FGFR2 fusion-driven cholangiocarcinoma is characterized by a distinct neutrophil-enriched tumor microenvironment in a syngeneic murine model.
TL;DR
The syngeneic murine Ff-iCCA model is introduced, providing a platform for functional investigation of cancer cell-TME crosstalk in this molecular subtype, and overcoming the key limitation of prior models relying on human transgenes in immunodeficient hosts.
Abstract
Background
&
Aims
Fibroblast growth factor receptor 2 gene (FGFR2) rearrangements are among the most common oncogenic drivers in intrahepatic cholangiocarcinoma (iCCA). While FGFR inhibitors are clinically approved, primary and secondary resistance remain major limitations. Preclinical investigation of resistance mechanisms, including cancer cell-extrinsic crosstalk, is hampered by current models that rely on human FGFR2-fusion transgenes in immunodeficient hosts. We therefore aimed to generate an entirely murine FGFR2-fusion driven iCCA (Ff-iCCA) model to study immunomodulatory mechanisms in the tumor microenvironment (TME).
Methods
A syngeneic cholangiocyte organoid-based iCCA mouse model was engineered via endogenous chromosomal rearrangement of the Fgfr2 gene combined with Trp53 deletion (PFf) and other co-occurring genetic alterations. KrasG12D-mutated lines (PK) served as comparison. TME characterization was performed using 30-plex spatial proteomics on ∼250,000 cells. Bulk RNA-sequencing was conducted on FGFR inhibitor-treated PFf and PK organoids. Pharmacodynamics of FGFR inhibition on Ff-iCCA were assessed by immunostaining and quantitative RT-PCR.
Results
Intrahepatic implantation produced well-differentiated Ff-iCCA with morphologic features resembling human small duct type iCCA. In immunocompetent hosts, additional co-alterations were required for tumor penetrance, with Pten deletion being most robust with 75%. Compared to KRAS-driven iCCA, Ff-iCCA showed a significantly increased infiltration by Ly-6C/G+ neutrophils (19-fold, p=0.004) and CD8+ T cells (8-fold, p<0.001). Transcriptome analysis revealed increased chemokine expression in PFf versus PK organoids, which was not reversed by FGFR inhibition. Ff-iCCA responded to FGFR inhibition with a 6.5-fold reduced proliferation in vivo (p=0.029), without observation of significant TME remodeling.
Conclusions
Our syngeneic murine Ff-iCCA model recapitulates hallmarks of human FGFR2-fusion iCCA, providing a platform for functional investigation of cancer cell-TME crosstalk in this molecular subtype. IMPACT AND IMPLICATIONS This study introduces the first fully syngeneic, endogenously engineered murine model of FGFR2-fusion driven iCCA, overcoming the key limitation of prior models relying on human transgenes in immunodeficient hosts. The model faithfully recapitulates hallmarks of human FGFR2-fusion iCCA, including a small duct type morphology and a distinct neutrophil-enriched tumor immune microenvironment, validating its translational relevance. The finding that an upregulated chemotaxis signature in FGFR2-fusion persists despite FGFR inhibition, alongside upregulation of interferon-stimulated genes upon treatment, points to compensatory immunomodulatory mechanisms that remain to be mechanistically resolved. Overall, this work provides a physiologically relevant platform to interrogate cancer cell-tumor microenvironment crosstalk in FGFR2-fusion driven iCCA.