Strategies to inhibit FGFR4 V550L-driven rhabdomyosarcoma

ABSTRACT: Rhabdomyosarcoma (RMS) is a paediatric cancer driven either by a fusion protein (e.g. PAX3-FOXO1) or by mutations in key signalling molecules (e.g. RAS or FGFR4). Despite the latter giving potential for precision medicine approaches in RMS, there are no such treatments implemented in the clinic yet. In order to identify and test novel precision therapy strategies, appropriate cellular and mouse models are crucial. We have here thoroughly characterized a RMS patient-derived cell line model, RMS559, which harbours a FGFR4 V550L activating mutation with high allelic frequency (0.8). Importantly, we show that RMS559 cells are oncogenically dependent on FGFR4 signalling by treatment with the pan-FGFR inhibitor LY2874455. Phosphoproteomic analysis identified RAS/MAPK and PI3K/AKT as the major druggable signalling pathways downstream of FGFR V550L. Inhibitors against these pathways inhibited cell proliferation. Furthermore, we found that FGFR4 V550L is dependent on HSP90 and inhibitors targeting HSP90 efficiently restrain proliferation. Recently, FGFR4 specific inhibitors have been developed. While two of these, BLU-9931 and H3B-6527, did not efficiently inhibit FGFR4 V550L, probably because of the gatekeeper mutation (V550L), one of them, FGF401 inhibited FGFR4 V550L and cell proliferation at low nanomolar concentrations. Finally, we developed a mouse model using RMS559 cells and tested the in vivo efficacy of LY2874455 and FGF401. While LY2874455 inefficiently inhibited growth, FGF401 completely abrogated tumour growth in vivo.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Sachin Singh  

LAB HEAD: Jørgen Wesche

PROVIDER: PXD029719 | Pride | 2022-10-19

REPOSITORIES: Pride