Drug Company Defends Diet Drug Despite Tumors in Lab Rats

From Reuters.com

By Lisa Richwine

ADELPHI, Maryland (Reuters) – Arena Pharmaceuticals Inc urged U.S. advisers on Thursday to back its proposed prescription weight-loss pill, arguing the medicine was safe for people despite tumors in lab rats.

Winning the panel’s support would move the drug, lorcaserin, closer to the U.S. market. The medicine is crucial to the small San Diego-based drugmaker, which was founded in 1997 and has no approved products.

Arena began its pitch by directly challenging concerns about cancerous tumors seen in rats. The company said the findings did not apply to people because the rat tumors resulted from high doses or biological mechanisms specific only to rodents.

“Lorcaserin does not pose a cancer risk to humans at the recommended therapeutic doses,” Dr. Gary Williams, a public health professor at New York Medical College who spoke for Arena, told the panel.

He also pointed to nine medicines that were approved with evidence of the same types of rat tumors seen with lorcaserin.

Food and Drug Administration reviewers highlighted the cancer issue as a key concern in an initial analysis released

on Tuesday. Investors fled the stock, sending the company’s shares down 45 percent since Monday’s close.

Industry analysts said ahead of the meeting Arena could have a tough time reassuring the panel the drug would not raise cancer risk in people.

“We suspect that the vote will likely be a close one going against approval of lorcaserin prior to additional trials to rule out the risk of cancer,” BMO Capital Markets analyst Jason Zhang said in a research note.

Consensus forecast data from Thomson Reuters shows analysts expect Arena’s drug could reach peak annual sales of $822 million if it reaches the market. Japan‘s Eisai Co holds U.S. marketing rights to lorcaserin.

Drugmakers have failed for decades to produce a pill to help people shed a significant number of pounds without serious side effects. Risks of current options were highlighted on Wednesday when U.S. advisers agreed tougher action was needed on Abbott Laboratories Inc’s diet drug Meridia but split on whether the drug should be banned.

Two other companies, Vivus Inc and Orexigen Therapeutics Inc, have weight-loss pills under FDA review this year. All three companies are trying to launch the first new prescription diet drug in a decade.

While the current U.S. obesity drug market is small — prescription and over-the-counter diet pills took in $381.5 million in 2009, according to data from IMS Health — some analysts have said a new product could more than double that.


Arena’s lorcaserin was designed to block appetite signals in the brain in a similar way to the now-withdrawn fenfluramine in the fen-phen diet drug cocktail. The Arena drug is more selective in the receptors it affects, and the company says studies have not found any of the heart-valve problems with lorcaserin that were linked to fenfluramine.

FDA reviewers, in 270 pages of analysis prepared for Thursday’s advisory panel, said they would ask the outside experts to consider data on heart-valve disease, psychiatric and memory problems and cancerous tumors in rats.

They also said one of the doses Arena tested met agency criteria for effectiveness “by a slim margin.” In company studies, patients who took 10 milligrams of lorcaserin twice daily for a year lost about 5.8 percent of their body weight on average. Placebo patients lost 2.5 percent.

The advisory panel is expected to vote Thursday afternoon on whether to recommend approval of lorcaserin. The FDA usually follows panel advice and is due to make a final decision by October 22. The drug’s proposed brand name is Lorqess.

Arena is developing other drugs for treatment of blood clots, sleep disorders and pulmonary arterial hypertension, but all are in early testing.

(Reporting by Lisa Richwine; Editing by Tim Dobbyn, Dave Zimmerman)

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