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The harm of smoking results mainly from long-term exposure to harmful and potentially harmful constituents (HPHCs) generated by tobacco combustion. Smoking cessation (SC) engenders favorable changes of clinical signs, pathomechanisms, and metabolic processes that together could reduce the harm of smoking-related diseases to a relative risk level approximating that of never-smokers over time. In most SC studies, the main focus is on the quitting rate of the SC program being tested. As there is limited information in the literature on short to multiple long-term functional or biological changes following SC, more data on short to mid-term favorable impacts of SC are needed.
The overall aim of the study was to assess the reversibility of the harm related to smoking over 1 year of continuous smoking abstinence (SA). This has been verified by assessing a set of biomarkers of exposure to HPHCs and a set of biomarkers of effect indicative of multiple pathophysiological pathways underlying the development of smoking-related diseases.
This multiregional (United States, Japan, and Europe), multicenter (42 sites) cohort study consisting of a 1-year SA period in an ambulatory setting was conducted from May 2015 to May 2017. A total of 1184 male and female adult healthy smokers, willing to quit smoking, were enrolled in the study. Nicotine replacement therapy (NRT) was provided for up to 3 months upon the subject’s request. SC counseling and behavioral support were continuously provided. Biomarkers of exposure to HPHCs and biomarkers of effect were assessed in urine and blood at baseline, Month 3, Month 6, and Month 12. Cardiovascular biomarkers of effect included parameters reflecting inflammation (white blood cell), lipid metabolism (high-density lipoprotein cholesterol), endothelial function (soluble intercellular adhesion molecule-1), platelet function (11-dehydrothromboxane B2), oxidative stress (8-epi-prostaglandin F2 alpha), and carbon monoxide exposure (carboxyhemoglobin). Respiratory biomarkers of effect included lung function parameters and cough symptoms. The biomarkers of effect to evaluate genotoxicity (total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol) and xenobiotic metabolism (cytochrome P450 2A6 activity) were also assessed. Continuous SA was verified at each visit following the actual quit date using self-reporting and chemical verification. Safety assessments included adverse events and serious adverse events, body weight, vital signs, spirometry, electrocardiogram, clinical chemistry, hematology and urine analysis safety panel, physical examination, and concomitant medications.
In total, 1184 subjects (50.1% male) were enrolled; 30% of them quit smoking successfully for 1 year. Data analyses of the study results are ongoing and will be published after study completion.
This study provides insights into biological and functional changes and health effects, after continuous SA over 1 year. Study results will be instrumental in assessing novel alternative products to cigarettes considered for tobacco harm reduction strategies.
ClinicalTrials.gov NCT02432729; http://clinicaltrials.gov/ct2/show/NCT02432729 (Archived by WebCite at http://www.webcitation.org/78QxovZrr)
DERR1-10.2196/12138
Cigarette smoking is the leading cause of preventable deaths worldwide and is associated with increased risk of pulmonary disease, cardiovascular disease (CVD), and other serious diseases, such as cancer [
It is widely recognized that the harm associated with smoking results mainly from long-term exposure to the harmful and potentially harmful constituents (HPHCs) contained in cigarette smoke, generated by combustion of tobacco and not from nicotine itself [
Owing to the abundant concurrent processes in disease pathways, there is no single biomarker that is considered as a validated surrogate measure reflecting the biological processes, physiological system, and/or a mechanism of action that is associated with, or actually known to contribute to, smoking-related diseases. Numerous epidemiological studies have shown that most of the smokers who quit smoking benefit from a gradual and significant reduction of harm and risk of smoking-related diseases over time, as SC favorably reverses many of the adverse functional and biological changes associated with smoking [
Despite the substantial amount of SC studies in the literature, the main focus of these studies has been the successful quitting rates as a result of SC treatment rather than on evaluating short- and long-term (up to 1 year and beyond) functional and biological changes in the body upon continuous SA. Given the need for additional data to bridge this evidence gap, providing broader and deeper insights into the clinical benefits upon SC, we conducted a study in adult healthy smokers who were continuously abstinent from smoking for 1 year. The overall aim of our study was to assess the reversibility of smoking-related harm after continuous SA.
Using available epidemiological data reporting quantitative estimates of the association with CVD, respiratory diseases and cancer in smokers and reversibility upon SC within a 1-year time frame, a set of biological and functional parameters, identified as biomarkers of effect and biomarkers of exposure to HPHCs, were selected based on predefined criteria and assessed in this study. Covering multiple pathways involved in the pathogenesis of smoking-related diseases, the selected parameters will provide an overall understanding of how SC triggers favorable changes and the time frame of reversibility from mechanistic pathways that are commonly involved in the onset and progression of smoking-related diseases.
Offering smokers nicotine delivery products, with the potential to reduce the risk of smoking-related diseases, as a replacement for cigarettes is an emerging approach for smoking harm reduction strategy [
To assess reduced risk potential, the Institute of Medicine of the National Academies recommends the use of appropriately designed studies to establish whether the use of novel alternatives to cigarettes, such as heat-not-burn tobacco products or nicotine-containing e-vapor products, reduces exposure to toxicants or induces positive changes in surrogate markers [
This 56-week, multiregional, multicenter, ambulatory study was conducted at 42 sites in the United States, Japan, and Europe, and it is registered at ClinicalTrials.gov (identifier NCT02432729). The institutional review boards or independent ethics committees for each participating institution granted ethical approval. The study followed the principles defined by the International Conference on Harmonization Good Clinical Practice, the Declaration of Helsinki, and other applicable regulations [
Participants recorded their own actual quit date and provided the information to their study clinic. Visits were scheduled on a monthly basis for the duration of the 52-week study (1 year), with biomarker sample collections scheduled for the Month 3, Month 6, and Month 12 visits. The study ended after a 28-day safety follow-up period. SC support, including counseling and behavioral support, was provided throughout the study at scheduled visits and between visits as requested by the subject. Participants were allowed to use NRT to support SC if requested by the subjects. NRT was started any time between the target quit date and 1 week after the actual quit date and was permitted for up to 3 months and 2 weeks. Adverse events were collected at each visit. Participants who smoked after the actual quit date were discontinued from the study.
Study design and timeline. Target quit date (TQD) was within 1-14 days after check out of Visit 2; actual quit date (AQD) was within 14 days after the TQD (grace period with occasional tobacco/nicotine use). Nicotine replacement therapy (NRT) was only permitted for up to three months + two weeks after the start date of NRT, which occurred at any time between the TQD and one week after the AQD. CC: cigarettes; SA: smoking abstinence; V: visit; W: week.
All participants provided written informed consent. The study enrolled healthy adult smokers who were motivated to quit smoking within the next 30 days. Their motivation was assessed using a questionnaire based on the Prochaska stages of change [
A total of 1035 participants who successfully abstained from smoking for at least 2 weeks after the actual quit date were remaining in the study, meaning the study was completed with at least 190 successful quitters.
Inclusion criteria
Informed consent form(s) signed
Age 30 to 65 years (inclusive)
Positive urine cotinine test at both screening and Visit 2 (cut-off ≥200 ng/mL)
Smoking history of at least 10 years before screening
Smoking history of at least 10 cigarettes/day on average in the 12 months preceding screening (as reported by the subject)
Willingness to quit smoking within the next 30 days
Exclusion criteria
Clinically relevant gastrointestinal, renal, hepatic, neurological, hematological, endocrine, oncological, urological, pulmonary, immunological, psychiatric, or cardiovascular disorders or any other conditions that would jeopardize the safety of the participant or affect the validity of the study results
Abnormal findings on physical examination, in the medical history, or in clinical laboratory results deemed clinically relevant by investigators (as per the common terminology criteria for adverse events)
Acute illness (eg, upper-respiratory tract infection and viral infection) requiring treatment within 42 days before enrollment in the study
Use of any prohibited, prescribed, or over-the-counter systemic medications within 42 days of enrollment (except for vitamins, hormonal contraceptives, and hormone replacement therapy)
Forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) <0.7 and FEV1 <80% predicted value at postbronchodilator spirometry
FEV1/FVC <0.75 (postbronchodilator) and reversibility in FEV1 >12% and >200 mL from pre- to postbronchodilator values
Pregnancy or breastfeeding
The main objective of the study was to describe the biological and functional changes in smokers who are continuously abstinent from smoking. The biomarkers of effect, including those associated with CVD, respiratory diseases, xenobiotic metabolism, and genotoxicity, are provided in
The biomarkers of exposure to HPHCs in smokers who continuously abstained from smoking (
The rate of continuous SA was determined at each visit following the actual quit date.
Safety was established by monitoring adverse events, body weight, vital signs, spirometry, electrocardiogram, hematology and clinical chemistry marker panels, urine analysis, physical examination, and concomitant medications. Adverse events were coded according to MedDRA terminology.
Biomarkers of effect.
Variable, effect category | Effect | ||
Lipid metabolism |
High-density lipoprotein cholesterol Low-density lipoprotein cholesterol Apolipoprotein A1 (Apo A1) Apolipoprotein B (Apo B) Apo B/Apo A1 |
||
Inflammation |
White blood cell count High-sensitivity C-reactive protein Homocysteine |
||
Platelet function |
Platelet cell count Fibrinogen 11-dehydrothromboxane B2 (urine) |
||
Oxidative stress |
8-epi-prostaglandin F2 alpha (urine) Myeloperoxidase |
||
Endothelial dysfunction |
Soluble intercellular adhesion molecule-1 Albumin (urine) |
||
Acute cardiovascular effect |
Carboxyhemoglobin |
||
Metabolic syndrome |
Glycosylated hemoglobin |
||
Spirometry |
Forced expiratory volume in one second (FEV1) Forced vital capacity (FVC) FEV1/FVC Forced expiratory flow at 25–75% of the pulmonary volume (FEF25-75) |
||
Lung volume |
Vital capacity Total lung capacity Functional residual capacity Inspiratory capacity Residual volume |
||
Cough |
Cough symptoms (intensity and frequency) Sputum production and bothersome cough symptoms reported in cough questionnaire |
||
Lung sounds analysis |
Computerized multichannel Stethographics and Stethos |
||
Gas transfer |
Carbon monoxide lung diffusion capacity and rate constant |
||
—a |
Cytochrome P450 2A6 activity |
||
— |
Total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (Total NNAL; urine) |
aNot applicable.
Biomarkers of exposure endpoints.
Harmful and potentially harmful constituents | Biomarkers of exposure |
Carbon monoxide | Carbon monoxide in exhaled breath |
Nicotine | Cotinine and nicotine in plasma and nicotine equivalents in urine |
1,3-butadiene | Monohydroxybutenylmercapturic acid |
Acrolein | 3-hydroxypropylmercapturic acid |
Acrylonitrile | 2-cyanoethylmercapturic acid |
Benzo(a)pyrene | 3-hydroxybenzo(a)pyrene |
Pyrene | Total 1-hydroxypyrene |
Crotonaldehyde | 3-hydroxy-1-methylpropylmercapturic acid |
N-nitrosonornicotine | N-nitrosonornicotine |
4-aminobiphenyl | 4-aminobiphenyl |
Benzene | S-phenylmercapturic acid |
1-aminonaphthalene | 1-aminonaphthalene |
2-aminonaphthalene | 2-aminonaphthalene |
o-toluidine | o-toluidine |
Ethylene oxide | 2-hydroxyethylmercapturic acid |
Toluene | S-benzylmercapturic acid |
Full lung function assessments, blood and urine samples for biomarkers of effect, and biomarkers of exposure analyses were conducted at baseline (Visit 2) and at 3 time points during the study (Month 3, Month 6, and Month 12 visits). Cough assessment by visual analog scale and Likert scales (intensity of cough, frequency of cough, and amount of sputum collection) were conducted at baseline (Visit 2) and at 3 time points during the study (Month 3, Month 6, and Month 12 visits). Noncompliance with continuous SA was verified as follows:
At each visit, participants were asked to confirm their continued abstinence from smoking from the actual quit date onward (ie
CO breath test (>10 pm) from Visit 4 onward.
Urine cotinine test at each visit from Visit 10 onward (cotinine test ≥100 ng/ml).
Free cotinine concentration (part of nicotine equivalents) in 24-h urine collected at Visit 11 (free cotinine ≥50 ng/mL).
Socioeconomic status, lifestyle, stage of change [
On the basis of the results of the Lung Health Study and on the 1-year abstinence rates from English smoking treatment services [
Changes from baseline were summarized for the main analysis population, defined by quitters with no major protocol deviations impacting subject availability. Data collected after evidence of noncompliance with continuous abstinence were not included in the analysis. For analysis purposes, the concentrations of free cotinine (≥50 ng/mL) [
A total of 2090 subjects were screened for the study (
The study was completed in May 2017. The results of this study are under evaluation and will be published upon completion of analysis.
Flow chart of study participants.
The approach of our study is unlike other SC studies whose primary objective was to test the efficacy of an SC treatment (ie, drug or behavioral cessation support) [
In this study, the list of biological and functional parameters and biomarkers of exposure to be tested was extensive. This list was carefully selected to provide high-quality evidence for the effect of SA on a variety of HPHCs and the health-related effects of smoking that are reversible upon SC. These endpoints will provide further insights into the risk profile of a smoker following abstention from smoking within a short time frame by examining a collection of logical, empirically coherent, and mutually supportive data from multiple clinical risk components across several biological processes, physiological systems, and mechanisms that are known to contribute to the pathogenesis of smoking-related diseases.
The results of this study may offer a valuable point of reference for future assessments of alternative products in the context of tobacco harm reduction, providing scientific evidence of the potential of alternative products to reduce the risk of harm in smokers within a 1-year time frame when compared with continuing to smoke cigarettes. With this aim, cross-study analyses need to be designed carefully to ensure baseline comparability of quitters with the population of smokers switching to the alternative product. Such a comparative approach is valuable for obtaining data on the risk reduction potential of a product alternative to cigarettes earlier than epidemiological studies, which require long-term assessment to provide data.
The design and approach used in the present study should be considered in light of its limitations. One limitation was related to the difficulty of recruiting smokers who were both willing and motivated to quit smoking, completely and continuously, for 1 year. In addition, the uncontrolled before and after study design and the lack of a control arm with no intervention might require careful interpretation of the outcomes of this study. The results of this study should be interpreted with caution owing to the lack of control of potential confounding factors. Factors such as concomitant medications, lifestyle, and weight increase can cause changes in lipid metabolism and other biochemical processes following SC [
This study was designed to provide an extensive dataset on changes in biomarkers of effect and biomarkers of exposure after 12 months of continuous SA. Therefore, it will provide a comprehensive overview of the beneficial short-term health effects that occur over the course of 1 year in a smoker who ceases smoking. The results from this study will complement existing evidence for the benefits of cessation. In the context of smoking harm reduction, these results may be used as a benchmark for the future evaluation of alternative products to cigarettes and to supplement the existing literature on the biological and functional health effects of SC.
cardiovascular disease
forced expiratory volume in one second
forced vital capacity
harmful and potentially harmful constituent
nicotine replacement therapy
Philip Morris International
Philip Morris International Research & Development
smoking abstinence
smoking cessation
white blood cell
World Health Organization
The authors deeply appreciate the contributions of all investigators and other clinical research staff involved in the study. This study was sponsored by Philip Morris International (PMI). We thank Susan E Cottrell, PhD, and Tarveen Jandoo, MD, MBA, of Edanz Medical Writing for providing medical writing support, and Andrea Donelli, BSc, MAS, for his support in reviewing the publication. Additionally, the authors thank Paul Hession for editorial support.
The study reported in this publication was solely funded by PMI. All authors are (or were) employees of PMI Research & Development (R&D) or worked for PMI R&D under contractual agreements.