Use of the nicotine metabolite ratio as a genetically informed biomarker of response to nicotine patch or varenicline for smoking cessation: a randomised, double-blind placebo-controlled trial

Abstract

Summary Background There is substantial variability in therapeutic response and adverse effects with pharmacotherapies for tobacco dependence. Biomarkers to optimize treatment choice for individual smokers may improve treatment outcomes.Wetested whether a genetically-informed biomarker of nicotine clearance, the nicotine metabolite ratio (NMR; 3’hydroxycotinine/cotinine), predicts response to nicotine patch vs. varenicline for smoking cessation. Methods AnNMR-stratified multicenter, randomized, placebo-controlled clinical trial was conducted from November 2010-September 2013 at 4 sites. Treatment-seeking smokers (1246: 662 slow metabolizers; 584 normal metabolizers) were randomized to 11-weeks of nicotine patch (active patch + placebo pill), varenicline (active pill + placebo patch), or placebo (placebo pill + patch), plus behavioral counseling; an intent-to-treat analysis was conducted. Participants were followed for 12-months following the target quit date.The primary endpoint was biochemically verified 7-day point prevalence abstinence at the end of treatment (EOT) to estimate the pharmacologic effect of treatment by NMR. Secondary outcomes were side-effects, withdrawal symptoms, and 6- and 12-month abstinence rates. ClinicalTrials.govregistration: NCT01314001 Findings In the longitudinal model including all time points, the NMR-by-treatment interaction was significant (ratio of odds ratios (ORR)=1·96; CI=(1·11, 3·46); p=0·02). The results indicate that varenicline was more efficacious than nicotine patch for normal metabolizers, whilethe efficacy was equivalent for slow metabolizers. In cross-sectional analyses, the interaction was significant at EOT (ORR)=1·89; CI=(1·02, 3·45); p=0·04) andat 6-months (ORR=2·07; CI=(1·01, 4·22); p=0·05), but not at 12-months (p=0·14). An NMR-by-treatment interaction showed that slow (vs. normal) metabolizers reported greater overallside-effects severity with vareniclinevs. placebo (β−1·06; CI=(−2·08, −0·03); p=0·044). Interpretation Treating normal metabolizers with varenicline and slow metabolizers with nicotine patchmayoptimize quit rates while minimizing side-effects. Funding National Institutes of Health