CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 17,450	$ 16,034
Short-term investments	10,016	24,962
Grants receivable	901	1,232
Prepaid expenses	2,932	4,560
Other current assets	1,485	2,218
Total current assets	32,784	49,006
Property and equipment, net	308	345
Operating lease right-of-use assets	1,505	1,620
Other assets	63	63
Total assets	34,660	51,034
Current liabilities:
Accounts payable	1,150	1,304
Accrued expenses and other current liabilities	4,633	6,252
Total current liabilities	5,783	7,556
Operating lease liabilities, net of current portion	1,173	1,321
Total liabilities	6,956	8,877
Commitments (Notes 5 and 11)
Stockholders’ equity:
Common stock, par value $0.001; 125,000,000 shares authorized and 13,291,563 shares issued and outstanding as of March 31, 2020 and December 31, 2019	13	13
Additional paid-in capital	176,888	176,103
Accumulated other comprehensive income	28
Accumulated deficit	(149,225)	(133,959)
Total stockholders’ equity	27,704	42,157
Total liabilities and stockholders’ equity	$ 34,660	$ 51,034