Evidence doesn't support Philip Morris International's claims that its heat-not-burn tobacco product cuts the risk of tobacco-related diseases and is likely to switch adult cigarette smokers, regulatory advisors said.

PMI is seeking approval from the U.S. Food and Drug Administration to market its heat-not-burn tobacco product as less risky than cigarettes. PMI says it has found exclusively using iQOS significantly lowers users' risk of harm than if they were to continue smoking cigarettes.

The committee disagreed.

Members voted unanimously (aside from one abstention) against PMI's claim that its heat-not-burn tobacco product cuts the risk of tobacco-related diseases. The panel also rejected a claim that iQOS is less risky than continuing to smoke cigarettes in a 5-4 vote.

One claim the committee voted in favor of was that iQOS reduces the body's exposure to harmful or potentially harmful chemicals. However, it voted against the idea that reductions in exposure are reasonably likely to translate to a measurable and substantial reduction in morbidity and or mortality.

PMI told the committee it expects to switch 6 million adult smokers to iQOS if the FDA allowed it to market the system as less risky than cigarettes. Members were skeptical.

The majority said the likelihood of iQOS users switching completely to the device is low to medium.

One member pointed to price as a barrier. If approved, the heating device would cost $79 and the price of accompanying tobacco sticks would be comparable to a pack of cigarettes.

PMI has said using the iQOS system exclusively offers the greatest reduction in harm. The committee was not convinced that people would use iQOS alone. The bulk said the odds of people using it in conjunction with cigarettes are high to medium.

In response to the committee vote, the company released a statement:

Philip Morris International appreciates the open, positive dialogue and the serious consideration the Tobacco Products Scientific Advisory Committee (TPSAC) has shown during the last two days in discussing the complex science presented in our Modified-Risk Tobacco Product (MRTP) application. We are encouraged by the recognition of the risk reduction potential of IQOS that clearly emerged from the statements of the Committee members. We are confident in our ability to address the valid questions raised by the Committee with the FDA as the review process for our application continues.

One concern with alternative nicotine products like e-cigarettes is that they attract people who have never smoked, including kids and teens. PMI has said that's unlikely because iQOS uses actual tobacco, unlike e-cigarettes, which are available in fruity, sweet flavors. The committee's thoughts on the matter were mixed.

The recommendations are non-binding, meaning the FDA does not have to follow them.

Analysts Michael Lavery of Piper Jaffray and Bonnie Herzog of Wells Fargo remained optimistic the FDA would approve PMI's modified-risk tobacco product application. In separate research notes, they both noted committee members were concerned about the precise wording of PMI's proposed reduced-risk claims when voting against them.

PMI has another application under FDA review that would simply allow iQOS to be sold in the U.S., without the lower-risk claims. Regardless of the panel's views on the modified-risk tobacco product application, the process could help PMI's other application, said Marc Scheineson, a partner at Alston & Bird and a former associate commissioner for legislative affairs of the FDA.

Philip Morris shares closed down 2.8 percent on Thursday. Shares of Altria, which would receive sole distribution for iQOS in the U.S., if approved, fell 2.3 percent.