Spatially selective depletion of tumor-associated regulatory T cells with near-infrared photoimmunotherapy

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.

Antitumor host immunity enhanced by near-infrared photoimmunotherapy

Near-infrared photoimmunotherapy (NIR-PIT) is a novel antitumor therapy that selectively kills cancer cells by NIR light-triggered photochemical reaction of IRDye700DX within Ab-photoabsorber conjugates (APCs). NIR-PIT induces immunogenic cell death, causing immune cell migration between the tumor and tumor-draining lymph nodes, and expanding multiclonal tumor-infiltrating CD8+ T cells. Crucially, the cytotoxic effects of NIR-PIT are limited to cancer cells, sparing immune cells such as antigen-presenting cells and T cells, which are key players in boosting antitumor host immunity. By modifying the Ab used in APC synthesis, NIR-PIT can be repurposed to target and deplete noncancerous immunosuppressive cells including regulatory T cells, myeloid-derived suppressor cells, and cancer-associated fibroblasts in the tumor microenvironment. Immunosuppressive cell targeted NIR-PIT strongly potentiates antitumor host immunity, including the induction of abscopal effects and the development of immune memory. Furthermore, antitumor immune responses and therapeutic efficacy are synergistically enhanced when NIR-PIT is combined with other immune-activating treatments, such as interleukin-15 and immune checkpoint inhibitors. These new findings make NIR-PIT a valuable tool in the evolving landscape of cancer immunotherapy. This review explains the role of NIR-PIT in activating antitumor host immunity.

The role of interventional radiology and molecular imaging for near infrared photoimmunotherapy

Near infrared photoimmunotherapy (NIR-PIT) is a recently approved cancer therapy for recurrent head and neck cancer. It involves the intravenous administration of an antibody-photoabsorber (IRDye700DX: IR700) conjugate (APC) to target cancer cells, followed 24 h later by exposure to near infrared light to activate cell-specific cytotoxicity. NIR-PIT selectively targets cancer cells for destruction and activates a strong anticancer host immunity. The fluorescent signal emitted by IR700 enables the visualization of the APC in vivo using fluorescence imaging. Similarly, the activation of IR700 during therapy can be monitored by loss of fluorescence. NIR-PIT can be used with a variety of antibodies and therefore, a variety of cancer types. However, in most cases, NIR-PIT requires direct light exposure only achieved with interstitial diffuser light fibers that are placed with image-guided interventional needle insertion. In addition, the unique nature of NIR-PIT cell death, means that metabolic molecular imaging techniques such as PET and diffusion MRI can be used to assess therapeutic outcomes. This mini-review focuses on the potential implications of NIR-PIT for interventional radiology and therapeutic monitoring.

Near-infrared Photoimmunotherapy Targeting Cancer-Associated Fibroblasts in Patient-Derived Xenografts Using a Humanized Anti-Fibroblast Activation Protein Antibody

Esophageal cancer remains a highly aggressive malignancy with a poor prognosis, despite ongoing advancements in treatments such as immunotherapy. The tumor microenvironment, particularly cancer-associated fibroblasts (CAF), plays a crucial role in driving the aggressiveness of esophageal cancer. In a previous study utilizing human-derived xenograft models, we successfully developed a novel cancer treatment that targeted CAFs with near-infrared photoimmunotherapy (NIR-PIT), as an adjuvant therapy. In this study, we sought to translate our findings toward clinical practice by employing patient-derived xenograft (PDX) models and utilizing humanized mAbs, specifically sibrotuzumab, which is an antihuman fibroblast activation protein (FAP) Ab and already being investigated in clinical trials as monotherapy. PDX models derived from patients with esophageal cancer were effectively established, preserving the expression of key biomarkers such as EGFR and FAP, as observed in primary tumors. The application of FAP-targeted NIR-PIT using sibrotuzumab, conjugated with the photosensitizer IR700DX, exhibited precise binding and selective elimination of FAP-expressing fibroblasts in vitro. Notably, in our in vivo investigations using both cell line-derived xenograft and PDX models, FAP-targeted NIR-PIT led to significant inhibition of tumor progression compared with control groups, all without inducing adverse events such as weight loss. Immunohistologic assessments revealed a substantial reduction in CAFs exclusively within the tumor microenvironment of both models, further supporting the efficacy of our approach. Thus, our study demonstrates the potential of CAF-targeted NIR-PIT employing sibrotuzumab as a promising therapeutic avenue for the clinical treatment of patients with esophageal cancer.

Photoimmunotheranostics of epithelioid sarcoma by targeting CD44 or EGFR

Epithelioid sarcoma (ES) is a rare soft tissue neoplasm with high recurrence rates. Wide surgical resection remains the only potential curative treatment. ES presents most commonly on the fingers, hands and forearm, making light-based cancer cell-targeted therapies such as near-infrared photoimmunotherapy (NIR-PIT) that is target-specific, but with limited penetration depth, suitable for ES treatment. We established that CD44 and EGFR were overexpressed in ES patient samples and in the VA-ES-BJ human ES cell line. NIR-PIT of VA-ES-BJ cells using antibody photosensitizer conjugates, prepared by conjugating a CD44 or EGFR monoclonal antibody to the photosensitizer IR700, confirmed that NIR-PIT with both conjugates resulted in cell death. Neither treatment with NIR light alone nor treatment with the conjugates but without NIR light were effective. CD44-IR700-PIT resulted in greater cell death than EGFR-IR700-PIT, consistent with the increased expression of CD44 by VA-ES-BJ cells. In tumors, EGFR-IR700 exhibited a higher tumor-to-normal ratio, as determined by in vivo fluorescence imaging, and a higher anti-tumor growth effect, compared to CD44-IR700. No antitumor effect of the EGFR antibody or the photosensitizer conjugate alone was observed in vivo. Our data support evaluating the use of EGFR-IR700-PIT in the management of ES for detecting and eliminating ES cells in surgical margins, and in the treatment of superficial recurrent tumors.

The fusion of light and immunity: Advancements in photoimmunotherapy for melanoma

Metastatic melanoma is an aggressive skin cancer with high mortality and recurrence rates. Despite the clinical success of recent immunotherapy approaches, prevailing resistance rates necessitate the continued development of novel therapeutic options. Photoimmunotherapy (PIT) is emerging as a promising immunotherapy strategy that uses photodynamic therapy (PDT) to unleash systemic immune responses against tumor sites while maintaining the superior tumor-specificity and minimally invasive nature of traditional PDT. In this review, we discuss recent advances in PIT and strategies for the management of melanoma using PIT. PIT can strongly induce immunogenic cell death, inviting the concomitant application of immune checkpoint blockade or adoptive cell therapies. PIT can also be leveraged to selectively remove the suppressive immune populations associated with immunotherapy resistance. The modular nature of PIT therapy design combined with the potential for patient-specific antigen selection or drug co-delivery makes PIT an alluring option for future personalized melanoma care.

Genetically evaluating the causal role of peripheral immune cells in colorectal cancer: a two-sample Mendelian randomization study

BACKGROUND

Investigating novel therapeutic strategies for colorectal cancer (CRC) is imperative. However, there is limited research on the use of drugs to target peripheral blood immune cells in this context. To address this gap, we performed a two-sample Mendelian randomization (MR) analysis to identify potential therapeutic targets for CRC.

METHODS

We applied two-sample MR to identify the causal relationship between peripheral blood immune cells and CRC. GWAS data were obtained from the IEU OPEN GWAS project. Based on the implications from the MR results, we conducted a comprehensive database search and genetic analysis to explore potential underlying mechanisms. We predicted miRNAs for each gene and employed extensive research for potential therapeutic applications.

RESULTS

We have identified causal associations between two peripheral immune cells and colorectal cancer. Activated & resting Treg %CD4 + cell was positively associated with the risks of CRC, while DN (CD4-CD8-) %leukocyte cell exhibited a protective role in tumor progression. NEK7 (NIMA related kinase 7) and LHX9 (LIM homeobox 9) expressed in Treg cells were positively associated with CRC risks and may play a vital role in carcinogenesis.

CONCLUSIONS

This study identified causal relationship between peripheral immune cell and CRC. Treg and DN T cells were implicated to own promoting and inhibiting effects on CRC progression respectively. NEK7 and LHX9 in Treg cells were identified as potential biotarget for antitumor therapies.

Near-infrared duocarmycin photorelease from a Treg-targeted antibody-drug conjugate improves efficacy of PD-1 blockade in syngeneic murine tumor models

Regulatory T cells (Tregs) play a crucial role in mediating immunosuppression in the tumor microenvironment. Furthermore, Tregs contribute to the lack of efficacy and hyperprogressive disease upon Programmed cell death protein 1 (PD-1) blockade immunotherapy. Thus, Tregs are considered a promising therapeutic target, especially when combined with PD-1 blockade. However, systemic depletion of Tregs causes severe autoimmune adverse events, which poses a serious challenge to Treg-directed therapy. Here, we developed a novel treatment to locally and predominantly damage Tregs by near-infrared duocarmycin photorelease (NIR-DPR). In this technology, we prepared anti-CD25 F(ab')2 conjugates, which site-specifically uncage duocarmycin in CD25-expressing cells upon exposure to NIR light. In vitro, CD25-targeted NIR-DPR significantly increased apoptosis of CD25-expressing HT2-A5E cells. When tumors were irradiated with NIR light in vivo, intratumoral CD25+ Treg populations decreased and Ki-67 and Interleukin-10 expression was suppressed, indicating impaired functioning of intratumoral CD25+ Tregs. CD25-targeted NIR-DPR suppressed tumor growth and improved survival in syngeneic murine tumor models. Of note, CD25-targeted NIR-DPR synergistically enhanced the efficacy of PD-1 blockade, especially in tumors with higher CD8+/Treg PD-1 ratios. Furthermore, the combination therapy induced significant anti-cancer immunity including maturation of dendritic cells, extensive intratumoral infiltration of cytotoxic CD8+ T cells, and increased differentiation into CD8+ memory T cells. Altogether, CD25-targeted NIR-DPR locally and predominantly targets Tregs in the tumor microenvironment and synergistically improves the efficacy of PD-1 blockade, suggesting that this combination therapy can be a rational anti-cancer combination immunotherapy.

Fibroblast activation protein-targeted near-infrared photoimmunotherapy depletes immunosuppressive cancer-associated fibroblasts and remodels local tumor immunity

BACKGROUND

Cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TME) play a critical role in tumor immunosuppression. However, targeted depletion of CAFs is difficult due to their diverse cells of origin and the resulting lack of specific surface markers. Near-infrared photoimmunotherapy (NIR-PIT) is a novel cancer treatment that leads to rapid cell membrane damage.

METHODS

In this study, we used anti-mouse fibroblast activation protein (FAP) antibody to target FAP+ CAFs (FAP-targeted NIR-PIT) and investigated whether this therapy could suppress tumor progression and improve tumor immunity.

RESULTS

FAP-targeted NIR-PIT induced specific cell death in CAFs without damaging adjacent normal cells. Furthermore, FAP-targeted NIR-PIT treated mice showed significant tumor regression in the CAF-rich tumor model accompanied by an increase in CD8+ tumor infiltrating lymphocytes (TILs). Moreover, treated tumors showed increased levels of IFN-γ, TNF-α, and IL-2 in CD8+ TILs compared with non-treated tumors, suggesting enhanced antitumor immunity.

CONCLUSIONS

Cancers with FAP-positive CAFs in their TME grow rapidly and FAP-targeted NIR-PIT not only suppresses their growth but improves tumor immunosuppression. Thus, FAP-targeted NIR-PIT is a potential therapeutic strategy for selectively targeting the TME of CAF+ tumors.

Nanomedicine for T-Cell Mediated Immunotherapy

T-cell immunotherapy offers outstanding advantages in the treatment of various diseases, and with the selection of appropriate targets, efficient disease treatment can be achieved. T-cell immunotherapy has made great progress, but clinical results show that only a small proportion of patients can benefit from T-cell immunotherapy. The extensive mechanistic work outlines a blueprint for using T cells as a new option for immunotherapy, but also presents new challenges, including the balance between different fractions of T cells, the inherent T-cell suppression patterns in the disease microenvironment, the acquired loss of targets, and the decline of T-cell viability. The diversity, flexibility, and intelligence of nanomedicines give them great potential for enhancing T-cell immunotherapy. Here, how T-cell immunotherapy strategies can be adapted with different nanomaterials to enhance therapeutic efficacy is discussed. For two different pathological states, immunosuppression and immune activation, recent advances in nanomedicines for T-cell immunotherapy in diseases such as cancers, rheumatoid arthritis, systemic lupus erythematosus, ulcerative colitis, and diabetes are summarized. With a focus on T-cell immunotherapy, this review highlights the outstanding advantages of nanomedicines in disease treatment, and helps advance one's understanding of the use of nanotechnology to enhance T-cell immunotherapy.

Engineered Nanomaterials for Tumor Immune Microenvironment Modulation in Cancer Immunotherapy

Tumor immunotherapy, represented by immune checkpoint blocking and chimeric antigen receptor (CAR) T cell therapy, has achieved promising results in clinical applications. However, it faces challenges that hinder its further development, such as limited response rates and poor tumor permeability. The efficiency of tumor immunotherapy is also closely linked to the structure and function of the immune microenvironment where the tumor resides. Recently, nanoparticle-based tumor immune microenvironment (TIME) modulation strategies have attracted a great deal of attention in cancer immunotherapy. This is primarily due to the distinctive physical characteristics of nanoparticles, which enable them to effectively infiltrate the TIME and selectively modulate its key constituents. This paper reviews recent advances in nanoparticle engineering to improve anti-cancer immunotherapy. Emerging nanoparticle-based approaches for modulating immune cells, tumor stroma, cytokines and immune checkpoints are discussed, aiming to overcome current challenges in the clinic. In addition, integrating immunotherapy with various treatment modalities such as chemotherapy and photodynamic therapy can be facilitated through the utilization of nanoparticles, thereby enhancing the efficacy of cancer treatment. The future challenges and opportunities of using nanomaterials to reeducate the suppressive immune microenvironment of tumors are also discussed, with the aim of anticipating further advancements in this growing field.

Translational research in head and neck cancer: Molecular and immunological updates

Head and neck squamous cell carcinoma (HNSCC) has a poor prognosis. Each year, approximately 880,000 patients are newly diagnosed with HNSCC worldwide, and 450,000 patients with HNSCC die. Risk factors for developing HNSCC have been identified, with cigarette smoking, alcohol consumption, and viral infections being the major factors. Owing to the prevalence of human papillomavirus infection, the number of HNSCC cases is increasing considerably. Surgery and chemoradiotherapy are the primary treatments for HNSCC. With advancements in tumor biology, patients are eligible for novel treatment modalities, namely targeted therapies, immunotherapy, and photoimmunotherapy. Because this area of research has rapidly progressed, clinicians should understand the basic biology of HNSCC to choose an appropriate therapy in the upcoming era of personalized medicine. This review summarized recent developments in tumor biology, focusing on epidemiology, genetic/epigenetic factors, the tumor microenvironment, microbiota, immunity, and photoimmunotherapy in HNSCC, as well as how these findings can be translated into clinical settings.

Near-infrared photoimmunotherapy targeting Nectin-4 in a preclinical model of bladder cancer

Enfortumab vedotin (EV), an antibody-drug conjugate (ADC) that targets Nectin-4, has shown promising results in the treatment of bladder cancer. However, multiple resistance mechanisms that are unique to ADCs limit the therapeutic potential of EV in clinical practice. Here, we developed and tested a Nectin-4-targeted near-infrared photoimmunotherapy (NIR-PIT) that utilizes the same target as EV but utilizes a distinct cytotoxic and immunotherapeutic pathway in preclinical models of bladder cancer. NIR-PIT was effective in vitro against luminal subtype human bladder cancer cell lines (RT4, RT112, MGH-U3, SW780, and HT1376-luc), but not against other subtype cell lines (UMUC3 and T24). In vivo, the tumor site was clearly visible by Nectin-4-IR700 fluorescence 24 h after its administration, suggesting the potential as an intraoperative imaging modality. NIR-PIT significantly suppressed tumor growth and prolonged survival in SW780 and RT112 xenograft models. Weekly treatment with NIR-PIT further improved tumor control in RT112 xenograft models. The effectiveness of NIR-PIT was also confirmed in HT1376-luc orthotopic xenograft models. Histological analysis verified that NIR-PIT induced a significant pathologic response. Taken together, Nectin-4-targeted NIR-PIT shows promise as a treatment for luminal subtype bladder cancers.

Targeting tumor-infiltrating tregs for improved antitumor responses

Immunotherapies have revolutionized the landscape of cancer treatment. Regulatory T cells (Tregs), as crucial components of the tumor immune environment, has great therapeutic potential. However, nonspecific inhibition of Tregs in therapies may not lead to enhanced antitumor responses, but could also trigger autoimmune reactions in patients, resulting in intolerable treatment side effects. Hence, the precision targeting and inhibition of tumor-infiltrating Tregs is of paramount importance. In this overview, we summarize the characteristics and subpopulations of Tregs within tumor microenvironment and their inhibitory mechanisms in antitumor responses. Furthermore, we discuss the current major strategies targeting regulatory T cells, weighing their advantages and limitations, and summarize representative clinical trials targeting Tregs in cancer treatment. We believe that developing therapies that specifically target and suppress tumor-infiltrating Tregs holds great promise for advancing immune-based therapies.

Near-infrared photoimmunotherapy and anti-cancer immunity

The activation of the anti-cancer immune system is an important strategy to control cancer. A new form of cancer phototherapy, near-infrared photoimmunotherapy (NIR-PIT), was approved for clinical use in 2020 and uses IRDye® 700DX (IR700)-conjugated antibodies and NIR light. After irradiation with NIR light, the antibody-IR700 conjugate forms water-insoluble aggregations on the plasma membrane of target cells. This aggregation causes lethal damage to the plasma membrane, and effectively leads to immunogenic cell death (ICD). Subsequently, ICD activates anti-cancer immune cells such as dendritic cells and cytotoxic T cells. Combination therapy with immune-checkpoint blockade has synergistically improved the anti-cancer effects of NIR-PIT. Additionally, NIR-PIT can eliminate immunosuppressive immune cells in light-irradiated tumors by using specific antibodies against regulatory T cells and myeloid-derived suppressor cells. In addition to cancer-cell-targeted NIR-PIT, such immune-cell-targeted NIR-PIT has shown promising results by activating the anti-cancer immune system. Furthermore, NIR-PIT can be used to manipulate the tumor microenvironment by eliminating only targeted cells in the tumor, and thus it also can be used to gain insight into immunity in basic research.

Tumor Suppression by Anti-Fibroblast Activation Protein Near-Infrared Photoimmunotherapy Targeting Cancer-Associated Fibroblasts

Cancer-associated fibroblasts (CAFs) constitute a prominent cellular component of the tumor stroma, with various pro-tumorigenic roles. Numerous attempts to target fibroblast activation protein (FAP), a highly expressed marker in immunosuppressive CAFs, have failed to demonstrate anti-tumor efficacy in human clinical trials. Near-infrared photoimmunotherapy (NIR-PIT) is a highly selective tumor therapy that utilizes an antibody-photo-absorbing conjugate activated by near-infrared light. In this study, we examined the therapeutic efficacy of CAF depletion by NIR-PIT in two mouse tumor models. Using CAF-rich syngeneic lung and spontaneous mammary tumors, NIR-PIT against FAP or podoplanin was performed. Anti-FAP NIR-PIT effectively depleted FAP+ CAFs, as well as FAP+ myeloid cells, and suppressed tumor growth, whereas anti-podoplanin NIR-PIT was ineffective. Interferon-gamma production by CD8 T and natural killer cells was induced within hours after anti-FAP NIR-PIT. Additionally, lung metastases were reduced in the treated spontaneous mammary cancer model. Depletion of FAP+ stromal as well as FAP+ myeloid cells effectively suppressed tumor growth in bone marrow chimeras, suggesting that the depletion of both cell types in one treatment is an effective therapeutic approach. These findings highlight a promising therapy for selectively eliminating immunosuppressive FAP+ cells within the tumor microenvironment.

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

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

FUNDING

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

Smart probes for optical imaging of T cells and screening of anti-cancer immunotherapies

T cells are an essential part of the immune system with crucial roles in adaptive response and the maintenance of tissue homeostasis. Depending on their microenvironment, T cells can be differentiated into multiple states with distinct functions. This myriad of cellular activities have prompted the development of numerous smart probes, ranging from small molecule fluorophores to nanoconstructs with variable molecular architectures and fluorescence emission mechanisms. In this Tutorial Review, we summarize recent efforts in the design, synthesis and application of smart probes for imaging T cells in tumors and inflammation sites by targeting metabolic and enzymatic biomarkers as well as specific surface receptors. Finally, we briefly review current strategies for how smart probes are employed to monitor the response of T cells to anti-cancer immunotherapies. We hope that this Review may help chemists, biologists and immunologists to design the next generation of molecular imaging probes for T cells and anti-cancer immunotherapies.

Aggregation-Induced Emission (AIE), Life and Health

Light has profoundly impacted modern medicine and healthcare, with numerous luminescent agents and imaging techniques currently being used to assess health and treat diseases. As an emerging concept in luminescence, aggregation-induced emission (AIE) has shown great potential in biological applications due to its advantages in terms of brightness, biocompatibility, photostability, and positive correlation with concentration. This review provides a comprehensive summary of AIE luminogens applied in imaging of biological structure and dynamic physiological processes, disease diagnosis and treatment, and detection and monitoring of specific analytes, followed by representative works. Discussions on critical issues and perspectives on future directions are also included. This review aims to stimulate the interest of researchers from different fields, including chemistry, biology, materials science, medicine, etc., thus promoting the development of AIE in the fields of life and health.

New insights and options into the mechanisms and effects of combined targeted therapy and immunotherapy in prostate cancer

Chronic inflammation is believed to drive prostate carcinogenesis by producing reactive oxygen species or reactive nitrogen species to induce DNA damage. This effect might subsequently cause epigenetic and genomic alterations, leading to malignant transformation. Although established therapeutic advances have extended overall survival, tumors in patients with advanced prostate cancer are prone to metastasis, transformation into metastatic castration-resistant prostate cancer, and therapeutic resistance. The tumor microenvironment (TME) of prostate cancer is involved in carcinogenesis, invasion and drug resistance. A plethora of preclinical studies have focused on immune-based therapies. Understanding the intricate TME system in prostate cancer may hold much promise for developing novel therapies, designing combinational therapeutic strategies, and further overcoming resistance to established treatments to improve the lives of prostate cancer patients. In this review, we discuss nonimmune components and various immune cells within the TME and their putative roles during prostate cancer initiation, progression, and metastasis. We also outline the updated fundamental research focusing on therapeutic advances of targeted therapy as well as combinational options for prostate cancer.

Polysaccharide-Based Stimulus-Responsive Nanomedicines for Combination Cancer Immunotherapy

Cancer immunotherapy is a promising antitumor approach, whereas nontherapeutic side effects, tumor microenvironment (TME) intricacy, and low tumor immunogenicity limit its therapeutic efficacy. In recent years, combination immunotherapy with other therapies has been proven to considerably increase antitumor efficacy. However, achieving codelivery of the drugs to the tumor site remains a major challenge. Stimulus-responsive nanodelivery systems show controlled drug delivery and precise drug release. Polysaccharides, a family of potential biomaterials, are widely used in the development of stimulus-responsive nanomedicines due to their unique physicochemical properties, biocompatibility, and modifiability. Here, the antitumor activity of polysaccharides and several combined immunotherapy strategies (e.g., immunotherapy combined with chemotherapy, photodynamic therapy, or photothermal therapy) are summarized. More importantly, the recent progress of polysaccharide-based stimulus-responsive nanomedicines for combination cancer immunotherapy is discussed, with the focus on construction of nanomedicine, targeted delivery, drug release, and enhanced antitumor effects. Finally, the limitations and application prospects of this new field are discussed.

Targeted Nanophotoimmunotherapy Potentiates Cancer Treatment by Enhancing Tumor Immunogenicity and Improving the Immunosuppressive Tumor Microenvironment

Cancer immunotherapy, such as immune checkpoint blockade, chimeric antigen receptor, and cytokine therapy, has emerged as a robust therapeutic strategy activating the host immune system to inhibit primary and metastatic lesions. However, low tumor immunogenicity (LTI) and immunosuppressive tumor microenvironment (ITM) severely compromise the killing effect of immune cells on tumor cells, which fail to evoke a strong and effective immune response. As an exogenous stimulation therapy, phototherapy can induce immunogenic cell death (ICD), enhancing the therapeutic effect of tumor immunotherapy. However, the lack of tumor targeting and the occurrence of immune escape significantly reduce its efficacy in vivo, thus limiting its clinical application. Nanophotoimmunotherapy (nano-PIT) is a precision-targeted tumor treatment that co-loaded phototherapeutic agents and various immunotherapeutic agents by specifically targeted nanoparticles (NPs) to improve the effectiveness of phototherapy, reduce its phototoxicity, enhance tumor immunogenicity, and reverse the ITM. This review will focus on the theme of nano-PIT, introduce the current research status of nano-PIT on converting "cold" tumors to "hot" tumors to improve immune efficacy according to the classification of immunotherapy targets, and discuss the challenges, opportunities, and prospects.

Bile salt hydrolase in non-enterotoxigenic Bacteroides potentiates colorectal cancer

Bile salt hydrolase (BSH) in Bacteroides is considered a potential drug target for obesity-related metabolic diseases, but its involvement in colon tumorigenesis has not been explored. BSH-expressing Bacteroides is found at high abundance in the stools of colorectal cancer (CRC) patients  with overweight and in the feces of a high-fat diet (HFD)-induced CRC mouse model. Colonization of B. fragilis 638R, a strain with low BSH activity, overexpressing a recombinant bsh gene from B. fragilis NCTC9343 strain, results in increased unconjugated bile acids in the colon and accelerated progression of CRC under HFD treatment. In the presence of high BSH activity, the resultant elevation of unconjugated deoxycholic acid and lithocholic acid activates the G-protein-coupled bile acid receptor, resulting in increased β-catenin-regulated chemokine (C-C motif) ligand 28 (CCL28) expression in colon tumors. Activation of the β-catenin/CCL28 axis leads to elevated intra-tumoral immunosuppressive CD25+FOXP3+ Treg cells. Blockade of the β-catenin/CCL28 axis releases the immunosuppression to enhance the intra-tumoral anti-tumor response, which decreases CRC progression under HFD treatment. Pharmacological inhibition of BSH reduces HFD-accelerated CRC progression, coincident with suppression of the β-catenin/CCL28 pathway. These findings provide insights into the pro-carcinogenetic role of Bacteroides in obesity-related CRC progression and characterize BSH as a potential target for CRC prevention and treatment.

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

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

Antibody Drug Conjugates of Near-Infrared Photoimmunotherapy (NIR-PIT) in Breast Cancers

Worldwide, the incidence rate of breast cancer is the highest in women. Approximately 2.3 million people were newly diagnosed and 0.685 million were dead of breast cancer in 2020, which continues to grow. Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype with a higher risk of recurrence and metastasis, but disappointly, there are no effective and specific therapies clinically, especially for patients presenting with metastatic diseases. Therefore, it is urgent to develop a new type of cancer therapy for survival improvisation and adverse effects alleviation of breast cancers. Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed, photochemistry-based cancer therapy. It was drive by an antibody-photoabsorber conjugate (APC) which is triggered by near-infrared light. The key part of APC is a cancer-targeting monoclonal antibody (mAb) that can bind to receptors or antigens on the surface of tumor cells. Because of this targeted conjugate accumulation, subsequent deployment of focal NIR-light results in functional damage on the targeted cell membranes without harming the immediately adjacent receptor-negative cells and evokes a kind of photochemical, speedy, and highly specific immunogenic cell death (ICD) of cancer cells with corresponding antigens. Subsequently, immature dendritic cells adjacent to dying cancer cells will become mature, further inducing a host-oriented anti-cancer immune response, complicatedly and comprehensively. Currently, NIR-PIT has progressed into phase 3 clinical trial for recurrent head and neck cancer. And preclinical studies have illustrated strong therapeutic efficacy of NIR-PIT targeting various molecular receptors overexpressed in breast cancer cells, including EGFR, HER2, CD44c, CD206, ICAM-1 and FAP-α. Thereby, NIR-PIT is in early trials, but appears to be a promising breast cancer therapy and moving into the future. Here, we present the specific advantages and discuss the most recent preclinical studies against several transmembrane proteins of NIR-PIT in breast cancers.

Mathematical models of the solid cancer induced by atomic bomb and the spontaneous cancer in the daily life-Proposal of a new medical treatment for cancers

BACKGROUND

A mathematical model of the radiation-induced cancer was devised to explain the change of incidence rates pursued by Radiation Effect Research Foundation for 25 years.

AIM

The aim of this work is construction of mechanisms of radiation-induced cancer and cancers observed in the daily life.

METHODS AND RESULTS

First, we found a way to separate spontaneous cancers from radiation-induced cancers observed among atomic-bomb victims in Hiroshima and Nagasaki districts by using a constructed algorithm. The isolated incidence rates of radiation-induced cancers were reproduced by a two-stage model mechanical collision of impinging radiation with cells and succeeding mutation of the damaged cell to cancer. This model satisfactorily reproduced observed solid cancer incidence rates. We further attempted to construct a mathematical model for the age-dependence of spontaneous cancers appearing in the daily life and concluded that the cancer should be generated at cell division.

CONCLUSION

With these findings, we reached to a conclusion that cancers may be suppressed by eliminating damaged cells with mild-dose radiation.

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.

Evaluating near-infrared photoimmunotherapy for targeting fibroblast activation protein-α expressing cells in vitro and in vivo

Photoimmunotherapy (PIT), carried out using an Ab conjugated to the near infrared dye IRDye700DX, is achieving significant success in target-specific elimination of cells. Fibroblast activation protein alpha (FAP-α) is an important target in cancer because of its expression by cancer-associated fibroblasts (CAFs) as well as by some cancer cells. Cancer-associated fibroblasts that express FAP-α have protumorigenic and immune suppressive functions. Using immunohistochemistry of human breast cancer tissue microarrays, we identified an increase of FAP-α⁺  CAFs in invasive breast cancer tissue compared to adjacent normal tissue. We found FAP-α expression increased in fibroblasts cocultured with cancer cells. In proof-of-principle studies, we engineered human FAP-α overexpressing MDA-MB-231 and HT-1080 cancer cells and murine FAP-α overexpressing NIH-3T3 fibroblasts to evaluate several anti-FAP-α Abs and selected AF3715 based on its high binding affinity with both human and mouse FAP-α. After conjugation of AF3715 with the phthalocyanine dye IR700, the resultant Ab conjugate, FAP-α-IR700, was evaluated in cells and tumors for its specificity and effectiveness in eliminating FAP-α expressing cell populations with PIT. Fibroblast activation protein-α-IR700-PIT resulted in effective FAP-α-specific cell killing in the engineered cancer cells and in two patient-derived CAFs in a dose-dependent manner. Following an intravenous injection, FAP-α-IR700 retention was three-fold higher than IgG-IR700 in FAP-α overexpressing tumors, and two-fold higher compared to WT tumors. Fibroblast activation protein-α-IR700-PIT resulted in significant growth inhibition of tumors derived from FAP-α overexpressing human cancer cells. A reduction of endogenous FAP-α⁺  murine CAFs was identified at 7 days after FAP-α-IR700-PIT. Fibroblast activation protein-α-targeted near infrared PIT presents a promising strategy to eliminate FAP-α⁺  CAFs.

Systemic enhancement of antitumour immunity by peritumourally implanted immunomodulatory macroporous scaffolds

A tumour microenvironment abundant in regulatory T (Treg) cells aids solid tumours to evade clearance by effector T cells. Systemic strategies to suppress Treg cells or to augment immunity can elicit autoimmune side effects, cytokine storms and other toxicities. Here we report the design, fabrication and therapeutic performance of a biodegradable macroporous scaffold, implanted peritumourally, that releases a small-molecule inhibitor of transforming growth factor β to suppress Treg cells, chemokines to attract effector T cells and antibodies to stimulate them. In two mouse models of aggressive tumours, the implant boosted the recruitment and activation of effector T cells into the tumour and depleted it of Treg cells, which resulted in an 'immunological abscopal effect' on distant metastases and in the establishment of long-term memory that impeded tumour recurrence. We also show that the scaffold can be used to deliver tumour-antigen-specific T cells into the tumour. Peritumourally implanted immunomodulatory scaffolds may represent a general strategy to enhance T-cell immunity and avoid the toxicities of systemic therapies.

Trametinib improves Treg selectivity of anti-CCR4 antibody by regulating CCR4 expression in CTLs in oral squamous cell carcinoma

Regulatory T-cells (Tregs) play a major role in suppressing anti-tumor immune responses. Mogamulizumab, an anti-CC chemokine receptor type 4 (CCR4) monoclonal antibody, depletes effector Tregs (eTregs). However, the clinical efficacy of mogamulizumab was limited in phase Ia/Ib studies for solid tumors (NCT01929486); the finding suggests that mogamulizumab may also deplete beneficial CCR4⁺CD8⁺ T-cells in patients. Therefore, we focused on CTLs and aimed to identify a way to protect CCR4⁺ CTLs. Here, we evaluated the association of CCR4 expression in cytotoxic T-lymphocytes (CTLs) with antigen and cytokine stimulations and kinase inhibition using cytomegalovirus antigen instead of tumor antigen. CCR4 expression in CTLs was induced by antigen stimulation (mean 3.14-29.0%), enhanced by transforming growth factor-β1 (TGF-β1) (mean 29.0-51.2%), and downregulated by trametinib with (mean 51.2-11.4%) or without TGF-β1 treatment (mean 29.0-6.98%). Phosphorylation of ERK in CD8⁺ T-cells was suppressed by trametinib. Regarding the effect on immunological function of CTL, trametinib reduced cytokine production but not affected cytotoxicity. Importantly, trametinib alleviated CTL reduction by anti-CCR4 antibody without affecting eTreg depletion because CCR4 expression in eTregs was not downregulated. In conclusion, combination therapy with trametinib may improve the clinical efficacy of mogamulizumab.

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.

Characteristics of tumor microenvironment and novel immunotherapeutic strategies for non-small cell lung cancer

Immune checkpoint inhibitor-based immunotherapy has revolutionized the treatment approach of non-small cell lung cancer (NSCLC). Monoclonal antibodies against programmed cell death-1 (PD-1) and PD-ligand 1 (PD-L1) are widely used in clinical practice, but other antibodies that can circumvent innate and acquired resistance are bound to undergo preclinical and clinical studies. However, tumor cells can develop and facilitate the tolerogenic nature of the tumor microenvironment (TME), resulting in tumor progression. Therefore, the immune escape mechanisms exploited by growing lung cancer involve a fine interplay between all actors in the TME. A better understanding of the molecular biology of lung cancer and the cellular/molecular mechanisms involved in the crosstalk between lung cancer cells and immune cells in the TME could identify novel therapeutic weapons in the old war against lung cancer. This article discusses the role of TME in the progression of lung cancer and pinpoints possible advances and challenges of immunotherapy for NSCLC.

Selective depletion of polymorphonuclear myeloid derived suppressor cells in tumor beds with near infrared photoimmunotherapy enhances host immune response

The immune system is recognized as an important factor in regulating the development, progression, and metastasis of cancer. Myeloid-derived suppressor cells (MDSCs) are a major immune-suppressive cell type by interfering with T cell activation, promoting effector T cell apoptosis, and inducing regulatory T cell expansion. Consequently, reducing or eliminating MDSCs has become a goal of some systemic immunotherapies. However, by systemically reducing MDSCs, unwanted side effects can occur. Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed treatment that selectively kills targeted cells without damaging adjacent normal cells. The aim of this study is to evaluate the antitumor efficacy of MDSC-directed NIR-PIT utilizing anti-Ly6G antibodies to specifically destroy polymorphonuclear (PMN)-MDSCs in the tumor microenvironment (TME) in syngeneic mouse models. PMN-MDSCs were selectively eliminated within tumors by Ly6G-targeted NIR-PIT. There was significant tumor growth suppression and prolonged survival in three treated tumor models. In the early phase after NIR-PIT, dendritic cell maturation/activation and CD8⁺ T cell activation were enhanced in both intratumoral tissues and tumor-draining lymph nodes, and NK cells demonstrated increased expression of cytotoxic molecules. Host immunity remained activated in the TME for at least one week after NIR-PIT. Abscopal effects in bilateral tumor models were observed. Furthermore, the combination of NIR-PIT targeting cancer cells and PMN-MDSCs yielded synergistic effects and demonstrated highly activated host tumor immunity. In conclusion, we demonstrated that selective local PMN-MDSCs depletion by NIR-PIT could be a promising new cancer immunotherapy.

Dual-targeted near-infrared photoimmunotherapy for esophageal cancer and cancer-associated fibroblasts in the tumor microenvironment

Cancer-associated fibroblasts (CAFs) play a significant role in tumor progression within the tumor microenvironment. Previously, we used near-infrared photoimmunotherapy (NIR-PIT), a next-generation cancer cell-targeted phototherapy, to establish CAF-targeted NIR-PIT. In this study, we investigated whether dual-targeted NIR-PIT, targeting cancer cells and CAFs, could be a therapeutic strategy. A total of 132 cases of esophageal cancer were analyzed for epidermal growth factor receptor (EGFR), human epidermal growth factor 2 (HER2), and fibroblast activation protein (FAP) expression using immunohistochemistry. Human esophageal cancer cells and CAFs were co-cultured and treated with single- or dual-targeted NIR-PIT in vitro. These cells were co-inoculated into BALB/c-nu/nu mice and the tumors were treated with single-targeted NIR-PIT or dual-targeted NIR-PIT in vivo. Survival analysis showed FAP- or EGFR-high patients had worse survival than patients with low expression of FAP or EGFR (log-rank, P < 0.001 and P = 0.074, respectively), while no difference was observed in HER2 status. In vitro, dual (EGFR/FAP)-targeted NIR-PIT induced specific therapeutic effects in cancer cells and CAFs along with suppressing tumor growth in vivo, whereas single-targeted NIR-PIT did not show any significance. Moreover, these experiments demonstrated that dual-targeted NIR-PIT could treat cancer cells and CAFs simultaneously with a single NIR light irradiation. We demonstrated the relationship between EGFR/FAP expression and prognosis of patients with esophageal cancer and the stronger therapeutic effect of dual-targeted NIR-PIT than single-targeted NIR-PIT in experimental models. Thus, dual-targeted NIR-PIT might be a promising therapeutic strategy for cancer treatment.

Near-Infrared Photoimmunotherapy for Oropharyngeal Cancer

Human papillomavirus (HPV)-associated oropharyngeal cancer has a better prognosis than other head and neck cancers. However, rates of recurrence and metastasis are similar and the prognosis of recurrent or metastatic HPV-associated oropharyngeal cancer is poor. Near-infrared photoimmunotherapy (NIR-PIT) is a treatment involving administration of a photosensitizer (IRDye^®700DX) conjugated to a monoclonal antibody followed by activation with near-infrared light illumination. It is a highly tumor-specific therapy with minimal toxicity in normal tissues. Moreover, NIR-PIT is expected to have not only direct effects on a treated lesion but also immune responses on untreated distant lesions. NIR-PIT with cetuximab-IR700 (AlluminoxTM) has been in routine clinical use since January 2021 for unresectable locally advanced or locally recurrent head and neck cancer in patients that have previously undergone radiotherapy in Japan. NIR-PIT for head and neck cancer (HN-PIT) is expected to provide a curative treatment option for the locoregional recurrent or metastatic disease after radiotherapy and surgery. This article reviews the mechanism underlying the effect of NIR-PIT and recent clinical trials of NIR-PIT for head and neck cancers, treatment-specific adverse events, combination treatment with immune checkpoint inhibitors, illumination approach and posttreatment quality of life, and provides a case of series of two patients who receive NIR-PIT for oropharyngeal cancer at our institution.

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.

Promoted CD4+ T cell-derived IFN-γ/IL-10 by photobiomodulation therapy modulates neurogenesis to ameliorate cognitive deficits in APP/PS1 and 3xTg-AD mice

Background

The immune system has been implicated in synaptic plasticity, inflammation, and the progression of Alzheimer's disease (AD). However, there were few studies on improving the niche microenvironment of neural stem cells (NSCs) in the brain of AD to promote adult hippocampal neurogenesis (AHN) by regulating the function of non-parenchymal immune cells.

Methods

The lymph nodes of amyloid precursor protein/presenilin 1 (APP/PS1) and 3xTg (APP/PS1/tau) mouse models of AD were treated with photobiomodulation therapy (PBMT) for 10 J/cm² per day for 1 month (10 min for each day), T lymphocytes isolated from these two AD models were treated with PBMT for 2 J/cm² (5 min for each time). The NSCs isolated from hippocampus of these two AD models at E14, and the cells were co-cultivated with PBMT-treated T lymphocyte conditioned medium for NSCs differentiation.

Results

Our results showed that PBMT treatment could promote AHN and reverse cognitive deficits in AD mouse model. The expression of interferon-γ (IFN-γ) and interleukin-10 (IL-10) was upregulated in the brain of these two AD models after PBMT treated, which was induced by the activation of Janus kinase 2 (JAK2)-mediated signal transducer and activator of transcription 4 (STAT4)/STAT5 signaling pathway in CD4⁺ T cells. In addition, elevated CD4⁺ T cell levels and upregulated transforming growth factor-β1 (TGFβ1)/insulin-like growth factors-1 (IGF-1)/brain-derived neurotrophic factor (BDNF) protein expression levels were also detected in the brain. More importantly, co-cultivated the PBMT-treated T lymphocyte conditioned medium with NSCs derived from these two AD models was shown to promote NSCs differentiation, which was reflected in the upregulation of both neuronal class-III β-tubulin (Tuj1) and postsynaptic density protein 95 (PSD95), but the effects of PBMT was blocked by reactive oxygen species (ROS) scavenger or JAK2 inhibitor.

Conclusion

Our research suggests that PBMT exerts a beneficial neurogenesis modulatory effect through activating the JAK2/STAT4/STAT5 signaling pathway to promote the expression of IFN-γ/IL-10 in non-parenchymal CD4⁺ T cells, induction of improvement of brain microenvironmental conditions and alleviation of cognitive deficits in APP/PS1 and 3xTg-AD mouse models.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02617-5.

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.

Phototheranostics for multifunctional treatment of cancer with fluorescence imaging

Phototheranostics stem from the recent advances in nanomedicines and bioimaging to diagnose and treat human diseases. Since tumors' diversity, heterogeneity, and instability limit the clinical application of traditional diagnostics and therapeutics, phototheranostics, which combine light-induced therapeutic and diagnostic modalities in a single platform, have been widely investigated. Numerous efforts have been made to develop phototheranostics for efficient light-induced antitumor therapeutics with minimal side effects. Herein, we review the fundamentals of phototheranostic nanomedicines with their biomedical applications. Furthermore, the progress of near-infrared fluorescence imaging and cancer treatments, including photodynamic therapy and photothermal therapy, along with chemotherapy, immunotherapy, and gene therapy, are summarized. This review also discusses the opportunities and challenges associated with the clinical translation of phototheranostics in pan-cancer research. Phototheranostics can pave the way for future research, improve the quality of life, and prolong cancer patients' survival times.

The soldiers needed to be awakened: Tumor-infiltrating immune cells

In the tumor microenvironment, tumor-infiltrating immune cells (TIICs) are a key component. Different types of TIICs play distinct roles. CD8+ T cells and natural killer (NK) cells could secrete soluble factors to hinder tumor cell growth, whereas regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) release inhibitory factors to promote tumor growth and progression. In the meantime, a growing body of evidence illustrates that the balance between pro- and anti-tumor responses of TIICs is associated with the prognosis in the tumor microenvironment. Therefore, in order to boost anti-tumor response and improve the clinical outcome of tumor patients, a variety of anti-tumor strategies for targeting TIICs based on their respective functions have been developed and obtained good treatment benefits, including mainly immune checkpoint blockade (ICB), adoptive cell therapies (ACT), chimeric antigen receptor (CAR) T cells, and various monoclonal antibodies. In recent years, the tumor-specific features of immune cells are further investigated by various methods, such as using single-cell RNA sequencing (scRNA-seq), and the results indicate that these cells have diverse phenotypes in different types of tumors and emerge inconsistent therapeutic responses. Hence, we concluded the recent advances in tumor-infiltrating immune cells, including functions, prognostic values, and various immunotherapy strategies for each immune cell in different tumors.

Tipping the scales: Immunotherapeutic strategies that disrupt immunosuppression and promote immune activation

Immunotherapy has emerged as an effective therapeutic approach for several cancer types. However, only a subset of patients exhibits a durable response due in part to immunosuppressive mechanisms that allow tumor cells to evade destruction by immune cells. One of the hallmarks of immune suppression is the paucity of tumor-infiltrating lymphocytes (TILs), characterized by low numbers of effector CD4+ and CD8+ T cells in the tumor microenvironment (TME). Additionally, the proper activation and function of lymphocytes that successfully infiltrate the tumor are hampered by the lack of co-stimulatory molecules and the increase in inhibitory factors. These contribute to the imbalance of effector functions by natural killer (NK) and T cells and the immunosuppressive functions by myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs) in the TME, resulting in a dysfunctional anti-tumor immune response. Therefore, therapeutic regimens that elicit immune responses and reverse immune dysfunction are required to counter immune suppression in the TME and allow for the re-establishment of proper immune surveillance. Immuno-oncology (IO) agents, such as immune checkpoint blockade and TGF-β trapping molecules, have been developed to decrease or block suppressive factors to enable the activity of effector cells in the TME. Therapeutic agents that target immunosuppressive cells, either by direct lysis or altering their functions, have also been demonstrated to decrease the barrier to effective immune response. Other therapies, such as tumor antigen-specific vaccines and immunocytokines, have been shown to activate and improve the recruitment of CD4+ and CD8+ T cells to the tumor, resulting in improved T effector to Treg ratio. The preclinical data on these diverse IO agents have led to the development of ongoing phase I and II clinical trials. This review aims to provide an overview of select therapeutic strategies that tip the balance from immunosuppression to immune activity in the TME.

Near-infrared-induced drug release from antibody-drug double conjugates exerts a cytotoxic photo-bystander effect

Ideal cancer treatments specifically target and eradicate tumor cells without affecting healthy cells. Therefore, antibody-based therapies that specifically target cancer antigens can be considered ideal cancer therapies. Antibodies linked with small-molecule drugs (i.e., antibody-drug conjugates [ADCs]) are widely used in clinics as antibody-based therapeutics. However, because tumors express antigens heterogeneously, greater target specificity and stable binding of noncleavable linkers in ADCs limit their antitumor effects. To overcome this problem, strategies, including decreasing the binding strength, conjugating more drugs, and targeting tumor stroma, have been applied, albeit with limited success. Thus, further technological advancements are required to remotely control the ADCs. Here, we described a drug that is photo-releasable from an ADC created via simple double conjugation and its antitumor effects both on target and nontarget tumor cells. Specifically, noncleavable T-DM1 was conjugated with IR700DX to produce T-DM1-IR700. Although T-DM1-IR700 itself is noncleavable, with NIR-light irradiation, it can release DM1-derivatives which elicited antitumor effect in vitro mixed culture and in vivo mixed tumor model which are mimicking heterogeneous tumor-antigen expression same as real clinical tumors. This cytotoxic photo-bystander effect occurred in various types mixed cultures in vitro, and changing antibodies also exerted photo-bystander effects, suggesting that this technology can be used for targeting various specific cancer antigens. These findings can potentially aid the development of strategies to address challenges associated with tumor expression of heterogeneous antigen.

Breaking photoswitch activation depth limit using ionising radiation stimuli adapted to clinical application

Electromagnetic radiation-triggered therapeutic effect has attracted a great interest over the last 50 years. However, translation to clinical applications of photoactive molecular systems developed to date is dramatically limited, mainly because their activation requires excitation by low-energy photons from the ultraviolet to near infra-red range, preventing any activation deeper than few millimetres under the skin. Herein we conceive a strategy for photosensitive-system activation potentially adapted to biological tissues without any restriction in depth. High-energy stimuli, such as those employed for radiotherapy, are used to carry energy while molecular activation is provided by local energy conversion. This concept is applied to azobenzene, one of the most established photoswitches, to build a radioswitch. The radiation-responsive molecular system developed is used to trigger cytotoxic effect on cancer cells upon gamma-ray irradiation. This breakthrough activation concept is expected to expand the scope of applications of photosensitive systems and paves the way towards the development of original therapeutic approaches.

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.

Emerging drug targets for triple-negative breast cancer: A guided tour of the preclinical landscape

INTRODUCTION

Triple-negative breast cancer (TNBC) is the most fatal molecular subtype of breast cancer because of its aggressiveness and resistance to chemotherapy. FDA-approved therapies for TNBC are limited to poly(ADP-ribose) polymerase inhibitors, immune checkpoint inhibitors, and trophoblast cell surface antigen 2-targeted antibody-drug conjugate. Therefore, developing a novel effective targeted therapy for TNBC is an urgent unmet need.

AREAS COVERED

In this narrative review, we discuss emerging targets for TNBC treatment discovered in early translational studies. We focus on cancer cell membrane molecules, hyperactive intracellular signaling pathways, and the tumor microenvironment (TME) based on their druggability, therapeutic potency, specificity to TNBC, and application in immunotherapy.

EXPERT OPINION

The significant challenges in the identification and validation of TNBC-associated targets are 1) application of appropriate genetic, molecular, and immunological approaches for modulating the target, 2) establishment of a proper mouse model that accurately represents the human immune TME, 3) TNBC molecular heterogeneity, and 4) failure translation of preclinical findings to clinical practice. To overcome those difficulties, future research needs to apply novel technology, such as single-cell RNA sequencing, thermostable group II intron reverse transcriptase sequencing, and humanized mouse models. Further, combination treatment targeting multiple pathways in both the TNBC tumor and its TME is essential for effective disease control.

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.