What question did this study set out to answer?

This research aims to identify biomarkers related to primary resistance to TUSC2 gene therapy in NSCLC.

April 5, 2026

Abstract 391: TROP2 and PTEN are biomarkers of primary resistance to TUSC2 gene therapy in non-small cell lung cancer (NSCLC).

Puntos clave

This research aims to identify biomarkers related to primary resistance to TUSC2 gene therapy in NSCLC.
Established NSCLC patient-derived xenografts (PDXs) and organoids (PDXOs).
Screened 10 NSCLC cell lines for TUSC2 sensitivity using colony formation assays.
Evaluated TUSC2 sensitivity in 12 PDXOs with ATP-based viability assays after transfection.
Developed models of acquired resistance and treated with TUSC2 gene therapy.
Performed reverse-phase protein array (RPPA) analysis on 500 proteins to identify expression signatures.
Approximately 50% of NSCLC cell lines displayed primary resistance to TUSC2 gene therapy.
Significant expression alterations identified in resistant cell lines and PDXOs based on RPPA.
Low TROP2 expression and high PTEN expression correlated with primary resistance.
Overexpression of TROP2 enhanced TUSC2-induced cancer cell apoptosis.
Model-specific alterations in protein expression were observed between responders and non-responders.

Resumen

Abstract Primary resistance to targeted therapies, immunotherapies, and gene therapies in NSCLC continues to be a significant challenge. TUSC2 tumor suppressor gene therapy has shown promising anti-tumor efficacy by overcoming resistance to targeted therapy and enhancing checkpoint blockade immunotherapy, including in a mutant KRAS/LKB1-driven immunotherapy-resistant NSCLC model. TUSC2 protein expression is downregulated or absent in over 80% of NSCLC and 100% of SCLC cases., TUSC2 mediates cancer cell death through several mechanisms: inhibiting MAPK and mTOR signaling pathways, arresting cell growth, inducing programmed cell death, and activating immune responses. We established models primarily resistant to TUSC2 gene therapy to find biomarkers indicative of TUSC2 gene therapy resistance in NSCLC patient-derived xenografts (PDXs), PDX-derived organoids (PDXOs), and cell lines. A panel of 10 NSCLC cell lines screened for TUSC2 sensitivity showed resistance in 50% of the cell lines, as assessed by annexin V staining and colony formation assays. We evaluated TUSC2 sensitivity in 12 NSCLC PDXOs using ATP-based viability assays in 3D culture following TUSC2 or empty vector transfection. While some PDXOs were highly responsive to TUSC2 within 72 hours post-transfection, 50% of PDXOs exhibited primary resistance. We developed TC314AR (Acquired Resistance) PDX tumors and xenograft models (A549, H1299, H23AR) in NSG mice and treated them with TUSC2 gene therapy. 20-30% of tumors in every model showed resistance, with no significant reduction in size compared to the control tumors after treatment. Protein expression profiling using reverse-phase protein array (RPPA) analysis of 500 proteins showed distinct expression signatures, with several candidate biomarkers significantly altered in resistant cell lines and PDXOs. RPPA analysis of residual tumors from both the xenograft and PDX models revealed significant but model-specific alterations in protein expression between responders and non-responders. Comparative analyses across the three models showed low expression of TROP2 and high expression of PTEN as potential biomarkers of primary resistance. Overexpression of TROP2 in H1299 and H460 cells increased TUSC2-induced apoptosis. These findings suggest that TROP2 and PTEN may serve as biomarkers to predict TUSC2 response and guide therapeutic strategies in NSCLC. Citation Format: Ismail M. Meraz, Renduo Song, Shuhong Wu, Yi Xu, Meng Feng, Lihui Gao, Chenghui Ren, Qi Wang, Jun Li, Mourad Majidi, Jing Wang, Mark Berger, Jack A. Roth. TROP2 and PTEN are biomarkers of primary resistance to TUSC2 gene therapy in non-small cell lung cancer (NSCLC) 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 391.

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