Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

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

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

	Year Ended December 31,
	2017	2016
Common stock subject to repurchase	45,000		45,000
Warrants to purchase common stock	2,744,500		3,323,876
Common stock options	2,131,624		1,275,624
Employee stock purchase plan	27,785		43,752
Total excluded securities	4,948,909		4,688,252