Ongoing Research of Cytisinicline for Addiction

A Multicenter, Double-Blind, Randomized, Placebo-Controlled Phase 2b Trial of Cytisinicline in Adult Smokers

This Phase 2b trial was conducted in the US to assess various dosing schedules of cytisinicline in approximately 254 smokers. It evaluated efficacy based on the overall reduction in the number of cigarettes smoked during the various study treatment doses and schedules. It also evaluated compliance and safety profiles, compared to the respective placebo arms. This dose-finding study resulted in identification of the 3 mg, 3 times daily dosing regimen to be used in future cytisinicline Phase 3 trials.


ORCA-1 Program Infographic. Click image to enlarge.

Data Results

  • Statistically significant quit rates demonstrated at both end of treatment and weeks 5 through 8 (the FDA approvable endpoint)
  • Adherence to study treatment was 98% in the 3.0 mg TID arm
  • Cytisinicline was well-tolerated with no serious adverse events reported
  • 3.0 mg dose with TID administration selected to move forward to Phase 3 development

Click image to enlarge.

Characteristic3.0 mg CYT
P Value
Reduction in Expired CO180%38%p = 0.003
4 Week Abstinence250%10%p < 0.001
Continuous Abstinence (Weeks 5-8)330%8%p = 0.005
  1. Average % reduction expired CO from Baseline by Day 26
  2. CO-verified 7-day point-prevalence abstinence rates at end of treatment
  3. Biochemically confirmed  on Day 26 and weeks 5, 6, 7, & 8 (no cigarettes smoked and expired CO<10 ppm)


Most commonly reported (>5%) side effects from ORCA-1:

Adverse Event 3.0 mg TID
Pooled Cytisinicline
At least 1 AE 46%46%47%
Upper Respiratory Tract Infections6%6%14%
Abnormal Dreams6%9%2%
  • Cytisinicline was well-tolerated across all treatment groups
  • Overall low incidence of adverse events
  • No serious or severe adverse events reported

Study Design

This six-arm, multi-center, double-blind, randomized, placebo-controlled, Phase 2b study was conducted in the US. The study was double-blinded to dose but not to the administration schedule. Subjects provided a quit date 5-7 days from randomization. Study treatment started the day after randomization such that study treatment was initiated prior to the quit date.

Demographics were similar between schedules and for treatment arms in gender, age, years of prior smoking, and number of previous quit attempts. At baseline, subjects in the study reported smoking a median of 20 cigarettes per day. ORCA-1 was initiated in October 2018 and enrolled 254 smokers at eight centers across the United States.


ORCA-1 Program Study Design.
Click image to enlarge.

ORCA-1 Trial Locations

ORCA-1 was conducted at the following locations in the US: