Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
CURRENT ASSETS
Cash and cash equivalents	$ 85,645	$ 22,461
Marketable securities	38,070	52,052
Prepaid expenses and other current assets	3,103	2,158
Total current assets	126,818	76,671
Property and equipment, net	952	1,018
Other non-current assets	749	50
TOTAL ASSETS	128,519	77,739
CURRENT LIABILITIES
Accounts payable	3,223	663
Operating lease liabilities	317
Accrued and other current liabilities	8,266	9,576
Total current liabilities	11,806	10,239
Non-current operating lease liabilities	372
Other non-current liabilities	52	72
TOTAL LIABILITIES	12,230	10,311
Commitments and Contingencies (Note 6 and 10)
STOCKHOLDERS’ EQUITY
Preferred stock, $0.0001 par value; 10,000,000 shares authorized as of March 31, 2019 and December 31, 2018; no shares issued and outstanding as of March 31, 2019 and December 31, 2018
Common stock, $0.0001 par value; 500,000,000 shares authorized as of March 31, 2019 and December 31, 2018; 28,837,352 shares and 24,140,097 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	3	2
Additional paid-in capital	250,301	184,314
Accumulated other comprehensive income (loss)	13	(27)
Accumulated deficit	(134,028)	(116,861)
TOTAL STOCKHOLDERS’ EQUITY	116,289	67,428
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 128,519	$ 77,739