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ORIGINAL RESEARCH article

Front. Immunol.

Sec. Cancer Immunity and Immunotherapy

Volume 16 - 2025 | doi: 10.3389/fimmu.2025.1658580

Signaling intact membrane-bound IL-15 enables potent anti-tumor activity and safety of CAR-NK cells

Provisionally accepted
Xiaodi  XuXiaodi Xu1Peiyu  CaoPeiyu Cao1Meng  WangMeng Wang1Yan  WanYan Wan1Shuwen  SunShuwen Sun1Yuxin  ChenYuxin Chen1Yilin  LiuYilin Liu1Tong  SuTong Su1Ge  GaoGe Gao1Xinze  LiuXinze Liu2Weixiang  ZhongWeixiang Zhong1Xi  ChenXi Chen1Xiaoyuan  LuXiaoyuan Lu3Buze  ChenBuze Chen1Junnian  ZhengJunnian Zheng4*Gang  WangGang Wang1*Huizhong  LiHuizhong Li1*
  • 1Cancer Institute, Xuzhou Medical University, Xuzhou, China
  • 2The Second Clinical Medical School, Nanjing Medical University, Nanjing, China
  • 3Department of Obstetrics and Gynecology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
  • 4Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China

The final, formatted version of the article will be published soon.

Background: Chimeric antigen receptor (CAR)-NK cells are a promising and safe alternative to CAR-T cells. However, the limited persistence in vivo restricts their clinical application and sustained therapeutic responses. IL-15 has been extensively used to improve CAR-NK cell persistence and effectiveness. Nevertheless, accumulation of IL-15 might induce uncontrolled proliferation of CAR-NK cells and thus lead to fatal side-effects. Therefore, it is essential to develop a safe and effective alternative strategy to improve the persistence and anti-tumor activity of CAR-NK cells. Methods: A signaling intact membrane-bound IL-15 (mbIL-15) was designed by fusing IL-15 and full-length IL-15Rα and was systematically compared with secretory IL-15 (sIL-15) in a B7H3-targeting CAR-NK cell system regarding their functionality and safety through various in vitro and in vivo experiments. Results: Both expression of sIL-15 or mbIL-15 significantly enhanced the proliferation by activating STAT5 and improved anti-tumor activity of CAR-NK cells in vitro and in vivo. Although CAR-NK cells with sIL-15 quickly eliminated intraperitoneal ovarian cancer, the mice experienced severe consequences, including dysregulated CAR-NK cell expansion, intense inflammatory responses, and irreversible organ damages. In contrast, CAR-NK cells carrying mbIL-15 showed moderate cell proliferation and potent tumor killing activity without observable adverse effects in both local treatment and systemic administration models. Conclusion: Head-to-head comparative studies demonstrated that signaling intact mbIL-15 significantly improved therapeutic efficacy and safety of CAR-NK cells compared to sIL-15, which provided preclinical evidence for future clinical development.

Keywords: CAR-NK cells, Immunotherapy, Membrane-bound IL-15, solid tumors, Safety

Received: 02 Jul 2025; Accepted: 16 Sep 2025.

Copyright: © 2025 Xu, Cao, Wang, Wan, Sun, Chen, Liu, Su, Gao, Liu, Zhong, Chen, Lu, Chen, Zheng, Wang and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Junnian Zheng, jnzheng@xzhmu.edu.cn
Gang Wang, wangg@xzhmu.edu.cn
Huizhong Li, lhz@xzhmu.edu.cn

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