Organization and Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2016

Accounting Policies [Abstract]

Schedule of Fair Value Measurements, Recurring and Nonrecurring Assets and Liabilities

The following table presents the Company’s fair value hierarchy for its warrant liabilities measured at fair value on a recurring basis (in thousands) as of March 31, 2016 and December 31, 2015:

	Quoted  Market  Prices for Identical Assets (Level 1)		Significant  Other Observable Inputs (Level 2)		Significant Unobservable Inputs  (Level 3)		Total
Warrant liabilities
Balance as of March 31, 2016	$	—	$	—	$	3,848	$	3,848
Balance as of December 31, 2015	$	—	$	—	$	1,841	$	1,841

Summary of Fair Value Measurements, Recurring and Nonrecurring, Valuation Assumptions

The following assumptions were used in determining the fair value of the common stock warrant liabilities valued using the Black-Scholes option pricing model for the three months ended March 31, 2016:

Risk-free interest rate	1.30		%
Volatility	95.26%-99.32%
Dividend yield	—		%
Expected term	6.79-6.93
Weighted average fair value	$	0.44

Summary of Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation

The following table is a reconciliation for all liabilities measured at fair value using Level 3 unobservable inputs (in thousands):

	Warrant liability
Balance as of December 31, 2015	$	1,841
Issuance of warrants in connection with January 2016 financing	4,807
Change in fair value measurement of warrant liability	(3,476		)
Repricing of February 2015 warrants in connection with January 2016 financing	676
Balance as of March 31, 2016	$	3,848

Schedule of Earnings Per Share, Basic and Diluted

he following table sets forth the computation of basic and diluted net loss per share for the three months ended March 31, 2016 and 2015 (in thousands, except per share data):

	2016			2015
Basic net loss per share
Net loss allocated to common stockholders	$	(2,505	)	$	(6,412	)
Weighted average common shares outstanding- basic	55,050			47,633
Net loss per share- basic	$	(0.05	)	$	(0.13	)
Diluted net loss per share
Net loss allocated to common stockholders- basic	$	(2,505	)	$	(6,412	)
Change in fair value of warrants	2,595			—
Net loss allocated to common stockholders	$	(5,100	)	$	(6,412	)
Weighted average common shares outstanding- basic	55,050			47,633
Dilutive securities	971			—
Weighted average common shares outstanding- diluted	56,021			47,633
Net loss per share- diluted	$	(0.09	)	$	(0.13	)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

The following securities that could potentially decrease net loss per share in the future are not included in the determination of diluted loss per share as they are anti-dilutive:

	Three Months Ended March 31,
	2016	2015
Outstanding stock options	5,528,168	4,592,562
Outstanding warrants	13,547,825	9,881,659
Restricted stock	224,677	—

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The following table presents the assumptions used by the Company to estimate the fair value of stock option grants using the Black-Scholes option-pricing model, as well as the resulting weighted average fair values:

	Three Months Ended   March 31,
	2016			2015
Risk-free interest rate	1.57%-1.78%			1.39% - 1.67%
Volatility	72.35%-80.02%			81.13%-101.54%
Dividend yield	—		%	—		%
Expected term	5.25-6.08 years			5.25- 6.08
Forfeiture rate	11.33		%	11.54		%
Weighted average fair value	$	0.76		$	1.05

Summary of Stock Option Activity

A summary of the Company’s stock option activity under all stock option plans during the three months ended March 31, 2016 is as follows (in thousands):

	Number of Shares		Weighted Average Exercise Price
Outstanding as of December 31, 2015	4,053,605		$	1.95
Granted	1,502,000		1.11
Exercised	—		—
Cancelled	(27,437	)	2.89
Outstanding as of March 31, 2016	5,528,168		$	1.71

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan

The following table summarizes the total stock-based compensation expense resulting from share-based awards recorded in the Company’s condensed consolidated statements of operations (in thousands):

	Three Months Ended   March 31,
	2016		2015
Research and development	$	64	$	30
General and administrative	291		259
Total	$	355	$	289