Stockholders' Equity	9 Months Ended
Sep. 30, 2020
Equity [Abstract]
Stockholders' Equity	9. Stockholders’ Equity In October 2020, the Company issued 2,939,552 shares of its common stock to Vifor at a price per share of $17.0094 for an aggregate investment of $50,000 in connection with the license agreement entered into with Vifor (see Note 16, Subsequent Events). In June 2020, as a result of the completion of the one-year vesting period, an aggregate of 24,000 restricted stock units of members of the Board of Directors vested and were settled in shares of the Company’s common stock (see Note 13, Stock-Based Compensation). In April and June 2020, as a result of the achievement of certain performance targets, an aggregate of 95,834 restricted stock units of various executive officers vested and were settled in shares of the Company’s common stock (see Note 13, Stock-Based Compensation). In August 2019, the Company entered into a Non-Exclusive License Agreement, or the Enteris License Agreement, with Enteris Biopharma, Inc., or Enteris (see Note 15, Commitments and Contingencies for additional information regarding the License Agreement). As consideration for the licensed rights under the Enteris License Agreement, the Company paid an upfront fee equal to $8,000, consisting of $4,000 in cash and $4,000 in shares of the Company’s common stock. In connection with the Enteris License Agreement, in August 2019, the Company entered into a Common Stock Purchase Agreement, or the Enteris Purchase Agreement, with Enteris and its affiliate, EBP Holdco LLC, collectively referred to as Purchaser, pursuant to which the Company issued and sold to Purchaser 170,793 shares of its common stock in a private placement in satisfaction of the $4,000 portion of the upfront fee payable in shares of the Company’s common stock pursuant to the Enteris License Agreement, and for no additional consideration, based on a purchase price of $23.42 per share, which was equal to the 30-day volume weighted average price of the Company’s common stock on August 20, 2019. In addition, if the Company exercises its right, but not obligation, to terminate its obligation to pay any royalties under the Enteris License Agreement in exchange for a lump sum payment in cash, it may elect to make 50% of the payment in stock by issuing additional shares of the Company’s common stock valued at the 30-day volume weighted average price of the Company’s common stock as of such exercise. Pursuant to its obligations under the Enteris Purchase Agreement, the Company effected the registration and sale of the shares issued and sold to Purchaser thereunder in accordance with the applicable requirements of the Securities Act of 1933, as amended, or the Securities Act, through the filing of an automatic shelf registration statement on Form S-3ASR (File No. 333-233666) with the SEC on September 9, 2019. In addition, the Enteris Purchase Agreement includes customary representations, warranties and covenants by the Company (see Note 15, Commitments and Contingencies). In July 2019, the Company entered into an underwriting agreement with J.P. Morgan Securities LLC and Jefferies LLC, as representatives of the several underwriters named therein, relating to the issuance and sale by the Company of 6,325,000 shares of its common stock, which included the exercise of the underwriters’ option to purchase 825,000 additional shares of common stock, at a public offering price of $23.00 per share. The Company closed this offering on July 29, 2019, including the full exercise of the underwriters’ option to purchase 825,000 additional shares of common stock. As of September 30, 2019, the Company received net proceeds of approximately $136,525, after deducting $8,950 of underwriting discounts and commissions and estimated offering expenses payable by the Company. This offering was made pursuant to the Company’s Shelf Registration Statement on Form S-3 (File No. 333-230333), or the Shelf Registration Statement, filed with the SEC on March 15, 2019 and declared effective on April 4, 2019, and a related prospectus supplement dated July 24, 2019, which was filed with the SEC on July 25, 2019. The Shelf Registration Statement provided for aggregate offerings of up to $300,000 of common stock, preferred stock, debt securities, warrants or any combination thereof. The securities registered under the Shelf Registration Statement include unsold securities that had been registered under the Company’s previous shelf registration statement (File No. 333-216657) that was declared effective on March 24, 2017. In May 2019, as a result of the achievement of a clinical performance target, an aggregate of 74,166 restricted stock units of various executive officers vested and were settled in shares of the Company’s common stock (see Note 13, Stock-Based Compensation). On March 20, 2019, or the Effective Date, the Company entered into a consulting agreement with an existing stockholder. In accordance with the agreement, the stockholder provided various consulting services to the Company in exchange for 10,195 unregistered shares of the Company’s common stock. The closing price of the Company’s common stock on the Effective Date was $19.37 per share. The services provided by the consultant were performed during the six-month period following the Effective Date. During the three and nine months ended September 30, 2019, stock-based compensation expense of $98 and $197, respectively, was recognized in the Condensed Statement of Comprehensive Loss, all of which was related to G&A expense.

Stockholders' Equity

9 Months Ended

Sep. 30, 2020

9. Stockholders’ Equity

In October 2020, the Company issued 2,939,552 shares of its common stock to Vifor at a price per share of $17.0094 for an aggregate investment of $50,000 in connection with the license agreement entered into with Vifor (see Note 16, Subsequent Events).

In June 2020, as a result of the completion of the one-year vesting period, an aggregate of 24,000 restricted stock units of members of the Board of Directors vested and were settled in shares of the Company’s common stock (see Note 13, Stock-Based Compensation).

In April and June 2020, as a result of the achievement of certain performance targets, an aggregate of 95,834 restricted stock units of various executive officers vested and were settled in shares of the Company’s common stock (see Note 13, Stock-Based Compensation).

In August 2019, the Company entered into a Non-Exclusive License Agreement, or the Enteris License Agreement, with Enteris Biopharma, Inc., or Enteris (see Note 15, Commitments and Contingencies for additional information regarding the License Agreement). As consideration for the licensed rights under the Enteris License Agreement, the Company paid an upfront fee equal to $8,000, consisting of $4,000 in cash and $4,000 in shares of the Company’s common stock. In connection with the Enteris License Agreement, in August 2019, the Company entered into a Common Stock Purchase Agreement, or the Enteris Purchase Agreement, with Enteris and its affiliate, EBP Holdco LLC, collectively referred to as Purchaser, pursuant to which the Company issued and sold to Purchaser 170,793 shares of its common stock in a private placement in satisfaction of the $4,000 portion of the upfront fee payable in shares of the Company’s common stock pursuant to the Enteris License Agreement, and for no additional consideration, based on a purchase price of $23.42 per share, which was equal to the 30-day volume weighted average price of the Company’s common stock on August 20, 2019. In addition, if the Company exercises its right, but not obligation, to terminate its obligation to pay any royalties under the Enteris License Agreement in exchange for a lump sum payment in cash, it may elect to make 50% of the payment in stock by issuing additional shares of the Company’s common stock valued at the 30-day volume weighted average price of the Company’s common stock as of such exercise. Pursuant to its obligations under the Enteris Purchase Agreement, the Company effected the registration and sale of the shares issued and sold to Purchaser thereunder in accordance with the applicable requirements of the Securities Act of 1933, as amended, or the Securities Act, through the filing of an automatic shelf registration statement on Form S-3ASR (File No. 333-233666) with the SEC on September 9, 2019. In addition, the Enteris Purchase Agreement includes customary representations, warranties and covenants by the Company (see Note 15, Commitments and Contingencies).

In July 2019, the Company entered into an underwriting agreement with J.P. Morgan Securities LLC and Jefferies LLC, as representatives of the several underwriters named therein, relating to the issuance and sale by the Company of 6,325,000 shares of its common stock, which included the exercise of the underwriters’ option to purchase 825,000 additional shares of common stock, at a public offering price of $23.00 per share. The Company closed this offering on July 29, 2019, including the full exercise of the underwriters’ option to purchase 825,000 additional shares of common stock. As of September 30, 2019, the Company received net proceeds of approximately $136,525, after deducting $8,950 of underwriting discounts and commissions and estimated offering expenses payable by the Company.

This offering was made pursuant to the Company’s Shelf Registration Statement on Form S-3 (File No. 333-230333), or the Shelf Registration Statement, filed with the SEC on March 15, 2019 and declared effective on April 4, 2019, and a related prospectus supplement dated July 24, 2019, which was filed with the SEC on July 25, 2019. The Shelf Registration Statement provided for aggregate offerings of up to $300,000 of common stock, preferred stock, debt securities, warrants or any combination thereof. The securities registered under the Shelf Registration Statement include unsold securities that had been registered under the Company’s previous shelf registration statement (File No. 333-216657) that was declared effective on March 24, 2017.

In May 2019, as a result of the achievement of a clinical performance target, an aggregate of 74,166 restricted stock units of various executive officers vested and were settled in shares of the Company’s common stock (see Note 13, Stock-Based Compensation).

On March 20, 2019, or the Effective Date, the Company entered into a consulting agreement with an existing stockholder. In accordance with the agreement, the stockholder provided various consulting services to the Company in exchange for 10,195 unregistered shares of the Company’s common stock. The closing price of the Company’s common

stock on the Effective Date was $19.37 per share. The services provided by the consultant were performed during the six-month period following the Effective Date. During the three and nine months ended September 30, 2019, stock-based compensation expense of $98 and $197, respectively, was recognized in the Condensed Statement of Comprehensive Loss, all of which was related to G&A expense.