CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 133,245	$ 55,046
Short-term investments	72,818	73,243
Accounts receivable, net	5,903	3,300
Inventory and other deferred costs	6,268	4,606
Prepaid expenses and other current assets	5,359	3,383
Total current assets	223,593	139,578
Property and equipment, net	12,735	14,106
Operating lease right-of-use assets	10,632	1,845
Other long-term assets	1,852	1,762
Total assets	248,812	157,291
Current liabilities
Accounts payable	6,514	7,337
Accrued and other current liabilities	8,797	6,648
Contract liabilities	20,593	35,977
Total current liabilities	35,904	49,962
Long-term operating lease liabilities	8,897	639
Other long-term liabilities	471
Total liabilities	45,272	50,601
Commitments and Contingencies (Note 12)
Stockholders’ equity
Common stock, $0.0001 par value — 200,000,000 shares authorized; 38,790,189 and 31,243,029 shares issued and outstanding at September 30, 2020 and December 31, 2019, respectively	4	3
Additional paid-in capital	372,027	247,282
Accumulated other comprehensive income (loss)	37	(6)
Accumulated deficit	(168,528)	(140,589)
Total stockholders’ equity	203,540	106,690
Total liabilities and stockholders’ equity	$ 248,812	$ 157,291