Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 13,485	$ 13,519
Short-term investments	19,371	46,555
Contract and other receivables	184	373
Prepaid materials, net	4,655	4,783
Prepaid expenses and other current assets	1,536	1,506
Total current assets	39,231	66,736
Property and equipment, net	8,906	9,708
Intangibles, net	705	775
Other assets	328	590
Total assets	49,170	77,809
Current liabilities:
Accounts payable	5,468	5,743
Accrued liabilities	2,090	2,995
Accrued compensation	1,223	1,985
Current portion of term loan, less debt issuance costs	19,888	19,859
Other current liabilities	2,130	2,018
Total current liabilities	30,799	32,600
Contract liabilities, less current portion	42	1,921
Deferred rent, less current portion	7,459	8,072
Other long-term liabilities	437	0
Total liabilities	38,737	42,593
Commitments and Contingencies
Stockholders’ equity:
Common stock, $0.001 par value; 200,000,000 shares authorized, 104,424,492 and 103,955,147 shares issued and outstanding at June 30, 2018 (unaudited) and December 31, 2017, respectively	104	104
Additional paid-in capital	384,296	381,104
Accumulated other comprehensive loss	(80)	(134)
Accumulated deficit	(373,887)	(345,858)
Total stockholders’ equity	10,433	35,216
Total liabilities and stockholders’ equity	$ 49,170	$ 77,809