Noncancerous disease-targeting AIEgens.

Noncancerous diseases include a wide plethora of medical conditions beyond cancer and are a major cause of mortality around the world. Despite progresses in clinical research, many puzzles about these diseases remain unanswered, and new therapies are continuously being sought. The evolution of bio-nanomedicine has enabled huge advancements in biosensing, diagnosis, bioimaging, and therapeutics. The recent development of aggregation-induced emission luminogens (AIEgens) has provided an impetus to the field of molecular bionanomaterials. Following aggregation, AIEgens show strong emission, overcoming the problems associated with the aggregation-caused quenching (ACQ) effect. They also have other unique properties, including low background interferences, high signal-to-noise ratios, photostability, and excellent biocompatibility, along with activatable aggregation-enhanced theranostic effects, which help them achieve excellent therapeutic effects as an one-for-all multimodal theranostic platform. This review provides a comprehensive overview of the overall progresses in AIEgen-based nanoplatforms for the detection, diagnosis, bioimaging, and bioimaging-guided treatment of noncancerous diseases. In addition, it details future perspectives and the potential clinical applications of these AIEgens in noncancerous diseases are also proposed. This review hopes to motivate further interest in this topic and promote ideation for the further exploration of more advanced AIEgens in a broad range of biomedical and clinical applications in patients with noncancerous diseases.

A carrier-free supramolecular nano-twin-drug for overcoming irinotecan-resistance and enhancing efficacy against colorectal cancer.

Irinotecan (Ir) is commonly employed as a first-line chemotherapeutic treatment for colorectal cancer (CRC). However, tremendous impediments remain to be addressed to surmount drug resistance and ameliorate adverse events. Poly-ADP-Ribose Polymerase (PARP) participates in the maintenance of genome stability and the repair of DNA damage, thus playing a critical role in chemotherapy resistance. In this work, we introduce a novel curative strategy that utilizes nanoparticles (NPs) prepared by dynamic supramolecular co-assembly of Ir and a PARP inhibitor (PARPi) niraparib (Nir) through π-π stacking and hydrogen bond interactions. The Ir and Nir self-assembled Nano-Twin-Drug of (Nir-Ir NPs) could enhance the therapeutic effect on CRC by synergistically inhibiting the DNA damage repair pathway and activating the tumor cell apoptosis process without obvious toxicity. In addition, the Nir-Ir NPs could effectively reverse irinotecan-resistance by inhibiting the expression of multiple resistance protein-1 (MRP-1). Overall, our study underscores the distinctive advantages and potential of Nir-Ir NPs as a complementary strategy to chemotherapy by simultaneously overcoming the Ir resistance and improving the anti-tumor efficacy against CRC.

Visualization of human T lymphocyte-mediated eradication of cancer cells in vivo.

Lymphocyte-based immunotherapy has emerged as a breakthrough in cancer therapy for both hematologic and solid malignancies. In a subpopulation of cancer patients, this powerful therapeutic modality converts malignancy to clinically manageable disease. However, the T cell- and chimeric antigen receptor T (CAR-T) cell-mediated antimetastatic activity, especially their impacts on microscopic metastatic lesions, has not yet been investigated. Here we report a living zebrafish model that allows us to visualize the metastatic cancer cell killing effect by tumor- infiltrating lymphocytes (TILs) and CAR-T cells in vivo at the single-cell level. In a freshly isolated primary human melanoma, specific TILs effectively eliminated metastatic cancer cells in the living body. This potent metastasis-eradicating effect was validated using a human lymphoma model with CAR-T cells. Furthermore, cancer-associated fibroblasts protected metastatic cancer cells from T cell-mediated killing. Our data provide an in vivo platform to validate antimetastatic effects by human T cell-mediated immunotherapy. This unique technology may serve as a precision medicine platform for assessing anticancer effects of cellular immunotherapy in vivo before administration to human cancer patients.

Photothermal and Enhanced Photocatalytic Therapies Conduce to Synergistic Anticancer Phototherapy with Biodegradable Titanium Diselenide Nanosheets.

Nanomaterial-based photothermal and photocatalytic therapies are effective against various types of cancers. However, combining two or more materials is considered necessary to achieve the synergistic anticancer effects of photothermal and photocatalytic therapy, which made the preparation process complicated. Herein, the authors describe simple 2D titanium diselenide (TiSe2 ) nanosheets (NSs) that can couple photothermal therapy with photocatalytic therapy. The TiSe2 NSs are prepared using a liquid exfoliation method. They show a layered structure and possess high photothermal conversion efficiency (65.58%) and good biocompatibility. Notably, upon near-infrared irradiation, these NSs exhibit good photocatalytic properties with enhanced reactive oxygen species generation and H2 O2 decomposition in vitro. They can also achieve high temperatures, with heat improving their catalytic ability to further amplify oxidative stress and glutathione depletion in cancer cells. Furthermore, molecular mechanism studies reveal that the synergistic effects of photothermal and enhanced photocatalytic therapy can simultaneously lead to apoptosis and necrosis in cancer cells via the HSP90/JAK3/NF-κB/IKB-α/Caspase-3 pathway. Systemic exploration reveals that the TiSe2 NSs has an appreciable degradation rate and accumulates passively in tumor tissue, where they facilitate photothermal and photocatalytic effects without obvious toxicity. Their study thus indicates the high potential of biodegradable TiSe2 NSs in synergistic phototherapy for cancer treatment.

Emerging combination strategies with phototherapy in cancer nanomedicine.

Optical techniques using developed laser and optical devices have made a profound impact on modern medicine, with "biomedical optics" becoming an emerging field. Sophisticated technologies have been developed in cancer nanomedicine, such as photothermal therapy and photodynamic therapy, among others. However, single-mode phototherapy cannot completely treat persistent tumors, with the challenges of relapse or metastasis remaining; therefore, combinatorial strategies are being developed. In this review, the role of light in cancer therapy and the challenges of phototherapy are discussed. The development of combinatorial strategies with other therapeutic methods, including chemotherapy, immunotherapy, gene therapy, and radiotherapy, is presented and future directions are further discussed. This review aims to highlight the significance of light in cancer therapy and discuss the combinatorial strategies that show promise in addressing the challenges of phototherapy.

Tumor-Exocytosed Exosome/Aggregation-Induced Emission Luminogen Hybrid Nanovesicles Facilitate Efficient Tumor Penetration and Photodynamic Therapy.

The development of novel photosensitizing agents with aggregation-induced emission (AIE) properties has fueled significant advances in the field of photodynamic therapy (PDT). An electroporation method was used to prepare tumor-exocytosed exosome/AIE luminogen (AIEgen) hybrid nanovesicles (DES) that could facilitate efficient tumor penetration. Dexamethasone was then used to normalize vascular function within the tumor microenvironment (TME) to reduce local hypoxia, thereby significantly enhancing the PDT efficacy of DES nanovesicles, and allowing them to effectively inhibit tumor growth. The hybridization of AIEgen and biological tumor-exocytosed exosomes was achieved for the first time, and combined with PDT approaches by normalizing the intratumoral vasculature as a means of reducing local tissue hypoxia. This work highlights a new approach to the design of AIEgen-based PDT systems and underscores the potential clinical value of AIEgens.

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.

Bacteria-targeted delivery of black phosphorus quantum dots facilitates photothermal therapy against hypoxic tumors and complementary low-dose radiotherapy.

Many approaches have been employed to relieve hypoxia in solid tumors to enhance sensitivity to radiotherapy (RT), including O2 delivery or hydrogen peroxide (H2O2) decomposition strategies. To date, however, these modalities have been restricted by poor O2 loading, rapid O2 leakage, and limited endogenous H2O2 levels. To overcome these limitations, we therefore sought to develop an effective approach for the oxygen-independent treatment of hypoxic tumors. In this study, we designed a novel black phosphorus quantum dot (BPQD)/Escherichia coli (E. coli) hybrid system (BE) capable of facilitating the photothermal therapy (PTT) of hypoxic tumors. A simple electrostatic adsorption approach was used to conjugate BPQDs to E. coli. BE is capable of reliably targeting hypoxic tumors and mediating PTT. BPQDs in BE can directly facilitate X-ray-mediated radiosensitization of tumors, thereby achieving significant RT efficacy in response to lower doses of radiation, effectively and specifically damaging hypoxic tumor tissues to suppress the growth of tumors. Our results highlight this BE system as a novel approach to tumor radiosensitization with great potential for clinical application.

A simple strategy for the efficient design of mitochondria-targeting NIR-II phototheranostics.

The pursuit of phototheranostic agents with near-infrared II (NIR-II) emission, high photothermal conversion efficiency (PCE) and the robust generation of reactive oxygen species (ROS) in the aggregated state is always in high demand but remains a big challenge. Herein, we report a simple strategy to endow molecules with NIR-II imaging and photothermal therapy (PTT)/photodynamic therapy (PDT) abilities by equipping NIR-II aggregation-induced emission luminogens (AIEgens) with the cationic trimethylammonium unit, named as TDTN+. The resultant TDTN+ species can self-assemble into nanoparticles, which exhibit a maximum emission at ∼1052 nm, a high PCE (66.7%), type I and type II ROS generation and a mitochondria-targeting ability, simultaneously. The TDTN+ can realize brain imaging with bright fluorescence and an effective tumor killing effect. Overall, this work presents an innovative design strategy to develop multimodality phototheranostic agents.

Combination of bacterial-targeted delivery of gold-based AIEgen radiosensitizer for fluorescence-image-guided enhanced radio-immunotherapy against advanced cancer.

Aggregation-Induced Emission luminogen (AIEgen) possess great potential in enhancing bioimaging-guided radiotherapeutic effects and radioimmunotherapy to improve the therapeutic effects of the tumor with good biosafety. Bacteria as a natural carrier have demonstrated great advantages in tumor targeted delivery and penetration to tumor. Herein, we construct a delivery platform that Salmonella VNP20009 act as an activated bacteria vector loaded the as-prepared novel AIEgen (TBTP-Au, VNP@TBTP-Au), which showed excellent radio-immunotherapy. VNP@TBTP-Au could target and retain AIEgen at the tumor site and deliver it into tumor cells specially, upon X-ray irradiation, much ROS was generated to induce immunogenic cell death via cGAS-STING signaling pathway to evoke immune response, thus achieving efficient radioimmunotherapy of the primary tumor with good biosafety. More importantly, the radioimmunotherapy with VNP@TBTP-Au formatted good abscopal effect that was able to suppress the growth of distant tumor. Our strategy pioneer a novel and simple strategy for the organic combination of bacteria and imaging-guided radiotherapy, and also pave the foundation for the combination with immunotherapy for better therapeutic effects.

Multifunctional Calcium-Manganese Nanomodulator Provides Antitumor Treatment and Improved Immunotherapy via Reprogramming of the Tumor Microenvironment.

Ions play a vital role in regulating various biological processes, including metabolic and immune homeostasis, which involves tumorigenesis and therapy. Thus, the perturbation of ion homeostasis can induce tumor cell death and evoke immune responses, providing specific antitumor effects. However, antitumor strategies that exploit the effects of multiion perturbation are rare. We herein prepared a pH-responsive nanomodulator by coloading curcumin (CU, a Ca2+ enhancer) with CaCO3 and MnO2 into nanoparticles coated with a cancer cell membrane. This nanoplatform was aimed at reprogramming the tumor microenvironment (TME) and providing an antitumor treatment through ion fluctuation. The obtained nanoplatform, called CM NPs, could neutralize protons by decomposing CaCO3 and attenuating cellular acidity, they could generate Ca2+ and release CU, elevating Ca2+ levels and promoting ROS generation in the mitochondria and endoplasmic reticulum, thus, inducing immunogenic cell death. Mn2+ could decompose the endogenous H2O2 into O2 to relieve hypoxia and enhance the sensitivity of cGAS, activating the cGAS-STING signaling pathway. In addition, this strategy allowed the reprogramming of the immune TME, inducing macrophage polarization and dendritic cell maturation via antigen cross-presentation, thereby increasing the immune system's ability to combat the tumor effectively. Moreover, the as-prepared nanoparticles enhanced the antitumor responses of the αPD1 treatment. This study proposes an effective strategy to combat tumors via the reprogramming of the tumor TME and the alteration of essential ions concentrations. Thus, it shows great potential for future clinical applications as a complementary approach along with other multimodal treatment strategies.

Macrophages in immunoregulation and therapeutics.

Macrophages exist in various tissues, several body cavities, and around mucosal surfaces and are a vital part of the innate immune system for host defense against many pathogens and cancers. Macrophages possess binary M1/M2 macrophage polarization settings, which perform a central role in an array of immune tasks via intrinsic signal cascades and, therefore, must be precisely regulated. Many crucial questions about macrophage signaling and immune modulation are yet to be uncovered. In addition, the clinical importance of tumor-associated macrophages is becoming more widely recognized as significant progress has been made in understanding their biology. Moreover, they are an integral part of the tumor microenvironment, playing a part in the regulation of a wide variety of processes including angiogenesis, extracellular matrix transformation, cancer cell proliferation, metastasis, immunosuppression, and resistance to chemotherapeutic and checkpoint blockade immunotherapies. Herein, we discuss immune regulation in macrophage polarization and signaling, mechanical stresses and modulation, metabolic signaling pathways, mitochondrial and transcriptional, and epigenetic regulation. Furthermore, we have broadly extended the understanding of macrophages in extracellular traps and the essential roles of autophagy and aging in regulating macrophage functions. Moreover, we discussed recent advances in macrophages-mediated immune regulation of autoimmune diseases and tumorigenesis. Lastly, we discussed targeted macrophage therapy to portray prospective targets for therapeutic strategies in health and diseases.

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.

AIEgen-Based Bionic Nanozymes for the Interventional Photodynamic Therapy-Based Treatment of Orthotopic Colon Cancer.

Relative to traditional photosensitizer (PS) agents, those that exhibit aggregation-induced emission (AIE) properties offer key advantages in the context of photodynamic therapy (PDT). At present, PDT efficacy is markedly constrained by the hypoxic microenvironment within tumors and the limited depth to which lasers can penetrate in a therapeutic context. Herein, we developed platelet-mimicking MnO2 nanozyme/AIEgen composites (PMD) for use in the interventional PDT treatment of hypoxic tumors. The resultant biomimetic nanoparticles (NPs) exhibited excellent stability and were able to efficiently target tumors. Moreover, they were able to generate O2 within the tumor microenvironment owing to their catalase-like activity. Notably, through an interventional approach in which an optical fiber was introduced into the abdominal cavity of mice harboring orthotopic colon tumors, good PDT efficacy was achieved. We thus propose that a novel strategy consisting of a combination of an AIEgen-based bionic nanozyme and a biomimetic cell membrane coating represents an ideal therapeutic platform for targeted antitumor PDT. This study is the first to have combined interventional therapy and AIEgen-based PDT, thereby overcoming the limited light penetration that typically constrains the therapeutic efficacy of this technique, highlighting a promising new AIEgen-based PDT treatment strategy.

Dcf1 induces glioblastoma cells apoptosis by blocking autophagy.

BACKGROUND: Dcf1 has been demonstrated to play vital roles in many CNS diseases, it also has a destructive role on cell mitochondria in glioma cells and promotes the autophagy. Hitherto, it is unclear whether the viability of glioblastoma cells is affected by Dcf1, in particular Dcf1 possesses broad localization on different organelles, and the organelles interaction frequently implicated in cancer cells survival. METHODS: Surgically excised WHO grade IV human glioblastoma tissues were collected and cells isolated for culturing. RT-PCR and DNA sequencing assay to estimate the abundance and mutation of Dcf1. iTRAQ sequencing and bioinformatic analysis were performed. Subsequently, immunoprecipitation assay to evaluate the degradation of HistoneH2A isomers by UBA52 ubiquitylation. Transmission electron microscopy (TEM) was applied to observe the structure change of mitochondria and autophagosome. Organelle isolated assay to determine the distribution of protein. Cell cycle and apoptosis were evaluated by flow cytometric assays. RESULTS: Dcf1 was downregulated in WHO grade IV tumor without mutation, and overexpression of Dcf1 was found to significantly regulate glioblastoma cells. One hundred and seventy-six differentially expressed proteins were identified by iTRAQ sequencing. Furthermore, we confirmed that overexpression of Dcf1 destabilized the structure of the nucleosome via UBA52 ubiquitination to downregulate HistoneH2A.X but not macroH2A or HistoneH2A.Z, decreased the mitochondrial DNA copy number and inhibited the mitochondrial biogenesis, thus causing mitochondrial destruction and dysfunction in order to supply cellular energy and induce mitophagy preferentially but not apoptosis. Dcf1 also has disrupted the integrity of lysosomes to block autolysosome degradation and autophagy and to increase the release of Cathepsin B and D from lysosomes into cytosol. These proteins cleaved and activated BID to induce glioblastoma cells apoptosis. CONCLUSIONS: In this study, we demonstrated that unmutated Dcf1 expression is negatively related to the malignancy of glioblastoma, Dcf1 overexpression causes nucleosomes destabilization, mitochondria destruction and dysfunction to induce mitophagy preferentially, and block autophagy by impairing lysosomes to induce apoptosis in glioblastoma.

Light-induced tumor theranostics based on chemical-exfoliated borophene.

Among 2D materials (Xenes) which are at the forefront of research activities, borophene, is an exciting new entry due to its uniquely varied optical, electronic, and chemical properties in many polymorphic forms with widely varying band gaps including the lightest 2D metallic phase. In this paper, we used a simple selective chemical etching to prepare borophene with a strong near IR light-induced photothermal effect. The photothermal efficiency is similar to plasmonic Au nanoparticles, with the added benefit of borophene being degradable due to electron deficiency of boron. We introduce this selective chemical etching process to obtain ultrathin and large borophene nanosheets (thickness of ~4 nm and lateral size up to ~600 nm) from the precursor of AlB2. We also report first-time observation of a selective Acid etching behavior showing HCl etching of Al to form a residual B lattice, while HF selectively etches B to yield an Al lattice. We demonstrate that through surface modification with polydopamine (PDA), a biocompatible smart delivery nanoplatform of B@PDA can respond to a tumor environment, exhibiting an enhanced cellular uptake efficiency. We demonstrate that borophene can be more suitable for safe photothermal theranostic of thick tumor using deep penetrating near IR light compared to gold nanoparticles which are not degradable, thus posing long-term toxicity concerns. With about 40 kinds of borides, we hope that our work will open door to more discoveries of this top-down selective etching approach for generating borophene structures with rich unexplored thermal, electronic, and optical properties for many other technological applications.

Bright Bacterium for Hypoxia-Tolerant Photodynamic Therapy Against Orthotopic Colon Tumors by an Interventional Method.

While promising, the efficacy of aggregation-induced emission (AIE)-based photodynamic therapy (PDT) is limited by several factors including limited depth of laser penetration and intratumoral hypoxia. In the present study, a novel bacteria-based AIEgen (TBP-2) hybrid system (AE) is developed, that is able to facilitate the hypoxia-tolerant PDT treatment of orthotopic colon tumors via an interventional method. For this approach, an interventional device is initially designed, composed of an optical fiber and an endoscope, allowing for clear visualization of the position of the orthotopic tumor within the abdominal cavity. It is then possible to conduct successful PDT treatment of this hypoxic tumor via laser irradiation, as the TBP-2 is able to generate hydroxyl radicals (•OH) via a type I mechanism within this hypoxic microenvironment. Moreover, this interventional approach is proved to significantly impair orthotopic colon cancer growth and overcame PDT defects. This study is the first report involving such an interventional PDT strategy to knowledge, and it has the potential to complement other treatment modalities while also highlighting novel approaches to the design of hybrid AIEgen systems.

Patient-derived microvesicles/AIE luminogen hybrid system for personalized sonodynamic cancer therapy in patient-derived xenograft models.

Sonodynamic therapy (SDT), as an efficient way of tumor treatment, has the advantages of deep tumor penetration and high therapeutic efficacy. However, developing efficient sonosensitizers are still challenging. AIEgen-based SDT is rarely reported and it is urgent to develop novel AIEgen-active sonosensitizers. Furthermore, the AIEgen-based theranostic system is promisingly needed to be proved on PDX models to be closer to the clinic. Herein, we constructed a novel AIEgen based SDT system and found that DCPy has advantages over traditional sonosensitizers in SDT. Then, a patient-derived MVs/AIEgen hybrid system (AMVs) prepared by electroporation was used for personalized SDT in bladder cancer patient-derived xenograft (PDX) models. Impressively, AMVs displayed the superior tumor targeting ability and efficient personalized SDT therapy on PDX models, both of which were much more improved compared with PLGA/AIEgens nanoparticles and cell line-derived micro vesicles. This work provides new ideas for both the design of AIE-active sonosensitizers and the SDT treatment of cancers, further expanding the potential clinical application of AIEgens in the future.

Development of MOF "Armor-Plated" Phycocyanin and Synergistic Inhibition of Cellular Respiration for Hypoxic Photodynamic Therapy in Patient-Derived Xenograft Models.

Significant progress has been made in the use of phycocyanin (PC) as a photosensitizer (PS) agent for photodynamic therapy (PDT). The clinical use of PC, however, has been limited by its poor stability, unfavorable pharmacokinetics, limited tumor cell uptake, and the hypoxic nature of the tumor microenvironment. In this study, a novel biomimetic mineralization approach is described for encapsulating PC using zeolitic imidazolate framework-8 (ZIF-8), after which MPEG2000 -COOH is further utilized as an anchor on the ZIF/PC complex in order to yield MPEG2000 -ZIF/PC composites (PMs). These PMs are then used as a stable reinforced PS for PDT, effectively improving the intracellular delivery of this protein PS. In contrast to prior studies that have sought to overcome intratumoral hypoxia via increasing oxygen delivery to the tumor site, the mitochondrial complex I inhibitor papaverine (PPV) is instead utilized to reduce intratumor oxygen consumption in an effort to augment the PDT efficacy of the PMs. It is found that this combination treatment strategy markedly improves the antitumor properties of these PMs both in vitro and in patient-derived xenograft (PDX) models without inducing significant side effects. It is therefore proposed that the "armor-plating" of protein PS agents with ZIF-8 in combination with PPV may be a promising approach to precision medicine-mediated tumor treatment.

Off-tumor IDO1 target engagements determine the cancer-immune set point and predict the immunotherapeutic efficacy.

BACKGROUND: Indoleamine-2,3-dioxygenase 1 (IDO1) has been intensively pursued as a therapeutic target to reverse the immunosuppressive cancer-immune milieu and promote tumor elimination. However, recent failures of phase III clinical trials with IDO1 inhibitors involved in cancer immunotherapies highlight the urgent need to develop appropriate methods for tracking IDO1 when the cancer-immune milieu is therapeutically modified. METHODS: We utilized a small-molecule radiotracer, 11C-l-1MTrp, to quantitatively and longitudinally visualize whole-body IDO1 dynamics. Specifically, we first assessed 11C-l-1MTrp in mice-bearing contralateral human tumors with distinct IDO1 expression patterns. Then, we applied 11C-l-1MTrp to longitudinally monitor whole-body IDO1 variations in immunocompetent melanoma-bearing mice treated with 1-methyl-l-tryptophan plus either chemotherapeutic drugs or antibodies targeting programmedcell death 1 and cytotoxic T-lymphocyte-associated protein 4. RESULTS: 11C-l-1MTrp positron emission tomography (PET) imaging accurately delineated IDO1 expression in xenograft mouse models. Moreover, we were able to visualize dynamic IDO1 regulation in the mesenteric lymph nodes (MLNs), an off-tumor IDO1 target, where the percentage uptake of 11C-l-1MTrp accurately annotated the therapeutic efficacy of multiple combination immunotherapies in preclinical models. Remarkably, 11C-l-1MTrp signal intensity in the MLNs was inversely related to the specific growth rates of treated tumors, suggesting that IDO1 expression in the MLNs can serve as a new biomarker of the cancer-immune set point. CONCLUSIONS: PET imaging of IDO1 with 11C-l-1MTrp is a robust method to assess the therapeutic efficacy of multiple combinatorial immunotherapies, improving our understanding of the merit and challenges of IDO1 regimens. Further validation of this animal data in humans is ongoing. We envision that our results will provide a potential precision medicine paradigm for noninvasive visualizing each patient's individual response in combinatorial cancer immunotherapy, and tailoring optimal personalized combination strategies.