Photodynamic Therapy Mediated by Nontoxic Core-Shell Nanoparticles Synergizes with Immune Checkpoint Blockade To Elicit Antitumor Immunity and Antimetastatic Effect on Breast Cancer

P-glycoprotein targeted and near-infrared light-guided depletion of chemoresistant tumors

Drug resistance remains a formidable challenge to cancer therapy. P-glycoprotein (Pgp) contributes to multidrug resistance in numerous cancers by preventing accumulation of anticancer drugs in cancer cells. Strategies to overcome this resistance have been vigorously sought for over 3 decades, yet clinical solutions do not exist. The main reason for the failure is lack of cancer specificity of small-molecule Pgp inhibitors, thus causing severe toxicity in normal tissues. In this study, Pgp-targeted photodynamic therapy (PDT) was developed to achieve superior cancer specificity through antibody targeting plus locoregional light activation. Thus, a Pgp monoclonal antibody was chemically modified with IR700, a porphyrin photosensitizer. In vitro studies showed that the antibody-photosensitizer conjugates specifically bind to Pgp-expressing drug resistant cancer cells, and caused dramatic cytotoxicity upon irradiation with a near infrared light. We then tested our Pgp-targeted approach in mouse xenograft models of chemoresistant ovarian cancer and head and neck cancer. In both models, targeted PDT produced rapid tumor shrinkage, and significantly prolonged survival of tumor-bearing mice. We conclude that our targeted PDT approach produces molecularly targeted and spatially selective ablation of chemoresistant tumors, and thereby provides an effective approach to overcome Pgp-mediated multidrug resistance in cancer, where conventional approaches have failed.

Recent Progress in Metal-Based Nanoparticles Mediated Photodynamic Therapy

Photodynamic therapy (PDT) is able to non-invasively treat and diagnose various cancers and nonmalignant diseases by combining light, oxygen, and photosensitizers (PSs). However, the application of PDT is hindered by poor water solubility and limited light-penetration depth of the currently available photosensitizers (PSs). Water solubility of PSs is crucial for designing pharmaceutical formulation and administration routes. Wavelength of light source at visible range normally has therapeutic depth less than 1 mm. In this review, focus is on the recent research progress of metal-based nanoparticles being applied in PDT. The potential toxicity of these nanoscales and future directions are further discussed.

Metallic Nanoparticles for Cancer Immunotherapy

Cancer immunotherapy, or the utilization of the body's immune system to attack tumor cells, has gained prominence over the past few decades as a viable cancer treatment strategy. Recently approved immunotherapeutics have conferred remission upon patients with previously bleak outcomes and have expanded the number of tools available to treat cancer. Nanoparticles -including polymeric, liposomal, and metallic formulations - naturally traffic to the spleen and lymph organs and the relevant immune cells therein, making them good candidates for delivery of immunotherapeutic agents. Metallic nanoparticle formulations in particular are advantageous because of their potential for dense surface functionalization and their capability for optical or heat based therapeutic methods. Many research groups have investigated the potential of nanoparticle-mediated delivery platforms to improve the efficacy of immunotherapies. Despite the significant preclinical successes demonstrated by many of these platforms over the last twenty years, few metallic nanoparticles have successfully entered clinical trials with none achieving FDA approval for cancer therapy. In this review, we will discuss preclinical research and clinical trials involving metallic nanoparticles (MNPs) for cancer immunotherapy applications and discuss the potential for clinical translation of MNPs.

Photothermal-Activatable Fe3O4 Superparticle Nanodrug Carriers with PD-L1 Immune Checkpoint Blockade for Anti-metastatic Cancer Immunotherapy

Checkpoint blockade immunotherapy has shown great potential in clinical cancer therapy, but the body's systemic immune must be fully activated and generates a positive tumor-specific immune cell response. In this work, we demonstrate the design of the immune-adjuvant nanodrug carriers on the basis of poly(ethylene glycol)- block-poly(lactic- co-glycolic acid) copolymer-encapsulated Fe₃O₄ superparticles (SPs), in which imiquimod (R837), a kind of Toll-like receptor 7 agonist, is loaded. The nanodrug carriers are defined as Fe₃O₄-R837 SPs. The multitasking Fe₃O₄-R837 SPs can destroy the 4T1 breast tumor by photothermal therapy (PTT) under near-infrared laser irradiation to generate the tumor-associated antigens because of the high efficiency of tumor magnetic attraction ability and photothermal effect. The PTT also triggers the release of R837 as the adjuvant to trigger a strong antitumor immune response. By further combining with the checkpoint blockade adjusted by programmed death ligand 1 (PD-L1) antibody, the Fe₃O₄-R837 SP-involved PTT cannot only eliminate the primary tumors but also prevent tumor metastasis to lungs/liver. Meanwhile, this synergistic therapy also shows abscopal effects by completely inhibiting the growth of untreated distant tumors through effectively triggering the tumors infiltrated by CD45⁺ leukocytes. Such findings suggest that Fe₃O₄-R837 SP-involved PTT can significantly potentiate the systemic therapeutic efficiency of PD-L1 checkpoint blockade therapy by activating both innate and adaptive immune systems in the body.

Modulating T-cell-based cancer immunotherapy via particulate systems

Immunotherapy holds tremendous promise for improving cancer treatment in which an appropriate stimulator may naturally trigger the immune system to control cancer. Up-to-date, adoptive T-cell therapy has received two new FDA approvals that provide great hope for some cancer patient groups. Nevertheless, expense and safety-related issues require further study to obtain insight into targets for efficient immunotherapy. The development of material science was largely responsible for providing a promising horizon to strengthen immunoengineering. In this review, we focus on T-cell characteristics in the context of the immune system against cancer and discuss several approaches of exploiting engineered particles to manipulate the responses of T cells and the tumour microenvironment.

Tumor targeting via EPR: Strategies to enhance patient responses

The tumor accumulation of nanomedicines relies on the enhanced permeability and retention (EPR) effect. In the last 5-10 years, it has been increasingly recognized that there is a large inter- and intra-individual heterogeneity in EPR-mediated tumor targeting, explaining the heterogeneous outcomes of clinical trials in which nanomedicine formulations have been evaluated. To address this heterogeneity, as in other areas of oncology drug development, we have to move away from a one-size-fits-all tumor targeting approach, towards methods that can be employed to individualize and improve nanomedicine treatments. To this end, efforts have to be invested in better understanding the nature, the complexity and the heterogeneity of the EPR effect, and in establishing systems and strategies to enhance, combine, bypass and image EPR-based tumor targeting. In the present manuscript, we summarize key studies in which these strategies are explored, and we discuss how these approaches can be employed to enhance patient responses.

Imparting Designer Biorecognition Functionality to Metal-Organic Frameworks by a DNA-Mediated Surface Engineering Strategy

Surface functionality is an essential component for processing and application of metal-organic frameworks (MOFs). A simple and cost-effective strategy for DNA-mediated surface engineering of zirconium-based nanoscale MOFs (NMOFs) is presented, capable of endowing them with specific molecular recognition properties and thus expanding their potential for applications in nanotechnology and biotechnology. It is shown that efficient immobilization of functional DNA on NMOFs can be achieved via surface coordination chemistry. With this strategy, it is demonstrated that such porphyrin-based NMOFs can be modified with a DNA aptamer for targeting specific cancer cells. Furthermore, the DNA-NMOFs can facilitate the delivery of therapeutic DNA (e.g., CpG) into cells for efficient recognition of endosomal Toll-like receptor 9 and subsequent enhanced immunostimulatory activity in vitro and in vivo. No apparent toxicity is observed with systemic delivery of the DNA-NMOFs in vivo. Overall, these results suggest that the strategy allows for surface functionalization of MOFs with different functional DNAs, extending the use of these materials to diverse applications in biosensor, bioimaging, and nanomedicine.

Enhanced Immunotherapy Based on Photodynamic Therapy for Both Primary and Lung Metastasis Tumor Eradication

Metastasis and recurrence are two unavoidable and intractable problems in cancer therapy, despite various robust therapeutic approaches. Currently, it seems that immunotherapy is an effective approach to solve these problems, but the high heterogeneity of tumor tissue, inefficient presentation of tumor antigen, and deficient targeting ability of therapy usually blunt the efficacy of immunotherapy and hinder its clinical application. Herein, an approach based on combining photodynamic and immunological therapy was designed and developed. We synthesized a chimeric peptide, PpIX-1MT, which integrates photosensitizer PpIX with immune checkpoint inhibitor 1MT via a caspase-responsive peptide sequence, Asp-Glu-Val-Asp (DEVD), to realize a cascaded synergistic effect. The PpIX-1MT peptide could form nanoparticles in PBS and accumulate in tumor areas via the enhanced penetration retention effect. Upon 630 nm light irradiation, the PpIX-1MT nanoparticles produced reactive oxygen species, induced apoptosis of cancer cells, and thus facilitated the expression of caspase-3 and the production of tumor antigens, which could trigger an intense immune response. The subsequently released 1MT upon caspase-3 cleavage could further strengthen the immune system and help to activate CD8⁺ T cells effectively. This cascaded synergistic effect could inhibit both primary and lung metastasis tumor effectively, which may provide the solution for solving tumor recurrence and metastasis clinically.

Dual Chemodrug-Loaded Single-Walled Carbon Nanohorns for Multimodal Imaging-Guided Chemo-Photothermal Therapy of Tumors and Lung Metastases

Tumor combination therapy using nano formulations with multimodal synergistic therapeutic effects shows great potential for complete ablation of tumors. However, targeting tumor metastases with nano structures is a major obstacle for therapy. Therefore, developing a combination therapy system able to target both primary tumors and their metastases at distant sites with synergistic therapy is desirable for the complete eradication of tumors. To this end, a dual chemodrug-loaded theranostic system based on single walled carbon nanohorns (SWNHs) is developed for targeting both primary breast tumors and their lung metastases.

Methods: SWNHs were first modified simultaneously with poly (maleic anhydride-alt-1-octadecene) (C₁₈PMH) and methoxypolyethyleneglycol-b-poly-D, L-lactide (mPEG-PLA) via hydrophobic-hydrophobic interactions and π-π stacking. Then cisplatin and doxorubicin (DOX) (2.9:1 molar ratio) were sequentially loaded onto the modified nanohorns in a noninterfering way. After careful examinations of the release profiles of the loaded drugs and the photothermal performance of the dual chemodrug-loaded SWNHs, termed SWNHs/C₁₈PMH/mPEG-PLA-DOX-Pt, the dual drug chemotherapeutic and chemo-photothermal synergetic therapeutic effects on tumor cells were evaluated. Subsequently, the in vivo behavior and tumor accumulation of the drug-loaded SWNHs were studied by photoacoustic imaging (PAI). For chemo-photothermal therapy of tumors, 4T1 tumor bearing mice were intravenously injected with SWNHs/C₁₈PMH/mPEG-PLA-DOX-Pt at a dose of 10 mg/kg b.w. (in SWNHs) and tumors were illuminated by an 808 nm laser (1W/cm² for 5 min) 24 h post-injection.

Results: DOX and cisplatin were loaded onto the modified SWNHs with high efficiency (44 wt% and 66 wt%, respectively) and released in a pH-sensitive, tandem and sustainable manner. The SWNHs/C₁₈PMH/mPEG-PLA-DOX-Pt had a hydrodynamic diameter of 182 ± 3.2 nm, were highly stable in physiological environment, and had both dual drug chemotherapeutic (CI = 0.439) and chemo-photothermal synergistic antitumor effects (CI = 0.396) in vitro. Moreover, the dual drug-loaded SWNHs had a long blood half-life (10.9 h) and could address both the primary breast tumors and their lung metastases after intravenous administration. Consequently, chemo-photothermal combination therapy ablated the primary tumors and simultaneously eradicated the metastatic lung nodules.

Conclusion: Our study demonstrates that SWNHs/C₁₈PMH/mPEG-PLA-DOX-Pt is highly potent for chemo-photothermal combination therapy of primary tumors and cocktail chemotherapy of their metastases at a distant site.

Nanotechnology Strategies To Advance Outcomes in Clinical Cancer Care

Ongoing research into the application of nanotechnology for cancer treatment and diagnosis has demonstrated its advantages within contemporary oncology as well as its intrinsic limitations. The National Cancer Institute publishes the Cancer Nanotechnology Plan every 5 years since 2005. The most recent iteration helped codify the ongoing basic and translational efforts of the field and displayed its breadth with several evolving areas. From merely a technological perspective, this field has seen tremendous growth and success. However, an incomplete understanding of human cancer biology persists relative to the application of nanoscale materials within contemporary oncology. As such, this review presents several evolving areas in cancer nanotechnology in order to identify key clinical and biological challenges that need to be addressed to improve patient outcomes. From this clinical perspective, a sampling of the nano-enabled solutions attempting to overcome barriers faced by traditional therapeutics and diagnostics in the clinical setting are discussed. Finally, a strategic outlook of the future is discussed to highlight the need for next-generation cancer nanotechnology tools designed to address critical gaps in clinical cancer care.

Immunoengineering with biomaterials for enhanced cancer immunotherapy

Cancer immunotherapy has recently shown dramatic clinical success inducing durable response in patients of a wide variety of malignancies. Further improvement of the clinical outcome with immune related cancer treatment requests more exquisite manipulation of a patient's immune system with increased immunity against diseases while mitigating the toxicities. To meet this challenge, biomaterials applied to immunoengineering are being developed to achieve tissue- and/or cell-specific immunomodulation and thus could potentially enhance both the efficacy and safety of current cancer immunotherapies. Here, we review the recent advancement in the field of immunoengineering using biomaterials and their applications in promoting different modalities of cancer immunotherapies, with focus on cell-, antibody-, immunomodulator-, and gene-based immune related treatments and their combinations with conventional therapies. Challenges and opportunities are discussed in applying biomaterials engineering strategies in the development of future cancer immunotherapies. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

Advanced smart-photosensitizers for more effective cancer treatment

Photodynamic therapy (PDT) based upon the use of light and photosensitizers (PSs) has been used as a novel treatment approach for a variety of tumors. It, however, has several major limitations in the clinic: poor water solubility, long-term phototoxicity, low tumor targeting efficacy, and limited light penetration. With advances in nanotechnology, materials science, and clinical interventional imaging procedures, various smart-PSs have been developed for improving their cancer-therapeutic efficacy while reducing the adverse effects. Here, we briefly review state-of-the-art smart-PSs and discuss the future directions of PDT technology.

Enhancing cancer immunotherapy through nanotechnology-mediated tumor infiltration and activation of immune cells

Cancer immunotherapy has become arguably the most promising advancement in cancer research and therapy in recent years. The efficacy of cancer immunotherapy is critically dependent on specific physiological and physical processes - collectively referred to as transport barriers - including the activation of T cells by antigen presenting cells, T cells migration to and penetration into the tumor microenvironment, and movement of nutrients and other immune cells through the tumor microenvironment. Nanotechnology-based approaches have great potential to help overcome these transport barriers. In this review, we discuss the ways that nanotechnology is being leveraged to improve the efficacy and potency of various cancer immunotherapies.

A metal-semiconductor nanocomposite as an efficient oxygen-independent photosensitizer for photodynamic tumor therapy

Photodynamic therapy (PDT) is regarded as one of the most promising cancer treatments, and oxygen-independent photosensitizers have been intensively explored for advancing the development of PDT. Here, we reported on a superior hybrid nanocomposite (HNC) consisting of a metal (Au deposition) and a semiconductor (CdSe-seeded/CdS nanorods) as a photosensitizer. Under visible light, the photogenerated holes were three-dimensionally confined to the CdSe quantum dots and the delocalized electrons were transferred to the Au tips, which provided hydrogen and oxygen evolution sites for water splitting to generate reactive oxygen species (ROS) with no need for oxygen participation. Compared with semiconductors without deposited metal (i.e. raw CdSe-seeded/CdS nanorods (NRs)) under a normoxic or hypoxic environment, the HNCs exhibited substantially enhanced light-triggered ROS generation in vitro. After being modified with an Arg-Gly-Asp (RGD) peptide sequence, the nanocomposite was deemed as a tumor-targeting, long-lived and oxygen-independent photosensitizer with promoted PDT efficiency for in vivo anti-tumor therapy. This oxygen-independent nanocomposite successfully overcame the hypoxia-related PDT resistance by water splitting, which opened a window to develop conventional semiconductors as photosensitizers for effective PDT.

Inhibiting Metastasis and Preventing Tumor Relapse by Triggering Host Immunity with Tumor-Targeted Photodynamic Therapy Using Photosensitizer-Loaded Functional Nanographenes

Effective cancer therapy depends not only on destroying the primary tumor but also on conditioning the host immune system to recognize and eliminate residual tumor cells and prevent metastasis. In this study, a tumor integrin αvβ6-targeting peptide (the HK peptide)-functionalized graphene oxide (GO) was coated with a photosensitizer (HPPH). The resulting GO conjugate, GO(HPPH)-PEG-HK, was investigated whether it could destroy primary tumors and boost host antitumor immunity. We found that GO(HPPH)-PEG-HK exhibited significantly higher tumor uptake than GO(HPPH)-PEG and HPPH. Photodynamic therapy (PDT) using GO(HPPH)-PEG suppressed tumor growth in both subcutaneous and lung metastatic mouse models. Necrotic tumor cells caused by GO(HPPH)-PEG-HK PDT activated dendritic cells and significantly prevented tumor growth and lung metastasis by increasing the infiltration of cytotoxic CD8⁺ T lymphocytes within tumors as evidenced by in vivo optical and single-photon emission computed tomography (SPECT)/CT imaging. These results demonstrate that tumor-targeted PDT using GO(HPPH)-PEG-HK could effectively ablate primary tumors and destroy residual tumor cells, thereby preventing distant metastasis by activating host antitumor immunity and suppressing tumor relapse by stimulation of immunological memory.

Nanomaterials for cancer immunotherapy

Cancer immunotherapy is quickly growing to be the fourth most important cancer therapy, after surgery, radiation therapy, and chemotherapy. Immunotherapy is the most promising cancer management strategy because it orchestrates the body's own immune system to target and eradicate cancer cells, which may result in durable antitumor responses and reduce metastasis and recurrence more than traditional treatments. Nanomaterials hold great promise in further improving the efficiency of cancer immunotherapy - in many cases, they are even necessary for effective delivery. In this review, we briefly summarize the basic principles of cancer immunotherapy and explain why and where to apply nanomaterials in cancer immunotherapy, with special emphasis on cancer vaccines and tumor microenvironment modulation.

Injecting nanoparticles into immunotherapy

Sarah Webb explores nanoscience strategies for activating T cells in the fight against cancer.

Metal-Organic Framework (MOF)-Based Drug/Cargo Delivery and Cancer Therapy

Metal-organic frameworks (MOFs)-an emerging class of hybrid porous materials built from metal ions or clusters bridged by organic linkers-have attracted increasing attention in recent years. The superior properties of MOFs, such as well-defined pore aperture, tailorable composition and structure, tunable size, versatile functionality, high agent loading, and improved biocompatibility, make them promising candidates as drug delivery hosts. Furthermore, scientists have made remarkable achievements in the field of nanomedical applications of MOFs, owing to their facile synthesis on the nanoscale and alternative functionalization via inclusion and surface chemistry. A brief introduction to the applications of MOFs in controlled drug/cargo delivery and cancer therapy that have been reported in recent years is provided here.

Highly Emissive Dye-Sensitized Upconversion Nanostructure for Dual-Photosensitizer Photodynamic Therapy and Bioimaging

Rare-earth-based upconversion nanotechnology has recently shown great promise for photodynamic therapy (PDT). However, the NIR-induced PDT is greatly restricted by overheating issues on normal bodies and low yields of reactive oxygen species (ROS, ¹O₂). Here, IR-808-sensitized upconversion nanoparticles (NaGdF₄:Yb,Er@NaGdF₄:Nd,Yb) were combined with mesoporous silica, which has Ce6 (red-light-excited photosensitizer) and MC540 (green-light-excited photosensitizer) loaded inside through covalent bond and electrostatic interaction, respectively. When irradiated by tissue-penetrable 808 nm light, the IR-808 greatly absorb 808 nm photons and then emit a broadband peak which overlaps perfectly with the absorption of Nd³⁺ and Yb³⁺. Thereafter, the Nd³⁺/Yb³⁺ incorporated shell synergistically captures the emitted NIR photons to illuminate NaGdF₄:Yb,Er zone and then radiate ultrabright green and red emissions. The visible emissions simultaneously activate the dual-photosensitizer to produce a large amount of ROS and, importantly, low heating effects. The in vitro and in vivo experiments indicate that the dual-photosensitizer nanostructure has trimodal (UCL/CT/MRI) imaging functions and high anticancer effectiveness, suggesting its potential clinical application as an imaging-guided PDT technique.

GSH-triggered size increase of porphyrin-containing nanosystems for enhanced retention and photodynamic activity

We demonstrate the rational design of a size changeable nanosystem triggered by intracellular GSH for enhanced retention and photodynamic activity.

Breaking the reduced glutathione-activated antioxidant defence for enhanced photodynamic therapy

Photodynamic therapy (PDT) has been applied in cancer treatment by utilizing reactive oxygen species (ROSs) to kill cancer cells.