Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 29,906	$ 71,157
Restricted cash	316	527
Short-term investments	19,978
Accounts receivable, net	3,513	4,017
Inventory	4,155	3,597
Prepaid expenses and other current assets	2,889	2,556
Total current assets	60,757	81,854
Property and equipment, net	26,778	25,602
Other assets	6,190	249
Total assets	93,725	107,705
Current liabilities:
Accounts payable	4,789	5,379
Accrued expenses and other current liabilities	15,904	15,022
Facility financing obligation		11,298
Short-term note payable	5,028
Deferred revenue — current	32,503	36,885
Recognized loss on purchase commitments — current	7,394	6,657
Total current liabilities	65,618	75,241
Promissory notes	70,020	72,089
Accrued interest — promissory notes	2,002	6,835
Long-term Midcap credit facility	38,851
Senior convertible notes	5,000	19,099
Recognized loss on purchase commitments — long term	84,639	91,642
Operating lease liability	2,514
Deferred revenue — long term	8,344	10,680
Milestone rights liability	7,263	7,201
Total liabilities	284,251	282,787
Commitments and contingencies (Note 13)
Stockholders' deficit:
Undesignated preferred stock, $0.01 par value — 10,000,000 shares authorized; no shares issued or outstanding at December 31, 2019 and 2018
Common stock, $0.01 par value — 280,000,000 shares authorized, 211,787,573 and 187,029,967 shares issued and outstanding at December 31, 2019 and 2018, respectively	2,118	1,870
Additional paid-in capital	2,799,278	2,763,067
Accumulated other comprehensive loss	(19)	(19)
Accumulated deficit	(2,991,903)	(2,940,000)
Total stockholders' deficit	(190,526)	(175,082)
Total liabilities and stockholders' deficit	$ 93,725	$ 107,705