Auxilium Pharmaceuticals, a specialty biopharmaceutical company, said the first cohort of patients has been dosed in its phase Ib trial of Xiaflex (collagenase clostridium histolyticum) for the treatment of edematous fibrosclerotic panniculopathy (EFP), commonly known as cellulite.

Cellulite, a localized metabolic disorder of tissue under the skin, has been reported to occur in 85-98% of post-pubertal females.

The Xiaflex treatment is intended to target and break collagen tethers (which attach skin to lower layers of muscle, causing dimpling), with the goal of releasing skin dimpling and potentially resulting in the smoothing of skin.

The phase Ib study is a single-site, open-label, dose-escalation study targeted to enroll 63 women aged 21 to 60. The objectives of the study are to assess the safety, effectiveness and pharmacokinetics of Xiaflex for the treatment of EFP. Top line results are expected in the second half of 2012.

"Current treatments of cellulite with creams, light-based procedures or liposuction provide limited or no effectiveness,” said Dr. James Tursi, chief medical officer at Auxilium. “The clinical development of Xiaflex, if successful, could lead to the first FDA-approved, office-based medical treatment option that is supported by scientific results."

Study participants will be assigned to one of seven groups that vary in treatment dose, injection concentration and volume. Subjects will receive 10 concurrent injections (0.1mL or 0.5mL per injection) of Xiaflex via a standardized template over a targeted area (8 cm x 10 cm) of EFP.  The total dose will range between 0.0029mg and 0.116mg; these doses represent between 0.5% and 20% of the dose used in a single injection for Dupuytren's contracture (0.58mg).

To qualify for the study, participants must have EFP in the posterolateral thighs and/or buttocks for at least 12 months prior to a screening visit.