17A novel immuno-oncology preclinical pipeline to study FGFR2 fusion-driven cholangiocarcinoma
Alexandra Wolf, Emily R Bramel, Mattias Facciuto, Sara Young, Miguel Torres, Shalini Nath, Vincenzo Mazzaferro, Myron Schwartz, Swan Thung, Amaia Lujambio, Benjamin Hopkins, Anna Tocheva, Daniela SiaAbstract
Background
Intrahepatic cholangiocarcinoma (iCCA) is a rare, but deadly biliary tract cancer, increasing in incidence globally. One in five patients harbor a genetic activation of FGFR2 (fibroblast growth factor 2), where gene fusions enhance neoplastic growth. Inhibitors of FGFRs have displayed sub-optimal results—patients with advanced stage iCCA acquire drug resistance. Therefore, novel, alternative therapeutics for FGFR-driven iCCAs are crucial. A major limitation is that current preclinical models do not mimic the immunobiology of human disease.
Methods
We generated a mouse model harboring the FGFR2-PPHLN1 fusion (or its murine homolog mFgfr2-Pphln1) and activated YAP1 via hydrodynamic tail vein injection, and established cell lines and organoids. Additionally, the V565F resistance mutation was introduced in the FGFR2 fusion gene. We characterized tumors using RNA-sequencing (n = 3 per group) and spectral cytometry (n = 3-7 per group) and performed cross-species analysis using published human datasets [OEP001105, (n = 262); GSE33327, (n = 149)] and molecular characterization by GSEA. In vitro and in vivo drug treatment with reversible and irreversible FGFR inhibitors was performed.
Results
FGFR2-driven murine tumors were molecularly and immunologically similar to human iCCA carrying FGFR2 alterations, with accumulation of tumor-associated neutrophils (TANs, 60% of all CD45+) and impaired T cell infiltration. Organoids reproduced clinical responses to reversible and irreversible FGFR inhibitors, while also showing a sustained response to the reversible inhibitor derazantinib in the FGFR2V565F-PPHLN1 organoids. Mice exhibited response to derazantinib but no synergy was observed when combined with immune checkpoint inhibitor PD-L1.
Conclusion
Our mouse model and it’s in vitro derivatives recapitulate the immunobiology and therapeutic sensitivities of human disease. Inter-species and cross-species analyses suggest a critical role of FGFR2 fusions in shaping a cold tumor microenvironment with accumulation of TANs in both humans and mice. Poor sensitivity to ICI in vivo suggests the need for novel therapeutic strategies harnessing the immunosuppressive nature of these tumors.