SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of estimated useful lives of assets

Depreciation of property and equipment is calculated using the straight-line method over the estimated useful lives of the assets, as follows:



Computer equipment		3 years
Office and other equipment		6 years
Laboratory equipment		6 years
Leasehold improvements		The lesser of the lease term or the life of the asset

Schedule of assets and liabilities that are measured at fair value on a recurring basis



	December 31, 2015
	Total		Level 1		Level 2		Level 3
Assets
Cash and cash equivalents:
Cash	$	757	$	757	$	—	$	—
Money market funds	18,875		18,875		—		—
Corporate debt securities	6,749		—		6,749		—
Commercial paper	22,994				22,994
Total cash and cash equivalents	49,375		19,632		29,743		—

Short-term investments:
Corporate debt securities	27,622		—		27,622		—
Commercial paper	45,212		—		45,212		—
Total short-term investments	72,834		—		72,834		—

Total	$	122,209	$	19,632	$	102,577	$	—



	December 31, 2014
	Total		Level 1		Level 2		Level 3
Assets
Cash and cash equivalents:
Cash	$	1,025	$	1,025	$	—	$	—
Money market funds	3,565		3,565		—		—
Corporate debt securities	2,003		—		2,003		—
Total cash and cash equivalents	6,593		4,590		2,003		—

Short-term investments:
Corporate debt securities	21,210		—		21,210		—
Commercial paper	1,500		—		1,500		—
Total short-term investments	22,710		—		22,710		—

Total	$	29,303	$	4,590	$	24,713	$	—

Schedule of potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive

The following table presents the weighted average number of potentially dilutive securities not included in the calculation of diluted net loss per share due to the anti-dilutive effect of the securities:



	Year ended
	December 31,
	2015	2014	2013
Common stock options	582,662	253,595	495
Common stock warrants	1,546,201	1,515,445	644,426
Total	2,128,863	1,769,040	644,921