The role of S100A9 in brain metastesis in EGFR-mutant lung cancer

Metastatic relapse from treatment failure has been a formidable challenge to finding a cure for EGFR-mutant lung cancer. Metastasis to the brain is a severe complication for 45% of patients with EGFR-mutant lung cancer that drastically reduces their quality of life and survival. Here, we demonstrate that genetic inhibition of S100A9, ALDH1A1, RAR, or pharmacological inhibition of the RA pathway using pan-RAR inhibitors significantly reduces brain relapse from osimertinib-refractory cancer cells. Our study has therefore revealed a novel S100A9-ALDH1A1-RA signaling axis in the EGFR-mutant lung cancer cells that drives osimertinib-refractory metastatic brain relapse and identified a potential vulnerability in lung cancer cells that can be therapeutically targeted to prolong progression-free survival in EGFR-mutant lung cancer patients. Overall design: RNA-seq of brain metatstatic derivatives of PC9 and H1650 cell lines.