Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2015

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

The following table summarizes the assets and liabilities measured at fair value on a recurring basis (in thousands):



	March 31, 2015		Level 1		Level 2		Level 3
Assets
Cash and cash equivalents:
Cash	$	954	$	954	$	—	$	—
Money market funds	9,403		9,403		—		—
Corporate debt securities	3,950		—		3,950		—
Total cash and cash equivalents	14,307		10,357		3,950		—

Short-term investments:
Corporate debt securities	45,217		—		45,217		—
Commercial paper	8,499		—		8,499		—
Total short-term investments	53,716		—		53,716		—

Total	$	68,023	$	10,357	$	57,666	$	—



	December 31, 2014		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:



	Three Months Ended
	March 31,
	2015	2014
Common stock options	381,286	222,762
Common stock warrants	1,701,889	1,652,080
Total	2,083,175	1,874,842