Female Libido Drug Maker Appeals Second FDA Rejection

Megan Brooks

December 12, 2013

Sprout Pharmaceuticals is appealing a complete response letter (CRL) it received from the US Food and Drug Administration (FDA) over the company's resubmitted new drug application (NDA) for flibanserin, the company said December 11.

Flibanserin is an investigational 5-hydroxytryptophan (HT)(1A) receptor agonist and 5-HT(2A) receptor antagonist for treatment for young women with hypoactive sexual desire disorder, the most commonly reported form of female sexual dysfunction.

In June 2010, the FDA's Advisory Committee for Reproductive Health Drugs voted 10 to 1 against recommending approval of flibanserin, as reported by Medscape Medical News.

The advisory panel felt the drug was not significantly better than placebo for hypoactive sexual desire disorder and that the benefits did not compensate for its adverse effects, which include depression and dizziness.

In June, the company resubmitted the NDA for flibanserin, which included 14 new clinical studies with data on more than 3000 new patients, expanding the number of participants having completed clinical trials to more than 11,000, including more than 5000 patients who were treated with flibanserin in phase 3 efficacy studies, the company said.

Earlier this year, the company received the second CRL in response to the resubmitted NDA, which they are appealing. The FDA issues a CRL when it determines it will not approve the application in its present form.

Sprout said it recently completed an end-of-review meeting in which the FDA "provided the Company with a more complete understanding of its review of the NDA."

"Sprout strongly believes that it has satisfied the statutory requirements for approval of flibanserin," Cindy Whitehead, president and chief operating officer of Sprout Pharmaceuticals, said in a statement.

"In clinical trials, flibanserin has outperformed placebo with statistical significance and, importantly, women treated with flibanserin perceived their improvement to be clinically meaningful," she noted.

What the FDA "characterizes as a modest effect in their risk/benefit evaluation, we see as meaningful effect on the hallmark characteristics of the condition," Whitehead added, and is "the basis of our dispute."

"Further, in the risk/benefit evaluation, we believe that the safety profile of flibanserin is similar to that of other approved drugs where effect was characterized as modest by the agency and can be managed through a combination of labeling and responsible product launch, including postmarket assessments and communications. If approved, flibanserin could meet an important unmet medical need for women," Whitehead said.

The FDA accepted Sprout's formal dispute resolution request on December 3. The company expects a response from the FDA on the appeal in the first quarter of 2014.


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