Convertible Preferred Stock	3 Months Ended
Mar. 31, 2020
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	6. Convertible Preferred Stock In April 2018, the Company entered into the Series A Share Purchase Agreement (the “Series A SPA”), pursuant to which the investors committed to invest an aggregate amount of up to $60.0 million for the issuance of shares of Series A convertible preferred stock at a price of $1.00 per share. The initial closing occurred on April 16, 2018, and the Company issued 14,900,000 shares of Series A convertible preferred stock at a price per share of $1.00 for net cash proceeds of $14.7 million. In addition, a convertible note in the amount of $100,000 that was outstanding and automatically convertible in the Company’s next equity financing, converted into 100,000 shares of Series A convertible preferred stock upon the initial closing of the Series A financing. The investors also committed to purchase 15,000,000 and 30,000,000 shares of Series A convertible preferred stock at a price of $1.00 per share in second and third closings, respectively, contingent upon the achievement by the Company of certain development milestones and approval by the board of directors. The investors’ commitment to purchase and the Company’s commitment to sell shares of Series A convertible preferred stock represent a freestanding instrument accounted for at fair value and re-measured at each reporting date. For the three months ended March 31, 2020 and 2019, the Company recorded a gain of $0 and $437,000, respectively, for the revaluation of the convertible preferred stock liability within other income, net in the condensed consolidated statements of operations and comprehensive loss. In December 2018 and in June 2019, the Company and the Series A convertible preferred stockholders agreed to issue 9,000,000 and 20,000,000 shares of Series A convertible preferred stock at a price of $1.00 per share, respectively, related to the second and third closings. Aggregate net proceeds of $9.0 million were received in December 2018 and $20.0 million were received in June and July 2019. On October 25, 2019, the Company and the Series A preferred stockholders amended the Series A SPA, and the parties agreed that the Series A SPA would terminate upon consummation of the Company’s IPO. Upon the completion of the Company’s IPO on November 13, 2019, the remaining 16,000,000 shares of convertible preferred stock that were previously issuable under the third closing were no longer issuable. Accordingly, the preferred stock liability was extinguished and because the transaction occurred between related parties, the resulting $25.6 million was accounted for as a capital contribution by the preferred stockholders. Additionally, immediately prior to the completion of the Company’s IPO, all outstanding shares of convertible preferred stock automatically converted into 7,077,366 shares of common stock and the related carrying value was reclassified to common stock and additional paid-in capital. Accordingly, there were no shares of convertible preferred stock outstanding as of March 31, 2020 and December 31, 2019.

Convertible Preferred Stock

3 Months Ended

Mar. 31, 2020

Temporary Equity Disclosure [Abstract]

6. Convertible Preferred Stock

In April 2018, the Company entered into the Series A Share Purchase Agreement (the “Series A SPA”), pursuant to which the investors committed to invest an aggregate amount of up to $60.0 million for the issuance of shares of Series A convertible preferred stock at a price of $1.00 per share.

The initial closing occurred on April 16, 2018, and the Company issued 14,900,000 shares of Series A convertible preferred stock at a price per share of $1.00 for net cash proceeds of $14.7 million. In addition, a convertible note in the amount of $100,000 that was outstanding and automatically convertible in the Company’s next equity financing, converted into 100,000 shares of Series A convertible preferred stock upon the initial closing of the Series A financing. The investors also committed to purchase 15,000,000 and 30,000,000 shares of Series A convertible preferred stock at a price of $1.00 per share in second and third closings, respectively, contingent upon the achievement by the Company of certain development milestones and approval by the board of directors.

The investors’ commitment to purchase and the Company’s commitment to sell shares of Series A convertible preferred stock represent a freestanding instrument accounted for at fair value and re-measured at each reporting date. For the three months ended March 31, 2020 and 2019, the Company recorded a gain of $0 and $437,000, respectively, for the revaluation of the convertible preferred stock liability within other income, net in the condensed consolidated statements of operations and comprehensive loss.

In December 2018 and in June 2019, the Company and the Series A convertible preferred stockholders agreed to issue 9,000,000 and 20,000,000 shares of Series A convertible preferred stock at a price of $1.00 per share, respectively, related to the second and third closings. Aggregate net proceeds of $9.0 million were received in December 2018 and $20.0 million were received in June and July 2019.

On October 25, 2019, the Company and the Series A preferred stockholders amended the Series A SPA, and the parties agreed that the Series A SPA would terminate upon consummation of the Company’s IPO.

Upon the completion of the Company’s IPO on November 13, 2019, the remaining 16,000,000 shares of convertible preferred stock that were previously issuable under the third closing were no longer issuable. Accordingly, the preferred stock liability was extinguished and because the transaction occurred between related parties, the resulting $25.6 million was accounted for as a capital contribution by the preferred stockholders.

Additionally, immediately prior to the completion of the Company’s IPO, all outstanding shares of convertible preferred stock automatically converted into 7,077,366 shares of common stock and the related carrying value was reclassified to common stock and additional paid-in capital. Accordingly, there were no shares of convertible preferred stock outstanding as of March 31, 2020 and December 31, 2019.