FIGURE 1 from Functional Heterogeneity in MET Pathway Activation in PDX Models of Osimertinib-resistant EGFR-driven Lung Cancer

Generation of spatial and temporally heterogenous osimertinib-resistant EGFR-mutant NSCLC PDX models and treatment study design. A, Schematic diagram of the prospective clinical trial of LAT for osimertinib-treated EGFR-mutant lung cancer (RT: radiotherapy). PDXs were generated from osimertinib-resistant tumor tissue either at first or second progression on osimertinib or after standard of care (S.O.C) therapy. B, Multi-region and temporal tumor samples from surgical resections or biopsies used for PDX generation are shown for each individual patient. Putative mechanism of resistance to osimertinib as evidenced by exome and or transcriptome sequencing (Roper et al., Cell Reports Medicine 2020) is shown below each set of PDXs. Color denotes timing of sample acquisition. Red: first progression on osimertinib; Green: second progression on osimertinib; Blue: progression on S.O.C treatment. C, Illustrations of PDX generation from 3 patients with EGFR-mutant lung cancer with MET polysomy by FISH (MET ≥ 4.0 and MET/CEP7 ratio is MET amplification by FISH (MET/CEP7 ratio ≥2.0 or ≥6 MET copies per cell) as a mechanism of resistance to osimertinib. D, Study design for treatment with MET inhibitor (savolitinib) with a third-generation EGFR TKI (osimertinib). PDXs with spatial heterogeneity in MET pathway activation (LAT001_6B and LAT001_9B), PDXs with temporal heterogeneity in MET pathway activation (LAT006_2B and LAT006_0118) and an additional validation PDX (LAT015_6B) were treated with vehicle, osimertinib, savolitinib, and osimertinib plus savolitinib combination followed by assessment of efficacy and identification of predictive markers.</p

FIGURE 4 from Functional Heterogeneity in MET Pathway Activation in PDX Models of Osimertinib-resistant EGFR-driven Lung Cancer

Heterogeneity in MET polysomy and MET amplification in osimertinib-resistant EGFR-mutant NSCLC. A, Representative phospho-MET IHC (several are reused from Fig. 2D), MET FISH images and MET FISH scoring from PDXs with MET polysomy. B, Representative phospho-MET IHC, MET FISH images and MET FISH scoring from longitudinally collected tumor samples from patient LAT006 at first progression on osimertinib, second progression after osimertinib rechallenge, and upon further progression on chemoimmunotherapy. Scale bars, 50 µm.</p

FIGURE 5 from Functional Heterogeneity in MET Pathway Activation in PDX Models of Osimertinib-resistant EGFR-driven Lung Cancer

Phospho-MET expression is an indicator of MET activity post-osimertinib treatment; and proposed clinical flow diagram for treating EGFR-mutant NSCLC with evidence of MET pathway activation after osimertinib resistance. Representative phospho-MET IHC, MET FISH images and MET FISH scoring from pre- and post-osimertinib resistant tumors from patient LAT028 (multiple spatially heterogenous post-osimertinib resistant tumors shown; A) and from patient LAT021 (B). Scale bars, 50 µm. C, Clinical flow diagram for osimertinib-resistant EGFR-mutant NSCLC with evidence of MET pathway activation.</p

FIGURE 2 from Functional Heterogeneity in MET Pathway Activation in PDX Models of Osimertinib-resistant EGFR-driven Lung Cancer

Efficacy and determinants of response to osimertinib and savolitinib combination among osimertinib-resistant EGFR-mutant NSCLC PDX models with spatially and temporally heterogenous MET pathway activation. Tumor growth inhibition studies in MET polysomy (A) and MET amplified (B) PDXs. Dashed vertical lines delineate when treatment was stopped. Asterisks signify statistical significance between osimertinib and savolitinib combination and osimertinib alone treatment arms. P values were calculated by t test. P values C, Association between response to osimertinib and savolitinib combination and IHC features (phospho-MET, c-MET), copy number and FISH parameters (number of MET copies and MET/CEP7 ratio). Response is defined as >25 days until reaching tumor size endpoint in osimertinib and savolitinib combination compared with osimertinib treatment alone. Individual circles represent a unique tumor for each represented PDX model. D, Representative c-MET and phospho-MET IHC images of PDX tumors with and without response to osimertinib and savolitinib combination. Scale bars, 50 µm.</p

FIGURE 3 from Functional Heterogeneity in MET Pathway Activation in PDX Models of Osimertinib-resistant EGFR-driven Lung Cancer

Osimertinib and savolitinib combination suppresses AKT signaling in MET amplified osimertinib-resistant EGFR-mutant NSCLC PDXs. EGFR and MET pathway protein expression in MET amplified (A) and MET polysomy (B) LAT006 PDXs treated with either vehicle, osimertinib, savolitinib, and osimertinib plus savolitinib. Bar graphs show the relative quantification of phosphorylated proteins normalized to total protein expression in MET amplified (C) and MET polysomy (D) LAT006 PDXs.</p

Supplementary Table from Functional Heterogeneity in MET Pathway Activation in PDX Models of Osimertinib-resistant EGFR-driven Lung Cancer

Supplementary Table provides clinical, molecular and passaging details for the PDXs generated in this study</p