Condensed Consolidated Balance Sheets (Unaudited) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 30,607,868	$ 50,234,871
Marketable securities	48,556,558	37,762,439
Restricted cash	100,000	100,000
Prepaid expenses and other current assets	1,054,034	1,921,050
Total current assets	80,318,460	90,018,360
Equipment, net	29,111	33,478
Other noncurrent assets	14,808	14,808
Operating lease right-of-use assets	371,370
In-process research and development	34,200,000	34,200,000
Goodwill	14,869,399	14,869,399
Total assets	129,803,148	139,136,045
Current liabilities
Accounts payable	3,025,563	1,799,666
Accrued expenses and other current liabilities	3,720,955	1,809,532
Operating leases	156,159
Total current liabilities	6,902,677	3,609,198
Deferred taxes	4,057,488	4,057,488
Deferred revenue	41,175,600	41,175,600
Noncurrent operating leases	243,115
Other noncurrent liabilities		28,990
Total liabilities	52,378,880	48,871,276
Commitments and contingencies
Stockholders’ equity
Preferred stock; $0.0001 par value; 100,000,000 shares authorized; none issued or outstanding as of March 31, 2019 and December 31, 2018, respectively
Common stock; $0.0001 par value; 125,000,000 shares authorized; 39,025,471 and 38,937,971 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	3,903	3,894
Additional paid-in capital	307,800,293	304,813,603
Accumulated deficit	(230,379,928)	(214,552,728)
Total stockholders’ equity	77,424,268	90,264,769
Total liabilities and stockholders’ equity	$ 129,803,148	$ 139,136,045