Organization and Nature of Business	12 Months Ended
Dec. 31, 2016
Organization and Nature of Business
Organization and Nature of Business	1. Organization and Nature of Business Aclaris Therapeutics, Inc. was incorporated under the laws of the State of Delaware in 2012. On July 17, 2015, Aclaris Therapeutics International Limited (“ATIL”) was established under the laws of the United Kingdom as a wholly-owned subsidiary of Aclaris Therapeutics, Inc. On March 24, 2016, Vixen Pharmaceuticals, Inc. (“Vixen”) became a wholly-owned subsidiary of Aclaris Therapeutics, Inc. (see Note 12). Aclaris Therapeutics, Inc., together with ATIL and Vixen, are referred to collectively as the “Company”. The Company is a clinical‑stage biotechnology company focused on identifying, developing and commercializing innovative and differentiated drugs to address significant unmet needs in dermatology. The Company’s lead drug candidate, A-101 40% Topical Solution, is a proprietary high‑concentration formulation of hydrogen peroxide topical solution that the Company is developing as a prescription treatment for seborrheic keratosis (“SK”), a common non‑malignant skin tumor. The Company has completed three Phase 3 clinical trials of A-101 40% Topical Solution in patients with SK, and submitted a New Drug Application (“NDA”) to the U.S. Food and Drug Administration (“FDA”) in February 2017. Initial Public Offering On October 6, 2015, the Company’s registration statement on Form S-1 relating to its initial public offering of its common stock (the “IPO”) was declared effective by the Securities and Exchange Commission (“SEC”). The Company’s common stock began trading on the NASDAQ Global Select Market on October 7, 2015. The IPO closed on October 13, 2015, and 5,000,000 shares of common stock were sold at a price to the public of $11.00 per share, for aggregate gross proceeds of $55,000. In addition, upon the closing of the IPO, all of the Company’s outstanding convertible preferred stock was converted into an aggregate total of 11,677,076 shares of common stock. The conversion of the convertible preferred stock was a non-cash transaction which has been excluded from the Consolidated Statements of Cash Flows. On October 12, 2015, the underwriters of the IPO exercised in full their option to purchase additional shares, and on October 13, 2015, the Company sold 750,000 additional shares of common stock at a price to the public of $11.00 per share, for aggregate gross proceeds of $8,250. The Company paid underwriting discounts and commissions of $4,428 to the underwriters in connection with the IPO, including the underwriters’ exercise of their option to purchase additional shares. In addition, the Company incurred expenses of $2,272 in connection with the IPO. The net offering proceeds received by the Company, after deducting underwriting discounts, commissions and offering expenses, were $56,550. Private Placement On June 2, 2016, pursuant to a securities purchase agreement with certain accredited investors dated May 27, 2016, the Company closed a private placement in which it sold an aggregate of 1,081,082 shares of common stock at a price of $18.50 per share, for gross proceeds of $20,000. The Company incurred placement agent fees of $1,300 and expenses of $153 in connection with the private placement. The net offering proceeds received by the Company, after deducting placement agent fees and transaction expenses, were $18,547. Follow-On Offering On November 13, 2016, the Company’s registration statement on Form S-3 was declared effective by the SEC. On November 17, 2016, the Company entered into an underwriting agreement with representatives of the underwriters, to issue and sell 4,000,000 shares of common stock pursuant to the registration statement filed on Form S-3 (the “Follow-On Offering”). The shares of common stock were sold to the public at a price of $22.75 per share, for gross proceeds of $91,000. On November 17, 2016, the underwriters of the Follow-On Offering exercised in full their option to purchase 600,000 additional shares of common stock at a price to the public of $22.75 per share, for gross proceeds of $13,650. The Company paid underwriting discounts and commissions of $6,279 to the underwriters in connection with the Follow-On Offering, including the underwriters’ exercise of their option to purchase additional shares. In addition, the Company incurred expenses of $188 in connection with the Follow-On Offering. The net offering proceeds received by the Company, after deducting underwriting discounts, commissions and offering expenses, were $98,158. Liquidity The Company’s consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities in the ordinary course of business. At December 31, 2016, the Company had cash, cash equivalents and marketable securities of $174,134 and an accumulated deficit of $90,912. The Company has not generated any product revenues and has not achieved profitable operations. There is no assurance that profitable operations will ever be achieved, and, if achieved, will be sustained on a continuing basis. In addition, development activities, clinical and pre-clinical testing, and commercialization of the Company’s drug candidates will require significant additional financing. The Company expects that its cash, cash equivalents and marketable securities as of December 31, 2016, will be sufficient to fund its operations for a period greater than 12 months from the date of issuance of these consolidated financial statements based on its current operating assumptions. The future viability of the Company is dependent on its ability to generate cash from operating activities or to raise additional capital to finance its operations. The Company’s failure to raise capital as and when needed could have a negative impact on its financial condition and ability to pursue its business strategies.

1. Organization and Nature of Business

Aclaris Therapeutics, Inc. was incorporated under the laws of the State of Delaware in 2012. On July 17, 2015, Aclaris Therapeutics International Limited (“ATIL”) was established under the laws of the United Kingdom as a wholly-owned subsidiary of Aclaris Therapeutics, Inc. On March 24, 2016, Vixen Pharmaceuticals, Inc. (“Vixen”) became a wholly-owned subsidiary of Aclaris Therapeutics, Inc. (see Note 12). Aclaris Therapeutics, Inc., together with ATIL and Vixen, are referred to collectively as the “Company”. The Company is a clinical‑stage biotechnology company focused on identifying, developing and commercializing innovative and differentiated drugs to address significant unmet needs in dermatology. The Company’s lead drug candidate, A-101 40% Topical Solution, is a proprietary high‑concentration formulation of hydrogen peroxide topical solution that the Company is developing as a prescription treatment for seborrheic keratosis (“SK”), a common non‑malignant skin tumor. The Company has completed three Phase 3 clinical trials of A-101 40% Topical Solution in patients with SK, and submitted a New Drug Application (“NDA”) to the U.S. Food and Drug Administration (“FDA”) in February 2017.

Initial Public Offering

On October 6, 2015, the Company’s registration statement on Form S-1 relating to its initial public offering of its common stock (the “IPO”) was declared effective by the Securities and Exchange Commission (“SEC”). The Company’s common stock began trading on the NASDAQ Global Select Market on October 7, 2015. The IPO closed on October 13, 2015, and 5,000,000 shares of common stock were sold at a price to the public of $11.00 per share, for aggregate gross proceeds of $55,000. In addition, upon the closing of the IPO, all of the Company’s outstanding convertible preferred stock was converted into an aggregate total of 11,677,076 shares of common stock. The conversion of the convertible preferred stock was a non-cash transaction which has been excluded from the Consolidated Statements of Cash Flows.

On October 12, 2015, the underwriters of the IPO exercised in full their option to purchase additional shares, and on October 13, 2015, the Company sold 750,000 additional shares of common stock at a price to the public of $11.00 per share, for aggregate gross proceeds of $8,250.

The Company paid underwriting discounts and commissions of $4,428 to the underwriters in connection with the IPO, including the underwriters’ exercise of their option to purchase additional shares. In addition, the Company incurred expenses of $2,272 in connection with the IPO. The net offering proceeds received by the Company, after deducting underwriting discounts, commissions and offering expenses, were $56,550.

Private Placement

On June 2, 2016, pursuant to a securities purchase agreement with certain accredited investors dated May 27, 2016, the Company closed a private placement in which it sold an aggregate of 1,081,082 shares of common stock at a price of $18.50 per share, for gross proceeds of $20,000. The Company incurred placement agent fees of $1,300 and expenses of $153 in connection with the private placement. The net offering proceeds received by the Company, after deducting placement agent fees and transaction expenses, were $18,547.

Follow-On Offering

On November 13, 2016, the Company’s registration statement on Form S-3 was declared effective by the SEC. On November 17, 2016, the Company entered into an underwriting agreement with representatives of the underwriters, to issue and sell 4,000,000 shares of common stock pursuant to the registration statement filed on Form S-3 (the “Follow-On Offering”). The shares of common stock were sold to the public at a price of $22.75 per share, for gross proceeds of $91,000. On November 17, 2016, the underwriters of the Follow-On Offering exercised in full their option to purchase 600,000 additional shares of common stock at a price to the public of $22.75 per share, for gross proceeds of $13,650.

The Company paid underwriting discounts and commissions of $6,279 to the underwriters in connection with the Follow-On Offering, including the underwriters’ exercise of their option to purchase additional shares. In addition, the Company incurred expenses of $188 in connection with the Follow-On Offering. The net offering proceeds received by the Company, after deducting underwriting discounts, commissions and offering expenses, were $98,158.

Liquidity

The Company’s consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities in the ordinary course of business. At December 31, 2016, the Company had cash, cash equivalents and marketable securities of $174,134 and an accumulated deficit of $90,912. The Company has not generated any product revenues and has not achieved profitable operations. There is no assurance that profitable operations will ever be achieved, and, if achieved, will be sustained on a continuing basis. In addition, development activities, clinical and pre-clinical testing, and commercialization of the Company’s drug candidates will require significant additional financing. The Company expects that its cash, cash equivalents and marketable securities as of December 31, 2016, will be sufficient to fund its operations for a period greater than 12 months from the date of issuance of these consolidated financial statements based on its current operating assumptions. The future viability of the Company is dependent on its ability to generate cash from operating activities or to raise additional capital to finance its operations. The Company’s failure to raise capital as and when needed could have a negative impact on its financial condition and ability to pursue its business strategies.