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SEC Filings

S-1/A
OREXIGEN THERAPEUTICS, INC. filed this Form S-1/A on 02/16/2007
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2005, Xenical accounted for approximately 679,000 prescriptions in the United States, or approximately $87 million in sales, according to IMS Health. Orlistat was recently launched over-the-counter in the United States by GlaxoSmithKline under the brand name Alli.
 
Despite the large market opportunity for anti-obesity agents, there are relatively few competitive products in late stage clinical development. Rimonabant, which has been developed by Sanofi-Aventis under the U.S. brand name Acomplia and in Europe as Zimulti, is the most advanced. It has been approved in certain countries outside of the United States and has received an approvable letter from the FDA relating to potential marketing in the United States. Rimonabant is the first in a new class of anti-obesity drugs that work as antagonists at the cannabinoid type 1, or CB-1, receptor. This is the same receptor that is stimulated by cannabis. While rimonabant has shown efficacy (average 4.7kg or 4.85%) across several large Phase III clinical trials at the highest dose tested, it has also been associated with significant CNS side effects, including depression and related symptoms, according to a 2006 report published in Drugs. The overall risk-to-benefit profile of rimonabant is yet to be defined.
 
A number of other biotechnology and pharmaceutical companies have drugs in development for obesity. These include Arena Pharmaceuticals, Inc., Amylin Pharmaceuticals, Inc., Alizyme plc, Merck & Co., Inc., Peptimmune, Inc. and Vivus, Inc., among others. With the exception of Vivus, Inc., most of these efforts are directed toward a monotherapeutic approach which we would expect to be subject to the same early plateau typically seen. Vivus, Inc. has shown strong efficacy with a combination approach of phentermine and topiramate in a single center study, according to that company’s May 2006 press release.
 
In addition, we may face competition from generic products. Each of bupropion, naltrexone and zonisamide is available in generic form. However, we have undertaken strategies which we believe may impede potential competition from generic products. Supplementing our existing composition patents and patent applications, we have developed formulations and dosages of Contrave and Excalia that we believe may improve patient outcomes and provide further barriers to entry for potential competitors. We believe there cannot be an AB-equivalence designation for the generic versions of the constituents comprising Contrave and Excalia because of differences in pharmacokinetics between the existing generically available formulations and doses and the formulations and doses we plan to use. For naltrexone and zonisamide, we have selected dosages and are using formulations that are not currently available in generic form and create a different pharmacokinetic profile from the generic forms of these drugs. For bupropion, we are utilizing dosages that are not currently generically available. As a result, pharmacists are legally prohibited from substituting generics to match the dosages of Contrave and Excalia. We believe that our existing in-licensed composition patents and, if issued, our pending composition patents, will prevent generic firms from manufacturing comparable formulations and from marketing the constituent compounds together. In addition, we believe that practitioners who are seeking to prescribe safe and effective therapy are not likely to prescribe off-label generics in place of Contrave or Excalia because the dosages, pharmacokinetic profile and titration regimens for our Contrave and Excalia product candidates would not be available using existing generic preparations. Moreover, while general practitioners are the primary prescribers of anti-obesity therapies and are generally familiar with bupropion, they are not the primary prescribers of the other constituents of our product candidates, naltrexone and zonisamide. Accordingly, we believe that general practitioners will be unlikely to prescribe generic compounds with which they are unfamiliar. As a result, we believe that we have established a position with both Contrave and Excalia that will limit generic competition.
 
Third-Party Reimbursement
 
Despite the recognition of obesity as a chronic disease and its enormous cost to our health care system, universal coverage of and reimbursement for drugs to treat obesity by both public and private payors is lacking. However, third-party reimbursement in obesity care appears to be evolving. Recent changes in government-sponsored programs, in addition to growing recognition by private commercial plans of the economic benefits of treating obesity, has led to increasing coverage of pharmaceutical treatments.


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