Photochemical delivery of bleomycin induces T-cell activation of importance for curative effect and systemic anti-tumor immunity

Cellular Imaging and Time-Domain FLIM Studies of Meso-Tetraphenylporphine Disulfonate as a Photosensitising Agent in 2D and 3D Models

Fluorescence lifetime imaging (FLIM) and confocal fluorescence studies of a porphyrin-based photosensitiser (meso-tetraphenylporphine disulfonate: TPPS2a) were evaluated in 2D monolayer cultures and 3D compressed collagen constructs of a human ovarian cancer cell line (HEY). TPPS2a is known to be an effective model photosensitiser for both Photodynamic Therapy (PDT) and Photochemical Internalisation (PCI). This microspectrofluorimetric study aimed firstly to investigate the uptake and subcellular localisation of TPPS2a, and evaluate the photo-oxidative mechanism using reactive oxygen species (ROS) and lipid peroxidation probes combined with appropriate ROS scavengers. Light-induced intracellular redistribution of TPPS2a was observed, consistent with rupture of endolysosomes where the porphyrin localises. Using the same range of light doses, time-lapse confocal imaging permitted observation of PDT-induced generation of ROS in both 2D and 3D cancer models using fluorescence-based ROS together with specific ROS inhibitors. In addition, the use of red light excitation of the photosensitiser to minimise auto-oxidation of the probes was investigated. In the second part of the study, the photophysical properties of TPPS2a in cells were studied using a time-domain FLIM system with time-correlated single photon counting detection. Owing to the high sensitivity and spatial resolution of this system, we acquired FLIM images that enabled the fluorescence lifetime determination of the porphyrin within the endolysosomal vesicles. Changes in the lifetime dynamics upon prolonged illumination were revealed as the vesicles degraded within the cells.

Proteomic analysis reveals mechanisms underlying increased efficacy of bleomycin by photochemical internalization in bladder cancer cells

Photochemical internalization (PCI) is a promising new technology for site-specific drug delivery, developed from photodynamic therapy (PDT). In PCI, light-induced activation of a photosensitizer trapped inside endosomes together with e.g. chemotherapeutics, nucleic acids or immunotoxins, allows cytosolic delivery and enhanced local therapeutic effect. Here we have evaluated the photosensitizer meso-tetraphenyl chlorine disulphonate (TPCS2a/fimaporfin) in a proteome analysis of AY-27 rat bladder cancer cells in combination with the chemotherapeutic drug bleomycin (BML). We find that BLMPCI attenuates oxidative stress responses induced by BLM alone, while concomitantly increasing transcriptional repression and DNA damage responses. BLMPCI also mediates downregulation of bleomycin hydrolase (Blmh), which is responsible for cellular degradation of BLM, as well as several factors known to be involved in fibrotic responses. PCI-mediated delivery might thus allow reduced dosage of BLM and alleviate unwanted side effects from treatment, including pulmonary fibrosis.

Photochemical Internalization with Fimaporfin: Enhanced Bleomycin Treatment for Head and Neck Cancer

Head and neck squamous cell carcinoma (HNSCC) still represents the world's sixth most common tumor entity, with increasing incidence. The reachability of light makes HNSCC suitable for light-based therapies such as Photochemical Internalization (PCI). The drug Bleomycin is cytotoxic and used as an anti-tumor medication. Since Bleomycin is endocytosed as a relatively large molecule, part of it is degraded in lysosomes before reaching its intracellular target. The goal of our study was to improve the intracellular availability of Bleomycin with PCI. We investigate the intracellular delivery of Bleomycin after PCI with the photosensitizer Fimaporfin. A systematic variation of Bleomycin and Fimaporfin concentrations and light irradiation led to the pronounced cell death of HNSCC cells. After optimization, the same level of tumor cell death of 75% was reached with a 20-fold lower Bleomycin concentration. This would allow treatment of HNSCC with high local tumor cell death and reduce the side effects of Bleomycin, e.g., lung fibrosis, at the same time. This demonstrates the increased efficacy of the anti-tumor medication Bleomycin in combination with PCI.

Near-infrared light-triggered nano-prodrug for cancer gas therapy

Gas therapy (GT) has attracted increasing attention in recent years as a new cancer treatment method with favorable therapeutic efficacy and reduced side effects. Several gas molecules, such as nitric oxide (NO), carbon monoxide (CO), hydrogen (H2), hydrogen sulfide (H2S) and sulfur dioxide (SO2), have been employed to treat cancers by directly killing tumor cells, enhancing drug accumulation in tumors or sensitizing tumor cells to chemotherapy, photodynamic therapy or radiotherapy. Despite the great progress of gas therapy, most gas molecules are prone to nonspecific distribution when administered systemically, resulting in strong toxicity to normal tissues. Therefore, how to deliver and release gas molecules to targeted tissues on demand is the main issue to be considered before clinical applications of gas therapy. As a specific and noninvasive stimulus with deep penetration, near-infrared (NIR) light has been widely used to trigger the cleavage and release of gas from nano-prodrugs via photothermal or photodynamic effects, achieving the on-demand release of gas molecules with high controllability. In this review, we will summarize the recent progress in cancer gas therapy triggered by NIR light. Furthermore, the prospects and challenges in this field are presented, with the hope for ongoing development.

Light-controlled elimination of PD-L1+ cells

The programmed death ligand-1 (PD-L1), also known as CD274 or B7-H1, is mainly expressed on cancer cells and/or immunosuppressive cells in the tumor microenvironment (TME) and plays an essential role in tumor progression and immune escape. Immune checkpoint inhibitors (ICIs) of the PD-1/PD-L1 axis have shown impressive clinical success, however, the majority of the patients do not respond to immune checkpoint therapy (ICT). Thus, to overcome ICT resistance there is a high need for potent and novel strategies that simultaneously target both tumor cells and immunosuppressive cells in the TME. In this study, we show that the intracellular light-controlled drug delivery method photochemical internalization (PCI) induce specific and strongly enhanced cytotoxic effects of the PD-L1-targeting immunotoxin, anti-PD-L1-saporin (Anti-PDL1-SAP), in the PD-L1+ triple-negative breast cancer MDA-MB-231 cell line, while no enhanced efficacy was obtained in the PD-L1 negative control cell line MDA-MB-453. Using fluorescence microscopy, we reveal that the anti-PD-L1 antibody binds to PD-L1 on the surface of the MDA-MD-231 cells and overnight accumulates in late endosomes and lysosomes where it co-localizes with the PCI photosensitizer fimaporfin (TPCS_2a). Moreover, light-controlled endosomal/lysosomal escape of the anti-PD-L1 antibody and fimaporfin into the cytosol was obtained. We also confirm that the breast MDA-MB-468 and the prostate PC-3 and DU-145 cancer cell lines have subpopulations with PD-L1 expression. In addition, we show that interferon-gamma strongly induce PD-L1 expression in the per se PD-L1 negative CT26.WT cells and enhance the PD-L1 expression in MC-38 cells, of which both are murine colon cancer cell lines. In conclusion, our work provides an in vitro proof-of-concept of PCI-enhanced targeting and eradication of PD-L1 positive immunosuppressive cells. This light-controlled combinatorial strategy has a potential to advance cancer immunotherapy and should be explored in preclinical studies.

The Multifaceted Roles of Copper in Cancer: A Trace Metal Element with Dysregulated Metabolism, but Also a Target or a Bullet for Therapy

In the human body, copper (Cu) is a major and essential player in a large number of cellular mechanisms and signaling pathways. The involvement of Cu in oxidation-reduction reactions requires close regulation of copper metabolism in order to avoid toxic effects. In many types of cancer, variations in copper protein levels have been demonstrated. These variations result in increased concentrations of intratumoral Cu and alterations in the systemic distribution of copper. Such alterations in Cu homeostasis may promote tumor growth or invasiveness or may even confer resistance to treatments. Once characterized, the dysregulated Cu metabolism is pinpointing several promising biomarkers for clinical use with prognostic or predictive capabilities. The altered Cu metabolism in cancer cells and the different responses of tumor cells to Cu are strongly supporting the development of treatments to disrupt, deplete, or increase Cu levels in tumors. The metallic nature of Cu as a chemical element is key for the development of anticancer agents via the synthesis of nanoparticles or copper-based complexes with antineoplastic properties for therapy. Finally, some of these new therapeutic strategies such as chelators or ionophores have shown promising results in a preclinical setting, and others are already in the clinic.

Photochemical Internalization for Intracellular Drug Delivery. From Basic Mechanisms to Clinical Research

Photochemical internalisation (PCI) is a unique intervention which involves the release of endocytosed macromolecules into the cytoplasmic matrix. PCI is based on the use of photosensitizers placed in endocytic vesicles that, following light activation, lead to rupture of the endocytic vesicles and the release of the macromolecules into the cytoplasmic matrix. This technology has been shown to improve the biological activity of a number of macromolecules that do not readily penetrate the plasma membrane, including type I ribosome-inactivating proteins (RIPs), gene-encoding plasmids, adenovirus and oligonucleotides and certain chemotherapeutics, such as bleomycin. This new intervention has also been found appealing for intracellular delivery of drugs incorporated into nanocarriers and for cancer vaccination. PCI is currently being evaluated in clinical trials. Data from the first-in-human phase I clinical trial as well as an update on the development of the PCI technology towards clinical practice is presented here.

Photochemically-Induced Release of Lysosomal Sequestered Sunitinib: Obstacles for Therapeutic Efficacy

Lysosomal accumulation of sunitinib has been suggested as an underlying mechanism of resistance. Here, we investigated if photochemical internalization (PCI), a technology for cytosolic release of drugs entrapped in endosomes and lysosomes, would activate lysosomal sequestered sunitinib. By super-resolution fluorescence microscopy, sunitinib was found to accumulate in the membrane of endo/lysosomal compartments together with the photosensitizer disulfonated tetraphenylchlorin (TPCS_2a). Furthermore, the treatment effect was potentiated by PCI in the human HT-29 and the mouse CT26.WT colon cancer cell lines. The cytotoxic outcome of sunitinib-PCI was, however, highly dependent on the treatment protocol. Thus, neoadjuvant PCI inhibited lysosomal accumulation of sunitinib. PCI also inhibited lysosomal sequestering of sunitinib in HT29/SR cells with acquired sunitinib resistance, but did not reverse the resistance. The mechanism of acquired sunitinib resistance in HT29/SR cells was therefore not related to lysosomal sequestering. Sunitinib-PCI was further evaluated on HT-29 xenografts in athymic mice, but was found to induce only a minor effect on tumor growth delay. In immunocompetent mice sunitinib-PCI enhanced areas of treatment-induced necrosis compared to the monotherapy groups. However, the tumor growth was not delayed, and decreased infiltration of CD3-positive T cells was indicated as a possible mechanism behind the failed overall response.

Photochemical Internalization: Light Paves Way for New Cancer Chemotherapies and Vaccines

Photochemical internalization (PCI) is a further development of photodynamic therapy (PDT). In this report, we describe PCI as a potential tool for cellular internalization of chemotherapeutic agents or antigens and systematically review the ongoing research. Eighteen published papers described the pre-clinical and clinical developments of PCI-mediated delivery of chemotherapeutic agents or antigens. The studies were screened against pre-defined eligibility criteria. Pre-clinical studies suggest that PCI can be effectively used to deliver chemotherapeutic agents to the cytosol of tumor cells and, thereby, improve treatment efficacy. One Phase-I clinical trial has been conducted, and it demonstrated that PCI-mediated bleomycin treatment was safe and identified tolerable doses of the photosensitizer disulfonated tetraphenyl chlorin (TPCS_2a). Likewise, PCI was pre-clinically shown to mediate major histocompatibility complex (MHC) class I antigen presentation and generation of tumor-specific cytotoxic CD8+ T-lymphocytes (CTL) and cancer remission. A first clinical Phase I trial with the photosensitizer TPCS_2a combined with human papilloma virus antigen (HPV) was recently completed and results are expected in 2020. Hence, photosensitizers and light can be used to mediate cytosolic delivery of endocytosed chemotherapeutics or antigens. While the therapeutic potential in cancer has been clearly demonstrated pre-clinically, further clinical trials are needed to reveal the true translational potential of PCI in humans.

Emodin sensitizes human pancreatic cancer cells to EGFR inhibitor through suppressing Stat3 signaling pathway

Background

Excessive expression of EGFR is closely related to tumor formation, transfer and deterioration, which has attracted much attention. EGFR overexpression may be detected in up to 90% of pancreatic tumors. However, drug resistance of EGFR inhibitors targeting treatment severely limits its clinical application.

Methods

In this study, Western blotting was used to detect the expression of p-Stat3, EGFR, Bcl-2, cleaved-caspase3 and Bax. Cell apoptosis was evaluated via flow cytometry. The colon assay and MTT assay were applied for detecting the cell proliferation in vitro. The xenograft mouse model was used to examine the cell proliferation in vivo.

Results

Emodin remarkably enhanced the anti-cancer effect of EGFR inhibitor on pancreatic cancer cells. In addition, emodin promoted afatinib-induced apoptosis by inhibiting the Stat3 signaling pathway. Meanwhile, siRNAs against Stat3 significantly increased the apoptosis of pancreatic cancer cells. EGFR inhibitor promoted phosphorylation of Stat3 in pancreatic cancer cells. Interestingly, emodin combined with EGFR inhibitor inhibited the proliferation of pancreatic cancer cells in vitro. The tumor xenograft mice model was further confirmed that emodin possessed a synergy anticancer effect with afatinib on pancreatic cancer cells by regulating the Stat3 expression.

Conclusion

These results indicate that the combination of emodin with EGFR inhibitor is an effective therapeutic strategy to sensitize human pancreatic cancer.

Iron and Copper Intracellular Chelation as an Anticancer Drug Strategy

A very promising direction in the development of anticancer drugs is inhibiting the molecular pathways that keep cancer cells alive and able to metastasize. Copper and iron are two essential metals that play significant roles in the rapid proliferation of cancer cells and several chelators have been studied to suppress the bioavailability of these metals in the cells. This review discusses the major contributions that Cu and Fe play in the progression and spreading of cancer and evaluates select Cu and Fe chelators that demonstrate great promise as anticancer drugs. Efforts to improve the cellular delivery, efficacy, and tumor responsiveness of these chelators are also presented including a transmetallation strategy for dual targeting of Cu and Fe. To elucidate the effectiveness and specificity of Cu and Fe chelators for treating cancer, analytical tools are described for measuring Cu and Fe levels and for tracking the metals in cells, tissue, and the body.

Iron and Copper Intracellular Chelation as an Anticancer Drug Strategy

A very promising direction in the development of anticancer drugs is inhibiting the molecular pathways that keep cancer cells alive and able to metastasize. Copper and iron are two essential metals that play significant roles in the rapid proliferation of cancer cells and several chelators have been studied to suppress the bioavailability of these metals in the cells. This review discusses the major contributions that Cu and Fe play in the progression and spreading of cancer and evaluates select Cu and Fe chelators that demonstrate great promise as anticancer drugs. Efforts to improve the cellular delivery, efficacy, and tumor responsiveness of these chelators are also presented including a transmetallation strategy for dual targeting of Cu and Fe. To elucidate the effectiveness and specificity of Cu and Fe chelators for treating cancer, analytical tools are described for measuring Cu and Fe levels and for tracking the metals in cells, tissue, and the body.

Light-enhanced VEGF121/rGel: A tumor targeted modality with vascular and immune-mediated efficacy

Interactions between stromal cells and tumor cells pay a major role in cancer growth and progression. This is reflected in the composition of anticancer drugs which includes compounds directed towards the immune system and tumor-vasculature in addition to drugs aimed at the cancer cells themselves. Drug-based treatment regimens are currently designed to include compounds targeting the tumor stroma in addition to the cancer cells. Treatment limiting adverse effects remains, however, one of the major challenges for drug-based therapy and novel tolerable treatment modalities with diverse high efficacy on both tumor cells and stroma is therefore of high interest. It was hypothesized that the vascular targeted fusion toxin VEGF₁₂₁/rGel in combination with the intracellular drug delivery technology photochemical internalization (PCI) stimulate direct cancer parenchymal cell death in addition to inhibition of tumor perfusion, and that an immune mediated response is relevant for treatment outcome. The aim of the present study was therefore to elucidate the anticancer mechanisms of VEGF₁₂₁/rGel-PCI. In contrast to VEGF₁₂₁/rGel monotherapy, VEGF₁₂₁/rGel-PCI was found to mediate its effect through VEGFR1 and VEGFR2, and a targeted treatment effect was shown on two VEGFR1 expressing cancer cell lines. A cancer parenchymal treatment effect was further indicated on H&E stains of CT26-CL25 and 4 T1 tumors. VEGF₁₂₁/rGel-PCI was shown, by dynamic contrast enhanced MRI, to induce a sustained inhibition of tumor perfusion in both tumor models. A 50% complete remission (CR) of CT26.CL25 colon carcinoma allografts was found in immunocompetent mice while no CR was detected in CT26.CL25 bearing athymic mice. In conclusion, the present report indicate VEGF₁₂₁/rGel -PCI as a treatment modality with multimodal tumor targeted efficacy that should be further developed towards clinical utilization.

Photodynamic therapy mediated immune therapy of brain tumors

Photodynamic therapy of tumors requires the topical, systemic or oral administration of a photosensitizing compound, illumination of the tumor area by light of a specific wavelength and the presence of oxygen. Light activation of the photosensitizer transfers energy to molecular oxygen creating singlet oxygen, a highly reactive and toxic species that rapidly reacts with cellular components causing oxidative damage, ultimately leading to cell death. Tumor destruction caused by photodynamic therapy is not only a result of direct tumor cell toxicity via the generation of reactive oxygen species but there is also an immunological and vascular component involved. The immune response to photodynamic therapy has been demonstrated to significantly enhance its efficacy. Depending on a number of factors, including type of photosensitizer, light dose and dose rate, photodynamic therapy has been shown to induce cell death via apoptosis, necrosis, autophagy and in particular immunogenic cell death. It is the purpose of this review to focus mainly on the role photodynamic therapy could play in the generation of specific anti-tumor immunity and vaccines for the treatment of brain tumors.

Self-assembled organic nanorods for dual chemo-photodynamic therapies

Photodynamic therapy (PDT) and chemotherapy have been extensively developed as effective approaches against cancer. Herein, we constructed organic nanorods by rational co-assembly of photosensitizer, di-iodinated borondipyrromethene (BDP-I2), and chemical anticancer drug, paclitaxel (PTX). The physico- and photochemical properties of the obtained nanorods were carefully investigated. BDP-I2 was selected for its high singlet oxygen (1O2) quantum yields. And the corresponding 1O2 generation ability and photodynamic effect were evaluated both in vitro and in vivo. The accelerated endosomal escape of the nanorods induced by the photodynamic effect enhanced the chemotherapeutic efficacy of PTX. We believe that this synergetic nanomedicine represents a new development for antitumor chemophotodynamic therapy.