Antibody-functionalized theranostic protein nanoparticles for the synergistic deep red fluorescence imaging and multimodal therapy of ovarian cancer

Among women, ovarian cancer is the fifth most frequent type of cancer, and despite benefiting from current standard treatment plans, 90% of patients relapse in the subsequent 18 months and, eventually, perish. As a result, via embracing nanotechnological advancements in the field of medical science, researchers working in the areas of cancer therapy and imaging are looking for the next breakthrough treatment strategy to ensure lower cancer recurrence rates and improved outcomes for patients. Herein, we design a novel phototheranostic agent with optical features in the biological window of the electromagnetic spectrum via encapsulating a newly synthesized phthalocyanine dye within biocompatible protein nanoparticles, allowing the targeted fluorescence imaging and synergistic dual therapy of ovarian cancer. The nanosized agent displays great biocompatibility and enhanced aqueous biostability and photothermal activity, as well as high reactive-oxygen-species generation efficiency. To achieve the active targeting of the desired malignant tissue and suppress the rapid clearance of the photosensitive agent from the peritoneal cavity, the nanoparticles are biofunctionalized with an anti-folate receptor antibody. A2780 ovarian cancer cells are employed to confirm the improved targeting capabilities and the in vitro cytotoxic efficiency of the theranostic nanoparticles after exposure to a 660 nm LED lamp; upon measurement via MTT and flow cytometry assays, a significant 95% decrease in the total number of viable cells is seen. Additionally, the therapeutic performance of our newly designed nanoparticles was evaluated in vivo, via real-time thermal monitoring and histopathological assays, upon the irradiation of tumour-bearing mice with a 660 nm LED lamp (0.05 W cm-2). Foremost, separately from steady-state fluorescence imaging, we found that, via utilizing FLIM investigations, the differences in fluorescence lifetimes of antibody biofunctionalized and non-functionalized nanoparticles can be correlated to different intracellular localization and internalization pathways of the fluorescent agent, which is relevant for the development of a cutting-edge method for the detection of cancer cells that overexpress folate receptors at their surfaces.

Photodynamic Therapy Using a New Folate Receptor-Targeted Photosensitizer on Peritoneal Ovarian Cancer Cells Induces the Release of Extracellular Vesicles with Immunoactivating Properties

Often discovered at an advanced stage, ovarian cancer progresses to peritoneal carcinoma, which corresponds to the invasion of the serosa by multiple tumor implants. The current treatment is based on the combination of chemotherapy and tumor cytoreduction surgery. Despite the progress and standardization of surgical techniques combined with effective chemotherapy, post-treatment recurrences affect more than 60% of women in remission. Photodynamic therapy (PDT) has been particularly indicated for the treatment of superficial lesions on large surfaces and appears to be a relevant candidate for the treatment of microscopic intraperitoneal lesions and non-visible lesions. However, the impact of this therapy on immune cells remains unclear. Hence, the objective of this study is to validate the efficacy of a new photosensitizer [pyropheophorbide a-polyethylene glycol-folic acid (PS)] on human ovarian cancer cells and to assess the impact of the secretome of PDT-treated cells on human peripheral blood mononuclear cells (PBMC). We show that PS, upon illumination, can induce cell death of different ovarian tumor cells. Furthermore, PDT using this new PS seems to favor activation of the immune response by inducing the secretion of effective cytokines and inhibiting the pro-inflammatory and immunosuppressive ones, as well as releasing extracellular vesicles (EVs) prone to activating immune cells. Finally, we show that PDT can activate CD4+ and CD8+ T cells, resulting in a potential immunostimulating process. The results of this pilot study therefore indicate that PS-PDT treatment may not only be effective in rapidly and directly destroying target tumor cells but also promote the activation of an effective immune response; notably, by EVs. These data thus open up good prospects for the treatment of micrometastases of intraperitoneal ovarian carcinosis which are currently inoperable.

[Microscopic peritoneal metastases of epithelial ovarian cancers. Clinical relevance, diagnostic and therapeutic tools]

Understanding the biology and progression mechanisms of peritoneal metastases in ovarian epithelial cancers (EOC) is important because peritoneal carcinomatosis is present or will occur during surveillance of a majority of patients. Despite the clinical remission achieved after complete macroscopic cytoreductive surgery and platinum-based chemotherapy, 60% of patients will develop peritoneal recurrence. This suggests that microscopic lesions, which are not eradicated by surgery may be present and may participate in the mechanisms leading to peritoneal recurrence. This paper discusses current available data on microscopic peritoneal metastases, their diagnosis and their treatment. We reviewed all publications dealing with microscopic peritoneal metastases of EOC between 1980 and 2017. The most recent and most relevant publications dealing with the treatment modalities of these metastases were selected. Peritoneal and epiploic microscopic localizations would occur in 1.2 to 15.1% of cases at early-stage and are not treated during conventional surgery. They could represent a potential therapeutic target. Local treatments (intraperitoneal chemotherapy, photodynamic therapy, fluorescence-guided surgery) seem to be necessary in addition to surgery and chemotherapy and may help reduce the risk of peritoneal recurrence. The place of these treatments in the management of EOC remains to be defined by subsequent researches.

[Intraperitoneal photodynamic therapy for peritoneal metastasis of epithelial ovarian cancer. Limits and future prospects]

High peritoneal recurrence rate in advanced epithelial ovarian cancer after complete macroscopic cytoreductive surgery and platinum-based chemotherapy, raises the issue of peritoneal microscopic disease management and requires the development of additional locoregional treatment strategies. Photodynamic therapy is an effective treatment already applied in other medical and surgical indications. After administration of a photosensitizer which accumulates in cancer cells, illumination with a light of adequate wavelength may induce photochemical reaction between photosensitizer and tissue oxygen which lead to reactive oxygen species production and cytotoxic phenomenon. Photodynamic therapy's ability to treat superficial lesions disseminated on large area makes it an excellent candidate to insure destruction of microscopic peritoneal metastases in addition to macroscopic cytoreductive surgery in order to decrease peritoneal recurrence rate. Development of intraperitoneal photodynamic therapy has been limited by its poor tolerance related to the lack of specificity of photosensitizers and the location of the metastases in proximity to adjacent intraperitoneal organs. Our aim is to review clinical data concerning intraperitoneal photodynamic therapy and epithelial ovarian cancer to identify the limits of this strategy and to provide solutions which may be applied to solve these barriers and enable safe and effective treatment. Targeted photosensitizers and innovative illumination solutions are mandatory to continue research in this field and to consider the feasibility of clinical trials.

[Specific folic-acid targeted photosensitizer. The first step toward intraperitoneal photodynamic therapy for epithelial ovarian cancer]

OBJECTIVE

Epithelial ovarian cancer (EOC) management remains association of debulking surgery in combination with platinum-based chemotherapy. Sixty percent of women with EOC considered in remission will develop recurrent disease. An option to improve the completion of cytoreductive surgery may be the use of photodynamic therapy to induce necrosis of peritoneal metastases. A limit of this technique was the toxicity induced by the lack of specificity of old-generation photosensitizer (PS) for tumor tissue if the light could not be specifically applied. To solve this problem, a solution is the design of selective PS. Folate receptor is a promising target for EOC targeted therapy. We present preclinical results concerning properties of a folic-acid targeted photosensitizer.

METHOD

Preclinical studies have been performed in vitro on murine and human cell lines of EOC and in vivo with a preclinical model of peritoneal carcinomatosis (Fisher F344 rat/NuTu-19 cell line). They aimed to precise the ability of PS to target specifically tumor tissue, to emit specific fluorescence, and to obtain cell death.

RESULTS

Tissue quantification of the PS showed specific incorporation of the folate-targeted PS within tumor tissue. Specificity for ovarian cancer metastases is better than previously reported with others photosensitizers (tumor-to-normal tissue ratio 9.6). We could detect specific fluorescence in vitro and in vivo on peritoneal metastases. Folic-acid targeted PDT allows to obtain human EOC cells death.

CONCLUSION

Specific PS may allow the development of efficient and safe intraperitoneal PDT procedure, which could play a role in the prevention of EOC peritoneal recurrences.

Dealing with microscopic peritoneal metastases of epithelial ovarian cancer. A surgical challenge

Understanding biology and progression mechanisms of peritoneal metastases of epithelial ovarian cancer (EOC) is a cornerstone in the knowledge and the comprehensive management of the disease. Despite clinical remission after the association of complete cytoreductive surgery and platinum-based chemotherapy, peritoneal recurrence still occurs in 60% of patients. Eligible studies, published from 1980 to June 2016, were retrieved through ClinicalTrials.gov, MEDLINE, Cochrane databases and bibliography searches. We reviewed all publications that deals with microscopic peritoneal metastases of EOC in French and English. To discuss expected benefits of intraperitoneal (IP) chemotherapy, fluorescence-guided surgery or IP photodynamic therapy, we reviewed most recent and relevant studies. The final reference list was generated on the basis of originality and relevance to the broad scope of this review. Published data concerning early-stage ovarian cancer suggest that occult peritoneal or epiploic metastases are present in 1.2%-15.1% of cases. In the frequent case of advanced-stage disease, residual microscopic lesions are ignored by conventional surgery. We are convinced that microscopic peritoneal metastases are a relevant surgical therapeutic target. This article discusses existing data on microscopic peritoneal metastases, the treatment indications, the diagnostic and therapeutic surgical approaches to be developed and their expected benefits. A local therapeutic strategy to target microscopic lesions is needed in addition to complete macroscopic cytoreductive surgery to decrease the rate of peritoneal recurrence. Intraperitoneal chemotherapy, and targeted photodynamic therapy could play a role in this new paradigm. The roles of these different options must be defined by future researches.

Assessment of the specificity of a new folate-targeted photosensitizer for peritoneal metastasis of epithelial ovarian cancer to enable intraperitoneal photodynamic therapy. A preclinical study

BACKGROUND

Ovarian cancer's prognosis remains dire after primary therapy. Recurrence rate is disappointingly high as 60% of women with epithelial ovarian cancer considered in remission will develop recurrent disease within 5 years. Special attention to undetected peritoneal metastasis during surgery is necessary as they are the main predictive factors of recurrences. Folate Receptor α (FRα) shows promising prospects in targeting ovarian cancerous cells and intraperitoneal photodynamic therapy (PDT) could be a solution in addition to macroscopic cytoreductive surgery to treat peritoneal micrometastasis. The aim of this preclinical study is to assess the specificity of a folate-targeted photosensitizer for ovarian peritoneal micrometastasis.

METHODS

We used the NuTu-19 epithelial ovarian cancer cell line to induce peritoneal carcinomatosis in female Fischer 344 rats. Three groups of 6 rats were studied (Control (no photosensitizer)/Non-conjugated photosensitizer (Porph)/Folate-conjugated photosensitizer (Porph-s-FA)). Four hours after the administration of the photosensitizer, animals were sacrificed and intraperitoneal organs tissues were sampled. FRα tissue expression was evaluated by immunohistochemistry. Tissue incorporation of photosensitizers was assessed by confocal microscopy and tissue quantification.

RESULTS

FRα is overexpressed in tumor, ovary, and liver whereas, peritoneum, colon, small intestine, and kidney do not express it. Cytoplasmic red endocytosis vesicles observed by confocal microscopy are well correlated to FRα tissue expression. Photosensitizer tissue quantification shows a mean tumor-to-normal tissue ratio of 9.6.

CONCLUSION

We demonstrated that this new generation folate-targeted photosensitizer is specific of epithelial ovarian peritoneal metastasis and may allow the development of efficient and safe intraperitoneal PDT procedure.