Advanced-stage ovarian cancer becomes extremely challenging to treat effectively using current surgical and chemotherapy methods due to factors such as peritoneal metastasis, incomplete resection, and drug resistance. While photoimmunotherapy is emerging as a promising option for unresectable metastases, its full potential often goes unrealized due to varying treatment outcomes. This research effort aims to enhance the reliability, safety, and effectiveness of photoimmunotherapy for peritoneal metastases by combining targeted nanotechnology, fluorescence-guided intervention, and a state-of-the-art medical laser system.
Peritoneal metastasis, incomplete resection, and drug resistance render advanced-stage ovarian cancer virtually incurable with current surgical and chemotherapy approaches. Photoimmunotherapy is increasingly used to treat unresectable metastases, but many innovations are lost in translation due to heterogeneous treatment effects. This study integrates targeted nanotechnology, fluorescence-guided intervention, and a medical laser system to improve the safety, efficacy, and consistency of photoimmunotherapy for peritoneal metastases.
Hepatocellular carcinoma (HCC) is the second most common cause of cancer deaths worldwide, with 800,000 deaths per year. Since surgical options for HCC patients are limited, minimally invasive ablative therapies are critical to treat early-stage HCC; however, their cost and need for specialized equipment and expertise prevent widespread use in underprivileged populations. Here, we propose a lower-cost Light-Activatable, Sustained-exposure Ethanol Injection Technology (LASEIT) to augment current options for underprivileged patients.
This conference presentation was prepared for the Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXXI conference at SPIE BiOS, SPIE Photonics West 2023.
This conference presentation was prepared for the Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXXI conference at SPIE BiOS, SPIE Photonics West 2023.
Contrast-enhanced fluorescent imaging has the potential to improve patient outcomes. A critical challenge that has not been rigorously evaluated is the potential photocytoxicity of the fluorophores used for imaging procedures. In this study, we have used a modified 3T3 Neutral Red Uptake assessment strategy to evaluate 4 imaging dyes and 2 known photosensitizers generating reactive molecular species. Results shed light on the relative photocytotoxicity of tested agents and provide strong evidence on the effectiveness of the method. These methods will provide a foundation for standardizing photo-safety testing of clinical fluorescence imaging products.
Photoimmunotherapy employs antibody-photosensitizer constructs (photoimmunoconjugates) for targeted cancer ablation through the generation of reactive oxygen species. While this approach enhances cancer cell specificity, it sacrifices cellular uptake. This study addresses this limitation through two strategies with an emphasis on anti-cancer immunogenicity: 1) utilizing fluid shear stress to mediate delivery, and 2) leveraging nanoengineering approaches to maximize photoimmunoconjugate payload. Results reveal that fluid shear stress promotes photosensitizer delivery and anti-tumor immune response while modulating subcellular localization. By shedding light on improved delivery strategies and formulations, this study generates important implications for the clinical implementation of photoimmunotherapy.
Liposomes have revolutionized the field of photomedicine. Photodynamic therapy (PDT) using Visudyne®, a liposomal photosensitizer formulation, has helped many patients globally. Since the FDA approved Visudyne® in 2002, countless studies have examined strategies to further improve the therapeutic index of lipid-based photosensitizing nanoconstructs. While liposomes can improve the pharmacokinetics of hydrophobic photosensitizers, they could also modulate cellular uptake and singlet oxygen production. Furthermore, it is evident that there are other immunological and toxicological considerations for the design of liposomal drugs. Accordingly, there is now an emerging trend to engineer carrier-free nanodrugs. Here, we developed a pure-drug nanoparticle using the clinically used verteporfin photosensitizer (termed nanoVP) for photodynamic applications. We validated the effects of nanoVP in three contexts: 1) cytotoxic PDT, 2) subtherapeutic PDT, and 3) dark toxicity. Using a brain cancer murine model, we showed that light activation of nanoVP reduced tumor volume by up to 54% compared to liposomal VP. Fluorescence imaging revealed that nanoVP had a superior tumor-to-liver tissue ratio (~0.92) compared to liposomal VP (~0.4). We further studied nanoVP-mediated PDT at subtherapeutic doses to achieve photodynamic priming (PDP). PDP has been shown to enhance drug delivery, activate antitumor immunity, and sensitize tumors to chemotherapy. This approach is particularly relevant in the brain, where high doses of PDT can result in edema, neurotoxicity, and even animal death. Using a rat model, we demonstrated that nanoVP-assisted PDP improved blood-brain barrier permeability and accumulation of a model drug (Evans Blue dye) in rat brains by >5 fold. Minimal to no brain damage was observed. Lastly, under dark conditions, we validated that nanoVP significantly reduced viability while liposomal VP stimulated cancer cell growth. Results from this work demonstrate the utility of nanoVP for cancer treatment. The development of pure-drug photosensitizing nanoparticles for photodynamic applications could further revolutionize the field of photomedicine.
Combination treatments are most effective when targeting different cancer survival and growth pathways. Nanotechnology combined with photochemistry provides a unique opportunity to simultaneously deliver and activate multiple drugs that target all major regions of a cancer cell—plasma membrane, cytoplasm, and nucleus. In this study, we developed a light-activatable nanocomplex that selectively and simultaneously deliver three clinically relevant therapeutic agents at a synergistic drug ratio to destroy ovarian cancer cells, while sparing normal tissues.
Rationally designed bioconjugates of photosensitizers have been shown to enhance the photochemical effect of photodynamic therapy (PDT) via altering the sub-cellular localization of the photosensitizers or modulating the function of ATP-binding cassette (ABC) transporters. P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) are the two key members that contribute to chemoresistance and PDT resistance in cancer. Here, we introduce a porphyrin-based phospholipid conjugation strategy to circumvent and inhibit the efflux function of ABC drug transporters. Our results show the porphyrin-phospholipid conjugate enhances the photosensitizer accumulation and modulates the enzymatic activity and protein integrity of ABCB1 and ABCG2.
Ovarian cancer typically spreads throughout the peritoneal cavity, and despite standard of care treatments (surgical debulking and chemotherapy), the five-year relative survival rate remains below 50%. The use of antibody-photosensitizer conjugates (photoimmunotherapy) has emerged as a promising modality to achieve targeted photosensitizer delivery to ovarian cancer cells. In this study, we investigate epithelial growth factor (EGFR)-targeted PIT coupled with inhibition of prostaglandin E2 receptor 4 (EP4), a G-coupled-receptor that contributes to cancer progression and intracellularly transactivates EGFR. This potent triple combination significantly attenuates the metastatic behavior of ovarian cancer cells through simultaneously inducing photochemical damage and modulating protein expression.
Recent advances in optical imaging have the potential to significantly improve patient outcomes. Among the most promising approaches under development is contrast-enhanced fluorescence imaging, which can be performed with molecular targeting to enhance tumor visualization. One key issue that has not been rigorously addressed is the potential phototoxicity of these fluorophores. In this study, we have used a commercial cell-free assay to qualify the singlet oxygen production rate in approved (ICG, Methylene Blue) and unapproved (IRDye700, IRDye800) fluorophores. Results shed light on the relative phototoxicity of each agent and will help to establish standardized methods for photochemical safety testing.
Significance: Previous studies have been performed to image photosensitizers in certain organs and tumors using fluorescence laminar optical tomography. Currently, no work has yet been published to quantitatively compare the signal compensation of fluorescence laminar optical tomography with two-dimensional (2-D) imaging in tissues.
Aim: The purpose of this study is to quantify the benefit that fluorescence laminar optical tomography holds over 2-D imaging. We compared fluorescence laminar optical tomography with maximum intensity projection imaging to simulate 2-D imaging, as this would be the most similar and stringent comparison.
Approach: A capillary filled with a photosensitizer was placed in a phantom and ex vivo rodent brains, with fluorescence laminar optical tomography and maximum intensity projection images obtained. The signal loss in the Z direction was quantified and compared to see which methodology could compensate better for signal loss caused by tissue attenuation.
Results: The results demonstrated that we can reconstruct a capillary filled with benzoporphyrin derivative photosensitizers faithfully in phantoms and in ex vivo rodent brain tissues using fluorescence laminar optical tomography. We further demonstrated that we can better compensate for signal loss when compared with maximum intensity projection imaging.
Conclusions: Using fluorescence laminar optical tomography (FLOT), one can compensate for signal loss in deeper parts of tissue when imaging in ex vivo rodent brain tissue compared with maximum intensity projection imaging.
Glioblastoma has a high rate of recurrence due to treatment methods often failing to penetrate the blood brain barrier. To overcome this limitation, photodynamic priming (PDP) can be used to increase tissue permeability. In this study we investigate the feasibility of using fluorescence laminar optical tomography (FLOT) to provide quantitative distribution information on photodynamic drug in the brain to optimize the timing of PDP. The project will result in a non-invasive way to quantify the concentration of photodynamic drug in the brain. This would allow for optimized treatment times, leading to improved patient outcomes.
Over the past few decades, considerable attention has been given to improving the photoactivity and biocompatibility of hydrophobic photosensitizing drugs for light-activatable biomedical applications. It is increasingly clear that photosensitizing biomolecules, based on chemical conjugation or association of photosensitizers with biomolecules (e.g., lipids, polymers, antibodies, and Pluronic), strongly influence the performance of a given photosensitizer in biological environments. However, the numerous studies that have revealed PSBMs are not readily comparable as they cover a wide range of macromolecules, evaluated across a range of experimental conditions. Here, we prepared and characterized a series of well-defined PSBMs and pure drug crystal based on a clinically used photosensitizer—benzoporphyrin derivative (BPD). Our results illuminate the variable trafficking and end effects of clinically relevant PSBMs and BPD nanocrystals, providing valuable insights into methods of PSMB evaluation as well as strategies to select PSMBs based on subcellular targets and cytotoxic mechanisms. More importantly, these results demonstrate that biologically-informed combinations of PSBMs and carrier-free photosensitizers to target multiple subcellular organelles may lead to enhanced therapeutic effects in gliomas.
Cancer patients often must confront the decision of whether to continue high dose chemotherapy at the expense of cumulative toxicities and high cost. Strategies to reduce the toxicity of these high dose regimens, while also retaining efficacy, have not been prioritized yet are sorely needed to preserve the performance status of these vulnerable patients. Here, we introduce a dual pronged approach to modulate the microenvironment of desmoplastic pancreatic tumors and enable significant dose de-escalation of the FDA approved frontline chemotherapeutic nanoliposomal irinotecan (nal-IRI) without compromising long-term tumor control. We demonstrate that light-based photodynamic priming (PDP) coupled with vitamin D receptor (VDR) activation targets cancer-associated microvasculature and fibroblasts to increase intratumoral nal-IRI and suppress pro-tumorigenic CXCL12/CXCR7 crosstalk. Combined optical and biochemical alteration of the tumor microenvironment enhances the efficacy of nal-IRI to enable a 75% dose de-escalation, resulting in improved tolerability with retained efficacy. Strategies aimed at modifying the tumor landscape to increase susceptibility represents a promising and relatively underexplored approach to enable dose de-escalation of toxic chemotherapeutics, and may simultaneously improve patient outcomes and quality-of-life.
A range of cellular, architectural, and physical cues in the tumor microenvironment influence the intrinsic and acquired resistance mechanisms that lead to treatment failure. Strategies that leverage photodynamic therapy (PDT), a photochemistry-based biophysical treatment modality, to regionally target and prime stubborn tumor populations may be essential to realizing durable improvements in cancer management while minimizing toxicity from traditional agents. Capturing these attributes in rationally-designed combinations has shown promise by synergistically reducing tumor area in 3D models, and durably controlling tumor burden in vivo. Among the areas that remain understudied is the influence of mechanical forces, such as hydrodynamic shear stress, on resistance, and the development of 3D tumor models and in vivo models that account for physical stress. To evaluate and optimize PDT regimens, and PDT-based combinations, designed to overcome resistance to conventional therapies due to physical stress, a multi-faceted approach is needed. Here the impact of hydrodynamic stress is evaluated in bioengineered 3D tumor models in the context of ovarian cancer. The potential value of using biologically inspired in vitro models to guide customized, rationally-designed PDT-based combination regimens will be presented.
Drug resistance to conventional therapies remains a major cause of treatment failure, tumor recurrence and dismal survival rates for patients with advanced stage cancers. Photodynamic therapy (PDT) provides an opportunity to exploit photochemically-triggered death mechanisms via targeting of sub-cellular, cellular and stromal compartments to overcome treatment resistance in unresponsive populations of stubborn disease. The informed design of mechanism-based combinations is emerging as increasingly important to targeting resistance and improving the efficacy of conventional treatments, while minimizing toxicity. PDT has been shown to synergize with conventional agents and to overcome the evasion pathways that cause resistance. Increasing evidence shows that PDT-based combinations cooperate mechanistically with, and improve the therapeutic index of, traditional chemotherapies. These and other findings emphasize the importance of including PDT as part of comprehensive treatment plans for cancer, particularly in complex disease sites. Identifying effective combinations requires a multi-faceted approach that includes the development of bioengineered cancer models and corresponding image analysis tools. The presentation will focus on the molecular and phenotypic basis of verteporfin PDT-based enhancement of chemotherapeutic efficacy and predictability in complex 3D models and in vivo models, with a particular emphasis on ovarian and pancreatic cancer.
Given the consistently poor prognoses for some of the most difficult-to-treat cancers, rapidly translatable treatment regimens that offer improvements in outcomes are much needed. The repurposing of FDA approved non-cancer drugs presents an opportunity to design clinically feasible, novel combinations of therapies with a mechanistic rationale, to overcome resistance and survival pathways that render many current treatments ineffective. Tetracyclines are a class of antibiotics that demonstrate potential for such repurposing, as they have also been shown by others to affect a wide range of targets in cancer. Notably, the unique structure of tetracyclines allows them to act through both light activated and non-light mediated mechanisms. While light activation of tetracyclines can result in singlet oxygen production, their non-light mediated targets include inhibition of DNA repair enzymes and modulation of hypoxia-inducible markers, among others. With these mechanisms in mind, we seek to elucidate the benefit of including tetracyclines as part of an already promising, mechanistically cooperative photochemotherapy combination for ovarian cancer. In ovarian cancer, the dismal rates of recurrence and survival associated with the aggressive disease further emphasize the need to mechanistically reinforce treatments regimens. Thus, the results will highlight insights into the cooperative effect of repurposed tetracyclines on treatment response and molecular markers, both in vitro and in a challenging mouse model of disseminated ovarian cancer.
It is increasingly evident that the most effective cancer treatments will involve interactive regimens that target multiple non-overlapping pathways, preferably such that each component enhances the others to improve outcomes while minimizing systemic toxicities. Toward this goal, we developed a combination of photodynamic therapy and irinotecan, which mechanistically cooperate with each other, beyond their individual tumor destruction pathways, to cause synergistic reduction in orthotopic pancreatic tumor burden. A three-way mechanistic basis of the observed the synergism will be discussed: (i) PDT downregulates drug efflux transporters to increase intracellular irinotecan levels. (ii) Irinotecan reduces the expression of hypoxia-induced marker, which is upregulated by PDT. (iii) PDT downregulates irinotecan-induced survivin expression to amplify the apoptotic and anti-proliferative effects. The clinical translation potential of the combination will also be highlighted.
Glioblastoma (GBM) is an aggressive cancer with dismal survival rates and few new treatment options. Fluorescence
guided resection of GBM followed by photodynamic therapy (PDT) has shown promise in several chemo- or
radiotherapy non-responsive GBM treatments clinically. PDT is an emerging light and photosensitizer (PS) mediated
cytotoxic method. However, as with other therapeutic modalities, the outcomes are variable largely due to the nonpersonalization
of dose parameters. The variability can be attributed to the differences in heterogeneous photosensitizer
accumulation in tumors. Building upon our previous findings on utilizing PS fluorescence for designing tumor-specific
PDT dose, we explore the use of photoacoustic imaging, a technique that provides contrast based on the tissue optical
absorption properties, to obtain 3D information on the tumoral photosensitizer accumulation. The findings of this study
will form the basis for customized photodynamic therapy for glioblastoma and have the potential to serve as a platform
for treatment of other cancers.
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