Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 30,347	$ 22,493
Marketable securities	6,769	33,783
Restricted cash	52	43
Prepaid expenses and other current assets	1,800	1,390
Total current assets	38,968	57,709
Property and equipment, net	165	201
Operating lease right-of-use asset	678	924
Other long-term assets	110	113
Total assets	39,921	58,947
Current liabilities:
Accounts payable	770	1,871
Accrued expenses	3,485	4,655
Current portion of long-term debt	5,149	4,336
Advances from collaboration partners	805	403
Current portion of operating lease liability	524	499
Taxes payable	38	43
Total current liabilities	10,771	11,807
Long-term debt	8,704	10,502
Operating lease liability	155	425
Total liabilities	19,630	22,734
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value per share, 5,000,000 shares authorized, no shares issued or outstanding as of June 30, 2020 and December 31, 2019
Common stock, $0.01 par value per share, 500,000,000 shares authorized, 40,326,906 and 40,186,469 shares issued, and 40,135,290 and 40,030,763 shares outstanding as of June 30, 2020 and December 31, 2019, respectively	403	402
Common stock in treasury, at cost, 191,616 and 155,706 shares as of June 30, 2020 and December 31, 2019, respectively	(1,822)	(1,703)
Additional paid-in capital	180,549	174,515
Accumulated other comprehensive income	13	18
Accumulated deficit	(158,852)	(137,019)
Total stockholders’ equity	20,291	36,213
Total liabilities and stockholders’ equity	$ 39,921	$ 58,947