Efficacy of the nicotine vaccine 3'-AmNic-rEPA (NicVAX) co-administered with varenicline and counselling for smoking cessation: a randomized placebo-controlled trial.

BACKGROUND AND AIMS: Nicotine vaccination has been proposed as a possible treatment to aid smoking cessation. First efficacy results of the nicotine vaccine 3'-AmNic-rEPA (NicVAX) showed that only a subgroup of the top 30% antibody responders achieved higher abstinence rates than placebo. The present study examined the efficacy of adding NicVAX versus placebo to varenicline and behavioural support as an aid in smoking cessation and relapse prevention. DESIGN: Randomized placebo-controlled trial. SETTING: Two research centres (Maastricht University Medical Centre and Slotervaart Hospital) in the Netherlands. PARTICIPANTS: A total of 558 smokers were assigned randomly to six injections with NicVAX (n = 278) or placebo (n = 280) both co-administered with open label varenicline and behavioural support. MEASURES: Outcomes were prolonged carbon monoxide-validated abstinence from weeks 9 to 52 (primary) and weeks 37 to 52 (secondary). We also performed a pre-planned subgroup analysis in the top 30% antibody responders. FINDINGS: There was no difference in abstinence rates between NicVAX and placebo from weeks 9 to 52 [27.7 versus 30.0%, odds ratio (OR) = 0.89, 95% confidence interval (CI) = 0.62-1.29] or weeks 37 to 52 (33.8 versus 33.2%, OR = 1.03, 95% CI = 0.73-1.46). The top 30% antibody responders, compared to the placebo group, showed a non-significant tendency towards higher abstinence rates from weeks 37 to 52 (42.2 versus 33.2%, OR = 1.47, 95% CI = 0.89-2.42). CONCLUSION: The nicotine vaccine, NicVAX, does not appear to improve the chances of stopping smoking when given in addition to varenicline and behavioural support.