Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 72,606	$ 89,893
Restricted cash	279	279
Accounts receivable	0	5,000
Prepaid expenses and other current assets	1,555	1,495
Total current assets	74,440	96,667
Property and equipment, net	1,134	1,222
Right-of-use asset, net	11,847	301
Long-term restricted cash	1,379	1,379
Total assets	88,800	99,569
Current liabilities:
Accounts payable	1,330	500
Accrued expenses	8,775	13,492
Loan payable	16,868	18,905
Lease liability	1,425	372
Deferred revenue	1,674	1,674
Total current liabilities	30,072	34,943
Non‑current liabilities:
Lease liability	10,440	0
Deferred revenue	14,656	14,680
Warrant liabilities	42,395	41,549
Total liabilities	97,563	91,172
Commitments and contingencies (Note 17)
Stockholders’ equity (deficit):
Preferred stock, $0.0001 par value; 10,000,000 shares authorized; no shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively	0	0
Common stock, $0.0001 par value; 200,000,000 shares authorized; 87,019,172 and 86,325,547 shares issued and outstanding as of March 31, 2020 and December 31, 2019, respectively	9	9
Additional paid-in capital	351,184	348,664
Accumulated deficit	(355,373)	(335,753)
Accumulated other comprehensive loss	(4,583)	(4,523)
Total stockholders’ equity (deficit)	(8,763)	8,397
Total liabilities and stockholders’ equity (deficit)	$ 88,800	$ 99,569