Auxilium Pharmaceuticals, Inc., a specialty biopharmaceutical company, and Xstelos Holdings, Inc. have filed a lawsuit against Upsher-Smith Laboratories, Inc. (USL) for infringement of ten US patents covering Testim, one per cent testosterone gel, that are listed in the Approved Drug Products with Therapeutic Equivalence Evaluations (commonly known as the Orange Book), published by the US Food and Drug Administration (FDA). These ten patents are owned by FCB I LLC, an indirect majority owned subsidiary of Xstelos, and are exclusively licensed to Auxilium.

Xstelos holds the assets of CPEX Pharmaceuticals, Inc., the predecessor owner of the patents. The lawsuit was filed in the United States District Court for the District of Delaware on January 28, 2013.

Auxilium and Xstelos filed this lawsuit in response to a notice letter sent by USL regarding its filing with the FDA of New Drug Application (NDA) No. 204399 for a one per cent testosterone gel product. This letter also stated that NDA No. 204399 contained Paragraph IV certifications, under 21 USC Section 314.52(c) of the Federal Food, Drug, and Cosmetic Act, with respect to the ten patents listed in the Orange Book as covering Testim: US Patent Nos. 7,320,968; 7,608,605; 7,608,606; 7,608,607; 7,608,608; 7,608,609; 7,608,610; 7,935,690; 8,063,029; and 8,178,518. These ten patents are expected to expire on various dates ranging from April 21, 2023 through January 18, 2025. Auxilium and Xstelos remain committed to protecting their intellectual property rights, including their patent protection for Testim.

Under the Hatch-Waxman Act, as a result of the patent infringement lawsuit filed against USL, final FDA approval of USL's NDA for its proposed generic version of Testim will be stayed until at least the earlier of 30 months from the date USL's notice letter was received (i.e., June 24, 2015) or final resolution of the pending patent infringement lawsuit. While USL may receive tentative approval from the FDA for its version of Testim before one of those events occurs, it would not be permitted to launch its generic product in the US until it receives the necessary final approval of its NDA from the FDA.

Auxilium is a specialty biopharmaceutical company with a focus on developing and marketing products to predominantly specialist audiences.

Xstelos is a holding company formed for the purpose of holding the assets of CPEX Pharmaceuticals, Inc., an indirect, majority owned subsidiary of Xstelos. FCB I LLC is a wholly owned subsidiary of CPEX Pharmaceuticals, Inc.