CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 87,063	$ 135,897
Short-term marketable securities	198,571	416,033
Accounts receivable, net	20,595	13,896
Inventory	14,125	5,716
Prepaid expenses and other current assets	18,660	12,489
Total current assets	339,014	584,031
Long-term marketable securities	41,950	9,375
Long-term investments—restricted	3,110	3,102
Property and equipment, net	8,610	9,583
Operating lease assets	36,800	36,341
Total assets	429,484	642,432
Current liabilities:
Accounts payable	13,130	12,308
Accrued expenses and other current liabilities	80,773	55,227
Operating lease liabilities	2,870	2,457
Total current liabilities	96,773	69,992
Operating lease liabilities, net of current portion	27,991	28,764
Total liabilities	124,764	98,756
Commitments and contingencies (Note 16)
Stockholders' equity:
Preferred stock, $0.01 par value per share; 5,000,000 shares authorized; no shares issued or outstanding	0	0
Common stock, $0.01 par value per share; 125,000,000 shares authorized; 58,549,644 shares and 57,596,144 shares issued and outstanding as of December 31, 2021 and 2020, respectively	585	576
Additional paid-in capital	1,358,516	1,297,557
Accumulated other comprehensive income	51	11
Accumulated deficit	(1,054,432)	(754,468)
Total stockholders' equity	304,720	543,676
Total liabilities and stockholders' equity	$ 429,484	$ 642,432