BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 88,419	$ 61,729
Receivables	3,441	1,864
Prepaid expenses and other current assets	23,739	20,692
Total current assets	115,599	84,285
Property and equipment, net	828	1,097
Operating lease right of use assets	1,283
Deposits	130	128
Other non-current assets	109	9,541
Total assets	117,949	95,051
Current liabilities:
Accounts payable	926	707
Accrued expenses	9,573	8,763
Lease liability—current portion	677
Deferred rent—current portion		13
Total current liabilities	11,176	9,483
Lease liability—noncurrent portion	647
Deferred rent—noncurrent portion		4
Total liabilities	11,823	9,487
Commitments and contingencies (Note 7)
Stockholders' equity:
Common stock, $0.001 par value; 250,000,000 shares authorized; 181,030,020 and 161,066,136 shares issued and outstanding at September 30, 2019 and December 31, 2018, respectively	181	161
Additional paid-in capital	774,324	651,732
Accumulated deficit	(668,379)	(566,329)
Total stockholders' equity	106,126	85,564
Total liabilities and stockholders' equity	$ 117,949	$ 95,051