Figure 4 from Resistance to Selective FGFR Inhibitors in <i>FGFR-</i>Driven Urothelial Cancer

Functional characterization of FGFR2/3 kinase domain mutations in Ba/F3 cell models. A, IC50 values of eight selective FGFR inhibitors in viability assays against FGFR3::TACC3 with a WT kinase domain or harboring mutations found in postprogression patient samples. IC50 values (nmol/L) are reported as means of ≥3 independent datasets (see Supplementary Table S3). B, Immunoblot analysis confirming the ability of erdafitinib to abrogate intracellular signaling in FGFR3::TACC3 WT Ba/F3 cells, while resistance was observed in N540K, V553M, V555L, V555M, and L608V mutants. C, Higher concentrations of pemigatinib (100–300 nmol/L) were required to abrogate FGFR3 signaling in FGFR3::TACC3 V553L Ba/F3 compared with erdafitinib (10–30 nmol/L). D, Exposing FGFR3::TACC3 WT, N540K, and V555L Ba/F3 cells to erdafinitib corroborated the findings of resistance to erdafinitib, and confirmed the role of “molecular brake disruption” of the N540K mutant. E and F, Functional characterization of FGFR2 L551F mutation in Ba/F3 cells harboring the FGFR2::BICC1 transcript. A representative study of a cell viability assay is reported at the top (E), and IC50 values (nmol/L) are reported at the bottom as means of ≥3 independent datasets (F).