A Comprehensive Evaluation of Tobacco-Flavored vs. Non-Tobacco Flavored E-cigarettes on Smoking Behavior - PROJECT SUMMARY: Studies critically examining the cost-benefit of electronic cigarette (EC) flavors on smoking are urgently needed as FDA is making sweeping and impactful regulatory decisions without this important information. Surprisingly, no independent, long-term, randomized clinical trial has experimentally examined the impact of non-tobacco flavored vs. tobacco flavored ECs on product uptake, sustained use, and complete switching. While the National Academies of Science, Engineering, and Medicine concluded that ECs are likely to be far less harmful than combustible cigarettes, more than 1 million EC products have been banned since 2020, significantly narrowing the marketplace. According to the US FDA, a key reason for the removal of these products was the significant rise in youth vaping, often with flavored ECs. Indeed, the FDA decisions cited a failure of manufacturers to provide sufficient evidence demonstrating that the benefits to adult smokers outweighed the “documented risks to youth,” suggesting that the significant rise in youth vaping significantly tipped the scales a priori in the direction of restricting EC flavors. The current restricted legal EC marketplace may reduce youth vaping but may inadvertently reduce the ability of ECs to compete successfully with conventional cigarettes, reducing adult smokers’ trial and use of e-cigarettes for switching. FDA requires more robust and definitive studies evaluating the benefit of EC flavors, if any, to adult smokers. To provide the needed scientific evidence, we propose a nationwide randomized clinical trial to determine the impact of EC flavors on 1) product uptake and appeal, 2) cigarette craving, symptoms, and dependence, and 3) smoking behavior, including sustained and complete switching from cigarettes to ECs. We will also utilize combination nicotine replacement therapy (NRT, patch and lozenge) as an FDA-approved comparator to determine the potential increased benefit (or not) of EC vs NRT on tobacco use behavior. Smokers (N=1,500) will be randomized to a) preferred flavor EC (PEC); b) tobacco flavor EC (TEC); or c) combination NRT. Products will be provided at no cost for 14 weeks (2-week trial before switch date, 12 weeks of use following switch date). PEC participants will be provided their preferred flavor(s) and able to change flavors throughout the 14 weeks. Changes in smoking will be biochemically confirmed via remote exhaled carbon monoxide reading at 12 weeks (end of product provision) and 26 weeks after the switch date. This significant and innovative study will be the first to provide the FDA with critical and definitive information as to the impact of EC flavors on tobacco use among adult smokers. With expertise conducting nationwide, large- scale EC and NRT trial research, our team is uniquely suited to conduct this investigation. If our study demonstrates no significant improvements in switching with flavored EC use, then the continued sale of these products is likely indefensible; however, if improvements are significant, these findings will provide a critical counterweight to the current FDA regulations and aid future decision making.