Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 53,025	$ 13,899
Short-term investments	42,510	1,954
Prepaid expenses and other assets	2,415	656
Total current assets	97,950	16,509
Long-term investments	29,814
Property and equipment, net	1,793	1,925
Other assets	118	2,210
Total assets	129,675	20,644
Current liabilities:
Accounts payable	3,872	1,433
Accrued expenses	4,595	2,932
Current portion of deferred rent	315	295
Current portion of commercial bank debt	3,366	3,134
Convertible promissory note		2,000
Preferred stock warrant liabilities		319
Total current liabilities	12,148	10,113
Deferred rent, net of current portion	130	445
Commercial bank debt, net of current portion	1,776	5,142
Other long-term liabilities	$ 571	$ 335
Commitments and contingencies (Note 5)
Redeemable convertible preferred stock, $0.001 par value; authorized shares – 7,285,456 and 75,772,871 at December 31, 2015 and 2014, respectively; issued and outstanding shares – none and 73,487,415 at December 31, 2015 and 2014, respectively; liquidation preference of $0 and $95,619 at December 31, 2015 and 2014, respectively		$ 95,619
Stockholders’ equity (deficit):
Undesignated preferred stock, $0.001 par value; authorized shares – 5,000,000 at December 31, 2015 and none at December 31, 2014; issued and outstanding shares – none at December 31, 2015 and 2014
Common stock, $0.001 par value; authorized shares – 150,000,000 and 95,500,000 at December 31, 2015 and 2014, respectively; issued and outstanding shares – 23,670,079 and 909,880 at December 31, 2015 and 2014, respectively	$ 24	$ 1
Additional paid-in capital	273,321	19,209
Stockholder note receivable		(69)
Accumulated other comprehensive loss	(171)
Accumulated deficit	(158,124)	(110,151)
Total stockholders’ equity (deficit)	115,050	(91,010)
Total liabilities, redeemable convertible preferred stock and stockholders’ equity (deficit)	$ 129,675	$ 20,644