Unaudited Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 19,908	$ 35,656
Short-term investments	34,991	22,930
Prepaid expenses and other current assets	691	741
Total current assets	55,590	59,327
Other assets	730	120
Deferred offering costs	335	345
Total assets	56,655	59,792
Current liabilities:
Accounts payable	2,044	2,192
Accrued expenses	1,057	1,268
Deferred revenue, current portion	257	257
Total current liabilities	3,358	3,717
Deferred revenue, non-current	314	378
Deferred rent	20	25
Warrant liability	5,078	6,601
Loan payable, long term	14,352	14,252
Total liabilities	23,122	24,973
Commitments and contingencies
Stockholders’ equity:
Preferred stock	0	0
Common stock	25	24
Additional paid-in capital	218,567	214,918
Accumulated deficit	(185,059)	(180,123)
Total stockholders’ equity	33,533	34,819
Total liabilities and stockholders’ equity	$ 56,655	$ 59,792

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).

Name:	us-gaap_AccountsPayableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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).