Common Stock Reserved for Issuance

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Common Stock Reserved for Issuance

11. Common Stock Reserved for Issuance

The common stock reserved for future issuance at December 31, 2019 and 2018 was as follows:

	December 31,
	2019		2018
Shares underlying outstanding stock options		11,165,846		11,603,708
Shares available for future stock option grants		948,415		1,908,626
Shares issuable upon settlement of restricted    stock units outstanding		4,496,121		1,857,741
ESPP shares available for issuance		2,743,340		1,780,020
Warrants to purchase common stock		3,614,019		4,426,244
Total shares of common stock reserved		22,967,741		21,576,339