CONDENSED BALANCE SHEETS (unaudited) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 24,341,000	$ 13,406,000
Other receivable	411,000
Prepaid expenses and other assets	216,000	340,000
Total current assets	24,968,000	13,746,000
Property and equipment, net	251,000	302,000
Deferred offering costs	2,218,000
Other assets	51,000	51,000
Total assets	27,488,000	14,099,000
Current liabilities:
Convertible promissory notes, net of discount		12,095,000
Derivative liability		3,028,000
Current portion of long-term debt	3,125,000	761,000
Accounts payable	1,576,000	430,000
Accrued expenses	2,987,000	1,281,000
Total current liabilities	7,688,000	17,595,000
Preferred stock warrant liability	5,990,000	1,656,000
Deferred rent		5,000
Long-term debt	4,375,000	2,625,000
Total liabilities	18,053,000	21,881,000
Commitments and contingencies (Note 7)
Redeemable convertible preferred stock, $0.001 par value; 18,292,696 and 13,321,350 shares authorized at September 30, 2018 and December 31, 2017, respectively; 13,200,115 and 9,131,999 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively; liquidation preference of $129,071,361 and $89,776,055 at September 30, 2018 and December 31, 2017, respectively	125,609,295	89,633,543
Stockholders’ deficit:
Common stock, $0.001 par value; 20,789,273 shares authorized; 795,640 shares issued and 765,673 shares outstanding at September 30, 2018; 775,755 shares issued and 745,788 shares outstanding at December 31, 2017	1,000	1,000
Treasury stock, at cost, 29,967 shares as of September 30, 2018 and December 31, 2017	(24,000)	(24,000)
Additional paid-in capital	1,892,000	1,672,000
Accumulated deficit	(118,043,000)	(99,065,000)
Total stockholders’ deficit	(116,174,000)	(97,416,000)
Total liabilities, redeemable convertible preferred stock, and stockholders' deficit	$ 27,488,000	$ 14,099,000