SNNA Sienna Biopharmaceuticals Inc

Sienna Biopharmaceuticals, Inc. (Nasdaq:SNNA), a clinical-stage biopharmaceutical company, today announced that Paul F. Lizzul, M.D., Ph.D., Chief Medical Officer, and Silvio Traversa, B.Sc., Ph.D., Chief Scientific Officer, are scheduled to present at the Dermatology Drug Development Summit Europe, May 21-23, 2019, in Frankfurt, Germany. Dr. Lizzul also serves as the Summit’s Chair.

About the Presentations

Title: “Bridging the Innovation Gap in the Treatment of Mild to Moderate Dermatological Diseases”Presenter: Dr. LizzulDate and Time: Wednesday, May 22, 2019, 3:35 p.m. CETSynopsis:• Addressing the unmet need in topical drug development towards a large patient population with mild to moderate dermatological diseases, still primarily using topical steroids• Updating on SNA-120 (TrkA inhibitor) – SNA-120, a novel approach to the treatment of psoriasis, targeting NGF/TrkA and neurogenic inflammation– The important role of nerves & neuropeptides in psoriasis– Itch as a proxy clinical biomarker for high NGF/TrkA expression in psoriasis– A novel non-steroidal approach in the treatment of psoriasis and associated itch targeting the NGF/TrkA pathway

Title: “The Topical-by-Design Technology – Defying Conventional Wisdom”Presenter: Dr. TraversaDate and Time: Thursday, May 23, 2019, 9:30 a.m. CETSynopsis:• Does size really matter?• Exploring an innovative way of using polymers• Bringing potent drugs to derm fruition, minimizing systemic exposure

Dr. Traversa will also participate in the opening keynote panel discussion, “What’s Next in Dermatology Drug Development?”, Wednesday, May 22, 2019, 9 a.m. CET.

About SNA-120

SNA-120 (pegcantratinib) is Sienna’s Phase 3 topical, non-steroidal Tropomyosin receptor kinase A (TrkA) inhibitor under investigation for the treatment of psoriasis. TrkA is the high-affinity receptor for nerve growth factor (NGF). SNA-120 selectively targets the NGF-TrkA signaling pathway, which plays an important role in the pathogenesis of psoriasis and pruritus (itch). SNA-120 was developed using Sienna’s innovative proprietary technology platform (see About Topical by Design™ below).

SNA-120 (0.05%) demonstrated in a Phase 2b clinical trial statistically significant improvement compared to vehicle on important pre-specified endpoints of psoriasis disease severity, including the Investigator’s Global Assessment (IGA) 2-grade composite, comprising a 2-grade improvement from baseline and clear (0) or almost clear (1) skin, which has been the Phase 3 primary endpoint for topical psoriasis drugs approved by the U.S. Food and Drug Administration (FDA). Specifically, 29% of patients achieved success on the IGA 2-grade composite, compared to 13% of subjects treated with vehicle. Similarly, 27% of subjects also experienced a 75% reduction from baseline in their Psoriasis Area and Severity Index score (PASI 75), compared to 13% of subjects treated with vehicle. Subjects also experienced an approximately 60% reduction from baseline in the associated pruritus, although the pruritus result did not reach statistical significance compared to vehicle. SNA-120 was well tolerated with no serious treatment-related adverse events. Treatment-related adverse events were observed in two patients and included dermatitis (0.5% group) and pain and pruritus (vehicle group). SNA-120 has been administered to more than 500 subjects for up to 12 weeks and has been well tolerated across all trials, with minimal to no demonstrated systemic bioavailability.

As part of the Phase 2 trial, biopsy analyses were conducted at The Rockefeller University on 22 subjects, and included Immunohistochemistry (IHC), MicroArray and quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR). These data showed SNA-120 affects key inflammatory cytokines involved in psoriasis, including IL-23, IL-12, IL-17A and IFNg, among others, and continue to support the mechanism of action of SNA-120 and the unique contribution of neurogenic inflammation to psoriasis pathogenesis.

Following a positive End-of-Phase 2 (EOP2) meeting with the FDA in April 2019, Sienna is progressing towards enrollment of the first patient in its Phase 3 program with SNA-120 for psoriasis in the second half of 2019.

About Topical by Design™

Topical by Design™ is Sienna’s innovative proprietary technology platform, which applies a scientific design process to create potent targeted pharmacologically active molecules that are directed toward a specific target tissue and a select disease pathway, and with minimal to no systemic exposure. By stably linking a short polyethylene glycol (PEG) polymer to a pharmacologically active molecule, Sienna’s technology platform alters the mechanism of action of the starting pharmaceutical ingredient and refines its target selectivity, enabling highly localized drug concentration in various target tissues, while dramatically minimizing systemic exposure. This approach of providing efficacy without compromising safety has unlocked a pipeline of selective tissue–targeted kinase inhibitors (TTKI) that target select pathways in specific tissues to treat a variety of chronic inflammatory and immunologic conditions.

About Sienna Biopharmaceuticals

Sienna Biopharmaceuticals, Inc. is a clinical-stage biopharmaceutical company focused on bringing unconventional scientific innovations to patients whose lives remain burdened by their disease. We draw upon our deep knowledge and experience in drug development across multiple therapeutic areas as we build a unique, diversified, multi-asset portfolio of therapies in immunology and inflammation that target select pathways in specific tissues, with our initial focus on one of the most important ‘immune’ tissues, the skin. We are leading the way with our novel proprietary technology platform, applying a scientific design process to create potent targeted pharmacologically active molecules that are directed toward a specific target tissue and a select disease pathway, and with minimal to no systemic exposure. At Sienna, we are going where it still matters for patients.

For more information, visit the Company’s website at www.SiennaBio.com.

Forward-Looking Statements

This press release contains forward-looking statements, including but not limited to statements regarding Sienna’s SNA-120 Phase 2b data and the progress and timing of Sienna’s SNA-120 development, including anticipated enrollment in the Phase 3 program for SNA-120. Such forward-looking statements involve substantial risks and uncertainties that could cause Sienna’s clinical development programs, future results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, the uncertainties inherent in the pharmaceutical drug and medical device development processes, including regulatory approval processes, the timing of regulatory filings, the challenges associated with manufacturing pharmaceutical drug and medical device products, Sienna’s ability to raise sufficient capital to fund its development programs, and other matters that could affect the sufficiency of existing cash to fund operations and the availability or commercial potential of Sienna’s drug candidates. Sienna undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the business of Sienna in general, see Sienna’s most recent Annual Report on Form 10-K and any subsequent current and periodic reports filed with the Securities and Exchange Commission.

Contact:

MediaCaroline Van Hovecvanhove@siennabio.com818-575-6250

InvestorsSean Andrewssandrews@siennabio.com818-629-2244