8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): July 30, 2018

SIENNA BIOPHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

Delaware	001-38155	27-3364627
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification Number)

30699 Russell Ranch Road, Suite 140

Westlake Village, CA 91362

(Address of principal executive offices, including Zip Code)

Registrant’s telephone number, including area code: (818) 629-2256

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company   ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.   ☒

Item 8.01 Other Events

On July 30, 2018, Sienna Biopharmaceuticals, Inc. (the “Company”) announced top-line data from two pivotal trials with SNA-001 for the treatment of acne. Additionally, the Company will be hosting a conference call for analysts and investors to discuss the top-line results utilizing the attached presentation (the “Presentation”). A copy of the press release and the Presentation are filed as Exhibits 99.1 and 99.2 to this Current Report on Form 8-K, respectively, and incorporated by reference herein.

Item 9.01 Financial Statements and Exhibits

Exhibit No.	Description
99.1	Press Release dated July 30, 2018.
99.2	Presentation dated July 30, 2018.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	SIENNA BIOPHARMACEUTICALS, INC.
Date: July 30, 2018	By:	/s/ Timothy K. Andrews
		Timothy K. Andrews General Counsel and Secretary

EX-99.1

Exhibit 99.1

Sienna Biopharmaceuticals Announces Pivotal Trials with SNA-001 in Acne

Did Not Meet Primary and Secondary Endpoints

— Results from independent pivotal trials with SNA-001 for the reduction of unwanted light-pigmented

hair expected beginning in the fourth quarter of 2018

— Sienna continues to advance robust multi-asset pipeline, including SNA-120 and SNA-125

— Company will conduct conference call and webcast today at 8:15 a.m. ET

WESTLAKE VILLAGE, Calif., July 30, 2018 – Sienna Biopharmaceuticals, Inc. (NASDAQ:SNNA), a clinical-stage medical dermatology and aesthetics company, today announced that two pivotal acne trials with SNA-001 in conjunction with 1064 nm and 810 nm lasers did not show statistical significance on the primary and secondary endpoints. SNA-001 is a topical medical product derived from Sienna’s proprietary Topical Photoparticle Therapy™ platform.

“We are disappointed by these results, which did not confirm the findings from the previous proof of concept study. Acne is a complex, multi-factorial disease affecting most people at some point in their lives,” said Frederick C. Beddingfield III, MD, PhD, President and Chief Executive Officer of Sienna Biopharmaceuticals. “Researchers have long recognized the challenges to achieving clinically meaningful outcomes in acne. We conducted our trials with scientific rigor, but the data did not show a benefit from SNA-001. Sienna was founded on a strategy of developing a diversified multi-asset pipeline by a highly experienced team. We have several additional clinical studies from two separate technology platforms across a number of therapeutic indications and development stages reading out over the next three quarters, and remain highly focused on delivering innovative therapies that matter for patients.”

“As acne is a condition with inherent variability in the disease and the scales used to assess it, we deliberately constructed our trials with a powerful split-face design to address this,” said Paul F. Lizzul, MD, PhD, Chief Medical Officer of Sienna Biopharmaceuticals. “We executed the trials with the rigor expected in pharmaceutical studies, choosing high quality sites, applying good oversight and monitoring, and enrolling the right patients. However, the results showed that while SNA-001+Laser and Vehicle+Laser both showed an improvement in acne lesions from baseline, there was no additional benefit from SNA-001.”

These two, independent, multicenter, randomized, double-blind, split-face (within subject vehicle controlled) studies enrolled subjects 12 years and older with moderate to severe acne vulgaris. Subjects were treated three times over the course of two weeks on each side of the face with laser and either SNA-001 or Vehicle. The primary endpoint was evaluated three months after the last treatment, with no intervening therapies. Details of the two pivotal trials included:

SNA-001+810 nm laser (n=78)

• Primary endpoint: At 12 weeks following the last treatment, SNA-001+Laser and Vehicle+Laser demonstrated a 37.4 percent and a 36.5 percent reduction from baseline in inflammatory lesion count, respectively. The difference between treatments was not significant (p = 0.663).

• Secondary endpoints: Neither change from baseline in absolute inflammatory lesions nor Investigator Global Assessment (IGA) 1-grade responder rate were statistically significant.

SNA-001+1064 nm laser (n=89)

• Primary endpoint: At 12 weeks following the last treatment, SNA-001+Laser and Vehicle+Laser achieved a 38.7 percent and a 41.9 percent reduction from baseline in inflammatory lesion count, respectively. The difference between treatments was not significant (p = 0.411).

• Secondary endpoints: Neither change from baseline in absolute inflammatory lesions nor IGA 1-grade responder rate were statistically significant.

In both trials, SNA-001 was well-tolerated, with no clinically meaningful differences in adverse events (AEs) observed between SNA-001 and Vehicle treatment areas. AEs were mostly mild. The most frequently reported AEs were erythema, discoloration and edema.

Results from a third, independent pivotal trial in acne using SNA-001 in conjunction with a 755 nm laser are expected in the fourth quarter of 2018.

Sienna is separately investigating SNA-001 for the reduction of unwanted light-pigmented hair. The Company expects to report results from three pivotal trials with SNA-001 for the reduction of light-pigmented hair in the fourth quarter of 2018 and first quarter of 2019.

Sienna’s pipeline also includes two new chemical entities (NCEs) from the Company’s proprietary Topical by Design™ platform. Applications of this innovative technology are currently being explored with SNA-

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120 for use in pruritus associated with psoriasis, and SNA-125 for use in psoriasis and atopic dermatitis. Clinical data for these products are expected to be reported over the course of the next three quarters.

Conference Call and Webcast

Sienna will host a conference call today, July 30, at 8:15 a.m. Eastern Time to discuss the SNA-001 acne pivotal trials. Callers should dial in approximately 10 minutes prior to the start of the call. No reservation is necessary to participate on the call. The phone number to join the conference call is +1 (877) 376-9929 (toll-free in the United States and Canada) or +1 (629) 228-0733 (international). The conference identification number for the live call is 3265779.

The call will be webcast live and can be accessed through the Investor Relations section of the Company’s website at Investors.SiennaBio.com. An archived version of the webcast will be available approximately two hours following the live call for 90 days.

About Sienna Biopharmaceuticals

Sienna Biopharmaceuticals, Inc. is a clinical-stage biopharmaceutical company focused on bringing innovations in biotechnology to the discovery, development and commercialization of first-in-class, targeted, topical products in medical dermatology and aesthetics. The Company’s objective is to develop a unique, diversified, multi-asset pipeline of topical therapies that enhance the health, appearance and quality of life of dermatology and aesthetics patients. Sienna is led by a management team with extensive experience in product development and commercialization at several leading dermatology, aesthetics and biotechnology companies.

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 by Sienna’s Chief Executive Officer and Chief Medical Officer and other statements regarding Sienna’s expectations for the timing of additional data readouts for its clinical trials, including SNA-001 for the treatment of acne and the reduction of unwanted light-pigmented hair. Such forward-looking statements involve substantial risks and uncertainties that could cause Sienna’s clinical development programs, future

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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 the clinical development process, regulatory approval processes, the timing of regulatory filings, the challenges associated with manufacturing pharmaceutical drug and medical device products, Sienna’s ability to successfully protect and defend its intellectual property, 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 the Company 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:

Media

Caroline Van Hove

cvanhove@siennabio.com

818-575-6250

Crystal Muilenburg

cmuilenburg@siennabio.com

818-584-1035

Investors

Sean Andrews

sandrews@siennabio.com

818-629-2244

###

Sienna Biopharmaceuticals, Inc.

30699 Russell Ranch Road, Suite 140, Westlake Village, CA 91362

Office 818-629-2256 | Fax 818-706-1214

www.SiennaBio.com

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EX-99.2

SNA-001 Acne Pivotal Trials: Results with 1064 nm and 810 nm Lasers July 30, 2018 March 2017 Exhibit 99.2

Forward Looking Statements This presentation contains forward-looking statements. All statements other than descriptions of historical facts contained in this presentation, including statements regarding future operational and financial results and positions, business strategy, prospective products, potential market, commercial opportunity and market share, availability and potential sources of funding, clinical trial results, product approvals and regulatory pathways, research and development costs, timing (including but not limited to clinical development and regulatory timelines), strategies for completion and likelihood of success for our business activities, and plans for future operations, are forward-looking statements reflecting the current beliefs and expectations of management made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These statements involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you should not rely on these forward-looking statements as predictions of future events. The events and circumstances reflected in our forward-looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward-looking statements. Such risks and uncertainties include, among others, those inherent in the preclinical and clinical development process and the regulatory approval process; the risks and uncertainties in commercialization and gaining market acceptance; the risks associated with protecting and defending our patents or other proprietary rights; the risk that our proprietary rights may be insufficient to protect our product candidates; the risk that we will be unable to obtain necessary capital when needed on acceptable terms or at all; competition from other products or procedures; our reliance on third-parties to conduct our clinical and non-clinical trials; and our reliance on single-source third-party suppliers to manufacture clinical, non-clinical and any future commercial supplies of our product candidates. 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 our business in general, see our most recent Annual Report on Form 10-K filed with the Securities and Exchange Commission and our future current and periodic reports. Except as required by applicable law, we assume no obligation to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise.

Topical Photoparticle TherapyTM Platform (SNA-001)

Enrollment Primary Endpoint Secondary Endpoints Independent, multicenter, randomized, double-blind, split-face (within subject vehicle controlled) trials Three treatments over two weeks (7 + 1 days apart), each side of the face with laser and either SNA-001 or Vehicle Three separate clinical trials were initiated, using nearly identical protocols but different laser wavelengths corresponding to three commonly used commercial lasers, 755 nm, 810 nm and 1064 nm The Investor’s Global Assessment (IGA) severity scale consists of five severity grades: clear (0), almost clear (1), mild (2), moderate (3), severe (4) SNA-001 Acne Pivotal Trials with 1064 nm & 810 nm Lasers1 Trial Design Percentage change in inflammatory lesion count from baseline at 12 weeks post final treatment (conducted by the blinded investigator) Absolute change in inflammatory lesion count from baseline at 12 weeks post final treatment (conducted by the blinded investigator) IGA2 success at 12 weeks post final treatment (IGA success defined as a 1-point or greater decrease from baseline) Subjects 12 years and older with moderate or severe2 facial acne The 1064 nm trial enrolled across 9 sites a total of 89 subjects The 810 nm trial enrolled across 10 sites a total of 78 subjects

Primary Endpoint Data – 810 nm Laser Endpoint/Analysis Mean (SD1) Percentage Change from Baseline LS2 Mean in Treatment Difference p-value SNA-001 + Laser (N = 78) Vehicle + Laser (N = 78) Percentage change in inflammatory lesion count from baseline at 12 weeks post final treatment -37.4 (45.54) -36.5 (37.87) -1.981 0.663 SD = standard deviation LS = least squares

Primary Endpoint Data – 1064 nm Laser Endpoint/Analysis Mean (SD1) Percentage Change from Baseline LS2 Mean in Treatment Difference p-value SNA-001 + Laser (N = 89) Vehicle + Laser (N = 89) Percentage change in inflammatory lesion count from baseline at 12 weeks post final treatment -38.7 (47.89) -41.9 (44.78) 3.293 0.411 SD = standard deviation LS = least squares

Secondary Endpoint Data – 810 nm Laser Endpoint/Analysis  SNA-001 + Laser Vehicle + Laser LS1 Mean (SEM2) in Treatment Difference p-value Absolute change in inflammatory Lesion count from baseline at 12 weeks post final treatment Mean (SD3)     -7.3 (8.36) -7.1 (7.03) -0.483 (0.774) 0.534 IGA4 success5 at 12 weeks post final treatment n (%)     49 (62.8) 35 (44.9) N/A 0.003 LS = least squares SEM = standard error of the mean SD = standard deviation The Investor’s Global Assessment (IGA) severity scale consists of five severity grades: clear (0), almost clear (1), mild (2), moderate (3), severe (4) IGA success defined as a 1-point or greater decrease from baseline

Secondary Endpoint Data – 1064 nm Laser Endpoint/Analysis   SNA-001 + Laser Vehicle + Laser LS1 Mean (SEM2) in Treatment Difference p-value Absolute change in inflammatory Lesion count from baseline at 12 weeks post final treatment Mean (SD3)     -7.9 (9.67) -8.2 (9.56) 0.265 (0.724) 0.716 IGA4 success5 at 12 weeks post final treatment n (%)     53 (59.6) 48 (53.9) N/A 0.132 LS = least squares SEM = standard error of the mean SD = standard deviation The Investor’s Global Assessment (IGA) severity scale consists of five severity grades: clear (0), almost clear (1), mild (2), moderate (3), severe (4) IGA success defined as a 1-point or greater decrease from baseline

Safety Summary – 810 nm Laser Type of Event SNA-001 + Laser n (%) [Events] Vehicle + Laser n (%) [Events] Bilateral n (%) [Events] Treatment emergent adverse event (TEAE) 11 (14.1) [14] 5 (6.4) [8] 10 (12.8) [15] Serious adverse event (SAE) 0 (0) 0 (0) 0 (0) TEAE related to investigational device 5 (6.4) 2 (2.6) 3 (3.8) TEAE related to laser 9 (11.5) 5 (6.4) 5 (6.4) TEAE resulting in discontinuation from study 0 (0) 0 (0) 0 (0) TEAEs by Maximum Severity Mild 10 (12.8) 4 (5.1) 10 (12.8) Moderate 1 (1.3) 1 (1.3) 0 (0) Severe 0 (0) 0 (0) 0 (0) Most Frequently Reported TEAEs (>2%) by Preferred Term Application site erythema 7 (9) [7] 3(3.8)[3] 7(9) [8] Application site discolouration 2(2.6)[2] 2(2.6) [3] 2 (2.6) [2] Application site oedema 2(2.6)[2] 1(1.3) [1] 3(3.8)[3]

Safety Summary – 1064 nm Laser Type of Event SNA-001 + Laser n (%) [Events] Vehicle + Laser n (%) [Events] Bilateral n (%) [Events] Treatment emergent adverse event (TEAE) 0 (0) [0] 1 (1.1) [1] 17 (19.1) [33] Serious adverse event (SAE) 0 (0) 0 (0) 0 (0) TEAE related to investigational device 0 (0) 0 (0) 0 (0) TEAE related to laser 0 (0) 1 (1.1) 11 (12.4) TEAE resulting in discontinuation from study 0 (0) 0 (0) 0 (0) TEAEs by Maximum Severity Mild 0 (0) 1 (1.1) 13 (14.6) Moderate 0 (0) 0 (0) 4 (4.5) Severe 0 (0) 0 (0) 0 (0) Most Frequently Reported TEAEs (>2%) by Preferred Term Application site erythema 0 (0) [0] 0 (0) [0] 17 (19.1) [18] Application site discolouration 0 (0) [0] 0 (0) [0] 10 (11.2) [10] Application site oedema 0 (0) [0] 0 (0) [0] 3 (3.4)[3] Application site scar 0 (0) [0] 0 (0) [0] 2 (2.2) [2]

Regulated as a drug pursuant to a new drug application (NDA) regulatory pathway Regulated as a Class II medical device under 510(k) marketing clearance pathway TrkA = tropomyosin receptor kinase A JAK3 = Janus kinase 3 Technology Platform Research Pre-clinical Phase 1 Phase 2 Phase 3 Anticipated Milestones Topical by Design™ Top-line data in 1Q19 Data in 4Q18 Data in 3Q18 Technology Platform Research Pre-clinical Proof-of-Concept Pivotal Anticipated Milestones Topical Photoparticle Therapy™ Top-line data in 4Q18 Top-line data in 4Q18 Top-line data in 1Q19 SNA-1201: TrkA3 inhibitor (pruritus and psoriasis) SNA-1251: JAK3/TrkA inhibitor (psoriasis and pruritus) SNA-0012 (acne vulgaris – 755 nm) SNA-0012 (unwanted light-pigmented hair reduction – 1064 nm) SNA-1251: JAK34/TrkA inhibitor (atopic dermatitis and pruritus) SNA-0012 (unwanted light-pigmented hair reduction – 810 nm and 755 nm) Diversified Topical Pipeline