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.

About Sienna Biopharmaceuticals

Sienna Biopharmaceuticals is a clinical stage company focused on the discovery, clinical development and commercialization of innovative medical dermatology and aesthetics products based on scientific breakthroughs. Sienna Biopharmaceuticals' management comprises executives with extensive experience and demonstrated success in taking new scientific ideas from discovery to commercialization, including many of the most successful global brands in medical dermatology and aesthetics. Find more information at www.siennabio.com.

About ARCH Venture Partners

ARCH Venture Partners, one of the largest early stage technology venture firms in the U.S., invests in seed and early stage advanced technology companies. ARCH enjoys special recognition as a leader in the commercialization of technologies developed at academic institutions, corporate research labs and national laboratories. ARCH has earned a reputation as one of the leading venture firms in early stage biotechnology, advanced materials, alternative energy, and specialty semiconductors, and is known for identifying and capitalizing early on fundamental trends in disruptive technology. Now in its 30th year, ARCH has over $2 billion in committed capital through eight venture funds, and has co-founded and provided initial investments for over 200 companies.