Those who argued there was a 'fat chance' the FDA would approve the Arena diet pill were correct. The drugmaker issued a statement this morning saying the agency sent a complete response letter and the rejection can be attributed to waiting for results of a trial in patients with diabetes, concerns the Lorqess pill may cause tumors in rats and that efficacy was marginal.
The outcome is hardly surprising, given the issues raised by FDA reviewers at an advisory committee meeting (look here). The session may have prompted outrage among some investors, who generated considerable attention by circulating a petition insisting FDA staff was biased, but the agency is exercising considerable caution these days over safety issues (back story). This is especially true for diet pills after more than a decade of safety surprises, even though obesity remains a huge problem.
"With respect to the clinical reasons, the FDA stated in the CRL that the weight loss efficacy of lorcaserin in overweight and obese individuals without type 2 diabetes is marginal...," the Arena statement says. "The FDA also stated in the letter that in the event evidence cannot be provided to alleviate concern regarding clinical relevance of the tumor findings in rats, additional clinical studies may be required to obtain a more robust assessment of lorcaserin's benefit-risk profile." Lorcaserin is the chemical name for the drug, by the way.
The upshot: the Arena pill is unlikely to wind up on pharmacy shelves for a year or more. And if it does, the FDA is also recommending that it be placed on Schedule IV of the Controlled Substance Act, which includes drugs that may lead to limited physical dependence or psychological dependence. Investors may have smelled a rat, but they shouldn't have been surprised.