Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 43,567	$ 49,829
Marketable securities	110,121	221,148
Restricted cash	152
Accounts and other receivables	236	350
Prepaid expenses and other current assets	3,764	4,053
Total current assets	157,840	275,380
Marketable securities	75,274
Fixed assets, net	949	2,137
Operating lease right of use asset	2,265
Other assets	14	189
Restricted cash		152
Total assets	236,342	277,858
Current liabilities:
Accounts payable	3,144	2,335
Accrued expenses	13,710	9,363
Current portion of operating lease liability	754
Current portion of long-term debt		131
Total current liabilities	17,608	11,829
Long-term portion of operating lease liability	1,518
Other long-term liabilities		17
Total liabilities	19,126	11,846
Commitments and contingencies (Note 11)
Stockholders’ equity:
Common Stock, $0.001 par value; 300,000 and 200,000 shares authorized at September 30, 2019 and December 31, 2018, respectively; 139,891 and 138,716 shares issued and outstanding at September 30, 2019 and December 31, 2018, respectively	140	139
Additional paid-in capital	947,747	938,998
Accumulated deficit	(730,894)	(672,926)
Accumulated other comprehensive income (loss)	223	(199)
Total stockholders’ equity	217,216	266,012
Total liabilities and stockholders’ equity	$ 236,342	$ 277,858