Central serous chorioretinopathy (CSC) is a multifactorial disease of the retina and the choroid in the human eye. The disease is characterized by a serous detachment of the neurosensory retina in... Show moreCentral serous chorioretinopathy (CSC) is a multifactorial disease of the retina and the choroid in the human eye. The disease is characterized by a serous detachment of the neurosensory retina in the central macula, which causes visual complaints including blurred vision, a central relative scotoma, metamorphopsia, and alterations in color and contrast vision. Multimodal imaging techniques have revealed that abnormally thickened, leaking choroidal blood vessels cause an excessive fluid outflow into the interstitial space, which presumably causes the characteristic thickened choroid. This thesis addresses the clinical spectrum of CSC including the acute CSC, the chronic CSC and the severe chronic CSC. Here we suggest a strict but practical classification of CSC phenotypes based on findings on multimodal imaging techniques. We also report on the outcome of treatment, especially photodynamic therapy (PDT), in all phenotypes of CSC and provide recommendation regarding disease management and therapy. Furthermore, in this thesis we assess the roll of genetic variations among different phenotypes of CSC for a better understanding of the pathogenesis of the disease. Despite the genetic associations found in CSC phenotypes, we conclude that the so far known genetic variations do not explain the different clinical disease presentation of CSC phenotypes. Show less
This thesis provides novel insights in the capacity of photodynamic therapy (PDT) to disrupt the tumor and its vasculature for improved accumulation of nanosized drug carriers in the tumor.... Show moreThis thesis provides novel insights in the capacity of photodynamic therapy (PDT) to disrupt the tumor and its vasculature for improved accumulation of nanosized drug carriers in the tumor. Moreover, it has shown the importance of the origin and physiological state of extracellular vesicles used as carriers for photosensitizers. It has also expanded knowledge of PDT-induced immunogenic cell death through damage-associated molecular pattern exposure and release that can initiate specific antitumor immune responses. Furthermore, several chapters identify combinations of PDT and immunotherapy that improve the therapeutic efficacy compared to currently used treatment options. Future studies that further investigate ways to benefit from the immunostimulatory effects of PDT hold great promise and may introduce exciting new modalities for improved treatments of cancer. Show less
In this thesis, we start with a general introduction in Chapter 1 to briefly present the state of PDT, immune therapies, and nanotechnology in the field of cancer. PDT is a well-established... Show moreIn this thesis, we start with a general introduction in Chapter 1 to briefly present the state of PDT, immune therapies, and nanotechnology in the field of cancer. PDT is a well-established approach in superficial cancer treatment. The aim of my Ph.D. research work has been to improve therapeutic responses in solid tumors by novel combinatorial strategies based on PDT and the utilization of nanotechnology. Insights and concepts in these works are expected to help to design personalized therapeutic interventions in cancer progression. In Chapter 2, we focused on the combination of PDT with a stimulator of interferon genes (STING) agonist: ADU-S100. We investigated the anti-tumor efficiency and survival time after this combined treatment in colon tumor mice models. We found that ADU-S100 post-PDT treatment could enhance PDT-induced inflammation and immune responses, which lead to abscopal effects in a distal untreated tumor. The combination also protected cured mice from tumor recurrence through memory T cell anti-tumor immune responses with high probability. In Chapter 3, we found that PDT in combination with viral core particles could prime systematic immune responses and serum antibody intensity to against colon cancer process in MC38 tumor-bearing mice. In Chapter 4, we reviewed the current challenges facing the combination of PDT and multiple cancer treatment options based on current published literature. We highlighted the opportunities of nanoparticle-based PDT in cancer therapies. In Chapter 5, we investigated how hydrogel-supported near-infrared (NIR) -PDT with improved therapy potential in tumor-bearing mice by combining it with immune checkpoint inhibitors. In addition to the improved tumor growth inhibitory effects and prolonged survival time, immune mechanisms were also studied. We found that hydrogel-supported NIR-PDT by multi-stimulation could induce a higher level of lymphocytes in the circulating blood and increased lymphocytes infiltration into tumor site. A general discussion of overall data observed in this work, and clinical and research prospects related to this thesis are provided in Chapter 6. Show less
Purpose: Comparing anatomic and functional efficacy and safety of primary treatment with either half-dose photodynamic therapy (PDT) or oral eplerenone, or crossover treatment in chronic central... Show morePurpose: Comparing anatomic and functional efficacy and safety of primary treatment with either half-dose photodynamic therapy (PDT) or oral eplerenone, or crossover treatment in chronic central serous chorioretinopathy patients. Methods: After the SPECTRA trial baseline visit, patients were randomized to either half-dose PDT or eplerenone and received crossover treatment if persistent subretinal fluid (SRF) on optical coherence tomography (OCT) was present at first follow-up (at 3 months). Presence of SRF and best-corrected visual acuity (BCVA) was evaluated at 12 months. Results: Out of the 90 patients evaluated at 12 months, complete SRF resolution was present on OCT in 43/48 (89.6%) of patients who were primarily randomized to half-dose PDT and in 37/42 (88.1%) who were primarily randomized to eplerenone. Out of the 42 patients that were primarily randomized to eplerenone, 35 received crossover treatment with halfdose PDT. The BCVA improved significantly more at 12 months in patients who had received primary half-dose PDT as compared to the primary eplerenone group (p = 0.030). Conclusions: Twelve months after baseline visit, most patients treated with half-dose PDT (either primary or crossover treatment) still had complete SRF resolution. The long-term BCVA in patients who receive primary half-dose PDT is better than in patients in whom PDT is delayed due to initial eplerenone treatment with persistent SRF. Show less
Photodynamic therapy (PDT) has shown impressive therapeutic effects on various types of cancers by reactive oxygen species (ROS) generation and induction of immune responses. However, under certain... Show morePhotodynamic therapy (PDT) has shown impressive therapeutic effects on various types of cancers by reactive oxygen species (ROS) generation and induction of immune responses. However, under certain conditions, the immune responses induced by PDT are not always sufficient to eradicate the remaining tumor cells. On the other hand, the photosensitizer indocyanine green (ICG) can mediate PDT under near-infrared (NIR) illumination, thereby enhancing the penetration depth of the excitation light into the tumor. We found that ICG is rapidly taken up in vitro by colorectal MC38 and CT26 tumor cells and it promotes PDT-mediated cell-killing effects. Our results furthermore revealed that ICG induces immunogenic cell death (ICD), as dendritic cells (DCs) were found to engulf ICG-PDT-treated tumor cells and undergo phenotypic maturation. ICG accumulated in tumors 2 h after administration, as measured by fluorescence and photoacoustic imaging. Considering the advantages of ICG as a photosensitizer, we sought to design a therapy that combines PDT and immune checkpoint blockade to maximize tumor control. To this end, a 25% thermosensitive polymer 407 hydrogel was included as a co-delivery platform for this treatment scheme. NIR-PDT under 808 nm irradiation in combination with cytotoxic T-lymphocyte-associated protein 4 (CTLA4)/programmed death-ligand 1 (PD-L1) checkpoint blockade prolonged survival rate of colorectal tumor-bearing mice by inducing a series of immune responses, like the phagocytosis of tumor debris by macrophages and DCs, and induction of acute inflammation, leukocyte infiltration, maturation and activation of DCs. Altogether, our work presents a NIR-triggered PDT strategy in combination with immune checkpoint blockade. Compared to a single treatment, the combination treatment increased efficiency to inhibit solid tumor growth and improved the survival rate of tumor-bearing mice. Show less
Extracellular vesicles (EVs) are promising drug carriers of photosensitizers for photodynamic therapy (PDT) in cancer treatment, due to their ability to circulate in blood and enter cells... Show moreExtracellular vesicles (EVs) are promising drug carriers of photosensitizers for photodynamic therapy (PDT) in cancer treatment, due to their ability to circulate in blood and enter cells efficiently. The therapeutic potential of EVs has been suggested to depend on the type and physiological state of their cell of origin. However, the effects of deriving EVs from various cells in different physiological states on their antitumor capacity are rarely evaluated. In the present study, we compared the antitumor efficacy of EV-mediated PDT by incorporating the photosensitizer Zinc Phthalocyanine (ZnPc) into EVs from multiple cells sources. ZnPc was incorporated by a direct incubation strategy into EVs derived from immune cells (M1-like macrophages and M2-like macrophages), cancer cells (B16F10 melanoma cancer cells) and external sources (milk). Our data show that all EVs are suitable carriers for ZnPc and enable efficient PDT in vitro in co-culture models and in vivo. We observed that EV-mediated PDT initiates immunogenic cell death through the release and exposure of damage associated molecular patterns (DAMPs) on cancer cells, which subsequently induced dendritic cell (DC) maturation. Importantly, of all ZnPc-EVs tested, in absence of light only M1-ZnPc displayed toxicity to MC38, but not to DC, in monoculture and in co-culture, indicating specificity for cancer over immune cells. In MC38 tumor-bearing mice, only M1-ZnPc induced a tumor growth delay compared to control in absence of light. Interestingly, M1- but not M2-mediated PDT, induced complete responses against MC38 tumors in murine models (100% versus 38% of cases, respectively), with survival of all animals up to at least 60 days post inoculation. Finally, we show that all cured animals are protected from a rechallenge with MC38 cells, suggesting the induction of immunological memory after EV-mediated PDT. Together, our data show the importance of the cell type from which the EVs are obtained and highlight the impact of the immunological state of these cells on the antitumor efficacy of EV-mediated PDT. Show less
This thesis involves the eye disease central serous chorioretinopathy. This disease is characterized by an accumulation of subretinal fluid, which can lead to a reduction in vision, changes in... Show moreThis thesis involves the eye disease central serous chorioretinopathy. This disease is characterized by an accumulation of subretinal fluid, which can lead to a reduction in vision, changes in contrast vision and sometimes distortions in the visual field. Central serous chorioretinopathy mainly occurs in men between 40 and 50 years old. In case of prolonged persistence of subretinal fluid, irreversible vision loss may occur. The most common treatments are photodynamic therapy, eplerenone, and micropulse laser, but there is no consensus on the best treatment. The research in this thesis evaluates the effects and comparisons of photodynamic therapy with micropulse laser and also compared to eplerenone. Patients were enrolled in prospective studies and differences in outcomes (including vision, contrast vision) between the treated groups were evaluated. The results of these studies allow us to improve patient counseling and also to provide the right treatment. The studies presented in this thesis, combined with the available scientific literature, indicate that half-dose therapy is currently the preferred option for the treatment of central serous chorioretinopathy. Show less
In this thesis, the effects of a new form of immunotherapy was investigated and studied how it can be used against different types of cancers. The investigated immunotherapy is based on injecting... Show moreIn this thesis, the effects of a new form of immunotherapy was investigated and studied how it can be used against different types of cancers. The investigated immunotherapy is based on injecting nanoparticles loaded with various immunologically active molecules (immunomodulatory nanoparticles) that can modulate the immune system to attack cancer cells more efficiently. The effectiveness of this immunomodulatory nanoparticles have been studied on different mouse cancer models and investigated as a single treatment or in combination with other known therapies, such as chemotherapy, therapeutic cancer vaccination, or photodynamic therapy. Show less
In this thesis, the researcher developed a nanosystem based on the metallophilic Interaction between cyclometalated complexes. Using this strategy, the researcher achieved efficient photodynamic... Show moreIn this thesis, the researcher developed a nanosystem based on the metallophilic Interaction between cyclometalated complexes. Using this strategy, the researcher achieved efficient photodynamic therapy to several cancers, accompanied by the cell imaging property. Show less
Purpose To evaluate the clinical outcomes after half-dose photodynamic therapy (PDT) in chronic central serous chorioretinopathy (cCSC) patients with pre-existent fovea-involving atrophy. Methods... Show morePurpose To evaluate the clinical outcomes after half-dose photodynamic therapy (PDT) in chronic central serous chorioretinopathy (cCSC) patients with pre-existent fovea-involving atrophy. Methods In this retrospective study, cCSC patients who had a window defect of the retinal pigment epithelium (RPE) on fluorescein angiography (FA), compatible with RPE atrophy, prior to half-dose PDT were included. Results Thirty-four cCSC eyes with typical findings of cCSC on multimodal imaging, and fovea-involving RPE atrophy on FA, were included. At the first visit after PDT (at a median of 1.8 months after half-dose PDT), 20 eyes (59%) had a complete resolution of SRF (p < 0.001), while this was the case in 19 eyes (56%) at final visit (median of 11.3 months after half-dose PDT; p < 0.001). The mean BCVA in Early Treatment of Diabetic Retinopathy Study letters was 71. 2 +/- 15.9 at last visit before PDT, which increased to 74.1 +/- 14.1 at first visit after PDT (p = 0.093, compared with baseline), and changed to 73.0 +/- 19.1 at final visit (p = 0.392, compared with baseline). Both at first visit after PDT and at final visit, a significant decrease in subfoveal choroidal thickness was observed (p = 0.032 and p = 0.004, respectively). Conclusions Half-dose PDT in cCSC patients with pre-existing fovea-involving atrophy may lead to anatomical changes, but not to functional improvements. Ideally, cCSC should be treated with half-dose PDT before the occurrence of such atrophy. Show less
In this thesis, we will utilize embryonic zebrafish tumour models to understand the interaction between engrafted human cancer cells and macrophages from the host, test drug administration... Show moreIn this thesis, we will utilize embryonic zebrafish tumour models to understand the interaction between engrafted human cancer cells and macrophages from the host, test drug administration modalities and anti-cancer efficacies of newly-developed PDT and PACT compounds, and test a light-triggered liposomal system for targeted drug delivery specifically to cancer cells in vivo. In chapter 2, we investigate the role of macrophages in tumour-induced angiogenesis. We show that macrophage-dependent angiogenesis is driven by macrophage recruitment to lactic acid secreted by glycolytic B16 melanoma cells. Chemical inhibition of macrophages and glycolysis blocks the initiation of angiogenesis in these models, suggesting that macrophages attracted to glycolytic melanoma cells contribute to the tumour-induced angiogenesis process.In chapters 3 and 4, we explore novel PDT and PACT compounds, respectively, for treatment of conjunctival melanoma in zebrafish. We inject conjunctival melanoma cells into the retro-orbital site to establish an orthotopic model and into the Duct of Cuvier to generate an ectopic model. Our results prove that zebrafish provides a fast vertebrate cancer model to test the optimal administration regimen of drugs, conditions of light irradiation, host toxicity and anti-cancer efficacy of PDT and PACT drugs against conjunctival melanoma.In chapter 5, we focus on modifying liposomes to be light triggered in order to deliver drugs specifically to cancer cells. We inject MDA231 breast cancer cells into the Duct of Cuvier at 2 days post fertilization (dpf) to initiate metastasis to the CHT. We successfully demonstrate that light-triggered, cell-specific delivery of liposome-encapsulated doxorubicin reduces the xenograft cancer cell burden without enhanced cytotoxicity of the zebrafish embryos. In chapter 6, we summarize the novel anti-cancer strategies, which we have developed using zebrafish xenograft models. In the same chapter, we frame our findings in the current scientific landscape and discuss future perspectives. Show less
Rijssen, T.J. van; Singh, S.R.; Dijk, E.H.C. van; Rasheed, M.A.; Vupparaboina, K.K.; Boon, C.J.F.; Chhablani, J. 2020
Purpose To assess whether treatment of chronic central serous chorioretinopathy (cCSC) with photodynamic therapy (PDT) and high-density subthreshold micropulse laser (HSML) results in choroidal... Show morePurpose To assess whether treatment of chronic central serous chorioretinopathy (cCSC) with photodynamic therapy (PDT) and high-density subthreshold micropulse laser (HSML) results in choroidal vascularity index (CVI) changes that may account for the treatment effect. Methods Patients with cCSC were prospectively included and analyzed. Patients received either half-dose PDT or HSML treatment. CVI of the affected and unaffected eye was obtained before treatment, 6 to 8 weeks after treatment, and 7 to 8 months after treatment. Results At baseline, 29 eyes (29 patients) were included both in the PDT and in the HSML group. The mean (+/- standard deviation) CVI change in the HSML group between before PDT and 6 to 8 weeks after PDT was - 0.009 +/- 0.032 (p = 0.127), whereas this was 0.0025 +/- 0.037 (p = 0.723) between the visit before PDT and final visit. The patients in the PDT group had a CVI change of - 0.0025 +/- 0.037 (p = 0.723) between the visit before PDT and first visit after PDT, and a mean CVI change of - 0.013 +/- 0.038 (p = 0.080) between the visit before PDT and final visit. There was no significant correlation between CVI and BCVA at the measured time points, in both the HSML group (p = 0.885), and in the PDT group (p = 0.904). Moreover, no significant changes in CVI occurred in the unaffected eye at any time point. Conclusions PDT and HSML do not significantly affect CVI, and therefore a CVI change may not be primarily responsible for the treatment effect. The positive treatment effect of both interventions may rely on other mechanisms, such as an effect on choriocapillaris and/or retinal pigment epithelium function. Show less
Photodynamic therapy (PDT) using verteporfin (Visudyne (R); Bausch + Lomb) is a treatment that is widely used to elicit cell and tissue death. In ophthalmology, PDT targets choroidal vascular... Show morePhotodynamic therapy (PDT) using verteporfin (Visudyne (R); Bausch + Lomb) is a treatment that is widely used to elicit cell and tissue death. In ophthalmology, PDT targets choroidal vascular abnormalities and induces selective occlusion of vessels. PDT was originally used in combination with full-dose verteporfin to treat neovascular age-related macular degeneration. Since the introduction of treatment with vascular endothelial growth factor receptor inhibitors, the clinical targets of PDT have shifted to other chorioretinal conditions, such as central serous chorioretinopathy, polypoidal choroidal vasculopathy, and choroidal hemangioma. In recent years, clinical studies have facilitated the optimization of treatment outcomes through changes in protocols, including the introduction of reduced treatment settings, such as PDT with half-dose verteporfin and half-fluence PDT. Here, we review PDT and its use for chorioretinal diseases from a practical perspective. Show less
In cancer treatment, nanomedicines may be employed in an attempt to improve the tumor localization of antineoplastic drugs e.g. immunotherapeutic agents either through passive or active targeting,... Show moreIn cancer treatment, nanomedicines may be employed in an attempt to improve the tumor localization of antineoplastic drugs e.g. immunotherapeutic agents either through passive or active targeting, thereby potentially enhancing therapeutic effect and reducing undesired off-target effects. However, a large number of administrated nanocarriers often fail to reach the tumor area. In the present study, we show that photodynamic therapy (PDT) enhances the tumor accumulation of systemically administered lipid-PEG layer coated poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NP). Intravital microscopy and histological analysis of the tumor area reveal that the tumor vasculature was disrupted after PDT, disturbing blood flow and coinciding with entrapment of nanocarriers in the tumor area. We observed that the nanoparticles accumulating after treatment do not confine to specific locations within the tumor, but rather localize to various cells present throughout the tumor area. Finally, we show by flow cytometry that NP accumulation occurred mostly in immune cells of the myeloid lineage present in the tumor microenvironment (TME) as well as in tumor cells, albeit to a lower extent. These data expose opportunities for combination treatments of clinical PDT with NP-based immunotherapy to modulate the TME and improve antitumor immune responses. Show less
Targeted photodynamic therapy (PDT) has the potential to selectively damage tumor tissue and to increase tumor vessel permeability. Here we characterize the tissue biodistribution of two EGFR... Show moreTargeted photodynamic therapy (PDT) has the potential to selectively damage tumor tissue and to increase tumor vessel permeability. Here we characterize the tissue biodistribution of two EGFR-targeted nanobody-photosensitizer conjugates (NB-PS), the monovalent 7D12-PS and the biparatopic 7D12-9G8-PS. In addition, we report on the local and acute phototoxic effects triggered by illumination of these NB-PS which have previously shown to lead to extensive tumor damage.Methods: Intravital microscopy and the skin-fold chamber model, containing OSC-19-luc2-cGFP tumors, were used to investigate: a) the fluorescence kinetics and distribution, b) the vascular response and c) the induction of necrosis after illumination at 1 or 24 h post administration of 7D12-PS and 7D12-9G8-PS. In addition, dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) of a solid tumor model was used to investigate the microvascular status 2 h after 7D12-PS mediated PDT.Results: Image analysis showed significant tumor colocalization for both NB-PS which was higher for 7D12-9G8-PS. Intravital imaging showed clear tumor cell membrane localization 1 and 2 h after administration of 7D12-9G8-PS, and fluorescence in or close to endothelial cells in normal tissue for both NB-PS. PDT lead to vasoconstriction and leakage of tumor and normal tissue vessels in the skin-fold chamber model. DCE-MRI confirmed the reduction of tumor perfusion after 7D12-PS mediated PDT. PDT induced extensive tumor necrosis and moderate normal tissue damage, which was similar for both NB-PS conjugates. This was significantly reduced when illumination was performed at 24 h compared to 1 h after administration.Discussion: Although differences were observed in distribution of the two NB-PS conjugates, both led to similar necrosis. Clearly, the response to PDT using NB-PS conjugates is the result of a complex mixture of tumor cell responses and vascular effects, which is likely to be necessary for a maximally effective treatment. Show less
The aim of this thesis is to increase the understanding of genetic and clinical aspects of central serous chorioretinopathy, a common and mysterious chorioretinal disease. Moreover, more... Show moreThe aim of this thesis is to increase the understanding of genetic and clinical aspects of central serous chorioretinopathy, a common and mysterious chorioretinal disease. Moreover, more insight into the optimal treatment for central serous chorioretinopathy is provided, since this thesis includes the first randomised controlled trial assessing the outcome of half-dose photodynamic therapy and high-density subthreshold micropulse laser treatment. As central serous chorioretinopathy mainly occurs in middle-aged professionally active patients, and can lead to progressive decline in visual acuity and vision-related quality of life, gaining knowledge on the disease and its treatment is of great importance. Show less
