Obesity Drug Lorcaserin Rejected By FDA

Shelley Wood

October 25, 2010

October 25, 2010 (Silver Spring, Marylan) — Lorcaserin (Arena Pharmaceuticals), one of three antiobesity drugs the FDA is pondering in 2010 for potential market approval, has been turned down by the agency [1]. In a letter sent to the company, the FDA has asked for additional information on the drug's efficacy and safety.

Last month, the FDA's Endocrinologic and Metabolic Drugs Advisory Committee, voted 9 to 5 against approval.

In its letter, the FDA asked for additional details from a preclinical study, in rats, showing an increase in breast tumors, and expert insight into how the finding in rats might relate to lorcaserin's action in humans.

The FDA also noted that the weight-loss efficacy in nondiabetic overweight and obese subjects was "marginal" and asked that the company submit final results from the recently completed BLOOM-DM study. According to the company, "top-line" results from this study should be available within the next few weeks.

Both the cancer signal and the underwhelming efficacy of the drug were the two issues that preoccupied the advisory group during its daylong meeting in September. In the two phase III trials reported so far, BLOOM and BLOSSOM, average weight loss in lorcaserin-treated patients was 5 to 6 kg.

Mounting anticipation over the FDA's decision late Friday took an unusual turn after it emerged that the agency had sent a letter to certain Arena shareholders saying that it "regrets that no toxicologist participated" in its advisory committee meeting to shed some light on the cancer findings with the drug. As reported by Forbes, the letter was sent to a group of Arena investors who had complained to the agency that the advisory committee that had reviewed the lorcaserin data did not have the necessary expertise to make sense of the animal cancer data.

The negative decision by the FDA is a blow to those who say a new drug for obesity is desperately needed--only one prescription drug remains on the market for long-term treatment of obesity in the wake of sibutramine's withdrawal--and that patients are willing to accept some risk if it can help them lose weight.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.