CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 128,023	$ 85,449
Short-term investments	56,536
Accounts receivable, net	4,281	11,563
Inventory	5,711	4,648
Prepaid expenses and other current assets	2,473	3,824
Total current assets	197,024	105,484
Non-current assets:
Property and equipment, net	2,964	2,698
Long-term inventory	4,109	3,778
Right-of-use assets	28,829	29,781
Restricted cash	12,584	12,582
Total assets	245,510	154,323
Current liabilities:
Accounts payable	1,548	2,518
Accrued expenses and other current liabilities	13,967	20,929
Current portion of lease liabilities	1,425	1,327
Total current liabilities	16,940	24,774
Long-term liabilities:
Long-term lease liabilities - less current portion	27,930	28,673
Long-term debt	71,697	71,184
Total long-term liabilities	99,627	99,857
Total liabilities	116,567	124,631
Commitments and Contingencies (Note 14)
Stockholders' equity:
Common stock, $0.001 par value; 120,000,000 shares authorized as of June 30, 2020 and December 31, 2019; 55,831,021 and 36,086,254 shares issued and outstanding as of June 30, 2020 and December 31, 2019, respectively	56	36
Additional paid-in capital	469,627	325,112
Accumulated other comprehensive income	(17)
Accumulated deficit	(340,723)	(295,456)
Total stockholders' equity	128,943	29,692
Total liabilities and stockholders' equity	$ 245,510	$ 154,323