Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 117,305	$ 135,797
Short-term investments	16,011	4,072
Receivable from collaboration partner		45,000
Prepaid expenses and other current assets	1,242	1,394
Total current assets	134,558	186,263
Property and equipment, net	2,856	2,758
Long-term investments	31,986	12,002
Other long-term assets	363	283
Total assets	169,763	201,306
Current liabilities
Accounts payable	1,362	1,798
Accrued liabilities	10,153	8,690
Deferred revenue - current	22,500	22,500
Total current liabilities	34,015	32,988
Other long-term liabilities	303	436
Deferred revenue - noncurrent	11,250	22,500
Total liabilities	45,568	55,924
Commitments and contingencies (Note 6)
Stockholders’ equity
Preferred stock, $0.0001 par value; 5,000,000 shares authorized; none issued and outstanding
Common stock, $0.0001 par value, 150,000,000 and 150,000,000 shares authorized at June 30, 2017 and December 31, 2016, respectively; 31,455,894 and 31,428,998 shares issued and outstanding at June 30, 2017 and December 31, 2016, respectively	3	3
Additional paid-in capital	226,471	223,208
Accumulated other comprehensive (loss) income	(50)	8
Accumulated deficit	(102,229)	(77,837)
Total stockholders’ equity	124,195	145,382
Total liabilities and stockholders’ equity	$ 169,763	$ 201,306