Regulatory approval of photoimmunotherapy: photodynamic therapy that induces immunogenic cell death

Antibody-drug conjugates for targeted cancer therapy: Recent advances in potential payloads

Antibody-drug conjugates (ADCs) represent a promising cancer therapy modality which specifically delivers highly toxic payloads to cancer cells through antigen-specific monoclonal antibodies (mAbs). To date, 15 ADCs have been approved and more than 100 ADC candidates have advanced to clinical trials for the treatment of various cancers. Among these ADCs, microtubule-targeting and DNA-damaging agents are at the forefront of payload development. However, several challenges including toxicity and drug resistance limit the potential of this modality. To tackle these issues, multiple innovative payloads such as immunomodulators and proteolysis targeting chimeras (PROTACs) are incorporated into ADCs to enable multimodal cancer therapy. In this review, we describe the mechanism of ADCs, highlight the importance of ADC payloads and summarize recent progresses of conventional and unconventional ADC payloads, trying to provide an insight into payload diversification as a key step in future ADC development.

Therapeutic antibodies in oncology: an immunopharmacological overview

The biotechnological development of monoclonal antibodies and their immunotherapeutic use in oncology have grown exponentially in the last decade, becoming the first-line therapy for some types of cancer. Their mechanism of action is based on the ability to regulate the immune system or by interacting with targets that are either overexpressed in tumor cells, released into the extracellular milieu or involved in processes that favor tumor growth. In addition, the intrinsic characteristics of each subclass of antibodies provide specific effector functions against the tumor by activating antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, and antibody-dependent cellular phagocytosis, among other mechanisms. The rational design and engineering of monoclonal antibodies have improved their pharmacokinetic and pharmacodynamic features, thus optimizing the therapeutic regimens administered to cancer patients and improving their clinical outcomes. The selection of the immunoglobulin G subclass, modifications to its crystallizable region (Fc), and conjugation of radioactive substances or antineoplastic drugs may all improve the antitumor effects of therapeutic antibodies. This review aims to provide insights into the immunological and pharmacological aspects of therapeutic antibodies used in oncology, with a rational approach at molecular modifications that can be introduced into these biological tools, improving their efficacy in the treatment of cancer.

Targeting EGFR with molecular degraders as a promising strategy to overcome resistance to EGFR inhibitors

Abnormal activation of EGFR is often associated with various malignant tumors, making it an important target for antitumor therapy. However, traditional targeted inhibitors have several limitations, such as drug resistance and side effects. Many studies have focused on the development of EGFR degraders to overcome this resistance and enhance the therapeutic effect on tumors. Proteolysis targeting chimeras (PROTAC) and Lysosome-based degradation techniques have made significant progress in degrading EGFR. This review provides a summary of the structural and function of EGFR, the resistance, particularly the research progress and activity of EGFR degraders via the proteasome and lysosome. Furthermore, this review aims to provide insights for the development of the novel EGFR degraders.

Unlocking the potential of bispecific ADCs for targeted cancer therapy

Antibody-drug conjugates (ADCs) are biologically targeted drugs composed of antibodies and cytotoxic drugs connected by linkers. These innovative compounds enable precise drug delivery to tumor cells, minimizing harm to normal tissues and offering excellent prospects for cancer treatment. However, monoclonal antibody-based ADCs still present challenges, especially in terms of balancing efficacy and safety. Bispecific antibodies are alternatives to monoclonal antibodies and exhibit superior internalization and selectivity, producing ADCs with increased safety and therapeutic efficacy. In this review, we present available evidence and future prospects regarding the use of bispecific ADCs for cancer treatment, including a comprehensive overview of bispecific ADCs that are currently in clinical trials. We offer insights into the future development of bispecific ADCs to provide novel strategies for cancer treatment.

Components, Formulations, Deliveries, and Combinations of Tumor Vaccines

Tumor vaccines, an important part of immunotherapy, prevent cancer or kill existing tumor cells by activating or restoring the body's own immune system. Currently, various formulations of tumor vaccines have been developed, including cell vaccines, tumor cell membrane vaccines, tumor DNA vaccines, tumor mRNA vaccines, tumor polypeptide vaccines, virus-vectored tumor vaccines, and tumor-in-situ vaccines. There are also multiple delivery systems for tumor vaccines, such as liposomes, cell membrane vesicles, viruses, exosomes, and emulsions. In addition, to decrease the risk of tumor immune escape and immune tolerance that may exist with a single tumor vaccine, combination therapy of tumor vaccines with radiotherapy, chemotherapy, immune checkpoint inhibitors, cytokines, CAR-T therapy, or photoimmunotherapy is an effective strategy. Given the critical role of tumor vaccines in immunotherapy, here, we look back to the history of tumor vaccines, and we discuss the antigens, adjuvants, formulations, delivery systems, mechanisms, combination therapy, and future directions of tumor vaccines.

Spotlight on ideal target antigens and resistance in antibody-drug conjugates: Strategies for competitive advancement

Antibody-drug conjugates (ADCs) represent a novel and promising approach in targeted therapy, uniting the specificity of antibodies that recognize specific antigens with payloads, all connected by the stable linker. These conjugates combine the best targeted and cytotoxic therapies, offering the killing effect of precisely targeting specific antigens and the potent cell-killing power of small molecule drugs. The targeted approach minimizes the off-target toxicities associated with the payloads and broadens the therapeutic window, enhancing the efficacy and safety profile of cancer treatments. Within precision oncology, ADCs have garnered significant attention as a cutting-edge research area and have been approved to treat a range of malignant tumors. Correspondingly, the issue of resistance to ADCs has gradually come to the fore. Any dysfunction in the steps leading to the ADCs' action within tumor cells can lead to the development of resistance. A deeper understanding of resistance mechanisms may be crucial for developing novel ADCs and exploring combination therapy strategies, which could further enhance the clinical efficacy of ADCs in cancer treatment. This review outlines the brief historical development and mechanism of ADCs and discusses the impact of their key components on the activity of ADCs. Furthermore, it provides a detailed account of the application of ADCs with various target antigens in cancer therapy, the categorization of potential resistance mechanisms, and the current state of combination therapies. Looking forward, breakthroughs in overcoming technical barriers, selecting differentiated target antigens, and enhancing resistance management and combination therapy strategies will broaden the therapeutic indications for ADCs. These progresses are anticipated to advance cancer treatment and yield benefits for patients.

Engineering nanomedicines for immunogenic eradication of cancer cells: Recent trends and synergistic approaches

Resistance to cancer immunotherapy is mainly attributed to poor tumor immunogenicity as well as the immunosuppressive tumor microenvironment (TME) leading to failure of immune response. Numerous therapeutic strategies including chemotherapy, radiotherapy, photodynamic, photothermal, magnetic, chemodynamic, sonodynamic and oncolytic therapy, have been developed to induce immunogenic cell death (ICD) of cancer cells and thereby elicit immunogenicity and boost the antitumor immune response. However, many challenges hamper the clinical application of ICD inducers resulting in modest immunogenic response. Here, we outline the current state of using nanomedicines for boosting ICD of cancer cells. Moreover, synergistic approaches used in combination with ICD inducing nanomedicines for remodeling the TME via targeting immune checkpoints, phagocytosis, macrophage polarization, tumor hypoxia, autophagy and stromal modulation to enhance immunogenicity of dying cancer cells were analyzed. We further highlight the emerging trends of using nanomaterials for triggering amplified ICD-mediated antitumor immune responses. Endoplasmic reticulum localized ICD, focused ultrasound hyperthermia, cell membrane camouflaged nanomedicines, amplified reactive oxygen species (ROS) generation, metallo-immunotherapy, ion modulators and engineered bacteria are among the most innovative approaches. Various challenges, merits and demerits of ICD inducer nanomedicines were also discussed with shedding light on the future role of this technology in improving the outcomes of cancer immunotherapy.

Tertiary Lymphoid Structures Gene Signature Predicts Prognosis and Immune Infiltration Analysis in Head and Neck Squamous Cell Carcinoma

Objectives

This study aims to assess the prognostic implications of gene signature of the tertiary lymphoid structures (TLSs) in head and neck squamous cell carcinoma (HNSCC) and scrutinize the influence of TLS on immune infiltration.

Methods

Patients with HNSCC from the Cancer Genome Atlas were categorized into high/low TLS signature groups based on the predetermined TLS signature threshold. The association of the TLS signature with the immune microenvironment, driver gene mutation status, and tumor mutational load was systematically analyzed. Validation was conducted using independent datasets (GSE41613 and GSE102349).

Results

Patients with a high TLS signature score exhibited better prognosis compared to those with a low TLS signature score. The group with a high TLS signature score had significantly higher immune cell subpopulations compared to the group with a low TLS signature score. Moreover, the major immune cell subpopulations and immune circulation characteristics in the tumor immune microenvironment were positively correlated with the TLS signature. Mutational differences in driver genes were observed between the TLS signature high/low groups, primarily in the cell cycle and NRF2 signaling pathways. Patients with TP53 mutations and high TLS signature scores demonstrated a better prognosis compared to those with TP53 wild-type. In the independent cohort, the relationship between TLS signatures and patient prognosis and immune infiltration was also confirmed. Additionally, immune-related biological processes and signaling pathways were activated with elevated TLS signature.

Conclusion

High TLS signature is a promising independent prognostic factor for HNSCC patients. Immunological analysis indicated a correlation between TLS and immune cell infiltration in HNSCC. These findings provide a theoretical basis for future applications of TLS signature in HNSCC prognosis and immunotherapy.

Nanomaterials-Involved Tumor-Associated Macrophages' Reprogramming for Antitumor Therapy

Tumor-associated macrophages (TAMs) play pivotal roles in tumor development. As primary contents of tumor environment (TME), TAMs secrete inflammation-related substances to regulate tumoral occurrence and development. There are two kinds of TAMs: the tumoricidal M1-like TAMs and protumoral M2-like TAMs. Reprogramming TAMs from immunosuppressive M2 to immunocompetent M1 phenotype is considered a feasible way to improve immunotherapeutic efficiency. Notably, nanomaterials show great potential for biomedical fields due to their controllable structures and properties. There are many types of nanomaterials that exhibit great regulatory activities for TAMs' reprogramming. In this review, the recent progress of nanomaterials-involved TAMs' reprogramming is comprehensively discussed. The various nanomaterials for TAMs' reprogramming and the reprogramming strategies are summarized and introduced. Additionally, the challenges and perspectives of TAMs' reprogramming for efficient therapy are discussed, aiming to provide inspiration for TAMs' regulator design and promote the development of TAMs-mediated immunotherapy.

Drug conjugates for the treatment of lung cancer: from drug discovery to clinical practice

A drug conjugate consists of a cytotoxic drug bound via a linker to a targeted ligand, allowing the targeted delivery of the drug to one or more tumor sites. This approach simultaneously reduces drug toxicity and increases efficacy, with a powerful combination of efficient killing and precise targeting. Antibody‒drug conjugates (ADCs) are the best-known type of drug conjugate, combining the specificity of antibodies with the cytotoxicity of chemotherapeutic drugs to reduce adverse reactions by preferentially targeting the payload to the tumor. The structure of ADCs has also provided inspiration for the development of additional drug conjugates. In recent years, drug conjugates such as ADCs, peptide‒drug conjugates (PDCs) and radionuclide drug conjugates (RDCs) have been approved by the Food and Drug Administration (FDA). The scope and application of drug conjugates have been expanding, including combination therapy and precise drug delivery, and a variety of new conjugation technology concepts have emerged. Additionally, new conjugation technology-based drugs have been developed in industry. In addition to chemotherapy, targeted therapy and immunotherapy, drug conjugate therapy has undergone continuous development and made significant progress in treating lung cancer in recent years, offering a promising strategy for the treatment of this disease. In this review, we discuss recent advances in the use of drug conjugates for lung cancer treatment, including structure-based drug design, mechanisms of action, clinical trials, and side effects. Furthermore, challenges, potential approaches and future prospects are presented.

Novel Carrier-Free Nanodrug Enhances Photodynamic Effects by Blocking the Autophagy Pathway and Synergistically Triggers Immunogenic Cell Death for the Efficient Treatment of Breast Cancer

Photosensitizers have been widely used to cause intratumoral generation of reactive oxygen species (ROS) for cancer therapy, but they are easily disturbed by the autophagy pathway, a self-protective mechanism by mitigating oxidative damage. Hereby, we reported a simple and effective strategy to construct a carrier-free nanodrug, Ce6@CQ namely, based on the self-assembly of the photosensitizer chlorin e6 (Ce6) and the autophagy inhibitor chloroquine (CQ). Specifically, Ce6@CQ avoided the unexpected toxicity caused by the regular nanocarrier and also ameliorated its stability in different conditions. Light-activated Ce6 generated cytotoxic ROS and elicited part of the immunogenic cell death (ICD). Moreover, CQ induced autophagy dysfunction, which hindered self-healing in tumor cells and enhanced photodynamic therapy (PDT) to exert a more potent killing effect and more efficient ICD. Also, Ce6@CQ could effectively accumulate in the xenograft breast tumor site in a mouse model through the enhanced permeability and retention (EPR) effect, and the growth of breast tumors was effectively inhibited by Ce6@CQ with light. Such a carrier-free nanodrug provided a new strategy to improve the efficacy of PDT via the suppression of autophagy to digest ROS-induced toxic substances.

Co-Packaged PARP inhibitor and photosensitizer for targeted photo-chemotherapy of 3D ovarian cancer spheroids

BACKGROUND

Within the last decade, poly(ADP-ribose) polymerase inhibitors (PARPi) have emerged in the clinic as an effective treatment for numerous malignancies. Preclinical data have demonstrated powerful combination effects of PARPi paired with photodynamic therapy (PDT), which involves light-activation of specialized dyes (photosensitizers) to stimulate cancer cell death through reactive oxygen species generation.

RESULTS

In this report, the most potent clinical PARP inhibitor, talazoparib, is loaded into the core of a polymeric nanoparticle (NP-Tal), which is interfaced with antibody-photosensitizer conjugates (photoimmunoconjugates, PICs) to form PIC-NP-Tal. In parallel, a new 3D fluorescent coculture model is developed using the parental OVCAR-8-DsRed2 and the chemo-resistant subline, NCI/ADR-RES-EGFP. This model enables quantification of trends in the evolutionary dynamics of acquired chemoresistance in response to various treatment regimes. Results reveal that at a low dosage (0.01 μM), NP-Tal kills the parental cells while sparing the chemo-resistant subline, thereby driving chemoresistance. Next, PIC-NP-Tal and relevant controls are evaluated in the 3D coculture model at multiple irradiation doses to characterize effects on total spheroid ablation and relative changes in parental and subline cell population dynamics. Total spheroid ablation data shows potent combination effects when PIC and NP-Tal are co-administered, but decreased efficacy with the conjugated formulation (PIC-NP-Tal). Analysis of cell population dynamics reveals that PIC, BPD + NP-Tal, PIC + NP-Tal, and PIC-NP-Tal demonstrate selection pressures towards chemoresistance.

CONCLUSIONS

This study provides key insights into manufacturing parameters for PARPi-loaded nanoparticles, as well as the potential role of PDT-based combination therapies in the context of acquired drug resistance.

Near-Infrared-Responsive Rare Earth Nanoparticles for Optical Imaging and Wireless Phototherapy

Near-infrared (NIR) light is well-suited for the optical imaging and wireless phototherapy of malignant diseases because of its deep tissue penetration, low autofluorescence, weak tissue scattering, and non-invasiveness. Rare earth nanoparticles (RENPs) are promising NIR-responsive materials, owing to their excellent physical and chemical properties. The 4f electron subshell of lanthanides, the main group of rare earth elements, has rich energy-level structures. This facilitates broad-spectrum light-to-light conversion and the conversion of light to other forms of energy, such as thermal and chemical energies. In addition, the abundant loadable and modifiable sites on the surface offer favorable conditions for the functional expansion of RENPs. In this review, the authors systematically discuss the main processes and mechanisms underlying the response of RENPs to NIR light and summarize recent advances in their applications in optical imaging, photothermal therapy, photodynamic therapy, photoimmunotherapy, optogenetics, and light-responsive drug release. Finally, the challenges and opportunities for the application of RENPs in optical imaging and wireless phototherapy under NIR activation are considered.

Current Advances in Photodynamic Therapy (PDT) and the Future Potential of PDT-Combinatorial Cancer Therapies

Photodynamic therapy (PDT) is a two-stage treatment that implies the use of light energy, oxygen, and light-activated compounds (photosensitizers) to elicit cancerous and precancerous cell death after light activation (phototoxicity). The biophysical, bioengineering aspects and its combinations with other strategies are highlighted in this review, both conceptually and as they are currently applied clinically. We further explore the recent advancements of PDT with the use of nanotechnology, including quantum dots as innovative photosensitizers or energy donors as well as the combination of PDT with radiotherapy and immunotherapy as future promising cancer treatments. Finally, we emphasize the potential significance of organoids as physiologically relevant models for PDT.

Antitumor Immunity Mediated by Photodynamic Therapy Using Injectable Chitosan Hydrogels for Intratumoral and Sustained Drug Delivery

Photodynamic therapy (PDT) is an anticancer therapy with proven efficacy; however, its application is often limited by prolonged skin photosensitivity and solubility issues associated with the phototherapeutic agents. Injectable hydrogels which can effectively provide intratumoral delivery of photosensitizers with sustained release are attracting increased interest for photodynamic cancer therapies. However, most of the hydrogels for PDT applications are based on systems with high complexity, and often, preclinical validation is not provided. Herein, we provide a simple and reliable pH-sensitive hydrogel formulation that presents appropriate rheological properties for intratumoral injection. For this, Temoporfin (m-THPC), which is one of the most potent clinical photosensitizers, was chemically modified to introduce functional groups that act as cross-linkers in the formation of chitosan-based hydrogels. The introduction of -COOH groups resulted in a water-soluble derivative, named PS2, that was the most promising candidate. Although PS2 was not internalized by the target cells, its extracellular activation caused effective damage to the cancer cells, which was likely mediated by lipid peroxidation. The injection of the hydrogel containing PS2 in the tumors was monitored by high-frequency ultrasounds and in vivo fluorescence imaging which confirmed the sustained release of PS2 for at least 72 h. Following local administration, light exposure was conducted one (single irradiation protocol) or three (multiple irradiation protocols) times. The latter delivered the best therapeutic outcomes, which included complete tumor regression and systemic anticancer immune responses. Immunological memory was induced as ∼75% of the mice cured with our strategy rejected a second rechallenge with live cancer cells. Additionally, the failure of PDT to treat immunocompromised mice bearing tumors reinforces the relevance of the host immune system. Finally, our strategy promotes anticancer immune responses that lead to the abscopal protection against distant metastases.

The Evolving Landscape of Antibody-Drug Conjugates: In Depth Analysis of Recent Research Progress

Antibody-drug conjugates (ADCs) are targeted immunoconjugate constructs that integrate the potency of cytotoxic drugs with the selectivity of monoclonal antibodies, minimizing damage to healthy cells and reducing systemic toxicity. Their design allows for higher doses of the cytotoxic drug to be administered, potentially increasing efficacy. They are currently among the most promising drug classes in oncology, with efforts to expand their application for nononcological indications and in combination therapies. Here we provide a detailed overview of the recent advances in ADC research and consider future directions and challenges in promoting this promising platform to widespread therapeutic use. We examine data from the CAS Content Collection, the largest human-curated collection of published scientific information, and analyze the publication landscape of recent research to reveal the exploration trends in published documents and to provide insights into the scientific advances in the area. We also discuss the evolution of the key concepts in the field, the major technologies, and their development pipelines with company research focuses, disease targets, development stages, and publication and investment trends. A comprehensive concept map has been created based on the documents in the CAS Content Collection. We hope that this report can serve as a useful resource for understanding the current state of knowledge in the field of ADCs and the remaining challenges to fulfill their potential.

Gold standard assessment of immunogenic cell death induced by photodynamic therapy: From in vitro to tumor mouse models and anti-cancer vaccination strategies

The discovery of the concept of immunogenic cell death (ICD) is a cornerstone in the development of novel anti-cancer immunotherapeutic approaches. Induction of the ICD pathway by specific anti-cancer therapeutic regimens can eliminate cancer cells by directly killing them during therapy and by activation of strong and specific anti-cancer immunity, leading to a long-lasting immunological memory that prevents cancer recurrence. ICD encompasses different forms of regulated cell death and can be triggered by many anti-cancer treatment modalities, including photodynamic therapy (PDT). PDT is a multistep procedure involving the accumulation of a light-sensitive dye known as a photosensitizer (PS) in tumor cells, followed by its activation by irradiation with a light of an appropriate wavelength. In the presence of molecular oxygen, the irradiated PS leads to the generation of cytotoxic reactive oxygen species, which can lead to ICD induction in the cancer cells. Here, we first describe in vitro methods to help optimize the PDT procedure for a specific PS. We also provide a collection of protocols and techniques for assessing ICD in vitro, including analysis of the emission of damage associated molecular patterns (DAMPs), efferocytosis, and the maturation and activation state of antigen presenting cells. Next, we describe in detail protocols for diverse tumor mouse models for assessing and characterizing ICD in vivo, such as murine tumor vaccination models. Finally, as an immunotherapeutic vaccine, we suggest using either PDT-induced dead cancer cells, preferably undergoing ICD, or dendritic cells loaded with lysates of PDT-induced cancer cells in a syngeneic orthotopic glioma model. Overall, this methodological article provides a quantitative, comprehensive set of validated tools that can be successfully used, with some adaptations, to identify, optimize and validate novel PSs in vitro and in vivo for the efficient induction of ICD during photodynamic treatment.

Antibody-drug conjugates: Recent advances in payloads

Antibody‒drug conjugates (ADCs), which combine the advantages of monoclonal antibodies with precise targeting and payloads with efficient killing, show great clinical therapeutic value. The ADCs' payloads play a key role in determining the efficacy of ADC drugs and thus have attracted great attention in the field. An ideal ADC payload should possess sufficient toxicity, low immunogenicity, high stability, and modifiable functional groups. Common ADC payloads include tubulin inhibitors and DNA damaging agents, with tubulin inhibitors accounting for more than half of the ADC drugs in clinical development. However, due to clinical limitations of traditional ADC payloads, such as inadequate efficacy and the development of acquired drug resistance, novel highly efficient payloads with diverse targets and reduced side effects are being developed. This perspective summarizes the recent research advances of traditional and novel ADC payloads with main focuses on the structure-activity relationship studies, co-crystal structures, and designing strategies, and further discusses the future research directions of ADC payloads. This review also aims to provide valuable references and future directions for the development of novel ADC payloads that will have high efficacy, low toxicity, adequate stability, and abilities to overcome drug resistance.

A comprehensive overview on antibody-drug conjugates: from the conceptualization to cancer therapy

Antibody-Drug Conjugates (ADCs) represent an innovative class of potent anti-cancer compounds that are widely used in the treatment of hematologic malignancies and solid tumors. Unlike conventional chemotherapeutic drug-based therapies, that are mainly associated with modest specificity and therapeutic benefit, the three key components that form an ADC (a monoclonal antibody bound to a cytotoxic drug via a chemical linker moiety) achieve remarkable improvement in terms of targeted killing of cancer cells and, while sparing healthy tissues, a reduction in systemic side effects caused by off-tumor toxicity. Based on their beneficial mechanism of action, 15 ADCs have been approved to date by the market approval by the Food and Drug Administration (FDA), the European Medicines Agency (EMA) and/or other international governmental agencies for use in clinical oncology, and hundreds are undergoing evaluation in the preclinical and clinical phases. Here, our aim is to provide a comprehensive overview of the key features revolving around ADC therapeutic strategy including their structural and targeting properties, mechanism of action, the role of the tumor microenvironment and review the approved ADCs in clinical oncology, providing discussion regarding their toxicity profile, clinical manifestations and use in novel combination therapies. Finally, we briefly review ADCs in other pathological contexts and provide key information regarding ADC manufacturing and analytical characterization.

Recent Studies in Photodynamic Therapy for Cancer Treatment: From Basic Research to Clinical Trials

Photodynamic therapy (PDT) is an emerging and less invasive treatment modality for various types of cancer. This review provides an overview of recent trends in PDT research, ranging from basic research to ongoing clinical trials, focusing on different cancer types. Lung cancer, head and neck cancer, non-melanoma skin cancer, prostate cancer, and breast cancer are discussed in this context. In lung cancer, porfimer sodium, chlorin e6, and verteporfin have shown promising results in preclinical studies and clinical trials. For head and neck cancer, PDT has demonstrated effectiveness as an adjuvant treatment after surgery. PDT with temoporfin, redaporfin, photochlor, and IR700 shows potential in early stage larynx cancer and recurrent head and neck carcinoma. Non-melanoma skin cancer has been effectively treated with PDT using methyl aminolevulinate and 5-aminolevulinic acid. In prostate cancer and breast cancer, PDT research is focused on developing targeted photosensitizers to improve tumor-specific uptake and treatment response. In conclusion, PDT continues to evolve as a promising cancer treatment strategy, with ongoing research spanning from fundamental investigations to clinical trials, exploring various photosensitizers and treatment combinations. This review sheds light on the recent advancements in PDT for cancer therapy and highlights its potential for personalized and targeted treatments.

Trial watch: an update of clinical advances in photodynamic therapy and its immunoadjuvant properties for cancer treatment

Photodynamic therapy (PDT) is a medical treatment used to target solid tumors, where the administration of a photosensitizing agent and light generate reactive oxygen species (ROS), thus resulting in strong oxidative stress that selectively damages the illuminated tissues. Several preclinical studies have demonstrated that PDT can prime the immune system to recognize and attack cancer cells throughout the body. However, there is still limited evidence of PDT-mediated anti-tumor immunity in clinical settings. In the last decade, several clinical trials on PDT for cancer treatment have been initiated, indicating that significant efforts are being made to improve current PDT protocols. However, most of these studies disregarded the immunological dimension of PDT. The immunomodulatory properties of PDT can be combined with standard therapy and/or emerging immunotherapies, such as immune checkpoint blockers (ICBs), to achieve better disease control. Combining PDT with immunotherapy has shown synergistic effects in some preclinical models. However, the value of this combination in patients is still unknown, as the first clinical trials evaluating the combination of PDT with ICBs are just being initiated. Overall, this Trial Watch provides a summary of recent clinical information on the immunomodulatory properties of PDT and ongoing clinical trials using PDT to treat cancer patients. It also discusses the future perspectives of PDT for oncological indications.

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

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

Immuno-photodynamic Therapy (IPDT): Organic Photosensitizers and Their Application in Cancer Ablation

Photosensitizer-based photodynamic therapy (PDT) has been considered as a promising modality for fighting diverse types of cancers. PDT directly inhibits local tumors by a minimally invasive strategy, but it seems to be incapable of achieving complete eradication and fails to prevent metastasis and recurrence. Recently, increasing events proved that PDT was associated with immunotherapy by triggering immunogenic cell death (ICD). Upon a specific wavelength of light irradiation, the photosensitizers will turn the surrounding oxygen molecules into cytotoxic reactive oxygen species (ROS) for killing the cancer cells. Simultaneously, the dying tumor cells release tumor-associated antigens, which could improve immunogenicity to activate immune cells. However, the progressively enhanced immunity is typically limited by the intrinsic immunosuppressive tumor microenvironment (TME). To overcome this obstacle, immuno-photodynamic therapy (IPDT) has come to be one of the most beneficial strategies, which takes advantage of PDT to stimulate the immune response and unite immunotherapy for inducing immune-OFF tumors to immune-ON ones, to achieve systemic immune response and prevent cancer recurrence. In this Perspective, we provide a review of recent advances in organic photosensitizer-based IPDT. The general process of immune responses triggered by photosensitizers (PSs) and how to enhance the antitumor immune pathway by modifying the chemical structure or conjugating with a targeting component was discussed. In addition, future perspectives and challenges associated with IPDT strategies are also discussed. We hope this Perspective could inspire more innovative ideas and provide executable strategies for future developments in the war against cancer.

Enzyme-Responsive Double-Locked Photodynamic Molecular Beacon for Targeted Photodynamic Anticancer Therapy

An advanced photodynamic molecular beacon (PMB) was designed and synthesized, in which a distyryl boron dipyrromethene (DSBDP)-based photosensitizer and a Black Hole Quencher 3 moiety were connected via two peptide segments containing the sequences PLGVR and GFLG, respectively, of a cyclic peptide. These two short peptide sequences are well-known substrates of matrix metalloproteinase-2 (MMP-2) and cathepsin B, respectively, both of which are overexpressed in a wide range of cancer cells either extracellularly (for MMP-2) or intracellularly (for cathepsin B). Owing to the efficient Förster resonance energy transfer between the two components, this PMB was fully quenched in the native form. Only upon interaction with both MMP-2 and cathepsin B, either in a buffer solution or in cancer cells, both of the segments were cleaved specifically, and the two components could be completely separated, thereby restoring the photodynamic activities of the DSBDP moiety. This PMB could also be activated in tumors, and it effectively suppressed the tumor growth in A549 tumor-bearing nude mice upon laser irradiation without causing notable side effects. In particular, it did not cause skin photosensitivity, which is a very common side effect of photodynamic therapy (PDT) using conventional "always-on" photosensitizers. The overall results showed that this "double-locked" PMB functioned as a biological AND logic gate that could only be unlocked by the coexistence of two tumor-associated enzymes, which could greatly enhance the tumor specificity in PDT.

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.

Targeted implementation strategies of precise photodynamic therapy based on clinical and technical demands

With the development of materials science, photodynamic-based treatments have gradually entered clinics. Photodynamic therapy is ideal for cancer treatment due to its non-invasive and spatiotemporal properties and is the first to be widely promoted in clinical practice. However, the shortcomings resulting from the gap between technical and clinical demands, such as phototoxicity, low tissue permeability, and tissue hypoxia, limit its wide applications. This article reviews the available data regarding the pharmacological and clinical factors affecting the efficacy of photodynamic therapy, such as photosensitizers and oxygen supply, disease diagnosis, and other aspects of photodynamic therapy. In addition, the synergistic treatment of photodynamic therapy with surgery and nanotechnology is also discussed, which is expected to provide inspiration for the design of photodynamic therapy strategies.

Cancer-targeted photoimmunotherapy induces antitumor immunity and can be augmented by anti-PD-1 therapy for durable anticancer responses in an immunologically active murine tumor model

The complex immunosuppressive nature of solid tumor microenvironments poses a significant challenge to generating efficacious and durable anticancer responses. Photoimmunotherapy is a cancer treatment strategy by which an antibody is conjugated with a non-toxic light-activatable dye. Following administration of the conjugate and binding to the target tumor, subsequent local laser illumination activates the dye, resulting in highly specific target cell membrane disruption. Here we demonstrate that photoimmunotherapy treatment elicited tumor necrosis, thus inducing immunogenic cell death characterized by the release of damage-associated molecular patterns (DAMPs). Photoimmunotherapy-killed tumor cells activated dendritic cells (DC), leading to the production of proinflammatory cytokines, T cell stimulation, priming antigen-specific T cells, and durable memory T cell responses, which led complete responder mice to effectively reject new tumors upon rechallenge. PD-1 blockade in combination with photoimmunotherapy enhanced overall anticancer efficacy, including against anti-PD-1-resistant tumors. The combination treatment also elicited abscopal anticancer activity, as observed by reduction of distal, non-illuminated tumors, further demonstrating the ability of photoimmunotherapy to harness local and peripheral T cell responses. With this work we therefore delineate the immune mechanisms of action for photoimmunotherapy and demonstrate the potential for cancer-targeted photoimmunotherapy to be combined with other immunotherapy approaches for augmented, durable anticancer efficacy. Moreover, we demonstrate responses utilizing various immunocompetent mouse models, as well as in vitro data from human cells, suggesting broad translational potential.

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.

Dendritic cell transfer for cancer immunotherapy

Dendritic cells (DCs) play a major role in cancer immunosurveillance as they bridge innate and adaptive immunity by detecting tumor-associated antigens and presenting them to T lymphocytes. The adoptive transfer of antigen loaded DCs has been proposed as an immunotherapeutic approach for the treatment of various types of cancer. Nevertheless, despite promising preclinical data, the therapeutic efficacy of DC transfer is still deceptive in cancer patients. Here we summarize recent findings in DC biology with a special focus on the development of actionable therapeutic strategies and discuss experimental and clinical approaches that aim at improving the efficacy of DC-based immunotherapies, including, but not limited to, optimized DC production and antigen loading, stimulated maturation, the co-treatment with additional immunotherapies, as well as the inhibition of DC checkpoints.

Targeting oncogene and non-oncogene addiction to inflame the tumour microenvironment

Immune checkpoint inhibitors (ICIs) have revolutionized the clinical management of multiple tumours. However, only a few patients respond to ICIs, which has generated considerable interest in the identification of resistance mechanisms. One such mechanism reflects the ability of various oncogenic pathways, as well as stress response pathways required for the survival of transformed cells (a situation commonly referred to as 'non-oncogene addiction'), to support tumour progression not only by providing malignant cells with survival and/or proliferation advantages, but also by establishing immunologically 'cold' tumour microenvironments (TMEs). Thus, both oncogene and non-oncogene addiction stand out as promising targets to robustly inflame the TME and potentially enable superior responses to ICIs.

Pembrolizumab in the first-line treatment of advanced head and neck cancer

INTRODUCTION

Recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) is associated with dismal prognosis and has limited therapeutic options. PD-1/PD-L1 axis blockade was initially shown to improve outcomes in platinum-refractory HNSCC. More recently, pembrolizumab monotherapy or pembrolizumab combined with chemotherapy resulted in better overall survival than platinum, 5-fluorouracil, and cetuximab (EXTREME regimen) as first-line therapy for R/M HNSCC, establishing a new standard-of-care therapy for this disease.

AREAS COVERED

We review pembrolizumab in the first-line treatment of R/M HNSCC and summarize the impact of PD-L1 expression, tumor and symptom burden, and patient's performance status on treatment decisions. Future perspectives are summarized.

EXPERT OPINION

The standard-of-care first-line therapy for R/M HNSCC is pembrolizumab monotherapy for patients with a PD-L1 combined positive score (CPS)≥1 or pembrolizumab combined with platinum and 5-fluorouracil for patients with any PD-L1 status. Addition of chemotherapy to pembrolizumab increases the response rate but also toxicity and is preferred for patients with good performance status and significant tumor and symptom burden. For patients with a PD-L1 CPS <1, the EXTREME regimen should be considered. New strategies combining pembrolizumab with targeted therapies and immune checkpoints inhibitors are being explored to synergize or overcome resistance to anti-PD-1.

Use of photoimmunoconjugates to characterize ABCB1 in cancer cells

Accurate detection of ATP-binding cassette drug transporter ABCB1 expression is imperative for precise identification of drug-resistant tumors. Existing detection methods fail to provide the necessary molecular details regarding the functional state of the transporter. Photo-immunoconjugates are a unique class of antibody-dye conjugates for molecular diagnosis and therapeutic treatment. However, conjugating hydrophobic photosensitizers to hydrophilic antibodies is quite challenging. Here, we devise a photoimmunoconjugate that combines a clinically approved benzoporphyrin derivative (BPD) photosensitizer and the conformational-sensitive UIC2 monoclonal antibody to target functionally active human ABCB1 (i.e., ABCB1 in the inward-open conformation). We show that PEGylation of UIC2 enhances the BPD conjugation efficiency and reduces the amount of non-covalently conjugated BPD molecules by 17%. Size exclusion chromatography effectively separates the different molecular weight species found in the UIC2-BPD sample. The binding of UIC2-BPD to ABCB1 was demonstrated in lipidic nanodiscs and ABCB1-overexpressing triple negative breast cancer (TNBC) cells. UIC2-BPD was found to retain the conformation sensitivity of UIC2, as the addition of ABCB1 modulators increases the antibody reactivity in vitro. Thus, the inherent fluorescence capability of BPD can be used to label ABCB1-overexpressing TNBC cells using UIC2-BPD. Our findings provide insight into conjugation of hydrophobic photosensitizers to conformation-sensitive antibodies to target proteins expressed on the surface of cancer cells.

Enhanced anti-tumor efficacy by inhibiting HIF-1α to reprogram TAMs via core-satellite upconverting nanoparticles with curcumin mediated photodynamic therapy

Tumor hypoxic stress after photodynamic therapy (PDT) will be inevitably exacerbated by the vascular blocking effects and oxygen consumption in the tumor microenvironment (TME) which usually leads to compromised efficacy and clinical performance. Increasing evidence links the hypoxia induced up-regulation of hypoxia inducible factor 1α (HIF-1α) with immunosuppressive TME, including the polarization of M2 phenotype tumor associated macrophages (TAMs), which promote the recurrence and metastasis. Here, we reported NIR-triggered core-satellite upconverting nanoparticles (CSNPs) with curcumin (Cur) embedded as a difunctional photosensitizer, which could realize PDT in deep tumors with long excitation wavelength (980 nm) and reverse the immunosuppressive TME induced by up-regulated HIF-1α at the same time. This Cur-loaded CSNPs (Cur-CSNPs)-mediated PDT could successfully induce the immunogenic cell death (ICD) of triple negative breast cancer (TNBC) cell lines (4T1 and MDA-MB-231) in vitro and repolarize the 4T1 cells co-cultured TAMs from pro-tumor M2 to the anti-tumor M1 phenotype. Furthermore, Cur-CSNPs-mediated PDT could suppress the 4T1 tumor growth in primary and distant sites through the synergistic immunotherapeutic effects in vivo by priming M1 type TAMs and CD4+/CD8+ T cells' infiltration. Our data highlight the novel application of CSNPs-embedded Cur as a difunctional photosensitizer to enhance the anti-tumor efficacy of PDT.

Novel anticancer drugs approved in 2020

Cancer is still a major factor threatening human life around the world, and anticancer drugs remain a huge unmet clinical need. Here, we reviewed novel drugs including new molecular entities and new therapeutic biologics approved in the US, EU, Japan, and China that represent the main advances in anticancer drug research and development in 2020. Small molecule inhibitors targeting oncogenes, antibodies, and antibody drug conjugates (ADCs) are the main anticancer drugs that were approved in 2020. More novel anticancer drugs that possess target activity and that overcome drug resistance are anticipated in the future.

Targeting immunogenic cancer cell death by photodynamic therapy: past, present and future

The past decade has witnessed major breakthroughs in cancer immunotherapy. This development has been largely motivated by cancer cell evasion of immunological control and consequent tumor resistance to conventional therapies. Immunogenic cell death (ICD) is considered one of the most promising ways to achieve total tumor cell elimination. It activates the T-cell adaptive immune response and results in the formation of long-term immunological memory. ICD can be triggered by many anticancer treatment modalities, including photodynamic therapy (PDT). In this review, we first discuss the role of PDT based on several classes of photosensitizers, including porphyrins and non-porphyrins, and critically evaluate their potential role in ICD induction. We emphasize the emerging trend of ICD induction by PDT in combination with nanotechnology, which represents third-generation photosensitizers and involves targeted induction of ICD by PDT. However, PDT also has some limitations, including the reduced efficiency of ICD induction in the hypoxic tumor microenvironment. Therefore, we critically evaluate strategies for overcoming this limitation, which is essential for increasing PDT efficiency. In the final part, we suggest several areas for future research for personalized cancer immunotherapy, including strategies based on oxygen-boosted PDT and nanoparticles. In conclusion, the insights from the last several years increasingly support the idea that PDT is a powerful strategy for inducing ICD in experimental cancer therapy. However, most studies have focused on mouse models, but it is necessary to validate this strategy in clinical settings, which will be a challenging research area in the future.

Silicon phthalocyanines: synthesis and resurgent applications

Their unique axial bonds and NIR optical properties have made silicon phthalocyanines (SiPcs) valuable compounds. Herein, we present key synthetic strategies and emerging applications of SiPcs over the past decade.

A photoactivated Ir(iii) complex targets cancer stem cells and induces secretion of damage-associated molecular patterns in melanoma cells characteristic of immunogenic cell death

The new iridium complex selectively targets cancer stem cells and has potential to induce immunogenic cell death in cancer cells.

Current Trends and Future Prospects of Molecular Targeted Therapy in Head and Neck Squamous Cell Carcinoma

In recent years, advances in drug therapy for head and neck squamous cell carcinoma (HNSCC) have progressed rapidly. In addition to cytotoxic anti-cancer agents such as platinum-based drug (cisplatin and carboplatin) and taxane-based drugs (docetaxel and paclitaxel), epidermal growth factor receptor-tyrosine kinase inhibitors (cetuximab) and immune checkpoint inhibitors such as anti-programmed cell death-1 (PD-1) antibodies (nivolumab and pembrolizumab) have come to be used. The importance of anti-cancer drug therapy is increasing year by year. Therefore, we summarize clinical trials of molecular targeted therapy and biomarkers in HNSCC from previous studies. Here we show the current trends and future prospects of molecular targeted therapy in HNSCC.