Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 101,597	$ 72,797
Prepaid expenses and other current assets	3,625	1,298
Total current assets	105,222	74,095
Property and equipment, net	9,583	10,546
Restricted cash	1,092	1,092
Other assets	59	38
Total assets	115,956	85,771
Current liabilities:
Accounts payable	4,533	1,263
Accrued expenses and other current liabilities	3,583	2,497
Deferred lease incentive, current portion	469	469
Total current liabilities	8,585	4,229
Deferred rent, excluding current portion	1,527	1,402
Deferred lease incentive, excluding current portion	3,638	3,990
Other liabilities, excluding current portion	78	150
Total liabilities	13,828	9,771
Commitments and contingencies (Note 10)
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.001 par value; 200,000,000 and 135,000,000 shares authorized as of September 30, 2019 and December 31, 2018, respectively; 23,340,419 and 2,791,764 shares issued as of September 30, 2019 and December 31, 2018, respectively; 22,557,871 and 1,587,953 shares outstanding as of September 30, 2019 and December 31, 2018, respectively	23	2
Additional paid-in capital	236,783	4,452
Accumulated deficit	(134,678)	(68,124)
Total stockholders’ equity (deficit)	102,128	(63,670)
Total liabilities, convertible preferred stock, and stockholders’ equity (deficit)	$ 115,956	85,771
Series A Convertible Preferred Stock
Current liabilities:
Convertible preferred stock		59,909
Series B Convertible Preferred Stock
Current liabilities:
Convertible preferred stock		$ 79,761