A 26-week Extension of the ZRHR-ERS-09-US Study Evaluating Biological and Functional Changes in Healthy Smokers After Switching to THS 2.2

The ZRHR-ERS-09-EXT-US study is a 26-week extension of the original study ZRHR-ERS-09-US. The subjects in the Full Analysis Set - As Exposed (FAS-EX) included subjects for combined analyses from the original six month study (ZRHR-ERS-09-US ) who did not enter the extension study (ZRHR-ERS-09-EXT-US). This study was conducted as a separate investigation, as a follow-up of the randomized exposure period of the original study, extending the exposure from Week 26 (Visit 10 \[V10\]) to Week 52 (Visit 16 \[V16\]), and using the same sites. Subjects continued to use the product they were randomized to in the original study ZRHR-ERS-09-US (THS 2.2 arm or CC arm).