Sienna Biopharmaceuticals Announces Second Closing of Series A Financing

STRONG INVESTOR DEMAND INCREASES TOTAL INVESTMENTS TO $46M

Westlake Village, CA, July 12, 2016 – Sienna Biopharmaceuticals, Inc. (Sienna), a clinical stage company focused on medical dermatology and aesthetics, today announced it has completed a second closing of its Series A financing, securing an additional $12 million in equity capital and bringing the total capital raised to approximately $46 million. This tranche was led by existing investors ARCH Venture Partners and Partner Fund Management and includes new investor Two River. Additional investors in the initial Series A included Altitude Life Science Ventures and Venvest Capital, as well as direct investment by several prominent aesthetics and medical dermatology industry luminaries.

The additional investment proceeds are targeted to fund Sienna’s pharmaceutical research and advance its business development efforts. Sienna’s lead proprietary technology, Silver Plasmonic Therapy (SPT) has promising applications for acne and permanent hair removal. Clinical trials are already underway and the Company is evaluating additional potential indications.

Sienna Biopharmaceuticals’ mission is to bring to market innovative new products that have the potential to improve patient outcomes and advance the practice of medicine in medical dermatology and aesthetics. The Company brings together the proven leadership and executive team from Kythera Biopharmaceuticals, Inc. (“Kythera”), recently acquired by Allergan, and the backing of several investors who supported the growth and success of Kythera. Leading the Company is Frederick C. Beddingfield III, MD, PhD as President and CEO, and Keith Leonard, as Executive Chairman.

“Securing this additional financing from high-quality new and existing investors demonstrates confidence in the Sienna team and our medical dermatology and aesthetics programs,” said Frederick C. Beddingfield III, MD, PhD, President and CEO of Sienna Biopharmaceuticals. “With our proven team and the strength and experience of our supportive investors, this Series A financing will allow us to accelerate our development programs and hopefully bring these technologies closer to benefitting patients.”

Experienced Management Team Sienna Biopharmaceuticals’ executive team comprises experienced industry executives with demonstrated success in aesthetics and medical dermatology having helped develop or commercialize leading global brands such as KYBELLA®, BOTOX®, DYSPORT®, JUVEDERM®, VOLUMA®, RESTYLANE®, LATISSE®, SOLODYN®, and ACZONE®. Combined, the team has worked on over 75 aesthetic and medical dermatology products; been responsible for more than 100 international regulatory filings and approvals; participated in 6 U.S. FDA Advisory Committee meetings including a recent 17-0 unanimous vote for and subsequent approval of KYBELLA®; and helped achieve 17 U.S. FDA approvals plus more than 35 FDA device clearances. For a full review of the management team please see www.siennabio.com.

Silver Plasmonic Therapy (SPT) Technology The Company is developing novel approaches to treat skin based on the science of plasmonic resonance, originally developed at Sienna Labs, Inc. under the leadership of Todd Harris, PhD. SPT entails using a proprietary topical solution containing patented plasmonic particles which interact with the light emitted by existing medical laser systems allowing controlled targeting of microstructures in the skin. The Company believes the treatment has the potential to meet unmet needs in the areas of acne, hair removal, and potentially other indications.

Contact: John W. Smither Chief Financial Officer jsmither@siennabio.com

Investors and Media: Derek Cole 720.785.4497 derek.cole@IRadvisory.com

http://siennabio.com/2016/07/sienna-biopharmaceuticals-announces-second-closing-of-series-a-financing/