EGFR and lung adenocarcinoma: Here we describe a rare case of an advanced-stage lung adenocarcinoma patient with brain metastases (BM) harboring EGFR exon 20 insertion mutation who responded to 1st-line PD-1 inhibitor sintilimab plus chemotherapy (pemetrexed and carboplatin), with a continuous partial response both cranial and extra-cranial and progress free survival beyond 18 months.