Nabi Biopharmaceuticals Successfully Completes NicVAX Phase 2b Trial

Armen Hareyan's picture

Nabi Biopharmaceuticals successfully completed Phase 2b trial of NicVAX (Nicotine Conjugate Vaccine), the company's innovative and proprietary investigational vaccine being developed to treat nicotine addiction and prevent smoking relapse. The final 12-month data confirm the highly significant trends seen in the previous data at six and nine months for both smoking cessation and long-term smoking abstinence. These data were presented at 9:45 a.m., EST today at the American Heart Association (AHA) Scientific Sessions 2007 in Orlando, Florida by one of the trial's lead investigators, Dr. Stephen Rennard, Larson Professor of Medicine, University of Nebraska Medical Center.

"I believe data from this trial are very encouraging - for smokers who are trying to quit as well as for the field of smoking cessation vaccines," said Dr. Rennard. "Only a short time ago, it was difficult to find convincing evidence to link anti-nicotine antibody with smoking cessation. This double- blind, placebo-controlled trial has demonstrated a clinical proof of concept. The data show there is a correlation between antibody level and the ability of patients to quit smoking and remain abstinent over long periods of time. This development is key for the field of smoking cessation research and could have a significant impact on how we treat patients with nicotine addiction."

NicVAX Phase 2b Trial: Key Findings in Final 12 Month Data Set

Optimal NicVAX Dose and Schedule Identified for Smoking Cessation and Long-Term Abstinence

A statistically significant number of patients treated with the NicVAX optimal dose (400 micrograms) and schedule (Schedule 2) were able to quit smoking and remained abstinent over the long-term:

* 12-Month continuous abstinence: NicVAX 400 micrograms, Schedule 2 = 16% (8/51), Placebo=6% (6/100), p<0.038 (intent to treat population)

* 12-Month continuous abstinence: NicVAX 200 micrograms, Schedule 2 = 14% (7/50), Placebo=6% (6/100), p<0.056 (intent to treat population)

* For the final 12-month data analysis, this response was calculated using total time after the Target Quit Date, rather than the general study week (which was used in interim data analyses). This conservative and stringent statistical approach yielded statistically significant findings even after a full year.

Anti-Nicotine Antibody Levels Drive Long-Term Smoking Abstinence


* The rate of smoking cessation and ability to achieve long-term abstinence in treated patients was correlated with level of anti-nicotine antibodies at critical time points: The high antibody responder group (top 30% of antibody responders) showed continuous abstinence rates almost three times those of placebo at 12 months.

* These high antibody responders continued to show statistically significant abstinence at 12 months: NicVAX= 16% (10/61) vs. Placebo= 6% (6/100), p<0.032

* Subjects in the therapeutic effect window show a >30% likelihood of achieving at least four months of smoking abstinence and remaining entirely abstinent through 12 months following the first administration of NicVAX.

Overall Health Benefit - High Antibody Responders Smoked Fewer Cigarettes

Those patients in the NicVAX group who continued to smoke but who also showed a high antibody response (top third) showed a statistically significant reduction in cigarettes smoked over the full 12 months compared to placebo (p<0.022):

* Using a repeated measures model, vaccinated smokers who failed to quit but showed a high antibody response smoked a median of only 10 cigarettes per day while in the study, compared to their own baseline values of 20 cigarettes per day before treatment.

Importantly, there was no evidence of compensatory smoking or increase in withdrawal symptoms observed in NicVAX patients at any stage of the 12- month trial. NicVAX continued to be well-tolerated with the placebo and NicVAX dose groups showing comparable adverse event profiles at each stage of the clinical study.

"We are excited and greatly encouraged by the significant learning which has come from this first efficacy trial of NicVAX." said Dr. Leslie Hudson, Interim President and Chief Executive Officer of Nabi. "It is important to note that we have seen success in each of the critical parameters of this trial; we know the dimensions of the therapeutic antibody window which will drive continuous abstinence out to a full year, we know the relationship between the psychological and biochemical drives to quit and remain abstinent and, most importantly, we believe we now have the insight to drive a higher rate of response. We will use these encouraging final data to advance our NicVAX partnership discussions and to determine the optimal design for the next step in our clinical trial efforts for this important primary care product candidate."

About the Phase 2b Study

The Phase 2b study was a double-blind, placebo-controlled and dose-ranging study comprised of 301 patients designed to establish proof of concept and the optimal dose for the Phase 3 program. This study was designed in collaboration with the U.S. Food and Drug Administration and other global regulatory agencies and incorporates the most current clinical trial standards and prevailing protocol design for smoking cessation studies. The trial's primary endpoint is the rate of carbon monoxide (CO)-confirmed, continuous abstinence from smoking during weeks 19-26 after first vaccination. In May 2007, Nabi announced this trial's six-month data, which showed that a statistically significant number of patients with in the high anti-nicotine antibody responder group met the trial's primary endpoint of eight weeks of continuous abstinence between weeks 19-26.