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.

Design of PD-L1-Targeted Lipid Nanoparticles to Turn on PTEN for Efficient Cancer Therapy.

Lipid nanoparticles (LNPs) exhibit remarkable mRNA delivery efficiency, yet their majority accumulate in the liver or spleen after injection. Tissue-specific mRNA delivery can be achieved through modulating LNP properties, such as tuning PEGylation or varying lipid components systematically. In this paper, a streamlined method is used for incorporating tumor-targeting peptides into the LNPs; the programmed death ligand 1 (PD-L1) binding peptides are conjugated to PEGylated lipids via a copper-free click reaction, and directly incorporated into the LNP composition (Pep LNPs). Notably, Pep LNPs display robust interaction with PD-L1 proteins, which leads to the uptake of LNPs into PD-L1 overexpressing cancer cells both in vitro and in vivo. To evaluate anticancer immunotherapy mediated by restoring tumor suppressor, mRNA encoding phosphatase and tensin homolog (PTEN) is delivered via Pep LNPs to PTEN-deficient triple-negative breast cancers (TNBCs). Pep LNPs loaded with PTEN mRNA specifically promotes autophagy-mediated immunogenic cell death in 4T1 tumors, resulting in effective anticancer immune responses. This study highlights the potential of tumor-targeted LNPs for mRNA-based cancer therapy.

Oral TNF-α siRNA delivery via milk-derived exosomes for effective treatment of inflammatory bowel disease.

Oral administration facilitates the direct delivery of drugs to lesions within the small intestine and colon, making it an ideal approach for treating patients with inflammatory bowel disease. However, multiple physical barriers impede the delivery of oral RNA drugs through the gastrointestinal tract. Herein, we developed a novel oral siRNA delivery system that protects nucleic acids in extreme environments by employing exosomes derived from milk to encapsulate tumor necrosis factor-alpha (TNF-α) siRNA completely. The remarkable structural stability of milk-derived exosomes (M-Exos), as opposed to those from HEK293T cells, makes them exceptional siRNA carriers. Results demonstrate that milk exosomes loaded with TNF-α siRNA (M-Exo/siR) can effectively inhibit the expression of TNF-α-related inflammatory cytokines. Moreover, given that milk exosomes are composed of unique lipids with high bioavailability, orally administered M-Exo/siR effectively reach colonic tissues, leading to decreased TNF-α expression and successful alleviation of colitis symptoms in a dextran sulfate sodium-induced inflammatory bowel disease murine model. Hence, milk-derived exosomes carrying TNF-α siRNA can be effectively employed to treat inflammatory bowel disease. Indeed, using exosomes naturally derived from milk may shift the current paradigm of oral gene delivery, including siRNA.

Post-insertion technique to introduce targeting moieties in milk exosomes for targeted drug delivery.

BACKGROUND: Recently, increased attention has been given on exosomes as ideal nanocarriers of drugs owing to their intrinsic properties that facilitate the transport of biomolecular cargos. However, large-scale exosome production remains a major challenge in the clinical application of exosome-based drug delivery systems. Considering its biocompatibility and stability, bovine milk is a suitable natural source for large-scale and stable exosome production. Because the active-targeting ability of drug carriers is essential to maximize therapeutic efficacy and minimize side effects, precise membrane functionalization strategies are required to enable tissue-specific delivery of milk exosomes with difficulty in post-isolation modification. METHODS: In this study, the membrane functionalization of a milk exosome platform modified using a simple post-insertion method was examined comprehensively. Exosomes were engineered from bovine milk (mExo) with surface-tunable modifications for the delivery of tumor-targeting doxorubicin (Dox). The surface modification of mExo was achieved through the hydrophobic insertion of folate (FA)-conjugated lipids. RESULTS: We have confirmed the stable integration of functionalized PE-lipid chains into the mExo membrane through an optimized post-insertion technique, thereby effectively enhancing the surface functionality of mExo. Indeed, the results revealed that FA-modified mExo (mExo-FA) improved cellular uptake in cancer cells via FA receptor (FR)-mediated endocytosis. The designed mExo-FA selectively delivered Dox to FR-positive tumor cells and triggered notable tumor cell death, as confirmed by in vitro and in vivo analyses. CONCLUSIONS: This simple and easy method for post-isolation modification of the exosomal surface may be used to develop milk-exosome-based drug delivery systems.

Design of siRNA Bioconjugates for Efficient Control of Cancer-Associated Membrane Receptors.

Research on siRNA delivery has seen tremendous growth over the past few decades. As one of the major delivery strategies, siRNA bioconjugates offer the potential to enhance and extend the pharmacological properties of siRNAs while minimizing toxicity. In this paper, we suggest the development of a siRNA conjugate platform with peptides and proteins that are ligands of target receptors for cancer treatment. The siRNA bioconjugates target and block the receptor membrane proteins, enter the cells through receptor-mediated endocytosis, and inhibit the expression of that same target membrane receptor, thereby doubly controlling the function of the membrane proteins. The three kinds of bioconjugates targeting CD47, PD-L1, and EGFR were synthesized via two different copper-free click chemistry reactions. Results showed the cellular uptake of each conjugate, reduction of target gene expression, and efficient functional control of receptor proteins. This platform provides an effective approach for regulating membrane proteins in various diseases beyond cancer.

mRNA: A promising platform for cancer immunotherapy.

Messenger RNA (mRNA) is now in the limelight as a powerful tool for treating various human diseases, especially malignant tumors, thanks to the remarkable clinical outcomes of mRNA vaccines using lipid nanoparticle technology during the COVID-19 pandemic. Recent promising preclinical and clinical results that epitomize the advancement in mRNA and nanoformulation-based delivery technologies have highlighted the tremendous potential of mRNA in cancer immunotherapy. mRNAs can be harnessed for cancer immunotherapy in forms of various therapeutic modalities, including cancer vaccines, adoptive T-cell therapies, therapeutic antibodies, and immunomodulatory proteins. This review provides a comprehensive overview of the current state and prospects of mRNA-based therapeutics, including numerous delivery and therapeutic strategies.

Harnessing Oncolytic Extracellular Vesicles for Tumor Cell-Preferential Cytoplasmic Delivery of Misfolded Proteins for Cancer Immunotherapy.

In this study, extracellular vesicles (EVs) are reimagined as more than just a cellular waste disposal system and are repurposed for cancer immunotherapy. Potent oncolytic EVs (bRSVF-EVs) loaded with misfolded proteins (MPs) are engineered, which are typically considered cellular debris. By impairing lysosomal function using bafilomycin A1 and expressing the respiratory syncytial virus F protein, a viral fusogen, MPs are successfully loaded into the EVs expressing RSVF. bRSVF-EVs preferentially transplant a xenogeneic antigen onto cancer cell membranes in a nucleolin-dependent manner, triggering an innate immune response. Furthermore, bRSVF-EV-mediated direct delivery of MPs into the cancer cell cytoplasm initiates endoplasmic reticulum stress and immunogenic cell death (ICD). This mechanism of action leads to substantial antitumor immune responses in murine tumor models. Importantly, when combined with PD-1 blockade, bRSVF-EV treatment elicits robust antitumor immunity, resulting in prolonged survival and complete remission in some cases. Overall, the findings demonstrate that utilizing tumor-targeting oncolytic EVs for direct cytoplasmic delivery of MPs to induce ICD in cancer cells represents a promising approach for enhancing durable antitumor immunity.

Immune checkpoint-targeted drug conjugates: A promising tool for remodeling tumor immune microenvironment.

Immune checkpoint blockade (ICB) therapy has shown remarkable outcomes along with multiple cases of complete regression in clinical practice. But unfortunately, most patients who have an immunosuppressive tumor immune microenvironment (TIME) respond poorly to these therapies. To improve the response rate of the patients, various treatment modalities that can boost cancer immunogenicity and remove immune tolerance have been combined with ICB therapies. However, the systemic administration of multiple immunotherapeutic agents can potentially cause severe off-target toxicities and immune-related adverse events, diminishing antitumor immunity and increasing the risk of additional complications. To address these problems, Immune Checkpoint-Targeted Drug Conjugates (IDCs) have been widely investigated for their ability to offer distinct advantages in remodeling the TIME for cancer immunotherapy. IDCs, consisting of immune checkpoint-targeting moieties, cleavable linkers, and payloads of immunotherapeutic agents, have a similar structure to conventional antibody-drug conjugates (ADCs) but target and block the immune checkpoint receptors, and then release the payloads conjugated through cleavable linkers. These unique mechanisms of IDCs prompt an immune-responsive TIME by modulating the multiple steps related to the cancer-immunity cycle, ultimately leading to tumor eradication. This review outlines the mode of action and advantages of IDCs. In addition, various IDCs for combinational immunotherapy are reviewed. Finally, the potential and challenges of IDCs for clinical translation are discussed.

Exosome-guided direct reprogramming of tumor-associated macrophages from protumorigenic to antitumorigenic to fight cancer.

Highly immunosuppressive tumor microenvironment containing various protumoral immune cells accelerates malignant transformation and treatment resistance. In particular, tumor-associated macrophages (TAMs), as the predominant infiltrated immune cells in a tumor, play a pivotal role in regulating the immunosuppressive tumor microenvironment. As a potential therapeutic strategy to counteract TAMs, here we explore an exosome-guided in situ direct reprogramming of tumor-supportive M2-polarized TAMs into tumor-attacking M1-type macrophages. Exosomes derived from M1-type macrophages (M1-Exo) promote a phenotypic switch from anti-inflammatory M2-like TAMs toward pro-inflammatory M1-type macrophages with high conversion efficiency. Reprogrammed M1 macrophages possessing protein-expression profiles similar to those of classically activated M1 macrophages display significantly increased phagocytic function and robust cross-presentation ability, potentiating antitumor immunity surrounding the tumor. Strikingly, these M1-Exo also lead to the conversion of human patient-derived TAMs into M1-like macrophages that highly express MHC class II, offering the clinical potential of autologous and allogeneic exosome-guided direct TAM reprogramming for arming macrophages to join the fight against cancer.

Molecularly engineered siRNA conjugates for tumor-targeted RNAi therapy.

RNA interference (RNAi) is a major cellular mechanism regulating gene expression in which short double-stranded RNA molecules called small interfering RNA (siRNA) mediate sequence-specific mRNA degradation. RNAi technology has recently emerged as a promising therapeutic platform for the effective treatment of various diseases caused by inappropriate gene activity, such as cancer. However, the clinical translation of siRNA therapeutics has been hampered by the major hurdles associated with biological instability and limited delivery efficiency. Based on the various efforts, recent siRNA delivery strategies using cationic lipids and polymers allowed to enhance pharmacokinetics and delivery efficiency, resulting in potent and liver-targeted RNAi therapy. However, non-specific protein adsorption, high liver accumulation, and severe toxicity of cationic nanocarriers still limit the possibility of transfer of siRNA therapeutics from the laboratory to the clinic. One of the promising delivery strategies to overcome the limitations of siRNA therapeutics is carrier-free bioconjugation which is chemically modified and connected with biocompatible molecules such as lipids, peptides, antibodies, aptamers, and polymers. These molecularly engineered siRNA conjugates can be utilized for RNAi delivery to tissues beyond the liver, providing opportunities for clinical translation. This review focused on introducing the recent progress in molecularly engineered siRNA conjugates and their applications toward overcoming the limitations of siRNA for tumor-targeted delivery and therapy.

The Potential of Cell-Penetrating Peptides for mRNA Delivery to Cancer Cells.

In vitro transcribed mRNA for the synthesis of any given protein has shown great potential in cancer gene therapy, especially in cancer vaccines for immunotherapy. To overcome physiological barriers, such as rapid degradation by enzymatic attack and poor cellular uptake due to their large size and hydrophilic properties, many delivery carriers for mRNAs are being investigated for improving the bioavailability of mRNA. Recently, cell-penetrating peptides (CPPs) have received attention as promising tools for gene delivery. In terms of their biocompatibility and the ability to target specific cells with the versatility of peptide sequences, they may provide clues to address the challenges of conventional delivery systems for cancer mRNA delivery. In this study, optimal conditions for the CPP/mRNA complexes were identified in terms of complexation capacity and N/P ratio, and protection against RNase was confirmed. When cancer cells were treated at a concentration of 6.8 nM, which could deliver the highest amount of mRNA without toxicity, the amphipathic CPP/mRNA complexes with a size less than 200 nm showed high cellular uptake and protein expression. With advances in our understanding of CPPs, CPPs designed to target tumor tissues will be promising for use in developing a new class of mRNA delivery vehicles in cancer therapy.

Extracellular vesicle-guided in situ reprogramming of synovial macrophages for the treatment of rheumatoid arthritis.

Activation state of synovial macrophages is significantly correlated with disease activity and severity of rheumatoid arthritis (RA) and provides valuable clues for RA treatment. Classically activated M1 macrophages in inflamed synovial joints secrete high levels of pro-inflammatory cytokines and chemokines, resulting in bone erosion and cartilage degradation. Herein, we propose extracellular vesicle (EV)-guided in situ macrophage reprogramming toward anti-inflammatory M2 macrophages as a novel RA treatment modality based on the immunotherapeutic concept of reestablishing M1-M2 macrophage equilibrium in synovial tissue. M2 macrophage-derived EVs (M2-EVs) were able to convert activated M1 into reprogrammed M2 (RM2) macrophages with extremely high efficiency (>90%), producing a distinct protein expression pattern characteristic of anti-inflammatory M2 macrophages. In particular, M2-EVs were enriched for proteins known to be involved in the generation and migration of M2 macrophages as well as macrophage reprogramming factors, allowing for rapid and efficient driving of macrophage polarization toward M2 phenotype. After administration of M2-EVs into the joint of a collagen-induced arthritis mouse model, the synovial macrophage polarization was significantly shifted from M1 to M2 phenotype, a process that benefited greatly from the long residence time (>3 days) of M2-EVs in the joint. This superb in situ macrophage-reprogramming ability of EVs resulted in decreased joint swelling, arthritic index score and synovial inflammation, with corresponding reductions in bone erosion and articular cartilage damage and no systemic toxicity. The anti-RA effects of M2-EVs were comparable to those of the conventional disease-modifying antirheumatic drug, Methotrexate, which causes a range of toxic adverse effects, including gastrointestinal mucosal injury. Overall, our EV-guided reprogramming strategy for in situ tuning of macrophage responses holds great promise for the development of anti-inflammatory therapeutics for the treatment of various inflammatory diseases in addition to RA.

PDL1-binding peptide/anti-miRNA21 conjugate as a therapeutic modality for PD-L1high tumors and TAMs.

Upregulation of oncogenic miRNA21 (miR-21) plays a pivotal role in proliferation, migration and invasion of cancer cells. In addition to cancer cells, tumor-associated macrophages (TAMs) also have high abundance of miR-21, which accelerates malignant progression of tumors in the late stages of carcinogenesis. Despite of the pro-tumorigenic functions of miR-21 in TAMs and cancer cells, reliable therapeutic strategies to simultaneously inhibit miR-21 activity in both types of cell have not yet been developed. In this study, we designed a dual-targeting drug delivery system of miR-21 inhibitors that could bind to both tumor cells and macrophages with overexpressed PD-L1 receptors. This peptide-oligonucleotide conjugate (Pep-21) consists of a PDL1-binding peptide covalently linked with an anti-miR-21 inhibitor via click chemistry. Pep-21 was preferentially internalized in both cell types, consequently depleting endogenous miR-21. Our studies found that Pep-21 treatment reduced tumor cell migration, reprogrammed immunosuppressive M2-type TAMs into M1-type macrophages, and restrained tumor progression. Collectively, neutralization of miR-21 activity in both cancer cells and TAMs can be a promising strategy for effective antitumor responses.

Sustained Exosome-Guided Macrophage Polarization Using Hydrolytically Degradable PEG Hydrogels for Cutaneous Wound Healing: Identification of Key Proteins and MiRNAs, and Sustained Release Formulation.

Macrophages (Mφs) are characterized by remarkable plasticity, an essential component of chronic inflammation. Thus, an appropriate and timely transition from proinflammatory (M1) to anti-inflammatory (M2) Mφs during wound healing is vital to promoting resolution of acute inflammation and enhancing tissue repair. Herein, exosomes derived from M2-Mφs (M2-Exos), which contain putative key regulators driving Mφ polarization, are used as local microenvironmental cues to induce reprogramming of M1-Mφs toward M2-Mφs for effective wound management. As an injectable controlled release depot for exosomes, hydrolytically degradable poly(ethylene glycol) (PEG) hydrogels (Exogels) are designed and employed for encapsulating M2-Exos to maximize their therapeutic effects in cutaneous wound healing. The degradation time of the hydrogels is adjustable from 6 days or up to 27 days by controlling the crosslinking density and tightness. The localization of M2-Exos leads to a successful local transition from M1-Mφs to M2-Mφs within the lesion for more than 6 days, followed by enhanced therapeutic effects including rapid wound closure and increased healing quality in an animal model for cutaneous wound healing. Collectively, the hydrolytically degradable PEG hydrogel-based exosome delivery system may serve as a potential tool in regulating local polarization state of Mφs, which is crucial for tissue homeostasis and wound repair.

Ultraefficient extracellular vesicle-guided direct reprogramming of fibroblasts into functional cardiomyocytes.

Direct lineage conversion holds great promise in the regenerative medicine field for restoring damaged tissues using functionally engineered counterparts. However, current methods of direct lineage conversion, even those using virus-mediated transgenic expression of tumorigenic factors, are extremely inefficient (~25%). Thus, advanced methodologies capable of revolutionizing efficiency and addressing safety concerns are key to clinical translation of these technologies. Here, we propose an extracellular vesicle (EV)-guided, nonviral, direct lineage conversion strategy to enhance transdifferentiation of fibroblasts to induced cardiomyocyte-like cells (iCMs). The resulting iCMs have typical cardiac Ca2+ transients and electrophysiological features and exhibit global gene expression profiles similar to those of cardiomyocytes. This is the first demonstration of the use of EVs derived from embryonic stem cells undergoing cardiac differentiation as biomimetic tools to induce cardiac reprogramming with extremely high efficiency (>60%), establishing a general, more readily accessible platform for generating a variety of specialized somatic cells through direct lineage conversion.

Nanoparticles Targeting Innate Immune Cells in Tumor Microenvironment.

A variety of innate immune cells such as macrophages, dendritic cells, myeloid-derived suppressor cells, natural killer cells, and neutrophils in the tumor microenvironments, contribute to tumor progression. However, while several recent reports have studied the use of immune checkpoint-based cancer immunotherapy, little work has focused on modulating the innate immune cells. This review focuses on the recent studies and challenges of using nanoparticles to target innate immune cells. In particular, we also examine the immunosuppressive properties of certain innate immune cells that limit clinical benefits. Understanding the cross-talk between tumors and innate immune cells could contribute to the development of strategies for manipulating the nanoparticles targeting tumor microenvironments.

Recent Advances in Exosome-Based Drug Delivery for Cancer Therapy.

Exosomes are a class of extracellular vesicles, with a size of about 100 nm, secreted by most cells and carrying various bioactive molecules such as nucleic acids, proteins, and lipids, and reflect the biological status of parent cells. Exosomes have natural advantages such as high biocompatibility and low immunogenicity for efficient delivery of therapeutic agents such as chemotherapeutic drugs, nucleic acids, and proteins. In this review, we introduce the latest explorations of exosome-based drug delivery systems for cancer therapy, with particular focus on the targeted delivery of various types of cargoes.

A Trojan-Horse Strategy by In Situ Piggybacking onto Endogenous Albumin for Tumor-Specific Neutralization of Oncogenic MicroRNA.

MicroRNAs (miRNAs), a recently discovered class of noncoding RNAs, play pivotal roles in regulating fundamental biological processes by suppressing the expression of target genes. Aberrant miRNA expression is commonly correlated with human diseases, including cancers. Anti-miRNA oligonucleotides provide an innovative therapeutic strategy for silencing disease-associated miRNAs. However, the clinical application of anti-miRNA therapy has been limited by formulation challenges and physiological delivery barriers. Here, to provide the safe and effective tumor-targeted delivery of anti-miRNAs, we designed carrier-free maleimide-functionalized anti-miRNAs (MI-Anti-miRNAs) that enable "piggybacking" onto albumin in vivo. These functionalized MI-Anti-miRNAs covalently bind to cysteine-34 of endogenous albumin within minutes. In addition to resulting in a markedly extended blood circulation lifetime, this strategy allows MI-Anti-miRNAs to "hitchhike" to the tumor site. Importantly, in situ-generated albumin-Anti-miRNAs are capable of intracellularly internalizing highly negatively charged anti-miRNA molecules and knocking down target miRNAs. In particular, MI-Anti-miRNAs that targeted miRNA-21, which is involved in tumor initiation, progression, invasion, and metastasis in several types of cancer, successfully repressed miRNA-21 activity, resulting in a superior antitumor activity in both solid and metastatic tumor models without causing systemic toxicity. This endogenous albumin-piggybacking approach using MI-Anti-miRNAs provides a simple and broadly applicable platform strategy for the systemic delivery of anti-miRNA therapeutics.

Exosomes: Cell-Derived Nanoplatforms for the Delivery of Cancer Therapeutics.

Exosomes are cell-secreted nanovesicles that naturally contain biomolecular cargoes such as lipids, proteins, and nucleic acids. Exosomes mediate intercellular communication, enabling the transfer biological signals from the donor cells to the recipient cells. Recently, exosomes are emerging as promising drug delivery vehicles due to their strong stability in blood circulation, high biocompatibility, low immunogenicity, and natural targeting ability. In particular, exosomes derived from specific types of cells can carry endogenous signaling molecules with therapeutic potential for cancer treatment, thus presenting a significant impact on targeted drug delivery and therapy. Furthermore, exosomes can be engineered to display targeting moieties on their surface or to load additional therapeutic agents. Therefore, a comprehensive understanding of exosome biogenesis and the development of efficient exosome engineering techniques will provide new avenues to establish convincing clinical therapeutic strategies based on exosomes. This review focuses on the therapeutic applications of exosomes derived from various cells and the exosome engineering technologies that enable the accurate delivery of various types of cargoes to target cells for cancer therapy.