[April 08, 2009]

BioWorld Today April 9, 2009

(BioWorld Today Via Acquire Media NewsEdge) With limited cash and a pipeline narrowed to a single drug - Silenor (doxepin), an H1 histamine blocker for insomnia - San Diego-based Somaxon Pharmaceuticals Inc. is crossing its fingers that a reanalysis of clinical data will provide sufficient answers to the FDA's February complete response and finally get the drug to market.

The complete response letter had raised issues with the interpretation of efficacy data, and the agency said the new drug application could not be approved in its original form, though it did not come out and request additional trials.

Following a meeting with the FDA's Division of Neurology Products earlier this week, Somaxon said it plans to conduct additional analyses, looking specifically at the durability of subjective sleep maintenance efficacy in adults with primary insomnia.

The company will be relying on existing data, Meg McGilley, Somaxon's chief financial officer, told BioWorld Today.

"We'll be looking for some new perspective on the data that will satisfy" the agency's requests, McGilley noted.

She said the firm has not yet disclosed a time frame for the reanalysis. But, if Somaxon successfully compiles the needed efficacy data, "we'll resubmit [the NDA] and that starts a six-month review at the FDA." When asked what Somaxon plans to do if the data are not sufficient, McGilley responded that the firm would "have to evaluate other options." The reaction from Wall Street was not encouraging, as shares (NASDAQ:SOMX) fell 36.5 percent, or 23 cents, to close Wednesday at 40 cents.

In fact, Somaxon's stock has not recovered since the company received the complete response letter for Silenor, when it nose-dived from $2.14 to 39 cents, a long way down from the $11-per-share pricing when the company first went public in late 2005.

But back then, the firm had insomnia drug Silenor in Phase III studies and was working on an oral nalmefene formulation in-licensed from BioTie Therapies Corp. for impulse control disorders. A third candidate, a reformulated version of alcohol dependence drug acamprosate calcium, was in development for movement disorders. (See BioWorld Today, Dec. 16, 2005.) In 2007, Somaxon dropped development of acamprosate calcium after early stage trials failed to show whether the drug worked in patients at lesser dose levels. And work halted on nalmefene, after that drug missed its endpoint in a Phase II/III study in patients diagnosed with pathological gambling.

Earlier this year, Somaxon and Turku, Finland-based BioTie terminated their agreement on nalmefene - the North American and Mexican rights later were picked up by BioTie's overseas partner H. Lundbeck A/S - though the end of that deal did come with a $1 million termination fee to Somaxon, McGilley said.

That adds to the firm's cash position of $14.3 million as of Dec. 31, 2008. "We're aggressively managing our spending," she said, adding that Somaxon recently implemented cost-cutting measures and some work force reductions. Currently, the company has 13 employees.

Going forward, its work will focus solely on the reanalysis of Silenor data. According to the FDA's response letter, objective and subjective efficacy must clearly be established in adult and elderly patients for drug approval, and that efficacy must be shown both at the beginning of treatment and on a persistent basis, defined as at least one month.

Silenor, a low-dose tablet of doxepin hydrochloride that blocks the H1 histamine receptor - believed to play a role in the sleep-wake cycle - demonstrated in pivotal trials an ability to improve sleep onset and sleep maintenance, and helped prevent early awakening, with few side effects.

Somaxon had intended to seek labeling for the drug for improving both sleep onset and sleep maintenance, but after meeting with the agency decided not to pursue a sleep onset indication.

"A larger proportion of [insomnia] patients have sleep maintenance issues," McGilley said. Most of the insomnia drugs available, such as Ambien (zolpidem, Sanofi-Aventis Group) and Lunesta (eszopiclone, Sepracor Inc.), are mostly for sleep onset, she added, but are less effective for patients who need sleep maintenance therapy.

"So there's a viable opportunity here," she said.

In the meantime, Somaxon continues looking for a partner that can get Silenor out to the primary care market. "Discussions have been ongoing for some time," McGilley said.

The company also is working on a two-year carcinogenicity study in rats, the results of which would be submitted as part of its post-approval commitment for Silenor. That trial started in August 2007, and data are expected in the first quarter of 2010. n (c) 2009 Thomson BioWorld, All Rights Reserved.

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