Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 147,835	$ 75,975
Prepaid expenses and other current assets	2,238	1,156
Total current assets	150,073	77,131
Restricted cash	60	20
Other assets	10
Total assets	150,143	77,151
Current liabilities:
Accounts payable	93	1,373
Accrued expenses and other current liabilities	6,632	969
Total current liabilities	6,725	2,342
Other liabilities	34
Total liabilities	6,759	2,342
Commitments and contingencies (Note 10)
Redeemable convertible preferred stock (Series A and B), $0.0001 par value; no shares authorized, issued and outstanding as of September 30, 2019; 64,730,410 shares authorized, issued and outstanding as of December 31, 2018; aggregate liquidation preference of $0 and $96,358 as of September 30, 2019 and December 31, 2018, respectively		124,728
Stockholders’ equity (deficit):
Common stock, $0.0001 par value, 150,000,000 shares authorized as of September 30, 2019 and 75,000,000 shares authorized as of December 31, 2018; 28,558,653 and 238,986 shares issued and outstanding as of September 30, 2019 and December 31, 2018, respectively	3
Additional paid-in capital	258,090	36,646
Accumulated deficit	(114,709)	(86,565)
Total stockholders’ equity (deficit)	143,384	(49,919)
Total liabilities, redeemable convertible preferred stock and stockholders’ equity (deficit)	$ 150,143	$ 77,151