NGS revealed an EML4-ALK fusion (E6:A20) with a mutation allelic frequency (MAF) of 0.1% in the patient’s plasma ctDNA...The patient was then switched from crizotinib to brigatinib at a dose of 90 mg in the first week and 180 mg thereafter. The patient achieved a complete response (CR) for the lung lesion and a PR for the brain lesions...