Common Stock	3 Months Ended
Mar. 31, 2020
Equity [Abstract]
Common Stock	(7) Common Stock As of March 31, 2020, the Company had 50,000,000 authorized shares of common stock, $0.001 par value, of which 16,080,616 shares were issued and outstanding. Reverse Stock Split – February 2020 On February 13, 2020, the holders of a majority of the Company’s outstanding shares of common stock approved the reverse stock split and gave the Company’s board of directors discretionary authority to select a ratio for the split ranging from 1-for-5 to 1-for-15. The Company’s board of directors approved the reverse stock split at a ratio of 1-for-10 on February 13, 2020. On February 19, 2020, the Company effected a reverse stock split of its outstanding shares of common stock at a ratio of one-for-ten pursuant to a Certificate of Amendment to its Certificate of Incorporation filed with the Secretary of State of the State of Delaware. The reverse stock split was reflected on Nasdaq beginning with the opening of trading on February 20, 2020. The primary purpose of the reverse stock split was to enable the Company to regain compliance with the $1.00 minimum bid price requirement for continued listing on Nasdaq. The reverse stock split affected all issued and outstanding shares of the Company’s common stock, as well as the number of authorized shares of the Company’s common stock and the number of shares of common stock available for issuance under the Company’s equity incentive plans. The reverse stock split reduced the number of shares of the Company’s issued and outstanding common stock from approximately 160.8 million to approximately 16.1 million. In addition, the reverse stock split effected a reduction in the number of shares of the Company’s common stock issuable upon the exercise of stock options and warrants outstanding immediately prior to the reverse stock split, with a proportional increase in the respective exercise prices. The reverse stock split proportionately reduced the number of authorized shares of the Company’s common stock from 500.0 million shares to 50.0 million shares. The reverse stock split did not change the par value of the Company’s common stock or the authorized number of shares of the Company’s preferred stock. All share and per share amounts disclosed give effect to the reverse stock split on a retroactive basis. Public Offering – April 2019 In April 2019, the Company completed an underwritten public offering of 2,173,913 shares of its common stock and warrants to purchase an aggregate of 2,500,000 shares of its common stock (“the Offering Warrants”), including warrants to purchase an aggregate of 326,086 shares of its common stock sold pursuant to the underwriter’s partial exercise of its overallotment option, at the public offering price of $11.40 per share and $0.10 per warrant for gross proceeds of approximately $25.0 million. The Offering Warrants were immediately exercisable upon issuance at an exercise price of $12.50 per share, subject to adjustment in certain circumstances, and will expire two years from the date of issuance upon their scheduled expiration in April 2021. Any Offering Warrants that have not been exercised for cash prior to their expiration shall be automatically exercised via cashless exercise on the expiration date. The shares and warrants were issued separately and are separately transferable. An entity affiliated with New Enterprise Associates purchased 434,782 shares and warrants to purchase an aggregate of 434,782 shares in this offering at the same public offering price per share as the other investors. At such time, entities affiliated with New Enterprise Associates (collectively) beneficially held more than 5% of the Company’s voting securities. The net offering proceeds to the Company were approximately $22.8 million after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company. As of March 31, 2020, Offering Warrants to purchase 2,500,000 shares of the Company’s common stock were outstanding. The Company determined the shares of common stock and the Offering Warrants represented freestanding financial instruments. In addition, the Company conducted an assessment of the classification of the Offering Warrants and, based on their terms, concluded the Offering Warrants are equity-classified. Accordingly, the net offering proceeds of $22.8 million have been recorded within stockholders’ equity (deficit). Sales Agreement with SVB Leerink In February 2018, the Company entered into the Leerink Sales Agreement, pursuant to which the Company may issue and sell shares of its common stock from time to time up to an aggregate amount of $50.0 million, at its option, through SVB Leerink as its sales agent, with any sales of common stock through SVB Leerink being made by any method that is deemed an “at-the-market offering” as defined in Rule 415 promulgated under the Securities Act of 1933, as amended (the “Securities Act”), or in other transactions pursuant to an effective shelf registration statement on Form S-3. The Company agreed to pay SVB Leerink a commission of up to 3% of the gross proceeds of any sales of common stock pursuant to the Leerink Sales Agreement. In the fourth quarter of 2018, the Company sold 470,777 shares pursuant to the Leerink Sales Agreement, resulting in approximately $10.3 million in proceeds, net of commissions. In February 2019, the Company sold 1,251,555 shares pursuant to the Leerink Sales Agreement, resulting in proceeds of approximately $7.5 million, net of commissions. As of March 31, 2020, approximately $32 million was available for issuance in connection with future stock sales pursuant to the Leerink Sales Agreement. Settlement Warrants On July 16, 2018, the Company issued and delivered 200,000 warrants to purchase shares of its common stock that the Company agreed to issue in connection with the settlement of the former 2013 class action lawsuit (the “Settlement Warrants”). The Settlement Warrants were exercisable for a one-year period after the date of issuance at an exercise price equal to $30.00 per share. All 200,000 Settlement Warrants expired on July 15, 2019 as none of the warrants had been exercised during the one-year exercise period. Universal Shelf Registration Statement On November 30, 2017, the Company filed a shelf registration statement on Form S-3 with the SEC, which covers the offering, issuance and sale of up to $200.0 million of its common stock, preferred stock, debt securities, warrants and/or units (the “2017 Shelf”). The 2017 Shelf (File No. 333-221873) was declared effective by the SEC on December 15, 2017 and was filed to replace the Company’s then existing shelf registration statement, which was terminated. Private Placement – May 2016 In May 2016, the Company entered into a securities purchase agreement with a select group of qualified institutional buyers, institutional accredited investors and accredited investors pursuant to which the Company sold 1,764,242 units, at a price of $9.65 per unit, for gross proceeds of approximately $17.0 million. Each unit consisted of one share of the Company’s common stock and a warrant to purchase one share of the Company’s common stock (the “PIPE Warrants”). The PIPE Warrants have an exercise price of $10.00 per share and are exercisable for a period of five years from the date of issuance until their scheduled expiration in May 2021. Certain of the Company’s directors and executive officers purchased an aggregate of 54,402 units in this offering at the same price as the other investors. The net offering proceeds to the Company were approximately $15.4 million after deducting placement agent fees and other offering expenses payable by the Company. As of March 31, 2020, PIPE Warrants exercisable for 80,309 shares of common stock had been exercised, for approximately $0.8 million in cash proceeds, and PIPE Warrants exercisable for 1,683,933 shares of common stock were outstanding.

Common Stock

3 Months Ended

Mar. 31, 2020

(7) Common Stock

As of March 31, 2020, the Company had 50,000,000 authorized shares of common stock, $0.001 par value, of which 16,080,616 shares were issued and outstanding.

Reverse Stock Split – February 2020

On February 13, 2020, the holders of a majority of the Company’s outstanding shares of common stock approved the reverse stock split and gave the Company’s board of directors discretionary authority to select a ratio for the split ranging from 1-for-5 to 1-for-15. The Company’s board of directors approved the reverse stock split at a ratio of 1-for-10 on February 13, 2020. On February 19, 2020, the Company effected a reverse stock split of its outstanding shares of common stock at a ratio of one-for-ten pursuant to a Certificate of Amendment to its Certificate of Incorporation filed with the Secretary of State of the State of Delaware. The reverse stock split was reflected on Nasdaq beginning with the opening of trading on February 20, 2020. The primary purpose of the reverse stock split was to enable the Company to regain compliance with the $1.00 minimum bid price requirement for continued listing on Nasdaq.

The reverse stock split affected all issued and outstanding shares of the Company’s common stock, as well as the number of authorized shares of the Company’s common stock and the number of shares of common stock available for issuance under the Company’s equity incentive plans. The reverse stock split reduced the number of shares of the Company’s issued and outstanding common stock from approximately 160.8 million to approximately 16.1 million. In addition, the reverse stock split effected a reduction in the number of shares of the Company’s common stock issuable upon the exercise of stock options and warrants outstanding immediately prior to the reverse stock split, with a proportional increase in the respective exercise prices. The reverse stock split proportionately reduced the number of authorized shares of the Company’s common stock from 500.0 million shares to 50.0 million shares. The reverse stock split did not change the par value of the Company’s common stock or the authorized number of shares of the Company’s preferred stock. All share and per share amounts disclosed give effect to the reverse stock split on a retroactive basis.

Public Offering – April 2019

In April 2019, the Company completed an underwritten public offering of 2,173,913 shares of its common stock and warrants to purchase an aggregate of 2,500,000 shares of its common stock (“the Offering Warrants”), including warrants to purchase an aggregate of 326,086 shares of its common stock sold pursuant to the underwriter’s partial exercise of its overallotment option, at the public offering price of $11.40 per share and $0.10 per warrant for gross proceeds of approximately $25.0 million. The Offering Warrants were immediately exercisable upon issuance at an exercise price of $12.50 per share, subject to adjustment in certain circumstances, and will expire two years from the date of issuance upon their scheduled expiration in April 2021. Any Offering Warrants that have not been exercised for cash prior to their expiration shall be automatically exercised via cashless exercise on the expiration date. The shares and warrants were issued separately and are separately transferable. An entity affiliated with New Enterprise Associates purchased 434,782 shares and warrants to purchase an aggregate of 434,782 shares in this offering at the same public offering price per share as the other investors. At such time, entities affiliated with New Enterprise Associates (collectively) beneficially held more than 5% of the Company’s voting securities. The net offering proceeds to the Company were approximately $22.8 million after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company. As of March 31, 2020, Offering Warrants to purchase 2,500,000 shares of the Company’s common stock were outstanding. The Company determined the shares of common stock and the Offering Warrants represented freestanding financial instruments. In addition, the Company conducted an assessment of the classification of the Offering Warrants and, based on their terms, concluded the Offering Warrants are equity-classified. Accordingly, the net offering proceeds of $22.8 million have been recorded within stockholders’ equity (deficit).

Sales Agreement with SVB Leerink

In February 2018, the Company entered into the Leerink Sales Agreement, pursuant to which the Company may issue and sell shares of its common stock from time to time up to an aggregate amount of $50.0 million, at its option, through SVB Leerink as its sales agent, with any sales of common stock through SVB Leerink being made by any method that is deemed an “at-the-market offering” as defined in Rule 415 promulgated under the Securities Act of 1933, as amended (the “Securities Act”), or in other transactions pursuant to an effective shelf registration statement on Form S-3. The Company agreed to pay SVB Leerink a commission of up to 3% of the gross proceeds of any sales of common stock pursuant to the Leerink Sales Agreement. In the fourth quarter of 2018, the Company sold 470,777 shares pursuant to the Leerink Sales Agreement, resulting in approximately $10.3 million in proceeds, net of commissions. In February 2019, the Company sold 1,251,555 shares pursuant to the Leerink Sales Agreement, resulting in proceeds of approximately $7.5 million, net of commissions. As of March 31, 2020, approximately $32 million was available for issuance in connection with future stock sales pursuant to the Leerink Sales Agreement.

Settlement Warrants

On July 16, 2018, the Company issued and delivered 200,000 warrants to purchase shares of its common stock that the Company agreed to issue in connection with the settlement of the former 2013 class action lawsuit (the “Settlement Warrants”). The Settlement Warrants were exercisable for a one-year period after the date of issuance at an exercise price equal to $30.00 per share. All 200,000 Settlement Warrants expired on July 15, 2019 as none of the warrants had been exercised during the one-year exercise period.

Universal Shelf Registration Statement

On November 30, 2017, the Company filed a shelf registration statement on Form S-3 with the SEC, which covers the offering, issuance and sale of up to $200.0 million of its common stock, preferred stock, debt securities, warrants and/or units (the “2017 Shelf”). The 2017 Shelf (File No. 333-221873) was declared effective by the SEC on December 15, 2017 and was filed to replace the Company’s then existing shelf registration statement, which was terminated.

Private Placement – May 2016

In May 2016, the Company entered into a securities purchase agreement with a select group of qualified institutional buyers, institutional accredited investors and accredited investors pursuant to which the Company sold 1,764,242 units, at a price of $9.65 per unit, for gross proceeds of approximately $17.0 million. Each unit consisted of one share of the Company’s common stock and a warrant to purchase one share of the Company’s common stock (the “PIPE Warrants”). The PIPE Warrants have an exercise price of $10.00 per share and are exercisable for a period of five years from the date of issuance until their scheduled expiration in May 2021. Certain of the Company’s directors and executive officers purchased an aggregate of 54,402 units in this offering at the same price as the other investors. The net offering proceeds to the Company were approximately $15.4 million after deducting placement agent fees and other offering expenses payable by the Company. As of March 31, 2020, PIPE Warrants exercisable for 80,309 shares of common stock had been exercised, for approximately $0.8 million in cash proceeds, and PIPE Warrants exercisable for 1,683,933 shares of common stock were outstanding.