RecruitingPhase 2Drug trialOngoing Lung Decline With Age Intensified ResponseThis Phase II, randomized, double-blind, placebo-controlled pilot study will evaluate the effects of fisetin, a senolytic flavonoid compound, on lung function and biomarkers of cellular senescence in older adults aged 60 years and older. Participants will include individuals with a history of at least 10 pack-years of smoking as well as age-matched never-smokers. Forty participants will be randomized to receive either fisetin or placebo using a short-course "hit-and-run" dosing strategy (approximately 20 mg/kg/day orally for 2 consecutive days on Days 1-2 and Days 8-9).