Cancer cell-specific and pro-apoptotic SMAC peptide-doxorubicin conjugated prodrug encapsulated aposomes for synergistic cancer immunotherapy.

BACKGROUND: Immunogenic cell death (ICD) is a crucial approach to turn immunosuppressive tumor microenvironment (ITM) into immune-responsive milieu and improve the response rate of immune checkpoint blockade (ICB) therapy. However, cancer cells show resistance to ICD-inducing chemotherapeutic drugs, and non-specific toxicity of those drugs against immune cells reduce the immunotherapy efficiency. METHODS: Herein, we propose cancer cell-specific and pro-apoptotic liposomes (Aposomes) encapsulating second mitochondria-derived activator of caspases mimetic peptide (SMAC-P)-doxorubicin (DOX) conjugated prodrug to potentiate combinational ICB therapy with ICD. The SMAC-P (AVPIAQ) with cathepsin B-cleavable peptide (FRRG) was directly conjugated to DOX, and the resulting SMAC-P-FRRG-DOX prodrug was encapsulated into PEGylated liposomes. RESULTS: The SMAC-P-FRRG-DOX encapsulated PEGylated liposomes (Aposomes) form a stable nanostructure with an average diameter of 109.1 ± 5.14 nm and promote the apoptotic cell death mainly in cathepsin B-overexpressed cancer cells. Therefore, Aposomes induce a potent ICD in targeted cancer cells in synergy of SMAC-P with DOX in cultured cells. In colon tumor models, Aposomes efficiently accumulate in targeted tumor tissues via enhanced permeability and retention (EPR) effect and release the encapsulated prodrug of SMAC-P-FRRG-DOX, which is subsequently cleaved to SMAC-P and DOX in cancer cells. Importantly, the synergistic activity of inhibitors of apoptosis proteins (IAPs)-inhibitory SMAC-P sensitizing the effects of DOX induces a potent ICD in the cancer cells to promote dendritic cell (DC) maturation and stimulate T cell proliferation and activation, turning ITM into immune-responsive milieu. CONCLUSIONS: Eventually, the combination of Aposomes with anti-PD-L1 antibody results in a high rate of complete tumor regression (CR: 80%) and also prevent the tumor recurrence by immunological memory established during treatments.

Multi-functional nanomedicines for combinational cancer immunotherapy that transform cold tumors to hot tumors.

INTRODUCTION: Currently, cancer immunotherapy is widely used as a groundbreaking method that can completely cure advanced cancers. However, this new immunotherapy has the challenge of low patient response, which is often due to many patients' tumors having an immunosuppressive environment, known as cold tumors. AREAS COVERED: This review aims to introduce various nanomedicine-derived combinational cancer immunotherapy that can transform cold tumor into hot tumors. Initially, we discuss new technologies for combinational immunotherapy based on multifunctional nanomedicines that can deliver combinational immunogenic cell death (ICD) inducers, immune checkpoint blockades (ICBs) and immune modulators (IMs) to targeted tumor tissues at the same time. Ultimately, we highlight how multifunctional nanomedicines for combinational cancer immunotherapy can be used to transform cold tumor into hot tumors against advanced cancers. EXPERT OPINION: Nanomedicine-derived combinational cancer immunotherapy for delivering multiple ICD inducers, ICBs, and IMs at the same time is recognized as a new potential technology that can activate tumor immunity and simultaneously increase the therapeutic efficacy of immune cells that can transform effectively the cold tumors into hot tumors. Finally, nanomedicine-derived combinational cancer immunotherapy can solve the serious problems of low therapeutic efficacy that occurs when treating single drug or simple combinational drugs in cancer immunotherapy.

Nano-Delivery of Immunogenic Cell Death Inducers and Immune Checkpoint Blockade Agents: Single-Nanostructure Strategies for Enhancing Immunotherapy.

Cancer immunotherapy has revolutionized oncology by harnessing the patient's immune system to target and eliminate cancer cells. However, immune checkpoint blockades (ICBs) face limitations such as low response rates, particularly in immunologically 'cold' tumors. Enhancing tumor immunogenicity through immunogenic cell death (ICD) inducers and advanced drug delivery systems represents a promising solution. This review discusses the development and application of various nanocarriers, including polymeric nanoparticles, liposomes, peptide-based nanoparticles, and inorganic nanoparticles, designed to deliver ICD inducers and ICBs effectively. These nanocarriers improve therapeutic outcomes by converting cold tumors into hot tumors, thus enhancing immune responses and reducing systemic toxicity. By focusing on single-nanoparticle systems that co-deliver both ICD inducers and ICBs, this review highlights their potential in achieving higher drug concentrations at tumor sites, improving pharmacokinetics and pharmacodynamics, and facilitating clinical translation. Future research should aim to optimize these nanocarrier systems for better in vivo performance and clinical applications, ultimately advancing cancer immunotherapy.

Photo-induced crosslinked and anti-PD-L1 peptide incorporated liposomes to promote PD-L1 multivalent binding for effective immune checkpoint blockade therapy.

Immune checkpoint blockade (ICB) therapy targeting PD-L1 via monoclonal antibody (mAb) has shown extensive clinical benefits in the diverse types of advanced malignancies. However, most patients are completely refractory to ICB therapy owing to the PD-L1 recycling mechanism. Herein, we propose photo-induced crosslinked and anti-PD-L1 peptide incorporated liposomes (immune checkpoint blockade liposomes; ICB-LPs) to promote PD-L1 multivalent binding for inducing lysosomal degradation of PD-L1 in tumor cells. The ICB-LPs are prepared by formulation of DC8,9PC with photo-polymerized diacetylenic moiety, 1,2-dipalmitoylphosphatidylcholine (DPPC) and anti-PD-L1 peptide (D-form NYSKPTDRQYHF)-conjugated DSPE-PEG2k (anti-PD-L1-DSPE-PEG2k) in a molar ratio of 45:45:10, followed by cross-linking of liposomal bilayer upon UV irradiation. The 10 mol% anti-PD-L1-DSPE-PEG2k incorporated ICB-LPs have a nano-sized lipid bilayer structure with an average diameter of 137.7 ± 1.04 nm, showing a high stability in serum condition. Importantly, the ICB-LPs efficiently promote the multivalent binding with PD-L1 on the tumor cell membrane, which are endocytosed with aim to deliver PD-L1 to the lysosomes, wherein the durable PD-L1 degradation is observed for 72 h, in contrast to anti PD-L1 mAbs showing the rapid PD-L1 recycling within 9 h. The in vitro co-culture experiments with CD8+ T cells show that ICB-LPs effectively enhance the T cell-mediated antitumor immune responses against tumor cells by blocking the PD-L1/PD-1 axis. When ICB-LPs are intravenously injected into colon tumor-bearing mice, they efficiently accumulate within the targeted tumor tissues via both passive and active tumor targeting, inducing a potent T cell-mediated antitumor immune response by effective and durable PD-L1 degradation. Collectively, this study demonstrates the superior antitumor efficacy of crosslinked and anti-PD-L1 peptide incorporated liposome formulation that promotes PD-L1 multivalent binding for trafficking of PD-L1 toward the lysosomes instead of the recycling endosomes.

Accurately Controlled Tumor Temperature with Silica-Coated Gold Nanorods for Optimal Immune Checkpoint Blockade Therapy.

Photothermal therapy (PTT) at mild temperatures ranging from 44 to 45 °C holds tremendous promise as a strategy for inducing potent immunogenic cell death (ICD) within tumor tissues, which can reverse the immunosuppressive tumor microenvironment (ITM) into an immune-responsive milieu. However, accurately and precisely controlling the tumor temperature remains a formidable challenge. Here, we report the precision photothermal immunotherapy by using silica-coated gold nanorods (AuNR@SiO2), and investigating the optimal administration routes and treatment protocols, which enabled to achieve the sustained and controlled mild heating within the tumor tissues. First, the highest photothermal performance of AuNR@SiO2 with 20-nm silica shell thickness than 5 or 40 nm was confirmed in vitro and in vivo. Then, the optimal conditions for precision immunotherapy were further investigated to produce mild temperature (44 to 45 °C) accurately in tumor tissues. The optimal conditions with AuNR@SiO2 result in a distinct cell death with high early/late apoptosis and low necrosis, leading to very efficient ICD compared to lower or higher temperatures. In colon tumor-bearing mice, intratumorally injected AuNR@SiO2 efficiently promotes a mild temperature within the tumor tissues by local irradiation of near-infrared (NIR) laser. This mild PTT substantially increases the population of mature dendritic cells (DCs) and cytotoxic T cells (CTLs) within tumor tissues, ultimately reversing the ITM into an immune-responsive milieu. Furthermore, we found that the combination mild PTT with AuNR@SiO2 and anti-PD-L1 therapy could lead to the 100% complete regression of primary tumors and immunological memory to prevent tumor recurrence. Collectively, this study demonstrates that AuNR@SiO2 with a robust methodology capable of continuously inducing mild temperature accurately within the ITM holds promise as an approach to achieve the precision photothermal immunotherapy.

Light-Triggered PROTAC Nanoassemblies for Photodynamic IDO Proteolysis in Cancer Immunotherapy.

While proteolysis-targeting chimeras (PROTACs) hold great potential for persistently reprogramming the immunosuppressive tumor microenvironment via targeted protein degradation, precisely activating them in tumor tissues and preventing uncontrolled proteolysis at off-target sites remain challenging. Herein, a light-triggered PROTAC nanoassembly (LPN) for photodynamic indoleamine 2,3-dioxygenase (IDO) proteolysis is reported. The LPN is derived from the self-assembly of prodrug conjugates, which comprise a PROTAC, cathepsin B-specific cleavable peptide linker, and photosensitizer, without any additional carrier materials. In colon tumor models, intravenously injected LPNs initially silence the activity of PROTACs and accumulate significantly in targeted tumor tissues due to an enhanced permeability and retention effect. Subsequently, the cancer biomarker cathepsin B begins to trigger the release of active PROTACs from the LPNs through enzymatic cleavage of the linkers. Upon light irradiation, tumor cells undergo immunogenic cell death induced by photodynamic therapy to promote the activation of effector T cells, while the continuous IDO degradation of PROTAC simultaneously blocks tryptophan metabolite-regulated regulatory-T-cell-mediated immunosuppression. Such LPN-mediated combinatorial photodynamic IDO proteolysis effectively inhibits tumor growth, metastasis, and recurrence. Collectively, this study presents a promising nanomedicine, designed to synergize PROTACs with other immunotherapeutic modalities, for more effective and safer cancer immunotherapy.

Mucoadhesive Mesalamine Prodrug Nanoassemblies to Target Intestinal Macrophages for the Treatment of Inflammatory Bowel Disease.

While mesalamine, a 5-aminosalicylic acid (5-ASA), is pivotal in the management of inflammatory bowel disease (IBD) through both step-up and top-down approaches in clinical settings, its widespread utilization is limited by low bioavailability at the desired site of action due to rapid and extensive absorption in the upper gastrointestinal (GI) tract. Addressing mesalamine's pharmacokinetic challenges, here, we introduce nanoassemblies composed exclusively of a mesalamine prodrug that pairs 5-ASA with a mucoadhesive and cathepsin B-cleavable peptide. In an IBD model, orally administered nanoassemblies demonstrate enhanced accumulation and sustained retention in the GI tract due to their mucoadhesive properties and the epithelial enhanced permeability and retention (eEPR) effect. This retention enables the efficient uptake by intestinal pro-inflammatory macrophages expressing high cathepsin B, triggering a burst release of the 5-ASA. This cascade fosters the polarization toward an M2 macrophage phenotype, diminishes inflammatory responses, and simultaneously facilitates the delivery of active agents to adjacent epithelial cells. Therefore, the nanoassemblies show outstanding therapeutic efficacy in inhibiting local inflammation and contribute to suppressing systemic inflammation by restoring damaged intestinal barriers. Collectively, this study highlights the promising role of the prodrug nanoassemblies in enhancing targeted drug delivery, potentially broadening the use of mesalamine in managing IBD.

Fluorescence-Based Mono- and Multimodal Imaging for In Vivo Tracking of Mesenchymal Stem Cells.

The advancement of stem cell therapy has offered transformative therapeutic outcomes for a wide array of diseases over the past decades. Consequently, stem cell tracking has become significant in revealing the mechanisms of action and ensuring safe and effective treatments. Fluorescence stands out as a promising choice for stem cell tracking due to its myriad advantages, including high resolution, real-time monitoring, and multi-fluorescence detection. Furthermore, combining fluorescence with other tracking modalities-such as bioluminescence imaging (BLI), positron emission tomography (PET), photoacoustic (PA), computed tomography (CT), and magnetic resonance (MR)-can address the limitations of single fluorescence detection. This review initially introduces stem cell tracking using fluorescence imaging, detailing various labeling strategies such as green fluorescence protein (GFP) tagging, fluorescence dye labeling, and nanoparticle uptake. Subsequently, we present several combinations of strategies for efficient and precise detection.