Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 74,991	$ 53,241
Short-term investments	71,975	115,602
Prepaid expenses and other current assets	5,393	4,854
Total current assets	152,359	173,697
Property and equipment, net	9,755	10,672
Long-term investments	1,608	1,601
Operating lease right-of-use asset	16,946	17,615
Other non-current assets	2,282	2,297
Total assets	182,950	205,882
Current liabilities:
Accounts payable	3,722	2,460
Accrued expenses	7,543	8,907
Operating lease liability, current	2,991	2,901
Other current liabilities	39	132
Total current liabilities	14,295	14,400
Operating lease liability, net of current portion	16,111	16,889
Total liabilities	30,406	31,289
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value: 5,000 shares authorized at March 31, 2020 and December 31, 2019; no shares issued or outstanding at March 31, 2020 or December 31, 2019	0	0
Common stock, $0.001 par value: 160,000 shares authorized at March 31, 2020 and December 31, 2019; 34,049 and 33,738 shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively	34	34
Additional paid-in capital	285,968	281,664
Accumulated other comprehensive income	144	54
Accumulated deficit	(133,602)	(107,159)
Total stockholders’ equity	152,544	174,593
Total liabilities and stockholders’ equity	$ 182,950	$ 205,882