Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 12,538	$ 14,941
Short-term investments	27,549	61,170
Contract and other receivables	690	1,657
Prepaid materials, net	6,149	5,552
Prepaid expenses and other current assets	3,018	4,154
Total current assets	49,944	87,474
Property and equipment, net	10,753	11,830
Intangibles, net	823	1,015
Other assets	340	342
Total assets	61,860	100,661
Current liabilities:
Accounts payable	4,901	5,840
Accrued liabilities	4,717	5,577
Accrued compensation	1,433	2,318
Current portion of deferred revenue	72	72
Total current liabilities	11,123	13,807
Term loan, less debt issuance costs	19,830	19,802
Deferred revenue, less current portion	1,957	1,993
Deferred rent, less current portion	8,672	8,840
Other long-term liabilities	283	144
Total liabilities	41,865	44,586
Commitments and Contingencies
Stockholders’ equity:
Common stock, $0.001 par value; 200,000,000 shares authorized, 53,182,330 and 52,924,805 shares issued and outstanding at June 30, 2017 (unaudited) and December 31, 2016, respectively	53	53
Additional paid-in capital	335,612	329,496
Accumulated other comprehensive loss	(88)	(123)
Accumulated deficit	(315,582)	(273,351)
Total stockholders’ equity	19,995	56,075
Total liabilities and stockholders’ equity	$ 61,860	$ 100,661