via backpacking redox-responsive IL-2/Fc nanogels (NGs) to the plasma membrane of adoptively transferred T-cells. The NGs prepared by traceless chemical cross-linking of cytokine proteins selectively released the cargos in response to T-cell receptor activation upon antigen recognition in tumors. We found that IL-2/Fc delivered by T-cell surface-bound NGs expanded transferred tumor-reactive T-cells 80-fold more than the free IL-2/Fc of an equivalent dose administered systemically and showed no effects on tumor-infiltrating regulatory T-cell expansion. Intriguingly, IL-2/Fc NG backpacks that facilitated a sustained and slow release of IL-2/Fc also promoted the CD8+ memory precursor differentiation and induced less T-cell exhaustion in vitro compared to free IL-2/Fc. The controlled responsive delivery of IL-2/Fc enabled the safe administration of repeated doses of the stimulant cytokine with no overt toxicity and improved efficacy against melanoma metastases in a mice model.

Artificial intelligence in nanomedicine

The field of nanomedicine has made substantial strides in the areas of therapeutic and diagnostic development. For example, nanoparticle-modified drug compounds and imaging agents have resulted in markedly enhanced treatment outcomes and contrast efficiency. In recent years, investigational nanomedicine platforms have also been taken into the clinic, with regulatory approval for Abraxane® and other products being awarded. As the nanomedicine field has continued to evolve, multifunctional approaches have been explored to simultaneously integrate therapeutic and diagnostic agents onto a single particle, or deliver multiple nanomedicine-functionalized therapies in unison. Similar to the objectives of conventional combination therapy, these strategies may further improve treatment outcomes through targeted, multi-agent delivery that preserves drug synergy. Also, similar to conventional/unmodified combination therapy, nanomedicine-based drug delivery is often explored at fixed doses. A persistent challenge in all forms of drug administration is that drug synergy is time-dependent, dose-dependent and patient-specific at any given point of treatment. To overcome this challenge, the evolution towards nanomedicine-mediated co-delivery of multiple therapies has made the potential of interfacing artificial intelligence (AI) with nanomedicine to sustain optimization in combinatorial nanotherapy a reality. Specifically, optimizing drug and dose parameters in combinatorial nanomedicine administration is a specific area where AI can actionably realize the full potential of nanomedicine. To this end, this review will examine the role that AI can have in substantially improving nanomedicine-based treatment outcomes, particularly in the context of combination nanotherapy for both N-of-1 and population-optimized treatment.

Genetic Modification Strategies to Enhance CAR T Cell Persistence for Patients With Solid Tumors

Immunotherapy with chimeric antigen receptor (CAR) T cells offers a promising method to improve cure rates and decrease morbidities for patients with cancer. In this regard, CD19-specific CAR T cell therapies have achieved dramatic objective responses for a high percent of patients with CD19-positive leukemia or lymphoma. Most patients with solid tumors however, have experienced transient or no benefit from CAR T cell therapies. Novel strategies are therefore needed to improve CAR T cell function for patients with solid tumors. One obstacle for the field is limited CAR T cell persistence after infusion into patients. In this review we highlight genetic engineering strategies to improve CAR T cell persistence for enhancing antitumor activity for patients with solid tumors.

Recent Progress of Polymeric Nanogels for Gene Delivery

With its nearly unrestricted possibilities, gene therapy attracts more and more significance in modern-day research. The only issue still seeming to hold back its clinical success is the actual effective delivery of genetic material. Nucleic acids are in general challenging to administer to their intracellular targets due to their unfavorable pharmaceutical characteristics. Polymeric nanogels present a promising delivery platform for oligonucleotide-based therapies, as the growing number of reports deliberated in this review represents. Within the scope of this article, recent progress in the employment of nanogels as gene delivery vectors is summarized and different examples of modified, stimuli-responsive, targeted and co-delivering nanogels are discussed in detail. Furthermore, major aspects of successful gene delivery are addressed and critically debated in regards to nanogels, giving insights into what progress has been made and which key issues still need to be further approached.

Recent Advances in Polymeric Nanomedicines for Cancer Immunotherapy

Immunotherapy has emerged as a promising approach to treat cancer, since it facilitates eradication of cancer by enhancing innate and/or adaptive immunity without using cytotoxic drugs. Of the immunotherapeutic approaches, significant clinical potentials are shown in cancer vaccination, immune checkpoint therapy, and adoptive cell transfer. Nevertheless, conventional immunotherapies often involve immune-related adverse effects, such as liver dysfunction, hypophysitis, type I diabetes, and neuropathy. In an attempt to address these issues, polymeric nanomedicines are extensively investigated in recent years. In this review, recent advances in polymeric nanomedicines for cancer immunotherapy are highlighted and thoroughly discussed in terms of 1) antigen presentation, 2) activation of antigen-presenting cells and T cells, and 3) promotion of effector cells. Also, the future perspectives to develop ideal nanomedicines for cancer immunotherapy are provided.

Identifying a Membrane-Type 2 Matrix Metalloproteinase-Targeting Peptide for Human Lung Cancer Detection and Targeting Chemotherapy with Functionalized Mesoporous Silica

Membrane-type 2 matrix metalloproteinase (MT2-MMP) is critical for the aggressive lung tumor growth, progression, and metastasis. Here, to obtain the peptides in binding specifically to MT2-MMP, a phage-displayed 12 peptide library was used and the affinity of peptides toward MT2-MMP was identified by multitest methods. The results showed that a specific MT2-MMP-targeting peptide with the sequence of HHRLHSAPPPQA (MT2-AF5p) exhibited a high specificity and strong affinity against lung tumors. To further achieve specific targeting and precise therapeutic effects, MT2-AF5p was conjugated onto fluorescent mesoporous silica nanoparticles (FMSN-NH₂) and loaded with doxorubicin (DOX) to construct a chemotherapeutic drug-targeting delivery system (DOX-loaded FMSN@MT2-AF5p). The DOX-loaded FMSN@MT2-AF5p achieved a boost in DOX release in an acidic environment. Most importantly, FMSN@MT2-AF5p efficiently targeted the tumor area, as seen in the fluorescent imaging ex vivo. The novel peptide-functionalized nanoparticles with a good biocompatibility are promising for clinical use as a precise targeting nanodrug for lung cancer diagnosis and therapy.

Improving Cancer Vaccine Efficiency by Nanomedicine

Cancer vaccines, which have been widely investigated in the past few decades, are one of the most attractive strategies for cancer immunotherapy. Through the precise delivery of antigens and adjuvants to lymphoid organs or lymphocytes via nanotechnology, innate and adaptive immunity can be boosted to prevent the growth and relapse of malignant tumors. Indeed, nanomedicine offers great opportunities to improve the efficiency of vaccines. Various functional platforms are used to deliver small molecules, peptides, nucleic acids, and even whole cell antigens to the target area of interest, achieving enhanced antitumor immunity and durable therapeutic benefits. Herein, the recent progress in cancer vaccines based on nanotechnology is summarized. Novel platforms used for delivering tumor antigens, promoting adjuvant functions, and combining other therapeutic strategies are discussed. Moreover, possible striving directions and major challenges of nanomedicine for vaccination are also reviewed.

Nanomedicine and macroscale materials in immuno-oncology

Immunotherapy is revolutionizing the treatment of cancer. It can achieve unprecedented responses in advanced-stage patients, including complete cures and long-term survival. However, immunotherapy also has limitations, such as its relatively low response rates and the development of severe side effects. These drawbacks are gradually being overcome by improving our understanding of the immune system, as well as by establishing combination regimens in which immunotherapy is combined with other treatment modalities. In addition to this, in recent years, progress made in chemistry, nanotechnology and materials science has started to impact immuno-oncology, resulting in more effective and less toxic immunotherapy interventions. In this context, multiple different nanomedicine formulations and macroscale materials have been shown to be able to boost anti-cancer immunity and the efficacy of immunomodulatory drugs. We here review nanotechnological and materials chemistry efforts related to endogenous and exogenous vaccination, to the engineering of antigen-presenting cells and T cells, and to the modulation of the tumor microenvironment. We also discuss limitations, current trends and future directions. Together, the insights provided and the evidence obtained indicate that there is a bright future ahead for engineering nanomedicines and macroscale materials for immuno-oncology applications.

Polymeric micro- and nanoparticles for immune modulation

New advances in biomaterial-based approaches to modulate the immune system are being applied to treat cancer, infectious diseases, and autoimmunity. Particulate systems are especially well-suited to deliver immunomodulatory factors to immune cells since their small size allows them to engage cell surface receptors or deliver cargo intracellularly after internalization. Biodegradable polymeric particles are a particularly versatile platform for the delivery of signals to the immune system because they can be easily surface-modified to target specific receptors and engineered to release encapsulated cargo in a precise, sustained manner. Micro- and nanoscale systems have been used to deliver a variety of therapeutic agents including monoclonal antibodies, peptides, and small molecule drugs that function to activate the immune system against cancer or infectious disease, or suppress the immune system to combat autoimmune diseases and transplant rejection. This review provides an overview of recent advances in the development of polymeric micro- and nanoparticulate systems for the presentation and delivery of immunomodulatory agents targeted to a variety of immune cell types including APCs, T cells, B cells, and NK cells.