Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Prepaid expenses and other current assets, related parties	$ 0	$ 82
Accounts payable, related parties	311	173
Accrued expenses, related parties	$ 1,847	$ 734
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, authorized shares	40,000,000	40,000,000
Preferred stock, issued shares	0	0
Preferred stock, outstanding shares	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, authorized shares	400,000,000	400,000,000
Common stock, issued shares	31,414,827	31,262,769
Common stock, outstanding shares	30,047,428	28,516,010