KYTHERA Biopharmaceuticals Presents Positive Data From Two Phase 2 Studies With ATX-101.

-Study Results Demonstrated Statistically Significant Reduction in Patients' Unwanted Submental Fat-

LOS ANGELES -- KYTHERA Biopharmaceuticals, Inc. (KYTHERA) today presented detailed results from two double-blind Phase 2 studies, each designed to evaluate the safety and effectiveness of ATX-101, a first-in-class injectable drug for the reduction of small volumes of fat. Top-line results from these studies, which examined use of ATX-101 for reduction of unwanted localized fat deposits under the chin (submental fat), were announced in January 2009 (http://www.kytherabiopharma.com/press_releases.html).

Kevin C. Smith MD, FAAD, FRCPC presented study results in Scientific Session at the American Society for Dermatologic Surgery (ASDS) and American Society of Cosmetic Dermatology and Aesthetic Surgery (ASCDAS) Joint Annual Meeting. A recap of the data presentation will be available online at http://www.kytherabiopharma.com/investors.html for seven days.

"ATX-101 shows promise for patients who are seeking a minimally invasive treatment for unwanted localized submental fat," said Kevin C. Smith, a Canadian investigator in both Phase 2 studies. "The significant reduction we saw in submental fat for patients treated with ATX-101 illustrates its potential as a safe, simple prescription aesthetic product."

In total, one hundred fifty-seven subjects were randomized in two double-blind, placebo-controlled, dose-ranging studies conducted across 10 centers in the United Kingdom, Canada and Australia. Across these studies, subjects received one of five dosing regimens of ATX-101 or placebo; one dosing regimen was duplicated between studies.

In each study analyzed independently, two of the three dosing regimens tested yielded a statistically significant reduction of unwanted submental fat compared to placebo as measured by physician assessment (ATX-101-06-03 both p<0.05, and ATX-101-07-07 both p<0.01). Submental fat was evaluated at baseline and week 16, using a 5-point Submental Fat Rating Scale.

Similarly, subject self-assessment indicates that treatment with ATX-101 yielded statistically significant improvement in three of three (ATX-101-06-03, all p<0.05) and two of three (ATX-101-07-07, both p<0.01) dosing regimens versus placebo. Subjects were asked to rate appearance at baseline and week 16, using a 7-point Subject Satisfaction Rating Scale.

As presented at the ASDS Meeting, the five active dosing regimens tested were collapsed into three overall dose groups (1, 2 and 4 mg/cm2). Treatment with ATX-101 resulted in statistically significant results on both physician and subject assessments versus placebo (baseline to week 16) in all dose groups (p<0.05).

"We're very pleased with the outcome of these robust trials. The safety profile and the statistically significant efficacy in patients receiving ATX-101 strongly support expansion of our product development efforts," said Patricia Walker, MD, PhD, KYTHERA's Chief Medical Officer.

In both studies, ATX-101 was well tolerated. The most common adverse events were mild pain, swelling, numbing at the injection site, bruising, and induration. These adverse events were limited to the injection site, and most were temporally associated with treatment and resolved within the treatment interval of 28 days. No systemic adverse events were reported.

In long-term follow-up (63 weeks post baseline), the reduction in submental fat for ATX-101-treated patients was sustained.

Full results from these studies will be published in an appropriate peer reviewed journal.

About ATX-101

ATX-101 is a first-in-class injectable drug being studied for the reduction of small volumes of fat. It is based on an endogenous compound with unique features including selectivity for adipocytes and rapid clearance. ATX-101 clinical research is focused on reducing localized fat deposits, including submental fat. KYTHERA has completed two randomized, double-blind, placebo-controlled, Phase 2 studies with ATX-101 in the reduction of submental fat and two Phase 1 studies: pharmacokinetic and histology.

About Submental Fat (SMF)

Submental fat is a localized subcutaneous fat deposit located immediately beneath the chin and jawline. In the rapidly growing market of minimally-invasive, non-surgical facial rejuvenation, the reduction of facial fat deposits to restore and reshape the jawline remains one of the largest unmet patient needs. According to a recent national, multi-center, clinical evaluation of more than 220 BOTOX([R]) and dermal filler patients, 79% of patients had a measurable excess of submental fat. Currently, there are no FDA approved drugs to reduce excess localized fat.

About KYTHERA Biopharmaceuticals

KYTHERA is a privately held biopharmaceutical company that applies the tools of biotechnology to develop innovative prescription therapeutics for aesthetic medicine. KYTHERA has active programs in adipolysis (ATX-101), facial contouring (ATX-104) and pigmentation modulation (ATX-202).

For more information about KYTHERA, please visit the company's Web site at www.kytherabiopharma.com.

BOTOX([R])is a registered trademark of Allergan, Inc.