Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2019

Accounting Policies [Abstract]

Summary of Outstanding Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share

For the periods presented, the following table sets forth the outstanding potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because their inclusion would be anti-dilutive:

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Common stock subject to repurchase	—			30,165	—			37,582
Warrants to purchase common stock		2,713,561		2,797,561		2,713,561		2,797,561
Common stock options		3,232,871		3,017,624		3,232,871		3,017,624
Employee stock purchase plan	—			19,144	—			26,047
Total excluded securities		5,946,432		5,864,494		5,946,432		5,878,814