Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 10,206	$ 4,027
Short‑term investments	49,295	26,881
Accounts receivable	786	0
Prepaid expenses and other current assets	3,574	632
Total current assets	63,861	31,540
Long‑term investments	2,978	10,420
Property and equipment, net	28	27
Prepaid and other long‑term assets	0	66
Total assets	66,867	42,053
Current liabilities:
Accounts payable	2,462	1,526
Accrued expenses and other current liabilities	3,559	581
Deferred revenue, current	1,796	1,796
Total current liabilities	7,817	3,903
Deferred revenue, long‑term	6,735	8,531
Other non‑current liabilities	22	57
Total liabilities	14,574	12,491
Commitments and contingencies (see Note 5)
Stockholders’ deficit:
Common stock, $0.0001 par value, 55,000,000 and 36,500,000 shares authorized at December 31, 2017 and 2016, respectively; 5,298,593 and 5,280,058 shares issued and outstanding at December 31, 2017 and 2016, respectively	1	1
Additional paid‑in capital	2,207	699
Accumulated other comprehensive loss	(51)	(26)
Accumulated deficit	(59,191)	(30,115)
Total stockholders’ deficit	(57,034)	(29,441)
Total liabilities, convertible preferred stock and stockholders’ deficit	66,867	42,053
Series A Convertible Preferred Stock
Current liabilities:
Convertible preferred stock	14,183	14,183
Series B Convertible Preferred Stock
Current liabilities:
Convertible preferred stock	44,820	44,820
Series C Convertible Preferred Stock
Current liabilities:
Convertible preferred stock	$ 50,324	$ 0