Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 51,740	$ 67,005
Restricted cash		158
Short-term investments	87,312
Accounts receivable, net	9,445	4,218
Inventory	7,482	4,973
Prepaid expenses and other current assets	3,227	3,122
Total current assets	159,206	79,476
Property and equipment, net	30,848	25,867
Long-term investments	42,059
Other assets	6,094	3,265
Total assets	238,207	108,608
Current liabilities:
Accounts payable	9,528	5,582
Accrued expenses and other current liabilities	20,829	19,707
PPP loan — current		4,061
Deferred revenue — current	14,016	33,275
Recognized loss on purchase commitments — current	5,660	11,080
Total current liabilities	50,033	73,705
Senior convertible notes	223,580
MidCap credit facility	38,723	49,335
Mann Group promissory notes	18,425	63,027
Accrued interest — Mann Group promissory notes	286	4,150
PPP loan — long term		812
2024 convertible notes		5,000
Recognized loss on purchase commitments — long term	79,653	84,208
Operating lease liability	798	1,202
Deferred revenue — long term	1,552	1,662
Milestone rights liability	4,838	5,926
Deposits from customer	5,007
Total liabilities	422,895	289,027
Commitments and contingencies (Note 12)
Stockholders' deficit:
Undesignated preferred stock, $0.01 par value — 10,000,000 shares authorized; no shares issued or outstanding as of September 30, 2021 and December 31, 2020
Common stock, $0.01 par value - 400,000,000 shares authorized, 250,245,831 and 242,117,089 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	2,502	2,421
Additional paid-in capital	2,914,818	2,866,303
Accumulated deficit	(3,102,008)	(3,049,143)
Total stockholders' deficit	(184,688)	(180,419)
Total liabilities and stockholders' deficit	$ 238,207	$ 108,608