CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 57,057	$ 81,189
Australian tax incentive receivable	152	1,601
Short-term investments	210,852	167,218
Prepaid expenses and other current assets	3,758	2,688
Total current assets	271,819	252,696
Property and equipment, net	1,086	665
Long-term investments	32,730	75,897
Other long-term assets	322	46
Restricted cash	60	60
Total assets	306,017	329,364
Current liabilities:
Accounts payable	4,426	2,323
Accrued expenses	4,837	4,875
Notes payable, current portion	7,500	6,875
Other current liabilities	27	17
Total current liabilities	16,790	14,090
Notes payable, net of current portion	4,120	7,553
Deferred rent	128	140
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000 shares authorized and no shares, issued or outstanding at June 30, 2018 and December 31, 2017, respectively	0	0
Common stock, $0.001 par value, 500,000 shares authorized, 24,029 shares and 23,791 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	24	24
Additional paid in capital	399,370	393,017
Accumulated other comprehensive loss	(677)	(426)
Accumulated deficit	(113,738)	(85,034)
Total stockholders’ equity	284,979	307,581
Total liabilities, preferred stock and stockholders’ equity	$ 306,017	$ 329,364