Kwan Soo Hong

Tumor hypoxia is a pervasive feature of solid tumors that promotes malignant progression, metastatic dissemination, and resistance to chemotherapy, radiotherapy, and immunotherapy. At the same time, low oxygen tension creates a chemically exploitable vulnerability for selective drug activation. Hypoxia-activated prodrugs (HAPs) and activatable small-molecule theranostics are designed to remain comparatively inactive in oxygenated tissues and to undergo reductase-mediated conversion within hypoxic tumor regions, thereby releasing cytotoxic, targeted, immunomodulatory, or imaging-active species. In this Review, we organize recent advances according to the chemistry of the bioreductive trigger and the mechanism that links reduction to payload release or signal generation. We discuss nitroaromatic and nitroheterocyclic groups, azo linkages, N-oxides, quinones, azides, and redox-active transition-metal complexes, with emphasis on one-electron redox cycling, multielectron reduction, self-immolative fragmentation, and the influence of reduction potential and local oxygen concentration. Representative small-molecule systems are then used to illustrate how hypoxia activation can be integrated with fluorescence and multimodal imaging, phototherapy, immunomodulation, and targeted delivery. Finally, we examine the principal translational barriers including spatial and temporal heterogeneity of tumor oxygenation, reductase dependence, incomplete intratumoral activation, pharmacokinetic limitations, and the need for patient-selection biomarkers and outline design criteria for improving therapeutic index and clinical tractability. Together, these developments position hypoxia-responsive chemistry as a mechanistically tunable platform for precision drug delivery rather than simply a means of targeting oxygen-poor tumor regions.

Tumor hypoxia is a pervasive feature of solid tumors that promotes malignant progression, metastatic dissemination, and resistance to chemotherapy, radiotherapy, and immunotherapy. At the same time, low oxygen tension creates a chemically exploitable vulnerability for selective drug activation. Hypoxia-activated prodrugs (HAPs) and activatable small-molecule theranostics are designed to remain comparatively inactive in oxygenated tissues and to undergo reductase-mediated conversion within hypoxic tumor regions, thereby releasing cytotoxic, targeted, immunomodulatory, or imaging-active species. In this Review, we organize recent advances according to the chemistry of the bioreductive trigger and the mechanism that links reduction to payload release or signal generation. We discuss nitroaromatic and nitroheterocyclic groups, azo linkages, N-oxides, quinones, azides, and redox-active transition-metal complexes, with emphasis on one-electron redox cycling, multielectron reduction, self-immolative fragmentation, and the influence of reduction potential and local oxygen concentration. Representative small-molecule systems are then used to illustrate how hypoxia activation can be integrated with fluorescence and multimodal imaging, phototherapy, immunomodulation, and targeted delivery. Finally, we examine the principal translational barriers including spatial and temporal heterogeneity of tumor oxygenation, reductase dependence, incomplete intratumoral activation, pharmacokinetic limitations, and the need for patient-selection biomarkers and outline design criteria for improving therapeutic index and clinical tractability. Together, these developments position hypoxia-responsive chemistry as a mechanistically tunable platform for precision drug delivery rather than simply a means of targeting oxygen-poor tumor regions.

Steatotic liver disease is associated with advanced glycation end-product (AGE) accumulation, but the pathogenic AGE species and mechanisms remain unclear. We investigated whether Nε-(carboxymethyl)lysine (CML) induces hepatic fibrogenic responses and whether CML-associated programs in human liver organoids (HLOs) are reflected in patient biospecimens. AGE–RAGE pathway activity was assessed in three public liver transcriptomic cohorts, and CML and total AGEs were quantified in liver and serum. Models included C57BL/6J mice, HepG2 2D/3D systems, and multicellular HLOs; translational concordance was assessed by serum cytokine and liver proteomic profiling. AGE–RAGE pathway activity was elevated in NASH-related diagnostic and histological categories, and hepatic CML—but not total AGE or serum CML—was increased in steatosis. Oral CML activated AGE–RAGE- and tumor growth factor-β-related programs but caused minimal fibrosis; HepG2 models failed to reproduce CML-driven lipid accumulation. In HLOs, CML induced lipid accumulation and fibrogenic remodeling through a program distinct from oleic acid-driven lipotoxicity. Single-cell RNA sequencing revealed shifts in hepatocyte-, Kupffer-, and stellate-like populations, mitochondrial dysfunction in hepatocyte-like cells, and collagen assembly pathway activation. Functional assays confirmed oxidative stress, NF-κB-dependent cytokine release, stellate cell activation, and collagen deposition; selected responses were attenuated by N-acetylcysteine, clodronate, 2-deoxyglucose, or NF-κB inhibition. Steatosis biospecimens showed partial concordance with CML–HLO-associated inflammatory and fibrogenic programs. Collectively, CML preferentially accumulates in steatotic liver tissue and promotes fibrogenic responses in multicellular HLOs through mitochondrial dysfunction and immune-mediated stellate cell activation. These findings support HLOs as a human-relevant platform for investigating AGE-driven hepatic pathology associated with steatosis.

Multidrug resistance mediated by ATP-binding cassette transporter B1 (ABCB1) remains a major obstacle in nonsmall cell lung cancer (NSCLC) therapy. While its role in drug efflux is well established, whether elevated ABCB1 expression is associated with broader immune-related phenotypes has not been completely elucidated. Here, we examined hABCB1-overexpressing and drug-adapted NSCLC models to assess coordinated changes in drug resistance and immune susceptibility. Increased ABCB1 expression was associated with enhanced efflux activity and reduced sensitivity to chemotherapeutic agents. Across engineered and drug-selected systems, ABCB1-high cells showed decreased susceptibility to NK-92-mediated cytotoxicity. Pharmacological inhibition of transporter activity partially increased effector-mediated killing, supporting ABCB1 activity as a contributing factor, while indicating that additional mechanisms may also be involved. Proteomic and cytokine profiling suggested coordinated alterations in inflammatory and interferon-related signaling pathways. In a human lung cancer tissue microarray, elevated hABCB1 expression was inversely associated with CD3⁺ T-cell infiltration. Together, these findings support an association between elevated ABCB1 expression and both drug-resistance features and immune-related phenotypes in NSCLC. Further genetic and in vivo studies are required to define mechanistic causality and clinical relevance.

Theranostic prodrugs that integrate diagnostic and therapeutic functionalities represent a promising avenue for precision oncology. In this study, we report the rational design, synthesis, and preclinical evaluation of a nanobody‐based α _v β ₃ integrin‐targeted theranostic prodrug ( NBD ). The system incorporates a glutathione‐responsive disulfide linker to enable selective release of doxorubicin within the tumor microenvironment, alongside an aza‐BODIPY near‐infrared fluorophore that providesactivatable imaging capability. Compared to its cRGD peptide‐conjugated counterpart ( cRBD ), NBD demonstrated superior tumor selectivity, intracellular activation, and cytotoxic potency in α _v β ₃ ‐overexpressing cancer cell lines. In vivo studies using SKOV3 xenograft models confirmed prolonged tumor retention, enhanced drug accumulation, and potent tumor suppression, with minimal systemic toxicity. Moreover, real‐time imaging enabled precise monitoring of prodrug activation and distribution. These findings highlight the unique advantages of nanobody‐guided theranostic platforms in enabling targeted drug delivery, reducing off‐target effects, and facilitating image‐guided therapy. The modular design of NBD provides a versatile framework for advancing personalized cancer treatment strategies.

Cell-based immunotherapies have emerged as promising cancer treatment modalities, demonstrating remarkable clinical efficacy. As interest in applying immune cell-based therapies to solid tumors has gained momentum, experimental models that enable long-term monitoring and mimic clinical administration are increasingly necessary. This study explores the potential of scaffold-based cell culture technologies, specifically three-dimensional (3D) extracellular matrix (ECM)-like frameworks, as promising solutions. These frameworks facilitate unhindered immune cell growth and enable continuous cancer cell culture. The three-dimensional (3D) cell culture model was developed using tailored scaffolds for natural killer (NK) cell culture. Within this framework, A549 lung cancer cells were cocultured with NK cells, allowing real-time monitoring for up to 28 days. The expression of critical markers associated with anticancer drug resistance and epithelial-mesenchymal transition (EMT) was evaluated in cancer cells within this 3D culture context. Compared to conventional 2D monolayer cultures, this 3D scaffold-based culture revealed that solid tumor cells, specifically A549 cells, exhibited heightened resistance to anticancer drugs. Additionally, the 3D culture environment upregulated the expression of EMT markers namely vimentin, N-cadherin, and fibronectin, while NK and zEGFR-CAR-NK cells displayed anticancer effects. In the two-dimensional (2D) coculture, only zEGFR-CAR-NK cells exhibited such effects in the 3D coculture system, highlighting an intriguing inconsistency with the 2D culture model, further confirmed by in vivo experiments. This in vitro 3D cell culture model reliably predicts outcomes in NK immunotherapy experiments. Thus, it represents a valuable tool for investigating drug resistance mechanisms and assessing the efficacy of immune cell-based therapies. By bridging the gap between in vitro and in vivo investigations, this model effectively translates potential treatments into animal models and facilitates rigorous preclinical evaluations.

Natural killer (NK) cells play a crucial role in immunotherapy for cancer due to their natural ability to target and destroy cancer cells. However, current methods to visualize NK cells’ activity against tumors in live organisms are limited. We introduce an imaging method that non-invasively tracks NK cell activation by cancer cells through the STAT1 protein. To achieve this, we modified NK cells to include a specific genetic sequence that binds to STAT1 when activated. These engineered NK cells (GAS-NK) demonstrate their functionality through various biological tests and analysis. Observations of changes in cancer environments and patient-derived cancer organoid models further confirm the effectiveness of this approach. Our method provides a way to monitor NK cell activity, which could improve the prediction and effectiveness of NK cell-based cancer therapies, contributing to advances in cancer treatment.

Recently, extracellular vesicles (EVs) have been developed as therapeutic targets for various diseases. Biodistribution is crucial for EVs intended for therapeutic purposes because it can determine the degree of on‐ and off‐target effects. This study aimed to explore techniques to evaluate the biodistribution of unmodified EVs. We devised a novel quantitative polymerase chain reaction (qPCR)‐based assay to detect unmodified EVs by targeting mitochondrial deoxyribonucleic acid (mtDNA), a constituent of EVs. We focused on specific mtDNA regions that exhibited homologous variations distinct from their rodent mtDNA counterparts to establish this analytical approach. Herein, we successfully designed primers and probes targeting human and rodent mtDNA sequences and developed a highly specific and sensitive qPCR method. Furthermore, the quantification range of EVs isolated from various cells differed based on the manufacturer and cell source. IRDye 800CW‐labelled Expi293F EV mimetics were administered to the animals via the tail vein to compare the imaging test and mtDNA‐qPCR results. The results obtained from imaging tests and mtDNA‐qPCR to investigate EV biodistribution patterns revealed differences. The results revealed that our newly developed method effectively determined the biodistribution of unmodified EVs with high sensitivity and reproducibility.