In vivo fluorescence detection of ovarian cancer in the NuTu-19 epithelial ovarian cancer animal model using 5-aminolevulinic acid (ALA)

Photodynamic Diagnosis and Therapy for Peritoneal Carcinomatosis from Gastrointestinal Cancers: Status, Opportunities, and Challenges

Selective accumulation of a photosensitizer and the subsequent response in only the light-irradiated target are advantages of photodynamic diagnosis and therapy. The limited depth of the therapeutic effect is a positive characteristic when treating surface malignancies, such as peritoneal carcinomatosis. For photodynamic diagnosis (PDD), adjunctive use of aminolevulinic acid- protoporphyrin IX-guided fluorescence imaging detects cancer nodules, which would have been missed during assessment using white light visualization only. Furthermore, since few side effects have been reported, this has the potential to become a vital component of diagnostic laparoscopy. A variety of photosensitizers have been examined for photodynamic therapy (PDT), and treatment protocols are heterogeneous in terms of photosensitizer type and dose, photosensitizer-light time interval, and light source wavelength, dose, and dose rate. Although several studies have suggested that PDT has favorable effects in peritoneal carcinomatosis, clinical trials in more homogenous patient groups are required to identify the true benefits. In addition, major complications, such as bowel perforation and capillary leak syndrome, need to be reduced. In the long term, PDD and PDT are likely to be successful therapeutic options for patients with peritoneal carcinomatosis, with several options to optimize the photosensitizer and light delivery parameters to improve safety and efficacy.

[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.

A dual-channel endoscope for quantitative imaging, monitoring, and triggering of doxorubicin release from liposomes in living mice

Doxorubicin (Dox) is approved for use in liposomal form for the treatment of ovarian cancer. We previously developed a long-circulating Dox formulation in liposomes containing small amounts of porphyrin-phospholipid, which enables on-demand drug release with near-infrared irradiation. In this study, we present and evaluate a dual-modal, dual-channel light endoscope that allows quantitative reflectance and fluorescence imaging for monitoring of local Dox concentrations in target areas. The endoscope consists of two flexible imaging fibers; one to transmit diagnostic and therapeutic light to the target, and the other to detect fluorescent and reflected light. Thus, the endoscope serves for imaging, for light delivery to trigger drug release, and for monitoring drug concentration kinetics during drug release. We characterized the performance of this endoscope in tissue phantoms and in an in vivo model of ovarian cancer. This study demonstrates the feasibility of non-invasive, quantitative mapping of Dox distribution in vivo via endoscopic imaging.

Image-guided surgery in gynecologic oncology

Image-guided surgery is a relevant way to reduce surgical morbidity and maximize cytoreductive surgery approach especially in ovarian cancer. Sentinel lymph node detection is a promising approach to avoid radical lymph node dissection and is slightly becoming standard in daily practice in endometrial and cervical cancer surgery even if it needs to be evaluated more precisely. Regarding carcinomatosis of ovarian origin, detection and treatment of microscopic disease could be appropriate to avoid local recurrences. Photodiagnosis and photodynamic therapy are innovative techniques that allow to precise limits of excision (fluorescence-guided surgery) and to treat microscopic disease. Further developments of those strategies are necessary to become standard diagnosis tools and treatment options.

[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.

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.

Photodynamic diagnosis with 5-aminolevulinic acid for intraoperative detection of peritoneal metastases of ovarian cancer: A feasibility and dose finding study

OBJECTIVE

With a prospective feasibility study, we aimed to analyse the effect of different time points for application and dosage of preoperative oral 5-aminolevulinic acid administration for photodynamic diagnosis of peritoneal metastases in ovarian cancer patients.

MATERIALS AND METHODS

In this prospective cohort study patients were randomly divided into three different groups. 5-Aminolevulinic acid was orally administered 3-14 hours before surgery using a dosage of 1 mg/kg, 4-9 hours using 10 mg/kg, and 9-16 hours using 10 mg/kg, respectively. Fluorescence was recorded intraoperatively using endoscopic equipment. The number and localization, of fluorescing nodules were documented. To analyze sensitivity and specificity samples from fluorescent and non-fluorescent tissues were evaluated histologically. Plasma protoporphyrin concentrations as well as any adverse events were assessed perioperatively.

RESULTS

In total, 26 patients suspected for ovarian cancer underwent intraoperative photodynamic diagnosis with 5-aminolevulinic acid. Most of them suffered from advanced cancer, 72% from FIGO-Stage IIIc. No severe adverse events were observed. Orally applied 5-aminolevulinic acid with a dosage of 1 mg/kg revealed no detectable fluorescence. However, at a dosage of 10 mg/kg fluorescence of metastatic tissue was significantly stronger than of non-affected tissue. If administered 4-9 hours preoperatively best detection rates for peritoneal metastases were obtained resulting in a sensitivity of 75% and a specificity of 100%.

CONCLUSIONS

Photodynamic diagnosis with 5-aminolevulinic acid leads to safe and specific fluorescence detection of peritoneal metastases. 5-Aminolevulinic acid should be used at a dosage of at least 10 mg/kg 4-9 hours preoperatively. Further phase I-II studies are recommended. Lasers Surg. Med. 49:169-176, 2017. © 2016 Wiley Periodicals, Inc.

Photochemical activation of MH3-B1/rGel: a HER2-targeted treatment approach for ovarian cancer

HER2-targeted therapy has been shown to have limited efficacy in ovarian cancer despite frequent overexpression of this receptor. Photochemical internalization (PCI) is a modality for cytosolic drug delivery, currently undergoing clinical evaluation. In the present project we studied the application of PCI in combination with the HER2-targeted recombinant fusion toxin, MH3-B1/rGel, for the treatment of ovarian cancer. The SKOV-3 cell line, resistant to trastuzumab- and MH3-B1/rGel- monotherapy, was shown to respond strongly to PCI of MH3-B1/rGel to a similar extent as observed for the treatment-sensitive SK-BR-3 breast cancer cells. Extensive hydrolytic degradation of MH3-B1/rGel in acidic endocytic vesicles was indicated as the mechanism of MH3-B1/rGel resistance in SKOV-3 cells. This was shown by the positive Pearson's correlation coefficient between Alexa488-labeled MH3-B1/rGel and Lysotracker in SKOV-3 cells in contrast to the negative Pearson's correlation coefficient in SK-BR-3 cells. The application of PCI to induce the release of MH3-B1/rGel was also demonstrated to be effective on SKOV-3 xenografts. Application of PCI with MH3-B1/rGel was further found highly effective in the HER2 expressing HOC-7 and NuTu-19 ovarian cancer cell lines. The presented results warrant future development of PCI in combination with MH3-B1/rGel as a novel therapeutic approach in preclinical models of ovarian cancer.

Photodynamic diagnosis for detection of peritoneal carcinomatosis

BACKGROUND

Peritoneal carcinomatosis is the dissemination of cancer in the peritoneal cavity secondary to abdominal or extra-abdominal malignancies. Accurate assessment of the disease's burden is a challenge because of the complexity of the peritoneal cavity and the small size of the metastatic nodules. Photodynamic diagnosis (PDD) is an emerging technology in tumor diagnosis. A photosensitizer is administered, which is preferentially taken up by cancer cells. The photosensitizer emits fluorescence when exposed to a light of a specific wavelength. This helps distinguish cancer from normal tissues.

METHODS

We systematically reviewed the evidence for using PDD in detecting peritoneal carcinomatosis in both animal and human literature. Both Medline and EMBASE databases were searched (November 2014). The titles and the abstracts of all retrieved citations were inspected, and the full articles of the relevant articles were obtained.

RESULTS

A total of 12 human and 18 animal studies were included. Clinical studies have shown PDD to be a safe modality with no significant adverse effects. It increases the detection of malignant peritoneal nodules by 21%-34% in comparison with white light alone. The sensitivity and specificity of PDD were reported at 83%-100% and 95%-100%, respectively. These findings were supported by multiple animal studies, which have shown an increase in the sensitivity of tumor detection when using PDD (72%-91%) in comparison with white light alone (39%).

CONCLUSIONS

PDD is a promising modality, which improves the detection of peritoneal carcinomatosis lesions. Further research, however, should investigate the impact of PDD on the patients' therapeutic management and final outcomes.

Establishment of Fischer 344 rat model of ovarian cancer with lymphatic metastasis

PURPOSE

To establish a model of ovarian cancer with highly lymphatic metastasis in immunocompetent rats.

METHODS

Thirty-two female Fischer 344 rats were divided randomly and equally into two groups: footpad group and intraperitoneal (i.p.) group. At 8 weeks after injection with NuTu-19 ovarian cancer cells, lymphatic metastasis were analyzed by pathohistology; body weight was monitored per week, Survival curves were determined by Kaplan-Meier analysis.

RESULTS

Footpad injection could efficiently generate the lymphatic metastasis; specifically, the incidences of metastasis in the ipsilateral popliteal, inguinal and para-iliac lymph nodes were 100% (8/8), 75% (6/8), and 37.5% (3/8), respectively. The mean volume and weight of the ipsilateral popliteal lymph nodes were 0.405 ± 0.096 cm(3) and 0.418 ± 0.118 g in footpad group. However, no lymphatic metastasis lesions were found in i.p. group. Moreover, Kaplan-Meier analysis showed that the average survival time of the footpad group was significantly longer than that of the i.p. group (18.429 ± 1.112 vs. 10.286 ± 0.505 weeks).

CONCLUSIONS

Our experiments suggest that footpad injection is a very efficient method to generate ovarian cancer with lymphatic metastasis in an immune-competent animal, and we believe that this model will be very helpful for shedding light on the mechanism of lymphogenous metastasis and developing novel therapeutic targets for ovarian cancer patients.

Formulation of bioadhesive hexylaminolevulinate pellets intended for photodynamic therapy in the treatment of cervical cancer

Photodynamic therapy has a great potential in the treatment of cervical cancer. The aim of this study was to develop bioadhesive pellets containing hexylaminolevulinate (HAL), a precursor of the photoactive substance PpIX, with a fast release for vaginal drug delivery. Pellets were produced by extrusion/spheronization, and Carbopol(®) 934 was used to obtain bioadhesive properties. A 2(2)-factorial design with center point investigating the HAL content (1 and 10%, w/w) and Carbopol(®) 934 content (1 and 8%, w/w) was set up. The most suitable formulations were mechanically stable and showed bioadhesive properties toward vaginal tissue. The drug load was released within 20 min in phosphate buffer pH 4 and 6.8 in the in vitro dissolution test. The stability of HAL in the pellet formulations varied, but the most stable formulation showed 96-97% HAL remaining in the formulation after 6-7 weeks of storage at accelerated temperature conditions (40 °C). The investigated formulations seem promising for vaginal delivery of HAL.

In vitro optimization of EtNBS-PDT against hypoxic tumor environments with a tiered, high-content, 3D model optical screening platform

Hypoxia and acidosis are widely recognized as major contributors to the development of treatment resistant cancer. For patients with disseminated metastatic lesions, such as most women with ovarian cancer (OvCa), the progression to treatment resistant disease is almost always fatal. Numerous therapeutic approaches have been developed to eliminate treatment resistant carcinoma, including novel biologic, chemo, radiation, and photodynamic therapy (PDT) regimens. Recently, PDT using the cationic photosensitizer EtNBS was found to be highly effective against therapeutically unresponsive hypoxic and acidic OvCa cellular populations in vitro. To optimize this treatment regimen, we developed a tiered, high-content, image-based screening approach utilizing a biologically relevant OvCa 3D culture model to investigate a small library of side-chain modified EtNBS derivatives. The uptake, localization, and photocytotoxicity of these compounds on both the cellular and nodular levels were observed to be largely mediated by their respective ethyl side chain chemical alterations. In particular, EtNBS and its hydroxyl-terminated derivative (EtNBS-OH) were found to have similar pharmacological parameters, such as their nodular localization patterns and uptake kinetics. Interestingly, these two molecules were found to induce dramatically different therapeutic outcomes: EtNBS was found to be more effective in killing the hypoxic, nodule core cells with superior selectivity, while EtNBS-OH was observed to trigger widespread structural degradation of nodules. This breakdown of the tumor architecture can improve the therapeutic outcome and is known to synergistically enhance the antitumor effects of front-line chemotherapeutic regimens. These results, which would not have been predicted or observed using traditional monolayer or in vivo animal screening techniques, demonstrate the powerful capabilities of 3D in vitro screening approaches for the selection and optimization of therapeutic agents for the targeted destruction of specific cellular subpopulations.

Shining new light on 3D cell motility and the metastatic process

Understanding tissue architecture and physical and chemical reciprocity between cells and their microenvironment provides vital insights into key events in cancer metastasis, such as cell migration through three-dimensional (3D) extracellular matrices. Yet, many mechanistic details associated with metastasis remain elusive due to the difficulty of studying cancer cells in relevant 3D microenvironments. Recently, optical imaging has facilitated the direct observation of single cells as they undertake fundamental steps in the metastatic processes. Optical imaging is also providing novel 'optical biomarkers' with diagnostic potential that are linked to cell-motility pathways associated with metastasis, and these can to help guide new approaches to cancer diagnosis and therapy. Here we present recent advances in one subclass of optical imaging of particular promise for cellular imaging - multiphoton microscopy - that can be used to improve the detection of malignant cells as well as advance our understanding of the cell biology of cancer metastasis.

Benefits of nanoencapsulation for the hypercin-mediated photodetection of ovarian micrometastases

The high recurrence and lethality of ovarian cancer at advanced stages is problematic, especially due to the development of numerous micrometastases scattered throughout the abdominal cavity. Fluorescence photodetection (PD) used in combination with surgical resection of malignant tissues has been suggested to improve recovery. Based on promising in vivo results for the detection of bladder cancer, hypericin (Hy), a natural photosensitizer (PS), stands as a good candidate for the photodetection of ovarian cancer. However, due to its hydrophobicity, systemic administration of Hy is problematic. Polymeric nanoparticles (NPs) help to overcome these delivery and stability problems and enable intravenous administration of Hy. In this study, Hy-loaded NPs of polylactic acid were produced with the following properties: (i) mean size of 268 nm, (ii) negative zeta potential, (iii) low residual surfactant and (iv) drug loading of 3.7 % (w/w). The potential of hypericin-loaded nanoparticles for the fluorescence photodetection of ovarian metastases in Fischer 344 rats bearing ovarian tumours was compared to free drug. The selectivity of Hy administered with both formulations was assessed first by fluorescence endoscopy, and then quantified after tissue extraction. The results showed an improved selective accumulation of Hy in ovarian micrometastases when NPs were used.

Comparison of Aminolevulinic Acid– and Hexylester Aminolevulinate–Induced Protoporphyrin IX Fluorescence for the Detection of Ovarian Cancer in a Rat Model

OBJECTIVES

This study set out to compare the photodetection of peritoneal micrometastases in an ovarian cancer model following administration of two precursors of protoporphyrin IX (PpIX): 5-aminolevulinic acid (ALA) and hexylester aminolevulinate (He-ALA).

METHODS

ALA or He-ALA (100 mg/kg) was injected into the peritoneal cavity of 16 rats with induced peritoneal metastases of ovarian cancer. Two hours later, the tumors were visualized laparoscopically using both white light for standard exploration and blue light for fluorescence. Peritoneal micrometastases were counted. Fluorescence intensities of tumoral and normal surrounding tissues were compared. The distribution of PpIX throughout the peritoneum was studied on frozen biopsies using fluorescence microscopy and correlated with pathological findings.

RESULTS

The number of micrometastases detected by the fluorescence blue mode was significantly higher (p < 0.05) than with standard white light for both ALA (235 versus 198) and He-ALA application (248 versus 199). The mean fluorescence intensity ratio between tumor and normal surrounding tissue was significantly (p < 0.05) higher for He-ALA (1.55 +/- 0.1) compared to ALA (1.45 +/- 0.1). Fluorescence microscopy confirmed that the PpIX fluorescence remained limited to cancer cells. Macroscopically fluorescing nodules were histopathologically confirmed as malignant.

CONCLUSION

He-ALA is an excellent precursor for PpIX synthesis, giving the highest PpIX fluorescence contrast between normal and tumoral peritoneal tissues. Imaging with He-ALA improves the detection of peritoneal metastases compared to ALA.

Hypericin-loaded nanoparticles for the photodynamic treatment of ovarian cancer

A photodynamic approach has been suggested to improve diagnosis and therapy of ovarian cancer. As Hypericin (Hy), a natural photosensitizer (PS) extracted from Hypericum perforatum, has been shown to be efficient in vitro and in vivo for the detection or treatment of other cancers, Hy could also be a potent tool for the treatment and detection of ovarian cancer. Due to its hydrophobicity, systemic administration of Hy is problematic. Thus, polymeric nanoparticles (NPs) of polylactic acid (PLA) or polylactic-co-glycolic acid (PLGA) were used as a drug delivery system. Hy-loaded NPs were produced with the following characteristics: (i) size in the 200-300 nm range, (ii) negative zeta potential, (iii) low residual PVAL and (iv) drug loading from 0.03 to 0.15% (w/w). Their in vitro photoactivity was investigated on the NuTu-19 ovarian cancer cell model derived from Fischer 344 rats and compared to free drug. Hy-loaded PLA NPs exhibited a higher photoactivity than free drug. Increasing light dose or incubation time with cells induced an enhanced activity of Hy-loaded PLA NPs. Increased NP drug loading had a negative effect on their photoactivity on NuTu-19 cells: at the same Hy concentration, the higher was the drug loading, the lower was the phototoxic effect. The influence of NP drug loading on the Hy release from NPs was also investigated.

Photochemically stimulated drug delivery increases the cytotoxicity and specificity of EGF-saporin

Epidermal growth factor receptor (EGFR) targeting has become a major field in both cancer research and therapy. In the present study an EGF-saporin affinity toxin has been established and evaluated in two EGFR overexpressing cancer cell lines. The binding of saporin to EGF did not influence the ribosome-inactivating activity of saporin as measured by a luminescence based reticulocyte lysate assay. Control experiments, using untargeted saporin, EGFR-negative cell lines and competition with EGF and anti-EGFR antibody were used to document selective uptake of the affinity toxin. One limitation in administration of macromolecular-drugs is lysosomal degradation. Photochemical internalization (PCI) is a modality for cytosolic release of macromolecules based on photochemical rupture of endocytic membranes and subsequent drug release. It was shown that PCI increases the toxicity of EGF-saporin significantly in EGFR-positive cells. EGF binding to saporin enhanced the PCI-induced cytotoxicity in NuTu-19 cells about 1000-fold when the photochemical treatment alone killed 50% of the cells. In conclusion, PCI of EGF-saporin is a promising method for increasing the efficiency of protein toxin-based cancer therapies. PCI of targeting toxins also exert a triple tumour-selectivity; utilization of an affinity toxin, preferential accumulation of the photosensitizer in neoplastic lesions, and site-directed light activation.

Time-dependent hexaminolaevulinate induced protoporphyrin IX distribution after topical application in patients with cervical intraepithelial neoplasia: A fluorescence microscopy study

BACKGROUND AND OBJECTIVES

Compared to the conventional management of cervical intraepithelial neoplasia (CIN) the potential advantage of photodynamic therapy (PDT) for the treatment of cervical human papilloma virus (HPV)-related disease encompasses a minimal invasive procedure with reduced risk of profuse bleeding as a consequence of conization, and possibly more favorable long-term results avoiding cervical stenosis. At present little is known about the precise time-dependent distribution and histological localization of hexaminolaevulinate (HAL) induced protoporphyrin IX (PPIX) fluorescence in healthy tissue and in CIN. The aim of this study was to use ex vivo fluorescence microscopy to determine whether PPIX is selectively induced by neoplastic cells of the cervical epithelium at various times after topical application.

STUDY DESIGN/MATERIALS AND METHODS

Cold cream containing 0.5% HAL was applied by means of cervical cap over various periods of time. We analyzed 52 healthy cervical mucosa and 84 CINs.

RESULTS

At time delay 100 (+/-10) minutes, high epithelial fluorescence and a significant selectivity between epithelium and underlying lamina propria was found. By contrast, no significant difference between healthy and neoplastic tissues, or between low and high-grade epithelial dysplasia (P > or = 0.05), was observed at any time point.

CONCLUSIONS

Application of HAL 0.5% cream to the cervix induced selective fluorescence in epithelial cells. The optimal ratio with a homogeneous PPIX distribution was obtained after 100 ( +/- 10) minutes cream application, which should be evaluated further for PDT.

Laparoscopic fluorescence detection of ovarian carcinoma metastases using 5-aminolevulinic acid-induced protoporphyrin IX

BACKGROUND

The aim of the current clinical study was to evaluate the in vivo fluorescence detection of ovarian carcinoma metastases in a second-look laparoscopic procedure after intraperitoneally applied 5-aminolevulinic acid (ALA).

METHODS

Five hours before laparoscopic surgery, ALA was applied intraperitoneally via short infusion in a concentration of 30 mg/kg bodyweight in a sterile, 1% solution. Application of ALA resulted in the endogenous production of the fluorescent photosensitizer, protoporphyrin IX (PP IX). The Combilight PDD 5133 system served as a light source, permitting the switch from white light mode to blue light mode to excite the PP IX accumulated in the ovarian tissue specimens. By means of blue light illumination, intraperitoneally located red fluorescent lesions, which were suspected to be metastases, underwent a biopsy. In addition, several biopsy specimens were taken from nonfluorescent areas of the peritoneal cavity.

RESULTS

In 13 of 29 patients, ovarian carcinoma was confirmed histologically or cytologically. In 12 of these patients, metastases were visible by red fluorescence. In total, 123 biopsies were performed. Comparison of histologic assessment of the biopsy specimens with the fluorescence detection showed that strong red fluorescence had a sensitivity of 92% for detecting tumor tissue on specimens. In only 2% of all biopsy specimens was endometriosis observed in benign tissue specimens using fluorescence. In four of 13 patients with ovarian carcinoma, lesions were detected under fluorescence, which were not observed under white light illumination.

CONCLUSIONS

Laparoscopic fluorescence detection of endogenous PP IX after intraperitoneal application of ALA may provide a higher sensitivity of finding peritoneal metastases of epithelian ovarian carcinoma compared with conventional laparoscopy. Direct visualization of in vivo fluorescence after ALA application may improve the early detection of intraperitoneal ovarian carcinoma micrometastases. The high tissue selectivity of PP IX accumulation in tumor tissue specimens also offers the opportunity for therapeutic approaches using photodynamic therapy in the future.

Photodynamic diagnosis of ovarian cancer using hexaminolaevulinate: a preclinical study

The unfailing detection of micrometastases during surgery of patients suffering from ovarian cancer is mandatory for the optimal management of this disease. Thus, the present study aimed at determining the feasibility of detecting micrometastases in an ovarian cancer model using the intraperitoneal administration of the photosensitiser precursor hexaminolaevulinate (HAL). For this purpose, HAL was applied intraperitoneally at different concentrations (4-12 mM) to immunocompetent Fischer 344 rats bearing a syngeneic epithelial ovarian carcinoma. The tumours were visualised laparoscopically using both white and blue light (D-light, Karl Storz, Tuttlingen, Germany), and the number of peritoneal micrometastases detected through HAL-induced photodiagnosis (PD) was compared to standard white light visualisation. Fluorescence spectra were recorded with an optical fibre-based spectrofluorometer and the fluorescence intensities were compared to the protoporphyrin IX (PpIX) fluorescence induced by 5-aminolevulinic acid under similar conditions. The number of metastases detected by the PD blue light mode was higher than when using standard white light abdominal inspection for all applied concentrations. Twice as many cancer lesions were detected by fluorescence than by white light inspection. The hexyl-ester derivative produced higher PpIX fluorescence than its parent substance aminolevulinic acid at the same concentration and application time. Fluorescence contrast between healthy and cancerous tissue was excellent for both compounds. To overcome poor diagnostic efficiency and to detect peritoneal ovarian carcinoma foci in the large surface area of the human peritoneal cavity, HAL fluorescence-based visualisation techniques may acquire importance in future and lead to a more correct staging of early ovarian cancer.

Laparoscopic photodynamic diagnosis of ovarian cancer using 5-aminolevulinic acid in a rat model

OBJECTIVE

The objective of this study was to determine the efficacy and sensitivity of laparoscopic photodynamic diagnosis to detect 5-aminolevulinic acid (ALA)-induced fluorescent tumors in an animal model.

METHODS

Cancer cells were injected into the peritoneum of rats to induce peritoneal carcinomatosis. After 3-4 weeks, ALA was administered to establish fluorescence in tumor nodules. All intraperitoneal surfaces were inspected using fluorescence and white light laparoscopy. Suspicious lesions were then biopsied in vivo under either fluorescence or white light laparoscopic guidance. Fluorescence intensities of the cancerous lesions compared to normal tissues were determined. A pathologist blinded to our clinical impression analyzed all biopsied specimens. We compared the sensitivity of fluorescence and white light laparoscopic-guided detection of cancerous lesions and determined the clinical utility of fluorescent photodynamic diagnosis in detecting metastatic ovarian cancer.

RESULTS

Forty-three biopsies were performed in vivo under laparoscopic fluorescent guidance and 42 biopsies were taken using white light in various regions of the peritoneal surface from nine rats. Ten biopsies were also removed from nonfluorescent regions as nontumor controls. Cancerous lesions showed significantly higher fluorescent intensity compared to noncancerous lesions. Cancerous lesions that were difficult to differentiate from normal surrounding tissue under white light conditions were clearly detected by ALA-induced fluorescence. The average size of these metastatic lesions biopsied under fluorescent light was 1.0 mm (range: 0.3-2.5) compared to 1.5 mm (range: 0.5-2.9) with white light illumination (P < 0.05).

CONCLUSIONS

Fluorescent laparoscopic detection of micrometastatic ovarian cancer using ALA is significantly more sensitive than white-light laparoscopy in detecting smaller cancerous lesions in an ovarian cancer rat model. Human trials are indicated.

Localization and staging of cervical intraepithelial neoplasia using double ratio fluorescence imaging

A phase zero evaluation of a new fluorescence imaging technique for diagnosing cervical intraepithelial neoplasia (CIN) was performed. The fluorescence imaging prototype performed quantitative imaging of Protoporphyrin induced by a topically applied aminolevulinic acid using double ratio (DR) fluorescence imaging technique developed by our group. A total of 38 patients were in the protocol, with 16 colposcopically selected for biopsy. Fluorescence images of these 16 patients were taken, 19 sites were biopsied, and the disease was staged histopathologically. DR fluorescence imaging of the cervix using our general purpose prototype appeared to be cumbersome but feasible. In four cases strongly localized fluorescent hotspots were observed at the location where the disease was colposcopically visible. In the other cases the fluorescence showed a more diffuse multifocal image. The value of the DR determined at the site of biopsy correlated in a statistically significant way with the histopathologically determined stage of the disease [Spearman rank correlation, r=0.881, p<0.001 (confidence interval 0.7044-0.9552)]. This suggests that noninvasive staging of CIN using this technique is feasible. We believe that the results of this study justify the development of a dedicated device that combines regular white light colposcopy with DR fluorescence imaging.

Intraperitoneal photodynamic therapy in the Fischer 344 rat using 5-aminolevulinic acid and violet laser light: a toxicity study

OBJECTIVE

Our study was designed to investigate 5-aminolevulinic acid (ALA) as a candidate for intraperitoneal photodynamic therapy (IP-PDT). The toxicity of IP-PDT and the effects of IP-PDT on abdominal and pelvic organs, particularly the small intestine, were investigated after ALA administration and illumination with violet laser light.

STUDY DESIGN AND RESULTS

The toxicity of IP-PDT was evaluated in Fischer 344 rats in two ways. In the first part of the study local PDT effects on the intestine were analyzed histologically. Violet laser light (lambda: 406-415 nm) was applied as a 2 cm diameter spot on the intestine 3 h after intraperitoneal (i.p.) administration of 50 mg/kg ALA. (A) Histological tissue samples were taken 0 min, 6 h and 1, 2 and 3 days after treatment (optical dose 3.2 J/cm(2)). Immediately after local PDT (3.2 J/cm(2), 50 mg/kg ALA) showed no effect on the intestine. However, 6 h post PDT there was complete destruction of the mesothelial lining and the outer (longitudinal) smooth muscle. Ganglion cells of the myenteric (Auerbach) plexus were also destroyed. The inner circular smooth muscle, the muscularis mucosa and the lamina propria were unharmed. Marked lymphectasia was present at this time. (B) To determine the threshold light dose of tissue destruction caused by PDT, different optical doses (1.6, 3.2, 6.4 J/cm(2)) were administered and histologic analysis of tissue samples were obtained 1 day post treatment. Destruction of the entire external musculature, submucosal structures and muscularis mucosa of the intestine at the illumination site could be observed above 1.6 J/cm(2) (50 mg/kg ALA). In the second part of the study whole peritoneal cavity PDT (WPC-PDT) was performed by illumination of the whole peritoneal cavity with 1.6 J/cm(2) violet light 3 h after ALA administration using different drug doses (200, 100 and 50 mg/kg). WPC-PDT showed lethal toxicity with a drug dose above 50 mg/kg ALA at 1.6 J/cm(2). The probable cause of death in the first 3 days after IP-PDT was rhabdomyolysis, whereas when death occurred at longer time intervals, megaintestine associated with significant damage could be observed; however, without perforation of the intestinal wall.

CONCLUSION

In rats WPC-PDT with 50 mg/kg ALA, 1.6 J/cm2 at lambda=415 nm was the maximum tolerable light dose. This dose is likely to be above the threshold of destruction of ovarian cancer micrometastasis.

Routine experimental system for defining conditions used in photodynamic therapy and fluorescence photodetection of (non-) neoplastic epithelia

A common method to induce enhanced short-term endogenous porphyrin synthesis and accumulation in cell is the topical, systemic application of 5-aminolevulinic acid or one of its derivatives. This circumvents the intravenous administration of photosensitizers normally used for photodynamic therapy (PDT) of fluorescence photodetection. However, in the majority of potential medical indications, optimal conditions with respect to the porphyrin precursor or its pharmaceutical formulation have not yet been found. Due to ethical restrictions and animal right directives, the number of available test objects is limited. Hence, definition and use of nonanimal test methods are needed. Tissue and organ cultures are a promising approach in replacing cost intensive animal models in early stages of drug development. In this paper, we present a tissue culture, which can among others be used routinely to answer specific questions emerging in the field of photodynamic therapy and fluorescence photodetection. This technique uses mucosae excised from sheep paranasal sinuses or pig bladder, which is cultured under controlled conditions. It allows quasiquantitative testing of different protoporphyrin IX precursors with respect to dose-response curves and pharmacokinetics, as well as the evaluation of different incubation conditions and/or different drug formulations. Furthermore, this approach, when combined with the use of electron microscopy and fluorescence-based methods, can be used to quantitatively determine the therapeutic outcome following protoporphyrin IX-mediated PDT.

Photodetection of cervical intraepithelial neoplasia using 5-aminolevulinic acid-induced porphyrin fluorescence

BACKGROUND

Screening for cervical carcinoma and its precursors is based on cervical cytology and diagnostic colposcopy. Despite the decrease in the incidence of cervical carcinoma in countries with a good screening program, this rate of decline is leveling off. Known problems are false-negative rates of cytology and low specificity of colposcopy. This clinical study examined the diagnostic potential of porphyrin fluorescence in patients with cervical intraepithelial neoplasia Grade 1-3 (CIN 1-3).

METHODS

Sixty-eight women attending our colposcopy clinic underwent a gynecologic examination, including cytology, human papillomavirus (HPV) testing, and colposcopy. They received 10 mL 0.5% or 1.0% 5-aminolevulinic acid (5-ALA) topically. After 30-360 minutes, real-time image analysis was performed, and spectra were obtained from 685 sites.

RESULTS

Due to rapid photobleaching, 0.5% 5-ALA proved ineffective for fluorescence assessment. Using 1% 5-ALA, the authors found that fluorescence intensities correlated with incubation time; however, fluorescence contrast showed a maximum at 60-90 minutes (ratio 11:1). HPV DNA positive lesions showed significantly higher fluorescence. Fluorescence imaging after 60-90 minutes achieved similar sensitivity and specificity compared with colposcopy in detecting CIN with 94% and 51% versus 95% and 50%, respectively. However, the specificity was markedly improved by fluorescence spectroscopy, achieving 75%. The evaluation of spectral measurements revealed significantly higher values for CIN compared with normal tissue and for CIN 2/3 compared with CIN 1 (P < 0.001).

CONCLUSIONS

Using a time interval of 60-90 minutes after topical application of 1% 5-ALA, the authors observed specific porphyrin fluorescence of CIN. Fluorescence spectroscopy promises to become a valuable tool for the diagnosis of CIN.

In vivo detection of metastatic ovarian cancer by means of 5-aminolevulinic acid-induced fluorescence in a rat model

STUDY OBJECTIVES

To determine the feasibility of macroscopic visualization of small ovarian cancer metastases in vivo by fluorescence after intravenous administration of 5-aminolevulinic acid (ALA); to assess the time after drug injection when fluorescence of small metastases is maximum; and to correlate macroscopic in vivo fluorescence with both microscopic ex vivo fluorescence and histologic findings.

DESIGN

Controlled animal study (Canadian Task Force classification I).

SETTING

University-based facility.

SUBJECTS

Twenty-four healthy, female Fischer rats.

INTERVENTION

Diffuse peritoneal metastatic cancer was induced in Fischer 344 rats by intraperitoneal injection of 1 million syngeneic ovarian cancer cells (NuTu-19). Four weeks after induction ALA100 mg/kg was injected intravenously, and diagnostic laparotomy was performed 1, 3, 6, or 9 hours thereafter.

MEASUREMENTS AND MAIN RESULTS

The peritoneal cavity was illuminated with the Wood's lamp (ultraviolet light). Fluorescence was determined by direct visualization and compared with a calibrated fluorescent disk. Tissues were collected, sectioned, and examined by fluorescence and conventional light microscopy. Within 1 to 3 hours after intravenous injection of ALA, in vivo fluorescence of tumor nodules (diameter 0.4-5.0 mm) was macroscopically visible. Tumor-free peritoneum did not show fluorescence and was significantly distinguishable from cancer nodules. Fluorescence from intestinal tissues was comparable with tumor nodules. Microscopic fluorescence analysis showed similar values for tumor nodules and peritoneum. Stained histologic specimens of peritoneal surface revealed a superficial layer of cancer cells responsible for fluorescence. The time course of the fluorescence curve in the intestine peaked twice, at 1 and 6 hours after ALA injection. Macroscopically fluorescing nodules were histology confirmed as malignant.

CONCLUSIONS

Fluorescence detection of small cancer nodules after intravenous injection of ALA is feasible for nodules smaller than 0.5 mm on the peritoneum. One to 3 hours after drug injection is optimal for diagnosis of metastases.