The likelihood of a new obesity drug getting on the market in the USA soon has risen after advisors to the US Food and Drug Administration backed Arena Pharmaceuticals and Eisai's lorcaserin.

The agency's Endocrinologic and Metabolic Drugs Advisory Committee voted 18 to 4, with one abstention, that the available data demonstrate that the potential benefits of lorcaserin outweigh the potential risks when used long-term. The Prescription Drug User Fee Act date for the FDA's final decision is June 27.

The positive vote is a major coup for Arena, given that the drug was rejected by the FDA in 2010 when the agency claimed the treatment showed modest weight loss. It was also concerned about tumours found in animal studies.

At the end of 2011, Arena refiled the drug, which acts as a selective serotonin 2C receptor agonist, but earlier this week, FDA staffers reiterated the aforementioned concerns. However, they also noted that new data seemed to rule out an excess risk of valvular heart disease, though some panellists disagreed.

One of them, Sanjay Kaul of the Cedars Sinai Medical Center who voted against, said "the weight loss did not translate into a tangible benefit in clinically relevant cardiometabolic biomarkers, quality of life, or risk prediction models", except for improvement in HbA1c in the cohort with type 2 diabetes ". He added that "there remains lingering uncertainty regarding potential valvulopathy associated with lorcaserin".

Arena chief executive Jack Lief claimed that the advisory committee's positive vote "supports our belief in lorcaserin as a potential new treatment option for the medical management of overweight and obesity". Once the news about the FDA panel thumbs-up came through, Arena and Eisai expanded their marketing and supply agreement for the drug to cover Canada, Mexico and Brazil, as well as the USA.

Support for lorcaserin comes a month after the FDA extended the PDUFA goal date from April 17 to July 17 for the New Drug Application on Vivus' rival obesity drug Qnexa (phentermine/topiramate), which was backed 20-2 by the agency's panel in February. Another weight loss drug, Orexigen Therapeutics/Takeda's Contrave (naltrexone/bupropion) is currently in a cardiovascular outcomes trial having also been turned down by the FDA earlier.