Cancer Research Institute

Abstract Lymphocyte-activation gene 3 (LAG-3) is an inhibitory receptor expressed on exhausted CD8+ T cells and regulatory T cells (Tregs), and its blockade has been shown to enhance the anti-tumor effects of PD-1 blockade. Transcriptomic and clinical analysis of the METABRIC breast cancer cohort revealed that high LAG-3 expression was correlated with worse relapse-free and overall survival. Furthermore, radiation therapy (RT) improved survival outcomes only in patients with low LAG-3 expression not in patients with high LAG-3 expression. High LAG-3 expression was correlated with increased Treg abundance. In a 4T1 murine breast cancer model, RT combined with PD-1 blockade increased the proportion of LAG-3+ CD8+ T cells and Tregs, particularly in the tumor and spleen. These findings suggested that LAG-3 may mediate therapeutic resistance of RT combined with PD-1 blockade by expanding suppressive T-cell populations. Based on these, we hypothesized that LAG-3 blockade could restore anti-tumor immune response and enhance the therapeutic efficacy of RT combined with PD-1 blockade. Triple combination therapy (TCT) with RT, PD-1 blockade, and LAG-3 blockade delayed tumor growth in both irradiated and unirradiated tumors, reduced lung metastases, and improved survival. TCT significantly increased tumor-specific CD8+ T cells and memory T cells, reduced Tregs, and expanded activated natural killer cells. Mice achieving complete response following TCT rejected tumor rechallenge suggesting the tumor-specific memory response. Taken together, LAG-3 blockade might be a viable approach to optimize the therapeutic efficacy of RT combined with PD-1 blockade. This work was supported by grants from the National Research Foundation of Korea (NRF-2023R1A2C3003782). Citation Format: In Ah Kim, Yoomin Kim, Seung Hyuck Jeon. LAG-3 is associated with poor prognosis and LAG-3 blockade enhances the efficacy of PD-1 blockade combined with radiation therapy in breast cancer [abstract]. In: Proceedings of the AACR Immuno-Oncology Conference (AACR IO): Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2026 Feb 18-21; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2026;14(2 Suppl):Abstract nr A041.

Acute kidney injury (AKI) remains a major clinical challenge resulting from the intertwined processes of oxidative stress and macrophage-driven inflammation, both converging on mitochondrial dysfunction. We developed a glucosylated albumin nanoplatform (Glc6-AD11-Alb) designed to exploit glucose transporter 1-mediated uptake in inflammatory M1 macrophages while preserving the intrinsic antioxidant properties of albumin. Physicochemical characterization confirmed reproducible synthesis with defined degrees of functionalization and stable physicochemical properties. In vitro, Glc6-AD11-Alb demonstrated selective uptake in M1 macrophages and significantly reduced intracellular reactive oxygen species, validating its dual role in immune modulation and redox regulation. Positron emission tomography imaging with Cu-64 radiolabeling revealed preferential renal accumulation in ischemia-reperfusion injury (IRI) models, supporting macrophage-targeted delivery. In vivo, administration of Glc6-AD11-Alb attenuated renal dysfunction, suppressed pro-inflammatory and oxidative markers, and promoted tubular regeneration in pre- and post-treatment settings. Importantly, Glc6-AD11-Alb directly protected renal tubular epithelial cells by restoring mitochondrial membrane potential under oxidative and hypoxic stress. Seahorse metabolic flux analysis further confirmed enhanced oxidative phosphorylation, reduced glycolytic dependency, and improved coupling efficiency, indicating recovery of mitochondrial bioenergetics. Transmission electron microscopy demonstrated preservation of mitochondrial ultrastructure, including intact cristae and elongated morphology, consistent with improved ATP synthesis capacity. Glc6-AD11-Alb acts through complementary mechanisms of macrophage-targeted immune modulation and mitochondrial protection, thereby disrupting the vicious cycle of inflammation and oxidative stress in AKI. This nanoplatform represents a clinically translatable therapeutic strategy with potential to improve outcomes in patients with ischemic kidney injury.

Background: Huntington's disease (HD) is a devastating neurodegenerative disorder caused by CAG repeat expansion in the HTT gene, resulting in a polyglutamine-expanded huntingtin (HTT) protein that forms toxic aggregates. Although heat-shock proteins are known to facilitate the refolding or clearance of misfolded proteins, their precise role in modulating protein aggregation in HD remains unclear. Here, we explore the function of caseinolytic peptidase B (ClpB), a mitochondrial AAA+ ATPase and heat-shock protein, in maintaining proteostasis and synaptic integrity in HD. Methods: We examined how CLPB loss or overexpression in human embryonic kidney 293T (HEK293T) cells impacted the aggregation of wild-type HTT (HTT-Q23) and mutant HTT (HTT-Q79). In parallel, AAV-mediated ClpB knockdown or overexpression was applied to the striatum of HD model mice. and HTT aggregation and inhibitory synaptic alterations were assessed. Aggregate burden was quantified via immunostaining, and inhibitory synapse density was evaluated using VGAT immunohistochemistry and electrophysiological recordings. Results: In HEK293T cells, CLPB knockout led to abnormal aggregation of HTT-Q23 while CLPB overexpression reduced the size of HTT-Q79 aggregates. In the mouse striatum, ClpB knockdown increased HTT-Q23 aggregate numbers and altered HTT-Q79 aggregation morphology, whereas CLPB overexpression restored the density and size of VGAT-positive inhibitory synapses and improved inhibitory synaptic transmission in HD model mice. These effects of CLPB overexpression were associated with a reduced mitochondrial aggregation burden, suggesting that ClpB contributes to mitochondrial protein quality control. Conclusions: These results demonstrate that ClpB regulates both physiological and pathological HTT aggregation and contributes to maintaining inhibitory synaptic integrity. By modulating mitochondrial proteostasis, ClpB acts as a protective factor in HD pathology, highlighting its potential as a therapeutic target for neurodegenerative disorders characterized by protein misfolding.

Cisplatin (CDDP) resistance remains a major clinical challenge in the treatment of head and neck squamous cell carcinoma (HNSC). Our group identified ATPase copper transporting beta (ATP7B) as a mediator of CDDP resistance through its role in drug efflux and small extracellular vesicle (sEV) secretion. Herein, we uncovered a novel mechanism by which ATP7B regulates sEV dynamics and the intercellular transmission of CDDP resistance. Using transcriptomic analyses of HNSC datasets, we demonstrate that ATP7B expression correlates with endocytosis- and epithelial-mesenchymal transition (EMT)-related gene sets and with elevated levels of EV-associated proteins. CDDP-resistant HNSC cells exhibited upregulated ATP7B, Rab5/Rab7, and preferentially secreted HSP90- and EpCAM-rich sEVs. These sEVs were leading to increased ATP7B expression and reduced CDDP sensitivity in recipient cells. A pharmacological inhibition of sEV biogenesis with GW4869 suppressed ATP7B and Atox1 expressions, inhibited late endosome maturation, and significantly enhanced CDDP-induced apoptosis in HNSC cells. In vivo, GW4869 reduced the sEV protein content and ATP7B expression in xenograft tumors. These findings establish that ATP7B is a critical modulator of sEV cargo and resistance propagation. Our results highlight a previously unrecognized ATP7B–sEV axis driving chemoresistance and identify sEV inhibition as a promising strategy to overcome therapeutic failure in HNSC.