Abstract 164: Restoring TUSC2 function boosts NK cell cytotoxicity and antitumor immunity in vivoand in vitro.

Abstract Background: Tumor Suppressor Candidate 2 (TUSC2), located on chromosome 3p21.3, is frequently deleted in multiple human cancers, including non-small cell lung carcinoma (NSCLC), small cell lung carcinoma (SCLC), mesothelioma, breast cancer, and head-and-neck cancers. Loss of TUSC2 is associated with reduced survival and increased tumor aggressiveness. Although TUSC2 is known to suppress tumor cell proliferation and induce apoptosis, its regulatory role in the immune system—particularly in innate lymphoid populations—remains insufficiently defined. Building on our prior work identifying TUSC2 as a mitochondrial protein involved in calcium regulation and immune modulation, we hypothesized that TUSC2 exerts antitumor effects in part by enhancing NK cell cytotoxicity. Methods Tusc2 knockout (Tusc2 KO) and wild-type (Tusc2 WT) mice were challenged with syngeneic tumor cells (344SQ) and treated with TUSC2-expressing lipoparticles (quaratusugene ozeplasmid, Quar Oze). The therapeutic group received Quar Oze after tumor establishment starting at day 8 from cell line injection, while prophylaxis group received Quar Oze before tumor establishment, starting 2 days before injection of cell lines. Control groups received empty lipoparticles. After three weeks from cell line injection, tumor volumes were assessed, and mice were euthanized for collection of tumors, spleens, and tumor-draining lymph nodes (TDLN). Immune cell phenotypes and cytotoxic markers were analyzed using flow cytometry. In vitro studies evaluated NK cell cytotoxic function following Quar Oze treatment by measuring CD107a degranulation and CellTrace Violet-based proliferation Results In the therapeutic treatment group, 67% of Tusc2 KO mice and 33% of Tusc2 WT mice achieved complete tumor regression, with all remaining mice showing significant tumor reduction compared with controls. Prophylactic administration did not induce complete tumor clearance but consistently reduced tumor growth across all mice. Immune profiling of the tumor microenvironment revealed that Quar Oze robustly enhanced NK cell cytotoxicity, particularly increasing granzyme B and perforin expression. In vitro assays confirmed that TUSC2 restoration significantly increased NK cell degranulation and proliferation, supporting the in vivo findings. Conclusion TUSC2 acts as a critical enhancer of innate antitumor immunity by boosting NK cell cytotoxic function. Therapeutic delivery of TUSC2 via Quar Oze suppresses tumor progression and, in many cases, drives complete tumor elimination. These results highlight TUSC2 as a potent immunomodulatory tumor suppressor and support its development as a dual-function therapeutic that directly targets tumor cells while also activating NK cell-mediated immunity Citation Format: Muna Ahmed Eltayeb A. Mohammed, Salvador Gonzalez Ochoa, Jane Tonello, Thanigaivelan Kanagasabai, Mark S. Berger, Alla Ivanova, Anil Shanker. Restoring TUSC2 function boosts NK cell cytotoxicity and antitumor immunity in vivoand in vitro abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 164.