Anti-tumor immunity of BAM-SiPc-mediated vascular photodynamic therapy in a BALB/c mouse model

Photodynamic Therapy and Adaptive Immunity Induced by Reactive Oxygen Species: Recent Reports

Cancer is one of the most significant causes of death worldwide. Despite the rapid development of modern forms of therapy, results are still unsatisfactory. The prognosis is further worsened by the ability of cancer cells to metastasize. Thus, more effective forms of therapy, such as photodynamic therapy, are constantly being developed. The photodynamic therapeutic regimen involves administering a photosensitizer that selectively accumulates in tumor cells or is present in tumor vasculature prior to irradiation with light at a wavelength corresponding to the photosensitizer absorbance, leading to the generation of reactive oxygen species. Reactive oxygen species are responsible for the direct and indirect destruction of cancer cells. Photodynamically induced local inflammation has been shown to have the ability to activate an adaptive immune system response resulting in the destruction of tumor lesions and the creation of an immune memory. This paper focuses on presenting the latest scientific reports on the specific immune response activated by photodynamic therapy. We present newly discovered mechanisms for the induction of the adaptive response by analyzing its various stages, and the possible difficulties in generating it. We also present the results of research over the past 10 years that have focused on improving the immunological efficacy of photodynamic therapy for improved cancer therapy.

Trial watch: an update of clinical advances in photodynamic therapy and its immunoadjuvant properties for cancer treatment

Photodynamic therapy (PDT) is a medical treatment used to target solid tumors, where the administration of a photosensitizing agent and light generate reactive oxygen species (ROS), thus resulting in strong oxidative stress that selectively damages the illuminated tissues. Several preclinical studies have demonstrated that PDT can prime the immune system to recognize and attack cancer cells throughout the body. However, there is still limited evidence of PDT-mediated anti-tumor immunity in clinical settings. In the last decade, several clinical trials on PDT for cancer treatment have been initiated, indicating that significant efforts are being made to improve current PDT protocols. However, most of these studies disregarded the immunological dimension of PDT. The immunomodulatory properties of PDT can be combined with standard therapy and/or emerging immunotherapies, such as immune checkpoint blockers (ICBs), to achieve better disease control. Combining PDT with immunotherapy has shown synergistic effects in some preclinical models. However, the value of this combination in patients is still unknown, as the first clinical trials evaluating the combination of PDT with ICBs are just being initiated. Overall, this Trial Watch provides a summary of recent clinical information on the immunomodulatory properties of PDT and ongoing clinical trials using PDT to treat cancer patients. It also discusses the future perspectives of PDT for oncological indications.

Reaching new lights: a review on photo-controlled nanomedicines and their in vivo evaluation

The selective and efficient delivery of bioactive molecules to sites of interest remains a formidable challenge in medicine. In recent years, it has been shown that stimuli-responsive drug delivery systems display several advantages over traditional drug administration such as an improved pharmacokinetic profile and the desirable ability to gain control over release. Light emerged as one of the most powerful stimuli due to its high biocompatibility, spatio-temporal control, and non-invasiveness. On the road to clinical translation, various chemical systems of high complexity have been reported with the aim to improve efficacy, safety, and versatility of drug delivery under complex biological conditions. For future research on the chemical design of such photo-controlled nanomedicines, it is essential to gain an understanding of their in vivo translation and efficiency. Here, we discuss photo-controlled nanomedicines that have been evaluated in vivo and provide an overview of the state-of-the-art that should guide future research design.

Which cell death modality wins the contest for photodynamic therapy of cancer?

Photodynamic therapy (PDT) was discovered more than 100 years ago. Since then, many protocols and agents for PDT have been proposed for the treatment of several types of cancer. Traditionally, cell death induced by PDT was categorized into three types: apoptosis, cell death associated with autophagy, and necrosis. However, with the discovery of several other regulated cell death modalities in recent years, it has become clear that this is a rather simple understanding of the mechanisms of action of PDT. New observations revealed that cancer cells exposed to PDT can pass through various non-conventional cell death pathways, such as paraptosis, parthanatos, mitotic catastrophe, pyroptosis, necroptosis, and ferroptosis. Nowadays, immunogenic cell death (ICD) has become one of the most promising ways to eradicate tumor cells by activation of the T-cell adaptive immune response and induction of long-term immunological memory. ICD can be triggered by many anti-cancer treatment methods, including PDT. In this review, we critically discuss recent findings on the non-conventional cell death mechanisms triggered by PDT. Next, we emphasize the role and contribution of ICD in these PDT-induced non-conventional cell death modalities. Finally, we discuss the obstacles and propose several areas of research that will help to overcome these challenges and lead to the development of highly effective anti-cancer therapy based on PDT.

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.

Nanotechnology synergized immunoengineering for cancer

Novel strategies modulating the immune system yielded enhanced anticancer responses and improved cancer survival. Nevertheless, the success rate of immunotherapy in cancer treatment has been below expectation(s) due to unpredictable efficacy and off-target effects from systemic dosing of immunotherapeutic(s). As a result, there is an unmet clinical need for improving conventional immunotherapy. Nanotechnology offers several new strategies, multimodality, and multiplex biological targeting advantage to overcome many of these challenges. These efforts enable programming the pharmacodynamics, pharmacokinetics, and delivery of immunomodulatory agents/co-delivery of compounds to prime at the tumor sites for improved therapeutic benefits. This review provides an overview of the design and clinical principles of biomaterials driven nanotechnology and their potential use in personalized nanomedicines, vaccines, localized tumor modulation, and delivery strategies for cancer immunotherapy. In this review, we also summarize the latest highlights and recent advances in combinatorial therapies availed in the treatment of cold and complicated tumors. It also presents key steps and parameters implemented for clinical success. Finally, we analyse, discuss, and provide clinical perspectives on the integrated opportunities of nanotechnology and immunology to achieve synergistic and durable responses in cancer treatment.

Enhancement of innate and adaptive anti-tumor immunity by serum obtained from vascular photodynamic therapy-cured BALB/c mouse

Photodynamic therapy (PDT) is a clinically approved treatment for various types of cancer. Besides killing the tumor cells directly, PDT has also been reported to trigger anti-tumor immunity. In our previous study, BAM-SiPc-based PDT was shown to induce immunogenic cell death on CT26 murine colon tumor cells in vitro. Using the BALB/c mouse animal model and a vascular-PDT (VPDT) approach, it could also eradicate tumor in ∼ 70% of tumor-bearing mice and elicit an anti-tumor immune response. In the present study, the serum obtained from the VPDT-cured mice was studied and found to possess various immunomodulatory properties. In in vitro studies, it stimulated cytokine secretions of IL-6 and C-X-C motif chemokine ligands 1-3 in CT26 cells through the NF-κB and MAPK pathways. The complement protein C5a boosted in the serum was shown to be involved in the process. The serum also induced calreticulin exposure on CT26 cells and activated dendritic cells. It contained CT26-targeting antibodies which, through the Fc region, induced macrophage engulfment of the tumor cells. In in vivo studies, inoculation of the serum-treated CT26 cells to mice demonstrated a retarded tumor growth with leukocytes, particularly T cells, attracted to the tumor site. In addition, the VPDT-cured mice showed different degrees of resistance against challenge of other types of murine tumor cells, for example, the breast tumor 4T1 and EMT6 cells.

Immunogenic necroptosis in the anti-tumor photodynamic action of BAM-SiPc, a silicon(IV) phthalocyanine-based photosensitizer

Photodynamic therapy (PDT) is an anti-tumor modality which employs three individually non-toxic substances, including photosensitizer, light and oxygen, to produce a toxic effect. Besides causing damage to blood vessels that supply oxygen and nutrients to the tumor and killing the tumor by a direct cytotoxic effect, PDT has also been known to trigger an anti-tumor immune response. For instance, our previous study showed that PDT with BAM-SiPc, a silicon(IV) phthalocyanine based-photosensitizer, can not only eradicate the mouse CT26 tumor cells in a Balb/c mouse model, but also protect the mice against further re-challenge of the tumor cells through an immunomodulatory mechanism. To understand more about the immune effect, the biochemical actions of BAM-SiPc-PDT on CT26 cells were studied in the in vitro system. It was confirmed that the PDT treatment could induce immunogenic necroptosis in the tumor cells. Upon treatment, different damage-associated molecular patterns were exposed onto the cell surface or released from the cells. Among them, calreticulin was found to translocate to the cell membrane through a pathway similar to that in chemotherapy. The activation of immune response was also demonstrated by an increase in the expression of different chemokines.

Cadherin-17 Targeted Near-Infrared Photoimmunotherapy for Treatment of Gastrointestinal Cancer

In cancer photodynamic therapy (PDT), a photosensitizer taken up by cancer cells can generate reactive oxygen species upon near-infrared light activation to induce cancer cell death. To increase PDT potency and decrease its adverse effect, one approach is to conjugate the photosensitizer with an antibody that specifically targets cancer cells. In the present study, IR700, a hydrophilic phthalocyanine photosensitizer, was conjugated to the humanized monoclonal antibody ARB102, which binds specifically cadherin-17 (CDH17 aka CA17), a cell surface marker highly expressed in gastrointestinal cancer to produce ARB102-IR700. Photoimmunotherapy (PIT) of gastrointestinal cancer cell lines was conducted by ARB102-IR700 treatment and near-infrared light irradiation. The results showed that ARB102-IR700 PIT could induce cell death in CDH17-positive cancer cells with high potency. In a co-culture model, CDH17-negative and CDH17-overexpressing SW480 cells were labeled with distinct fluorescent dyes and cultured together prior to PIT treatment. The results confirmed that ARB102-IR700 PIT could kill CDH17-positive cells specifically, while leaving the adjacent CDH17-negative cells unaffected. An in vivo efficacy study was conducted using a pancreatic adenocarcinoma AsPC-1 xenograft tumor model in nude mice. Fluorescence scanning indicated that ARB102-IR700 accumulated specifically in the tumor sites. To perform PIT, at 24 and 48 h postinjection, mice were irradiated with a 680 nm laser at the tumor site to activate the photosensitizer. It was shown that ARB102-IR700 PIT could inhibit tumor growth significantly. In summary, this study demonstrated that the novel ARB102-IR700 is a promising agent for PIT in gastrointestinal cancers.

Conjugation of Phthalocyanine Photosensitizer with Poly(amidoamine) Dendrimer: Improved Solubility, Disaggregation and Photoactivity Against HepG2 Cells

OBJECTIVE

To improve solubility and to reduce aggregation, ZnPcC4 was conjugated to a third-generation poly-amidoamine dendrimer with amino end group (G3-PAMAM-NH2), which acts as a novel photodynamic therapy (PDT) drug carrier system.

METHODS

The phthalocyanines were synthesized by construction reaction. The nano drug was obtained from the conjugation of ZnPcC4 to G3-PAMAM-NH2, using EDC and NHS as coupling agents. The ZnPcC4@G3-PAMAM-NH2 conjugation was characterized by UV-Vis and MS. The 1O2 quantum yield of ZnPcC4@G3-PAMAM-NH2 in water was measured by the chemiluminescence method. The in vitro PDT responses of the studied photosensitizers were studied in hepatocellular carcinoma cell line HepG2 by MTT assay.

RESULTS

At ZnPcC4/G3-PAMAM-NH2 raw ratio of 100/1, the ZnPcC4 conjugate had improved solubility and reduced aggregation tendency in aqueous solution. At this optimum molar ratio, ZnPcC4- G3-PAMAM-NH2 inhibited HepG2 cells, with a half-maximal inhibitory concentration of 1.67 µg/mL upon infrared light exposure. The controls, including dark conditions, or media as well as G3-PAMAM-NH2 exposure, exhibited no inhibitory response.

CONCLUSION

The conjugation of phthalocyanine photosensitizer ZnPcC4 to poly-amidoamine dendrimer G3-PAMAM-NH2 improved the PDT outcomes, in which the optimized binding ratio of ZnPcC4 to G3-PAMAM-NH2 was 6:1.

Improved photodynamic anticancer activity and mechanisms of a promising zinc(II) phthalocyanine-quinoline conjugate photosensitizer in vitro and in vivo

Since the discovery of photodynamic therapy, scientists have constantly been searching for more effective and ideal photosensitizers (PSs). As part of our ongoing interest in the development of more potent photosensitizers, quinoline-8-yloxy-substituted zinc(II) phthalocyanine (ZnPc-Q1) has been identified as a promising photosensitizers in tumor cells. This study aims to explore the photodynamic mechanism and in vivo photodynamic efficacy of ZnPc-Q1, and further evaluate its potential in clinical photodynamic therapy application. The single crystal structure of ZnPc-Q1 enables the easy control of clinical quality standards. In comparison with Photofrin, ZnPc-Q1 exhibits considerably higher in vitro anticancer activity by dual dose-related mechanisms (antiproliferative and apoptosis). In addition, the in vivo results demonstrate that ZnPc-Q1 exhibits significant tumor regression with less skin photosensitivity by both direct killing and apoptosis anticancer mechanisms. In conclusion, ZnPc-Q1 can be considered to be a promising ideal PS for clinical application owing to its defined chemical structure without phthalocyanine isomerization, good absorption of tissue-penetrating red light, improved photodynamic therapy efficacy, and reduced skin phototoxicity.

Photodynamic therapy of pancreatic cancer: Where have we come from and where are we going?

Photodynamic therapy (PDT) is a potential adjuvant therapy in pancreatic cancer with several advantages. Mechanistically, pancreatic cancer PDT can induce apoptosis and necrosis of pancreatic cancer cells and lead to vascular damage and enhance anti-tumor immune response in tumor tissues. However, limitations of current photosensitizers such as limited penetration depth, poor targeted therapy and inadequate reactive oxygen species (ROS) generation still exist. Recently, several novel photosensitizers have been reported to break through limits in pancreatic cancer PDT. Methods combined with biomedical engineering, materialogy and chemical engineering have been employed to overcome the difficulties and to realize targeted therapy. Preclinical and clinical trials also preliminarily confirmed the technical feasibility and safety of pancreatic cancer PDT. Therefore, PDT may be potential to be used as an effective adjuvant therapy in pancreatic cancer multimodality therapy. This review will give an overview about pancreatic cancer PDT from basic experimental studies, preclinical and clinical application to future direction of pancreatic cancer PDT.

Tumor cell death in orthotopic breast cancer model by NanoALA: a novel perspective on photodynamic therapy in oncology

Aim: Nano-5-aminolevulic acid (NanoALA)-mediated photodynamic therapy (PDT), an oil-in-water polymeric nanoemulsion of ALA, was evaluated in a murine model of breast cancer. Materials & methods: Analysis of ALA-derived protoporphyrin IX production and acute toxicity test, biocompatibility and treatment efficacy, and long-term effect of NanoALA-PDT on tumor progression were performed. Results: The nanoformulation favored the prodrug uptake by tumor cells in a shorter time (1.5 h). As a result, the adverse effects were negligible and the response rates for primary mammary tumor control were significantly improved. Tumor progression was slower after NanoALA-PDT treatment, providing longer survival. Conclusion: NanoALA is a good proactive drug candidate for PDT against cancer potentially applied as adjuvant/neoadjuvant intervention strategy for breast cancer.

Immune Responses after Vascular Photodynamic Therapy with Redaporfin

Photodynamic therapy (PDT) relies on the administration of a photosensitizer (PS) that is activated, after a certain drug-to-light interval (DLI), by the irradiation of the target tumour with light of a specific wavelength absorbed by the PS. Typically, low light doses are insufficient to eradicate solid tumours and high fluence rates have been described as poorly immunogenic. However, previous work with mice bearing CT26 tumours demonstrated that vascular PDT with redaporfin, using a low light dose delivered at a high fluence rate, not only destroys the primary tumour but also reduces the formation of metastasis, thus suggesting anti-tumour immunity. This work characterizes immune responses triggered by redaporfin-PDT in mice bearing CT26 tumours. Our results demonstrate that vascular-PDT leads to a strong neutrophilia (2-24 h), systemic increase of IL-6 (24 h), increased percentage of CD4⁺ and CD8⁺ T cells producing IFN-γ or CD69⁺ (2-24 h) and increased CD4⁺/CD8⁺ T cell ratio (2-24 h). At the tumour bed, T cell tumour infiltration disappeared after PDT but reappeared with a much higher incidence one day later. In addition, it is shown that the therapeutic effect of redaporfin-PDT is highly dependent on neutrophils and CD8⁺ T cells but not on CD4⁺ T cells.

Recent advances in nanomaterial-based synergistic combination cancer immunotherapy

This review aims to summarize various synergistic combination cancer immunotherapy strategies based on nanomaterials.

Cancer-targeted reactive oxygen species-degradable polymer nanoparticles for near infrared light-induced drug release

Nanocarriers can be translocated to the peripheral region of tumor tissues through the well-known enhanced permeability and retention effects.

Fractional Laser Releases Tumor-Associated Antigens in Poorly Immunogenic Tumor and Induces Systemic Immunity

Currently ablative fractional photothermolysis (aFP) with CO₂ laser is used for a wide variety of dermatological indications. This study presents and discusses the utility of aFP for treating oncological indications. We used a fractional CO₂ laser and anti-PD-1 inhibitor to treat a tumor established unilaterally by the CT26 wild type (CT26WT) colon carcinoma cell line. Inoculated tumors grew significantly slower in aFP-treated groups (aFP and aFP + anti-PD-1 groups) and complete remission was observed in the aFP-treated groups. Flow cytometric analysis showed aFP treatment elicited an increase of CD3+, CD4+, CD8+ vand epitope specific CD8+ T cells. Moreover, the ratio of CD8+ T cells to Treg increased in the aFP-treated groups. Additionally, we established a bilateral CT26WT-inoculated mouse model, treating tumors on one-side and observing both tumors. Interestingly, tumors grew significantly slower in the aFP + anti-PD-1 groups and complete remission was observed for tumors on both aFP-treated and untreated sides. This study has demonstrated a potential role of aFP treatments in oncology.