Study shows efficacy and safety of cytisine as a smoking cessation therapy

Reviewed by Emily Henderson, B.Sc.Jul 28 2022

Research published in the Journal of Thoracic Oncology (JTO) shows cytisine may be a safe and effective smoking cessation therapy in lung cancer screening volunteers. JTO is the official journal of the International Association for the Study of Lung Cancer. The full study can be accessed here: https://www.jto.org/article/S1556-0864(22)00346-X/fulltext.

Cytisine is a plant-based alkaloid that is extracted from Cytisus laburnum and is a selective partial agonist nicotinic acetylcholine receptors and has been licensed and used for smoking cessation in Europe since the 1960s. Current FDA-approved drugs for smoking cessation in the U.S. are varenicline and bupropion. In 2018, the Food and Drug Administration approved a trial in the United States to test the efficacy of cytisine.

To determine whether cytisine is a safe and effective smoking cessation therapy during low-dose computed tomography (LDCT) screening, researchers led by Dr. Ugo Pastorino, Fondazione IRCCS Istituto Nazionale dei Tumori, in Milan, Italy, established the single center, randomized controlled trial called Screening and Multiple Intervention on Lung Epidemics (SMILE) study.

Pastorino and colleagues randomized 869 current smokers--470 (54%) were assigned to the intervention arm including cytisine, and 399 (46%) were assigned to the control arm. The primary outcome was continuous smoking abstinence at 12 months, biochemically verified through carbon monoxide measurement.

At the 12-month follow-up, the quit rate was 32.1% (151 participants) in the intervention arm and 7.3% (29 participants) in the control arm. The adjusted odds ratio (OR) of continuous abstinence was 7.2 (95% confidence interval, 4.6 to 11.2). Self-reported adverse events occurred more frequently in the intervention arm (399 events among 196 participants) than in the control arm.

The efficacy and safety observed in the SMILE RCT indicate that cytisine, a very low-cost medication, is a useful treatment option for smoking cessation and a feasible strategy to improve LDCT screening outcomes with a potential benefit for all-cause mortality."

Dr. Ugo Pastorino, Fondazione IRCCS Istituto Nazionale dei Tumori, in Milan, Italy