Multifunctional nanoparticles for cancer immunotherapy

Opportunities and Challenges for Inhalable Nanomedicine Formulations in Respiratory Diseases: A Review

Lungs experience frequent interactions with the external environment and have an abundant supply of blood; therefore, they are susceptible to invasion by pathogenic microorganisms and tumor cells. However, the limited pharmacokinetics of conventional drugs in the lungs poses a clinical challenge. The emergence of different nano-formulations has been facilitated by advancements in nanotechnology. Inhaled nanomedicines exhibit better targeting and prolonged therapeutic effects. Although nano-formulations have great potential, they still present several unknown risks. Herein, we review the (1) physiological anatomy of the lungs and their biological barriers, (2) pharmacokinetics and toxicology of nanomaterial formulations in the lungs; (3) current nanomaterials that can be applied to the respiratory system and related design strategies, and (4) current applications of inhaled nanomaterials in treating respiratory disorders, vaccine design, and imaging detection based on the characteristics of different nanomaterials. Finally, (5) we analyze and summarize the challenges and prospects of nanomaterials for respiratory disease applications. We believe that nanomaterials, particularly inhaled nano-formulations, have excellent prospects for application in respiratory diseases. However, we emphasize that the simultaneous toxic side effects of biological nanomaterials must be considered during the application of these emerging medicines. This study aims to offer comprehensive guidelines and valuable insights for conducting research on nanomaterials in the domain of the respiratory system.

Antibody-conjugated nanoparticles for target-specific drug delivery of chemotherapeutics

Nanotechnology provides effective methods for precisely delivering chemotherapeutics to cancer cells, thereby improving efficacy and reducing off-target side effects. The targeted delivery of nanoscale chemotherapeutics is accomplished by two different approaches, namely the exploitation of leaky tumor vasculature (EPR effect) and the surface modification of nanoparticles (NPs) with various tumor-homing peptides, aptamers, oligonucleotides, and monoclonal antibodies (mAbs). Because of higher binding affinity and specificity, mAbs have received a lot of attention for the detection of selective cancer biomarkers and also for the treatment of various types of cancer. Antibody-conjugated nanoparticles (ACNPs) are an effective targeted therapy for the efficient delivery of chemotherapeutics specifically to the targeted cancer cells. ACNPs combine the benefits of NPs and mAbs to provide high drug loads at the tumor site with better selectivity and delivery efficiency. The mAbs on the NP surfaces recognize their specific receptors expressed on the target cells and release the chemotherapeutic agent in a controlled manner. Appropriately designed and synthesized ACNPs are essential to fully realize their therapeutic benefits. In blood stream, ACNPs instantly interact with biological molecules, and a protein corona is formed. Protein corona formation triggers an immune response and affects the targeting ability of the nanoformulation. In this review, we provide recent findings to highlight several antibody conjugation methods such as adsorption, covalent conjugation, and biotin-avidin interaction. This review also provides an overview of the many effects of the protein corona and the theranostic applications of ACNPs for the treatment of cancer.

Synthesis and Optimization of the Docetaxel-Loaded and Durvalumab-Targeted Human Serum Albumin Nanoparticles, In Vitro Characterization on Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) tends to behave more aggressively compared to other breast cancer subtypes due to the lack of receptors and its limited targeting therapy. In recent years, nanotechnology advancement has led to the development of various nanoparticle platforms for the targeted treatment of cancers. Especially, HSA-NPs have specific advantages such as biocompatibility, adjustable size during production, and relatively easy synthesis. In this study, HSA-NPs were encapsulated with docetaxel (DTX) and functionalized with polyethylene glycol (PEG), also becoming a targeting nanoplatform modified with durvalumab (DVL), and the whole nanostructure was well characterized. Subsequently, drug release studies and various in vitro cell culture studies such as determining the cytotoxicity and apoptotic levels of the nanoplatforms and PD-L1 using ELISA test were conducted on MDA-MB-468, MDA-MB-231, and MCF-7 cells. According to the results, HSA-DTX@PEG-DVL NPs showed better cytotoxicity compared to DTX in all the three cell lines. In addition, it was observed that the HSA-DTX@PEG-DVL NPs did not lead the cells to late apoptosis but were effective in the early apoptotic stage. Moreover, the ELISA data showed a significantly induced PD-L1 expression due to the presence of DVL in the nanostructure, which indicates that DVL antibodies successfully bind to the HSA-DTX@PEG-DVL nanostructure.

The translational paradigm of nanobiomaterials: Biological chemistry to modern applications

Recently nanotechnology has evolved as one of the most revolutionary technologies in the world. It has now become a multi-trillion-dollar business that covers the production of physical, chemical, and biological systems at scales ranging from atomic and molecular levels to a wide range of industrial applications, such as electronics, medicine, and cosmetics. Nanobiomaterials synthesis are promising approaches produced from various biological elements be it plants, bacteria, peptides, nucleic acids, etc. Owing to the better biocompatibility and biological approach of synthesis, they have gained immense attention in the biomedical field. Moreover, due to their scaled-down sized property, nanobiomaterials exhibit remarkable features which make them the potential candidate for different domains of tissue engineering, materials science, pharmacology, biosensors, etc. Miscellaneous characterization techniques have been utilized for the characterization of nanobiomaterials. Currently, the commercial transition of nanotechnology from the research level to the industrial level in the form of nano-scaffolds, implants, and biosensors is stimulating the whole biomedical field starting from bio-mimetic nacres to 3D printing, multiple nanofibers like silk fibers functionalizing as drug delivery systems and in cancer therapy. The contribution of single quantum dot nanoparticles in biological tagging typically in the discipline of genomics and proteomics is noteworthy. This review focuses on the diverse emerging applications of Nanobiomaterials and their mechanistic advancements owing to their physiochemical properties leading to the growth of industries on different biomedical measures. Alongside the implementation of such nanobiomaterials in several drug and gene delivery approaches, optical coding, photodynamic cancer therapy, and vapor sensing have been elaborately discussed in this review. Different parameters based on current challenges and future perspectives are also discussed here.

Delivery of a Cancer-Testis Antigen-Derived Peptide Using Conformationally Restricted Dipeptide-Based Self-Assembled Nanotubes

Use of tumor-associated antigens for cancer immunotherapy is limited due to their poor in vivo stability and low cellular uptake. Delivery of antigenic peptides using synthetic polymer-based nanostructures has been actively pursued but with limited success. Peptide-based nanostructures hold much promise as delivery vehicles due to their easy design and synthesis and inherent biocompatibility. Here, we report self-assembly of a dipeptide containing a non-natural amino acid, α,β-dehydrophenylalanine (ΔF), into nanotubes, which efficiently entrapped a MAGE-3-derived peptide (M3). M3 entrapped in F-ΔF nanotubes was more stable to a nonspecific protease treatment and both F-ΔF and F-ΔF-M3 showed no cellular toxicity for four cancerous and noncancerous cell lines used. F-ΔF-M3 showed significantly higher cellular uptake in RAW 267.4 macrophage cells compared to M3 alone and also induced in vitro maturation of dendritic cells (DCs). Immunization of mice with F-ΔF-M3 selected a higher number of IFN-γ secreting CD8⁺ T cells and CD4⁺ T compared to M3 alone. On day 21, a tumor growth inhibition ratio (TGI, %) of 41% was observed in a murine melanoma model. These results indicate that F-ΔF nanotubes are highly biocompatible, efficiently delivered M3 to generate cytotoxic T lymphocytes responses, and able to protect M3 from degradation under in vivo conditions. The F-ΔF dipeptide-based nanotubes may be considered as a good platform for further development as delivery agents.

Enhancing Cancer Immunotherapy Treatment Goals by Using Nanoparticle Delivery System

Recently, there has been an incredible increase in research about the abnormal growth of cells (neoplasm), focusing on the management, treatment and preventing reoccurrence. It has been understood that the natural defense system, composed of a variety of immune defensive cells, does not just limit its function in eliminating neoplastic cells, but also controls the growth and spread of tumor cells of different kinds to other parts of the body. Cancer immunotherapy, is a cancer treatment plan that educates the body’s defensive system to forestall, control, and eliminate tumor cells. The effectiveness of immunotherapy is achieved, to its highest efficacy, by the use of nanoparticles (NPs) for precise and timely delivery of immunotherapies to specific targeted neoplasms, with less or no harm to the healthy cells. Immunotherapies have been affirmed in clinical trials as a cancer regimen for various types of cancers, the side effects resulting from imprecise and non-targeted conveyance is well managed with the use of nanoparticles. Nonetheless, we will concentrate on enhancing cancer immunotherapy approaches by the use of nanoparticles for the productivity of antitumor immunity. Nanoparticles will be presented and utilized as an objective immunotherapy delivery system for high exactness and are thus a promising methodology for cancer treatment.

Nucleic Acid-Based Approaches for Tumor Therapy

Within the last decade, the introduction of checkpoint inhibitors proposed to boost the patients' anti-tumor immune response has proven the efficacy of immunotherapeutic approaches for tumor therapy. Furthermore, especially in the context of the development of biocompatible, cell type targeting nano-carriers, nucleic acid-based drugs aimed to initiate and to enhance anti-tumor responses have come of age. This review intends to provide a comprehensive overview of the current state of the therapeutic use of nucleic acids for cancer treatment on various levels, comprising (i) mRNA and DNA-based vaccines to be expressed by antigen presenting cells evoking sustained anti-tumor T cell responses, (ii) molecular adjuvants, (iii) strategies to inhibit/reprogram tumor-induced regulatory immune cells e.g., by RNA interference (RNAi), (iv) genetically tailored T cells and natural killer cells to directly recognize tumor antigens, and (v) killing of tumor cells, and reprograming of constituents of the tumor microenvironment by gene transfer and RNAi. Aside from further improvements of individual nucleic acid-based drugs, the major perspective for successful cancer therapy will be combination treatments employing conventional regimens as well as immunotherapeutics like checkpoint inhibitors and nucleic acid-based drugs, each acting on several levels to adequately counter-act tumor immune evasion.

Nanoparticle cancer vaccines: Design considerations and recent advances

Vaccines therapeutics manipulate host's immune system and have broad potential for cancer prevention and treatment. However, due to poor immunogenicity and limited safety, fewer cancer vaccines have been successful in clinical trials. Over the past decades, nanotechnology has been exploited to deliver cancer vaccines, eliciting long-lasting and effective immune responses. Compared to traditional vaccines, cancer vaccines delivered by nanomaterials can be tuned towards desired immune profiles by (1) optimizing the physicochemical properties of the nanomaterial carriers, (2) modifying the nanomaterials with targeting molecules, or (3) co-encapsulating with immunostimulators. In order to develop vaccines with desired immunogenicity, a thorough understanding of parameters that affect immune responses is required. Herein, we discussed the effects of physicochemical properties on antigen presentation and immune response, including but not limited to size, particle rigidity, intrinsic immunogenicity. Furthermore, we provided a detailed overview of recent preclinical and clinical advances in nanotechnology for cancer vaccines, and considerations for future directions in advancing the vaccine platform to widespread anti-cancer applications.

Application of Nanomaterials in Biomedical Imaging and Cancer Therapy

Nanomaterials, such as nanoparticles, nanorods, nanosphere, nanoshells, and nanostars, are very commonly used in biomedical imaging and cancer therapy. They make excellent drug carriers, imaging contrast agents, photothermal agents, photoacoustic agents, and radiation dose enhancers, among other applications. Recent advances in nanotechnology have led to the use of nanomaterials in many areas of functional imaging, cancer therapy, and synergistic combinational platforms. This review will systematically explore various applications of nanomaterials in biomedical imaging and cancer therapy. The medical imaging modalities include magnetic resonance imaging, computed tomography, positron emission tomography, single photon emission computerized tomography, optical imaging, ultrasound, and photoacoustic imaging. Various cancer therapeutic methods will also be included, including photothermal therapy, photodynamic therapy, chemotherapy, and immunotherapy. This review also covers theranostics, which use the same agent in diagnosis and therapy. This includes recent advances in multimodality imaging, image-guided therapy, and combination therapy. We found that the continuous advances of synthesis and design of novel nanomaterials will enhance the future development of medical imaging and cancer therapy. However, more resources should be available to examine side effects and cell toxicity when using nanomaterials in humans.

Emerging Prospects for Nanoparticle-Enabled Cancer Immunotherapy

One of the standards for cancer treatment is cancer immunotherapy which treats both primary and metastasized tumors. Although cancer immunotherapeutics show better outcomes as compared with conventional approaches of cancer treatment, the currently used cancer immunotherapeutics have limited application in delivering cancer antigens to immune cells. Conversely, in solid tumors, tumor microenvironment suppresses the immune system leading to the evasion of anticancer immunity. Some promising attempts have been made to overcome these drawbacks by using different approaches, for instance, the use of biomaterial-based nanoparticles. Accordingly, various studies involving the application of nanoparticles in cancer immunotherapy have been discussed in this review article. This review not only describes the modes of cancer immunotherapy to reveal the importance of nanoparticles in this modality but also narrates nanoparticle-mediated delivery of cancer antigens and therapeutic supplements. Moreover, the impact of nanoparticles on the immunosuppressive behavior of tumor environment has been discussed. The last part of this review deals with cancer immunotherapy using a combination of traditional interventional oncology approach and image-guided local immunotherapy against cancer. According to recent studies, cancer therapy can potentially be improved through nanoparticle-based immunotherapy. In addition, drawbacks associated with the currently used cancer immunotherapeutics can be fixed by using nanoparticles.

Checkpoint Inhibition: Will Combination with Radiotherapy and Nanoparticle-Mediated Delivery Improve Efficacy?

Checkpoint inhibition (CPI) has been a rare success story in the field of cancer immunotherapy. Knowledge gleaned from preclinical studies and patients that do not respond to these therapies suggest that the presence of tumor-infiltrating lymphocytes and establishment of immunostimulatory conditions, prior to CPI treatment, are required for efficacy of CPI. To this end, radiation therapy (RT) has been shown to promote immunogenic cell-death-mediated tumor-antigen release, increase infiltration and cross-priming of T cells, and decreasing immunosuppressive milieu in the tumor microenvironment, hence allowing CPI to take effect. Preclinical and clinical studies evaluating the combination of RT with CPI have been shown to overcome the resistance to either therapy alone. Additionally, nanoparticle and liposome-mediated delivery of checkpoint inhibitors has been shown to overcome toxicities and improve therapeutic efficacy, providing a rationale for clinical investigations of nanoparticle, microparticle, and liposomal delivery of checkpoint inhibitors. In this review, we summarize the preclinical and clinical studies of combined RT and CPI therapies in various cancers, and review findings from studies that evaluated nanoparticle and liposomal delivery of checkpoint inhibitors for cancer treatments.

Self-Assembled, Adjuvant/Antigen-Based Nanovaccine Mediates Anti-Tumor Immune Response against Melanoma Tumor

Malignant melanoma is a highly aggressive type of cancer that requires radical treatment strategies to inhibit the cancer cell progression and metastasis. In recent years, preclinical research and clinical trials on melanoma treatment have been considerably focused on the adjuvant-based immunotherapy for enhancing the immune response of innate immune cells against cancer cells. However, the clinical outcome of these adjuvant-based treatments is inadequate due to an improper delivery system for these immune activators to reach the target site. Hence, we developed a vaccine formulation containing tumor lysate protein (TL) and poly I:C (PIC) complexed with positively charged poly (sorbitol-co-polyethylenimine (PEI) (PSPEI). The resulting ionic PSPEI-polyplexed antigen/adjuvant (PAA) (PSPEI-PAA) nanocomplexes were stable at the physiological condition, are non-toxic, and have enhanced intracellular uptake of antigen and adjuvant in immature dendritic cells leading to dendritic cell maturation. In the murine B16F10 tumor xenograft model, PSPEI-PAA nanocomplexes significantly suppressed tumor growth and did not exhibit any noticeable sign of toxicity. The level of matured dendritic cells (CD80+/CD86+ cells) in the tumor draining lymph node of PSPEI-PAA treated tumor mice were enhanced and therefore CD8+ T cells infiltration in the tumor were enriched. Additionally, the cytotoxic T lymphocytes (CTLs) assay involving co-culturing of splenocytes isolated from the PSPEI-PAA-treated mice with that of B16F10 cells significantly revealed enhanced cancer killing by the TL-reactivated CTLs compared to untreated control mice bearing tumor. Therefore, we strongly believe that PSPEI-PAA nanocomplexes could be an efficient antigen/adjuvant delivery system and enhance the antitumor immune response against melanoma tumor in the future clinical trials.

Toward Personalized Peptide-Based Cancer Nanovaccines: A Facile and Versatile Synthetic Approach

Personalized cancer vaccines (PCVs) are receiving attention as an avenue for cancer immunotherapy. PCVs employ immunogenic peptide epitopes capable of stimulating the immune system to destroy cancer cells with great specificity. Challenges associated with effective delivery of these peptides include poor solubility of hydrophobic sequences, rapid clearance, and poor immunogenicity, among others. The incorporation of peptides into nanoparticles has the potential to overcome these challenges, but the broad range of functionalities found in amino acids presents a challenge to conjugation due to possible interferences and lack of reaction specificity. Herein, a facile and versatile approach to generating nanosized PCVs under mild nonstringent conditions is reported. Following a simple two-step semibatch synthetic approach, amphiphilic hyperbranched polymer-peptide conjugates were prepared by the conjugation of melanoma antigen peptides, either TRP2 (hydrophobic) or MUT30 (hydrophilic), to an alkyne functionalized core via strain-promoted azide-alkyne click chemistry. Self-assembly of the amphiphiles gave spherical nanovaccines (by transmission electron microscopy) with sizes in the range of 10-30 nm (by dynamic light scattering). Fluorescently labeled nanovaccines were prepared to investigate the cellular uptake by antigen presenting cells (dendritic cells), and uptake was confirmed by flow cytometry and microscopy. The TRP2 nanovaccine was taken up the most followed by MUT30 nanoparticles and, finally, nanoparticles without peptide. The nanovaccines showed good biocompatibility against B16-F10 cells, yet the TRP2 peptide showed signs of toxicity, possibly due to its hydrophobicity. A test for immunogenicity revealed that the nanovaccines were poorly immunogenic, implying the need for an adjuvant when administered in vivo. Treatment of mice with melanoma tumors showed that in combination with adjuvant, CpG, groups with the peptide nanovaccines slowed tumor growth and improved survival (up to 24 days, TRP2) compared to the untreated group (14 days).

Nanoparticles: augmenting tumor antigen presentation for vaccine and immunotherapy treatments of cancer

The major goal of immunity is maintaining host survival. Toward this, immune cells recognize and eliminate targets that pose a danger. Primarily, these are external invaders (pathogens) and internal invaders (cancers). Their recognition relies on distinguishing foreign components (antigens) from self-antigens. Since cancer cells are the host's own cells that are harmfully altered, they are difficult to distinguish from normal self. Furthermore, the antigens least resembling the host are often sequestered in parts of the tumor least accessible to immune responses. Therefore, to sufficiently boost immunity, these tumor antigens must be exposed to the immune system. Toward this, nanoparticles provide an innovating means of tumor antigen presentation and are destined to become an integral part of cancer immunotherapy.

Artificial human antigen-presenting cells are superior to dendritic cells at inducing cytotoxic T-cell responses

Peptide recognition through the MHC class I molecule by cytotoxic T lymphocytes (CTLs) leads to the killing of cancer cells. A potential challenge for T-cell immunotherapy is that dendritic cells (DCs) are exposed to the MHC class I-peptide complex for an insufficient amount of time. To improve tumour antigen presentation to T cells and thereby initiate a more effective T-cell response, we generated artificial antigen-presenting cells (aAPCs) by incubating human immature DCs (imDCs) with poly(lactic-co-glycolic) acid nanoparticles (PLGA-NPs) encapsulating tumour antigenic peptides, followed by maturation with lipopolysaccharide. Tumour antigen-specific CTLs were then induced using either peptide-loaded mature DCs (mDCs) or aAPCs, and their activities were analysed using both ELISpot and cytotoxicity assays. We found that the aAPCs induced significantly stronger tumour antigen-specific CTL responses than the controls, which included both mDCs and aAPCs loaded with empty nanoparticles. Moreover, frozen CTLs that were generated by exposure to aAPCs retained the capability to eradicate HLA-A2-positive tumour antigen-bearing cancer cells. These results indicated that aAPCs are superior to DCs when inducing the CTL response because the former are capable of continuously presenting tumour antigens to T cells in a sustained manner. The development of aAPCs with PLGA-NPs encapsulating tumour antigenic peptides is a promising approach for the generation of effective CTL responses in vitro and warrants further assessments in clinical trials.

Nanoparticle Design Strategies for Effective Cancer Immunotherapy

Cancer immunotherapy is a rapidly evolving and paradigm shifting treatment modality that adds a strong tool to the collective cancer treatment arsenal. It can be effective even for late stage diagnoses and has already received clinical approval. Tumors are known to not only avoid immune surveillance but also exploit the immune system to continue local tumor growth and metastasis. Because of this, most immunotherapies, particularly those directed against solid cancers, have thus far only benefited a small minority of patients. Early clinical substantiation lends weight to the claim that cancer immunotherapies, which are adaptive and enduring treatment methods, generate much more sustained and robust anticancer effects when they are effectively formulated in nanoparticles or scaffolds than when they are administered as free drugs. Engineering cancer immunotherapies using nanomaterials is, therefore, a very promising area worthy of further consideration and investigation. This review focuses on the recent advances in cancer immunoengineering using nanoparticles for enhancing the therapeutic efficacy of a diverse range of immunotherapies. The delivery of immunostimulatory agents to antitumor immune cells, such as dendritic or antigen presenting cells, may be a far more efficient tactic to eradicate tumors than delivery of conventional chemotherapeutic and cytotoxic drugs to cancer cells. In addition to its immense therapeutic potential, immunoengineering using nanoparticles also provides a valuable tool for unearthing and understanding the basics of tumor biology. Recent research using nanoparticles for cancer immunotherapy has demonstrated the advantage of physicochemical manipulation in improving the delivery of immunostimulatory agents. In vivo studies have tested a range of particle sizes, mostly less than 300 nm, and particles with both positive and negative zeta potentials for various applications. Material composition and surface modifications have been shown to contribute significantly in selective targeting, efficient delivery and active stimulation of immune system targets. Thus, these investigations, including a wide array of nanoparticles for cancer immunotherapy, substantiate the employment of nanocarriers for efficacious cancer immunotherapies.