Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 59,730	$ 89,893
Restricted cash	278	279
Accounts receivable	0	5,000
Prepaid expenses and other current assets	1,044	1,495
Total current assets	61,052	96,667
Property and equipment, net	1,301	1,222
Right-of-use asset, net	11,474	301
Long-term restricted cash	1,379	1,379
Total assets	75,206	99,569
Current liabilities:
Accounts payable	1,242	500
Accrued expenses	9,308	13,492
Loan payable	8,384	18,905
Lease liability	1,648	372
Deferred revenue	1,928	1,674
Total current liabilities	22,510	34,943
Non‑current liabilities:
Loan payable, net of current portion	6,449	0
Lease liability	10,120	0
Deferred revenue	16,412	14,680
Warrant liabilities	32,767	41,549
Total liabilities	88,258	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 June 30, 2020 and December 31, 2019, respectively	0	0
Common stock, $0.0001 par value; 200,000,000 shares authorized; 100,847,810 and 86,325,547 shares issued and outstanding as of June 30, 2020 and December 31, 2019, respectively	10	9
Additional paid-in capital	370,944	348,664
Accumulated deficit	(379,454)	(335,753)
Accumulated other comprehensive loss	(4,552)	(4,523)
Total stockholders’ equity (deficit)	(13,052)	8,397
Total liabilities and stockholders’ equity (deficit)	$ 75,206	$ 99,569