Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 31,530	$ 36,641
Marketable securities	137,522	137,777
Prepaid expenses and other current assets	2,738	4,368
Total Current Assets	171,790	178,786
Property, Plant and Equipment, Net	10,283	7,893
Deposits and other non-current assets	1,304	1,527
Marketable securities	1,100	1,360
Total Assets	184,477	189,566
Current liabilities:
Accounts Payable	1,020	550
Accrued expenses	11,497	6,488
Deferred revenue, current portion	3,380	6,764
Total current liabilities	15,897	13,802
Deferred rent, net of current portion	5,337	4,999
Deferred revenue, net of current portion	28,180	34,818
Other non-current liabilities	1,012	25
Total Liabilities	50,426	53,644
Stockholders’ equity:
Preferred stock, $0.001 par value: 5,000,000 shares authorized; no shares issued and outstanding at December 31, 2017 and 2016	0	0
Common stock, $0.001 par value: 120,000,000 shares authorized; 31,572,044 and 25,597,912 shares issued and outstanding at December 31, 2017 and 2016, respectively	32	26
Additional paid-in capital	295,019	225,963
Accumulated other comprehensive gain	(287)	(52)
Accumulated deficit	(160,713)	(90,015)
Total stockholders’ deficit	134,051	135,922
Total liabilities and stockholders’ equity	$ 184,477	$ 189,566