Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 113,114	$ 126,310
Short-term marketable securities	153,794	140,129
Accounts receivable	707	12,037
Prepaid expenses and other current assets	4,839	4,500
Total current assets	272,454	282,976
Long-term marketable securities		11,434
Property and equipment, net	28,169	29,157
Operating lease right-of-use assets	21,828
Goodwill	8,168	8,334
Intangible assets, net	24,499	25,135
Restricted cash	468	468
Total assets	355,586	357,504
Current liabilities:
Accounts payable	1,573	1,457
Accrued clinical trial and manufacturing expenses	2,742	2,542
Accrued expenses and other liabilities	8,049	10,518
Operating lease liabilities	1,539
Deferred revenue	16,000	16,000
Total current liabilities	29,903	30,517
Deferred rent		11,063
Contingent consideration	978	998
Deferred revenue	169,497	172,671
Deferred tax liabilities	5,948	6,104
Operating lease liabilities	33,030
Other long-term liabilities	841	840
Total liabilities	240,197	222,193
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized; and no shares issued and outstanding at March 31, 2019 and December 31, 2018
Common stock, $0.0001 par value; 300,000,000 shares authorized; and 79,852,045 and 79,571,714 shares issued and outstanding at March 31, 2019 and December 31, 2018	8	8
Additional paid-in capital	542,849	538,895
Accumulated other comprehensive income	491	940
Accumulated deficit	(427,959)	(404,532)
Total stockholders’ equity	115,389	135,311
Total liabilities and stockholders’ equity	$ 355,586	$ 357,504