Dokyung Jung ¹, Sanghee Shin ², Sung-Min Kang ¹, Inseong Jung ², Suyeon Ryu ¹, Soojeong Noh ², Sung-Jin Choi ², Jongwon Jeong ², Beom Yong Lee ², Kwang-Soo Kim ², Christine Seulki Kim ², Jong Hyuk Yoon ³, Chan-Hyeong Lee ¹, Felicitas Bucher ⁴, Yong-Nyun Kim ⁵, Sin-Hyeog Im ^{6 7 8}, Byoung-Joon Song ⁹, Kyungmoo Yea ^{2 10}, Moon-Chang Baek ¹

¹Department of Molecular Medicine, CMRI, Exosome Convergence Research Center (ECRC), School of Medicine, Kyungpook National University, Daegu, Republic of Korea.
²Department of New Biology, DGIST, Daegu, Republic of Korea.
³Department of Neural Development and Disease, Korea Brain Research Institute, Daegu, Republic of Korea.
⁴Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
⁵Division of Translational Science, National Cancer Center 323, Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do, Republic of Korea.
⁶Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Gyeongsangbuk-do, Republic of Korea.
⁷Institute of Convergence Science, Yonsei University, Seoul, Republic of Korea.
⁸ImmunoBiome, Pohang, Republic of Korea.
⁹Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism (NIAAA), Bethesda, Maryland, USA.
¹⁰New Biology Research Center, DGIST, Daegu, Republic of Korea.

Moon-Chang Baek and Kyungmoo Yea contributed equally to this work.
Correspondence: Moon-Chang Baek, Kyungmoo Yea

T cell-derived small extracellular vesicles (sEVs) exhibit anti-cancer effects. However, their anti-cancer potential should be reinforced to enhance clinical applicability. Herein, we generated interleukin-2-tethered sEVs (IL2-sEVs) from engineered Jurkat T cells expressing IL2 at the plasma membrane via a flexible linker to induce an autocrine effect. IL2-sEVs increased the anti-cancer ability of CD8⁺ T cells without affecting regulatory T (T_reg) cells and down-regulated cellular and exosomal PD-L1 expression in melanoma cells, causing their increased sensitivity to CD8⁺ T cell-mediated cytotoxicity. Its effect on CD8⁺ T and melanoma cells was mediated by several IL2-sEV-resident microRNAs (miRNAs), whose expressions were upregulated by the autocrine effects of IL2. Among the miRNAs, miR-181a-3p and miR-223-3p notably reduced the PD-L1 protein levels in melanoma cells. Interestingly, miR-181a-3p increased the activity of CD8⁺ T cells while suppressing T_reg cell activity. IL2-sEVs inhibited tumour progression in melanoma-bearing immunocompetent mice, but not in immunodeficient mice. The combination of IL2-sEVs and existing anti-cancer drugs significantly improved anti-cancer efficacy by decreasing PD-L1 expression in vivo. Thus, IL2-sEVs are potential cancer immunotherapeutic agents that regulate both immune and cancer cells by reprogramming miRNA levels.