9Therapeutic Targeting of the KRAS in BTC Background
Farinaz Barghi, Ming Zhao, Erkan Yuca, Kurt Evans, Yasmeen Rizvi, Maria Gabriela Raso, Nakul M Shah, David Hong, Milind Javle, Funda Meric-BernstamAbstract
Background
KRAS mutations are highly prevalent in biliary tract cancer (BTC), including cholangiocarcinoma (CCA), underscoring the need for KRAS-targeted therapies. While KRAS G12C mutations are rare (6%), the more common G12D (41%) and G12V (23%) variants warrant investigation. TROP2-targeted antibody–drug conjugates (ADCs) show promising activity in multiple tumors, and TROP2 is expressed in BTC; however, the link between KRAS signaling and TROP2 regulation remains unclear. We hypothesized that KRAS inhibition may modulate TROP2 expression and enhance TROP2-ADC efficacy, supporting combination therapy in KRAS-driven CCA. Accordingly, we evaluated RAS(ON) inhibition effects on tumor growth, TROP2 expression, and combining RAS(ON) inhibitors with TROP2-ADCs.
Methods
CCA (EGI-1, RBE, YSCCC) and isogenic BTC cells (H69 WT, H69-G12D) were treated with RAS(ON) multi-selective inhibitor RMC-7977 or RAS(ON) G12D-selective inhibitor RMC-9945 to determine IC50 by Sulforhodamine B assay and assess colony formation. TROP2 expression and glycosylation were analyzed by immunoblot, qRT-PCR, and PNGase F. Synergy with TROP2 ADCs Sacituzumab govitecan (SG) and Datopotamab deruxtecan (Dato-DXd) was evaluated using the Chou–Talalay method. Antitumor activity was tested in EGI-1 xenografts and CCA PDX models, with tumor growth (T/C) and event-free survival (time to tumor doubling) analyzed per NCI PDXNET and Kaplan–Meier guidelines.
Results
KRAS-mutant CCA cells were sensitive to RMC-9945 (in G12D-mutant cells) and RMC7977. RAS inhibition induced TROP2 overexpression in CCA xenografts and increased both expression and glycosylation of TROP2 in KRAS-mutant cells. Combining RAS(ON) inhibitors with TROP2 ADCs (SG or Dato-DXd) produced synergistic growth inhibition in vitro. In vivo, RAS(ON) inhibitor monotherapy demonstrated antitumor activity with tumor growth inhibition and delayed progression but without tumor regression, indicating that effective combinations are needed for durable tumor growth control.
Conclusions
We identified a novel link between KRAS inhibition and TROP2 regulation. Dual KRAS/TROP2 targeting is a promising strategy in KRAS-driven CCA. In vivo combination studies are ongoing to define therapeutic benefits.