Syngeneic Mouse Models of Oral Cancer Are Effectively Targeted by Anti-CD44-Based NIR-PIT

Enhancing the efficacy of near-infrared photoimmunotherapy through intratumoural delivery of CD44-targeting antibody-photoabsorber conjugates

BACKGROUND

Photoimmunotherapy (PIT) is a potent modality for cancer treatment. The conventional PIT regimen involves the systemic delivery of an antibody-photoabsorber conjugate, followed by a 24-h waiting period to ensure adequate localisation on the target cells. Subsequent exposure to near-infrared (NIR) light selectively damages the target cells. We aimed to improve the efficacy of PIT in vivo by evaluating the effects of the different routes of conjugate administration on treatment outcomes.

METHODS

Subcutaneous Lewis lung carcinoma tumours were established in mice, targeting cluster of differentiation (CD)44 with an anti-CD44 antibody conjugated to IRDye700DX (IR700). The conjugate was administered via the intravenous or intratumoural route followed by the assessment of antibody binding and therapeutic effects of PIT.

FINDINGS

Compared to intravenous administration, intratumoural delivery of the CD44-IR700 conjugate significantly increased the number of cells binding to the conjugate by >five-fold. This method, combined with NIR light irradiation, halved tumour growth when compared to intravenous delivery. Reducing the interval between intratumoural injection and NIR light exposure to 30 min did not diminish efficacy, thereby demonstrating the feasibility of a 1-h procedure.

INTERPRETATION

Intratumoural administration of the antibody-photoabsorber conjugate enhanced the efficacy of PIT in vivo. A simplified, 1-h procedure involving conjugate tumour injection followed by irradiation emerged as a potent cancer treatment strategy.

FUNDING

This study was supported by the Japan Society for the Promotion of Science, the Japan Agency for Medical Research and Development, Japan Science and Technology Agency, and the Osaka Medical Research Foundation for Intractable Diseases.

Anti-CD44 Variant 10 Monoclonal Antibody Exerts Antitumor Activity in Mouse Xenograft Models of Oral Squamous Cell Carcinomas

CD44 regulates cell adhesion, proliferation, survival, and stemness and has been considered a tumor therapy target. CD44 possesses the shortest CD44 standard (CD44s) and a variety of CD44 variant (CD44v) isoforms. Since the expression of CD44v is restricted in epithelial cells and carcinomas compared to CD44s, CD44v has been considered a promising target for monoclonal antibody (mAb) therapy. We previously developed an anti-CD44v10 mAb, C44Mab-18 (IgM, kappa), to recognize the variant exon 10-encoded region. In the present study, a mouse IgG2a version of C44Mab-18 (C44Mab-18-mG2a) was generated to evaluate the antitumor activities against CD44-positive cells compared with the previously established anti-pan CD44 mAb, C44Mab-46-mG2a. C44Mab-18-mG2a exhibited higher reactivity compared with C44Mab-46-mG2a to CD44v3-10-overexpressed CHO-K1 (CHO/CD44v3-10) and oral squamous cell carcinoma cell lines (HSC-2 and SAS) in flow cytometry. C44Mab-18-mG2a exerted a superior antibody-dependent cellular cytotoxicity (ADCC) against CHO/CD44v3-10. In contrast, C44Mab-46-mG2a showed a superior complement-dependent cytotoxicity (CDC) against CHO/CD44v3-10. A similar tendency was observed in ADCC and CDC against HSC-2 and SAS. Furthermore, administering C44Mab-18-mG2a or C44Mab-46-mG2a significantly suppressed CHO/CD44v3-10, HSC-2, and SAS xenograft tumor growth compared with the control mouse IgG2a. These results indicate that C44Mab-18-mG2a could be a promising therapeutic regimen for CD44v10-positive tumors.

An Investigation into the In Vitro Targeted Killing of CD44-Expressing Triple-Negative Breast Cancer Cells Using Recombinant Photoimmunotherapeutics Compared to Auristatin-F-Based Antibody-Drug Conjugates

Triple-negative breast cancer (TNBC) is the deadliest form of breast cancer with limited treatment options. The persistence of highly tumorigenic CD44-expressing subpopulation referred to as cancer stem cells (CSCs), endowed with the self-renewal capacity, has been associated with therapeutic resistance, hence clinical relapses. To mitigate these undesired events, targeted immunotherapies using antibody-photoconjugate (APC) or antibody-drug conjugate (ADC), were developed to specifically release cytotoxic payloads within targeted cells overexpressing cognate antigen receptors. Therefore, an αCD44(scFv)-SNAP-tag antibody fusion protein was engineered through genetic fusion of a single-chain antibody fragment (scFv) to a SNAPf-tag fusion protein, capable of self-conjugating with benzylguanine-modified light-sensitive near-infrared (NIR) phthalocyanine dye IRDye700DX (BG-IR700) or the small molecule toxin auristatin-F (BG-AURIF). Binding of the αCD44(scFv)-SNAPf-IR700 photoimmunoconjugate to antigen-positive cells was demonstrated by confocal microscopy and flow cytometry. By switching to NIR irradiation, CD44-expressing TNBC was selectively killed through induced phototoxic activities. Likewise, the αCD44(scFv)-SNAPf-AURIF immunoconjugate was able to selectively accumulate within targeted cells and significantly reduced cell viability through antimitotic activities at nano- to micromolar drug concentrations. This study provides an in vitro proof-of-concept for a future strategy to selectively destroy light-accessible superficial CD44-expressing TNBC tumors and their metastatic lesions which are inaccessible to therapeutic light.

Multifactoral immune modulation potentiates durable remission in multiple models of aggressive malignancy

Tumors typically lack canonical danger signals required to activate adaptive immunity and also frequently employ substantial immunomodulatory mechanisms that downregulate adaptive responses and contribute to escape from immune surveillance. Given the variety of mechanisms involved in shielding tumors from immune recognition, it is not surprising that single-agent immunomodulatory approaches have been largely unsuccessful in generating durable antitumor responses. Here we report a unique combination of immunomodulatory and cytostatic agents that recondition the tumor microenvironment and eliminate complex and/or poor-prognosis tumor types including the non-immunogenic 4T-1 model of TNBC, the aggressive MOC-2 model of HNSCC, and the high-risk MYCN-amplified model of neuroblastoma. A course of therapy optimized for TNBC cured a majority of tumors in both ectopic and orthotopic settings and eliminated metastatic spread in all animals tested at the highest doses. Immune responses were transferable between therapeutic donor and naïve recipient through adoptive transfer, and a sizeable abscopal effect on distant, untreated lesions could be demonstrated experimentally. Similar results were observed in HNSCC and neuroblastoma models, with characteristic remodeling of the tumor microenvironment documented in all model systems. scRNA-seq analysis implicated upregulation of innate immune responses and antigen presentation in tumor cells and the myeloid cell compartment as critical early events. This analysis also highlighted the potential importance of the autonomic nervous system in the governance of inflammatory processes. The data indicate that the targeting of multiple pathways and mechanisms of action can result in substantial synergistic antitumor effects and suggest follow-up in the neoadjuvant setting may be warranted.

Informed by Cancer Stem Cells of Solid Tumors: Advances in Treatments Targeting Tumor-Promoting Factors and Pathways

Cancer stem cells (CSCs) represent a subpopulation within tumors that promote cancer progression, metastasis, and recurrence due to their self-renewal capacity and resistance to conventional therapies. CSC-specific markers and signaling pathways highly active in CSCs have emerged as a promising strategy for improving patient outcomes. This review provides a comprehensive overview of the therapeutic targets associated with CSCs of solid tumors across various cancer types, including key molecular markers aldehyde dehydrogenases, CD44, epithelial cellular adhesion molecule, and CD133 and signaling pathways such as Wnt/β-catenin, Notch, and Sonic Hedgehog. We discuss a wide array of therapeutic modalities ranging from targeted antibodies, small molecule inhibitors, and near-infrared photoimmunotherapy to advanced genetic approaches like RNA interference, CRISPR/Cas9 technology, aptamers, antisense oligonucleotides, chimeric antigen receptor (CAR) T cells, CAR natural killer cells, bispecific T cell engagers, immunotoxins, drug-antibody conjugates, therapeutic peptides, and dendritic cell vaccines. This review spans developments from preclinical investigations to ongoing clinical trials, highlighting the innovative targeting strategies that have been informed by CSC-associated pathways and molecules to overcome therapeutic resistance. We aim to provide insights into the potential of these therapies to revolutionize cancer treatment, underscoring the critical need for a multi-faceted approach in the battle against cancer. This comprehensive analysis demonstrates how advances made in the CSC field have informed significant developments in novel targeted therapeutic approaches, with the ultimate goal of achieving more effective and durable responses in cancer patients.

Intratumoral IL15 Improves Efficacy of Near-Infrared Photoimmunotherapy

IL15 is a potent inducer of differentiation and proliferation of CD8+ T and natural killer (NK) cells, making it a promising candidate for cancer immunotherapy. However, limited efficacy of systemic monotherapy utilizing intravenous IL15 suggests the needs for alternative routes of administration or combination treatment with other therapies. Near-infrared photoimmunotherapy (NIR-PIT) is a highly selective anticancer treatment that elicits a massive release of tumor antigens and immunogenic signals. Here, we investigated whether intratumoral IL15 can enhance the effectiveness of cancer cell-targeted NIR-PIT using syngeneic murine tumor models. Intratumoral injection of IL15 was more effective than intraperitoneal IL15 in vivo in suppressing tumor growth and inducing intratumoral immune responses. When the efficacy of CD44-targeted NIR-PIT was compared in vivo between IL15-secreting MC38 (hIL15-MC38) and parental MC38 tumors, the hIL15-MC38/NIR-PIT group showed the best tumor growth inhibition and survival. In addition, the hIL15-MC38/NIR-PIT group showed significant dendritic cell maturation and significant increases in the number and Granzyme B expression of tumor-infiltrating CD8+ T, NK, and natural killer T cells compared with the treated parental line. Furthermore, intratumoral IL15 injection combined with CD44-targeted NIR-PIT showed significant tumor control in MC38 and Pan02-luc tumor models. In bilateral tumor models, CD44-targeted NIR-PIT in hIL15-MC38 tumors significantly suppressed the growth of untreated MC38 tumors, suggesting abscopal effects. Mice that achieved complete response after the combination therapy completely rejected later tumor rechallenge. In conclusion, local IL15 administration synergistically improves the efficacy of cancer cell-targeted NIR-PIT probably by inducing stronger anticancer immunity, indicating its potential as an anticancer treatment strategy.

Exploring animal models in oral cancer research and clinical intervention: A critical review

Cancer is a leading cause of death worldwide, but advances in treatment, early detection, and prevention have helped to reduce its impact. To translate cancer research findings into clinical interventions for patients, appropriate animal experimental models, particularly in oral cancer therapy, can be helpful. In vitro experiments using animal or human cells can provide insight into cancer's biochemical pathways. This review discusses the various animal models used in recent years for research and clinical intervention in oral cancer, along with their advantages and disadvantages. We highlight the advantages and limitations of the used animal models in oral cancer research and therapy by searching the terms of animal models, oral cancer, oral cancer therapy, oral cancer research, and animals to find all relevant publications during 2010-2023. Mouse models, widely used in cancer research, can help us understand protein and gene functions in vivo and molecular pathways more deeply. To induce cancer in rodents, xenografts are often used, but companion animals with spontaneous tumours are underutilized for rapid advancement in human and veterinary cancer treatments. Like humans with cancer, companion animals exhibit biological behaviour, treatment responses, and cytotoxic agent responses similar to humans. In companion animal models, disease progression is more rapid, and the animals have a shorter lifespan. Animal models allow researchers to study how immune cells interact with cancer cells and how they can be targeted specifically. Additionally, animal models have been extensively used in research on oral cancers, so researchers can use existing knowledge and tools to better understand oral cancers using animal models.

A Novel Anti-CD44 Variant 3 Monoclonal Antibody C44Mab-6 Was Established for Multiple Applications

Cluster of differentiation 44 (CD44) promotes tumor progression through the recruitment of growth factors and the acquisition of stemness, invasiveness, and drug resistance. CD44 has multiple isoforms including CD44 standard (CD44s) and CD44 variants (CD44v), which have common and unique functions in tumor development. Therefore, elucidating the function of each CD44 isoform in a tumor is essential for the establishment of CD44-targeting tumor therapy. We have established various anti-CD44s and anti-CD44v monoclonal antibodies (mAbs) through the immunization of CD44v3-10-overexpressed cells. In this study, we established C44Mab-6 (IgG1, kappa), which recognized the CD44 variant 3-encoded region (CD44v3), as determined via an enzyme-linked immunosorbent assay. C44Mab-6 reacted with CD44v3-10-overexpressed Chinese hamster ovary (CHO)-K1 cells (CHO/CD44v3-10) or some cancer cell lines (COLO205 and HSC-3) via flow cytometry. The apparent KD of C44Mab-6 for CHO/CD44v3-10, COLO205, and HSC-3 was 1.5 × 10-9 M, 6.3 × 10-9 M, and 1.9 × 10-9 M, respectively. C44Mab-6 could detect the CD44v3-10 in Western blotting and stained the formalin-fixed paraffin-embedded tumor sections in immunohistochemistry. These results indicate that C44Mab-6 is useful for detecting CD44v3 in various experiments and is expected for the application of tumor diagnosis and therapy.

Development of a Novel Anti-CD44 Variant 7/8 Monoclonal Antibody, C44Mab-34, for Multiple Applications against Oral Carcinomas

Cluster of differentiation 44 (CD44) has been investigated as a cancer stem cell (CSC) marker as it plays critical roles in tumor malignant progression. The splicing variants are overexpressed in many carcinomas, especially squamous cell carcinomas, and play critical roles in the promotion of tumor metastasis, the acquisition of CSC properties, and resistance to treatments. Therefore, each CD44 variant (CD44v) function and distribution in carcinomas should be clarified for the establishment of novel tumor diagnosis and therapy. In this study, we immunized mouse with a CD44 variant (CD44v3–10) ectodomain and established various anti-CD44 monoclonal antibodies (mAbs). One of the established clones (C44Mab-34; IgG1, kappa) recognized a peptide that covers both variant 7- and variant 8-encoded regions, indicating that C44Mab-34 is a specific mAb for CD44v7/8. Moreover, C44Mab-34 reacted with CD44v3–10-overexpressed Chinese hamster ovary-K1 (CHO) cells or the oral squamous cell carcinoma (OSCC) cell line (HSC-3) by flow cytometry. The apparent KD of C44Mab-34 for CHO/CD44v3–10 and HSC-3 was 1.4 × 10−9 and 3.2 × 10−9 M, respectively. C44Mab-34 could detect CD44v3–10 in Western blotting and stained the formalin-fixed paraffin-embedded OSCC in immunohistochemistry. These results indicate that C44Mab-34 is useful for detecting CD44v7/8 in various applications and is expected to be useful in the application of OSCC diagnosis and therapy.

Rational Design of a Self-Assembling High Performance Organic Nanofluorophore for Intraoperative NIR-II Image-Guided Tumor Resection of Oral Cancer

The first line of treatment for most solid tumors is surgical resection of the primary tumor with adequate negative margins. Incomplete tumor resections with positive margins account for over 75% of local recurrences and the development of distant metastases. In cases of oral cavity squamous cell carcinoma (OSCC), the rate of successful tumor removal with adequate margins is just 50-75%. Advanced real-time imaging methods that improve the detection of tumor margins can help improve success rates,overall safety, and reduce the cost. Fluorescence imaging in the second near-infrared (NIR-II) window has the potential to revolutionize the field due to its high spatial resolution, low background signal, and deep tissue penetration properties, but NIR-II dyes with adequate in vivo performance and safety profiles are scarce. A novel NIR-II fluorophore, XW-03-66, with a fluorescence quantum yield (QY) of 6.0% in aqueous media is reported. XW-03-66 self-assembles into nanoparticles (≈80 nm) and has a systemic circulation half-life (t_1/2 ) of 11.3 h. In mouse models of human papillomavirus (HPV)+ and HPV- OSCC, XW-03-66 outperformed indocyanine green (ICG), a clinically available NIR dye, and enabled intraoperative NIR-II image-guided resection of the tumor and adjacent draining lymph node with negative margins. In vitro and in vivo toxicity assessments revealed minimal safety concerns for in vivo applications.

Insight on nano drug delivery systems with targeted therapy in treatment of oral cancer

Oral cancer is a type of cancer that develops in the mouth and is one of the deadliest malignancies in the world. Currently surgical, radiation therapy, and chemotherapy are most common treatments. Better treatment and early detection strategies are required. Chemotherapeutic drugs fail frequently due to toxicity and poor tumor targeting. There are high chances of failure of chemotherapeutic drugs due to toxicity. Active, passive, and immunity-targeting techniques are devised for tumor-specific activity. Nanotechnology-based drug delivery systems are the best available solution and important for precise targeting. Nanoparticles, liposomes, exosomes, and cyclodextrins are nano-based carriers for drug delivery. Nanotechnology is being used to develop new techniques such as intratumoral injections, microbubble mediated ultrasonic therapy, phototherapies, and site-specific delivery. This systematic review delves into the details of such targeted and nano-based drug delivery systems in order to improve patient health and survival rates in oral 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.

Opening up new VISTAs: V-domain immunoglobulin suppressor of T cell activation (VISTA) targeted near-infrared photoimmunotherapy (NIR-PIT) for enhancing host immunity against cancers

V-domain immunoglobulin suppressor of T cell activation (VISTA) is an inhibitory immune checkpoint molecule that is broadly expressed on lymphoid and myeloid cells, including regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs). Near-infrared photoimmunotherapy (NIR-PIT) is a cancer treatment that utilizes an antibody-photoabsorber (IRDye 700DX NHS ester) conjugate to selectively kill target cells after the local application of NIR light. Depletion of VISTA-expressing cells in the tumor microenvironment (TME) using NIR-PIT could enhance anti-tumor immune responses by removing immune suppressive cells. The purpose of this study was to evaluate the anti-tumor efficacy of VISTA-targeted NIR-PIT using two murine tumor models, MC38-luc and LL2-luc. VISTA was expressed on T cells including Tregs and MDSCs in the TME of these tumors. In contrast, CD45 - cells, including cancer cells, did not express VISTA. VISTA-targeted NIR-PIT depleted VISTA-expressing cells ex vivo. In vivo VISTA-targeted NIR-PIT inhibited tumor progression and prolonged survival in both models. After VISTA-targeted NIR-PIT, augmented CD8 + T cell and dendritic cell activation were observed in regional lymph nodes. In conclusion, VISTA-targeted NIR-PIT can effectively treat tumors by decreasing VISTA-expressing immune suppressor cells in the TME. Local depletion of VISTA-expressing cells in the tumor bed using NIR-PIT is a promising new cancer immunotherapy for treating various types of tumors.

Circular RNA-related CeRNA network and prognostic signature for patients with oral squamous cell carcinoma

Background: Circular RNA (circRNA) has an important influence on oral squamous cell carcinoma (OSCC) progression as competing endogenous RNAs (ceRNAs). However, the link between ceRNAs and the OSCC immune microenvironment is unknown. The research aimed to find circRNAs implicated in OSCC carcinogenesis and progression and build a circRNA-based ceRNA network to create a reliable OSCC risk prediction model. Methods: The expression profiles of circRNA in OSCC tumors and normal tissues were assessed through RNA sequencing. From the TCGA database, clinicopathological data and expression patterns of microRNAs (miRNAs) and mRNAs were obtained. A network of circRNA-miRNA-mRNA ceRNA was prepared according to these differentially expressed RNAs and was analyzed through functional enrichment. Subsequently, based on the mRNA in the ceRNA network, the influence of the model on prognosis was then evaluated using a risk prediction model. Finally, considering survival, tumor-infiltrating immune cells (TICs), clinicopathological features, immunosuppressive molecules, and chemotherapy efficacy were analyzed. Results: Eleven differentially expressed circRNAs were found in cancer tissues relative to healthy tissues. We established a network of circRNA-miRNA-mRNA ceRNA, and the ceRNA network includes 123 mRNAs, six miRNAs, and four circRNAs. By the assessment of Genomes pathway and Kyoto Encyclopedia of Genes, it is found that in the cellular senescence, PI3K-AKT and mTOR signaling pathway mRNAs were mainly enrichment. An immune-related signature was created utilizing seven immune-related genes in the ceRNA network after univariate and multivariate analysis. The receiver operating characteristic of the nomogram exhibited satisfactory accuracy and predictive potential. According to a Kaplan-Meier analysis, the high-risk group's survival rate was signally lower than the group with low-risk. In addition, risk models were linked to clinicopathological characteristics, TICs, immune checkpoints, and antitumor drug susceptibility. Conclusion: The profiles of circRNAs expression of OSCC tissues differ significantly from normal tissues. Our study established a circRNA-associated ceRNA network associated with OSCC and identified essential prognostic genes. Furthermore, our proposed immune-based signature aims to help research OSCC etiology, prognostic marker screening, and immune response evaluation.

Treg-Dominant Tumor Microenvironment Is Responsible for Hyperprogressive Disease after PD-1 Blockade Therapy

Programmed cell death 1 (PD-1) blockade therapy can result in dramatic responses in some patients with cancer. However, about 15% of patients receiving PD-1 blockade therapy experience rapid tumor progression, a phenomenon termed "hyperprogressive disease" (HPD). The mechanism(s) underlying HPD has been difficult to uncover because HPD is challenging to reproduce in animal models. Near-infrared photoimmunotherapy (NIR-PIT) is a method by which specific cells in the tumor microenvironment (TME) can be selectively depleted without disturbing other cells in the TME. In this study, we partially depleted CD8+ T cells with NIR-PIT by targeting the CD8β antigen thereby temporarily changing the balance of T-cell subsets in two different syngeneic tumor models. PD-1 blockade in these models led to rapid tumor progression compared with controls. CD3ε+CD8α+/CD3ε+CD4+FoxP3+ (Teff/Treg) ratios in the PD-1 and NIR-PIT groups were lower than in controls. Moreover, in a bilateral tumor model, low-dose CD8β-targeted NIR-PIT with anti-PD-1 blockade showed rapid tumor progression only in the tumor exposed to NIR light. In this experiment CD8β-targeted NIR-PIT in the exposed tumor reduced local CD8+ T cells resulting in a regulatory T-cell (Treg)-dominant TME. In conclusion, this reports an animal model to simulate the Treg-dominant TME, and the data generated using the model suggest that HPD after PD-1 blockade therapy can be attributed, at least in part, to imbalances between effector T cells and Tregs in the TME.

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.

Comparison of the Effectiveness of IgG Antibody versus F(ab')2 Antibody Fragment in CTLA4-Targeted Near-Infrared Photoimmunotherapy

Near-infrared photoimmunotherapy (NIR-PIT) is a novel cancer treatment modality that utilizes antibody-photoabsorber conjugates (APCs) and selectively kills target cells after irradiation with NIR light. Originally, NIR-PIT was targeted against cancer cell surface antigens, but as it became clear that NIR-PIT induced a strong immune response, an effort was made to target selected immune cell populations in the tumor microenvironment to encourage an even stronger immune response. Thus, CD25-targeted NIR-PIT and cytotoxic T-lymphocyte associated protein 4 (CTLA4)-targeted NIR-PIT were developed to kill regulatory T cells (Tregs) in conjunction with cancer-cell-targeted NIR-PIT, in order to amplify the host immune response. It was found that CD25-targeted NIR-PIT, using an antibody with the Fc portion removed, led to better results than the unmodified anti-CD25 antibody-directed NIR-PIT presumably because of a negative effect on activated T cells. The aim of this study was to compare the efficacy of an antibody fragment [anti-CTLA4-F(ab')2] and a whole antibody (anti-CTLA4-IgG) for NIR-PIT. There was no significant difference in NIR-PIT-induced Treg killing between the anti-CTLA4-F(ab')2 and anti-CTLA4-IgG antibodies. Although both the antibody and the antibody fragment resulted in significant tumor growth inhibition, the antibody induced more robust CD8+ T cell activation in ipsilateral lymph nodes and was more effective compared to the antibody fragment. The slower clearance of the anti-CTLA4-IgG APC enhanced antitumor immunity by promoting T cell priming in lymph nodes. In conclusion, unlike the results with CD25 where modified antibodies produced superior results to unmodified antibodies, anti-CTLA4-IgG antibody-based NIR-PIT proved more effective in reducing tumor growth than anti-CTLA4-F(ab')2 antibody-based NIR-PIT.

Disialoganglioside GD2-Targeted Near-Infrared Photoimmunotherapy (NIR-PIT) in Tumors of Neuroectodermal Origin

Disialoganglioside (GD2) is a subtype of glycolipids that is highly expressed in tumors of neuroectodermal origins, such as neuroblastoma and osteosarcoma. Its limited expression in normal tissues makes GD2 a potential target for precision therapy. Several anti-GD2 monoclonal antibodies are currently in clinical use and have had moderate success. Near-infrared photoimmunotherapy (NIR-PIT) is a cancer therapy that arms antibodies with IRDye700DX (IR700) and then exposes this antibody-dye conjugate (ADC) to NIR light at a wavelength of 690 nm. NIR light irradiation induces a profound photochemical response in IR700, resulting in protein aggregates that lead to cell membrane damage and death. In this study, we examined the feasibility of GD2-targeted NIR-PIT. Although GD2, like other glycolipids, is only located in the outer leaflet of the cell membrane, the aggregates formation exerted sufficient physical force to disrupt the cell membrane and kill target cells in vitro. In in vivo studies, tumor growth was significantly inhibited after GD2-targeted NIR-PIT, resulting in prolonged survival. Following GD2-targeted NIR-PIT, activation of host immunity was observed. In conclusion, GD2-targeted NIR-PIT was similarly effective to the conventional protein-targeted NIR-PIT. This study demonstrates that membrane glycolipid can be a new target of NIR-PIT.

The mouse oral carcinoma (MOC) model: A 10-year retrospective on model development and head and neck cancer investigations

Preclinical models of cancer have long been paramount to understanding tumor development and advancing the treatment of cancer. Creating preclinical models that mimic the complexity and heterogeneity of human tumors is a key challenge in the advancement of cancer therapy. About ten years ago, we created the mouse oral carcinoma (MOC) cell line models that were derived from 7, 12-dimethylbenz(a) anthracene (DMBA)-induced mouse oral squamous cell cancers. This model has been used in numerous investigations, including studies on tumor biology and therapeutics. We have seen remarkable progress in cancer immunology in recent years, and these cell lines, which are syngeneic to C57BL/6 background, have also been used to study the anti-tumor immune response. Herein, we aim to review the MOC model from its development and characterization to its use in non-immunological and immunological preclinical head and neck squamous cell carcinoma (HNSCC) studies. Integrating and refining these MOC model studies and extending findings to other systems will provide crucial insights for translational approaches aimed at improving head and neck cancer treatment.

Mouse Models for Immune Checkpoint Blockade Therapeutic Research in Oral Cancer

The most prevalent oral cancer globally is oral squamous cell carcinoma (OSCC). The invasion of adjacent bones and the metastasis to regional lymph nodes often lead to poor prognoses and shortened survival times in patients with OSCC. Encouraging immunotherapeutic responses have been seen with immune checkpoint inhibitors (ICIs); however, these positive responses to monotherapy have been limited to a small subset of patients. Therefore, it is urgent that further investigations into optimizing immunotherapies are conducted. Areas of research include identifying novel immune checkpoints and targets and tailoring treatment programs to meet the needs of individual patients. Furthermore, the advancement of combination therapies against OSCC is also critical. Thus, additional studies are needed to ensure clinical trials are successful. Mice models are advantageous in immunotherapy research with several advantages, such as relatively low costs and high tumor growth success rate. This review paper divided methods for establishing OSCC mouse models into four categories: syngeneic tumor models, chemical carcinogen induction, genetically engineered mouse, and humanized mouse. Each method has advantages and disadvantages that influence its application in OSCC research. This review comprehensively surveys the literature and summarizes the current mouse models used in immunotherapy, their advantages and disadvantages, and details relating to the cell lines for oral cancer growth. This review aims to present evidence and considerations for choosing a suitable model establishment method to investigate the early diagnosis, clinical treatment, and related pathogenesis of OSCC.

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.

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.

miR-28-5p inhibits cholangiocarcinoma progression and predicts good prognosis of patients

Cholangiocarcinoma (CCA) is one of the most common hepatic and biliary malignancies. The overall five-year survival rate for cholangiocarcinoma is less than 15%. miR-28-5p has been reported to participate the development of various human cancer types. But whether miR-28-5p is associated with the clinical course of CCA patients has not been clarified. Herein, we observed that miR-28-5p was reduced in CCA tissues and predicts the poor prognosis of CCA patients. Treatment with the demethylating agent 5-aza-2'-deoxycytidine (5-AZA) restored miR-28-5p expression in CCA cell lines. Furthermore, up-regulated miR-28-5p inhibited CCA cells growth and metastasis. Mechanistically, miR-28-5p suppressed CCA cells growth and metastasis via directly targeting CD44 molecular. Specific CD44 special siRNA abrogated the discrepancy of the proliferation and metastasis capacity between miR-28-5p-overexpression CCA cells and their control cells, which further confirmed that CD44 was required in miR-28-5p-inhibited CCA cell growth and metastasis.

Advances in Head and Neck Cancer Pain

Head and neck cancer (HNC) affects over 890,000 people annually worldwide and has a mortality rate of 50%. Aside from poor survival, HNC pain impairs eating, drinking, and talking in patients, severely reducing quality of life. Different pain phenotype in patients (allodynia, hyperalgesia, and spontaneous pain) results from a combination of anatomical, histopathological, and molecular differences between cancers. Poor pathologic features (e.g., perineural invasion, lymph node metastasis) are associated with increased pain. The use of syngeneic/immunocompetent animal models, as well as a new mouse model of perineural invasion, provides novel insights into the pathobiology of HNC pain. Glial and immune modulation of the tumor microenvironment affect not only cancer progression but also pain signaling. For example, Schwann cells promote cancer cell proliferation, migration, and secretion of nociceptive mediators, whereas neutrophils are implicated in sex differences in pain in animal models of HNC. Emerging evidence supports the existence of a functional loop of cross-activation between the tumor microenvironment and peripheral nerves, mediated by a molecular exchange of bioactive contents (pronociceptive and protumorigenic) via paracrine and autocrine signaling. Brain-derived neurotrophic factor, tumor necrosis factor α, legumain, cathepsin S, and A disintegrin and metalloprotease 17 expressed in the HNC microenvironment have recently been shown to promote HNC pain, further highlighting the importance of proinflammatory cytokines, neurotrophic factors, and proteases in mediating HNC-associated pain. Pronociceptive mediators, together with nerve injury, cause nociceptor hypersensitivity. Oncogenic, pronociceptive mediators packaged in cancer cell-derived exosomes also induce nociception in mice. In addition to increased production of pronociceptive mediators, HNC is accompanied by a dampened endogenous antinociception system (e.g., downregulation of resolvins and µ-opioid receptor expression). Resolvin treatment or gene delivery of µ-opioid receptors provides pain relief in preclinical HNC models. Collectively, recent studies suggest that pain and HNC progression share converging mechanisms that can be targeted for cancer treatment and pain management.

Photoimmunotherapy: A New Paradigm in Solid Tumor Immunotherapy

In recent years, the incidence of cancer has been increasing worldwide. Conventional cancer treatments include surgery, chemotherapy, and radiation, which mostly kill tumor cells at the expense of normal and immune cells. Although immunotherapy is an accurate, rapid, efficient tumor immune treatment, it causes serious adverse reactions, such as cytokine release syndrome (CRS) and neurotoxicity. Therefore, there is an urgent need to develop an effective and nontoxic procedure for immunotherapy. The clinical combination of phototherapy and immunoadjuvant therapy can induce immunogenic cell death and enhance antigen presentation synergy. It also causes a systemic antitumor immune response to manage residual tumors and distant metastases. Photoimmunotherapy (PIT) is a tumor treatment combining phototherapy with immunotherapy based on injecting a conjugate photosensitizer (IR700) and a monoclonal antibody (mAb) to target an expressed antigen on the tumor surface. This combination can enhance the immune response ability, thus having a good effect on the treatment of residual tumor and metastatic cancer. In this review, we summarize the recent progress in photoimmunotherapy, including photoimmunoconjugate (PIC), the activation mechanism of immunogenic cell death (ICD), the combination therapy model, opportunities and prospects. Specifically, we aim to provide a promising clinical therapy for solid tumor clinical transformation.

Endoscopic Applications of Near-Infrared Photoimmunotherapy (NIR-PIT) in Cancers of the Digestive and Respiratory Tracts

Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed and promising therapy that specifically destroys target cells by irradiating antibody-photo-absorber conjugates (APCs) with NIR light. APCs bind to target molecules on the cell surface, and when exposed to NIR light, cause disruption of the cell membrane due to the ligand release reaction and dye aggregation. This leads to rapid cell swelling, blebbing, and rupture, which leads to immunogenic cell death (ICD). ICD activates host antitumor immunity, which assists in killing still viable cancer cells in the treated lesion but is also capable of producing responses in untreated lesions. In September 2020, an APC and laser system were conditionally approved for clinical use in unresectable advanced head and neck cancer in Japan, and are now routine in appropriate patients. However, most tumors have been relatively accessible in the oral cavity or neck. Endoscopes offer the opportunity to deliver light deeper within hollow organs of the body. In recent years, the application of endoscopic therapy as an alternative to surgery for the treatment of cancer has expanded, providing significant benefits to inoperable patients. In this review, we will discuss the potential applications of endoscopic NIR-PIT, especially in thoracic and gastrointestinal 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.

Triggering anti-GBM immune response with EGFR-mediated photoimmunotherapy

BACKGROUND

Surgical resection followed by chemo-radiation postpones glioblastoma (GBM) progression and extends patient survival, but these tumours eventually recur. Multimodal treatment plans combining intraoperative techniques that maximise tumour excision with therapies aiming to remodel the immunologically cold GBM microenvironment could improve patients' outcomes. Herein, we report that targeted photoimmunotherapy (PIT) not only helps to define tumour location and margins but additionally promotes activation of anti-GBM T cell response.

METHODS

EGFR-specific affibody molecule (ZEGFR:03115) was conjugated to IR700. The response to ZEGFR:03115-IR700-PIT was investigated in vitro and in vivo in GBM cell lines and xenograft model. To determine the tumour-specific immune response post-PIT, a syngeneic GBM model was used.

RESULTS

In vitro findings confirmed the ability of ZEGFR:03115-IR700 to produce reactive oxygen species upon light irradiation. ZEGFR:03115-IR700-PIT promoted immunogenic cell death that triggered the release of damage-associated molecular patterns (DAMPs) (calreticulin, ATP, HSP70/90, and HMGB1) into the medium, leading to dendritic cell maturation. In vivo, therapeutic response to light-activated conjugate was observed in brain tumours as early as 1 h post-irradiation. Staining of the brain sections showed reduced cell proliferation, tumour necrosis, and microhaemorrhage within PIT-treated tumours that corroborated MRI T2*w acquisitions. Additionally, enhanced immunological response post-PIT resulted in the attraction and activation of T cells in mice bearing murine GBM brain tumours.

CONCLUSIONS

Our data underline the potential of ZEGFR:03115-IR700 to accurately visualise EGFR-positive brain tumours and to destroy tumour cells post-conjugate irradiation turning an immunosuppressive tumour environment into an immune-vulnerable one.

Immunotherapy of Cancer by Targeting Regulatory T cells

Regulatory T (Treg) cells maintain immune homeostasis by inhibiting abnormal/overactive immune responses to both autogenic and nonautogenic antigens. Treg cells play an important role in immune tolerance, autoimmune diseases, infectious diseases, organ transplantation, and tumor diseases. Treg cells have two functional characteristics: T cell anergy and immunosuppression. Treg cells remain immune unresponsive to high concentrations of interleukin-2 and anti-CD3 monoclonal antibodies. In addition, the activation of Treg cells after TCR-mediated signal stimulation inhibits the activation and proliferation of effector T cells. In the process of tumor development, Treg cells accumulate locally in the tumor and lead to tumor escape by inducing anergy and immunosuppression. It is believed that targeted elimination of Treg cells can activate tumor-specific effector T cells and improve the efficiency of cancer immunotherapy. Therefore, inhibition/clearance of Treg cells is a promising strategy for enhancing antitumor immunity. Here, we review studies of cancer immunotherapies targeting Treg cells.

Retrospective analysis of the preparation and application of immunotherapy in cancer treatment (Review)

Monoclonal antibody technology plays a vital role in biomedical and immunotherapy, which greatly promotes the study of the structure and function of genes and proteins. To date, monoclonal antibodies have gone through four stages: murine monoclonal antibody, chimeric monoclonal antibody, humanised monoclonal antibody and fully human monoclonal antibody; thousands of monoclonal antibodies have been used in the fields of biology and medicine, playing a special role in the pathogenesis, diagnosis and treatment of disease. In this review, we compare the advantages and disadvantages of hybridoma technology, phage display technology, ribosome display technology, transgenic mouse technology, single B cell monoclonal antibody generation technologies, and forecast the promising applications of these technologies in clinical medicine, disease diagnosis and tumour treatment.

CD29 targeted near-infrared photoimmunotherapy (NIR-PIT) in the treatment of a pigmented melanoma model

Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed cancer treatment that utilizes an antibody-photoabsorber-conjugate (AbPC) combined with NIR light. The AbPC is injected and binds to the tumor whereupon NIR light irradiation causes a photochemical reaction that selectively kills cancer cells. NIR-PIT is ideal for surface-located skin cancers such as melanoma. However, there is concern that the pigment in melanoma lesions could interfere with light delivery, rendering treatment ineffective. We investigated the efficacy of CD29- and CD44-targeted NIR-PIT (CD29-PIT and CD44-PIT, respectively) in the B16 melanoma model, which is highly pigmented. While CD29-PIT and CD44-PIT killed B16 cells invitro and invivo, CD29-PIT suppressed tumor growth more efficiently. Ki67 expression showed that cells surviving CD29-PIT were less proliferative, suggesting that CD29-PIT was selective for more proliferative cancer cells. CD29-PIT did not kill immune cells, whereas CD44-PIT killed both T and NK cells and most myeloid cells, including DCs, which could interfere with the immune response to NIR-PIT. The addition of anti-CTLA4 antibody immune checkpoint inhibitor (ICI) to CD29-PIT increased the infiltration of CD8 T cells and enhanced tumor suppression with prolonged survival. Such effects were less prominent when the anti-CTLA4 ICI was combined with CD44-PIT. The preservation of immune cells in the tumor microenvironment (TME) after CD29-PIT likely led to a better response when combined with anti-CTLA4 treatment. We conclude that NIR-PIT can be performed in pigmented melanomas and that CD29 is a promising target for NIR-PIT, which is amenable to combination therapy with other immunotherapies.

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.

An excellent antibacterial and high self-adhesive hydrogel can promote wound fully healing driven by its shrinkage under NIR

The lacks of antibacterial properties, low adhesion and delayed wound healing of the hydrogel wound dressings limit their applications in wound treatment. To resolve these, a novel hydrogel composed of polydopamine (PDA), Ag and graphene oxide (GO) is fabricated for wound dressing via the chemical crosslinking of N-isopropylacrylamide (NIPAM) and N,N'-methylene bisacrylamide (BIS). The prepared hydrogel containing PDA@Ag5GO1 (Ag5GO1 denotes the mass ratio between Ag and GO is 5:1) exhibits effective antibacterial properties and high inhibition rate against E. coli and S. aureus. It shows high adhesion ability to various substrate materials, implying a simpler method to the wound obtained by self-fixing rather than suturing. More important, it can produce strong contractility under the irradiation of near-infrared light (NIR), exerting a centripetal force that helps accelerate wound healing. Thus, the hydrogel containing a high concentration PDA@Ag5GO1 irradiated by NIR can completely repair the wound defect (1.0 × 1.0 cm²) within 15 days, the wound healing rate can reach 100%, which was far higher than other groups. Taken together, the new hydrogel with excellent antibacterial, high adhesion and strong contractility will subvert the traditional treatment methods on wound defect, extending its new application range in wound dressing.

Simultaneously Combined Cancer Cell- and CTLA4-Targeted NIR-PIT Causes a Synergistic Treatment Effect in Syngeneic Mouse Models

Near-infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that utilizes antibody-IRDye700DX (IR700) conjugates. The clinical use of NIR-PIT has recently been approved in Japan for patients with inoperable head and neck cancer targeting human epidermal growth factor receptor (hEGFR). Previously, cytotoxic T-lymphocyte antigen 4 (CTLA4)-targeted NIR-PIT has been shown to strongly inhibit tumor progression and prolonged survival was seen in different tumor models due to enhanced T-cell-mediated antitumor immunity. In this study, combined NIR-PIT targeting CTLA4 expressing cells and cancer cells was investigated in four tumor models including a newly established hEGFR-expressing murine oropharyngeal cancer cell (mEERL-hEGFR). While single molecule-targeted therapy (NIR-PIT targeting hEGFR or CTLA4) did not inhibit tumor progression in poorly immunogenic mEERL-hEGFR tumor, dual (CTLA4/hEGFR)-targeted NIR-PIT significantly suppressed tumor growth and prolonged survival resulting in a 38% complete response rate. After the dual-targeted NIR-PIT, depletion of CTLA4 expressing cells, which were mainly regulatory T cells (Tregs), and an increase in the CD8⁺/Treg ratio in the tumor bed were observed, suggesting enhanced host antitumor immunity. Furthermore, dual-targeted NIR-PIT showed antitumor immunity in distant untreated tumors of the same type. Thus, simultaneous cancer cell-targeted NIR-PIT and CTLA4-targeted NIR-PIT is a promising new cancer therapy strategy, especially in poorly immunogenic tumors where NIR-PIT monotherapy is suboptimal.

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 for cancers: A translational perspective

Near-infrared photoimmunotherapy (NIR-PIT) is a newly-developed, highly-selective cancer treatment, which utilizes a monoclonal antibody conjugated to a photoabsorbing dye, IRDye700DX (IR700). The antibody conjugate is injected into the patient and accumulates in the tumour. Within 24 h of injection the tumour is exposed to NIR light which activates the conjugate and causes rapid, selective cancer cell death. A global phase III clinical trial of NIR-PIT in recurrent head and neck squamous cell cancer (HNSCC) patients is currently underway. Conditional clinical approval for NIR-PIT in recurrent HNSCC has been granted in Japan as of September 2020. Not only does NIR-PIT induce highly selective and immediate cancer cell killing, but it also stimulates highly active anti-tumour immunity. While monotherapy with NIR-PIT has proven effective it is likely that combinations with immune-checkpoint inhibitors or additional NIR-PIT targeting immune suppressive cells in the tumour microenvironment will further improve results. In this review, we discuss the translational aspects of NIR-PIT especially in HNSCC, and potential future applications.

Endoscopic near-infrared photoimmunotherapy in an orthotopic head and neck cancer model

Near-infrared photoimmunotherapy (NIR-PIT) is a cell selective cancer therapy that uses an antibody-photoabsorber (IRDye700DX, IR700) conjugate (APC) and NIR light. NIR-PIT targeting epidermal growth factor receptor (EGFR) in head and neck cancer (HNC) was conditionally approved in Japan in 2020. APC-bound tumors can be detected using endoscopic fluorescence imaging, whereas NIR light can be delivered using endoscopic fiber optics. The aims of this study were: (1) to assess the feasibility of endoscopic NIR-PIT in an orthotopic HNC model using a CD44-expressing MOC2-luc cell line; and (2) to evaluate quantitative fluorescence endoscopic imaging prior to and during NIR-PIT. The results were compared in 3 experimental groups: (1) untreated controls, (2) APC injection without light exposure (APC-IV), and (3) APC injection followed by NIR light exposure (NIR-PIT). APC injected groups showed significantly higher fluorescence signals for IR700 compared with the control group prior to therapeutic NIR light exposure, and the fluorescence signal significantly decreased in the NIR-PIT group after light exposure. After treatment, the NIR-PIT group showed significantly attenuated bioluminescence compared with the control and the APC-IV groups. Histology demonstrated diffuse necrotic death of the cancer cells in the NIR-PIT group alone. In conclusion, endoscopically delivered light combined with quantitative fluorescence imaging can be used to "see and treat" HNC. This method could also be applied to other types of cancer approachable with endoscopy.

Evaluation of In Vitro Phototoxicity of a Minibody-IR700 Conjugate Using Cell Monolayer and Multicellular Tumor Spheroid Models

Photodynamic therapy (PDT) is a treatment strategy that utilizes photosensitizers (PSs) and light of a specific wavelength to kill cancer cells. However, limited tumor specificity is still a drawback for the clinical application of PDT. To increase the therapeutic efficacy and specificity of PDT, a novel human minibody (MS5) that recognizes a cell surface receptor expressed on various cancer cells was labeled with the hydrophilic phthalocyanine PS IR700 to generate an MS5-IR700 conjugate that is activated by near-infrared (NIR) light. The phototoxicity of the conjugate was mainly tested against the PC3 prostate cancer cell line. The MS5-IR700 conjugate killed PC3 cells after NIR light irradiation as compared to untreated cells or cells treated with IR700 alone. Time-course analysis of cell viability revealed a high percentage of cell death during the first hour in PC3 cells exposed to the MS5-IR700 conjugate and NIR light irradiation. After irradiation, the MS5-IR700 conjugate-treated PC3 cells displayed cellular swelling, round shape, and rupture of the cell and nuclear membranes. In a co-culture model, the MS5-IR700 conjugate killed MS5-positive Ramos lymphoma cells specifically, while leaving MS5-negative cells unaffected. In line with the data obtained with the monolayer cultures, the MS5-IR700 conjugate also killed PC3 cancer cell spheroids. The treatment induced relocation of heat shock protein 70 and calreticulin to the cell surface, implying the induction of immunogenic cell death. Overall, the data suggest that the developed MS5-IR700 conjugate is a promising therapeutic agent that warrants further preclinical studies.

Therapeutic Potential of Antibody-Drug Conjugate-Based Therapy in Head and Neck Cancer: A Systematic Review

BACKGROUND

Antibody-drug conjugates (ADCs) are designed to deliver potent cytotoxic agents into tumor tissues. During the last two decades, a plethora of ADCs have been successfully developed and used for several indications, including hematologic and solid tumors. In this work, we systematically reviewed the progress in ADC development for the treatment of HNC.

METHODS

This review was registered in PROSPERO database. A comprehensive search was conducted following PRISMA guidelines and using PubMed, Scopus and Web of Science database.

RESULTS

In total, 19 studies were included. Due to the significant heterogeneity of the outcome measures, meta-analysis was not performed, and data were summarized in tables. HNC results are poorly represented in the cohorts of completed clinical trials; published data are mostly focused on safety evaluation rather than efficacy of ADCs.

CONCLUSIONS

Although several novel agents against a wide range of different antigens were investigated, showing promising results at a preclinical level, most of the targets reported in this review are not specific for HNC; hence, the development of ADCs tailored for the HNC phenotype could open up new therapeutic perspectives. Moreover, the results from the present systematic review call attention to how limited is the application of current clinical trials in HNC.

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.

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 (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.

FLASH Proton Pencil Beam Scanning Irradiation Minimizes Radiation-Induced Leg Contracture and Skin Toxicity in Mice

Simple Summary

Dose and efficacy of radiation therapy are limited by the toxicity to normal tissue adjacent to the treated tumor region. Recently, ultra-high dose rate radiotherapy (FLASH radiotherapy) has shown beneficial reduction of normal tissue damage while preserving similar tumor efficacy with electron, photon and scattered proton beam irradiation in preclinical models. Proton therapy is increasingly delivered by pencil beam scanning (PBS) technology, and we therefore set out to test PBS FLASH radiotherapy on normal tissue toxicity and tumor control in vivo in mouse using a clinical proton delivery system. This validation of the FLASH normal tissue-sparing hypothesis with a clinical delivery system provides supporting data for PBS FLASH radiotherapy and its potential role in improving radiotherapy outcomes.

Abstract

Ultra-high dose rate radiation has been reported to produce a more favorable toxicity and tumor control profile compared to conventional dose rates that are used for patient treatment. So far, the so-called FLASH effect has been validated for electron, photon and scattered proton beam, but not yet for proton pencil beam scanning (PBS). Because PBS is the state-of-the-art delivery modality for proton therapy and constitutes a wide and growing installation base, we determined the benefit of FLASH PBS on skin and soft tissue toxicity. Using a pencil beam scanning nozzle and the plateau region of a 250 MeV proton beam, a uniform physical dose of 35 Gy (toxicity study) or 15 Gy (tumor control study) was delivered to the right hind leg of mice at various dose rates: Sham, Conventional (Conv, 1 Gy/s), Flash60 (57 Gy/s) and Flash115 (115 Gy/s). Acute radiation effects were quantified by measurements of plasma and skin levels of TGF-β1 and skin toxicity scoring. Delayed irradiation response was defined by hind leg contracture as a surrogate of irradiation-induced skin and soft tissue toxicity and by plasma levels of 13 different cytokines (CXCL1, CXCL10, Eotaxin, IL1-beta, IL-6, MCP-1, Mip1alpha, TNF-alpha, TNF-beta, VEGF, G-CSF, GM-CSF and TGF- β1). Plasma and skin levels of TGF-β1, skin toxicity and leg contracture were all significantly decreased in FLASH compared to Conv groups of mice. FLASH and Conv PBS had similar efficacy with regards to growth control of MOC1 and MOC2 head and neck cancer cells transplanted into syngeneic, immunocompetent mice. These results demonstrate consistent delivery of FLASH PBS radiation from 1 to 115 Gy/s in a clinical gantry. Radiation response following delivery of 35 Gy indicates potential benefits of FLASH versus conventional PBS that are related to skin and soft tissue toxicity.

Fibroblast activation protein targeted near infrared photoimmunotherapy (NIR PIT) overcomes therapeutic resistance in human esophageal cancer

Cancer-associated fibroblasts (CAFs) have an important role in the tumor microenvironment. CAFs have the multifunctionality which strongly support cancer progression and the acquisition of therapeutic resistance by cancer cells. Near-infrared photoimmunotherapy (NIR-PIT) is a novel cancer treatment that uses a highly selective monoclonal antibody (mAb)-photosensitizer conjugate. We developed fibroblast activation protein (FAP)-targeted NIR-PIT, in which IR700 was conjugated to a FAP-specific antibody to target CAFs (CAFs-targeted NIR-PIT: CAFs-PIT). Thus, we hypothesized that the control of CAFs could overcome the resistance to conventional chemotherapy in esophageal cancer (EC). In this study, we evaluated whether EC cell acquisition of stronger malignant characteristics and refractoriness to chemoradiotherapy are mediated by CAFs. Next, we assessed whether the resistance could be rescued by eliminating CAF stimulation by CAFs-PIT in vitro and in vivo. Cancer cells acquired chemoradiotherapy resistance via CAF stimulation in vitro and 5-fluorouracil (FU) resistance in CAF-coinoculated tumor models in vivo. CAF stimulation promoted the migration/invasion of cancer cells and a stem-like phenotype in vitro, which were rescued by elimination of CAF stimulation. CAFs-PIT had a highly selective effect on CAFs in vitro. Finally, CAF elimination by CAFs-PIT in vivo demonstrated that the combination of 5-FU and NIR-PIT succeeded in producing 70.9% tumor reduction, while 5-FU alone achieved only 13.3% reduction, suggesting the recovery of 5-FU sensitivity in CAF-rich tumors. In conclusion, CAFs-PIT could overcome therapeutic resistance via CAF elimination. The combined use of novel targeted CAFs-PIT with conventional anticancer treatments can be expected to provide a more effective and sensible treatment strategy.

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 for Cancers of the Gastrointestinal Tract

BACKGROUND

Cancers of the gastrointestinal (GI) tract are the common leading cause of cancer-related death in the world. Recent advances in cancer therapies such as intensive multidrug chemotherapy and molecular targeted treatment have improved therapeutic efficacy; however, the outcomes are not satisfied. Moreover, these therapies also cause severe side effects. New type of cancer therapies is urgently needed to improve the outcomes and to reduce side effects of GI tract cancers.

SUMMARY

This account is a comprehensive review article on the newly developed, photochemistry-based cancer therapy named as near-infrared photoimmunotherapy (NIR-PIT). NIR-PIT is a highly selective tumor treatment that employs an antibody-photoabsorber conjugate, which is activated by near-infrared light. A world-wide phase 3 clinical trial of NIR-PIT against recurrent head and neck cancer patients is currently underway. NIR-PIT differs from conventional cancer therapies such as surgery, chemotherapy, and radiation in its selectivity for killing cancer cells and cells treated with NIR-PIT leading to immunogenic cell death. Preclinical research in animals with combining cancer-targeting NIR-PIT and other cancer immunotherapies could lead to responses not only in local tumor but also in distant metastases. NIR-PIT also leads to an immediate and dramatic increase in vascular permeability after therapy. From these aspects, NIR-PIT appears to be a promising new form of cancer therapy. NIR-PIT could be readily translated into clinical use for virtually any cancers in the near future provided suitable humanized antibodies are available. Here, we describe the specific advantages and applications of NIR-PIT in the GI tract. Key Messages: We believe that NIR-PIT with NIR excitation light, which can be delivered via a fiber optic diffuser through endoscopes, is a promising method for a new treatment of GI cancers.

Increased Immunogenicity of a Minimally Immunogenic Tumor after Cancer-Targeting Near Infrared Photoimmunotherapy

Near-infrared photoimmunotherapy (NIR-PIT) is a highly selective cancer treatment that employs an antibody photoabsorber conjugate (APC) composed of a targeting monoclonal antibody (mAb) conjugated with a photoactivatable phthalocyanine-derivative dye. Once injected and allowed to bind to a tumor, the APC is activated by local near-infrared light which kills cancer cells and induces a strong immune response in the tumor microenvironment by unmasking of new tumor antigens emerging from damaged tumor cells. Due to its ability to incite an immune reaction, even in poorly immunogenic tumors, NIR-PIT has the potential to enhance immunogenicity in tumors especially after immune checkpoint inhibition. In this study, we employ a poorly immunogenic MOC2-luc syngeneic tumor model and evaluate the efficacy of cancer-targeting CD44-targeted NIR-PIT. Increased infiltration of CD8+ T cells observed after NIR-PIT suggested an enhanced immune environment. Next, we evaluated tumor progression and survival after the combination of CD44-targeted NIR-PIT and short-term administration of an anti-PD1 immune checkpoint inhibitor (ICI) to further activate CD8+ T cells. Additionally, in mice in which the tumors were eradicated by this combination therapy, a re-challenge with fresh MOC2-luc cells demonstrated failure of tumor implantation implying acquired long-term immunity against the cancer cells. Combination therapy decreased tumor progression and prolonged survival significantly. Therefore, we concluded that NIR-PIT was able to convert a minimally immunogenic tumor unresponsive to anti-PD-1 ICI into a highly immunogenic tumor responsive to anti-PD-1 ICI, and this therapy was capable of inducing long-term immunity against the treated cancer.

Ligand-Targeted Delivery of Photosensitizers for Cancer Treatment

Photodynamic therapy (PDT) is a promising cancer treatment which involves a photosensitizer (PS), light at a specific wavelength for PS activation and oxygen, which combine to elicit cell death. While the illumination required to activate a PS imparts a certain amount of selectivity to PDT treatments, poor tumor accumulation and cell internalization are still inherent properties of most intravenously administered PSs. As a result, common consequences of PDT include skin photosensitivity. To overcome the mentioned issues, PSs may be tailored to specifically target overexpressed biomarkers of tumors. This active targeting can be achieved by direct conjugation of the PS to a ligand with enhanced affinity for a target overexpressed on cancer cells and/or other cells of the tumor microenvironment. Alternatively, PSs may be incorporated into ligand-targeted nanocarriers, which may also encompass multi-functionalities, including diagnosis and therapy. In this review, we highlight the major advances in active targeting of PSs, either by means of ligand-derived bioconjugates or by exploiting ligand-targeting nanocarriers.