13.

WARRANTS

As more fully described in Note

10,

the Company completed a series of equity financing transactions in

2016

and

2015

that included the issuance of warrants to purchase

16,066,371

and

1,950,000

shares, respectively, of the Company’s common stock. In connection with the Hercules Credit Agreement entered into in

November

2013

as more fully described in Note

the Company issued warrants to purchase

194,986

shares of the Company’s common stock. We did

not

have any option or warrant exercises during

2015

through

2016

other than

250,000

shares during the

third

quarter of

2016

related to the Pre-funded Series B Warrants as discussed more fully in Note

10.

Following is a summary of all warrant activity for the

two

years ended

December

31,

2016:

Warrants	Number of Warrants Issued			Weighted Average Exercise Price
Warrants outstanding at January 1, 2015		5,069,815		$	8.18
Warrants issued in connection with the May 2015 equity transaction		1,950,000		$	2.60
Warrants expired during 2015		(1,125,140	)	$	7.98
Warrants outstanding at December 31, 2015		5,894,675		$	6.37
Warrants issued in connection with the 2016 equity transactions		16,066,371		$	0.92
Warrants exercised during 2016		(250,000	)	$	0.01
Warrants expired during 2016		(879,163	)	$	14.94
Warrants outstanding at December 31, 2016		20,831,883		$	1.88

Aggregate intrinsic value of outstanding warrants at December 31, 2016	$	534,000

Weighted average remaining contractual terms (years)		3.32	(1)

(1)

Does not include the remaining Pre-Funded Warrants issued in the

June

2016

Offering (totaling

1,850,000

shares underlying these warrants) as these warrants have no expiration date.