CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 10,501	$ 3,084
Short-term investments	124,452	57,704
Receivables, net	3,841	35,185
Inventory	1,355	1,147
Prepaid expense and other assets	11,136	6,625
Total current assets	151,285	103,745
Property and equipment, net	2,551	3,829
Right of use assets	25,526	27,082
Restricted investments	1,055	1,154
Advanced payments, non-current	625	1,159
Total assets	181,042	136,969
Current liabilities:
Accounts payable	4,199	5,328
Accrued expenses	28,755	46,627
Current portion of lease liabilities	3,782	3,504
Total current liabilities	36,736	55,459
Lease liabilities, non-current	28,770	32,318
Unsecured convertible senior notes, net	236,288	158,213
Commitments and contingencies (Note 10)
Shareholders' deficit:
Preferred stock, par value $0.01 per share, 20,000,000 shares authorized; none issued and outstanding at December 31, 2020 and December 31, 2019.
Common stock, par value $0.01 per share, 150,000,000 shares authorized at December 31, 2020 and December 31, 2019; 61,671,231 and 54,200,810 shares issued and outstanding at December 31, 2020 and December 31, 2019, respectively.	616	542
Additional paid-in capital	751,304	625,048
Accumulated deficit	(872,672)	(734,611)
Total shareholders' deficit	(120,752)	(109,021)
Total liabilities and shareholders' deficit	$ 181,042	$ 136,969