Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2019

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 Months Ended March 31,
	2019		2018
Stock options to purchase common stock		8,908,432		7,498,791
Unvested restricted stock units		150,400		302,665
Shares issuable under ESPP		6,911		—
		9,065,743		7,801,456

Summary of Impact on Condensed Consolidated Balance Sheets for Opening Balances Related to Lease

The impact to the Condensed Consolidated Balance Sheets for the opening balances is as follows (in thousands):

	As Previously Reported December 31, 2018		Adoption Adjustment			As reported under Topic 842 January 1, 2019
Operating lease assets	$	—	$	13,737		$	13,737
Accrued expenses and other current liabilities		15,207		(1,768	)		13,439
Operating lease liabilities		—		4,285			4,285
Lease incentive obligation, net of current portion		6,776		(6,776	)		—
Deferred rent		2,216		(2,216	)		—
Operating lease liabilities, net of current portion		—		20,212			20,212