CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 23,419	$ 34,121
Contract and other receivables	674	1,141
Prepaid materials, net	3,923	3,924
Prepaid expenses and other current assets	573	1,221
Total current assets	28,589	40,407
Property and equipment, net	684	921
Intangibles, net	122	266
Other assets	387	487
Total assets	29,782	42,081
Current liabilities:
Accounts payable	1,024	1,321
Accrued liabilities	1,082	917
Accrued compensation	938	1,676
Current portion of term loan, less debt issuance costs	14,642	14,631
Current portion of contract liabilities	0	6
Other current liabilities	3,295	3,047
Total current liabilities	20,981	21,598
Other long-term liabilities	217	468
Total liabilities	21,198	22,066
Stockholders’ equity (deficit):
Common stock, $0.001 par value; 200,000,000 shares authorized, 35,922,916 and 21,018,663 shares issued and outstanding at June 30, 2020 (unaudited) and December 31, 2019, respectively	36	21
Additional paid-in capital	432,745	431,305
Accumulated deficit	(424,199)	(411,315)
Total stockholders’ equity	8,584	20,015
Total liabilities and stockholders’ equity	29,782	42,081
Class A-1 Convertible Preferred Stock
Stockholders’ equity (deficit):
Class A-1 convertible preferred stock, $0.001 par value; 415,898 shares authorized and issued at June 30, 2020 (unaudited) and December 31, 2019, respectively; 256,700 and 415,898 shares outstanding at June 30, 2020 (unaudited) and December 31, 2019, respectively	0	1
Class A-2 Convertible Preferred Stock
Stockholders’ equity (deficit):
Class A-1 convertible preferred stock, $0.001 par value; 415,898 shares authorized and issued at June 30, 2020 (unaudited) and December 31, 2019, respectively; 256,700 and 415,898 shares outstanding at June 30, 2020 (unaudited) and December 31, 2019, respectively	$ 2	$ 3