Near infrared photoimmunotherapy in the treatment of pleural disseminated NSCLC: preclinical experience

Transformative effects of fluorescence imaging technologies on current vascular surgical practices: An updated review

Fluorescence imaging technologies have revolutionized vascular surgery by enabling real-time visualization of vascular anatomy, blood circulation, and tissue perfusion, thus improving intraoperative decision-making. This review provides a comprehensive analysis of key fluorescence modalities, including Fluorescence-Guided Surgery (FGS), Near-Infrared (NIR) fluorescence imaging, and Indocyanine Green (ICG) angiography, highlighting their roles in optimizing tissue perfusion assessment, vessel patency evaluation, and identifying anatomical variations. Unlike existing literature, this review addresses critical gaps in current practices by comparing these technologies and exploring their applications across a range of vascular procedures such as peripheral vascular surgery, coronary artery bypass grafting, and oncological operations. The review further delves into the potential future directions for fluorescence imaging in vascular surgery, emphasizing emerging technologies, challenges in clinical implementation, and how these advancements can enhance surgical precision, patient outcomes, and intraoperative guidance. By synthesizing the latest developments, this review offers valuable insights into the evolving role of fluorescence imaging in vascular surgery and its potential to transform surgical practices.

Photoinduced Actin Aggregation Involves Cell Death: A Mechanism of Cancer Cell Cytotoxicity after Near-Infrared Photoimmunotherapy

Near-infrared photoimmunotherapy (NIR-PIT) is a cancer treatment modality that uses antibody-photoabsorber (IR700) conjugates to destroy specific cells. The reaction between the antibody and photoabsorber is triggered by NIR-light, and this alters the shape and hydrophilicity of the conjugate. This photochemical reaction is responsible for NIR-PIT-induced cell death; however, the detailed mechanism underlying this effect remains unknown. In this study, we demonstrated that actin filaments underneath the cell membrane play an important role in NIR-PIT-induced cell death and that IR700 mediates the photochemical reaction of the conjugates, leading to actin filament aggregation upon NIR-light irradiation. The destruction of cortical actin beneath the cell plasma membrane allows water to flow into the cell based on osmotic conditions, resulting in cell rupture. This sequence of events may constitute the mechanism of NIR-PIT-induced cell death, making NIR-PIT a promising cancer treatment modality.

Targeted Elimination of Influenza Virus and Infected Cells with Near-Infrared Antiviral Photoimmunotherapy (NIR-AVPIT)

Background: Seasonal influenza causes significant morbidity and mortality each year. Since viruses can easily acquire drug-resistant mutations, it is necessary to develop new antiviral strategies with different targets. Near-infrared photoimmunotherapy (NIR-PIT) is a type of anti-cancer therapy that has recently attracted considerable attention, with favorable outcomes reported for several cancers. In this study, we investigated whether this approach could be used as a novel anti-influenza therapy to destroy influenza virus and infected cells. Methods: To evaluate the efficacy of near-infrared antiviral photoimmunotherapy (NIR-AVPIT), we prepared an anti-hemagglutinin (HA) monoclonal antibody without neutralizing activity against influenza A virus (FluV) labeled with IR-700 and reacted it with FluV and infected cells, as well as HA-expressing HEK293 cells. Results: NIR-AVPIT strongly inactivated FluV virions, suppressed cytopathic effects, and achieved more than a 4-log reduction in viral RNA amplification. Treatment of FluV-infected cells with the antibody-IR700 complex and NIR in the early stages of infection significantly inhibited viral propagation, and double treatment with time apart exerted a greater inhibitory effect. NIR-AVPIT rapidly induced morphological changes in HA-expressing HEK293 cells and inhibited the proliferation of these cells. Conclusions: These results suggest that NIR-AVPIT targeting HA antigens could inactivate FluV and eliminate infected cells in vitro. This strategy is a promising approach to treat various viral infections, including influenza.

Targeting endothelial permeability in the EPR effect

The characteristics of the primary tumor blood vessels and the tumor microenvironment drive the enhanced permeability and retention (EPR) effect, which confers an advantage towards enhanced delivery of anti-cancer nanomedicine and has shown beneficial effects in preclinical models. Increased vascular permeability is a landmark feature of the tumor vessels and an important driver of the EPR. The main focus of this review is the endothelial regulation of vascular permeability. We discuss current challenges of targeting vascular permeability towards clinical translation and summarize the structural components and mechanisms of endothelial permeability, the principal mediators and signaling players, the targeted approaches that have been used and their outcomes to date. We also critically discuss the effects of the tumor-infiltrating immune cells, their interplay with the tumor vessels and the impact of immune responses on nanomedicine delivery, the impact of anti-angiogenic and tumor-stroma targeting approaches, and desirable nanoparticle design approaches for greater translational benefit.

Contrast-enhanced ultrasound imaging for monitoring the efficacy of near-infrared photoimmunotherapy

BACKGROUND

Near-infrared photoimmunotherapy (NIR-PIT) is a promising cancer therapy combining NIR-light irradiation with an antibody and IR700DX, a light-sensitive substance, to destroy tumours. However, homogeneous irradiation is difficult because the light varies depending on the distance and tissue environment. Therefore, markers that indicate sufficient irradiation are necessary. Nanoparticles sized 10∼200 nm show enhanced permeation and retention within tumours, which is further enhanced via NIR-PIT (super enhanced permeability and retention, SUPR). We aimed to monitor the effectiveness of NIR-PIT by measuring SUPR.

METHODS

A xenograft mouse tumour model was established by inoculating human cancer cells in both buttocks of Balb/C-nu/nu mice, and NIR-PIT was performed on only one side. To evaluate SUPR, fluorescent signal examination was performed using QD800-fluorescent nanoparticles and NIR-fluorescent poly (d,l-lactide-co-glycolic acid) (NIR-PLGA) microparticles. Harmonic signals were evaluated using micro-bubbles of the contrast agent Sonazoid and contrast-enhanced ultrasound (CEUS) imaging. The correlation between SUPR immediately after treatment and NIR-PIT effectiveness on the day after treatment was evaluated.

FINDINGS

QD800 fluorescent signals persisted only in the treated tumours, and the intensity of remaining signals showed high positive correlation with the therapeutic effect. NIR-PLGA fluorescent signals and Sonazoid-derived harmonic signals remained for a longer time in the treated tumours than in the controls, and the kE value of the two-compartment model correlated with NIR-PIT effectiveness.

INTERPRETATION

SUPR measurement using Sonazoid and CEUS imaging could be easily adapted for clinical use as a therapeutic image-based biomarker for monitoring and confirming of NIR-PIT efficacy.

FUNDING

This research was supported by ARIM JAPAN of MEXT, the Program for Developing Next-generation Researchers (Japan Science and Technology Agency), KAKEN (18K15923, 21K07217) (JSPS), CREST (JPMJCR19H2, JST), and FOREST-Souhatsu (JST). Mochida Memorial Foundation for Medical and Pharmaceutical Research; Takeda Science Foundation; The Japan Health Foundation; and Princess Takamatsu Cancer Research Fund. Funders only provided financial support and had no role in the study design, data collection, data analysis, interpretation, and writing of the report.

In Vitro Comparative Study of Near-Infrared Photoimmunotherapy and Photodynamic Therapy

Near-infrared photoimmunotherapy (NIR-PIT) is a new phototherapy that utilizes a monoclonal antibody (mAb) against cancer antigens and a phthalocyanine dye, IRDye700DX (IR700) conjugate (mAb-IR700). Photodynamic therapy (PDT) is a combination therapy that utilizes photoreactive agents and light irradiation as well as NIR-PIT. In the present study, we compared these therapies in vitro. The characterization of cellular binding/uptake specificity and cytotoxicity were examined using two mAb-IR700 forms and a conventional PDT agent, talaporfin sodium, in three cell lines. As designed, mAb-IR700 had high molecular selectivity and visualized target molecule-positive cells at the lowest concentration examined. NIR-PIT induced necrosis and damage-associated molecular patterns (DAMPs), a surrogate maker of immunogenic cell death. In contrast, talaporfin sodium was taken up by cells regardless of cell type, and its uptake was enhanced in a concentration-dependent manner. PDT induced cell death, with the pattern of cell death shifting from apoptosis to necrosis depending on the concentration of the photosensitizer. Induction of DAMPs was observed at the highest concentration, but their sensitivity differed among cell lines. Overall, our data suggest that molecule-specific NIR-PIT may have potential advantages compared with PDT in terms of the efficiency of tumor visualization and induction of DAMPs.

Recent Advances in Localized Immunomodulation Technology: Application of NIR-PIT toward Clinical Control of the Local Immune System

Current immunotherapies aim to modulate the balance among different immune cell populations, thereby controlling immune reactions. However, they often cause immune overactivation or over-suppression, which makes them difficult to control. Thus, it would be ideal to manipulate immune cells at a local site without disturbing homeostasis elsewhere in the body. Recent technological developments have enabled the selective targeting of cells and tissues in the body. Photo-targeted specific cell therapy has recently emerged among these. Near-infrared photoimmunotherapy (NIR-PIT) has surfaced as a new modality for cancer treatment, which combines antibodies and a photoabsorber, IR700DX. NIR-PIT is in testing as an international phase III clinical trial for locoregional recurrent head and neck squamous cell carcinoma (HNSCC) patients (LUZERA-301, NCT03769506), with a fast-track designation by the United States Food and Drug Administration (US-FDA). In Japan, NIR-PIT for patients with recurrent head and neck cancer was conditionally approved in 2020. Although NIR-PIT is commonly used for cancer therapy, it could also be exploited to locally eliminate certain immune cells with antibodies for a specific immune cell marker. This strategy can be utilized for anti-allergic therapy. Herein, we discuss the recent technological advances in local immunomodulation technology. We introduce immunomodulation technology with NIR-PIT and demonstrate an example of the knockdown of regulatory T cells (Tregs) to enhance local anti-tumor immune reactions.

Trastuzumab-based near-infrared photoimmunotherapy in xenograft mouse of breast cancer

Near-infrared photoimmunotherapy (NIR-PIT) is a novel form of cancer treatment using conjugates of antibody against overexpressed antigens in cancers and photoabsorber IRDye700DX. HER2 is overexpressed in various cancers, for which molecular targeted therapy such as trastuzumab has been developed. The present study investigated the efficacy potential of HER2-targeted NIR-PIT using trastuzumab-IRDye700DX conjugate (Tra-IR700) in HER2-positive breast cancer. We first examined the reactivity of Tra-IR700 and the cytotoxicity of NIR-PIT in vitro. HER2-positive BT-474 and SK-BR-3 cells and HER2-negative BT-20 cells were used. Tra-IR700 fluorescence was only observed in HER2-positive breast cancer cell lines, and the fluorescence was localized to the cell surface. Furthermore, HER2-positive breast cancer cell lines treated with NIR-PIT showed swelling and blebbing shortly after irradiation, and eventually increased PI-positive dead cells. Next, tumor accumulation of Tra-IR700 and tumor damage by NIR-PIT were examined in vivo. Tra-IR700 was administered intravenously to a xenograft model in which BT-474 cells were implanted subcutaneously in BALB/c nude mice. Tra-IR700 fluorescence was the highest in tumor tissue 1 day after administration, and the fluorescence was localized to the cell membrane of tumor cells. At this time point, NIR-PIT resulted in diffuse necrosis of tumor tissues 1 day after irradiation. These results suggest that NIR-PIT with Tra-IR700 induces a highly selective therapeutic effect in a HER2-positive breast cancer model. NIR-PIT using Tra-IR700 is expected to be a novel treatment for HER2-positive cancers, including breast cancer.

Near Infrared Photoimmunotherapy: A Review of Recent Progress and Their Target Molecules for Cancer Therapy

Near infrared photoimmunotherapy (NIR-PIT) is a newly developed molecular targeted cancer treatment, which selectively kills cancer cells or immune-regulatory cells and induces therapeutic host immune responses by administrating a cancer targeting moiety conjugated with IRdye700. The local exposure to near-infrared (NIR) light causes a photo-induced ligand release reaction, which causes damage to the target cell, resulting in immunogenic cell death (ICD) with little or no side effect to the surrounding normal cells. Moreover, NIR-PIT can generate an immune response in distant metastases and inhibit further cancer attack by combing cancer cells targeting NIR-PIT and immune regulatory cells targeting NIR-PIT or other cancer treatment modalities. Several recent improvements in NIR-PIT have been explored such as catheter-driven NIR light delivery, real-time monitoring of cancer, and the development of new target molecule, leading to NIR-PIT being considered as a promising cancer therapy. In this review, we discuss the progress of NIR-PIT, their mechanism and design strategies for cancer treatment. Furthermore, the overall possible targeting molecules for NIR-PIT with their application for cancer treatment are briefly summarised.

Amino-OPE glycosides and blue light: a powerful synergy in photodynamic therapy

Herein we report the synthesis and biological properties of sugar-conjugated oligophenylene ethynylene (OPE) dyes, used as novel photosensitizers (PSs) for photodynamic treatment (PDT) under blue light. The OPE-bearing glycosides at both ends are successfully prepared by a Pd-catalyzed Sonogashira cross-coupling reaction. The live-cell imaging studies have shown that these OPE glycosides (including glucose, mannose and maltose derivatives) efficiently penetrate the cytoplasm of cultured HeLa cancer cells. No dark toxicity was observed, but upon irradiating the cells under blue light an extraordinary photodynamic effect was observed at low concentrations (10^-6-10^-8 M). The localization studies indicate that OPE-glucose 1 and OPE-mannose 2 have Golgi patterns, whereas OPE-maltose 3 could be in lysosomes. The PDT and morphological studies in HeLa cells treated with sublethal doses of PS 1-3 revealed that cell death occurs by necrosis.

Fluorescence probes for lung carcinoma diagnosis and clinical application

This review provides an overview of the most recent developments in fluorescence probe technology for the accurate detection and clinical therapy of lung carcinoma.

Near-infrared photoimmunotherapy: design and potential applications for cancer treatment and beyond

Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed cancer treatment modality based on a target-specific photosensitizer conjugate (TSPC) composed of an NIR phthalocyanine photosensitizer and an antigen-specific recognition system. NIR-PIT has predominantly been used for targeted therapy of tumors via local irradiation with NIR light, following binding of TSPC to antigen-expressing cells. Physical stress-induced membrane damage is thought to be a major mechanism underlying NIR-PIT-triggered photokilling. Notably, NIR-PIT can rapidly induce immunogenic cell death and activate the adaptive immune response, thereby enabling its combination with immune checkpoint inhibitors. Furthermore, NIR-PIT-triggered “super-enhanced permeability and retention” effects can enhance drug delivery into tumors. Supported by its potential efficacy and safety, NIR-PIT is a rapidly developing therapeutic option for various cancers. Hence, this review seeks to provide an update on the (i) broad range of target molecules suitable for NIR-PIT, (ii) various types of receptor-selective ligands for designing the TSPC “magic bullet,” (iii) NIR light parameters, and (iv) strategies for enhancing the efficacy of NIR-PIT. Moreover, we review the potential application of NIR-PIT, including the specific design and efficacy in 19 different cancer types, and its clinical studies. Finally, we summarize possible NIR-PIT applications in noncancerous conditions, including infection, pain, itching, metabolic disease, autoimmune disease, and tissue engineering.

Near-Infrared Photoimmunotherapy for Thoracic Cancers: A Translational Perspective

The conventional treatment of thoracic tumors includes surgery, anticancer drugs, radiation, and cancer immunotherapy. Light therapy for thoracic tumors has long been used as an alternative; conventional light therapy also called photodynamic therapy (PDT) has been used mainly for early-stage lung cancer. Recently, near-infrared photoimmunotherapy (NIR-PIT), which is a completely different concept from conventional PDT, has been developed and approved in Japan for the treatment of recurrent and previously treated head and neck cancer because of its specificity and effectiveness. NIR-PIT can apply to any target by changing to different antigens. In recent years, it has become clear that various specific and promising targets are highly expressed in thoracic tumors. In combination with these various specific targets, NIR-PIT is expected to be an ideal therapeutic approach for thoracic tumors. Additionally, techniques are being developed to further develop NIR-PIT for clinical practice. In this review, NIR-PIT is introduced, and its potential therapeutic applications for thoracic cancers are described.

Intercellular adhesion molecule-1 (ICAM-1)-targeted near-infrared photoimmunotherapy of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer and conventional chemotherapy and molecular-targeted therapies show limited efficacy. Near-infrared photoimmunotherapy (NIR-PIT) is a new anti-cancer treatment that selectively damages the cell membrane of cancer cells based on NIR light-induced photochemical reactions of the antibody-photoabsorber (IRDye700Dx) conjugate and the cell membrane. TNBC is known to express several adhesion molecules on the cell surface providing a potential new target for therapy. Here, we investigated the therapeutic efficacy of Intercellular adhesion molecule-1 (ICAM-1)-targeted NIR-PIT using xenograft mouse models subcutaneously inoculated with two human ICAM-1-expressing TNBC cell lines MDAMB468-luc and MDAMB231 cells. In vitro ICAM-1-targeted NIR-PIT damaged both cell types in a light dose-dependent manner. In vivo ICAM-1-targeted NIR-PIT in both models showed early histological signs of cancer cell damage such as cytoplasmic vacuolation. Even among the cancer cells that appeared to be morphologically intact within 2 hours post treatment, abnormal distribution of the actin cytoskeleton and a significant decrease in Ki-67 positivity were observed, indicating widespread cellular injury reflected in cytoplasmic degeneration. Such damage to cancer cells by NIR-PIT significantly inhibited subsequent tumor growth and improved survival. This study suggests that ICAM-1-targeted NIR-PIT may have potential clinical application in the treatment of TNBC.

Near-Infrared Photoimmunotherapy (NIR-PIT) in Urologic Cancers

Near-infrared photoimmunotherapy (NIR-PIT) is a novel molecularly-targeted therapy that selectively kills cancer cells by systemically injecting an antibody-photoabsorber conjugate (APC) that binds to cancer cells, followed by the application of NIR light that drives photochemical transformations of the APC. APCs are synthesized by selecting a monoclonal antibody that binds to a receptor on a cancer cell and conjugating it to IRDye700DX silica-phthalocyanine dye. Approximately 24 h after APC administration, NIR light is delivered to the tumor, resulting in nearly-immediate necrotic cell death of cancer cells while causing no harm to normal tissues. In addition, NIR-PIT induces a strong immunologic effect, activating anti-cancer immunity that can be further boosted when combined with either immune checkpoint inhibitors or immune suppressive cell-targeted (e.g., regulatory T cells) NIR-PIT. Currently, a global phase III study of NIR-PIT in recurrent head and neck squamous cell carcinoma is ongoing. The first APC and NIR laser systems were approved for clinical use in September 2020 in Japan. In the near future, the clinical applications of NIR-PIT will expand to other cancers, including urologic cancers. In this review, we provide an overview of NIR-PIT and its possible applications in urologic cancers.

Targeted photoimmunotherapy for cancer

Photodynamic therapy (PDT) is a clinically approved procedure that can exert a curative action against malignant cells. The treatment implies the administration of a photoactive molecular species that, upon absorption of visible or near infrared light, sensitizes the formation of reactive oxygen species. These species are cytotoxic and lead to tumor cell death, damage vasculature, and induce inflammation. Clinical investigations demonstrated that PDT is curative and does not compromise other treatment options. One of the major limitations of the original method was the low selectivity of the photoactive compounds for malignant over healthy tissues. The development of conjugates with antibodies has endowed photosensitizing molecules with targeting capability, so that the compounds are delivered with unprecedented precision to the site of action. Given their fluorescence emission capability, these supramolecular species are intrinsically theranostic agents.

Bioluminescence Imaging for Evaluation of Antitumor Effect In Vitro and In Vivo in Mice Xenografted Tumor Models

Bioluminescence imaging (BLI) enables real-time imaging in vitro and in vivo; it is widely used in laboratories. In vitro, the bioluminescence is commonly used as a reporter for the transfection. In vivo, BLI is employed to evaluate cell expression, migration, and proliferation inside animal bodies and visualize specific cells in various fields. Here, this chapter introduces BLI protocols for assaying the efficacy of in vivo BLI in monitoring cancer treatment using mice orthotopic models.

Orthotopic Breast Cancer Model to Investigate the Therapeutic Efficacy of Nanobody-Targeted Photodynamic Therapy

Photodynamic therapy (PDT) is characterized by the local application of laser light, which activates a photosensitizer to lead to the formation of singlet oxygen and other toxic reactive oxygen species, to finally kill cells. Recently, photosensitizers have been conjugated to nanobodies to render PDT more selective to cancer cells. Nanobodies are the smallest naturally derived antibody fragments from heavy-chain antibodies that exist in animals of the Camelidae family. Indeed, we have shown that nanobody-targeted PDT can lead to extensive and selective tumor damage, and thus the subsequent step is to assess whether this damage can delay or even inhibit tumor growth in vivo. To evaluate the therapeutic efficacy of PDT, mouse models are mostly employed in which human tumors are grown subcutaneously in the flank of the animals. Although very useful, it has been suggested that these tumors are further away from their natural environment and that tumors developed in the organ or tissue of origin would be closer to the natural situation. Thus, this chapter describes the development of an orthotopic model of breast cancer and the application of nanobody-targeted PDT, for the assessment of the therapeutic efficacy.

Near-infrared photoimmunotherapy for the treatment of skin disorders

INTRODUCTION

Near-Infrared Photoimmunotherapy (NIR-PIT) is a novel molecularly targeted phototherapy. This technique is based on a conjugate of a near-infrared photo-inducible molecule (antibody-photon absorber conjugate, APC) and a monoclonal antibody that targets a tumor-specific antigen. To date, this novel approach has been successfully applied to several types of cancer.

AREAS COVERED

The authors discuss the possible use of NIR-PIT for the management of skin diseases, with special attention given to squamous cell carcinomas, advanced melanomas, and primary cutaneous lymphomas.

EXPERT OPINION

NIR-PIT may be an attractive strategy for the treatment of skin disorders. The main advantage of NIR-PIT therapy is its low toxicity to healthy tissues. Cutaneous lymphocyte antigen is a potential molecular target for NIR-PIT for both cutaneous T-cell lymphomas and inflammatory skin disorders.

Spatiotemporal depletion of tumor-associated immune checkpoint PD-L1 with near-infrared photoimmunotherapy promotes antitumor immunity

Background

Near-infrared photoimmunotherapy (NIR-PIT) is a new modality for treating cancer, which uses antibody-photoabsorber (IRDye700DX) conjugates that specifically bind to target tumor cells. This conjugate is then photoactivated by NIR light, inducing rapid necrotic cell death. NIR-PIT needs a highly expressed targeting antigen on the cells because of its reliance on antibodies. However, using antibodies limits this useful technology to only those patients whose tumors express high levels of a specific antigen. Thus, to propose an alternative strategy, we modified this phototechnology to augment the anticancer immune system by targeting the almost low-expressed immune checkpoint molecules on tumor cells.

Methods

We used programmed death-ligand 1 (PD-L1), an immune checkpoint molecule, as the target for NIR-PIT. Although the expression of PD-L1 on tumor cells is usually low, PD-L1 is almost expressed on tumor cells. Intratumoral depletion with PD-L1-targeted NIR-PIT was tested in mouse syngeneic tumor models.

Results

Although PD-L1-targeted NIR-PIT showed limited effect on tumor cells in vitro, the therapy induced sufficient antitumor effects in vivo, which were thought to be mediated by the ‘photoimmuno’ effect and antitumor immunity augmentation. Moreover, PD-L1-targeted NIR-PIT induced antitumor effect on non-NIR light-irradiated tumors.

Conclusions

Local PD-L1-targeted NIR-PIT enhanced the antitumor immune reaction through a direct photonecrotic effect, thereby providing an alternative approach to targeted cancer immunotherapy and expanding the scope of cancer therapeutics.

HER2 targeting near-infrared photoimmunotherapy for a CDDP-resistant small-cell lung cancer

Background

Human epidermal growth factor receptor 2 (HER2) is tyrosine kinase receptor that belongs to the ErbB family and is overexpressed on the membrane surface of various cancer cells, including small cell lung cancer (SCLC); however, no HER2 targeted therapy for SCLC have yet been established. Near‐infrared photoimmunotherapy (NIR‐PIT) is a novel cancer therapy based on photo‐absorber, IRDye‐700DX (IR700), ‐antibody conjugates, and near‐infrared (NIR) light.

Methods

We used HER2‐positive SCLC parental cell lines (SBC‐3) and its chemoresistant cell lines, and examined therapeutic efficacy of HER2 targeting NIR‐PIT using anti HER2 antibody trastuzumab.

Results

We found that HER2 expression was upregulated on chemoresistant cell lines, especially cisplatin‐resistance (SBC‐3/CDDP). In vitro, the rate of cell death increased with the amount of NIR‐light irradiation, and it was significantly higher in SBC‐3/CDDP than in SBC‐3. In vivo, tumor growth was more suppressed in SBC‐3/CDDP group than in SBC‐3 group, and survival period tended to be prolonged.

Conclusion

In this study, we demonstrated that HER2 targeting NIR‐PIT using trastuzumab is promising therapy for HER2‐positive SCLC, and is more effective when HER2 expression is upregulated due to CDDP resistance, suggesting that the HER2 expression level positively corelated with the efficacy of NIR‐PIT.

Hurdles for the wide implementation of photoimmunotherapy

Near infrared photoimmunotherapy (NIR-PIT) is a molecularly targeted treatment for cancers achieved by injecting a conjugate of IRDye700DX^® (IR700), a water-soluble silicon phthalocyanine derivative in the near infrared, and a monoclonal antibody that targets cancer cell antigens. NIR-PIT is a highly specific treatment with few side effects that results in rapid immunogenic cell death. Despite it being a very effective and innovative therapy, there are a few challenges preventing full implementation in clinical practice. These include the limits of near infrared light penetration, selection of targets, concerns about tumor lysis syndrome and drug costs. However, NIR-PIT has been approved by the regulatory authorities in Japan, allowing for exploration of how to mitigate challenges while maximizing the benefits of this treatment modality.

Local biomaterial-assisted antitumour immunotherapy for effusions in the pleural and peritoneal cavities caused by malignancies

Malignant pleural effusion (MPE) and malignant ascites (MA), which are common but serious conditions caused by malignancies, are related to poor quality of life and high mortality. Current treatments, including therapeutic thoracentesis and indwelling pleural catheters or paracentesis and catheter drainage, are largely palliative. An effective treatment is urgently needed. MPE and MA are excellent candidates for intratumoural injections that have direct contact with tumour cells and kill tumour cells more effectively and efficiently with fewer side effects, and the fluid environment of MPE and MA can provide a homogeneous area for drug distribution. The immunosuppressive environments within the pleural and peritoneal cavities suggest the feasibility of local immunotherapy. In this review, we introduce the current management of MPE and MA, discuss the latest advances and challenges in utilizing local biomaterial-assisted antitumour therapies for the treatment of MPE and MA, and discuss further opportunities in this field.

Simultaneous exposure to intracellular and extracellular photosensitizers for the treatment of Staphylococcus aureus infections

Staphylococcus aureus is a serious threat to public health due to the rise of antibiotic resistance in this organism, which can prolong or exacerbate skin and soft tissue infections (SSTIs). Methicillin-resistant S. aureus is a Gram-positive bacterium and a leading cause of SSTIs. As such, many efforts are underway to develop therapies that target essential biological processes in S. aureus. Antimicrobial photodynamic therapy is effective alternative to antibiotics, therefore we developed an approach to simultaneously expose S. aureus to intracellular and extracellular photoactivators. A near infrared photosensitizer was conjugated to human monoclonal antibodies (mAbs) that target the S. aureus Isd heme acquisition proteins. Additionally, the compound VU0038882 was developed to increase photoactivatable porphyrins within the cell. Combinatorial PDT treatment of drug-resistant S. aureus exposed to VU0038882 and conjugated anti-Isd mAbs proved to be an effective antibacterial strategy in vitro and in a murine model of SSTIs.

Near infrared photoimmunotherapy of cancer; possible clinical applications

Near-infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that uses an antibody-photo-absorber conjugate (APC) composed of a targeting monoclonal antibody conjugated with a photoactivatable phthalocyanine-derivative dye, IRDye700DX (IR700). APCs injected into the body can bind to cancer cells where they are activated by local exposure to NIR light typically delivered by a NIR laser. NIR light alters the APC chemical conformation inducing damage to cancer cell membranes, resulting in necrotic cell death within minutes of light exposure. NIR-PIT selectivity kills cancer cells by immunogenic cell death (ICD) with minimal damage to adjacent normal cells thus, leading to rapid recovery by the patient. Moreover, since NIR-PIT induces ICD only on cancer cells, NIR-PIT initiates and activates antitumor host immunity that could be further enhanced when combined with immune checkpoint inhibition. NIR-PIT induces dramatic changes in the tumor vascularity causing the super-enhanced permeability and retention (SUPR) effect that dramatically enhances nanodrug delivery to the tumor bed. Currently, a worldwide Phase 3 study of NIR-PIT for recurrent or inoperable head and neck cancer patients is underway. In September 2020, the first APC and accompanying laser system were conditionally approved for clinical use in Japan. In this review, we introduce NIR-PIT and the SUPR effect and summarize possible applications of NIR-PIT in a variety of cancers.

Near Infrared Photoimmunotherapy; A Review of Targets for Cancer Therapy

Simple Summary

Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed cancer treatment that uses an antibody-photoabsorber (IRDye700DX) conjugate (APC) that is activated by NIR light irradiation. A major benefit of NIR-PIT is that only APC-bound cancer cells that are exposed to NIR light are killed by NIR-PIT; thus, minimal damage occurs in adjacent normal cells. NIR-PIT has now been applied to many cancers expressing various cell-surface target proteins using monoclonal antibodies designed to bind to them. Moreover, NIR-PIT is not limited to tumor antigens but can also be used to kill specific host cells that create immune-permissive environments in which tumors grow. Moreover, multiple targets can be treated simultaneously with NIR-PIT using a cocktail of APCs. NIR-PIT has great potential to treat a wide variety of cancers by targeting appropriate tumor cells, immune cells, or both, and can be augmented by other immunotherapies.

Abstract

Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed cancer treatment that uses an antibody-photoabsorber (IRDye700DX) conjugate (APC) that is activated by NIR light irradiation. In September 2020, the first APC and laser system were conditionally approved for clinical use in Japan. A major benefit of NIR-PIT is that only APC-bound cancer cells that are exposed to NIR light are killed by NIR-PIT; thus, minimal damage occurs in adjacent normal cells. These early trials have demonstrated that in addition to direct cell killing, there is a significant therapeutic host immune response that greatly contributes to the success of the therapy. Although the first clinical use of NIR-PIT targeted epidermal growth factor receptor (EGFR), many other targets are suitable for NIR-PIT. NIR-PIT has now been applied to many cancers expressing various cell-surface target proteins using monoclonal antibodies designed to bind to them. Moreover, NIR-PIT is not limited to tumor antigens but can also be used to kill specific host cells that create immune-permissive environments in which tumors grow. Moreover, multiple targets can be treated simultaneously with NIR-PIT using a cocktail of APCs. NIR-PIT can be used in combination with other therapies, such as immune checkpoint inhibitors, to enhance the therapeutic effect. Thus, NIR-PIT has great potential to treat a wide variety of cancers by targeting appropriate tumor cells, immune cells, or both, and can be augmented by other immunotherapies.

Near-infrared photoimmunotherapy targeting GPR87: Development of a humanised anti-GPR87 mAb and therapeutic efficacy on a lung cancer mouse model

BACKGROUND

GPR87 is a G-protein receptor that is specifically expressed in tumour cells, such as lung cancer, and rarely expressed in normal cells. GPR87 is a promising target for cancer therapy, but its ligand is controversial. Near-infrared photoimmunotherapy (NIR-PIT) is a novel cancer therapy in which a photosensitiser, IRDye700DX (IR700), binds to antibodies and specifically destroys target cells by irradiating them with near-infrared-light. Here, we aimed to develop a NIR-PIT targeting GPR87.

METHODS

We evaluated the expression of GPR87 in resected specimens of lung cancer and malignant pleural mesothelioma (MPM) resected at Nagoya University Hospital using immunostaining. Humanised anti-GPR87 antibody (huGPR87) was generated by introducing CDRs from mouse anti-GPR87 antibody generated by standard hybridoma method. HuGPR87 was conjugated with IR700 and the therapeutic effect of NIR-PIT was evaluated in vitro and in vivo using lung cancer or MPM cell lines.

FINDINGS

Among the surgical specimens, 54% of lung cancer and 100% of MPM showed high expression of GPR87. It showed therapeutic effects on lung cancer and MPM cell lines in vitro, and showed therapeutic effects in multiple models in vivo.

INTERPRETATION

These results suggest that NIR-PIT targeting GPR87 is a promising therapeutic approach for the treatment of thoracic cancer.

FUNDING

This research was supported by the Program for Developing Next-generation Researchers (Japan Science and Technology Agency), KAKEN (18K15923, 21K07217, JSPS), FOREST-Souhatsu, CREST (JST).

Near-InfraRed PhotoImmunoTherapy (NIR-PIT) for the local control of solid cancers: Challenges and potentials for human applications

Near-InfraRed PhotoImmunoTherapy (NIR-PIT) is a novel cancer-targeted treatment effected by a chemical conjugation between a photosensitiser (e.g. the NIR phthalocyanine dye IRDye700DX) and a cancer-targeting moiety (e.g. a monoclonal antibody, moAb). Delivery of a conjugate in vivo leads to accumulation at the tumour cell surface by binding to cell surface receptors or antigens. Upon deployment of focal NIR-light, irradiation of the conjugate results in a rapid, targeted cell death. However, the mechanisms of action to produce the cytotoxic effects have yet to be fully understood. Herein, we bring together the current knowledge of NIR-PIT from preclinical and clinical studies in a variety of cancers highlighting the key unanswered research questions. Furthermore, we discuss how to enhance the local control of solid cancers using this novel treatment regimen.

Near-infrared photoimmunotherapy of cancer: a new approach that kills cancer cells and enhances anti-cancer host immunity

Near-infrared photoimmunotherapy (NIR-PIT) is a recently developed hybrid cancer therapy that directly kills cancer cells as well as producing a therapeutic host immune response. Conventional immunotherapies, such as immune-activating cytokine therapy, checkpoint inhibition, engineered T cells and suppressor cell depletion, do not directly destroy cancer cells, but rely exclusively on activating the immune system. NIR-PIT selectively destroys cancer cells, leading to immunogenic cell death that initiates local immune reactions to released cancer antigens from dying cancer cells. These are characterized by rapid maturation of dendritic cells and priming of multi-clonal cancer-specific cytotoxic T cells that kill cells that escaped the initial direct effects of NIR-PIT. The NIR-PIT can be applied to a wide variety of cancers either as monotherapy or in combination with conventional immune therapies to further activate anti-cancer immunity. A global Phase 3 clinical trial (https://clinicaltrials.gov/ct2/show/NCT03769506) of NIR-PIT targeting the epidermal growth factor receptor (EGFR) in patients with recurrent head and neck cancer is underway, employing RM1929/ASP1929, a conjugate of anti-EGFR antibody (cetuximab) plus the photo-absorber IRDye700DX (IR700). NIR-PIT has been given fast-track recognition by regulators in the USA and Japan. A variety of imaging methods, including direct IR700 fluorescence imaging, can be used to monitor NIR-PIT. As experience with NIR-PIT grows, additional antibodies will be employed to target additional antigens on other cancers or to target immune-suppressor cells to enhance host immunity. NIR-PIT will be particularly important in patients with localized and locally advanced cancers and may help such patients avoid side-effects associated with surgery, radiation and chemotherapy.

Cancer photo-immunotherapy: from bench to bedside

Targeted therapy and immunotherapy in combination is considered the ideal strategy for treating metastatic cancer, as it can eliminate the primary tumors and induce host immunity to control distant metastases. Phototherapy, a promising targeted therapy, eradicates primary tumors using an appropriate dosage of focal light irradiation, while initiating antitumor immune responses through induced immunogenic tumor cell death. Recently, phototherapy has been employed to improve the efficacy of immunotherapies such as chimeric antigen receptor T-cell therapy and immune checkpoint inhibitors. Phototherapy and immunoadjuvant therapy have been used in combination clinically, wherein the induced immunogenic cell death and enhanced antigen presentation synergy, inducing a systemic antitumor immune response to control residual tumor cells at the treatment site and distant metastases. This review summarizes studies on photo-immunotherapy, the combination of phototherapy and immunotherapy, especially focusing on the development and progress of this unique combination from a benchtop project to a promising clinical therapy for metastatic cancer.

The feasibility of Miltuximab®-IRDye700DX-mediated photoimmunotherapy of solid tumors

BACKGROUND

Photoimmunotherapy (PIT) is an emerging method of cancer treatment based on the use of a photosensitizer near-infrared dye IRDye700DX (IR700) conjugated to a monoclonal antibody. The antibody selectively delivers IR700 to cancer cells, which can then be killed after photoexcitation. Glypican-1 (GPC-1) is a novel target expressed specifically in malignant tumors. We aimed to investigate whether anti-GPC-1 antibody Miltuximab® (Glytherix Ltd., Sydney, Australia) can be conjugated with IR700 for PIT of solid tumors.

METHODS

The dye IR700 was conjugated with Miltuximab® and characterized by spectrophotometry and flow cytometry. Miltuximab®-IR700-mediated PIT was tested in prostate (DU-145), bladder (C3 and T-24), brain (U-87 and U-251) and ovarian (SKOV-3) cancer cell lines. After 1 h incubation with Miltuximab®-IR700, the cells were washed by PBS and illuminated using a 690-nm light-emitting diode. The viability of the cells was assessed by a CCK-8 viability kit 24 h later.

RESULTS

Miltuximab®-IR700-mediated PIT caused 67.3-92.3% reduction in viability of cells with medium-high GPC-1 expression and did not affect the viability of GPC-1-low cells. Cytotoxicity was attributed to the targeted binding of the conjugate with subsequent photoactivation, as the conjugate or light exposure alone had no effect on the cell viability. Miltuximab®-IR700 did not induce cytotoxicity in cells blocked by unconjugated Miltuximab®.

CONCLUSIONS

PIT with Miltuximab®-IR700 appears to be highly specific and effective against GPC-1-expressing cancer cells, indicating that it holds promise for an effective and safe treatment of early stage solid tumors or as adjuvant therapy following surgical resection. These findings necessitate further investigation of PIT with Miltuximab®-IR700 in other GPC-1-expressing cancer cell lines in vitro and in vivo in xenograft tumor models.

Interleukin-15 after Near-Infrared Photoimmunotherapy (NIR-PIT) Enhances T Cell Response against Syngeneic Mouse Tumors

Simple Summary

Near infrared photoimmunotherapy is a newly developed and highly selective cancer treatment that employs a monoclonal antibody conjugated to a photo-absorber dye, IRDye700DX, which is activated by 690 nm light. Cancer cell-targeted near infrared photoimmunotherapy selectively induces rapid necrotic/immunogenic cell death only on target cancer cells and this induces antitumor host immunity including re-priming and proliferation of multi-chronal T-cells that can react with cancer-specific antigens. Interleukin-15 is a type-I cytokine that activates natural killer-, B- and T-cells while having minimal effect on regulatory T-cells that lack the interleukin-15 receptor. Therefore, interleukin-15 administration combined with cancer cell-targeted near infrared photoimmunotherapy could further inhibit tumor growth by increasing antitumor host immunity. In tumor-bearing immunocompetent mice receiving this combination therapy, significant tumor growth inhibition and prolonged survival was demonstrated compared with either single therapy alone, and tumor infiltrating CD8+ T-cells increased in number in combination-treated mice. Interleukin-15 enhances therapeutic effects of cancer-targeted near infrared photoimmunotherapy.

Abstract

Near infrared photoimmunotherapy (NIR-PIT) is a newly developed and highly selective cancer treatment that employs a monoclonal antibody (mAb) conjugated to a photo-absorber dye, IRDye700DX, which is activated by 690 nm light. Cancer cell-targeted NIR-PIT induces rapid necrotic/immunogenic cell death (ICD) that induces antitumor host immunity including re-priming and proliferation of T cells. Interleukin-15 (IL-15) is a cytokine that activates natural killer (NK)-, B- and T-cells while having minimal effect on regulatory T cells (Tregs) that lack the IL-15 receptor. Here, we hypothesized that IL-15 administration with cancer cell-targeted NIR-PIT could further inhibit tumor growth by increasing antitumor host immunity. Three syngeneic mouse tumor models, MC38-luc, LL/2, and MOC1, underwent combined CD44-targeted NIR-PIT and short-term IL-15 administration with appropriate controls. Comparing with the single-agent therapy, the combination therapy of IL-15 after NIR-PIT inhibited tumor growth, prolonged survival, and increased tumor infiltrating CD8+ T cells more efficiently in tumor-bearing mice. IL-15 appears to enhance the therapeutic effect of cancer-targeted NIR-PIT.

Photodynamic Therapy and Immunity: An Update

Dr. Thomas Dougherty and his Oncology Foundation of Buffalo were the first to support my (S.O.G.) research into the effects of photodynamic therapy (PDT) on the host immune system. The small grant I was awarded in 2002 launched my career as an independent researcher; at the time, there were few studies on the importance of the immune response on the efficacy of PDT and no studies demonstrating the ability of PDT to enhance antitumor immunity. Over the last decades, the interest in PDT as an enhancer of antitumor immunity and our understanding of the mechanisms by which PDT enhances antitumor immunity have dramatically increased. In this review article, we look back on the studies that laid the foundation for our understanding and provide an update on current advances and therapies that take advantage of PDT enhancement of immunity.

Targeted Phototherapy for Malignant Pleural Mesothelioma: Near-Infrared Photoimmunotherapy Targeting Podoplanin

Malignant pleural mesothelioma (MPM) has extremely limited treatment despite a poor prognosis. Moreover, molecular targeted therapy for MPM has not yet been implemented; thus, a new targeted therapy is highly desirable. Near-infrared photoimmunotherapy (NIR-PIT) is a recently developed cancer therapy that combines the specificity of antibodies for targeting tumors with toxicity induced by the photoabsorber after exposure to NIR-light. In this study, we developed a new phototherapy targeting podoplanin (PDPN) for MPM with the use of both NIR-PIT and an anti-PDPN antibody, NZ-1. An antibody–photosensitizer conjugate consisting of NZ-1 and phthalocyanine dye was synthesized. In vitro NIR-PIT-induced cytotoxicity was measured with both dead cell staining and luciferase activity on various MPM cell lines. In vivo NIR-PIT was examined in both the flank tumor and orthotopic mouse model with in vivo real-time imaging. In vitro NIR-PIT-induced cytotoxicity was NIR-light dose dependent. In vivo NIR-PIT led to significant reduction in both tumor volume and luciferase activity in a flank model (p < 0.05, NIR-PIT group versus NZ-1-IR700 group). The PDPN-targeted NIR-PIT resulted in a significant antitumor effect in an MPM orthotopic mouse model (p < 0.05, NIR-PIT group versus NZ-1-IR700 group). This study suggests that PDPN-targeted NIR-PIT could be a new promising treatment for MPM.

Near infrared photoimmunotherapy targeting DLL3 for small cell lung cancer

BACKGROUND

Small cell lung cancer (SCLC) has a poor prognosis, and its treatment options are limited. Delta-like protein 3 (DLL3) is expressed specifically in SCLC and is considered a promising therapeutic target for patients with this disease. Rovalpituzumab tesirine (Rova-T) was the first antibody-drug conjugate targeting DLL3. Although Rova-T development was unfortunately terminated, DLL3 remains an ideal target for SCLC. Near infrared photoimmunotherapy (NIR-PIT) is a new form of cancer treatment that employs an antibody-photosensitiser conjugate followed by NIR light exposure and damage target cells specifically. In this study, we demonstrate DLL3-targeted NIR-PIT to develop a novel molecularly targeted treatment for SCLC.

METHODS

The anti-DLL3 monoclonal antibody rovalpituzumab was conjugated to an IR700 photosensitiser (termed 'rova-IR700'). SCLC cells overexpressing DLL3 as well as non-DLL3-expressing controls were incubated with rova-IR700 and then exposed to NIR-light. Next, mice with SCLC xenografts were injected with rova-IR700 and irradiated with NIR-light.

FINDINGS

DLL3-overexpressing cells underwent immediate destruction upon NIR-light exposure, whereas the control cells remained intact. The xenograft in mice treated with rova-IR700 and NIR-light shrank markedly, whereas neither rova-IR700 injection nor NIR-light irradiation alone affected tumour size.

INTERPRETATION

Our data suggest that targeting of DLL3 using NIR-PIT could be a novel and promising treatment for SCLC.

FUNDING

Research supported by grants from the Program for Developing Next-generation Researchers (Japan Science and Technology Agency), KAKEN (18K15923, JSPS), Medical Research Encouragement Prize of The Japan Medical Association, The Nitto Foundation, Kanae Foundation for the Promotion of Medical Science.

Acute cellular and vascular responses to photodynamic therapy using EGFR-targeted nanobody-photosensitizer conjugates studied with intravital optical imaging and magnetic resonance imaging

Targeted photodynamic therapy (PDT) has the potential to selectively damage tumor tissue and to increase tumor vessel permeability. Here we characterize the tissue biodistribution of two EGFR-targeted nanobody-photosensitizer conjugates (NB-PS), the monovalent 7D12-PS and the biparatopic 7D12-9G8-PS. In addition, we report on the local and acute phototoxic effects triggered by illumination of these NB-PS which have previously shown to lead to extensive tumor damage. Methods: Intravital microscopy and the skin-fold chamber model, containing OSC-19-luc2-cGFP tumors, were used to investigate: a) the fluorescence kinetics and distribution, b) the vascular response and c) the induction of necrosis after illumination at 1 or 24 h post administration of 7D12-PS and 7D12-9G8-PS. In addition, dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) of a solid tumor model was used to investigate the microvascular status 2 h after 7D12-PS mediated PDT. Results: Image analysis showed significant tumor colocalization for both NB-PS which was higher for 7D12-9G8-PS. Intravital imaging showed clear tumor cell membrane localization 1 and 2 h after administration of 7D12-9G8-PS, and fluorescence in or close to endothelial cells in normal tissue for both NB-PS. PDT lead to vasoconstriction and leakage of tumor and normal tissue vessels in the skin-fold chamber model. DCE-MRI confirmed the reduction of tumor perfusion after 7D12-PS mediated PDT. PDT induced extensive tumor necrosis and moderate normal tissue damage, which was similar for both NB-PS conjugates. This was significantly reduced when illumination was performed at 24 h compared to 1 h after administration. Discussion: Although differences were observed in distribution of the two NB-PS conjugates, both led to similar necrosis. Clearly, the response to PDT using NB-PS conjugates is the result of a complex mixture of tumor cell responses and vascular effects, which is likely to be necessary for a maximally effective treatment.

Near-Infrared Photoimmunotherapy: Photoactivatable Antibody-Drug Conjugates (ADCs)

Cancer treatment has been founded traditionally on the three approaches of surgery, radiation, and chemotherapy with the latter recognized as the obvious systemic treatment approach applicable to disease that has spread. Although significant progress has been made over nearly 100 years of developing systemic treatments, it remains clear that use of the toxic agents involved is a two-edged sword with normal organ toxicities always needing to be balanced with and against administration of relevant therapeutic doses. With the advent of monoclonal antibodies targeted against tumor-associated antigens that could be used as carriers of potently toxic chemotherapy drugs, it was thought that such antibody-drug conjugates (ADCs) could engender the answer to the toxicity/therapeutic equation by shifting the equation more toward beneficial therapeutic efficacy. However, over 40 or so years, antibody-drug conjugates have not significantly affected the toxicity/therapy balance paradigm in most cancer indications, especially in solid tumors. Ideally, a further step may be required in that a non-tumor-targeted antibody-drug conjugate should be essentially nontoxic in its native administered form, with toxic effects unleashed only at the site of targeted tumors. A new approach that employs this principle is the use of an antibody-drug conjugate that is essentially nontoxic to normal tissues by virtue of requiring an extra step of light activation to become potent. We describe the preclinical data and first clinical results gained over the past few years by use of antibody-drug conjugates wherein the drug comprises a near-infrared photoactivatable dye delivered to tumors by a monoclonal antibody and is subsequently activated to a toxic entity solely at sites of tumors.

Cancer neovasculature-targeted near-infrared photoimmunotherapy (NIR-PIT) for gastric cancer: different mechanisms of phototoxicity compared to cell membrane-targeted NIR-PIT

BACKGROUND

Near-infrared photoimmunotherapy (NIR-PIT) constitutes a new class of molecular-targeted theranostics utilizing monoclonal antibody (mAb)-photosensitizer conjugates and NIR light. In this study, we developed a new type of NIR-PIT targeting vascular endothelial growth factor receptor 2 (VEGFR-2) expressed on vascular endothelium in an experimental gastric cancer model and evaluated the feasibility by comparing conventional NIR-PIT targeting cancer cell membrane in vitro and in vivo.

METHODS

HER2-positive human gastric cancer cells, NCI-N87, were used for the experiments. Anti-HER2 mAb, trastuzumab and anti-VEGFR-2 mAb, DC101 were conjugated to photosensitizer, IR700. Phototoxicity in response to NIR-PIT were investigated in vitro and in vivo. Microvessel densities, as an indicator of angiogenesis, were counted in harvested xenografts after NIR-PIT to elucidate the mechanism.

RESULTS

DC101-IR700 did not induce phototoxic effect in vitro because of the absence of expression of VEGFR-2 in NCI-N87 cancer cells. However, it induced an antitumor effect in NCI-N87 xenograft tumors accompanied with damage in tumor neovasculature as determined by decreasing tumor microvessel density, which represents a different mechanism than that of conventional NIR-PIT targeting antigens expressed on the tumor cell membrane.

CONCLUSION

We demonstrated a new approach of NIR-PIT utilizing a target on vascular endothelium, such as VEGFR-2, and this treatment might lead to the development of a new therapeutic strategy for human gastric cancer.

Neutrophil infiltration and whole-cell vaccine elicited by N-dihydrogalactochitosan combined with NIR phototherapy to enhance antitumor immune response and T cell immune memory

Melanoma is one of the deadliest malignancies with a high risk of relapse and metastasis. Long-term, tumor-specific, and systemic immunity induced by local intervention is ideal for personalized cancer therapy. Laser immunotherapy (LIT), a combination of local irradiation of laser and local administration of an immunostimulant, was developed to achieve such an immunity. Although LIT showed promising efficacy on tumors, its immunological mechanism is still not understood, especially its spatio-temporal dynamics.

Methods: In this study, we investigated LIT-induced immunological responses using a 980-nm laser and a novel immunostimulant, N-dihydrogalactochitosan (GC). Then we followed the functions of key immune cells spatially and temporally using intravital imaging and immunological assays.

Results: Immediately after LIT, GC induced a rapid infiltration of neutrophils which ingested most GC in tumors. The cytokines released to the serum peaked at 12 h after LIT. Laser irradiations produced photothermal effects to ablate the tumor, release damage-associated molecular patterns, and generate whole-cell tumor vaccines. LIT-treated tumor-bearing mice efficiently resisted the rechallenged tumor and prevented lung metastasis. Intravital imaging of tumor at rechallenging sites in LIT-treated mice revealed that the infiltration of tumor-infiltrating lymphocytes (TILs) increased with highly active motility. Half of TILs with arrest and confined movements indicated that they had long-time interactions with tumor cells. Furthermore, LIT has synergistic effect with checkpoint blockade to improve antitumor efficacy.

Conclusion: Our research revealed the important role of LIT-induced neutrophil infiltration on the in situ whole-cell vaccine-elicited antitumor immune response and long-term T cell immune memory.

Near-Infrared Photoimmunotherapy of Cancer

This Account is the first comprehensive review article on the newly developed, photochemistry-based cancer therapy near-infrared (NIR) photoimmunotherapy (PIT). NIR-PIT is a molecularly targeted phototherapy for cancer that is based on injecting a conjugate of a near-infrared, water-soluble, silicon-phthalocyanine derivative, IRdye700DX (IR700), and a monoclonal antibody (mAb) that targets an expressed antigen on the cancer cell surface. Subsequent local exposure to NIR light turns on this photochemical "death" switch, resulting in the rapid and highly selective immunogenic cell death (ICD) of targeted cancer cells. ICD occurs as early as 1 min after exposure to NIR light and results in irreversible morphologic changes only in target-expressing cells based on the newly discovered photoinduced ligand release reaction that induces physical changes on conjugated antibody/antigen complex resulting in functional damage on cell membrane. Meanwhile, immediately adjacent receptor-negative cells are totally unharmed. Because of its highly targeted nature, NIR-PIT carries few side effects and healing is rapid. Evaluation of the tumor microenvironment reveals that ICD induced by NIR-PIT results in rapid maturation of immature dendritic cells adjacent to dying cancer cells initiating a host anticancer immune response, resulting in repriming of polyclonal CD8⁺T cells against various released cancer antigens, which amplifies the therapeutic effect of NIR-PIT. NIR-PIT can target and treat virtually any cell surface antigens including cancer stem cell markers, that is, CD44 and CD133. A first-in-human phase 1/2 clinical trial of NIR-PIT using cetuximab-IR700 (RM1929) targeting EGFR in inoperable recurrent head and neck cancer patients successfully concluded in 2017 and led to "fast tracking" by the FDA and a phase 3 trial ( https://clinicaltrials.gov/ct2/show/NCT03769506 ) that is currently underway in 3 countries in Asia, US/Canada, and 4 countries in EU. The next step for NIR-PIT is to further exploit the immune response. Preclinical research in animals with intact immune systems has shown that NIT-PIT targeting of immunosuppressor cells within the tumor, such as regulatory T-cells, can further enhance tumor-cell-selective systemic host-immunity leading to significant responses in distant metastatic tumors, which are not treated with light. By combining cancer-targeting NIR-PIT and immune-activating NIR-PIT or other cancer immunotherapies, NIR-PIT of a local tumor, could lead to responses in distant metastases and may also inhibit recurrences due to activation of systemic anticancer immunity and long-term immune memory without the systemic autoimmune adverse effects often associated with immune checkpoint inhibitors. Furthermore, NIR-PIT also enhances nanodrug delivery into tumors up to 24-fold superior to untreated tumors with conventional EPR effects by intensively damaging cancer cells behind tumor vessels. We conclude by describing future advances in this novel photochemical cancer therapy that are likely to further enhance the efficacy of NIR-PIT.

Photoimmunoconjugates: novel synthetic strategies to target and treat cancer by photodynamic therapy

Photodynamic therapy (PDT) combines a photosensitizer (PS) with the physical energy of non-ionizing light to trigger cell death pathways. PDT has potential as a therapeutic modality to be used in alternative or in combination with other conventional cancer treatment protocols (e.g. surgery, chemotherapy and radiotherapy). Still, due to the lack of specificity of the current PSs to target the tumor cells, several studies have exploited their conjugation with targeting moieties. PSs conjugated with antibodies (Abs) or their fragments, able to bind antigens overexpressed in the tumors, have demonstrated potential in PDT of tumors. This review provides an overview of the most recent advances on photoimmunoconjugates (PICs) for cancer PDT, which involve the first and second-generation PSs conjugated to Abs. This is an update of our previous review "Antibodies armed with photosensitizers: from chemical synthesis to photobiological applications", published in 2015 in Org. Biomol. Chem.

Near infrared photoimmunotherapy using a fiber optic diffuser for treating peritoneal gastric cancer dissemination

BACKGROUND

Peritoneal dissemination (PD) of abdominal malignancies is a common form of metastasis and its presence signals a poor prognosis. New treatment is required for patients with PD. Near infrared photoimmunotherapy (NIR-PIT) is a highly selective tumor treatment that employs an antibody-photo-absorber conjugate (APC). In this study, we investigate in vitro and in vivo efficacy of trastuzumab (tra)-IR700DX NIR-PIT on a human epidermal growth factor receptor type 2 (HER2)-positive gastric cancer cell line.

METHODS

NIR-PIT effects were investigated in vitro and in vivo. Disseminated peritoneal implants mice were separated into 5 groups: (1) no treatment; (2) tra-IR700 i.v. only; (3) NIR light only; (4) NIR-PIT; (5) repeated NIR-PIT. The peritoneal cavity was irradiated with NIR light using a fiber optic diffuser delivered through the catheter.

RESULTS

Specific binding and cell-specific killing was observed after NIR-PIT in vitro. In the in vivo study, fluorescence endoscopy showed high tumor accumulation of tra-IR700 within tumors. Significantly prolonged survival was achieved in the three treatment groups (tra-IR700 i.v. only, NIR-PIT, and repeated NIR-PIT groups) compared with control and NIR light only group (p < 0.05 for tra-IR700 i.v. only, p < 0.01 for NIR-PIT, and p < 0.0001 for repeated NIR-PIT). Moreover, most prolonged survival was shown for the repeated NIR-PIT group (p < 0.0001 vs tra-IR700 i.v. only, p < 0.01 vs NIR-PIT).

CONCLUSION

NIR-PIT using a fiber optic diffuser to deliver light is a promising candidate for the treatment of disseminated peritoneal metastases and could be readily translated to humans.

Cell Internalization in Fluidic Culture Conditions Is Improved When Microparticles Are Specifically Targeted to the Human Epidermal Growth Factor Receptor 2 (HER2)

Purpose: To determine if the specific targeting of microparticles improves their internalization by cells under fluidic conditions. Methods: Two isogenic breast epithelial cell lines, one overexpressing the Human Epidermal Growth Factor Receptor 2 (HER2) oncogene (D492HER2) and highly tumorigenic and the other expressing HER2 at much lower levels and non-tumorigenic (D492), were cultured in the presence of polystyrene microparticles of 1 µm in diameter, biofunctionalized with either a specific anti-HER2 antibody or a non-specific secondary antibody. Mono- and cocultures of both cell lines in static and fluidic conditions were performed, and the cells with internalized microparticles were scored. Results: Globally, the D492 cell line showed a higher endocytic capacity than the D492HER2 cell line. Microparticles that were functionalized with the anti-HER2 antibody were internalized by a higher percentage of cells than microparticles functionalized with the non-specific secondary antibody. Although internalization was reduced in fluidic culture conditions in comparison with static conditions, the increase in the internalization of microparticles biofunctionalized with the anti-HER2 antibody was higher for the cell line overexpressing HER2. Conclusion: The biofunctionalization of microparticles with a specific targeting molecule remarkably increases their internalization by cells in fluidic culture conditions (simulating the blood stream). This result emphasizes the importance of targeting for future in vivo delivery of drugs and bioactive molecules through microparticles.

Human epidermal growth factor receptor 2-, epidermal growth factor receptor-, and mesenchymal epithelial transition factor-positive sites of gastric cancer using surgical samples

BACKGROUND

Receptor tyrosine kinases (RTKs) play critical roles in gastric cancer (GC) progression and are potential targets for novel molecular-targeted agents or photo-immunotherapies. During patient selection, targeted biopsy is the first step. However, heterogeneous expression of RTKs based on the macroscopic appearance in GC has not been extensively addressed. Accordingly, in this study, we evaluated differences in RTK expression associated with macroscopic appearance in GC.

METHODS

In total, 375 consecutive patients who had undergone gastrectomy at the National Cancer Center Hospital East and who had histologically proven adenocarcinoma, available archived tumor sample, and no history of chemotherapy were enrolled in this study. For these cases, tissue microarray (TMA) samples were examined using immunohistochemistry (IHC). Based on the results of IHC, cases were selected for detailed examination. We re-evaluated IHC scores in more than three tumor blocks per case and comparatively evaluated differences in IHC expression in RTKs between the mucosal portion (MuP) and invasive portion (InP).

RESULTS

Human epidermal growth factor receptor 2 (HER2)-, epidermal growth factor receptor (EGFR)-, and mesenchymal epithelial transition factor (c-MET)-positive rates were 6, 9, and 20%, respectively. Twenty-two cases were then analyzed to assess differences in IHC expression levels in the same lesion. Concordance rates of positive staining of HER2, EGFR, and MET between MuP and whole tumor were 100, 40, and 56% and those with InP were 46, 100, and 56%.

CONCLUSIONS

To avoid underestimating expression status, biopsies must be taken from MuP for HER2, InP for EGFR, and both proportions for c-MET.

Tumour-targeting photosensitisers for one- and two-photon activated photodynamic therapy

Efficient receptor-mediated delivery of a folate-targeted photosensitiser to kill cancer cells following two-photon excitation in the near-infrared is demonstrated.

Enhancing Anti-PD-1/PD-L1 Immune Checkpoint Inhibitory Cancer Therapy by CD276-Targeted Photodynamic Ablation of Tumor Cells and Tumor Vasculature

Antiangiogenic therapies have been demonstrated to improve the efficacy of immune checkpoint inhibition by overcoming the immunosuppressive status of the tumor microenvironment. However, most of the current antiangiogenic agents cannot discriminate tumor angiogenesis from physiological angiogenesis. The aim of this study was to investigate whether a photodynamic therapy (PDT) agent that targets CD276, a receptor overexpressed in various tumor cells and tumor vasculature but with limited expression in normal tissue vasculature, could improve the tumor inhibitory efficacy of a PD-1/PD-L1 blockade. A CD276-targeting agent (IRD-αCD276/Fab) was synthesized by conjugating the Fab fragment of an anti-CD276 antibody with a photosensitizer IRDye700. The in vivo tumor-targeting efficacy and therapeutic effects of IRD-αCD276/Fab with or without an anti-PD-1/PD-L1 blockade were tested in subcutaneous and lung metastatic tumor models. PDT using IRD-αCD276/Fab significantly suppressed the growth of subcutaneous 4T1 tumor and inhibited its lung metastasis. Moreover, it triggered in vivo antitumor immunity by increasing the activation and maturation of dendritic cells. Tumor PD-L1 levels were also markedly increased after PDT using IRD-αCD276/Fab, as evidenced by noninvasive PD-L1-targeted small-animal PET imaging. In combination with an anti-PD-1/PD-L1 blockade, IRD-αCD276/Fab PDT markedly suppressed the growth of tumors and prevented their metastasis to the lung by recruiting the tumor infiltration of CD8⁺ T cells. Our data provide evidence for the role of CD276-targeted PDT for local immune modulation, and its combination with PD-L1/PD-1 axis inhibition is a promising strategy for eliminating primary tumors as well as disseminated metastases, by generating local and systemic antitumor responses.

Photoinduced Ligand Release from a Silicon Phthalocyanine Dye Conjugated with Monoclonal Antibodies: A Mechanism of Cancer Cell Cytotoxicity after Near-Infrared Photoimmunotherapy

Photochemical reactions can dramatically alter physical characteristics of reacted molecules. In this study, we demonstrate that near-infrared (NIR) light induces an axial ligand-releasing reaction, which dramatically alters hydrophilicity of a silicon phthalocyanine derivative (IR700) dye leading to a change in the shape of the conjugate and its propensity to aggregate in aqueous solution. This photochemical reaction is proposed as a major mechanism of cell death induced by NIR photoimmunotherapy (NIR-PIT), which was recently developed as a molecularly targeted cancer therapy. Once the antibody-IR700 conjugate is bound to its target, activation by NIR light causes physical changes in the shape of antibody antigen complexes that are thought to induce physical stress within the cellular membrane leading to increases in transmembrane water flow that eventually lead to cell bursting and necrotic cell death.

Near Infrared Photoimmunotherapy with Combined Exposure of External and Interstitial Light Sources

Near infrared photoimmunotherapy (NIR-PIT) is a new target-cell-specific cancer treatment that induces highly selective necrotic/immunogenic cell death after systemic administration of a photoabsorber antibody conjugate and subsequent NIR light exposure. However, the depth of NIR light penetration in tissue (approximately 2 cm) with external light sources limits the therapeutic effects of NIR-PIT. Interstitial light exposure using cylindrical diffusing optical fibers can overcome this limitation. The purpose in this study was to compare three NIR light delivery methods for treating tumors with NIR-PIT using a NIR laser system at an identical light energy; external exposure alone, interstitial exposure alone, and the combination. Panitumumab conjugated with the photoabsorber IRDye-700DX (pan-IR700) was intravenously administered to mice with A431-luc xenografts which are epithelial growth factor receptor (EGFR) positive. One and 2 days later, NIR light was administered to the tumors using one of three methods. Interstitial exposure alone and in combination with external sources showed the greatest decrease in bioluminescence signal intensity. Additionally, the combination of external and interstitial NIR light exposure showed significantly greater tumor size reduction and prolonged survival after NIR-PIT compared to external exposure alone. This result suggested that the combination of external and interstitial NIR light exposure was more effective than externally applied light alone. Although external exposure is the least invasive means of delivering light, the combination of external and interstitial exposures produces superior therapeutic efficacy in tumors greater than 2 cm in depth from the tissue surface.

Radiologist Quality Assurance by Nonradiologists at Tumor Board

PURPOSE

To explore the use of nonradiologists as a method to efficiently reduce bias in the assessment of radiologist performance using a hepatobiliary tumor board as a case study.

MATERIALS AND METHODS

Institutional review board approval was obtained for this HIPAA-compliant prospective quality assurance (QA) effort. Consecutive patients with CT or MR imaging reviewed at one hepatobiliary tumor board between February 2016 and October 2016 (n = 265) were included. All presentations were assigned prospective anonymous QA scores by an experienced nonradiologist hepatobiliary provider based on contemporaneous comparison of the imaging interpretation at a tumor board and the original interpretation(s): concordant, minor discordance, major discordance. Major discordance was defined as a discrepancy that may affect clinical management. Minor discordance was defined as a discrepancy unlikely to affect clinical management. All discordances and predicted management changes were retrospectively confirmed by the liver tumor program medical director. Logistic regression analyses were performed to determine what factors best predict discordant reporting.

RESULTS

Approximately one-third (30% [79 of 265]) of reports were assigned a discordance, including 51 (19%) minor and 28 (11%) major discordances. The most common related to mass size (41% [32 of 79]), tumor stage and extent (24% [19 of 79]), and assigned LI-RADS v2014 score (22% [17 of 79]). One radiologist had 11.8-fold greater odds of discordance (P = .002). Nine other radiologists were similar (P = .10-.99). Radiologists presenting their own studies had 4.5-fold less odds of discordance (P = .006).

CONCLUSIONS

QA conducted in line with tumor board workflow can enable efficient assessment of radiologist performance. Discordant interpretations are commonly (30%) reported by nonradiologist providers.