Financings	12 Months Ended
Dec. 31, 2021
Text Block [Abstract]
Financings	2. Financings 2021 Loan and Security Agreement On August 6, 2021, the Company entered into a Loan and Security Agreement with Silicon Valley Bank and affiliates of Silicon Valley Bank (collectively, "SVB") (the "Loan and Security Agreement"). The Loan and Security Agreement provided for an initial term loan of $25.0 million funded at the closing ("Term A Tranche"), with an additional tranche of $25.0 million available if certain funding and clinical milestones were met by August 31, 2022 ("Term B Tranche"). Effective December 28, 2021, the Company, entered into a First Amendment (the “Amendment”) to the Loan and Security Agreement (the "Amended Loan and Security Agreement"). The Amended Loan and Security Agreement extends the interest-only period through August 31, 2022, and provides for an automatic extension through August 31, 2023, if certain funding and clinical milestones are met by August 31, 2022 (the “Amended Milestones”). The Amendment eliminated the Term B Tranche, which remained unfunded, leaving only the Term A Tranche (the "SVB Facility"). Under the Amended Loan and Security Agreement, the SVB Facility will mature on August 1, 2023; however, if the Company achieves the Amended Milestones on or prior to August 31, 2022, then the maturity will automatically extend to August 1, 2024. Please refer to Note 4, Debt, for further discussion of the Loan and Security Agreement and the Amended Loan and Security Agreement. February 2020 Public Offering On February 5, 2020, the Company issued and sold 27,826,086 shares of its common stock at an offering price to the public of $3.25 per share, for aggregate net proceeds of approximately $84.8 million after deducting underwriting discounts and offering expenses paid by the Company. The offering was made pursuant to the Company's effective registration statement on Form S-3ASR (File No. 333-232283) previously filed with the Securities and Exchange Commission (the “SEC”) and a prospectus supplement thereunder. On March 10, 2020, the underwriters exercised their option to purchase an additional 1,284,025 shares. The net proceeds were approximately $3.9 million after deducting underwriting discounts and offering expenses paid by us. At-the-Market Offering Program In June 2019, the Company entered into an Open Market Sale Agreement (the "Sales Agreement") with Jefferies, pursuant to which the Company may offer and sell, from time to time through Jefferies, shares of its common stock having an aggregate offering price of up to $100.0 million. Shares will be sold pursuant to the Company’s effective registration statement on Form S-3ASR (File No. 333-232283), as previously filed with the SEC. There were no sales under the Sales Agreement during the year ended December 31, 2021. During the year ended December 31, 2020, the Company issued and sold an aggregate of 2,814,673 shares for aggregate net proceeds of approximately $13.0 million after deducting underwriting discounts and offering expenses payable by us.

Financings

12 Months Ended

Dec. 31, 2021

2021 Loan and Security Agreement

On August 6, 2021, the Company entered into a Loan and Security Agreement with Silicon Valley Bank and affiliates of Silicon Valley Bank (collectively, "SVB") (the "Loan and Security Agreement"). The Loan and Security Agreement provided for an initial term loan of $25.0 million funded at the closing ("Term A Tranche"), with an additional tranche of $25.0 million available if certain funding and clinical milestones were met by August 31, 2022 ("Term B Tranche").

Effective December 28, 2021, the Company, entered into a First Amendment (the “Amendment”) to the Loan and Security Agreement (the "Amended Loan and Security Agreement").

The Amended Loan and Security Agreement extends the interest-only period through August 31, 2022, and provides for an automatic extension through August 31, 2023, if certain funding and clinical milestones are met by August 31, 2022 (the “Amended Milestones”). The Amendment eliminated the Term B Tranche, which remained unfunded, leaving only the Term A Tranche (the "SVB Facility"). Under the Amended Loan and Security Agreement, the SVB Facility will mature on August 1, 2023; however, if the Company achieves the Amended Milestones on or prior to August 31, 2022, then the maturity will automatically extend to August 1, 2024.

Please refer to Note 4, Debt, for further discussion of the Loan and Security Agreement and the Amended Loan and Security Agreement.

February 2020 Public Offering

On February 5, 2020, the Company issued and sold 27,826,086 shares of its common stock at an offering price to the public of $3.25 per share, for aggregate net proceeds of approximately $84.8 million after deducting underwriting discounts and offering expenses paid by the Company. The offering was made pursuant to the Company's effective registration statement on Form S-3ASR (File No. 333-232283) previously filed with the Securities and Exchange Commission (the “SEC”) and a prospectus supplement thereunder.

On March 10, 2020, the underwriters exercised their option to purchase an additional 1,284,025 shares. The net proceeds were approximately $3.9 million after deducting underwriting discounts and offering expenses paid by us.

At-the-Market Offering Program

In June 2019, the Company entered into an Open Market Sale Agreement (the "Sales Agreement") with Jefferies, pursuant to which the Company may offer and sell, from time to time through Jefferies, shares of its common stock having an aggregate offering price of up to $100.0 million. Shares will be sold pursuant to the Company’s effective registration statement on Form S-3ASR (File No. 333-232283), as previously filed with the SEC.

There were no sales under the Sales Agreement during the year ended December 31, 2021. During the year ended December 31, 2020, the Company issued and sold an aggregate of 2,814,673 shares for aggregate net proceeds of approximately $13.0 million after deducting underwriting discounts and offering expenses payable by us.