STOCKHOLDERS' EQUITY (DEFICIT) (Tables)

3 Months Ended

Mar. 31, 2020

Equity [Abstract]

Summary of Common Stock

In addition, the Company had reserved for issuance the following amounts of shares of its common stock for the purposes described below as of March 31, 2020 and December 31, 2019 (in thousands):

	March 31, 2020	December 31, 2019
Shares of common stock issued	109,992	106,801
Shares of common stock reserved for issuance for:
Warrants	22,895	22,895
Stock options	9,704	6,236
Shares available for grant under 2014 Stock Incentive Plan	5,370	8,753
Shares available for sale under 2014 Employee Stock Purchase Plan	25	28
Total shares of common stock issued and reserved for issuance	147,986	144,713

Summary of Warrants Outstanding and Warrant Activity

The following table sets forth the Company's warrant activity for the three months ended March 31, 2020 (in thousands):

			Year-to-Date Warrant Activity
Issued	Exercise Price (1)	Expiration	December 31, 2019	Issued	(Exercised)	March 31, 2020
Jun-2019	$1.47	Jun-2020	20,410	—	—	20,410
Mar-2018	$0.95*	Mar-2023	1,943	—	—	1,943
Nov-2017	$0.55*	Nov-2022	487	—	—	487
May-2015	$11.83	Nov-2024	28	—	—	28
Nov-2014	$11.04	Nov-2024	27	—	—	27
			22,895	—	—	22,895

⁽¹⁾ As of March 31, 2020.

* Exercise price shown subject to further adjustment based on down round provision added by amendment.