Near-infrared photoimmunotherapy for osteosarcoma targeting epidermal growth factor receptor.

Osteosarcoma is the most common bone tumor, and it possesses high metastatic propensity. Although systemic chemotherapy has improved its prognosis, improvements in survival rates have stalled in recent years. Moreover, the prognosis of patients with metastatic osteosarcoma remains poor. Near-infrared photoimmunotherapy (NIR-PIT) is a highly selective cancer therapy that induces immunogenic cell death (ICD), and the therapeutic effects spread to distant metastatic sites. Therefore, NIR-PIT could be useful in both primary and metastatic osteosarcoma treatment. In this study, we investigated the efficacy of NIR-PIT targeting epidermal growth factor receptor (EGFR) in osteosarcoma. The cytotoxic effects of NIR-PIT in osteosarcoma cell lines with different EGFR expression levels (MG63; high, Saos-2; low) were evaluated. NIR-PIT-induced cell death was dependent on the EGFR expression level. After NIR-PIT, swelling and bleb formation, the characteristic morphological changes induced by NIR-PIT associated with necrosis caused by the influx of extracellular fluid, were observed. In addition, the release of the ICD markers lactate dehydrogenase and ATP was detected after NIT-PIT. NIR-PIT significantly suppressed tumor growth in tumor-bearing mice. This study revealed that NIR-PIT targeting EGFR has therapeutic effects and induces ICD in osteosarcoma; thus, it is potentially a novel therapeutic strategy for primary and metastatic osteosarcoma.

Photo-Amplified Plasma Membrane Rupture by Membrane-Anchoring NIR-II Small Molecule Design for Improved Cancer Photoimmunotherapy.

Immunotherapy is a promising cancer treatment method for eradicating tumor cells by enhancing the immune response. However, there are several major obstacles to conventional phototherapy-mediated immune responses, including inadequate immunogenicity and immunosuppressive environment. Here, we present a novel photoimmunotherapy modality-the development of membrane-anchoring small molecule inducing plasma membrane rupture (PMR) by NIR-II photo-stimulation, thus evoking cell necrotic death and enhancing antitumor immunotherapy. Our top-performing membrane-anchoring small molecule (CBT-3) exhibits temperature-tunable PMR efficiency, allowing rapid necrotic death in cancer cells at 50 µM dose by using exogenous NIR-II light-mediated mild photothermal effect (1064 nm, 0.6 W cm-2). Further evidence indicated that this gentle therapeutic approach activated inflammatory signaling pathways in cells, enhanced immunogenic cell death, and reshaped the immunosuppressive tumor microenvironment, ultimately promoting systemic antitumor immune responses in vivo. This study represents the first instance of utilizing NIR-II photo-amplified PMR effect based on membrane-anchoring small molecule, providing a novel avenue for advancing cancer photoimmunotherapy.

Dual-Activatable Nano-Immunomodulator for NIR-II Fluorescence Imaging-Guided Precision Cancer Photodynamic Immunotherapy.

Photodynamic immunotherapy which combines photodynamic therapy with immunotherapy has become an important and effective method for the treatment of cancer. However, most cancer photodynamic immunotherapeutic systems are not able to achieve precise release of immunomodulators, resulting in systemic side effects and poor patient outcomes. Herein, a dual-activatable nano-immunomodulator (DIR NP), which both its photodynamic effect and agonist release can be activated under specific stimuli, is reported for precision cancer photodynamic immunotherapy. The DIR NP is self-assembled from an R848-conjugated amphiphilic polymer (mPEG-TK-R848) and a hydrophobic oxidized bovine serum albumin (BSA-SOH)-conjugatable photosensitizer (DIR). DIR NPs may generate a small amount of 1O2 under 808 nm laser irradiation, leading to the cleavage of thioketal (TK) moiety and release of R848 and DIR. The released DIR may conjugate with tumor-overexpressed BSA-SOH, improving its photodynamic efficiency and NIR-II fluorescence signal. Such photodynamic efficiency improvement may further enhance the release of cargoes upon irradiation. The activated photodynamic effect induces immunogenic cell death (ICD) to release immune factors and R848 can enhance the maturation of dendritic cells for inhibiting the growth of both primary and distant tumors and eliminating lung metastasis. Therefore, this study provides a dual-activatable intelligent nano-immunomodulator for precise regulation of tumor photodynamic immunotherapy.

Cell membrane-camouflaged nanoarchitectonics of photosensitizer nanoparticles for enhanced phototherapy in surgery.

Surgical risk and wound area can be reduced by diminishing tumor volume before surgery. The chemotherapy and radiotherapy currently used that can reduce the tumor volume generally cause severe systemic side effects. Phototherapy has recently emerged as an effective treatment modality for superficial cancers. However, phototherapy is limited by the low utilization of photosensitizer, the tumor hypoxia, and the low photothermal conversion efficiency. Herein, we report the cancer membrane biomimetic nanoparticles assembled by Chlorin e6 (Ce6) and chlorambucil (CRB). Ce6@CRB nanoparticles (CCNPs) show excellent photothermal conversion efficiency, which is 2 times higher than free Ce6. Meanwhile, CCNPs can produce singlet oxygen stably compared to free Ce6 thereby reducing the dependence on oxygen. Furthermore, the coating of 4 T1 cancer membrane on the surface of CCNPs endows them with the ability of homologous targeting, not only improving the utilization of Ce6, but also effectively activating the immune system in vivo when combined photodynamic therapy (PDT) and photothermal therapy (PTT). Intriguingly, surgical resection is performed after phototherapy in this treatment regimen, which can effectively reduce the wound area. Together, this work provided a feasible and creative method for tumor clinical therapy for its patient-centric and humanitarian focus.

Multi-Functional AIE Phototheranostic Agent Enhancing αPD-L1 Response for Oral Squamous Cell Carcinoma Immunotherapy.

Oral squamous cell carcinoma (OSCC) represents a prevalent head and neck malignancy with surgical intervention as the primary clinical option. Immunotherapy, particularly immune checkpoint blockade (ICB) targeting PD-1/PD-L1 shows great promise but is impeded by the immunosuppressive tumor microenvironment and low PD-L1 expression in OSCC. Herein, the "all-in-one" phototherapeutic nanoparticles (TSD NPs) are reported with balanced reactive oxygen species and photothermal conversion capacity for combined photoimmunotherapy and ICB immunotherapy against OSCC. A novel electron acceptor, 3-(dicyanomethylene)-2,3-dihydrobenzothiophene-1,1-dioxide (DTM), is introduced to develop the phototherapeutic agent with aggregation-induced emission (AIE) feature and NIR-II fluorescence centered at 1000 nm. Benefiting from the AIE feature and the DTM acceptor, the resultant TSD NPs also exhibit strong type I reactive oxygen species (ROS) generation and high photothermal conversion efficiency (45.3%), which can profoundly induce immunogenic cell death (ICD), activate cytotoxic T lymphocytes, and convert the immunosuppressive tumor microenvironment into an immune-supportive one. Additionally, TSD NPs upregulate the PD-L1 expression on OSCC cells, thus enhancing the efficacy of combined treatment with αPD-L1 ICB immunotherapy. This results show that the synergistic treatment of TSD NPs and αPD-L1 effectively eradicates solid OSCC tumors without adverse effects on normal tissues, proving a novel and promising strategy for OSCC management.

Real-Time Fluorescence Monitoring System for Optimal Light Dosage in Cancer Photoimmunotherapy.

Background/Objectives: Near-infrared photoimmunotherapy (NIR-PIT) was recently approved for the treatment of unresectable locally advanced or recurrent head and neck cancers in Japan; however, only one clinical dose has been validated in clinical trials, potentially resulting in excessive or insufficient dosing. Moreover, IRDye700X (IR700) fluorescence intensity plateaus during treatment, indicating a particular threshold for the antitumor effects. Therefore, we investigated the NIR laser dose across varying tumor sizes and irradiation methods until the antitumor effects of the fluorescence decay rate plateaued. Methods: Mice were subcutaneously transplanted with A431 xenografts and categorized into control, clinical dose (cylindrical irradiation at 100 J/cm², frontal irradiation at 50 J/cm²), and evaluation groups. The rate of tumor IR700 fluorescence intensity decay to reach predefined rates (-0.05%/s or -0.2%/s) until the cessation of light irradiation was calculated using a real-time fluorescence imaging system. Results: The evaluation group exhibited antitumor effects comparable to those of the clinical dose group at a low irradiation dose. Similar results were observed across tumor sizes and irradiation methods. Conclusions: In conclusion, the optimal antitumor effect of NIR-PIT is achieved when the fluorescence decay rate reaches a plateau, indicating the potential to determine the appropriate dose for PIT using a real-time fluorescence monitoring system.

A relay-type innate immunity activation strategy involving water-soluble NIR-II AIEgen for boosted tumor photo-immunotherapy.

Background: Effective innate immunity activation could dramatically improve the anti-tumor efficacy and increase the beneficiary population of immunotherapy. However, the anti-tumor effect of unimodal immunotherapy is still not satisfactory. Methods: Herein, a novel relay-type innate immunity activation strategy based on photo-immunotherapy mediated by a water-soluble aggregation-induced emission luminogen, PEG420-TQ, with the assistant of toll-like receptor 7 (TLR-7) agonist, imiquimod (R837), was developed and constructed. Results: The strategy could promote tumor cells to undergo immunogenic cell death (ICD) induced by the well-designed PEG420-TQ@R837 (PTQ@R) nanoplatform under light irradiation, which in turn enhanced the infiltration of immune cells and the activation of innate immune cells to achieve the first innate immunity activation. The second innate immunity activation was subsequently achieved by drug delivery of R837 via apoptotic bodies (ApoBDs), further enhancing the anti-tumor activity of infiltrated immune cells. Conclusion: The strategy ultimately demonstrated robust innate immunity activation and achieved excellent performance against tumor growth and metastasis. The construction of the relay-type innate immunity activation strategy could provide a new idea for the application of immunotherapy in clinical trials.

A new silicon phthalocyanine dye induces pyroptosis in prostate cancer cells during photoimmunotherapy.

Photoimmunotherapy (PIT) combines the specificity of antibodies with the cytotoxicity of light activatable photosensitizers (PS) and is a promising new cancer therapy. We designed and synthesized, in a highly convergent manner, the silicon phthalocyanine dye WB692-CB2, which is novel for being the first light-activatable PS that can be directly conjugated via a maleimide linker to cysteines. In the present study we conjugated WB692-CB2 to a humanized antibody with engineered cysteines in the heavy chains that specifically targets the prostate-specific membrane antigen (PSMA). The resulting antibody dye conjugate revealed high affinity and specificity towards PSMA-expressing prostate cancer cells and induced cell death after irradiation with red light. Treated cells exhibited morphological characteristics associated with pyroptosis. Mechanistic studies revealed the generation of reactive oxygen species, triggering a cascade of intracellular events involving lipid peroxidation, caspase-1 activation, gasdermin D cleavage and membrane rupture followed by release of pro-inflammatory cellular contents. In first in vivo experiments, PIT with our antibody dye conjugate led to a significant reduction of tumor growth and enhanced overall survival in mice bearing subcutaneous prostate tumor xenografts. Our study highlights the future potential of the new phthalocyanine dye WB692-CB2 as PS for the fluorescence-based detection and PIT of cancer, including local prostate tumor lesions, and systemic activation of anti-tumor immune responses by the induction of pyroptosis.

Mild near-infrared laser-triggered photo-immunotherapy potentiates immune checkpoint blockade via an all-in-one theranostic nanoplatform.

One of the primary challenges for immune checkpoint blockade (ICB)-based therapy is the limited infiltration of T lymphocytes (T cells) into tumors, often referred to as immunologically "cold" tumors. A promising strategy to enhance the anti-tumor efficacy of ICB is to increase antigen exposure, thereby enhancing T cell activation and converting "cold" tumors into "hot" ones. Herein, we present an innovative all-in-one therapeutic nanoplatform to realize local mild photothermal- and photodynamic-triggered antigen exposure, thereby improving the anti-tumor efficacy of ICB. This nanoplatform involves conjugating programmed death-ligand 1 antibody (aPD-L1) with gadolinium-doped near-infrared (NIR)-emitting carbon dots (aPD-L1@GdCDs), which displays negligible cytotoxicity in the absence of light. But under controlled NIR laser irradiation, the GdCDs produce combined photothermal and photodynamic effects. This not only results in tumor ablation but also induces immunogenic cell death (ICD), facilitating enhanced infiltration of CD8+ T cells in the tumor area. Importantly, the combination of aPD-L1 with photothermal and photodynamic therapies via aPD-L1@GdCDs significantly boosts CD8+ T cell infiltration, reduces tumor size, and improves anti-metastasis effects compared to either GdCDs-based phototherapy or aPD-L1 alone. In addition, the whole treatment process can be monitored by multi-modal fluorescence/photoacoustic/magnetic resonance imaging (FLI/PAI/MRI). Our study highlights a promising nanoplatform for cancer diagnosis and therapy, as well as paves the way to promote the efficacy of ICB therapy through mild photothermal- and photodynamic-triggered immunotherapy.

An Acceptor-Donor-Acceptor Structured Nano-Aggregate for NIR-Triggered Interventional Photoimmunotherapy of Cervical Cancer.

Compared with conventional therapies, photoimmunotherapy offers precise targeted cancer treatment with minimal damage to healthy tissues and reduced side effects, but its efficacy may be limited by shallow light penetration and the potential for tumor resistance. Here, an acceptor-donor-acceptor (A-D-A)-structured nanoaggregate is developed with dual phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), triggered by single near-infrared (NIR) light. Benefiting from strong intramolecular charge transfer (ICT), the A-D-A-structured nanoaggregates exhibit broad absorption extending to the NIR region and effectively suppressed fluorescence, which enables deep penetration and efficient photothermal conversion (η = 67.94%). A suitable HOMO-LUMO distribution facilitates sufficient intersystem crossing (ISC) to convert ground-state oxygen (3O2) to singlet oxygen (1O2) and superoxide anions (·O2 -), and catalyze hydroxyl radical (·OH) generation. The enhanced ICT and ISC effects endow the A-D-A structured nanoaggregates with efficient PTT and PDT for cervical cancer, inducing efficient immunogenic cell death. In combination with clinical aluminum adjuvant gel, a novel photoimmunotherapy strategy for cervical cancer is developed and demonstrated to significantly inhibit primary and metastatic tumors in orthotopic and intraperitoneal metastasis cervical cancer animal models. The noninvasive therapy strategy offers new insights for clinical early-stage and advanced cervical cancer treatment.

Photoimmunotherapy for cancer treatment based on organic small molecules: Recent strategies and future directions.

Photodynamic therapy (PDT) is considered as a promising anticancer approach, owning to its high efficiency and spatiotemporal selectivity. Ample evidence indicated that PDT can trigger immunogenic cell death by releasing antigens that activate immune cells to promote anti-tumor immunity. Nevertheless, the inherent nature of tumors and their complex heterogeneity often limits the efficiency of PDT, which can be overcome with a novel strategy of photo-immunotherapy (PIT) strategy. By exploring the principles of PDT induction and ICD enhancement, combined with other therapies such as chemotherapy or immune checkpoint blockade, the tailored solutions can be designed to address specific challenges of drug resistance, hypoxic conditions, and tumor immunosuppressive microenvironments (TIMEs), which enables targeted enhancement of systemic immunity to address most distant and recurrent cancers. The present article summarizes the specific strategies of PIT and discusses recent existing limitations. More importantly, we anticipate that the perspectives presented herein will help address the clinical translation challenges associated with PIT.

Mechanism exploration of synergistic photo-immunotherapy strategy based on a novel exosome-like nanosystem for remodeling the immune microenvironment of HCC.

The immunosuppressive tumor microenvironment (TME) has become a major challenge in cancer immunotherapy, with abundant tumor-associated macrophages (TAMs) playing a key role in promoting tumor immune escape by displaying an immunosuppressive (M2) phenotype. Recently, it was reported that M1 macrophage-derived nanovesicles (M1NVs) can reprogram TAMs to an anti-tumor M1 phenotype, thereby significantly alleviating the immunosuppressive TME and enhancing the anti-tumor efficacy of immunotherapy. Herein, we developed M1NVs loaded with mesoporous dopamine (MPDA) and indocyanine green (ICG), which facilitated the recruitment of M2 TAMs through synergistic photothermal and photodynamic therapy. Thereafter, M1NVs can induce M1 repolarization of TAMs, resulting in increased infiltration of cytotoxic T lymphocytes within the tumor to promote tumor regression. This study investigated the effect of phototherapy on the immune environment of liver cancer using single-cell RNA sequencing (scRNA-seq) by comparing HCC tissues before and after MPDA/ICG@M1NVs + NIR treatment. The results showed significant shifts in cell composition and gene expression, with decreases in epithelial cells, B cells, and macrophages and increases in neutrophils and myeloid cells. Additionally, gene analysis indicated a reduction in pro-inflammatory signals and immunosuppressive functions, along with enhanced B-cell function and anti-tumor immunity, downregulation of the Gtsf1 gene in the epithelial cells of the MPDA/ICG @M1NVs + NIR group, and decreased expression of the lars2 gene in immune subpopulations. Eno3 expression is reduced in M1 macrophages, whereas Clec4a3 expression is downregulated in M2 macrophages. Notably, the B cell population decreased, whereas Pou2f2 expression increased. These genes regulate cell growth, death, metabolism, and tumor environment, indicating their key role in HCC progression. This study highlights the potential for understanding cellular and molecular dynamics to improve immunotherapy.

Functional co-delivery nanoliposomes based on improving hypoxia for increasing photoimmunotherapy efficacy of cold tumors.

Cold tumors lack T cells infiltration and have low immunogenicity, resulting insufficient immunotherapy response. Therefore, how to realize the transformation from cold tumor to hot tumor is an urgent problem to be solved. Photodynamic therapy can induce immunogenic death of tumor cells (ICD) and activate T lymphocytes to produce tumor immune response. However, hypoxia in the cold tumor microenvironment limits the effectiveness of photodynamic therapy. So in this article, MET-HMME/CAT-HMME@Nlip as a functional co-delivery nanoliposomes was constructed based on overcoming the above problems. Firstly, the oxygen-deficient state could be improved by the following two ways, one is catalase loaded in CAT-HMME@Nlip can decompose high concentration hydrogen peroxide to produce oxygen, and the other is metformin loaded in MET-HMME@Nlip can decrease oxygen consumption by inhibiting of mitochondrial respiration. And then with the increase of substrate oxygen concentration, the sensitivity of photodynamic therapy can be greatly improved and the anti-tumor immune response by PDT-induced ICD can also be enhanced obviously. In addition, metformin could act as a small molecule immune checkpoint inhibitor to reduce the expression of PD-L1 on the surface of tumor cells, thereby effectively improving the specific killing ability of cytotoxic T cells to tumor cells which could not only erasing the primary tumor, but also inhibiting the growth of simulated distant tumors through the immune memory function. This study provides a new idea for improving the clinical treatment effect of hypoxic cold tumors, especially for tumors that could not benefit from immunotherapy due to low or no expression of PD-L1 protein on the surface of tumor cells.

Feasibility of Near-infrared Photoimmunotherapy Combined With Immune Checkpoint Inhibitor Therapy in Unresectable Head and Neck Cancer.

BACKGROUND/AIM: Near-infrared photoimmunotherapy (NIR-PIT) is a recently developed cancer treatment modality that selectively kills cancer cells and may induce a therapeutic host immune response. The aim of this study was to determine the feasibility of combining NIR-PIT with immune checkpoint inhibitor (ICI) therapy for unresectable recurrent head and neck cancer. PATIENTS AND METHODS: Five patients underwent NIR-PIT at Ryukyu University Hospital between January 2022 and April 2024. These patients had unresectable recurrent head and neck squamous cell carcinoma. Among these five patients, four received a combination NIR-PIT and pembrolizumab administration. RESULTS: A total of seven lesions in the oropharynx and oral cavity were targeted. One patient was treated for three different target lesions. The best observed response (BOR) rate was 100%, with three complete responses and four partial responses. The most common treatment-related adverse event was Grade 1 or 2 local pain lasting one to two days postoperatively, which occurred in all patients. Grade 3 adverse events occurred in three cases (42.9%), including pneumonia, pharynx-cutaneous fistula, and trismus. Three patients received ICI therapy following NIR-PIT, achieving a 60% BOR rate. No immune-related adverse events were noted, and the aforementioned Grade 3 adverse events did not worsen during ICI therapy. At a median follow-up of 376 days (range=157-845 days), four target lesions showed no recurrence, while three had recurred. All five patients were alive, including three with no evidence of disease. CONCLUSION: The combination of NIR-PIT and ICI therapy for unresectable recurrent head and neck cancer was feasible.

Near-infrared photoimmunotherapy as a complementary modality to in situ vaccine in a preclinical pancreatic cancer model.

Pancreatic cancer is one of the most refractory malignancies. In situ vaccines (ISV), in which intratumorally injected immunostimulatory adjuvants activate innate immunity at the tumor site, utilize tumor-derived patient-specific antigens, thereby allowing for the development of vaccines in patients themselves. Near-infrared photoimmunotherapy (NIR-PIT) is a novel therapy that selectively kills cancer cells exclusively in the NIR-irradiated region. Extending our previous research showing that ISV using the unique nanoparticulate Toll-like receptor 9 (TLR9) ligand K3-SPG induced effective antitumor immunity, here we incorporated NIR-PIT into K3-SPG-ISV so that local tumor destruction by NIR-PIT augments the antitumor effect of ISV. In the mouse model of pancreatic cancer, the combination of K3-SPG-ISV and CD44-targeting NIR-PIT showed synergistic systemic antitumor effects and enhanced anti-programmed cell death-1 (PD-1) blockade. Mechanistically, strong intratumoral upregulation of interferon-related genes and dependency on CD8+ T cells were observed, suggesting the possible role of interferon and cytotoxic T cell responses in the induction of antitumor immunity. Importantly, this combination induced immunological memory in therapeutic and neoadjuvant settings. This study represents the first attempt to integrate NIR-PIT with ISV, offering a promising new direction for cancer immunotherapy, particularly for pancreatic cancer.

Evaluation of a Novel Lateral Emitting Laser Fiber for Near-Infrared Photoimmunotherapy.

Near-infrared photoimmunotherapy (NIR-PIT) is a new cancer therapy that uses NIR light and conjugates of a tumor-targeting monoclonal antibody and phthalocyanine dye. In clinical practice, frontal and cylindrical diffusers are the only options for NIR illumination. However, illumination in a narrow space is technically difficult with such diffusers. Therefore, we evaluated a lateral illumination system using a lateral emitting laser (LEL) fiber. The LEL fiber illuminated a certain area in a lateral direction. NIR-PIT with an LEL fiber reduced luciferase activity in a light-dose-dependent manner in A431-GFP-luc cells in vitro and significantly suppressed tumor proliferation in a xenograft mouse model. To evaluate the usefulness of the LEL fiber in the illumination of a narrow space, a tumor was illuminated from the inside of a cylinder, mimicking a narrow space, and the fluorescence intensity in the tumor was monitored. In the frontal diffuser, NIR light was unevenly delivered and little light reached a distal tumor area from the illuminated side. By contrast, the LEL fiber allowed a uniform illumination of the entire tumor, and a loss of fluorescence was observed even in distal areas. These findings suggested that the LEL fiber can be used for NIR-PIT and is suitable for NIR light illumination in a narrow space.

Harnessing Dual Phototherapy and Immune Activation for Cancer Treatment: The Development and Application of BODIPY@F127 Nanoparticles.

Conventional phototherapeutic agents are typically used in either photodynamic therapy (PDT) or photothermal therapy (PTT). However, efficacy is often hindered by hypoxia and elevated levels of heat shock proteins in the tumor microenvironment (TME). To address these limitations, a formylated, near-infrared (NIR)-absorbing and heavy-atom-free Aza-BODIPY dye is presented that exhibits both type-I and type-II PDT actions with a high yield of reactive oxygen species (ROS) and manifests efficient photothermal conversion by precise adjustments to the conjugate structure and electron distribution, leading to a large amount of ROS production even under severe hypoxia. To improve biosafety and water solubility, the dye with an amphiphilic triblock copolymer (Pluronic F-127), yielding BDP-6@F127 nanoparticles (NPs) is coated. Furthermore, inspired by the fact that phototherapy triggers the release of tumor-associated antigens, a strategy that leverages potential immune activation by combining PDT/PTT with immune checkpoint blockade (ICB) therapy to amplify the systemic immune response and achieve the much-desired abscopal effect is developed. In conclusion, this study presents a promising molecular design strategy that integrates multimodal therapeutics for a precise and effective approach to cancer therapy.

GSH-responsive bithiophene Aza-BODIPY@HMON nanoplatform for achieving triple-synergistic photoimmunotherapy.

Photoimmunotherapy represents an innovative approach to enhancing the efficiency of immunotherapy in cancer treatment. This approach involves the fusion of immunotherapy and phototherapy (encompassing techniques like photodynamic therapy (PDT) and photothermal therapy (PTT)). Boron-dipyrromethene (BODIPY) has the potential to trigger immunotherapy owing to its excellent PD and PT efficiency. However, the improvements in water solubility, bioavailability, PD/PT combined efficiency, and tumor tissue targeting of BODIPY require introduction of suitable carriers for potential practical application. Herein, a disulfide bond-based hollow mesoporous organosilica (HMON) with excellent biocompatibility and GSH-responsive degradation properties was used as a carrier to load a bithiophene Aza-BODIPY dye (B5), constructing a sample chemotherapy reagent-free B5@HMON nanoplatform achieving triple-synergistic photoimmunotherapy. HMON, involving disulfide bond, is utilized to improve water solubility, tumor tissue targeting, and PD efficiency by depleting GSH and enhancing host-guest interaction between B5 and HMO. The study reveals that HMON's large specific surface area and porous properties significantly enhance the light collection and oxygen adsorption capacity. The HMON's rich mesoporous structure and internal cavity achieved a loading rate of B5 at 11 %. It was found that the triple-synergistic nanoplatform triggered a stronger anti-tumor immune response, including tumor invasion, cytokine production, calreticulin translocation, and dendritic cell maturation, eliciting specific tumor-specific immunological responses in vivo and in vitro. The BALB/c mouse model with 4T1 tumors was used to assess tumor suppression efficiency in vivo, showing that almost all tumors in the B5@HMON group disappeared after 14 days. Such a simple chemotherapy reagent-free B5@HMON nanoplatform achieved triple-synergistic photoimmunotherapy.

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.

Self-assembly of a ruthenium-based cGAS-STING photoactivator for carrier-free cancer immunotherapy.

The cGAS (cyclic GMP-AMP synthase)-STING (stimulator of interferon genes) pathway promotes antitumor immune responses by sensing cytosolic DNA fragments leaked from nucleus and mitochondria. Herein, we designed a highly charged ruthenium photosensitizer (Ru1) with a ß-carboline alkaloid derivative as the ligand for photo-activating of the cGAS-STING pathway. Due to the formation of multiple non-covalent intermolecular interactions, Ru1 can self-assemble into carrier-free nanoparticles (NPs). By incorporating the triphenylphosphine substituents, Ru1 can target and photo-damage mitochondrial DNA (mtDNA) to cause the cytoplasmic DNA leakage to activate the cGAS-STING pathway. Finally, Ru1 NPs show potent antitumor effects and elicit intense immune responses in vivo. In conclusion, we report the first self-assembling mtDNA-targeted photosensitizer, which can effectively activate the cGAS-STING pathway, thus providing innovations for the design of new photo-immunotherapeutic agents.