Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2015

Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table presents information about the Company’s assets and liabilities as of September 30, 2015 and December 31, 2014 that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values:

	Fair Value Measurements as of September 30, 2015 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash Equivalents	$	—	$	45,513	$	—	$	45,513
Investments:
Corporate Bonds	$	—	$	44,206	$	—	$	44,206
Commercial Paper		—		83,327		—		83,327
Government Securities		—		22,108		—		22,108
	$	—	$	195,154	$	—	$	195,154

	Fair Value Measurements as of December 31, 2014 Using:
	Level 1		Level 2		Level 3		Total
Liabilities:
Liability for preferred stock warrant	$	—	$	—	$	1,582	$	1,582
	$	—	$	—	$	1,582	$	1,582

Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss per Share

The following potential common shares, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect:

	Three and Nine Months Ended September 30,
	2015		2014
Stock options to purchase common stock		4,842,496		3,056,805
Unvested restricted common stock		625		78,125
Warrants for the purchase of convertible preferred stock		—		92,127
Warrants for the purchase of common stock		—		738,635
Convertible preferred stock (as converted to common stock)		—		15,309,548
		4,843,121		19,275,240