Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 53,187	$ 76,043
Available-for-sale-securities	400	7,481
Prepaid expenses and other current assets	4,316	2,778
Total current assets	57,903	86,302
Property and equipment, net	10,866	11,645
Operating lease, right-of-use assets	4,655	4,988
Other non-current assets	209	209
Restricted cash	327	327
Total assets	73,960	103,471
Current liabilities:
Accounts payable	2,383	7,124
Accrued expenses	8,507	9,178
Operating lease liabilities	1,799	1,736
Finance lease liabilities	191	186
Other current liabilities		52
Total current liabilities	12,880	18,276
Operating lease liabilities, excluding current portion	3,941	4,414
Finance lease liabilities, excluding current portion	683	733
Total liabilities	17,504	23,423
Commitments and contingencies (Note 11)
Preferred stock, $0.001 par value; 10,000,000 shares authorized at March 31, 2020 and December 31, 2019; no shares issued and outstanding at March 31, 2020 and December 31, 2019
Common stock, $0.001 par value; 300,000,000 shares authorized at March 31, 2020 and December 31, 2019; 46,070,724 shares issued and outstanding at March 31, 2020 and 45,987,571 shares issued and outstanding at December 31, 2019; 2,295,699 pre-funded warrants outstanding at March 31, 2020 and December 31, 2019	48	48
Additional paid-in capital	399,382	396,278
Accumulated other comprehensive (loss) gain	(1)	1
Accumulated deficit	(342,973)	(316,279)
Total stockholders’ equity	56,456	80,048
Total liabilities and stockholders’ equity	$ 73,960	$ 103,471

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).