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

Near-infrared photoimmunotherapy targeting PD-L1: Improved efficacy by preconditioning the tumor microenvironment

Near-infrared photoimmunotherapy (NIR-PIT) is a new type of cancer therapy that employs antibody-IRDye700DX conjugates (AbPCs) and near-infrared (NIR) light at a wavelength of 689 nm, the excitation wavelength of IR700. Administered intravenously, injected AbPCs bind specifically to cells expressing the target antigen, whereupon NIR light exposure causes rapid, selective killing. This process induces an anticancer T cell response, leading to sustained anticancer host immune response. Programmed cell death ligand-1 (PD-L1) is a major inhibitory immune checkpoint molecule expressed in various cancers. In this study, we first assessed the efficacy of PD-L1-targeted NIR-PIT (αPD-L1-PIT) in immune-competent tumor mouse models. αPD-L1-PIT showed a significant therapeutic effect on the tumor models with high PD-L1 expression. Furthermore, αPD-L1-PIT induced an abscopal effect on distant tumors and long-term immunological memory. In contrast, αPD-L1-PIT was not as effective for tumor models with low PD-L1 expression. To improve the efficacy of PD-L1-targeted NIR-PIT, PEGylated interferon-gamma (IFNγ) was administered with αPD-L1-PIT. The combination therapy improved the treatment efficacy by increasing PD-L1 expression leading to more efficient cell killing by αPD-L1-PIT. Furthermore, the PEGylated IFNγ led to a CD8+ T cell-dominant tumor microenvironment (TME) with an enhanced anticancer T cell response after αPD-L1-PIT. As a result, even so-called cold tumors exhibited complete responses after αPD-L1-PIT. Thus, combination therapy of PEGylated IFNγ and PD-L1-targeted NIR-PIT has the potential to be an important future strategy for cancer immunotherapy.

Progress of near-infrared-II fluorescence in precision diagnosis and treatment of colorectal cancer

Colorectal cancer is a malignant tumour with high incidence and mortality worldwide; therefore, improving the early diagnosis of colorectal cancer and implementing a targeted "individualized treatment" strategy is of great concern. NIR-II fluorescence imaging is a large-depth, high-resolution optical bioimaging tool. Around the NIR-II window, researchers have developed a variety of luminescent probes, imaging systems, and treatment methods with colorectal cancer targeting capabilities, which can be visualized and image-guided in clinical surgery. This article aims to overcome the difficulties in diagnosing and treating colorectal cancer. The present review summarizes the latest results on using NIR-II fluorescence for targeted colorectal cancer imaging, expounds on the application prospects of NIR-II optical imaging for colorectal cancer, and discusses the imaging-guided multifunctional diagnosis and treatment platforms.

The chemical basis of cytotoxicity of silicon-phthalocyanine-based near infrared photoimmunotherapy (NIR-PIT) and its implications for treatment monitoring

Near infrared photoimmunotherapy (NIR-PIT) is a new cancer therapy based on the photo-induced ligand release reaction of a silicon-phthalocyanine derivative, IRDye700DX (IR700), that causes rapid cell death. Following exposure to an antibody-IR700-conjugate, cells exposed to NIR light within minutes undergo rapid swelling, blebbing, and finally, bursting. The photo-induced ligand release reaction also induces immediate loss of IR700 fluorescence due to dimerization or aggregation of the antibody-IR700 conjugate allowing for real time monitoring of NIR-PIT therapy.

Near-infrared photoimmunotherapy (NIR-PIT) of bone metastases

The bones are a common site for metastasis arising from solid tumors such as breast and prostate cancer. Chemotherapy, including immunotherapy, is rarely curative. Radiotherapy with pain palliation can temporize bone metastases but is generally considered a short-term solution and retreatment is difficult. Surgery is often necessary, yet recovery times might exceed life expectancy. Therefore, there is a need to develop new approaches to bone metastases that are effective but minimally invasive. Near-infrared photoimmunotherapy (NIR-PIT) uses antibodies labeled with IRDye700DX (IR700) which is activated by NIR light, resulting in rapid cell membrane damage and immunogenic cell death. NIR-PIT using an anti-epidermal growth factor receptor (EGFR) antibody-IR700 conjugate in patients with recurrent head and neck cancer received qualified approval in Japan in 2020 and is now widely used there. However, no bone metastases have yet been treated. In this study, the efficacy of NIR-PIT for bone metastases was investigated using a bone metastases mouse model successfully established by caudal artery injection of a human triple-negative breast cancer cell line, MDAMB468-GFP/luc. The bone metastatic lesions were treated with NIR-PIT using the anti-EGFR antibody, panitumumab-IR700 conjugate. Bioluminescence imaging and histological evaluation showed that EGFR-targeted NIR-PIT has a therapeutic effect on bone metastatic lesions in mice. In addition, micro-CT showed that repeated NIR-PIT led to repair of metastasis-induced bone destruction and restored bone cortex continuity consistent with healing. These data suggest that NIR-PIT has the potential for clinical application in the treatment of bone metastases.

Cutaneous Lymphoma and Antibody-Directed Therapies

The introduction of monoclonal antibodies such as rituximab to the treatment of cancer has greatly advanced the treatment scenario in onco-hematology. However, the response to these agents may be limited by insufficient efficacy or resistance. Antibody–drug conjugates are an attractive strategy to deliver payloads of toxicity or radiation with high selectivity toward malignant targets and limited unwanted effects. Primary cutaneous lymphomas are a heterogeneous group of disorders and a current area of unmet need in dermato-oncology due to the limited options available for advanced cases. This review briefly summarizes our current understanding of T and B cell lymphomagenesis, with a focus on recognized molecular alterations that may provide investigative therapeutic targets. The authors reviewed antibody-directed therapies investigated in the setting of lymphoma: this term includes a broad spectrum of approaches, from antibody–drug conjugates such as brentuximab vedotin, to bi-specific antibodies, antibody combinations, antibody-conjugated nanotherapeutics, radioimmunotherapy and, finally, photoimmunotherapy with specific antibody–photoadsorber conjugates, as an attractive strategy in development for the future management of cutaneous lymphoma.

Click Chemistry-Generated Auristatin F-Linker-Benzylguanine for a SNAP-Tag-Based Recombinant Antibody-Drug Conjugate Demonstrating Selective Cytotoxicity toward EGFR-Overexpressing Tumor Cells

Antibody-drug conjugates (ADCs) are bifunctional molecules combining the targeting potential of monoclonal antibodies with the cancer-killing ability of cytotoxic drugs. This simple yet intelligently designed system directly addresses the lack of specificity encountered with conventional anti-cancer treatment regimes. However, despite their initial success, the generation of clinically sustainable and effective ADCs has been plagued by poor tumor penetration, undefined chemical linkages, unpredictable pharmacokinetic profiles, and heterogeneous mixtures of products. To this end, we generated a SNAP-tag-based fusion protein targeting the epidermal growth factor receptor (EGFR)-a biomarker of aggressive and drug-resistant cancers. Here, we demonstrate the use of a novel click coupling strategy to engineer a benzylguanine (BG)-linker-auristatin F (AuriF) piece that can be covalently tethered to the EGFR-targeting SNAP-tag-based fusion protein in an irreversible 1:1 stoichiometric reaction to form a homogeneous product. Furthermore, using these recombinant ADCs to target EGFR-overexpressing tumor cells, we provide a proof-of-principle for generating biologically active antimitotic therapeutic proteins capable of inducing cell death in a dose-dependent manner, thus alleviating some of the challenges of early ADC development.

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.

A magnetic antibody-conjugated nano-system for selective delivery of Ca(OH)2 and taxotere in ovarian cancer cells

An efficient strategy for cancer therapy is presented, in which a tumor mass is initially pretreated with calcium hydroxide, then treated with Taxotere (TXT). In this regard, an advanced delivery system based on iron oxide nanoparticles has been designed. The surface of nanoparticles was functionalized with sortilin (SORT-1, a human IgG1 monoclonal antibody) that specifically encodes caov-4 ovarian cancerous cells. Plasmonic heating of the incorporated gold nanoparticles in polyvinyl alcohol (PVA) has been exploited to control the release process of TXT. The in vitro, ex vivo and in vivo experiments have exhibited high efficacy of a seven-day pretreatment by Ca(OH)₂ plus 14 days treatment program by Ca(OH)₂@Fe₃O₄/PVA/Au-SORT nano-therapeutics, where more penetration ratio resulted in tumor growth inhibition by ca. 78.3%. As a result, due to showing high values of the anti-tumor properties and biosafety, the presented pretreatment strategy is suggested for more effective treatment on the aged tumors.

A magnetic drug delivery system containing polyvinyl alcohol, gold nanoparticles, and sortilin antibody followed by the plasmonic photothermal heating strategy for the controlled drug release is proposed, with use in ovarian cancer demonstrated.

New Technologies Bloom Together for Bettering Cancer Drug Conjugates

Drug conjugates, including antibody-drug conjugates, are a step toward realizing Paul Ehrlich's idea from over 100 years ago of a "magic bullet" for cancer treatment. Through balancing selective targeting molecules with highly potent payloads, drug conjugates can target specific tumor microenvironments and kill tumor cells. A drug conjugate consists of three parts: a targeting agent, a linker, and a payload. In some conjugates, monoclonal antibodies act as the targeting agent, but new strategies for targeting include antibody derivatives, peptides, and even small molecules. Linkers are responsible for connecting the payload to the targeting agent. Payloads impact vital cellular processes to kill tumor cells. At present, there are 12 antibody-drug conjugates on the market for different types of cancers. Research on drug conjugates is increasing year by year to solve problems encountered in conjugate design, such as tumor heterogeneity, poor circulation, low drug loading, low tumor uptake, and heterogenous expression of target antigens. This review highlights some important preclinical research on drug conjugates in recent years. We focus on three significant areas: improvement of antibody-drug conjugates, identification of new conjugate targets, and development of new types of drug conjugates, including nanotechnology. We close by highlighting the critical barriers to clinical translation and the open questions going forward. SIGNIFICANCE STATEMENT: The development of anticancer drug conjugates is now focused in three broad areas: improvements to existing antibody drug conjugates, identification of new targets, and development of new conjugate forms. This article focuses on the exciting preclinical studies in these three areas and advances in the technology that improves preclinical development.

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.

Therapeutic Options for Recurrent Glioblastoma—Efficacy of Talaporfin Sodium Mediated Photodynamic Therapy

Recurrent glioblastoma (GBM) remains one of the most challenging clinical issues, with no standard treatment and effective treatment options. To evaluate the efficacy of talaporfin sodium (TS) mediated photodynamic therapy (PDT) as a new treatment for this condition, we retrospectively analyzed 70 patients who underwent surgery with PDT (PDT group) for recurrent GBM and 38 patients who underwent surgery alone (control group). The median progression-free survival (PFS) in the PDT and control groups after second surgery was 5.7 and 2.2 months, respectively (p = 0.0043). The median overall survival (OS) after the second surgery was 16.0 and 12.8 months, respectively (p = 0.031). Both univariate and multivariate analyses indicated that surgery with PDT and a preoperative Karnofsky Performance Scale were significant independent prognostic factors for PFS and OS. In the PDT group, there was no significant difference regarding PFS and OS between patients whose previous pathology before recurrence was already GBM and those who had malignant transformation to GBM from lower grade glioma. There was also no significant difference in TS accumulation in the tumor between these two groups. According to these results, additional PDT treatment for recurrent GBM could have potential survival benefits and its efficacy is independent of the pre-recurrence pathology.

Selection of antibody and light exposure regimens alters therapeutic effects of EGFR-targeted near-infrared photoimmunotherapy

Near-infrared photoimmunotherapy (NIR-PIT) is a cell-specific cancer therapy that uses an antibody-photoabsorber (IRDye700DX, IR700) conjugate (APC) and NIR light. Intravenously injected APC binds the target cells, and subsequent NIR light exposure induces immunogenic cell death only in targeted cells. Panitumumab and cetuximab are antibodies that target human epidermal growth factor receptor (hEGFR) and are suitable for NIR-PIT. In athymic nude mouse models, panitumumab-based NIR-PIT showed superior therapeutic efficacy compared to cetuximab-based NIR-PIT because of the longer half-life of panitumumab-IR700 (pan-IR700) compared with cetuximab-IR700 (cet-IR700). Two light exposures on two consecutive days have also been shown to induce superior effects compared to a single light exposure in the athymic nude mouse model. However, the optimal regimen has not been assessed in immunocompetent mice. In this study, we compared panitumumab and cetuximab in APCs for NIR-PIT, and single and double light exposures using a newly established hEGFR-expressing cancer cell line derived from immunocompetent C57BL/6 mice (mEERL-hEGFR cell line). Fluorescence imaging showed that the decline of pan-IR700 was slower than cet-IR700 confirming a longer clearance time. Among all the combinations tested, mice receiving pan-IR700 and double light exposure showed the greatest tumor growth inhibition. This group was also shown to activate CD8⁺ T lymphocytes in lymph nodes and accumulate CD8⁺ T lymphocytes to a greater extent within the tumor compared with the control group. These results showed that APCs with longer half-life and double light exposure lead to superior outcomes in cancer cell-targeted NIR-PIT in an immunocompetent mouse model.

Quantitative Assessment of the Efficacy of Near-Infrared Photoimmunotherapy with Bioluminescence Imaging

Near-infrared photoimmunotherapy (NIR-PIT) is a cell-specific cancer therapy in which antibody-photoabsorber conjugates (APCs) are activated by NIR light to induce rapid immunogenic cell death with minimal off-target effects. In preclinical settings, bioluminescence imaging (BLI) is useful to quantitatively assess the efficacy of NIR-PIT for both in vitro and in vivo experiments, especially in the early phase of testing. Here, we describe the detailed methods of the experiments for NIR-PIT and evaluation of its efficacy using BLI.

Precise Diagnosis and Therapy of Bone Cancer Using Near-Infrared Lights

Bone is a preferred site for both primary and metastasis tumors. Current diagnosis of osteopathia typically relies on noninvasive skeleton radiography technology. However, due to the limited resolution of ionizing radiation, accurate diagnosis and effective identification impairment areas are still lacking. Near-infrared (NIR) bioimaging, especially in the NIR-II (1000-1700 nm) regions, can provide high sensitivity and spatiotemporal resolution bioimaging compared to the conventional radiography. Thus, NIR bioimaging affords intraoperative visualization and imaging-guided surgery, aiming to overcome challenges associated with theranostics of osteopathia and bone tumors. The present review aimed to summarize the latest evidence on the use of NIR probes for the targeting bone imaging. We further highlight the recent advances in bone photoX (X presents thermal, dynamic, and immuno) therapy through NIR probes, in particular combination with other customized therapeutic agents could provide high-efficiency treatment for bone tumors.

Electron Donors Rather Than Reactive Oxygen Species Needed for Therapeutic Photochemical Reaction of Near-Infrared Photoimmunotherapy

Near-infrared photoimmunotherapy (NIR-PIT) employs molecularly targeted antibodies conjugated with a photoabsorbing silicon-phthalocyanine dye derivative which binds to cancer cells. Application of NIR light following binding of the antibody-photoabsorber conjugates (APCs) results in ligand release on the dye, dramatic changes in solubility of the APC-antigen complex, and rapid, irreversible cell membrane damage of cancer cells in a highly selective manner, resulting in a highly immunogenic cell death. Clinically, this process results in edema after treatment mediated by reactive oxygen species (ROS). Based on the chemical and biological mechanism of NIR-PIT cytotoxicity and edema formation, in order to minimize acute inflammatory edema without compromising therapeutic effects, l-sodium ascorbate (l-NaAA) was administered to quench harmful ROS and accelerate the ligand release reaction. l-NaAA suppressed acute edema by reducing ROS after NIR-PIT yet did not alter the therapeutic effects. NIR-PIT could be performed safely under existence of l-NaAA without side effects caused by unnecessary ROS production.

Antibody-Based Targeted Interventions for the Diagnosis and Treatment of Skin Cancers

BACKGROUND

Cutaneous malignancies most commonly arise from skin epidermal cells. These cancers may rapidly progress from benign to a metastatic phase. Surgical resection represents the gold standard therapeutic treatment of non-metastatic skin cancer while chemo- and/or radiotherapy are often used against metastatic tumors. However, these therapeutic treatments are limited by the development of resistance and toxic side effects, resulting from the passive accumulation of cytotoxic drugs within healthy cells.

OBJECTIVE

This review aims to elucidate how the use of monoclonal Antibodies (mAbs) targeting specific Tumor Associated Antigens (TAAs) is paving the way to improved treatment. These mAbs are used as therapeutic or diagnostic carriers that can specifically deliver cytotoxic molecules, fluorophores or radiolabels to cancer cells that overexpress specific target antigens.

RESULTS

mAbs raised against TAAs are widely in use for e.g. differential diagnosis, prognosis and therapy of skin cancers. Antibody-Drug Conjugates (ADCs) particularly show remarkable potential. The safest ADCs reported to date use non-toxic photo-activatable Photosensitizers (PSs), allowing targeted Photodynamic Therapy (PDT) resulting in targeted delivery of PS into cancer cells and selective killing after light activation without harming the normal cell population. The use of near-infrared-emitting PSs enables both diagnostic and therapeutic applications upon light activation at the specific wavelengths.

CONCLUSION

Antibody-based approaches are presenting an array of opportunities to complement and improve current methods employed for skin cancer diagnosis and treatment.

Photodynamic Therapy: Targeting Cancer Biomarkers for the Treatment of Cancers

Simple Summary

Photodynamic therapy (PDT) is a minimally invasive treatment option that can kill cancerous cells by subjecting them to light irradiation at a specific wavelength. The main problem related to most photosensitizers is the lack of tumor selectivity, which leads to undesired uptake in normal tissues resulting in side effects. Passive targeting and active targeting are the two strategies to improve uptake in tumor tissues. This review focused on active targeting and summarizes recent active targeting approaches in which highly potent photosensitizers are rendered tumor-specific by means of an appended targeting moiety that interacts with a protein unique to, or at least significantly more abundant on, tumor cell surfaces compared to normal cells.

Abstract

Photodynamic therapy (PDT) is a well-documented therapy that has emerged as an effective treatment modality of cancers. PDT utilizes harmless light to activate non- or minimally toxic photosensitizers to generate cytotoxic species for malignant cell eradication. Compared with conventional chemotherapy and radiotherapy, PDT is appealing by virtue of the minimal invasiveness, its safety, as well as its selectivity, and the fact that it can induce an immune response. Although local illumination of the cancer lesions renders intrinsic selectivity of PDT, most photosensitizers used in PDT do not display significant tumor tissue selectivity. There is a need for targeted delivery of photosensitizers. The molecular identification of cancer antigens has opened new possibilities for the development of effective targeted therapy for cancer patients. This review provides a brief overview of recent achievements of targeted delivery of photosensitizers to cancer cells by targeting well-established cancer biomarkers. Overall, targeted PDT offers enhanced intracellular accumulation of the photosensitizer, leading to improved PDT efficacy and reduced toxicity to normal tissues.

Chromatographic analysis of site-specific antibody-drug conjugates produced by AJICAP first-generation technology using a recombinant FcγIIIa receptor-ligand affinity column

Commercially approved conventional antibody-drug conjugates (ADCs) are produced as heterogeneous mixtures containing a stochastic distribution of payloads decorating the antibody molecules resulting in decreased efficacy and thus lowering their therapeutic index. Control of the DAR and conjugation site in the development of next-generation ADCs is believed to assist in increasing the therapeutic index of these targeted biologics leading to overall enhanced clinical efficacy and reduced toxicity. A chemical site-specific conjugation technology termed AJICAP® allows ADC developers to control both the location and quantity of the payload conjugation to an antibody. Furthermore, this simplified ADC composition enables a streamlined chemical analysis. Here we report the chromatographic separation of site-specific ADCs produced by AJICAP® technology using an analytical affinity chromatography HPLC column containing a recombinant FcγIIIa receptor-ligand immobilized on a non-porous polymer resin (NPR). These HPLC analyses provided visually clear chromatogram results reflecting the heterogeneity of each ADC. The affinity strength was also measured by biolayer interferometry (BLI) and predicted by molecular structure analysis. The results indicate that AJICAP® technology is a promising solution to link hydrophobic payloads to antibodies without compromising antibody receptor function. This study also shows that FcγIIIa-NPR column can be used to characterize site-specific conjugated ADCs compared to ADCs synthesized using conventional methods.

Real-time IR700 Fluorescence Imaging During Near-infrared Photoimmunotherapy Using a Clinically-approved Camera for Indocyanine Green

BACKGROUND/AIM

Near-infrared photoimmuno-therapy (NIR-PIT) is a newly approved cancer phototherapy. We aim to confirm whether a clinically approved camera for indocyanine green (ICG) could monitor IR700 fluorescence in real time during exposure to therapeutic NIR light.

MATERIALS AND METHODS

An NIR camera, LIGHTVISION, designed to image ICG fluorescence, was used. A431-GFP/luc tumor-bearing mice were exposed to therapeutic NIR light and real-time fluorescence imaging (RT-FI) was obtained and measured with LIGHTVISION. Bioluminescence imaging (BLI) was performed to confirm cell death.

RESULTS

RT-FI during NIR-PIT revealed an initial rapid loss of fluorescence, followed by a plateau which occurred at a light dose of approximately 30 J/cm ² . Correlation between BLI and IR700 fluorescence loss showed that loss of fluorescence was associated with increased cell death.

CONCLUSION

The efficacy of NIR-PIT could be monitored non-invasively and in real-time using weak fluorescence at wavelengths much longer than the peak fluorescence of IR700. This technique can achieve precise light dosimetry that allows us to decide on the optimal exposure.

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.

Prostate-specific membrane antigen (PSMA)-targeted photodynamic therapy enhances the delivery of PSMA-targeted magnetic nanoparticles to PSMA-expressing prostate tumors

Enhanced vascular permeability in tumors plays an essential role in nanoparticle delivery. Prostate-specific membrane antigen (PSMA) is overexpressed on the epithelium of aggressive prostate cancers (PCs). Here, we evaluated the feasibility of increasing the delivery of PSMA-targeted magnetic nanoparticles (MNPs) to tumors by enhancing vascular permeability in PSMA(+) PC tumors with PSMA-targeted photodynamic therapy (PDT).

Method: PSMA(+) PC3 PIP tumor-bearing mice were given a low-molecular-weight PSMA-targeted photosensitizer and treated with fluorescence image-guided PDT, 4 h after. The mice were then given a PSMA-targeted MNP immediately after PDT and monitored with fluorescence imaging and T₂-weighted magnetic resonance imaging (T₂-W MRI) 18 h, 42 h, and 66 h after MNP administration. Untreated PSMA(+) PC3 PIP tumor-bearing mice were used as negative controls.

Results: An 8-fold increase in the delivery of the PSMA-targeted MNPs was detected using T₂-W MRI in the pretreated tumors 42 h after PDT, compared to untreated tumors. Additionally, T₂-W MRIs revealed enhanced peripheral intra-tumoral delivery of the PSMA-targeted MNPs. That finding is in keeping with two-photon microscopy, which revealed higher vascular densities at the tumor periphery.

Conclusion: These results suggest that PSMA-targeted PDT enhances the delivery of PSMA-targeted MNPs to PSMA(+) tumors by enhancing the vascular permeability of the tumors.

Fluorescence Imaging of Tumor-Accumulating Antibody-IR700 Conjugates Prior to Near-Infrared Photoimmunotherapy (NIR-PIT) Using a Commercially Available Camera Designed for Indocyanine Green

Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed cancer treatment that uses antibody-IRDye700DX (IR700) conjugates and was recently approved in Japan for patients with inoperable head and neck cancer. Exposure of the tumor with NIR light at a wavelength of 690 nm leads to physicochemical changes in the antibody-IR700 conjugate-cell receptor complex, resulting in increased hydrophobicity and damage to the integrity of the cell membrane. However, it is important that the tumor be completely exposed to light during NIR-PIT, and thus, a method to provide real-time information on tumor location would help clinicians direct light more accurately. IR700 is a fluorophore that emits at 702 nm; however, there is no clinically available device optimized for detecting this fluorescence. On the other hand, many indocyanine green (ICG) fluorescence imaging devices have been approved for clinical use in operating rooms. Therefore, we investigated whether LIGHTVISION, one of the clinically available ICG cameras, could be employed for NIR-PIT target tumor detection. Due to the limited benefits of adding IR700 molecules, the additional conjugation of IRDye800CW (IR800) or ICG-EG4-Sulfo-OSu (ICG-EG4), which has an overlapping spectrum with ICG, to trastuzumab-IR700 conjugates was performed. Conjugation of second NIR dyes did not interfere the efficacy of NIR-PIT. The dual conjugation of IR800 and IR700 to trastuzumab clearly visualized target tumors with LIGHTVISION by detecting emission light of IR800. We demonstrated that the conjugation of second NIR dyes enables us to provide a real-time feedback of tumor locations prior to NIR-PIT.

Near-infrared photoimmunotherapy (NIR-PIT) on cholangiocarcinoma using a novel catheter device with light emitting diodes

Near-infrared photoimmunotherapy (NIR-PIT) is a novel therapy for cancers that uses NIR light and antibody-photosensitizer (IR700) conjugates. However, it is difficult to deliver NIR light into the bile duct for cholangiocarcinoma (CCA) from the conventional extracorporeal apparatus. Thus, in this study, we developed a dedicated catheter with light emitting diodes (LEDs) that supersedes conventional external irradiation devices; we investigated the therapeutic effect of NIR-PIT for CCA using the novel catheter. The new catheter was designed to be placed in the bile duct and a temperature sensor was attached to the tip of the catheter to avoid thermal burn. An anti-epidermal growth factor receptor (EGFR) antibody, Panitumumab-IR700 conjugate or anti-human epidermal growth factor receptor type 2 (HER2) antibody, Trastuzumab-IR700 conjugate, was used with EGFR- or HER2-expressing cell lines, respectively. The in vitro efficacy of NIR-PIT was confirmed in cultured cells; the capability of the new catheter for NIR-PIT was then tested in a mouse tumor model. NIR-PIT via the developed catheter treated CCA xenografts in mice. NIR-PIT had an effect in Panitumumab-IR700 conjugate- and Trastuzumab-IR700 conjugate-treated CCA cells that depended on the receptor expression level. Tumor growth was significantly suppressed in mice treated with NIR-PIT using the novel catheter compared with controls (P < .01). NIR-PIT was an effective treatment for EGFR- and HER2-expressing CCA cells, and the novel catheter with mounted LEDs was useful for NIR-PIT of CCA.

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.

Near infrared photoimmunotherapy targeting the cutaneous lymphocyte antigen for mycosis fungoides

Background: Mycosis fungoides (MF) is a low-grade T-cell lymphoma with primary cutaneous involvement accounting for more than half of all primary cutaneous lymphomas. The treatment of MF is very challenging due to the limited therapies available. Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed and highly selective cancer treatment that employs a monoclonal antibody conjugated to a photo-absorber dye, the hydrophilic phthalocyanine IRdye 700DX® (IR700), and near infrared light. In this study, we investigated the effect of NIR-PIT on MF targeting the cell-surface antigen cutaneous lymphocyte antigen (CLA)Matherial and methods: MF derived My-La CD4+ cells were incubated with the anti-CLA antibody conjugated to IR700 and then irradiated with a 690 nm near-infrared light. Cell death was evaluated by propidium iodide staining and flow cytometry 24 hours after irradiation.Results: Treatment with anti-CLA or light irradiation exhibited very modest pro-death effects, whereas treatment with the anti-CLA antibody conjugated to IR700 and then irradiation with a 690 nm near-infrared light induced a substantial increase in death in the MF cell line.Conclusions: NIR-PIT targeting CLA to treat MF showed marked antitumour effects. As such, CLA-targeted NIR-PIT could be a promising treatment for MF and, possibly, other cutaneous diseases characterized by CLA+ skin infiltrating T-cells.

Advances in epidermal growth factor receptor specific immunotherapy: lessons to be learned from armed antibodies

The epidermal growth factor receptor (EGFR) has been recognized as an important therapeutic target in oncology. It is commonly overexpressed in a variety of solid tumors and is critically involved in cell survival, proliferation, metastasis, and angiogenesis. This multi-dimensional role of EGFR in the progression and aggressiveness of cancer, has evolved from conventional to more targeted therapeutic approaches. With the advent of hybridoma technology and phage display techniques, the first anti-EGFR monoclonal antibodies (mAbs) (Cetuximab and Panitumumab) were developed. Due to major limitations including host immune reactions and poor tumor penetration, these antibodies were modified and used as guiding mechanisms for the specific delivery of readily available chemotherapeutic agents or plants/bacterial toxins, giving rise to antibody-drug conjugates (ADCs) and immunotoxins (ITs), respectively. Continued refinement of ITs led to deimmunization strategies based on depletion of B and T-cell epitopes or substitution of non-human toxins leading to a growing repertoire of human enzymes capable of inducing cell death. Similarly, the modification of classical ADCs has resulted in the first, fully recombinant versions. In this review, we discuss significant advancements in EGFR-targeting immunoconjugates, including ITs and recombinant photoactivable ADCs, which serve as a blueprint for further developments in the evolving domain of cancer immunotherapy.

Near-Infrared Photoimmunotherapy Combined with CTLA4 Checkpoint Blockade in Syngeneic Mouse Cancer Models

Near infrared photoimmunotherapy (NIR-PIT) is a newly developed and highly selective cancer treatment that induces necrotic/immunogenic cell death. It employs a monoclonal antibody (mAb) conjugated to a photo-absorber dye, IRDye700DX, which is activated by NIR light. Tumor-targeting NIR-PIT is also at least partly mediated by a profound immune response against the tumor. Cytotoxic T-lymphocyte antigen-4 (CTLA4) is widely recognized as a major immune checkpoint protein, which inhibits the immune response against tumors and is therefore, a target for systemic blockade. We investigated the effect of combining tumor-targeted NIR-PIT against the cell-surface antigen, CD44, which is known as a cancer stem cell marker, with a systemic CTLA4 immune checkpoint inhibitor in three syngeneic tumor models (MC38-luc, LL/2, and MOC1). CD44-targeted NIR-PIT combined with CTLA4 blockade showed greater tumor growth inhibition with longer survival compared with CTLA4 blockade alone in all tumor models. NIR-PIT and CTLA4 blockade produced more complete remission in MOC1 tumors (44%) than NIR-PIT and programmed cell death protein 1 (PD-1) blockade (8%), which was reported in our previous paper. However, the combination of NIR-PIT and CTLA4 blockade was less effective in MC38-luc tumors (11%) than the combination of NIR-PIT and PD-1 blockade (70%). Nonetheless, in many cases ineffective results with NIR-PIT and PD-1 blockade were reversed with NIR-PIT and CTLA4 blockade.

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.

Antibody-Based Immunotherapy: Alternative Approaches for the Treatment of Metastatic Melanoma

Melanoma is the least common form of skin cancer and is associated with the highest mortality. Where melanoma is mostly unresponsive to conventional therapies (e.g., chemotherapy), BRAF inhibitor treatment has shown improved therapeutic outcomes. Photodynamic therapy (PDT) relies on a light-activated compound to produce death-inducing amounts of reactive oxygen species (ROS). Their capacity to selectively accumulate in tumor cells has been confirmed in melanoma treatment with some encouraging results. However, this treatment approach has not reached clinical fruition for melanoma due to major limitations associated with the development of resistance and subsequent side effects. These adverse effects might be bypassed by immunotherapy in the form of antibody–drug conjugates (ADCs) relying on the ability of monoclonal antibodies (mAbs) to target specific tumor-associated antigens (TAAs) and to be used as carriers to specifically deliver cytotoxic warheads into corresponding tumor cells. Of late, the continued refinement of ADC therapeutic efficacy has given rise to photoimmunotherapy (PIT) (a light-sensitive compound conjugated to mAbs), which by virtue of requiring light activation only exerts its toxic effect on light-irradiated cells. As such, this review aims to highlight the potential clinical benefits of various armed antibody-based immunotherapies, including PDT, as alternative approaches for the treatment of metastatic melanoma.

Conjugation Ratio, Light Dose, and pH Affect the Stability of Panitumumab-IR700 for Near-Infrared Photoimmunotherapy

Near-infrared photoimmunotherapy (NIR-PIT), a newly developed cancer-cell-specific therapy, relies on a monoclonal antibody-photoabsorber conjugate (APC) and is based on a photoinduced ligand release reaction. Local exposure of the tumor to NIR light induces rapid immunogenic necrotic cell death. The molecular properties of APCs, including their stability and aggregation properties, have important implications for the long-term stability and shelf life. In this study, panitumumab was conjugated with IRDye700DX (IR700) as a model for other NIR-PIT agents. Higher IR700-to-mAb conjugation ratios correlated with increased in vitro cell death up to a ratio of 2.5 dye molecules per antibody. Conjugation ratios higher than 2.5 did not improve cell killing activity. APC aggregation was induced in a light-dose-dependent manner. A near-room-level light dose was sufficient to induce aggregation of APCs. Solvent pH lower than 4 induced aggregation, but higher pH did not induce aggregation. The IR700-to-mAb conjugation ratio, light irradiation dose, and solvent pH affect the APC stability and efficacy.

Near-infrared photoimmunotherapy is effective treatment for colorectal cancer in orthotopic nude-mouse models

BACKGROUND

Photoimmunotherapy (PIT) employs the use of a near-infrared (NIR) laser to activate an antibody conjugated to a NIR-activatable dye to induce cancer cell death. PIT has shown to be effective in a number of studies, however, there are no data on its use in colorectal cancer in an orthotopic model.

METHODS

Humanized anti-CEA antibody (M5A) was conjugated to NIR-activatable IRDye700DX (M5A-700). PIT was validated in vitro with a colon cancer cell-line, using a laser intensity of either 4 J/cm2, 8 J/cm2, or 16 J/cm2. Orthotopic colon cancer mouse models were established by surgical implantation of LS174T tumor fragments onto the cecum. M5A-700 was administered and PIT was performed 24 hours later using a 690 nm laser. Repeat PIT was performed after 7 days in one group. Control mice received laser treatment only.

RESULTS

In vitro PIT demonstrated tumor cell death in a laser intensity dose-dependent fashion. In orthotopic models, control mice demonstrated persistent tumor growth. Mice that underwent PIT one time had tumor growth arrested for one week, after which re-growth occurred. The group that received repeated PIT exposure had persistent inhibition of tumor growth.

CONCLUSION

PIT arrests tumor growth in colon cancer orthotopic nude-mouse models. Repeated PIT arrests colon cancer growth for a longer period of time. PIT may be a useful therapy in the future as an adjunct to surgical resection or as primary therapy to suppress tumor progression.

A near-infrared light-mediated cleavable linker strategy using the heptamethine cyanine chromophore

Optical methods offer the potential to manipulate living biological systems with exceptional spatial and temporal control. Caging bioactive molecules with photocleavable functional groups is an important strategy that could be applied to a range of problems, including the targeted delivery of otherwise toxic therapeutics. However existing approaches that require UV or blue light are difficult to apply in organismal settings due to issues of tissue penetration and light toxicity. Photocaging groups built on the heptamethine cyanine scaffold enable the targeted delivery of bioactive molecules using near-IR light (up to 780nm) in live animal settings. Here we provide a detailed procedure demonstrating the utility of the heptamethine cyanine caging group to create a light-cleavable linker between an antibody, panitumumab, and a therapeutic small molecule in the duocarmycin class of natural products. Descriptions of the design and synthesis of the small molecule component, assembly of the antibody conjugate, in vitro analysis of uncaging, in vivo imaging, and impact on tumor progression are provided.

Selective Photokilling of Colorectal Tumors by Near-Infrared Photoimmunotherapy with a GPA33-Targeted Single-Chain Antibody Variable Fragment Conjugate

Antibody-based near-infrared photoimmunotherapy (NIR-PIT) is an attractive strategy for cancer treatment. Tumor cells can be selectively and efficiently killed by the targeted delivery of an antibody-photoabsorber complex followed by exposure to NIR light. Glycoprotein A33 antigen (GPA33) is highly expressed in most human colorectal cancers (CRCs) and is an ideal diagnostic and therapeutic target. We previously produced a single-chain fragment of a variable antibody against GPA33 (A33scFv antibody). Here, we investigate the efficacy of NIR-PIT by combining A33scFv with the NIR photoabsorber IR700 (A33scFv-IR700). In vitro, recombinant A33scFv displayed specific binding and delivery of an NIR dye to GPA33-positive tumor cells. Furthermore, A33scFv-IR700-mediated NIR-PIT was successful in rapidly and specifically killing GPA33-positive colorectal tumor cells. NIR-PIT treatment induced the release of lactate dehydrogenase from tumor cells, followed by cell necrosis, rather than apoptosis, through the promotion of reactive oxygen species accumulation in tumor cells. In mice bearing LS174T tumor grafts, A33scFv selectively accumulated in GPA33-positive tumors. Following only a single injection of the conjugate and subsequent illumination, A33scFv-IR700-mediated NIR-PIT induced a significant increase in therapeutic response in LS174T-tumor mice compared with that in the non-NIR-PIT groups (p < 0.001). Because the GPA33 antigen is specifically expressed in CRC tumors, A33scFv-IR700 might be a promising antibody fragment-photoabsorber conjugate for NIR-PIT of CRC.

Highly versatile cancer photoimmunotherapy using photosensitizer-conjugated avidin and biotin-conjugated targeting antibodies

Background

Photoimmunotherapy (PIT) employing antibody-photosensitizer conjugates is a promising treatment for cancer. However, the fixed antigen specificity severely limits the efficacy and the applicability. Here we describe a universal strategy for PIT of cancer by using a near-infrared (NIR) photosensitizer IRDye700DX-conjugated NeutrAvidin, designated as AvIR, together with various biotinylated antibodies (BioAbs) for cellular targeting.

Methods

Cytotoxicity of AvIR-mediated PIT was evaluated by fluorescence imaging and cell viability assay. Phototoxic effect on tumorigenicity was assessed by tumorsphere-formation assay and Matrigel invasion assay. Cancer stem cell-like side-population (SP) cells were identified by flow cytometry.

Results

CHO cells stably expressing carcinoembryonic antigen or EpCAM were pre-labeled with each BioAb for the corresponding antigen, followed by AvIR administration. NIR light irradiation specifically killed the targeted cells, but not off-targets, demonstrating that the AvIR-mediated PIT does work as expected. CSC-like subpopulation of MCF-7 cells (CD24^low/CD44^high) and SP of HuH-7 cells (CD133⁺/EpCAM⁺) were effectively targeted and photokilled by AvIR-PIT with anti-CD44 BioAb or anti-CD133/anti-EpCAM BioAbs, respectively. As results, the neoplastic features of the cell lines were sufficiently suppressed. Cancer-associated fibroblast (CAF)-targeted AvIR-PIT by using anti-fibroblast activation protein BioAb showed an abolishment of CAF-enhanced clonogenicity of MCF-7 cells.

Conclusions

Collectively, our results demonstrate that AvIR-mediated PIT can greatly broaden the applicable range of target specificity, with feasibility of efficacious and integrative control of CSC and its microenvironment.