Abstract 3017: Profiling patient response to TTK/PLK1 dual antagonist BAL0891 using 3D patient-derived organoid model in a microphysiological system

Abstract Introduction: Dysregulation of cell cycle checkpoints in cancer cells drives uncontrolled proliferation and tumor progression. Threonine Tyrosine Kinase (TTK) and Polo-like Kinase 1 (PLK1) are key regulators of the spindle assembly checkpoint (SAC) during mitotic division. Their overexpression is linked to tumor aggressiveness and poor prognosis in multiple malignancies. BAL0891, a first-in-class dual TTK/PLK1 inhibitor disrupts SAC integrity, increases cytoplasmic DNA, activates the cGAS/STING pathway, induces senescence-associated secretory phenotypes (SASP), and elevates PD-L1 expression, suggesting potential for synergy with immune checkpoint inhibitors. To explore patient-specific responses and identify predictive biomarkers of sensitivity to BAL0891, we utilized 3D patient-derived organoid (PDO) models within a microphysiological system (MPS), offering physiologically relevant insights beyond traditional models. Methods: PDOs from renal cell carcinoma, triple-negative breast cancer, gastric cancer, and colorectal cancer were established in collaboration with Qureator. These PDOs were cultured in Qureator’s CurioChips, which incorporate hydrogel-based extracellular matrix (ECM) to mimic the tumor tissue. Following organoid stabilization, BAL0891 was administered and cytotoxicity was assessed through live/dead dye staining and organoid volume measurements. PD-L1 expression was analyzed via flow cytometry to evaluate the potential for combination therapy with anti-PD-L1/PD-1 inhibitors. Cytokine profiling was conducted using multiplex secretome analysis to assess changes in the co-cultures. Additionally, RNA sequencing was performed to identify gene expression signatures associated with sensitivity and resistance to BAL0891. Results: BAL0891 exhibited variable cytotoxicity across PDOs, with a subset demonstrating resistance. Responding PDOs showed SASP, confirmed by β-Galactosidase staining, increased PD-L1 expression, and distinct pro-inflammatory cytokine profiles compared to non-responders. Preliminary cytokine analyses indicates that BAL0891 reshapes the immune landscape in sensitive PDOs. Ongoing RNA sequencing analysis aims to identify gene clusters associated with sensitivity to BAL0891, offering potential biomarkers or therapeutic targets. Conclusion: This study highlights the value of PDO-based 3D MPS in evaluating patient-specific responses to BAL0891 and identifying predictive biomarkers. These findings establish a foundation for patient stratification and personalized treatment strategies in clinical trials combining BAL0891 with immune checkpoint inhibitors. Further analysis of gene signatures may provide insights into potential therapeutic targets and improve our understanding on the mechanism driving TTK/PLK1 inhibition and its combination with immunotherapy. Citation Format: Junfeng Wang, MinKyung Kang, Delaney Donnelly, Jihye Baek, Bushra Rajput, Byungjun Lee, Hyeon-geun Park, Yunha Shin, Tsung-Li Liu, Aneesh Sathe, Yangji Kim, Kyusuk Baek, Sanghee Yoo, Salman Ahmed, Jae Jung Lee, Seunghyun Ma. Profiling patient response to TTK/PLK1 dual antagonist BAL0891 using 3D patient-derived organoid model in a microphysiological system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3017.