Nanoparticle Phototherapy in the Era of Cancer Immunotherapy

Silver Nanoparticles Improve Fluorophore Photostability: Application to a Hypericin Study

Protection against the negative effects of solar radiation involves using cosmetics with a UV filter, but visible radiation can also have negative effects. We use dietary supplements and take medications; unfortunately, many of them contain substances that degrade under the influence of visible light, which transform into chemical compounds harmful to health. Manufacturers often include information on the prohibition of exposure to sunlight on the packaging, but consumers often do not read the product leaflet. The solution to this problem may be the addition of silver particles to preparations. In the presented article, we proposed the use of silver nanoparticles to reduce the photobleaching and photoreaction of fluorophore, while increasing the fluorescence intensity. For our research, we used a compound that is particularly sensitive to radiation: hypericin.

Rational Design of a Hetero-multinuclear Gadolinium(III)-Copper(II) Complex: Integrating Magnetic Resonance Imaging, Photoacoustic Imaging, Mild Photothermal Therapy, Chemotherapy and Immunotherapy of Cancer

For more accurate diagnosis and effective treatment of cancer, we proposed to develop a hetero-multinuclear metal complex based on the property of apoferritin (AFt) for targeting tumor theranostics by integrating dual-modality imaging diagnosis and multimodality therapy. To this end, we rational designed and synthesized a trinuclear Gd(III)-Cu(II) thiosemicarbazone complex (Gd-2Cu) and then constructed a Gd-2Cu@AFt nanoparticle (NP) delivery system. Gd-2Cu/Gd-2Cu@AFt NPs not only had significant T1-weighted magnetic resonance imaging and photoacoustic imaging of the tumor but also effectively inhibited tumor growth through a combination of mild photothermal therapy, chemotherapy, and immunotherapy. Gd-2Cu@AFt NPs optimized the behavior of imaging diagnosis and therapy of Gd-2Cu, improved its targeting ability, and reduced the side effects in vivo. Besides, we revealed and clarified the anticancer mechanism of Gd-2Cu: interrupting energy metabolism of the tumor cell, inducing apoptosis of the tumor cell, and activating a systemic immune response by inducing immunogenic cell death of cancer cells.

Design Principles for Smart Linear Polymer Ligand Carriers with Efficient Transcellular Transport Capabilities

The surface functionalization of polymer-mediated drug/gene delivery holds immense potential for disease therapy. However, the design principles underlying the surface functionalization of polymers remain elusive. In this study, we employed computer simulations to demonstrate how the stiffness, length, density, and distribution of polymer ligands influence their penetration ability across the cell membrane. Our simulations revealed that the stiffness of polymer ligands affects their ability to transport cargo across the membrane. Increasing the stiffness of polymer ligands can promote their delivery across the membrane, particularly for larger cargoes. Furthermore, appropriately increasing the length of polymer ligands can be more conducive to assisting cargo to enter the lower layer of the membrane. Additionally, the distribution of polymer ligands on the surface of the cargo also plays a crucial role in its transport. Specifically, the one-fourth mode and stripy mode distributions of polymer ligands exhibited higher penetration ability, assisting cargoes in penetrating the membrane. These findings provide biomimetic inspiration for designing high-efficiency functionalization polymer ligands for drug/gene delivery.

Gold nanoparticles-mediated photothermal and photodynamic therapies for cancer

Cancer remains one of the major causes of death globally, with one out of every six deaths attributed to the disease. The impact of cancer is felt on psychological, physical, and financial levels, affecting individuals, communities, and healthcare institutions. Conventional cancer treatments have many challenges and inadequacies. Nanomedicine, however, presents a promising solution by not only overcoming these problems but also offering the advantage of combined therapy for treatment-resistant cancers. Nanoparticles specifically engineered for use in nanomedicine can be efficiently targeted to cancer cells through a combination of active and passive techniques, leading to superior tumor-specific accumulation, enhanced drug availability, and reduced systemic toxicity. Among various nanoparticle formulations designed for cancer treatment, gold nanoparticles have gained prominence in the field of nanomedicine due to their photothermal, photodynamic, and immunologic effects without the need for photosensitizers or immunotherapeutic agents. To date, there is no comprehensive literature review that focuses on the photothermal, photodynamic, and immunologic effects of gold nanoparticles. In this review, significant attention has been devoted to examining the parameters pertaining to the structure of gold nanoparticles and laser characteristics, which play a crucial role in influencing the efficacy of photothermal therapy (PTT) and photodynamic therapy (PDT). Moreover, this article provides insights into the success of PTT and PDT mediated by gold nanoparticles in primary cancer treatment, as well as the immunological effects of PTT and PDT on metastasis and recurrence, providing a promising strategy for cancer therapy. In summary, gold nanoparticles, with their unique properties, have the potential for clinical application in various cancer therapies, including the treatment of primary cancer, recurrence and metastasis.

Recent progress on polySarcosine as an alternative to PEGylation: Synthesis and biomedical applications

Biotherapeutic PEGylation to prolong action of medications has gained popularity over the last decades. Various hydrophilic natural polymers have been developed to tackle the drawbacks of PEGylation, such as its accelerated blood clearance and non-biodegradability. Polypeptoides, such as polysarcosine (pSar), have been explored as hydrophilic substitutes for PEG. pSar has PEG-like physicochemical characteristics such as water solubility and no reported cytotoxicity and immunogenicity. This review discusses pSar derivatives, synthesis, characterization approaches, biomedical applications, in addition to the challenges and future perspectives of pSar based biomaterials as an alternative to PEG.

Gene and Photothermal Combination Therapy: Principle, Materials, and Amplified Anticancer Intervention

Gene therapy (GT) and photothermal therapy (PTT) have emerged as promising alternatives to chemotherapy and radiotherapy for cancer treatment, offering noninvasiveness and reduced side effects. However, their efficacy as standalone treatments is limited. GT exhibits slow response rates, while PTT is confined to local tumor ablation. The convergence of GT and PTT, known as GT-PTT, facilitated by photothermal gene nanocarriers, has attracted considerable attention across various disciplines. In this integrated approach, GT reciprocates PTT by sensitizing cellular response to heat, while PTT benefits GT by improving gene translocation, unpacking, and expression. Consequently, this integration presents a unique opportunity for cancer therapy with rapid response and improved effectiveness. Extensive efforts over the past few years have been dedicated to the development of GT-PTT, resulting in notable achievements and rapid progress from the laboratory to potential clinical applications. This comprehensive review outlines recent advances in GT-PTT, including synergistic mechanisms, material systems, imaging-guided therapy, and anticancer applications. It also explores the challenges and future prospects in this nascent field. By presenting innovative ideas and insights into the implementation of GT-PTT for enhanced cancer therapy, this review aims to inspire further progress in this promising area of research.

Developing a Hetero-Trinuclear Erbium(III)-Copper(II) Complex Based on Apoferritin: Targeted Photoacoustic Imaging and Multimodality Therapy of Tumor

For the integration of targeted diagnosis and treatment of tumor, we innovatively designed and synthesized a single-molecule hetero-multinuclear Er(III)-Cu(II) complex (ErCu2) and then constructed an ErCu2@apoferritin (AFt) nanoparticle (NP) delivery system. ErCu2 and ErCu2@AFt NPs not only provided an evident photoacoustic imaging (PAI) signal of the tumor but also effectively inhibited tumor growth by integrating photothermal therapy, chemotherapy, and immunotherapy. ErCu2@AFt NPs improved the targeting ability and decreased the systemic toxicity of ErCu2 in vivo. Furthermore, we confirmed that ErCu2 and ErCu2@AFt NPs inhibited tumor growth by inducing apoptosis and autophagy of tumor cells and activating the immune system. The study not only provides a novel strategy to develop therapeutic metal agents but also reveals their potential for targeted accurate diagnosis and multimodality therapy of cancer.

Remodeling the tumor immune microenvironment via siRNA therapy for precision cancer treatment

How to effectively transform the pro-oncogenic tumor microenvironments (TME) surrounding a tumor into an anti-tumoral never fails to attract people to study. Small interfering RNA (siRNA) is considered one of the most noteworthy research directions that can regulate gene expression following a process known as RNA interference (RNAi). The research about siRNA delivery targeting tumor cells and TME has been on the rise in recent years. Using siRNA drugs to silence critical proteins in TME was one of the most efficient solutions. However, the manufacture of a siRNA delivery system faces three major obstacles, i.e., appropriate cargo protection, accurately targeted delivery, and site-specific cargo release. In the following review, we summarized the pharmacological actions of siRNA drugs in remolding TME. In addition, the delivery strategies of siRNA drugs and combination therapy with siRNA drugs to remodel TME are thoroughly discussed. In the meanwhile, the most recent advancements in the development of all clinically investigated and commercialized siRNA delivery technologies are also presented. Ultimately, we propose that nanoparticle drug delivery siRNA may be the future research focus of oncogene therapy. This summary offers a thorough analysis and roadmap for general readers working in the field.

Recent Progress of Preparation Strategies in Organic Nanoparticles for Cancer Phototherapeutics

Phototherapy has the advantages of being a highly targeted, less toxic, less invasive, and repeatable treatment, compared with conventional treatment methods such as surgery, chemotherapy, and radiotherapy. The preparation strategies are significant in order to determine the physical and chemical properties of nanoparticles. However, choosing appropriate preparation strategies to meet applications is still challenging. This review summarizes the recent progress of preparation strategies in organic nanoparticles, mainly focusing on the principles, methods, and advantages of nanopreparation strategies. In addition, typical examples of cancer phototherapeutics are introduced in detail to inform the choice of appropriate preparation strategies. The relative future trend and outlook are preliminarily proposed.

Nanoparticle-mediated synergistic anticancer effect of ferroptosis and photodynamic therapy: Novel insights and perspectives

Current antitumor monotherapy has many limitations, highlighting the need for novel synergistic anticancer strategies. Ferroptosis is an iron-dependent form of nonapoptotic cell death that plays a pivotal regulatory role in tumorigenesis and treatment. Photodynamic therapy (PDT) causes irreversible chemical damage to target lesions and is widely used in antitumor therapy. However, PDT's effectiveness is usually hindered by several obstacles, such as hypoxia, excess glutathione (GSH), and tumor resistance. Ferroptosis improves the anticancer efficacy of PDT by increasing oxygen and reactive oxygen species (ROS) or reducing GSH levels, and PDT also enhances ferroptosis induction due to the ROS effect in the tumor microenvironment (TME). Strategies based on nanoparticles (NPs) can subtly exploit the potential synergy of ferroptosis and PDT. This review explores recent advances and current challenges in the landscape of the underlying mechanisms regulating ferroptosis and PDT, as well as nano delivery system-mediated synergistic anticancer activity. These include polymers, biomimetic materials, metal organic frameworks (MOFs), inorganics, and carrier-free NPs. Finally, we highlight future perspectives of this novel emerging paradigm in targeted cancer therapies.

Metal-Organic Frameworks Applications in Synergistic Cancer Photo-Immunotherapy

Conventional cancer therapies, such as radiotherapy and chemotherapy, can have long-term side effects. Phototherapy has significant potential as a non-invasive alternative treatment with excellent selectivity. Nevertheless, its applicability is restricted by the availability of effective photosensitizers and photothermal agents, and its low efficacy when it comes to avoiding metastasis and tumor recurrence. Immunotherapy can promote systemic antitumoral immune responses, acting against metastasis and recurrence; however, it lacks the selectivity displayed by phototherapy, sometimes leading to adverse immune events. The use of metal-organic frameworks (MOFs) in the biomedical field has grown significantly in recent years. Due to their distinct properties, including their porous structure, large surface area, and inherent photo-responsive properties, MOFs can be particularly useful in the fields of cancer phototherapy and immunotherapy. MOF nanoplatforms have successfully demonstrated their ability to address several drawbacks associated with cancer phototherapy and immunotherapy, enabling an effective and low-side-effect combinatorial synergistical treatment for cancer. In the coming years, new advancements in MOFs, particularly regarding the development of highly stable multi-function MOF nanocomposites, may revolutionize the field of oncology.

Quinoid Conjugated Polymer Nanoparticles with NIR-II Absorption Peak Toward Efficient Photothermal Therapy

Recently, extensive efforts have been devoted to the development of the second near-infrared bio-window (NIR-II, 1000-1700 nm) theranostic agents owing to the excellent tissue-penetration capability of NIR-II light. The exploration of organic NIR-II photothermal therapy materials, especially those with absorption peak over 1000 nm, is an appealing yet significantly challenging task. Herein, we have designed conjugated polymer nanoparticles (PIS NPs) with NIR-II absorption peak at 1026 nm through a combined strategy of introducing quinoid donor-acceptor (D-A) structures, constructing intramolecular "conformational locks" and extending the conjugation area to narrow the band gap. Irradiated at 1064 nm, PIS NPs showed remarkable photothermal conversion performance for efficient photothermal ablation of tumor cells in vitro and in vivo. This study provides useful insights into the rational design of organic NIR-II photothermal agents based on multiple strategies.

Gold Triangular Nanoprisms: Anisotropic Plasmonic Materials with Unique Structures and Properties

As a novel type of anisotropic inorganic nanomaterials, gold triangular nanoprisms (AuTNPs) have been widely studied for their well-defined structures and excellent plasmonic properties. This review starts with synthetic methodology, combing through the early thermal solution method to the mature seed-mediated method and seedless method. The possible mechanisms proposed by predecessors and the problems needed to be solved are also arranged. Along with this, the important morphological evolution process of AuTNPs during synthesis and post-synthesis stages are revealed, which is of great significance for further understanding the structure of AuTNPs and developing new synthesis strategies. Finally, the applications of AuTNPs, especially associated with plasmonic properties, are listed and summarized where surface-enhanced Raman scattering (SERS), catalysis, phototherapy and biosensor are included, so that researchers can quickly comprehend the current situation, and provide a basis for further development and exploration of AuTNPs.

Dendritic Plasmonic CuPt Alloys for Closed-Loop Multimode Cancer Therapy with Remarkably Enhanced Efficacy

The outcome of laser-triggered plasmons-induced phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), is significantly limited by the hypoxic tumor microenvironment and the upregulation of heat shock proteins (HSPs) in response to heat stress. Mitochondria, the biological battery of cells, can serve as an important breakthrough to overcome these obstacles. Herein, dendritic triangular pyramidal plasmonic CuPt alloys loaded with heat-sensitive NO donor N, N'-di-sec-butyl-N, N'-dinitroso-1,4-phenylenediamine (BNN) is developed. Under 808 nm laser irradiation, plasmonic CuPt can generate superoxide anion free radicals (·O₂ ^- ) and heat simultaneously. The heat generated can then trigger the release of NO gas, which not only enables gas therapy but also damages the mitochondrial respiratory chain. Impaired mitochondrial respiration leads to reduced oxygen consumption and insufficient intracellular ATP supply, which effectively alleviates tumor hypoxia and undermines the synthesis of HSPs, in turn boosting plasmonic CuPt-based PDT and mild PTT. Additionally, the generated NO and ·O₂ ^- can react to form more cytotoxic peroxynitrite (ONOO^- ). This work describes a plasmonic CuPt@BNN (CPB) triggered closed-loop NO gas, free radicals, and mild photothermal therapy strategy that is highly effective at reciprocally promoting antitumor outcomes.

Graphene Quantum Dots Modified Upconversion Nanoparticles for Photodynamic Therapy

Photodynamic therapy (PDT), as a novel technique, has been extensively employed in cancer treatment by utilizing reactive oxygen species (ROS) to kill malignant cells. However, most photosensitizers (PSs) are short of ROS yield and affect the therapeutic effect of PDT. Thus, there is a substantial demand for the development of novel PSs for PDT to advance its clinical translation. In this study, we put forward a new strategy for PS synthesis via modifying graphene quantum dots (GQDs) on the surface of rare-earth elements doped upconversion nanoparticles (UCNPs) to produce UCNPs@GQDs with core-shell structure. This new type of PSs combined the merits of UCNPs and GQDs and produced ROS efficiently under near-infrared light excitation to trigger the PDT process. UCNPs@GQDs exhibited high biocompatibility and obvious concentration-dependent PDT efficiency, shedding light on nanomaterials-based PDT development.

Iron Oxide-Au Magneto-Plasmonic Heterostructures: Advances in Their Eco-Friendly Synthesis

In recent years, nanotechnologies have attracted considerable interest, especially in the biomedical field. Among the most investigated particles, magnetic based on iron oxides and Au nanoparticles gained huge interest for their magnetic and plasmonic properties, respectively. These nanoparticles are usually produced starting from processes and reagents that can be the cause of potential human health and environmental concerns. For this reason, there is a need to develop simple, green, low-cost, and non-toxic synthesis methods and reagents. This review aims at providing an overview of the most recently developed processes to produce iron oxide magnetic nanoparticles, Au nanoparticles, and their magneto-plasmonic heterostructures using eco-friendly approaches, focusing the attention on the microorganisms and plant-assisted syntheses and showing the first results of the development of magneto-plasmonic heterostructures.

Photocontrolled Spatiotemporal Delivery of DNA Immunomodulators for Enhancing Membrane-Targeted Tumor Photodynamic Immunotherapy

Immunotherapy is emerging as a paradigm-shifting modality for treatment cancer. However, systemic administration of immunomodulators is usually accompanied by extra-tumor toxicity and adverse immune effects. Precise delivery of immunomodulators with a highly controllable system may provide a solution for this issue. Here, we developed a photocontrolled DNA nanomedicine for localized delivery of DNA immunomodulators to enhance membrane-targeted photodynamic immunotherapy. Specifically, the DNA nanomedicine is composed of long tandemly repeated functional DNA sequences (PDL1 aptamers and CpG) with a photosensitizer (TMPyP₄) inserted into the DNA structure, providing high drug-loading capacity. By blocking the surface PDL1 aptamer with a pHLIP-modified cDNA, the DNA nanomedicine does not induce any obvious immune response and can be specifically delivered and anchored to the tumor membrane. Under localized irradiation, photodynamically generated reactive oxygen species (ROS) causes breakage of DNA sequences, which triggers the collapse of the nanostructure and release of internal DNA immunomodulators. Under localized illumination, photodynamically generated ROS can cause DNA sequence breaks, triggering the collapse of nanostructures and the release of internal DNA immunomodulators thus enhancing membrane-targeted photodynamic immunotherapy. We have demonstrated that the developed DNA nanomedicine can drive efficient immune responses in tumor tissue without perceptibly interfering off-tumor immunity, resulting in efficient antitumor treatment while mitigating systemic toxicity.

How to Treat Melanoma? The Current Status of Innovative Nanotechnological Strategies and the Role of Minimally Invasive Approaches like PTT and PDT

Melanoma is the most aggressive type of skin cancer, the incidence and mortality of which are increasing worldwide. Its extensive degree of heterogeneity has limited its response to existing therapies. For many years the therapeutic strategies were limited to surgery, radiotherapy, and chemotherapy. Fortunately, advances in knowledge have allowed the development of new therapeutic strategies. Despite the undoubted progress, alternative therapies are still under research. In this context, nanotechnology is also positioned as a strong and promising tool to develop nanosystems that act as drug carriers and/or light absorbents to potentially improve photothermal and photodynamic therapies outcomes. This review describes the latest advances in nanotechnology field in the treatment of melanoma from 2011 to 2022. The challenges in the translation of nanotechnology-based therapies to clinical applications are also discussed. To sum up, great progress has been made in the field of nanotechnology-based therapies, and our understanding in this field has greatly improved. Although few therapies based on nanoparticulate systems have advanced to clinical trials, it is expected that a large number will come into clinical use in the near future. With its high sensitivity, specificity, and multiplexed measurement capacity, it provides great opportunities to improve melanoma treatment, which will ultimately lead to enhanced patient survival rates.

Radiodynamic therapy with CsI(na)@MgO nanoparticles and 5-aminolevulinic acid

Background

Radiodynamic therapy (RDT) holds the potential to overcome the shallow tissue penetration issue associated with conventional photodynamic therapy (PDT). To this end, complex and sometimes toxic scintillator–photosensitizer nanoconjugates are often used, posing barriers for large-scale manufacturing and regulatory approval.

Methods

Herein, we report a streamlined RDT strategy based on CsI(Na)@MgO nanoparticles and 5-aminolevulinic acid (5-ALA). 5-ALA is a clinically approved photosensitizer, converted to protoporphyrin IX (PpIX) in cancer cells’ mitochondria. CsI(Na)@MgO nanoparticles produce strong ~ 410 nm X-ray luminescence, which matches the Soret band of PpIX. We hypothesize that the CsI(Na)@MgO-and-5-ALA combination can mediate RDT wherein mitochondria-targeted PDT synergizes with DNA-targeted irradiation for efficient cancer cell killing. Because scintillator nanoparticles and photosensitizer are administered separately, the approach forgoes issues such as self-quenching or uncontrolled release of photosensitizers.

Results

When tested in vitro with 4T1 cells, the CsI(Na)@MgO and 5-ALA combination elevated radiation-induced reactive oxygen species (ROS), enhancing damages to mitochondria, DNA, and lipids, eventually reducing cell proliferation and clonogenicity. When tested in vivo in 4T1 models, RDT with the CsI(Na)@MgO and 5-ALA combination significantly improved tumor suppression and animal survival relative to radiation therapy (RT) alone. After treatment, the scintillator nanoparticles, made of low-toxic alkali and halide elements, were efficiently excreted, causing no detectable harm to the hosts.

Conclusions

Our studies show that separately administering CsI(Na)@MgO nanoparticles and 5-ALA represents a safe and streamlined RDT approach with potential in clinical translation.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01537-z.

NIR-II phototherapy agents with aggregation-induced emission characteristics for tumor imaging and therapy

As one of the major public health concerns, malignant tumors threaten people's lives. With the increasing demand for early accurate diagnosis and the safe treatment of tumors, non-invasive optical imaging (including fluorescence imaging and photoacoustic imaging) and phototherapy (including photothermal therapy and photodynamic therapy) have received much attention. In particular, light in the near-infrared second region (NIR-II) has been attracting research interest, owing to its deep penetration, minimal tissue autofluorescence, and decreased tissue absorption and scattering. Among all biological materials, organic nanomaterials with aggregation-induced emission (AIE) properties have attracted significant attention, owing to various incomparable advantages, such as high brightness, good photostability, tunable photophysical properties, and good biosafety. To modulate the working optical region of AIE molecules to the NIR-II region, many researchers have tried a variety of methods in recent years, and the focus of this review is to summarize the three most common methods from the perspective of molecular design strategies. In addition, this article briefly reviews the recent five-year progress of NIR-II AIE luminophores in tumor imaging and phototherapy applications. The research status is also summarized and prospected, with the hope of contributing to further research.

Diselenium-bridged covalent organic framework with pH/GSH/photo-triple-responsiveness for highly controlled drug release toward joint chemo/photothermal/chemodynamic cancer therapy

Here, a novel joint chemo/photothermal/chemodynamic therapy was developed using a pH/GSH/photo triple-responsive 2D-covalent organic framework (COFs) drug carriers for passive target treatment of tumor with extraordinarily high efficiency. The well-designed...

Nanoconjugates to enhance PDT-mediated cancer immunotherapy by targeting the indoleamine-2,3-dioxygenase pathway

BACKGROUND

Photodynamic therapy (PDT) may elicit antitumor immune response in addition to killing cancer cells. However, PDT as a monotherapy often fails to induce a strong immunity. Immune checkpoint inhibitors, which selectively block regulatory axes, may be used in combination with PDT to improve treatment outcomes. Indoleamine 2,3-dioxygenase (IDO) is an immunoregulatory enzyme and an important meditator of tumor immune escape. Combination therapy with PDT and IDO-targeted immune checkpoint blockage is promising but has been seldom been explored.

METHODS

Herein we report a composite nanoparticle that allows for simultaneous delivery of photosensitizer and IDO inhibitor. Briefly, we separately load ZnF16Pc, a photosensitizer, and NLG919, an indoleamine 2,3-dioxygenase (IDO) inhibitor, into ferritin and poly(lactide-co-glycolic)-block-poly(ethylene glycol) (PEG-PLGA) nanoparticles; we then conjugate these two compartments to form a composite nanoparticle referred to as PPF NPs. We tested combination treatment with PPF NPs first in vitro and then in vivo in B16F10-tumor bearing C57/BL6 mice.

RESULTS

Our results showed that PPF NPs can efficiently encapsulate both ZnF16Pc and NLG919. In vivo studies found that the combination treatment led to significantly improved tumor suppression and animal survival. Moreover, the treatment increased tumor infiltration of CD8+ T cells, while reducing frequencies of MDSCs and Tregs. 30% of the animals showed complete tumor eradication, and they successfully rejected a second tumor inoculation. Overall, our studies introduce a unique composite nanoplatform that allows for co-delivery of photosensitizer and IDO inhibitor with minimal inter-species interference, which is ideal for combination therapy.