The likelihood of Sanofi-Aventis finally getting the thumbs-up for its experimental heart drug Multaq looks bright this morning after US regulatory staff declared that the compound should be approved.

Ahead of a US Food and Drug Administration's Cardiovascular and Renal Advisory Committee meeting tomorrow (March 18), agency staff have posted documents on Multaq (dronedarone). A memo on the FDA’s website states that the compound "should be approved for the delay and recurrence of symptomatic events and decrease hospitalisation for atrial fibrillation”.

However the staffers also say that the mortality claim Sanofi is seeking should not be granted. “The prevention of death from any cause was not established,” said Gail Moreschi and Valeria Freidlin, who conducted the clinical and statistical review of the drug. “Therefore, a claim for preventing death from any cause cannot be included in the labelling.”

The memo also suggests that Multaq should not be used by patients suffering from severe heart failure (class III and IV). The staffers did note however, that “the tricky issue is how to control those whose heart failure transitions into class III from less severe degrees of heart failure”.

The reservations expressed in the memo, especially about the mortality claim, were “only a small negative”, claims Morgan Stanley analyst Andrew Baum in an investor note. He added that "we see Multaq as emerging into the first-line gold-standard therapy for the vast majority” of the seven million treatment-naive patients with atrial fibrillation.

Tim Anderson at Sanford Bernstein thinks a positive recommendation from the agency is likely. He noted that Multaq has “some genuinely controversial elements to it in terms of its risk/benefit profile, but when weighed against the profiles of existing therapies, we continue to believe the drug is more likely than not" to get the advisory committee’s support. However he also noted other comments of Moreschi and Friedlin who wrote that “the safety of dronedarone presents a problem that the label alone may not be able to cover”.

Still Sanofi is confident the data it has provided, notably from the Athena trial, which it says showed that Multaq reduced cardiovascular-related hospitalisations or deaths. The drug "represents a new advance in the management of patients with atrial fibrillation/flutter, addressing an important unmet clinical need," the company said.

All will be revealed in the next day or two. Multaq’s journey has been fairly tortuous ever since 2003, when Sanofi ended a Phase III trial (Andromeda) after an independent Data Safety and Monitoring Board saw a potential excess risk of death in patients. In 2006, the FDA rejected dronedarone and asked for more data.

Investors seem to think the company has done enough to get approval for a drug that could bring in $2 billion per year. Sanofi shares rose 4.1% to 41.80 euros after the memo was published.