Abstract 1022: NFKBIA amplification attenuates B2M expression in NKX2.1-amplified lung adenocarcinoma, indicating immune evasion potential

Abstract Introduction: Lung adenocarcinoma (LUAD) is the predominant subtype of non-small cell lung cancer, accounting for approximately 40% of cases. With growing insights into tumor immunology and the advancement of immunotherapy, LUAD has shown remarkable therapeutic benefits in clinical trials. NKX2.1 is located in the 14q13.3 amplification interval and is the most frequently amplified genes in LUAD. NFKBIA, also resides in this region, is frequently co-amplified with NKX2.1. NFKBIA encodes IκBα, an inhibitor of NF-κB transcription factors that prevents their activation. A major challenge in lung cancer immunotherapy is the loss of major histocompatibility complex (MHC) class I expression. β2-microglobulin (B2M) is an essential subunit of MHC class I molecules and is crucial for presenting tumor antigens to T cells. Loss of B2M expression contributes to immune evasion and is regulated by the NF-κB signaling pathway. We hypothesize that NFKBIA amplification suppresses B2M, impairing immune responses and reducing immunotherapy efficacy. This study investigates whether reducing NFKBIA can restore B2M and enhance immunotherapy in NKX2.1 amplified LUAD. Methods: Multiple LUAD cell lines were treated with TNF-α to activate NF-κB. Stable cell lines with CRISPR-mediated NFKBIA knockout or overexpression were generated to assess effects on NF-κB activity and B2M expression. Results: Western blot analysis revealed that cell lines with high IκBα expression showed low B2M expression, suggesting that elevated IκBα inhibits NF-κB activation and reduces transcription of its target genes. TNF-α treatment significantly increased B2M expression within 12 h, with variable duration across cell lines. H3122 and HCC827 maintained elevated B2M levels for more than 5 days, while H23 and H661 showed transient induction returning to baseline within 3 days. These differences may serve as potential biomarkers predicting immunotherapy response. H3122 and H23 cells with NFKBIA knockout exhibited increased baseline B2M levels and enhanced induction after TNF-α treatment. Conversely, MGH006 and H2228 cells with NFKBIA overexpression showed reduced baseline B2M and diminished induction following TNF-α stimulation. Further studies on NFKBIA’s role in NF-κB signaling and validation using clinical LUAD samples are ongoing. Conclusion: TNF-α-mediated NF-κB activation enhances B2M expression in LUAD, with duration varying by cell line. NFKBIA knockout increases, and overexpression decreases, B2M and NF-κB activation. NFKBIA may serve as a prognostic biomarker and therapeutic target to improve immunotherapy efficacy. Citation Format: Ka Yee Li, Anthony J. Iafrate. NFKBIA amplification attenuates B2M expression in NKX2.1-amplified lung adenocarcinoma, indicating immune evasion potential [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 1022.