A Vaccine against Nicotine for Smoking Cessation: A Randomized Controlled Trial

Background Tobacco dependence is the leading cause of preventable death and disabilities worldwide and nicotine is the main substance responsible for the addiction to tobacco. A vaccine against nicotine was tested in a 6-month randomized, double blind phase II smoking cessation study in 341 smokers with a subsequent 6-month follow-up period. Methodology/Principal Findings 229 subjects were randomized to receive five intramuscular injections of the nicotine vaccine and 112 to receive placebo at monthly intervals. All subjects received individual behavioral smoking cessation counseling. The vaccine was safe, generally well tolerated and highly immunogenic, inducing a 100% antibody responder rate after the first injection. Point prevalence of abstinence at month 2 showed a statistically significant difference between subjects treated with Nicotine-Qβ (47.2%) and placebo (35.1%) (P = 0.036), but continuous abstinence between months 2 and 6 was not significantly different. However, in subgroup analysis of the per-protocol population, the third of subjects with highest antibody levels showed higher continuous abstinence from month 2 until month 6 (56.6%) than placebo treated participants (31.3%) (OR 2.9; P = 0.004) while medium and low antibody levels did not increase abstinence rates. After 12 month, the difference in continuous abstinence rate between subjects on placebo and those with high antibody response was maintained (difference 20.2%, P = 0.012). Conclusions Whereas Nicotine-Qβ did not significantly increase continuous abstinence rates in the intention-to-treat population, subgroup analyses of the per-protocol population suggest that such a vaccination against nicotine can significantly increase continuous abstinence rates in smokers when sufficiently high antibody levels are achieved. Immunotherapy might open a new avenue to the treatment of nicotine addiction. Trial Registration Swiss Medical Registry 2003DR2327; ClinicalTrials.gov NCT00369616

The PI at each site will nominate a Co-Investigator who will assist supervising the study. In addition, each site will have at least one medically qualified person (sub-investigator, study physician) and a study nurse or technician fully dedicated to the study and in charge of the organization, clinical conduct and documentation.

Objectives:
The objectives of this exploratory Phase II trial are • To assess clinical efficacy of NicQb in smokers willing to quit -by determination of 3 months continuous abstinence rate at week 24, based on smoking diaries and urinary cotinine; -by determination of point-prevalence of abstinence during the past 24 hours at monthly intervals, from the target quitting date up to week 24, based on self-reported smoking status and carbon monoxide in exhaled air; -by recording changes in smoking habit, at monthly intervals from the target quitting date up to week 24, based on diaries. • To evaluate safety and tolerability (local and systemic) of NicQb in healthy smokers -by frequent monitoring of clinical signs and symptoms up to week 24 -by assessing smoker's psychological state (craving, withdrawal symptoms, mood) through appropriate questionnaires • To determine immunogenicity of NicQb -by determination of titers and titer profiles of specific anti-nicotine antibodies (Ab) in serum from pre-dose in monthly intervals up to weeks 24, and during an open follow-up phase up to 12 months

Study Design:
This will be a randomized Phase II efficacy and safety study with one dose of NicQb versus placebo, conducted according to a parallel-group, multi-center study design. At the first center starting the trial, the inclusion of subjects will be staggered such that the first 20 subjects must have completed visit 2 (7 days after the first injection) and tolerability shown to be good; then the additional subjects may be included as they are available and eligible. The dose of 100ug NicQb+Alum has been selected based on the results from the Phase I study. The highest dose used in Phase I was 100µg of the vaccine, tested with and without Alum. All doses have been proven to be well tolerated. Therefore, the immunogenicity of the different doses served as a parameter for dose selection. Since the titer of specific anti-nicotine antibodies is expected to be closely related to the efficacy of the vaccine, a dose of 100µg+Alum was chosen based on its early onset and maximal immune response observed in the Phase I study.

Study Subjects:
300 otherwise healthy smokers (defined as adults between 18 and 70 years -male and female -who have been smoking for more than 3 years ≥ 10 and ≤ 40 cigarettes/day), with a Fageström Index of ≥ 5 at screening, and motivated to quit smoking will be enrolled into the study after written informed consent has been obtained Woman of child-bearing potential must use an effective means of contraception up to 12 months after the last dose of the vaccine.
Exclusion criteria: cardiovascular, renal, pulmonary, endocrine, or neurological disorders, ulcers, dermatologic disorders, autoimmune diseases or severe allergies; an active infectious disease (HBV, HCV); a current diagnosis or a history of relevant depressive episodes or of panic attacks, psychosis, bipolar or eating disorders; use of other smoking-cessation treatments, -like bupropion or nicotine-replacement therapywithin 6 months before study enrolment; pregnancy or lactation; abuse of alcohol or other recreational drugs; use of a psychoactive drug (excluding sleeping pills) within one month before enrolment, and regular use of any non-cigarette tobacco product. Significant clinical laboratory findings (blood chemistry, hematology, urinalysis, ECG).

Study Procedures:
Eligible smokers will be randomized to receive either an active NicQb dose of 100µg+Alum (n=200) or indistinguishable placebo injections (n=100), followed after 4, 8, 12 and 16 weeks by respective boost injections. Efficacy will be recorded at the end of the study after 6 months for continuous abstinence, and monthly during the study after the prime dose for point prevalence abstinence and changes in smoking habits.
Target quitting date (TQD) will be at Visit 4, on the day of the second injection (i.e. 4 weeks after the first injection). Starting one week before TQD participants will attend brief individual counseling sessions for smoking cessation. Smoking habits will be recorded based on diaries. Questionnaires to assess craving and withdrawal symptoms including mood (signs of depression) will be filled out. Blood samples will be taken for routine clinical laboratory, for Ab titer determinations, and a urine sample will be obtained for measuring cotinine levels.
There will be a screening visit, 4 treatment application visits for the vaccine or placebo injections, each followed by a safety check-up one week later. Additionally, there will be 6 visits during the double-blind phase of the trial for the assessment of efficacy parameters and/or brief counseling. After completion of the double-blind 6-months trial phase the study subjects are requested to return for additional follow-up visits at 9 and 12 months after the prime dose for additional blood sampling to monitor Ab titers and to obtain information on current smoking habits. Those visit results will not enter into the primary efficacy evaluation but serve exploratory purposes regarding long-term efficacy and pharmacodynamics.

Route of Administration:
The study drug will be injected by the intramuscular (i.m.) route. The injection volume will be 2ml including the adjuvant which is added to Qb prior to injection. The volume and mode of administration will be optimized for further clinical development. The injection site for the prime dose will be the right deltoid muscle and only when necessary changed to the gluteal muscle. Alternating sides will be used for the boost injections.

Comparator:
Placebo, PBS buffer Study Endpoints: • Clinical efficacy: • Continuous abstinence is assessed at 6 months (week 24) after the prime dose and is defined as abstinence during a 3 months period starting at Visit 13 (week 12) till Visit 18 (week 24). Evaluation is based on self-reported number of cigarettes smoked during that time interval based on diaries, and supported by urinary cotinine and exhaled carbon monoxide determined on the occasion of the respective visits. • Point-prevalence of abstinence is determined monthly up to 6 months after the prime dose, by reported non-smoking status for 24 hours on the day of assessment, and confirmed by a carbon monoxide concentration in expired air of 10ppm or less • Changes in smoking habits are recorded monthly up to 6 months after the prime dose, by self-reported number of cigarettes smoked (diary) and possible

Confidential
Page 8 / 10 CYT002-NicQb 02 Clinical Trial Protocol Synopsis Working document including final Study Protocol of 27-Jul-2003, Amendment I of 02-Oct-2003, Amendment II of 04-Dec-2003and Amendment III of 18-May-2004and Amendment IV of 09-Jun-2004 switches in brand; these data will be compared to a baseline recording which starts two weeks before the first injection.
• Safety and tolerability is assessed through systematic collection of vital signs, standard clinical laboratory exams (hematology, blood chemistry, urinalysis and ECG) and all reported symptoms in all subjects. Craving and withdrawal symptoms including mood will be assessed through appropriate questionnaires. • Immunogenicity will be assessed in all subjects by measuring anti-nicotine Ab titers in serum from pre-dose at monthly intervals up to 6 months after the prime dose, and will be followed up in all subjects during an open follow-up period up to 12 months after the prime dose. Studies with nicotine replacement therapy and bupropione have shown statistically significant separation between active and placebo at 6 and 12 months follow-up in the range of 10% -20%.
Since this Phase II study should lead to a clinical proof of concept (efficacy in smoking cessation) it is powered to detect at least a 15% difference from placebo in 3-months continuous abstinence rate assessed at 6 months after the prime vaccination, with a statistical significance of p<0.05 at a power of 90%. With a 2:1 ratio of subjects on active drug : placebo, the trial will require 300 subjects to participate. All subjects that have received the prime dose will be eligible for the intent-to-treat analysis for efficacy.
Considering the exploratory nature of this Phase II study additional evaluations may be considered driven by the results, since very little is known about the inter-subject variability of responses to the vaccine and even less about the clinical outcome and its correlation with Ab titers.

Total Blood Volume per Subject:
200ml within one year (80ml during the 1 st month, 100ml during 2 nd to 6 th month, 20ml during 7 th to 12 th month.