What Is Heat-Not-Burn?

The Science Behind Heat-Not-Burn

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“PMI is conducting research on an electronically heated tobacco product, referred to as IQOS tobacco heating system.”

Philip Morris International has completed a broad range of laboratory and clinical studies on IQOS tobacco heating system, a heat-not-burn tobacco product, as recommended by FDA’s Guidance. PMI applications to FDA in December 2016 seeking FDA review of the science presented herein and authorization to market IQOS in the U.S. as a Modified Risk Tobacco Product. FDA has not, however, granted a marketing order to PMI for an MRTP or determined the data to be sufficient to prove the product reduces the risk.


“PMI is conducting research on an electronically heated tobacco product, referred to as IQOS tobacco heating system.”

Philip Morris International has completed a broad range of laboratory and clinical studies on IQOS tobacco heating system, a heat-not-burn tobacco product, as recommended by FDA’s Guidance. PMI submitted applications to FDA in December 2016 seeking FDA review of the science presented herein and authorization to market IQOS in the U.S. as a Modified Risk Tobacco Product. FDA has not, however, granted a marketing order to PMI for an MRTP or determined the data to be sufficient to prove the product reduces the risk.

IQOS: Results Summary Laboratory Studies

The levels of harmful or potentially harmful constituents (HPHCs) required to be reported to FDA were measured in the aerosol generated by IQOS and are over 90% lower, on average, than those in cigarette smoke from a 3R4F reference cigarette.1 Similarly, the levels of chemicals classified by the International Agency for Research on Cancer (IARC) as Group 1 carcinogens are reduced on average by more than 95% compared to a reference cigarette.

The table comparing the levels of HPHCs found in the aerosol of IQOS with the levels found in smoke from a reference cigarette based on analyses performed by Labstat International ULC, an independent contract research organization, is available here.

What is heat-not-burn? - The Science Behind Heat-Not-Burn - 90% Reduction FDA 95% Reduction Carcinogens

Toxicological studies conducted in laboratory models indicate that IQOS aerosol has the potential to be less toxic than cigarette smoke. For example, in an in vivo study designed to mimic the effect of switching from cigarette smoke to IQOS aerosol, the exposure to IQOS aerosol led to reduced exposure to the HPHCs tested, as well as reduced impact on biological mechanisms and disease endpoints associated with chronic obstructive pulmonary disease (COPD) and cardiovascular disease (CVD).2

What is heat-not-burn? - The Science Behind Heat-Not-Burn - Disease Endpoint for CVD and COPD

Clinical Studies

Three-­month clinical trials carried out in the U.S. and Japan showed that smokers who switched to IQOS inhaled reduced levels of 15 harmful chemicals compared to smokers who continued to smoke. The reduction in exposure to HPHCs measured in smokers who switched to IQOS approached the effect observed in smokers who quit smoking for the duration of the study.

Overall, product satisfaction and measured nicotine uptake were comparable to a cigarette, indicating that IQOS may be a viable alternative for adult smokers. The chart below shows the results for four primary biomarkers of exposure to HPHCs.

What is heat-not-burn? - The Science Behind Heat-Not-Burn - Carbon Monoxide - COHb(%)
What is heat-not-burn? - The Science Behind Heat-Not-Burn - Benzene - S-PMS (pg/mg creatinine)
What is heat-not-burn? - The Science Behind Heat-Not-Burn - Acrolein - 3-HPMA (ng.mg creatinine)
What is heat-not-burn? - The Science Behind Heat-Not-Burn - 1,3-Butadiene - MHBMA (pg/mg creatinine)
What is heat-not-burn? - The Science Behind Heat-Not-Burn - Legend for Chart on Four Primary Biomarkers of Exposure to HPHCs

The following chart shows the reduction in fifteen biomarkers of exposure to HPHCs:

What is heat-not-burn? - The Science Behind Heat-Not-Burn - % Reduction in Biomarkers of Exposure After Switching for Three Months

ClinicalTrials.gov Identifier: NCT01989156 | Results from a clinical trial conducted in the U.S. showing four biomarkers of exposure to HPHCs for adult smokers who continued to smoke, quit smoking, and switched to IQOS over a 5-day period in confinement followed by 85 days in an ambulatory setting.

Learn more about PMI’s clinical assessment program here.

Perception and Behavior Assessment

Premarket assessments show very little interest in IQOS among adult never-smokers and former smokers, and substantial potential for full switching among adult smokers.

Less than 6.4% of adult former smokers and less than 1.1% of adult never-smokers (including young adult never-smokers below the age of 25) expressed an intention to use IQOS, while a significant proportion of adult smokers — between 20% and 39% — intended to use IQOS, depending on the type of tested materials and modified risk message.

Premarket data gathered in the U.S. is corroborated by postmarket data collected in countries where IQOS is available to consumers. In Japan, 68% of IQOS purchasers have fully switched to the heated tobacco category as of December 2017. In other countries, a full or predominant switching rate exceeded 60% among IQOS users. PMI estimates that almost 5 million adult smokers have quit smoking and use IQOS exclusively.

The chart below shows the switching rate in different countries:

What is heat-not-burn? - The Science Behind Heat-Not-Burn - Exclusive and Predominant User Share

Learn more about PMI’s perception and behavior assessment here.

1. Average yield reductions of an investigational variant of IQOS compared to the 3R4F reference cigarette, calculated as an average of the reductions of individual HPHCs, which could be reliably quantified in the study. Aerosol was collected with Intense Health Canada’s Smoking Regime. All yields were taken on a mass-per-stick basis. Reduction calculations exclude nicotine.

2. Phillips et al., An 8-Month Systems Toxicology Inhalation/Cessation Study in Apoe-/- Mice to Investigate Cardiovascular and Respiratory Exposure Effects of a Candidate Modified Risk Tobacco Product, THS 2.2, Compared with Conventional Cigarettes. Toxicological Sciences 2016, 149(2):411-432. doi: 10.1093/toxsci/kfv243.

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