Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 38,868,000	$ 29,906,000
Restricted cash	316,000	316,000
Short-term investments	0	19,978,000
Accounts receivable, net	5,032,000	3,513,000
Inventory	3,231,000	4,155,000
Prepaid expenses and other current assets	1,901,000	2,889,000
Total current assets	49,348,000	60,757,000
Property and equipment, net	26,517,000	26,778,000
Other assets	4,347,000	6,190,000
Total assets	80,212,000	93,725,000
Current liabilities:
Accounts payable	6,731,000	4,789,000
Accrued expenses and other current liabilities	18,326,000	15,904,000
Short-term note payable	5,101,000	5,028,000
Deferred revenue — current	30,840,000	32,503,000
Recognized loss on purchase commitments — current	7,250,000	7,394,000
Total current liabilities	68,248,000	65,618,000
Promissory notes	70,022,000	70,020,000
Accrued interest — promissory notes	3,259,000	2,002,000
Long-term Midcap credit facility	38,893,000	38,851,000
Senior convertible notes	5,000,000	5,000,000
Recognized loss on purchase commitments — long term	82,987,000	84,639,000
Operating lease liability	2,155,000	2,514,000
Deferred revenue — long term	1,772,000	8,344,000
Milestone rights liability	5,926,000	7,263,000
Total liabilities	278,262,000	284,251,000
Commitments and contingencies
Stockholders' deficit:
Undesignated preferred stock, $0.01 par value — 10,000,000 shares authorized; no shares issued or outstanding as of March 31, 2020 and December 31, 2019
Common stock, $0.01 par value - 280,000,000 shares authorized, 213,137,684 and 211,787,573 shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively	2,131,000	2,118,000
Additional paid-in capital	2,801,044,000	2,799,278,000
Accumulated other comprehensive loss		(19,000)
Accumulated deficit	(3,001,225,000)	(2,991,903,000)
Total stockholders' deficit	(198,050,000)	(190,526,000)
Total liabilities and stockholders' deficit	$ 80,212,000	$ 93,725,000