CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 115,061	$ 56,461
Marketable securities		1,498
Prepaid expenses and other current assets	1,856	1,242
Total current assets	116,917	59,201
Property and equipment, net	1,856	2,181
Restricted cash	205	205
Other long‑term assets		50
Total assets	118,978	61,637
Current liabilities:
Accounts payable	2,598	1,359
Accrued expenses	3,356	2,796
Deferred rent		228
Loan payable	731	641
Total current liabilities	6,685	5,024
Long‑term portion of deferred rent	681	468
Long‑term portion of loan payable		398
Warrant to purchase redeemable security		37
Total liabilities	7,366	5,927
Commitments and contingencies (Note 9)
Convertible preferred stock (Series A-1, A-2, A-3, A-4, B and C), $0.001 par value; no shares authorized, issued or outstanding as of June 30, 2018; 43,157,651 shares authorized and 43,135,911 shares issued and outstanding as of December 31, 2017 (aggregate liquidation preference of $109,561 as of December 31, 2017)		109,232
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value; 10,000,000 and no shares authorized at June 30, 2018 and December 31, 2017, respectively; no shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively
Common stock, $0.001 par value; 150,000,000 shares authorized and 25,243,684 shares issued and outstanding as of June 30, 2018, respectively; 60,000,000 shares authorized and 3,970,586 shares issued and outstanding as of December 31, 2017, respectively	25	4
Additional paid-in capital	192,711	4,001
Accumulated other comprehensive loss		(2)
Accumulated deficit	(81,124)	(57,525)
Total stockholders’ equity (deficit)	111,612	(53,522)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 118,978	$ 61,637