Fig. 1: TWIST1 is overexpressed in patient derived xenografts (PDXs) at the time of MET TKI resistance and can be targeted.

A Schematic diagram for the generation of capmatinib resistant PDXs in mouse model. The tumor from a patient harboring MET exon 14 mutant NSCLC brain metastasis (UW-21 lung) were directly implanted in mice and treated with capmatinib at an equivalent dose of 5 mg/kg animal body weight. The xenografts show complete response after 3-4 weeks of capmatinib treatment. The tumor subsequently regrew after 4–6 weeks. The mice were treated with 4-6 alternate cycle of capmatinib for three weeks each time until tumor was capmatinib resistance. The capmatinib resistant PDX was named UW-21 CR lung. The illustrations were created with BioRender.com. B Western blot demonstrating TWIST1 overexpression in capmatinib resistant PDXs (UW-21 CR lung) compared to their capmatinib sensitive tumor (UW-21 lung). C Western blot demonstrating that MET amplification leads to increased expression of TWIST1 in NSCLC PDXs. Encircled in red boxes are the PDXs with high p-MET. Red asterisk above the cell line lane denotes MET amplified cells. Higher TWIST1 expression in MET amplified PDXs resulted these PDXs resistance to MET TKIs (LNEC: large cell neuroendocrine carcinoma; ADC: adenocarcinoma; SCC: squamous cell carcinoma; UNDIFF: undifferentiated tumor). D Baseline expression of TWIST1 in MET wild type, MET amplified and MET mutated human cell lines. E Silencing of TWIST1 with two distinct shRNAs resulted in growth inhibition in a MET mutant (H1437, H596) or MET amplified (H1993, H1648) cell lines as shown by cell viability assay (Scr, scrambled control for shRNA). F Cell viability assay demonstrating that the TWIST1 inhibitor, harmine has activity in a panel of MET altered NSCLC cells after 72 h of treatment.