An analysis of 48 paired pretreatment and posttreatment tumor samples showed augmented HER3 expression in EGFR‐mutant tumors with acquired resistance to EGFR‐TKIs343 and that EGFR inhibition increased membrane expression of HER3 and led to enhanced efficacy of HER3‐DXd,344 thus supporting the rational combination of osimertinib and HER3‐DXd in EGFR‐mutant NSCLC. Here, EGFR is linked to non-small cell lung carcinoma.