Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 53,241	$ 47,906
Short-term investments	115,602	141,968
Prepaid expenses and other current assets	4,854	2,335
Total current assets	173,697	192,209
Property and equipment, net	10,672	13,540
Long-term investments	1,601	5,990
Operating lease right-of-use asset	17,615
Other non-current assets	2,297	2,713
Total assets	205,882	214,452
Current liabilities:
Accounts payable	2,460	3,272
Accrued expenses	8,907	6,952
Deferred revenue, current—related party	0	55,157
Operating lease liability, current	2,901
Other current liabilities	132	165
Total current liabilities	14,400	65,546
Deferred revenue, net of current portion—related party	0	42,715
Operating lease liability, net of current portion	16,889
Other non-current liabilities	0	2,062
Total liabilities	31,289	110,323
Commitments and contingencies (Note 13)
Stockholders’ equity:
Preferred stock, $0.001 par value: 5,000 shares authorized at December 31, 2019 and 2018; no shares issued or outstanding at December 31, 2019 or 2018	0	0
Common stock, $0.001 par value: 160,000 shares authorized at December 31, 2019 and 2018; 33,738 and 32,948 shares issued at December 31, 2019 and 2018, respectively; 33,738 and 32,941 shares outstanding at December 31, 2019 and 2018, respectively	34	33
Additional paid-in capital	281,664	268,081
Accumulated other comprehensive income (loss)	54	(78)
Accumulated deficit	(107,159)	(163,907)
Total stockholders’ equity	174,593	104,129
Total liabilities and stockholders’ equity	$ 205,882	$ 214,452