Despite the lack of standardized guidelines on ALK TKI washout periods and institutional practice differences, the team initiated alectinib relatively early on after the resolution of pneumonitis due to the high disease burden of the patient, the uniquely rapid reversal of hypoxia and pulmonary infiltrates, inpatient monitoring for immediate toxicities, and the lower pneumonitis risk of alectinib. This evidence concerns the gene ALK and pneumonitis.