Common Stock	6 Months Ended
Jun. 30, 2019
Equity [Abstract]
Common Stock	6. Common Stock On December 3, 2018, the Company filed a universal shelf registration statement on Form S-3 (Registration No. 333-228661) with the SEC, which was declared effective on December 11, 2018, pursuant to which it registered for sale up to $200.0 million of any combination of its common stock, preferred stock, debt securities, warrants, rights and/or units from time to time and at prices and on terms that the Company may determine, including up to $50.0 million of its common stock available for issuance pursuant to an at-the-market offering program sales agreement that it entered into with Cantor Fitzgerald & Co. (“Cantor”). Under the sales agreement, Cantor may sell shares of the Company’s common stock by any method permitted by law deemed to be an “at the market” offering as defined in Rule 415 of the Securities Act, subject to the terms of the sales agreement. During the six months ended June 30, 2019, the Company sold 425,062 shares of its common stock under the sales agreement at an average price of approximately $12.73 per share for aggregate gross proceeds of approximately $5.4 million and net proceeds of approximately $5.3 million after deducting sales commissions. On June 12 2019, the Company entered into a securities purchase agreement with Novo Holdings A/S (“Novo”) to sell up to an aggregate of $10.0 million of its common stock, $0.001 par value per share, in two closings pursuant to the Company’s effective registration statement on Form S-3 (Registration No. 333-228661). The initial closing occurred on June 14, 2019 and consisted of 465,983 shares of common stock sold at a fair value price of $10.73 per share for gross proceeds of $5.0 million prior to deducting offering expenses. The second closing of $5.0 million will be triggered upon the earlier of (i) the Company’s public announcement of pharmacokinetic data from the lead-in cohort in its Phase 3 clinical trial of SPR994 (“SPR994 Data Disclosure Date”) or (ii) June 30, 2020, subject to the satisfaction of certain conditions set forth in the securities purchase agreement. Novo shall have no obligation to purchase the shares of common stock in the second closing, and the second closing shall not occur, if, prior to and continuing as of the SPR994 Data Disclosure Date, the Company has ceased all research and development (including clinical development) of SPR720. The number of shares to be sold in the second closing will be determined by the volume weighted average trading price (“VWAP”) of the Company’s common stock prior to the date of the second closing. Because the shares of common stock are being sold directly to Novo and not through a placement agent, underwriter or securities broker or dealer, the Company is not paying any underwriting discounts, commissions, concessions or similar compensation with respect to the sale. In June 2019, a holder of the Company’s Series A Convertible Preferred stock elected to convert 500 shares into 500,000 shares of the Company’s common stock, pursuant to such holder’s rights under the certificate of designation for such Series A Convertible Preferred Stock.

Common Stock

6 Months Ended

Jun. 30, 2019

6. Common Stock

On December 3, 2018, the Company filed a universal shelf registration statement on Form S-3 (Registration No. 333-228661) with the SEC, which was declared effective on December 11, 2018, pursuant to which it registered for sale up to $200.0 million of any combination of its common stock, preferred stock, debt securities, warrants, rights and/or units from time to time and at prices and on terms that the Company may determine, including up to $50.0 million of its common stock available for issuance pursuant to an at-the-market offering program sales agreement that it entered into with Cantor Fitzgerald & Co. (“Cantor”). Under the sales agreement, Cantor may sell shares of the Company’s common stock by any method permitted by law deemed to be an “at the market” offering as defined in Rule 415 of the Securities Act, subject to the terms of the sales agreement. During the six months ended June 30, 2019, the Company sold 425,062 shares of its common stock under the sales agreement at an average price of approximately $12.73 per share for aggregate gross proceeds of approximately $5.4 million and net proceeds of approximately $5.3 million after deducting sales commissions.

On June 12 2019, the Company entered into a securities purchase agreement with Novo Holdings A/S (“Novo”) to sell up to an aggregate of $10.0 million of its common stock, $0.001 par value per share, in two closings pursuant to the Company’s effective registration statement on Form S-3 (Registration No. 333-228661). The initial closing occurred on June 14, 2019 and consisted of 465,983 shares of common stock sold at a fair value price of $10.73 per share for gross proceeds of $5.0 million prior to deducting offering expenses. The second closing of $5.0 million will be triggered upon the earlier of (i) the Company’s public announcement of pharmacokinetic data from the lead-in cohort in its Phase 3 clinical trial of SPR994 (“SPR994 Data Disclosure Date”) or (ii) June 30, 2020, subject to the satisfaction of certain conditions set forth in the securities purchase agreement. Novo shall have no obligation to purchase the shares of common stock in the second closing, and the second closing shall not occur, if, prior to and continuing as of the SPR994 Data Disclosure Date, the Company has ceased all research and development (including clinical development) of SPR720. The number of shares to be sold in the second closing will be determined by the volume weighted average trading price (“VWAP”) of the Company’s common stock prior to the date of the second closing. Because the shares of common stock are being sold directly to Novo and not through a placement agent, underwriter or securities broker or dealer, the Company is not paying any underwriting discounts, commissions, concessions or similar compensation with respect to the sale.

In June 2019, a holder of the Company’s Series A Convertible Preferred stock elected to convert 500 shares into 500,000 shares of the Company’s common stock, pursuant to such holder’s rights under the certificate of designation for such Series A Convertible Preferred Stock.