CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 28,052	$ 34,121
Contract and other receivables	676	1,141
Prepaid materials, net	3,924	3,924
Prepaid expenses and other current assets	955	1,221
Total current assets	33,607	40,407
Property and equipment, net	801	921
Intangibles, net	159	266
Other assets	439	487
Total assets	35,006	42,081
Current liabilities:
Accounts payable	1,030	1,321
Accrued liabilities	860	917
Accrued compensation	532	1,676
Current portion of term loan, less debt issuance costs	14,636	14,631
Current portion of contract liabilities	0	6
Other current liabilities	2,728	3,047
Total current liabilities	19,786	21,598
Other long-term liabilities	318	468
Total liabilities	20,104	22,066
Stockholders’ equity (deficit):
Common stock, $0.001 par value; 200,000,000 shares authorized, 27,608,783 and 21,018,663 shares issued and outstanding at March 31, 2020 (unaudited) and December 31, 2019, respectively	22	21
Additional paid-in capital	432,129	431,305
Accumulated deficit	(417,252)	(411,315)
Total stockholders’ equity	14,902	20,015
Total liabilities and stockholders’ equity	35,006	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, issued and outstanding at March 31, 2020 (unaudited) and December 31, 2019, respectively	1	1
Class A-2 Convertible Preferred Stock
Stockholders’ equity (deficit):
Class A-1 convertible preferred stock, $0.001 par value; 415,898 shares authorized, issued and outstanding at March 31, 2020 (unaudited) and December 31, 2019, respectively	$ 2	$ 3