Feasibility and safety of a 4-week AB-free kava intervention among adults who smoke cigarettes and its effects on reducing lung cancer risk biomarkers: a pilot trial

Because of the high prevalence of lung cancer, its poor clinical prognosis, and cigarette smoke being the dominant cause, preventive agents are urgently needed to help reduce lung cancer risk among those with tobacco exposure. Motivated by epidemiological observation, pre-clinical data, and pilot single-arm trial results, AB-free kava (a kava formular of consistent kavalactone composition and free of potentially hepatotoxic flavokavains A and B) may safely prevent cigarette smoke-induced lung cancer. The objective of this study was to evaluate a 4-week AB-free kava intervention among adult smokers for its feasibility, safety, and effects on lung cancer risk biomarkers (urinary 3-methyladenine (3-mA), total nicotine equivalent (TNE)-corrected 3-mA, and plasma 1-(3-pyridyl)-1,4-butanediol (PBD)) via a pilot randomized double-blind placebo-controlled trial. Data were collected during (Week 0, 1, 2, and 4) and after (Week 8 and 12) AB-free kava intervention with nineteen eligible participants enrolled and analyzed (10 in the placebo arm and 9 in the AB-free kava arm). Two participants in the placebo arm experienced liver enzyme elevations, with no elevation observed in the AB-free kava arm. More adverse events (self-addressed) were observed in the placebo arm than in the AB-free kava arm. AB-free kava intervention significantly reduced TNE-corrected 3-mA and showed the trends to reduce urinary 3-mA and plasma PBD. The trial results thus support the feasibility and safety of the 4-week AB-free kava intervention among adults who smoke and preliminarily reveal its efficacy in reducing lung cancer risk, which requires further validation.