Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders' Deficit (Unaudited) - USD ($) $ in Thousands | Total | Series A Redeemable Convertible Preferred Stock | Series B Redeemable Convertible Preferred Stock | Common Stock | Additional Paid in Capital | Other Comprehensive Income / (Loss) | Accumulated Deficit |
Beginning balance at Dec. 31, 2017 | $ (20,280) | | | $ 3 | $ 66 | | $ (20,349) |
Beginning balance, shares at Dec. 31, 2017 | | 9,008,919 | | | | | |
Beginning balance at Dec. 31, 2017 | | $ 17,178 | | | | | |
Beginning balance, shares at Dec. 31, 2017 | | | | 3,361,016 | | | |
Stock based compensation | 47 | | | | 47 | | |
Proceeds from Series B redeemable convertible preferred stock, net of issuance costs, shares | | | 7,890,466 | | | | |
Proceeds from Series B redeemable convertible preferred stock, net of issuance costs | | | $ 75,688 | | | | |
Issuance of Series B redeemable convertible preferred stock in connection with the conversion of convertible promissory notes and accrued interest | | | $ 11,027 | | | | |
Issuance of Series B redeemable convertible preferred stock in connection with the conversion of convertible promissory notes and accrued interest, shares | | | 1,147,205 | | | | |
Vesting of Series B redeemable convertible preferred stock in lieu of rent | | | $ 61 | | | | |
Issuance of Series B redeemable convertible preferred stock in connection with the facility lease agreement, shares | | | 114,437 | | | | |
Other comprehensive income | (16) | | | | | $ (16) | |
Net loss | (9,006) | | | | | | (9,006) |
Ending balance at Sep. 30, 2018 | (29,255) | | | $ 3 | 113 | (16) | (29,355) |
Ending balance, shares at Sep. 30, 2018 | | 9,008,919 | 9,152,108 | | | | |
Ending balance at Sep. 30, 2018 | | $ 17,178 | $ 86,776 | | | | |
Ending balance, shares at Sep. 30, 2018 | | | | 3,361,016 | | | |
Beginning balance at Jun. 30, 2018 | (26,738) | | | $ 3 | 93 | | (26,834) |
Beginning balance, shares at Jun. 30, 2018 | | 9,008,919 | 9,037,671 | | | | |
Beginning balance at Jun. 30, 2018 | | $ 17,178 | $ 86,715 | | | | |
Beginning balance, shares at Jun. 30, 2018 | | | | 3,361,016 | | | |
Stock based compensation | 20 | | | | 20 | | |
Vesting of Series B redeemable convertible preferred stock in lieu of rent | | | $ 61 | | | | |
Issuance of Series B redeemable convertible preferred stock in connection with the facility lease agreement, shares | | | 114,437 | | | | |
Other comprehensive income | (16) | | | | | (16) | |
Net loss | (2,521) | | | | | | (2,521) |
Ending balance at Sep. 30, 2018 | (29,255) | | | $ 3 | 113 | (16) | (29,355) |
Ending balance, shares at Sep. 30, 2018 | | 9,008,919 | 9,152,108 | | | | |
Ending balance at Sep. 30, 2018 | | $ 17,178 | $ 86,776 | | | | |
Ending balance, shares at Sep. 30, 2018 | | | | 3,361,016 | | | |
Beginning balance at Dec. 31, 2018 | (32,626) | | | $ 3 | 245 | (49) | (32,825) |
Beginning balance, shares at Dec. 31, 2018 | | 9,008,919 | 9,152,108 | | | | |
Beginning balance at Dec. 31, 2018 | | $ 17,178 | $ 86,868 | | | | |
Beginning balance, shares at Dec. 31, 2018 | | | | 3,412,366 | | | |
Exercise of stock options | 69 | | | $ 1 | 68 | | |
Exercise of stock options, shares | | | | 166,015 | | | |
Stock based compensation | 1,479 | | | | 1,479 | | |
Vesting of Series B redeemable convertible preferred stock in lieu of rent | | | $ 948 | | | | |
Conversion of redeemable convertible preferred stock to common stock | 104,994 | | | $ 18 | 104,976 | | |
Conversion of redeemable convertible preferred stock to common stock, shares | | (9,008,919) | (9,152,108) | | | | |
Conversion of redeemable convertible preferred stock to common stock | | $ (17,178) | $ (87,816) | | | | |
Conversion of redeemable convertible preferred stock to common stock, shares | | | | 18,161,027 | | | |
Initial public offering of common stock, net of issuance costs | 77,827 | | | $ 5 | 77,822 | | |
Initial public offering of common stock, net of issuance costs, shares | | | | 5,073,800 | | | |
Exercise of stock warrant, shares | | | | 27,941 | | | |
Other comprehensive income | 145 | | | | | 145 | |
Net loss | (24,601) | | | | | | (24,601) |
Ending balance at Sep. 30, 2019 | 127,287 | | | $ 27 | 184,590 | 96 | (57,426) |
Ending balance, shares at Sep. 30, 2019 | | 0 | 0 | | | | |
Ending balance, shares at Sep. 30, 2019 | | | | 26,841,149 | | | |
Beginning balance at Jun. 30, 2019 | 136,217 | | | $ 27 | 183,678 | 80 | (47,568) |
Beginning balance, shares at Jun. 30, 2019 | | | | 26,841,149 | | | |
Stock based compensation | 912 | | | | 912 | | |
Other comprehensive income | 16 | | | | | 16 | |
Net loss | (9,858) | | | | | | (9,858) |
Ending balance at Sep. 30, 2019 | $ 127,287 | | | $ 27 | $ 184,590 | $ 96 | $ (57,426) |
Ending balance, shares at Sep. 30, 2019 | | 0 | 0 | | | | |
Ending balance, shares at Sep. 30, 2019 | | | | 26,841,149 | | | |