Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 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 March 31,
	2019		2018
Common stock subject to repurchase	—			45,000
Warrants to purchase common stock		2,713,561		2,797,561
Common stock options		3,672,624		2,811,624
Employee stock purchase plan		6,126		6,902
Total excluded securities		6,392,311		5,661,087