CpG oligodeoxynucleotide as immune adjuvant enhances photodynamic therapy response in murine metastatic breast cancer

Recent advancements of hydrogels in immunotherapy: Breast cancer treatment

Breast cancer is the most prevalent cancer among women and the leading cause of cancer-related deaths in this population. Recent advances in Immunotherapy, or combined immunotherapy, offering a more targeted and less toxic approach, expand the survival rate of patients more than conventional treatment. Notably, hydrogels, a versatile platform provided promising avenues to combat breast cancer in preclinical studies and extended to clinical practices. With advantages such as the alternation of tumor microenvironment, immunomodulation, targeted delivery of therapeutic agents, and their sustained release at specific sites of interest, hydrogels can potentially be used for the treatment of breast cancer. This review highlights the advantages, mechanisms of action, stimuli-responsiveness properties, and recent advancements of hydrogels for treating breast cancer immunotherapy. Moreover, post-treatment and its clinical translations are discussed in this review. The integration of hydrogels in immunotherapy strategies may pave the way for more effective, personalized, and patient-friendly approaches to combat breast cancer, ultimately contributing to a brighter future for breast cancer patients.

Recent advances in light-triggered cancer immunotherapy

Light-triggered phototherapies, such as photodynamic therapy (PDT) and photothermal therapy (PTT), have shown strong therapeutic efficacy with minimal invasiveness and systemic toxicity, offering opportunities for tumor-specific therapies. Phototherapies not only induce direct tumor cell killing, but also trigger anti-tumor immune responses by releasing various immune-stimulating factors. In recent years, conventional phototherapies have been combined with cancer immunotherapy as synergistic therapeutic modalities to eradicate cancer by exploiting the innate and adaptive immunity. These combined photoimmunotherapies have demonstrated excellent therapeutic efficacy in preventing tumor recurrence and metastasis compared to phototherapy alone. This review covers recent advancements in combined photoimmunotherapy, including photoimmunotherapy (PIT), PDT-combined immunotherapy, and PTT-combined immunotherapy, along with their underlying anti-tumor immune response mechanisms. In addition, the challenges and future research directions for light-triggered cancer immunotherapy are discussed.

Nanoplatform-enhanced photodynamic therapy for the induction of immunogenic cell death

As an efficient, non-invasive, low-side-effect, and highly selective cancer therapy, photodynamic therapy (PDT) is used to treat various malignant tumors. However, the inefficiency of dealing with deep tumors and metastatic lesions highly limits the use of PDT. Immunogenic cell death (ICD) is a particular form of tumor cell death that could elicit a tumor-special immune response, leading to a systemic anti-tumor effect and providing therapeutic benefits for metastatic lesions. In this regard, it is crucial to enhance the ability of PDT to induce ICD. Luckily, advanced nanotechnology created many promising ways to improve the immunogenicity of PDT and achieve photoimmunotherapy. This review summarizes the emerging strategies for triggering immunogenic cell death via nanoplatform-enhanced PDT, with particular emphasis on their advantages in photoimmunotherapy. We highlight the nanoplatforms classified according to the basic principles of photodynamic therapy and immunogenic cell death, which provides a valuable reference for the design of nanoplatform for photoimmunotherapy. In addition, we also discuss the current situation and prospect of nano-based photoimmunotherapy in clinical studies.

Photodynamic Therapy-Induced Anti-Tumor Immunity: Influence Factors and Synergistic Enhancement Strategies

Photodynamic therapy (PDT) is an approved therapeutic procedure that exerts cytotoxic activity towards tumor cells by activating photosensitizers (PSs) with light exposure to produce reactive oxygen species (ROS). Compared to traditional treatment strategies such as surgery, chemotherapy, and radiation therapy, PDT not only kills the primary tumors, but also effectively suppresses metastatic tumors by activating the immune response. However, the anti-tumor immune effects induced by PDT are influenced by several factors, including the localization of PSs in cells, PSs concentration, fluence rate of light, oxygen concentration, and the integrity of immune function. In this review, we systematically summarize the influence factors of anti-tumor immune effects mediated by PDT. Furthermore, an update on the combination of PDT and other immunotherapy strategies are provided. Finally, the future directions and challenges of anti-tumor immunity induced by PDT are discussed.

Combination of verteporfin-photodynamic therapy with 5-aza-2'-deoxycytidine enhances the anti-tumour immune response in triple negative breast cancer

Introduction

Triple negative breast cancer (TNBC) is a subtype of breast cancer characterised by its high tumourigenic, invasive, and immunosuppressive nature. Photodynamic therapy (PDT) is a focal therapy that uses light to activate a photosensitizing agent and induce a cytotoxic effect. 5-aza-2'-deoxycytidine (5-ADC) is a clinically approved immunomodulatory chemotherapy agent. The mechanism of the combination therapy using PDT and 5-ADC in evoking an anti-tumour response is not fully understood.

Methods

The present study examined whether a single dose of 5-ADC enhances the cytotoxic and anti-tumour immune effect of low dose PDT with verteporfin as the photosensitiser in a TNBC orthotopic syngeneic murine model, using the triple negative murine mammary tumour cell line 4T1. Histopathology analysis, digital pathology and immunohistochemistry of treated tumours and distant sites were assessed. Flow cytometry of splenic and breast tissue was used to identify T cell populations. Bioinformatics were used to identify tumour immune microenvironments related to TNBC patients.

Results

Functional experiments showed that PDT was most effective when used in combination with 5-ADC to optimize its efficacy. 5-ADC/PDT combination therapy elicited a synergistic effect in vitro and was significantly more cytotoxic than monotherapies on 4T1 tumour cells. For tumour therapy, all types of treatments demonstrated histopathologically defined margins of necrosis, increased T cell expression in the spleen with absence of metastases or distant tissue destruction. Flow cytometry and digital pathology results showed significant increases in CD8 expressing cells with all treatments, whereas only the 5-ADC/PDT combination therapy showed increase in CD4 expression. Bioinformatics analysis of in silico publicly available TNBC data identified BCL3 and BCL2 as well as the following anti-tumour immune response biomarkers as significantly altered in TNBC compared to other breast cancer subtypes: GZMA, PRF1, CXCL1, CCL2, CCL4, and CCL5. Interestingly, molecular biomarker assays showed increase in anti-tumour response genes after treatment. The results showed concomitant increase in BCL3, with decrease in BCL2 expression in TNBC treatment. In addition, the treatments showed decrease in PRF1, CCL2, CCL4, and CCL5 genes with 5-ADC and 5-ADC/PDT treatment in both spleen and breast tissue, with the latter showing the most decrease.

Discussion

To our knowledge, this is the first study that shows which of the innate and adaptive immune biomarkers are activated during PDT related treatment of the TNBC 4T1 mouse models. The results also indicate that some of the immune response biomarkers can be used to monitor the effectiveness of PDT treatment in TNBC murine model warranting further investigation in human subjects.

Application of Photodynamic Therapy in Pediatric Dentistry: Literature Review

Microbiological control of dental pathologies presents a significant clinical challenge for dental surgeons, particularly considering drug-resistant microorganisms. To address this issue, Antimicrobial Photodynamic Therapy (PDT) has emerged as an effective and complementary technique for microbial reduction. This therapy involves the application of a photosensitizer dye (PS) either topically or systemically, followed by exposure to low-power lasers with appropriate visible light wavelengths. PDT has found a valuable place in dentistry across various specialties, including surgery, periodontics, endodontics, dentistry, implantology, orthodontics, and pediatrics. In the realm of pediatric dentistry, managing microorganisms during dental treatments has become a major challenge. Considering its promising results and ease of application, Photodynamic Therapy presents an interesting alternative for clinical practice. However, it is important to note that specific protocols must be followed for each application, encompassing the type of photosensitizer, concentration, pre-irradiation time, light type, wavelength, energy, power, and mode of light delivery. Researchers have been steadily refining these protocols to facilitate PDT's integration into clinical practice. The objective of this review is to describe in which procedures and oral health problems in children PDT can be applied. In this sense, we list what the literature brings about the possibilities of applying PDT in a pediatric dentistry clinic.

Insight into the Prospects for Tumor Therapy Based on Photodynamic Immunotherapy

Malignancy is one of the common diseases with high mortality worldwide and the most important obstacle to improving the overall life expectancy of the population in the 21st century. Currently, single or combined treatments, including surgery, chemotherapy, and radiotherapy, are still the mainstream regimens for tumor treatment, but they all present significant side effects on normal tissues and organs, such as organ hypofunction, energy metabolism disorders, and various concurrent diseases. Based on this, theranostic measures for the highly selective killing of tumor cells have always been a hot area in cancer-related fields, among which photodynamic therapy (PDT) is expected to be an ideal candidate for practical clinical application due to its precise targeting and excellent safety performance, so-called PDT refers to a therapeutic method mainly composed of photosensitizers (PSs), laser light, and reactive oxygen species (ROS). Photoimmunotherapy (PIT), a combination of PDT and immunotherapy, can induce systemic antitumor immune responses and inhibit continuing growth and distant metastasis of residual tumor cells, demonstrating a promising application prospect. This article reviews the types of immune responses that occur in the host after PDT treatment, including innate and adaptive immunity. To further help PIT-related drugs improve their pharmacokinetic properties and bioavailability, we highlight the potential improvement of photodynamic immunotherapy from three aspects: immunostimulatory agents, tumor-associated antigens (TAAs) as well as different immune cells. Finally, we focus on recent advances in various strategies and shed light on their corresponding mechanisms of immune activation and possible clinical applications such as cancer vaccines. Having discovered the inherent potential of PDT and the mechanisms that PDT triggers host immune responses, a variety of immunotherapeutic strategies have been investigated in parallel with approaches to improve PDT efficiency. However, it remains to be further elucidated under what conditions the immune effect induced by PDT can achieve tumor immunosuppression and to what extent PDT-induced antitumor immunity will lead to complete tumor rejection. Currently, PIT presents several outstanding intractable challenges, such as the aggregation ability of PSs locally in tumors, deep tissue penetration ability of laser light, immune escape, and biological toxicity, and it is hoped that these issues raised will help to point out the direction of preclinical research on PIT and accelerate its transition to clinical practice.

Chondroitin sulfate-based prodrug nanoparticles enhance photodynamic immunotherapy via Golgi apparatus targeting

Photodynamic therapy (PDT) is an emerging therapeutic approach that can inhibit tumor growth by destroying local tumors and activating systemic antitumor immune responses. However, PDT can be ineffective because of photosensitizer aggregation, tumor-induced dendritic cells (DC_S) dysfunction and PDT-mediated immunosuppression. Therefore, we designed chondroitin sulfate-based prodrug nanoparticles for the co-delivery of the photosensitizer chlorin e6 (Ce6) and retinoic acid (RA), which can reduce PDT-mediated immunosuppression by disrupting the Golgi apparatus and blocking the production of immunosuppressive cytokines. Moreover, CpG oligodeoxynucleotide was combined as immunoadjuvant to promote the maturation of DCs. As expected, the strategy of Golgi apparatus targeting immunotherapy combined PDT was confirmed to relieve PDT-induced immunosuppression, showed excellent PDT antitumor efficacy in B16F10-subcutaneous bearing mice model. Thus, our finding offers a promising approach for photodynamic immunotherapy of advanced cancers. STATEMENT OF SIGNIFICANCE: Golgi apparatus has been shown to be a potential target of immunosuppression for producing several immunosuppressive cytokines. In this work, a Golgi apparatus-targeted prodrug nanoparticle was developed to enhance the immune response in photodynamic immunotherapy. The nanoparticle can target and disrupt the Golgi apparatus in tumor cells, which reduced PDT-mediated immunosuppression by blocking the production of immunosuppressive cytokines. This work provides an effective strategy of PDT in combination with the Golgi apparatus-targeted nanovesicle for enhanced cancer therapy.

Photodynamic Therapy-Mediated Immune Responses in Three-Dimensional Tumor Models

Photodynamic therapy (PDT) is a promising non-invasive phototherapeutic approach for cancer therapy that can eliminate local tumor cells and produce systemic antitumor immune responses. In recent years, significant efforts have been made in developing strategies to further investigate the immune mechanisms triggered by PDT. The majority of in vitro experimental models still rely on the two-dimensional (2D) cell cultures that do not mimic a three-dimensional (3D) cellular environment in the human body, such as cellular heterogeneity, nutrient gradient, growth mechanisms, and the interaction between cells as well as the extracellular matrix (ECM) and therapeutic resistance to anticancer treatments. In addition, in vivo animal studies are highly expensive and time consuming, which may also show physiological discrepancies between animals and humans. In this sense, there is growing interest in the utilization of 3D tumor models, since they precisely mimic different features of solid tumors. This review summarizes the characteristics and techniques for 3D tumor model generation. Furthermore, we provide an overview of innate and adaptive immune responses induced by PDT in several in vitro and in vivo tumor models. Future perspectives are highlighted for further enhancing PDT immune responses as well as ideal experimental models for antitumor immune response studies.

Progress in Nanocarriers Codelivery System to Enhance the Anticancer Effect of Photodynamic Therapy

Photodynamic therapy (PDT) is a promising anticancer noninvasive method and has great potential for clinical applications. Unfortunately, PDT still has many limitations, such as metastatic tumor at unknown sites, inadequate light delivery and a lack of sufficient oxygen. Recent studies have demonstrated that photodynamic therapy in combination with other therapies can enhance anticancer effects. The development of new nanomaterials provides a platform for the codelivery of two or more therapeutic drugs, which is a promising cancer treatment method. The use of multifunctional nanocarriers for the codelivery of two or more drugs can improve physical and chemical properties, increase tumor site aggregation, and enhance the antitumor effect through synergistic actions, which is worthy of further study. This review focuses on the latest research progress on the synergistic enhancement of PDT by simultaneous multidrug administration using codelivery nanocarriers. We introduce the design of codelivery nanocarriers and discuss the mechanism of PDT combined with other antitumor methods. The combination of PDT and chemotherapy, gene therapy, immunotherapy, photothermal therapy, hyperthermia, radiotherapy, sonodynamic therapy and even multidrug therapy are discussed to provide a comprehensive understanding.

Progress of Phototherapy Applications in the Treatment of Bone Cancer

Bone cancer including primary bone cancer and metastatic bone cancer, remains a challenge claiming millions of lives and affecting the life quality of survivors. Conventional treatments of bone cancer include wide surgical resection, radiotherapy, and chemotherapy. However, some bone cancer cells may remain or recur in the local area after resection, some are highly resistant to chemotherapy, and some are insensitive to radiotherapy. Phototherapy (PT) including photodynamic therapy (PDT) and photothermal therapy (PTT), is a clinically approved, minimally invasive, and highly selective treatment, and has been widely reported for cancer therapy. Under the irradiation of light of a specific wavelength, the photosensitizer (PS) in PDT can cause the increase of intracellular ROS and the photothermal agent (PTA) in PTT can induce photothermal conversion, leading to the tumoricidal effects. In this review, the progress of PT applications in the treatment of bone cancer has been outlined and summarized, and some envisioned challenges and future perspectives have been mentioned. This review provides the current state of the art regarding PDT and PTT in bone cancer and inspiration for future studies on PT.

Nanomaterials-Based Photodynamic Therapy with Combined Treatment Improves Antitumor Efficacy Through Boosting Immunogenic Cell Death

Benefiting from the rapid development of nanotechnology, photodynamic therapy (PDT) is arising as a novel non-invasive clinical treatment for specific cancers, which exerts direct efficacy in destroying primary tumors by generating excessive cytotoxic reactive oxygen species (ROS). Notably, PDT-induced cell death is related to T cell-mediated antitumor immune responses through induction of immunogenic cell death (ICD). However, ICD elicited via PDT is not strong enough and is limited by immunosuppressive tumor microenvironment (ITM). Therefore, it is necessary to improve PDT efficacy through enhancing ICD with the combination of synergistic tumor therapies. Herein, the recent progress of nanomaterials-based PDT combined with chemotherapy, photothermal therapy, radiotherapy, and immunotherapy, employing ICD-boosted treatments is reviewed. An outlook about the future application in clinics of nanomaterials-based PDT strategies is also mentioned.

Factors Affecting Photodynamic Therapy and Anti-Tumor Immune Response

Photodynamic Therapy (PDT) is a cancer therapy involving the systemic injection of a Photosensitizer (PS) that localizes to some extent in a tumor. After an appropriate time (ranging from minutes to days), the tumor is irradiated with red or near-infrared light either as a surface spot or by interstitial optical fibers. The PS is excited by the light to form a long-lived triplet state that can react with ambient oxygen to produce Reactive Oxygen Species (ROS) such as singlet oxygen and/or hydroxyl radicals, that kill tumor cells, destroy tumor blood vessels, and lead to tumor regression and necrosis. It has long been realized that in some cases, PDT can also stimulate the host immune system, leading to a systemic anti-tumor immune response that can also destroy distant metastases and guard against tumor recurrence. The present paper aims to cover some of the factors that can affect the likelihood and efficiency of this immune response. The structure of the PS, drug-light interval, rate of light delivery, mode of cancer cell death, expression of tumor-associated antigens, and combinations of PDT with various adjuvants all can play a role in stimulating the host immune system. Considering the recent revolution in tumor immunotherapy triggered by the success of checkpoint inhibitors, it appears that the time is ripe for PDT to be investigated in combination with other approaches in clinical scenarios.

Sendai virus-based immunoadjuvant in hydrogel vaccine intensity-modulated dendritic cells activation for suppressing tumorigenesis

The conventional immunoadjuvants in vaccine have weak effect on stimulating antigen presentation and activating anti-tumor immunity. Unexpectedly, we discovered that non-pathogenic Sendai virus (SeV) could activate antigen-presenting cells (APCs) represented by dendritic cells (DCs). Here, we designed an injectable SeV-based hydrogel vaccine (SHV) to execute multi-channel recruitment and stimulation of DCs for boosting the specific immune response against tumors. After the release of the NIR-triggered antigens from tumor cells, dendritic cells around the vaccine efficiently transport the antigens to lymph nodes and present them to T lymphocytes, thereby inducing systemic anti-tumor immune memory. Our findings demonstrated that the SHV with excellent universality, convenience and flexibility has achieved better immune protection effects in inhibiting the occurrence of melanoma and breast cancer. In conclusion, the SHV system might serve as the next generation of personalized anti-tumor vaccines with enhanced features over standard vaccination regimens, and represented an alternative way to suppress tumorigenesis.

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SeV served as immuneadjuvant can activate APCs through TLR7/8 and TLR3 pathways.

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Non-pathogenic SeV in the injectable hydrogel vaccine recruit and activate DCs.

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Tumor cells acted as an “antigen library” to release all antigens by NIR-trigger.

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Fragmented DNA from tumor cells after photothermal damage activated STING pathway.

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The synergy effect of SHV and aOX40 greatly enhanced anti-tumor immune memory.

Growing tool-kit of photosensitizers for clinical and non-clinical applications

Photosensitizers are photosensitive molecules utilized in clinical and non-clinical applications by taking advantage of light-mediated reactive oxygen generation, which triggers local and systemic cellular toxicity. Photosensitizers are used for diverse biological applications such as spatio-temporal inactivation of a protein in a living system by chromophore-assisted light inactivation, localized cell photoablation, photodynamic and immuno-photodynamic therapy, and correlative light-electron microscopy imaging. Substantial efforts have been made to develop several genetically encoded, chemically synthesized, and nanotechnologically driven photosensitizers for successful implementation in redox biology applications. Genetically encoded photosensitizers (GEPS) or reactive oxygen species (ROS) generating proteins have the advantage of using them in the living system since they can be manipulated by genetic engineering with a variety of target-specific genes for the precise spatio-temporal control of ROS generation. The GEPS variety is limited but is expanding with a variety of newly emerging GEPS proteins. Apart from GEPS, a large variety of chemically- and nanotechnologically-empowered photosensitizers have been developed with a major focus on photodynamic therapy-based cancer treatment alone or in combination with pre-existing treatment methods. Recently, immuno-photodynamic therapy has emerged as an effective cancer treatment method using smartly designed photosensitizers to initiate and engage the patient's immune system so as to empower the photosensitizing effect. In this review, we have discussed various types of photosensitizers, their clinical and non-clinical applications, and implementation toward intelligent efficacy, ROS efficiency, and target specificity in biological systems.

Self-luminescent photodynamic therapy using breast cancer targeted proteins

Despite the potential of photodynamic therapy (PDT), its comprehensive use in cancer treatment has not been achieved because of the nondegradable risks of photosensitizing drugs and limits of light penetration and instrumentation. Here, we present bioluminescence (BL)-induced proteinaceous PDT (BLiP-PDT), through the combination of luciferase and a reactive oxygen species (ROS)-generating protein (Luc-RGP), which is self-luminescent and degradable. After exposure to coelenterazine-h as a substrate for luciferase without external light irradiation, Luc-RGP fused with a small lead peptide-induced breast cancer cell death through the generation of BL-sensitive ROS in the plasma membrane. Even with extremely low light energy, BLiP-PDT exhibited targeted effects in primary breast cancer cells from patients and in in vivo tumor xenograft mouse models. These findings suggest that BLiP-PDT is immediately useful as a promising theranostic approach against various cancers.

NY-ESO-1 Protein Vaccine Combining Alum, CpG ODN, and HH2 Complex Adjuvant Induces Protective and Therapeutic Anti-Tumor Responses in Murine Multiple Myeloma

Background

NY-ESO-1 is an ideal target for multiple myeloma immunotherapy. Alum, CpG ODN and HH2 complex is a safe and effective adjuvant for cancer vaccine.

Methods

We constructed NY-ESO-1 protein vaccine combined with alum, CpG ODN, and HH2 complex adjuvant to immunize the BALB/c mice inoculated with NS-1 murine multiple myeloma cells. Then, we determined the immunogenicity and anti-tumor effects in prophylactic and therapeutic models by analyzing the NY-ESO-1 antibody titer, evaluating IL4/INF-γ expression, and assessing cytotoxic T lymphocytes activities. The side-effects of vaccines were also evaluated.

Results

The group of NY-ESO-1 protein vaccine combining alum, CpG ODN, and HH2 complex adjuvant is more capable of stimulating both humoral and cellular tumor-specific immune responses to prolong the survival of the mice and inhibit tumor growth in prophylactic and therapeutic immunotherapy. The marked side-effects were not detected in immunized mice.

Discussion

The results suggest that alum, CpG ODN, and HH2 complex as a novel immune adjuvant combined cancer vaccine could improve the immunity efficiency in a murine multiple myeloma model.

Synergy between Photodynamic Therapy and Dactinomycin Chemotherapy in 2D and 3D Ovarian Cancer Cell Cultures

In this study we explored the efficacy of combining low dose photodynamic therapy using a porphyrin photosensitiser and dactinomycin, a commonly used chemotherapeutic agent. The studies were carried out on compressed collagen 3D constructs of two human ovarian cancer cell lines (SKOV3 and HEY) versus their monolayer counterparts. An amphiphilc photosensitiser was employed, disulfonated tetraphenylporphine, which is not a substrate for ABC efflux transporters that can mediate drug resistance. The combination treatment was shown to be effective in both monolayer and 3D constructs of both cell lines, causing a significant and synergistic reduction in cell viability. Compared to dactinomycin alone or PDT alone, higher cell kill was found using 2D monolayer culture vs. 3D culture for the same doses. In 3D culture, the combination therapy resulted in 10 and 22 times higher cell kill in SKOV3 and HEY cells at the highest light dose compared to dactinomycin monotherapy, and 2.2 and 5.5 times higher cell kill than PDT alone. The combination of low dose PDT and dactinomycin appears to be a promising way to repurpose dactinomycin and widen its therapeutic applications.

The Potential of Nanobody-Targeted Photodynamic Therapy to Trigger Immune Responses

Nanobody-targeted photodynamic therapy (NB-PDT) has been recently developed as a more tumor-selective approach rather than conventional photodynamic therapy (PDT). NB-PDT uses nanobodies that bind to tumor cells with high affinity, to selectively deliver a photosensitizer, i.e., a chemical which becomes cytotoxic when excited with light of a particular wavelength. Conventional PDT has been reported to be able to induce immunogenic cell death, characterized by the exposure/release of damage-associated molecular patterns (DAMPs) from dying cells, which can lead to antitumor immunity. We explored this aspect in the context of NB-PDT, targeting the epidermal growth factor receptor (EGFR), using high and moderate EGFR-expressing cells. Here we report that, after NB-PDT, the cytoplasmic DAMP HSP70 was detected on the cell membrane of tumor cells and the nuclear DAMP HMGB1 was found in the cell cytoplasm. Furthermore, it was shown that NB-PDT induced the release of the DAMPs HSP70 and ATP, as well as the pro- inflammatory cytokines IL- 1β and IL-6. Conditioned medium from high EGFR-expressing tumor cells treated with NB-PDT led to the maturation of human dendritic cells, as indicated by the upregulation of CD86 and MHC II on their cell surface, and the increased release of IL-12p40 and IL-1β. Subsequently, these dendritic cells induced CD4+ T cell proliferation, accompanied by IFNγ release. Altogether, the initial steps reported here point towards the potential of NB-PDT to stimulate the immune system, thus giving this selective-local therapy a systemic reach.

Preclinical and Clinical Evidence of Immune Responses Triggered in Oncologic Photodynamic Therapy: Clinical Recommendations

Photodynamic therapy (PDT) is an anticancer strategy utilizing light-mediated activation of a photosensitizer (PS) which has accumulated in tumor and/or surrounding vasculature. Upon activation, the PS mediates tumor destruction through the generation of reactive oxygen species and tumor-associated vasculature damage, generally resulting in high tumor cure rates. In addition, a PDT-induced immune response against the tumor has been documented in several studies. However, some contradictory results have been reported as well. With the aim of improving the understanding and awareness of the immunological events triggered by PDT, this review focuses on the immunological effects post-PDT, described in preclinical and clinical studies. The reviewed preclinical evidence indicates that PDT is able to elicit a local inflammatory response in the treated site, which can develop into systemic antitumor immunity, providing long-term tumor growth control. Nevertheless, this aspect of PDT has barely been explored in clinical studies. It is clear that further understanding of these events can impact the design of more potent PDT treatments. Based on the available preclinical knowledge, recommendations are given to guide future clinical research to gain valuable information on the immune response induced by PDT. Such insights directly obtained from cancer patients can only improve the success of PDT treatment, either alone or in combination with immunomodulatory approaches.

Photodynamic Therapy Combined with Antihypoxic Signaling and CpG Adjuvant as an In Situ Tumor Vaccine Based on Metal-Organic Framework Nanoparticles to Boost Cancer Immunotherapy

Photodynamic therapy (PDT) usually aggravates tumor hypoxia, which promotes the survival and metastasis of residue cancer cells; furthermore, although PDT-induced immunogenic death of cancer cells can induce host antitumor responses, such responses are generally weak and not enough to eliminate the residue cancer cells. Here, metal-organic framework (MOF)-based nanoparticles to combine PDT, antihypoxic signaling, and CpG adjuvant as an in situ tumor vaccine to boost host anticancer responses after PDT are designed. The MOF-based nanoparticles are self-assembled from H₂ TCPP and zirconium ions with hypoxia inducible factor (HIF) signaling inhibitor (ACF) and immunologic adjuvant (CpG) loading, and hyaluronic acid (HA) coating on the surface. The final nanoparticles (PCN-ACF-CpG@HA) can specifically target cancer cells overexpressing CD44 receptor though HA; the aggravated hypoxic survival signaling after PDT can be blocked by ACF to inhibit the HIF-1α induced survival and metastasis. With the help of CpG adjuvant, the tumor associated antigens generated from PDT-based cancer cell destruction can initiate strong antitumor immune responses to eliminate residue cancer cells. Taken together, a novel in situ immunostimulatory strategy is designed to synergistically enhance therapeutic effects of PDT by activating host antitumor immune-responses both in vitro and in vivo, which may have great potential for clinical translation in future.

Highly efficient cascading synergy of cancer photo-immunotherapy enabled by engineered graphene quantum dots/photosensitizer/CpG oligonucleotides hybrid nanotheranostics

Currently, photoimmunotherapy based on a theranostic nanoplatform emerges as a promising modality in advanced cancer therapy. In this study, a new type of versatile nanoassemblies (denoted as PC@GCpD(Gd)) was rationally designed by integrating the polydopamine stabilized graphene quantum dots (GQD)-photosensitizer nanocomposites (denoted as GCpD), immunostimulatory polycationic polymer/CpG oligodeoxynucleotide (CpG ODN) nanoparticles (denoted as PC) and Gd³⁺/Cy3 imaging probes for dual magnetic resonance/fluorescence imaging-guided photoimmunotherapy. PC@GCpD(Gd) effectively killed the tumor cells through the amplified photothermal and photodynamic effects mediated by GCpD, and contemporaneously delivered CpG ODN to the targeted endosomal Toll-like receptor 9 (TLR9) to continuously stimulate the secretion of proinflammatory cytokines and the maturation of dendritic cells, thereby resulting in the activation and infiltration of T lymphocytes. As a result, PC@GCpD(Gd) achieved robust inhibition efficiency to almost completely suppress the EMT6 murine mammary cancer model under laser irradiation, implying the superior synergy of combined photoimmunotherapy. Moreover, the in vivo delivery and biodistribution of PC@GCpD(Gd) could be tracked using the high-quality bimodal magnetic resonance imaging/fluorescence imaging. This study highlighted the potent prospect of hybrid PC@GCpD(Gd) nanoassemblies for precise cancer photoimmunotherapy with a cascading effect.

Low power blue LED exposure increases effects of doxorubicin on MDA-MB-231 breast cancer cells

Patients with triple negative breast cancer can develop side effects as a result of chemotherapy. Photodynamic therapy may reduce these side effects if the chemotherapy agent could also act as a photosensitizer. Thus, the aim of this work was to evaluate cytotoxicity and reactive oxygen species production induced by doxorubicin and low power blue LED in breast cancer cultures. Cell viability and reactive oxygen species (ROS) in MDA-MB-231 cultures were evaluated in response to different doxorubicin concentrations and blue LED fluences. Compared with control, cell cultures only incubated with doxorubicin at 25 nM showed 23% of cell viability reduction while its combination with blue LED at 640 J/cm² reduced 40% of cell viability after 24 h. After 48 h, reduction of cell viability raises to 40% in cell cultures only incubated with doxorubicin and 55% when combined with blue LED. Evaluation 30 min after treatment showed that cells incubated with doxorubicin and exposed to blue LED generated 22% more ROS than controls. Those results show that incubation with doxorubicin combined with exposure to low power blue LED is more cytotoxic and more effective to increase ROS levels in MDA-MB-231 cultures than incubation with doxorubicin alone.

A review and outlook in the treatment of osteosarcoma and other deep tumors with photodynamic therapy: from basic to deep

Photodynamic therapy, one of the most promising minimally invasive treatments, has received increasing focus in tumor therapy research, which has been widely applied in treating superficial tumors. Three basic factors - photosensitizer, the light source, and oxidative stress - are responsible for tumor cell cytotoxicity. However, due to insufficient luminous flux and peripheral tissue damage, the utilization of photodynamic therapy is facing a huge limitation in deep tumor therapy. Osteosarcoma is the typical deep tumor, which is the most commonly occurring malignancy in children and adolescents. Despite developments in surgery, high risks of the amputation still threatens the health of osteosarcoma patients. In this review, we summarize recent developments in the field of photodynamic therapy and specifically PDT research in OS treatment modalities. In addition, we also provide some novel suggestions, which could potentially be a breakthrough in PDT-induced OS therapies. PDT has the potential to become an effective therapy while the its limitations still present when applied on the treatment of OS or other types of deep tumors. Thus, more researches and studies in the field are required.

The novel complex combination of alum, CpG ODN and HH2 as adjuvant in cancer vaccine effectively suppresses tumor growth in vivo

Single-component adjuvant is prone to eliciting a specific type of Th1 or Th2 response. So, the development of combinatorial adjuvants inducing a robust mixed Th1/Th2 response is a promising vaccination strategy against cancer. Here, we describe a novel combination of aluminum salts (alum), CpG oligodeoxynucleotide (CpG) and innate defense regulator peptide HH2 for improving anti-tumor immune responses. The CpG-HH2 complex significantly enhanced the production of IFN-γ, TNF-α and IL-1β, promoted the uptake of antigen and strengthened the activation of p38, Erk1/2 and NF-κB in vitro, compared to CpG or HH2 alone. Immunization with NY-ESO-1 antigen plus alum-CpG-HH2 combinatorial adjuvant effectively inhibited tumor growth and reduced tumor burden in prophylactic and therapeutic tumor models and even in passive serum or cellular therapy. In addition, co-administration of NY-ESO-1 with alum-CpG-HH2 combinatorial adjuvant markedly activated NK cell cytotoxicity, induced antibody-dependent cellular cytotoxicity (ADCC), dramatically elicited cytotoxic T lymphocytes (CTLs) response, and increased infiltrating lymphocytes in tumors. Moreover, in vivo depletion of CD8⁺ T cells completely and depletion of NK cells partially blocked the anti-tumor activity of NY-ESO-1-alum-CpG-HH2 immunization. Overall, our results demonstrate a novel adjuvant combination for cancer vaccine with efficient immunomodulation by stimulating innate immunity and mediating adaptive immunity.

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.

"Triple-Punch" Anticancer Strategy Mediated by Near-Infrared Photosensitizer/CpG Oligonucleotides Dual-Dressed and Mitochondria-Targeted Nanographene

Nanomedicine-based combination therapy has sparked a growing interest in clinical disease treatment and pharmaceutical industry. In this study, a mitochondria-targeted and near-infrared (NIR) light-activable multitasking nanographene (i.e., GT/IR820/DP-CpG) was engineered to in situ trigger highly efficient "triple-punch" strategy of cancer photodynamic therapy, photothermal therapy, and immunotherapy. Modification of triphenylphosphonium on graphene made the vehicle specifically guide the NIR dye IR820 home to mitochondria, followed by lysosomes escape in a time-dependent manner. The photoactive nanocomplex generated an abundant reactive oxygen species as well as photothermal heat to ultimately kill cancer cells by inducing mitochondrial collapse and irreversible cell apoptosis upon the NIR laser irradiation. Further introduction of an immunostimulatory conjugate DP-CpG significantly promoted the secretion of proinflammatory cytokines (i.e., interleukin-6, tumor necrosis factor-α, and interferon-γ) and thus improved the immunogenicity of tumors. In vivo studies demonstrated that GT/IR820/DP-CpG remarkably inhibited tumor growth (tumor inhibition rate, ∼88%) resulting from the combinational phototherapeutic effect of IR820 and immunostimulatory activity of DP-CpG, thereby causing negligible toxic effects on mice. Our work provides a new paradigm of architecting organelle-targeted and stimulative nanocomplex for highly efficient cancer photoimmunotherapy.

Radiosensitization by CpG ODN7909 in an epidermoid laryngeal carcinoma Hep-2 cell line

Objective

To evaluate the radiosensitivity effect of CpG oligodeoxyribonucleotide (ODN) 7909 on human epidermoid cancer strain-2 (Hep-2) cells in vitro and discuss the potential for improved radiotherapy treatment in patients with laryngeal squamous cell carcinoma.

Methods

Toll-like receptor (TLR) 9 expression was assessed in Hep-2 cells using Western blots and reverse transcription polymerase chain reaction. Cell Counting Kit-8 was used to detect Hep-2 cell viability at 24 and 48 h following treatment with different CpG ODN7909 concentrations. Cellular colonization was evaluated using microscopy. Cell cycle distribution and apoptosis rate was determined with flow cytometry. Interleukin (IL)-12 and tumour necrosis factor (TNF)-α concentrations were detected by enzyme-linked immunosorbent assay.

Results

Hep-2 cells were found to express TLR9, and CpG ODN7909 treatment suppressed Hep-2 cell viability in a dose- and time-dependent manner. Cell survival curve analyses revealed a sensitivity enhancement ratio of the mean death dose of 1.225 for CpG ODN7909 plus irradiation versus irradiation alone. Furthermore, the population of Gap 2/mitotic-phase cells, apoptosis rate and secreted IL-12 and TNF-α levels were significantly increased in Hep-2 cells treated with CpG ODN7909 plus irradiation versus IR alone.

Conclusion

CpG ODN7909 enhanced the radiosensitivity of Hep-2 cells in vitro.

Oncologic Photodynamic Therapy: Basic Principles, Current Clinical Status and Future Directions

Photodynamic therapy (PDT) is a clinically approved cancer therapy, based on a photochemical reaction between a light activatable molecule or photosensitizer, light, and molecular oxygen. When these three harmless components are present together, reactive oxygen species are formed. These can directly damage cells and/or vasculature, and induce inflammatory and immune responses. PDT is a two-stage procedure, which starts with photosensitizer administration followed by a locally directed light exposure, with the aim of confined tumor destruction. Since its regulatory approval, over 30 years ago, PDT has been the subject of numerous studies and has proven to be an effective form of cancer therapy. This review provides an overview of the clinical trials conducted over the last 10 years, illustrating how PDT is applied in the clinic today. Furthermore, examples from ongoing clinical trials and the most recent preclinical studies are presented, to show the directions, in which PDT is headed, in the near and distant future. Despite the clinical success reported, PDT is still currently underutilized in the clinic. We also discuss the factors that hamper the exploration of this effective therapy and what should be changed to render it a more effective and more widely available option for patients.

Modern trends in biophotonics for clinical diagnosis and therapy to solve unmet clinical needs

This contribution covers recent original research papers in the biophotonics field. The content is organized into main techniques such as multiphoton microscopy, Raman spectroscopy, infrared spectroscopy, optical coherence tomography and photoacoustic tomography, and their applications in the context of fluid, cell, tissue and skin diagnostics. Special attention is paid to vascular and blood flow diagnostics, photothermal and photodynamic therapy, tissue therapy, cell characterization, and biosensors for biomarker detection.

Establishment of specific cytotoxic T lymphocyte culture system and its inhibitory effect on ovarian cancer

The present study aimed to establish a novel method for efficiently inducing cytotoxic T lymphocytes (CTLs) in vitro, in order to develop an immune-based therapy for suppressing and killing ovarian cancer cells with a high safety and efficacy. Peripheral blood mononuclear cells (PBMCs) were stimulated with CpG oligodeoxynucleotide (CpGODN) and ginsenoside Rg1, which were united as an immune adjuvant, and human epidermal growth factor receptor 2 (HER2/neu) antigen peptide, in order to establish a specific CTL culture system in vitro. Chromosome karyotype analysis, growth curve construction and flow cytometric analysis of immune phenotypes, including cluster of differentiation (CD)3, CD4 and CD8, were performed to characterize the stimulated PBMCs in vitro. Subsequently, SKOV3 ovarian cancer cells were treated with the specific CTL culture system in vitro, and MTT assays were performed to test the inhibitory and lethal effects of the CTLs on SKOV3 cells. The number of CTLs was significantly increased from day 7 of stimulation with the specific mixture (CpGODN, ginsenoside Rg1 and HER2/neu) (P<0.01), and plateaued on day 19. Following activation, the number of CD3⁺, CD3⁺CD4⁺ and CD3⁺CD8⁺ cells was significantly increased (P<0.01). The lymphocyte karyotype did not change following exposure to antigen. After treatment with the specific CTL system, the number of SKOV3 cells in the experimental group was significantly reduced compared with that in the control group (P<0.01). The results of the present study suggested that two novel immune adjuvants, CpGODN and ginsenoside Rg1, could be combined with the HER2/neu antigen peptide to establish a specific CTL culture system in vitro. This system demonstrated a high antigen specificity, safety and proliferative ability, and exerted significant lethal and inhibitory effects on SKOV3 cells in vitro.

Targeting Antitumor Immune Response for Enhancing the Efficacy of Photodynamic Therapy of Cancer: Recent Advances and Future Perspectives

Photodynamic therapy (PDT) is a minimally invasive therapeutic strategy for cancer treatment, which can destroy local tumor cells and induce systemic antitumor immune response, whereas, focusing on improving direct cytotoxicity to tumor cells treated by PDT, there is growing interest in developing approaches to further explore the immune stimulatory properties of PDT. In this review we summarize the current knowledge of the innate and adaptive immune responses induced by PDT against tumors, providing evidence showing PDT facilitated-antitumor immunity. Various immunotherapeutic approaches on different cells are reviewed for their effectiveness in improving the treatment efficiency in concert with PDT. Future perspectives are discussed for further enhancing PDT efficiency via intracellular targetable drug delivery as well as optimized experimental model development associated with the study of antitumor immune response.

T-cell mediated anti-tumor immunity after photodynamic therapy: why does it not always work and how can we improve it?

Photodynamic therapy (PDT) uses the combination of non-toxic photosensitizers and harmless light to generate reactive oxygen species that destroy tumors by a combination of direct tumor cell killing, vascular shutdown, and activation of the immune system. It has been shown in some animal models that mice that have been cured of cancer by PDT, may exhibit resistance to rechallenge. The cured mice can also possess tumor specific T-cells that recognize defined tumor antigens, destroy tumor cells in vitro, and can be adoptively transferred to protect naïve mice from cancer. However, these beneficial outcomes are the exception rather than the rule. The reasons for this lack of consistency lie in the ability of many tumors to suppress the host immune system and to actively evade immune attack. The presence of an appropriate tumor rejection antigen in the particular tumor cell line is a requisite for T-cell mediated immunity. Regulatory T-cells (CD25+, Foxp3+) are potent inhibitors of anti-tumor immunity, and their removal by low dose cyclophosphamide can potentiate the PDT-induced immune response. Treatments that stimulate dendritic cells (DC) such as CpG oligonucleotide can overcome tumor-induced DC dysfunction and improve PDT outcome. Epigenetic reversal agents can increase tumor expression of MHC class I and also simultaneously increase expression of tumor antigens. A few clinical reports have shown that anti-tumor immunity can be generated by PDT in patients, and it is hoped that these combination approaches may increase tumor cures in patients.

CpG oligodeoxyribonucleotide 7909 enhances radiosensitivity via downregulating Oct-4 expression in radioresistant lung cancer cells

Radiotherapy is a powerful cure for local advanced non-small cell lung cancer. However, radioresistance and tumor relapse still occur in a high proportion of patients. Octamer-4 (Oct-4), a transcription factor of the POU family, plays a key role in maintaining chemoradioresistant properties and regulating cancer progression. In this study, we demonstrated that Oct-4 expression was significantly increased in radioresistant H460 (H460R) cell line. CpG oligodeoxyribonucleotide (CpG-ODN) 7909 sensitized H460R cells when combined with irradiation treatment. The clonogenic capacity was significantly decreased, and the values of D0 and Dq were lower than those of irradiation alone group. The sensitive enhancement ratio (SER) of D0 was 1.224. This combined treatment led to a dramatic reduction in Oct-4 expression in a dose-dependent manner and also showed increased percentage of cells in the radiosensitive G2/M phase relative to either treatment alone. These results identified that Oct-4 was involved in radioresistance. CpG-ODN 7909 could enhance radiosensitivity partly through downregulating Oct-4 expression in radioresistant lung cancer cells.

Breast cancer as photodynamic therapy target: Enhanced therapeutic efficiency by overview of tumor complexity

Photodynamic therapy is a minimally invasive and clinically approved procedure for eliminating selected malignant cells with specific light activation of a photosensitizer agent. Whereas interstitial and intra-operative approaches have been investigated for the ablation of a broad range of superficial or bulky solid tumors such as breast cancer, the majority of approved photodynamic therapy protocols are for the treatment of superficial lesions of skin and luminal organs. This review article will discuss recent progress in research focused mainly on assessing the efficacies of various photosensitizers used in photodynamic therapy, as well as the combinatory strategies of various therapeutic modalities for improving treatments of parenchymal and/or stromal tissues of breast cancer solid tumors. Cytotoxic agents are used in cancer treatments for their effect on rapidly proliferating cancer cells. However, such therapeutics often lack specificity, which can lead to toxicity and undesirable side effects. Many approaches are designed to target tumors. Selective therapies can be established by focusing on distinctive intracellular (receptors, apoptotic pathways, multidrug resistance system, nitric oxide-mediated stress) and environmental (glucose, pH) differences between tumor and healthy tissue. A rational design of effective combination regimens for breast cancer treatment involves a better understanding of the mechanisms and molecular interactions of cytotoxic agents that underlie drug resistance and sensitivity.

Combinatorial photothermal and immuno cancer therapy using chitosan-coated hollow copper sulfide nanoparticles

Near-infrared light-responsive inorganic nanoparticles have been shown to enhance the efficacy of cancer photothermal ablation therapy. However, current nanoparticle-mediated photothermal ablation is more effective in treating local cancer at the primary site than metastatic cancer. Here, we report the design of a near-infrared light-induced transformative nanoparticle platform that combines photothermal ablation with immunotherapy. The design is based on chitosan-coated hollow CuS nanoparticles that assemble the immunoadjuvants oligodeoxynucleotides containing the cytosine-guanine (CpG) motifs. Interestingly, these structures break down after laser excitation, reassemble, and transform into polymer complexes that improve tumor retention of the immunotherapy. In this "photothermal immunotherapy" approach, photothermal ablation-induced tumor cell death reduces tumor growth and releases tumor antigens into the surrounding milieu, while the immunoadjuvants potentiate host antitumor immunity. Our results indicated that combined photothermal immunotherapy is more effective than either immunotherapy or photothermal therapy alone against primary treated and distant untreated tumors in a mouse breast cancer model. These hollow CuS nanoparticles are biodegradable and can be eliminated from the body after laser excitation.