Figure 4. IACS-13909 suppresses the proliferation and MAPK pathway signaling of osimertinib-resistant EGFR^mut NSCLC cells harboring RTK-bypass in vitro.

(A) Activity of osimertinib in EGFR^mut HCC4006 and HCC4006-OsiR models, determined by clonogenic assays. N=3. (B) The level of various RTKs and EMT markers in HCC4006 parental (Par) and OsiR models. The OsiR models were maintained in the presence of 1 μM osimertinib. To generate samples for signaling analysis, cells were cultured in the absence of osimertinib for one day, then treated with DMSO or 1 μM osimertinib for 2 hours before being harvested and processed for Western blotting. (C) Activity of IACS-13909 in EGFR^mut HCC4006 and HCC4006-OsiR models, determined by in vitro clonogenic assays. N=4~8. (D-E) Anti-proliferative activity of IACS-13909 in combination with osimertinib in HCC4006 (D) and HCC4006-OsiR (E) cell lines, determined by in vitro clonogenic assays. Percent of inhibition, calculated from quantitated cell number is provided in Figures S3A and S3B. Bliss score calculation is provided in Figure S3C and S3D. N=4. (F) Heatmap from gene expression analysis showing the impact of osimertinib (100 nM) and IACS-13909 (3 μM) either as single agent or in combination on a MAPK signature (MPAS-plus signature) in HCC4006-OsiR cells over a timecourse in vitro. N=3.