Milestones in Tobacco Heating System Research

What are the key research takeaways for THS?

Each of the conclusions from our research is important, but the finding that THS doesn’t burn tobacco (and thus, doesn’t produce smoke) is critical as a foundation of all our other research. Almost equally foundational is the fact that THS emits, on average, 95% lower levels of harmful chemicals compared with cigarettes. 

Together, these findings demonstrate how different THS is from cigarettes. When smokers puff on a cigarette, the temperature reaches more than 800°C at the tip, which results in burning the tobacco and creating smoke, which contains high levels of toxicants. 

However, the tobacco in THS is heated to a much lower temperature, and no combustion takes place. So, no smoke is created, and much lower levels of harmful chemicals are emitted. In addition, the lower levels of harmful chemicals in THS aerosol lead to other observable differences between THS and cigarettes, and these are further studied in other areas of our smoke-free product assessment program. 

 

How does the evidence of reduced emissions relate to other conclusions from PMI’s assessment program?

PMI’s assessment program involves a number of different steps in addition to aerosol research, including toxicology, clinical studies, perception and behavior research, and long-term studies. Each of these steps builds up the picture of lower harm from THS compared with cigarettes. As we have seen, aerosol research demonstrated that THS does not produce smoke. Following this, toxicology studies have shown that the absence of combustion leads to lower toxicity on cells from the THS aerosol, compared with cigarette smoke. 

Some of the most important findings from these studies demonstrate that the levels of selected toxicants in THS aerosols were, on average, 95% lower than those found in cigarette smoke. On top of this, PMI’s research has demonstrated that THS aerosol contains fewer chemicals than cigarette smoke, and that, although some of the chemicals in THS aerosol are genotoxic or cytotoxic, they are present in very low levels. 

 

How do conclusions based on laboratory research translate to clinical study results? 

There are two main outcomes from our clinical program, which are aligned with the results of our chemical analysis and with our toxicology data.

1. We see a reduction in exposure to harmful chemicals for participants who switch to THS as compared with those who continue to smoke. 
2. And we see a reduction in levels of biomarkers of potential harm (BoPH) in participants who switch to THS as compared with those who continue to smoke.

We conduct a wide range of clinical studies with the help of contract research organizations, including interventional studies and cross-sectional studies.  

Clinical studies measuring biomarkers associated with exposure to chemicals found in cigarette smoke and THS aerosol show that levels of these chemicals in the body are significantly reduced with THS use compared with continued smoking. In fact, the levels with THS were almost the same as those in people who quit tobacco and nicotine altogether.

Research measuring biomarkers of potential harm for smoking-related diseases, such as cardiovascular disease, chronic obstructive pulmonary disease, and cancer, have also shown positive results. Smokers who switched completely from cigarettes to THS saw improvements in biomarkers of disease, along the lines of those seen in smokers who quit altogether. 

These studies also showed that, for THS users who also smoked cigarettes, the fewer cigarettes smoked, the more positive the results. This illustrates the importance of switching completely in order to see the greatest benefit.

It is important to note that THS is not risk free and contains nicotine which is addictive, but based on the available science to date presents a better choice for adults smokers who would otherwise continue to smoke. 

 

Based on PMI’s research, can we expect to see a positive impact on public health? 

Harm reduction has two parts: 

• The smoke-free product has to be scientifically substantiated to have lower risk of harm than cigarette smoking. 
• Existing adult smokers have to switch to the smoke-free product at scale while the amount of unintended use (including people under legal age, former and never smokers) should be minimized.  

We have already seen, from the results of PMI’s aerosol, toxicology, and clinical studies, that our smoke-free products meet the first part of this equation—THS use shows a potential to lower the risk of harm compared with cigarettes smoking.

However, to have a positive impact on public health, we also need the second part of that harm reduction equation—we need to confirm that existing adult smokers who would otherwise continue to smoke will switch at scale. This has been demonstrated in separate studies in Germany, Italy, Japan, South Korea, Switzerland, and the U.S. These studies found that, not only do a percentage of existing smokers switch from cigarettes to THS, but also that total tobacco product consumption among the study groups did not increase. This means that smokers are, on average, not adding THS use on top of smoking but are switching from smoking to THS use.

There is also evidence from multi-country perception and behavior studies that smokers are more likely to switch completely to THS when they are aware that THS presents a lower risk of harm than continued smoking. This indicates that providing accurate and nonmisleading information to adult smokers can facilitate switching, and thus availability of this information can increase the prospect of long-term positive impact on public health.

 

Are we seeing a long-term impact on public health from smoke-free products? 

It is important to remember that smoke-free products are relatively novel, for example, THS has only been commercially available for around 10 years and therefore it is still early to assess if a large-scale public health change has emerged. 

However, studies in Japan, where THS was introduced in 2014, found that in the years 2016 to 2022, the rate of cigarette smoking continued to decrease (at an accelerated pace), while the use of smoke-free products increased. Even more interesting is that smoke-free product use among nonsmokers, as well as the number of THS users moving back to cigarette smoking, were very low over this period. This suggests that the growth in smoke-free product usage was largely coming from adult smokers who would otherwise have continued to smoke switching to THS. 

 

What research studies are coming next from PMI?

PMI is currently conducting clinical studies to further understand the potential that THS could play in lowering the risk of harm from smoking. One of these is a cross-sectional, multi-country study to see if switching from cigarettes to THS reduces exposure to key toxicants, oxidative stress, and inflammation. 

PMI has also recently completed a clinical trial examining nine biomarkers in longer-term smokers who switched completely to THS use for 2 years, compared with those who continued to smoke cigarettes. Results showed that switching was associated with favorable differences in biomarkers related to biological pathways impacted by cigarette smoke (such as inflammation and oxygen transport), as well as with better cardiovascular and respiratory function compared with current smokers. 

The study also provided some of the first evidence that arterial elasticity—the decrease in which is a sign of atherosclerosis—was greater in THS users than in smokers. 

Based on the totality of evidence to date, THS has the potential to reduce the risk of smoking-related disease for those adults who switch completely away from cigarettes.

The best choice any smoker can make is to quit tobacco and nicotine altogether. And while smoke-free products are not risk free and contain nicotine, which is addictive, scientifically substantiated smoke-free alternatives, like the THS, can play a significant role in tobacco harm reduction by providing acceptable alternatives to adult smokers who would otherwise continue to smoke.