This PDF file contains the front matter associated with SPIE Proceedings Volume 11220, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

Photodynamic therapy (PDT) can elicit different cellular responses depending on sub-cellular sites of photodamage. Targeting lysosomes or mitochondria leadd to death by apoptosis, while ER photodamage can result in apoptosis and paraptosis. Autophagy is cytoprotective unless lysosomes are the primary target. We propose that the optimal targeting profile involves lysosomes, mitochondria and ER. Lysosomal phototoxicity is not limited by autophagy and can promote pro-apoptotic effects that magnify the lethality of mitochondrial photodamage. Targeting ER can be effective even in cells with an impaired apoptotic program since this will not affect paraptotic death.

Despite the concept of Photodynamic Therapy (PDT) being over a century old and regulatory approvals being worldwide for limited indications, PDT is not as broadly used for cancer treatment as promising pre-clinical observations might indicate. One of reasons maybe that it is primarily viewed as a local therapy, yet it is used in patients with advanced disease often in the palliative setting and with metastatic disease. The effect of PDT on metastatic disease has not been studied in any detail. We have reported both an increase and a decrease of metastatic burden. Increased survival in tumor bearing mice along with a decrease in metastatic burden has been demonstrated in both immune competent and immune deficient mice. While in immune competent mice this observation has been attributed to the activation of the mouse immune system, the explanation is less clear in immune suppressed mice (patients?).

In recent years much work has been done to show treatment efficacy using daylight as the activation mechanism of PpIX-based PDT for non-melanoma skin cancers and pre-cancerous actinic keratosis. Many previous studies assume sufficient fluence is delivered during a 2-3 hour period, but fail to consider shifts in the UV spectral composition throughout the day and transient weather conditions. Using a model-based approach we have developed a dose planning application to provide clinicians with information regarding minimum necessary treatment times. Clinical photobleaching data comparing indoor daylight and conventional red-light PDT have been collected to test the viability of this model.

Clinical use of photodynamic therapy (PDT) is widespread for treatment of actinic keratosis (AKs) based upon ALA induced Protoporphyrin IX (PpIX). Dosimetry of the PpIX levels at the point-of-care can help guide critical decisions in PDT, since studies have shown that initial PpIX accumulation and PDT-induced photobleaching serve as strong indicators for patient outcomes in treatment. Here, we present clinical results using a point-probe spectral dosimeter alongside a translational wide-field cellphone fluorescence system to study outcomes of indoor-daylight PDT for treatment of AKs. The outcomes of this study help advance adoption of point-of-care dosimetry for PDT guidance and helps establish threshold treatment parameters for indoor-daylight PDT.

Photodynamic diagnosis and therapy (PDD and PDT) involve the use of photochemical reactions induced by light irradiation with a photosensitizer for the detection and treatment of cancer cells and tissues. 5-Aminolevukinic acid (5-ALA) is a clinically used drug for PDT (5-ALA-PDT) in glioblastoma and bladder cancer. However, the conventional 5-ALA-PDT using visible light sours is not effective for the deep portion of organs and tissues. In this study, to overcome the limitation in penetration depth of 5-ALA-PDT, we developed two-photon excited 5-ALA-PDT system with NIR fiber laser for the effective treatment of peritoneal dissemination in gastric cancer.

Currently, photodynamic therapy (PDT) of primary tumors in peritoneal organs is limited by the lack of specificity of photosensitizers (PSs) and availability of appropriate laparoscopy for accurate and dexterous PDT optical fiber deployment. Invasive procedures are often required in the conventional approach, leads to significant side effects such as bleeding and extended recovery time. The purpose of this study is to design and evaluate a soft robot system for targeted and minimally invasive PDT of intraperitoneal tumors. Our soft robot system is fabricated with silicone materials to enable safe interaction with the abdominal organs. Compared to the conventional laparoscopic device, this soft robot system can be translated, bent, and rotated to reach the desired target by using three high-resolution DC motors. A miniature camera (ENA-10005-AS, Enable Inc.) is integrated with the soft robot to enable the intraoperative image guidance while reaching the target. A hollow channel was created within the soft robot so as to deploy the optical fiber towards the tumor. We conducted interstitial PDT using a peritoneal ovarian tumor mouse model and targeted near infrared photosensitizer. After the PS was injected, the optical fiber was inserted into the tumors through the soft robot. We found that PDT treatment greatly inhibited tumor growth. Our preliminary results suggest that our soft robot system may have great potential in the PDT treatment of intraperitoneal tumors.

Graphene quantum dots (GQD) are one of the most promising antimicrobial agents since they possess high germicidal activity against a broad range of microbes. In our project, we aim to investigate GQD with methylene blue (MB) as an effective, inexpensive and available compound which will hold even higher antimicrobial activity and lower toxicity toward human blood. GQDs were grown by focusing nanosecond laser pulses into benzene and were later combined with MB. The Gram-negative bacteria, Escherichia coli, and Gram-positive bacteria, Micrococcus luteus, were deactivated by GQD/MB. Detailed characterization was performed with transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), UV-Visible (UV-Vis), and photoluminescence (PL) spectra. Furthermore, MBGQD singlet oxygen generation was investigated by measuring the rate of photobleaching. Combining MB with GQDs caused enhanced singlet oxygen generation. Our results show that the MB-GQD combination is more effective than QGD and MB alone in destroying bacteria. MTT assay was used to determine if GQDs in dark conditions caused human cellular side-effects and affected cancer and non-cancer cellular viability. We found that even high concentrations of GQDs do not alter viability under dark conditions. These results suggest that the MB-GQD combination is a promising form of photodynamic therapy. Further, the cytotoxicity of GQDs, MB and MB-GQD mixture toward MCF-7 breast cancer cells were evaluated.

This study investigated the use of clinoptilolite zeolites (CZs) as the drug adsorbent and their ability to release 5- Aminolevulinic acid (5-ALA) and porphyrin (Zn-TBut3 PyP) in the presence of biomolecules, by absorption and fluorescence spectrometry and multiphoton spectroscopy. About one-third of the porphyrin adsorbed on to CZs was released in the presence of biomolecule such as insulin. In-vitro measurements show that the skin absorbed the dye more than 1.5 times for ALA-CZ and porphyrin-CZ complex compared to non-CZ form. The measurements on chicken skin were also performed using multiphoton microscopy which compared the penetration of the dye into the skin in the presence and absence of CZ. These results demonstrate the potential of CZ in the efficient adsorption and biomolecule favoured release of 5-ALA and porphyrin in biological systems.

We have initiated a clinical trial to test the hypothesis that we hypothesize that PDT with the photosensitizing pro-drug ALA and vitamin D3 can be applied to treat anal (pre)malignancy with acceptable toxicity and light dose delivery (NCT02698293) . Here, we report on the design of the trial, a custom apparatus to deliver light while measuring PpIX fluorescence and tissue optical properties, validation of apparatus and initial toxicity in the first treated patients.

Aminolevulinate-based photodynamic therapy (ALA-PDT) is an effective treatment for cutaneous pre-cancers (Actinic Keratoses; AK) and Basal Cell Carcinoma (BCC), the most common skin malignancies. When administered in a conventional regimen with 1-4 h of ALA preincubation prior to light exposure, ALA-PDT elicits stinging pain during illumination that patients find objectionable. To avoid this pain, we have described a new regimen called metronomic PDT (mPDT) which is similar to daylight PDT but uses blue light (Kaw et al, J Am Acad Dermatol 2019). Metronomic PDT is not only painless but also nearly as effective as conventional PDT for AK lesion clearance. In this investigation, murine models of AK induced by repeated UVB exposure were treated with mPDT, followed by time-course analyses of immune responses in the lesions harvested. Our preliminary data showed that relative to conventional PDT, cell death (apoptosis) and generation of Reactive Oxygen Species (ROS) were compromised in mPDT samples. However, relative to untreated controls, enhanced recruitment/infiltration of immune cells that mediate innate immunity [neutrophils (Ly6G+) and macrophages (F4/80+)] was observed at early times after mPDT. Just as importantly, enhanced presence of cells regulating adaptive immune responses [T cells (CD3+, CD8+ and Foxp3+)] was observed at later times post mPDT. Activation of calreticulin and HMGB1 (markers of Damage Associated Molecular Patterns, DAMPs) were also observed in mPDT treated lesions. Our results suggest that mPDT can be just as effective as conventional PDT for treatment of skin cancer and pre-cancer, and that the therapeutic mechanisms may involve immune cell responses triggered by metronomic PDT.

Basal cell carcinoma (BCC) is a common skin cancer caused by chronic UV exposure. Photodynamic therapy (PDT), a non-surgical, non-scarring modality, can clear superficial BCC lesions but thick (nodular) lesions are more refractory. To improve overall PDT efficacy for BCC, we are conducting a clinical trial to ascertain whether neoadjuvant treatment with Vitamin D prior to ALA-PDT (5-aminolevulinic acid and blue light) can improve the rate of tumor clearance. Study patients undergo three PDT treatments, with sessions spaced two months apart. Prior to each PDT session, patients take a Vitamin D pill or a placebo pill for up to 14 days, in a randomized double-blind fashion. To quantify tumor shrinkage after each PDT treatment, we are employing high-precision 3D photography using a LifeViz Micro camera (Quantificare, Inc). With this approach, individual tumors are rendered in 3D coordinate space and important parameters such as tumor height and volume, which could not otherwise be obtained using standard photography, are measured. Amongst 45 BCC lesions evaluated, 17 (37.8%) disappeared after the first PDT treatment, 12 (26.7%) after the second, and 7 (15.6%) after the third, for a final clinical clearance rate of 80%. For treatment-responsive lesions, decreases in absolute volume after the first, second, and third treatment were 81.4%, 66.2%, and 80.9%, respectively. Corresponding decreases in lesion surface area were 78.8%, 70.2%, and 77.6%. The similar incremental changes in lesion size after each treatment reassures us that this technique can be used to successfully determine BCC clearance rates ± Vitamin D.

Photodynamic diagnosis (PDD) of gastric cancer with protoporphyrin IX (PpIX) induced by 5-aminolevulinic acid (ALA) will lead to a method to estimate the invasive depth. The excitation light for ALA-based PDD is attenuated by absorption and scattering of the mucosal tissue according to its wavelength and the difference contains the fluorophore depth information. To realize the method to estimate the invasive depth for the intramucosal cancer, this study investigated the differences of the attenuation rate between two excitation wavelengths. Considering the optical properties of mucosa and PpIX, relationships between the invasive depths of cancer containing PpIX and the fluorescence intensity ratios detected from the mucosa were estimated using a numerical model. An experiment was also performed using a pellet made of epoxy resin containing PpIX. The excitation lights with wavelengths of 405 and 505 nm having the same power density were each used to irradiate the pellet placed at the fluorophore depth of 0 mm, 1.0 mm, and 1.7 mm from the mucosal surface to obtain fluorescence images, and the average fluorescence intensities of the images were evaluated. The numerical and experimental results suggested the possibility to estimate the fluorophore depth of the PpIX fluorescence source by comparing the fluorescence images with excitation lights at wavelengths of 405 and 505 nm.

Reactive oxygen species explicit dosimetry (ROSED) has been recently developed and demonstrated to be able to better correlate with treatment outcome in both preclinical type I and type II PDT. ROSED involves direct measurements of in-vivo light fluence (rate), in-vivo photosensitizer concentration and tissue oxygenation to calculate for reacted ROS concentration ([ROS]_rx) generated by PDT processes. In this study, we demonstrated ROSED in ALA-mediated PDT for mice bearing radiation-induced fibrosacorma (RIF) tumor. PDT treatments were performed using single or fractionated illumination to a same total fluence of 140Jcm^-2. The effects of light fractionation on the total reacted [ROS]_rx and treatment outcomes were evaluated.

Determination of in-vivo tissue optical properties for anal photodynamic therapy (PDT) is challenging due to the light integrating-sphere effect in an enclosed cylindrical cavity. We developed a model for optical properties determination for anal PDT from measurements of light fluence rate inside a cylindrical cavity submerged in tissue-mimicking liquid phantoms. Measurements are performed in a set of phantoms with known optical properties (μ_a = 0.1-0.9 cm^-1) and (μ_s’ = 6.65-19.95 cm^-1) and the primary and scatter light fluence rates are determined. We developed an analytical expression to relate scatter light fluence rate measured in an enclosed cylindrical geometry to the surrounding tissue optical properties in tissue-simulating liquid phantoms. In addition, the accuracy of determining tissue optical properties using the model was evaluated by comparing the recovered optical properties to the known optical properties of a series of independent test phantoms.

A novel approach to monitor photosensitizer accumulation and photobleaching in the course of photodynamic therapy (PDT) with the use of nanoconstructs based on the simultaneous fluorescence (FL) and optoacoustic (OA) imaging is implemented. A liposome nanoconstructs employed in this studies contain benzoporphyrin derivatives (BPD) which serve as a photosensitizer and secondly, as a fluorophore, and the fluorescent IRDye800 dye acting as an additional contrasting agent due to its high quantum yield. FL provides visualization of BPD and IRDye800 distribution, while OA principle allows for BPD-absorption based imaging of tumor and its vascular environment. We demonstrate the results of a preliminary in vivo study with combined FL and OA custom-made setups on a NUDE mouse with human glioblastoma U- 87. The results of this studies show a hemorrhage in the tumor area on the OA images obtained @532 nm after PDT that is not visually detected, but confirmed with the following histological verification. Fast nanoconstructs accumulation (< 10 min) was observed using FL imaging with the concentration in tumor only 10% higher than in surrounding tissues. We believe that the ratio of nanoconstructs accumulation in tumor can be significantly increased using target approach.