Common Stock (Tables)
|
12 Months Ended |
Dec. 31, 2018 |
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| Equity [Abstract] |
|
| Summary of Fair Value of Option Awards |
The estimated fair value of stock options granted in the respective periods was determined using the Black-Scholes option pricing model using the following weighted average assumptions:
|
|
|
2018
|
|
|
2017
|
|
|
|
Risk-free interest rates
|
|
|
2.93
|
%
|
|
|
1.95
|
%
|
|
|
Expected dividend yield
|
|
|
0
|
%
|
|
|
0
|
%
|
|
|
Expected life
|
|
5.68 years
|
|
|
6.02 years
|
|
|
|
Expected volatility
|
|
|
88.23
|
%
|
|
|
86.06
|
%
|
|
|
| Summary of Share-Based Compensation Expense |
The results for the periods set forth below included stock-based compensation expense in the following expense categories of the consolidated statements of loss (in thousands):
|
|
|
Year ended
|
|
|
|
|
December 31,
|
|
|
|
|
2018
|
|
|
2017
|
|
|
Research and development
|
|
$
|
272
|
|
|
$
|
107
|
|
|
General and administrative
|
|
|
582
|
|
|
|
241
|
|
|
Total stock-based compensation
|
|
$
|
854
|
|
|
$
|
348
|
|
|
| Summary of Stock Options Activity |
Stock option transactions and the number of stock options outstanding are summarized below:
|
|
|
Number of
|
|
|
Weighted
|
|
|
|
|
Optioned
|
|
|
Average
|
|
|
|
|
Common
|
|
|
Exercise
|
|
|
|
|
Shares
|
|
|
Price
|
|
|
Balance, January 1, 2018
|
|
|
111,578
|
|
|
$
|
80.01
|
|
|
Granted
|
|
|
554,400
|
|
|
|
2.81
|
|
|
Forfeited
|
|
|
(393
|
)
|
|
|
160.79
|
|
|
Balance, December 31, 2018
|
|
|
665,585
|
|
|
$
|
15.65
|
|
|
| Summary of Stock Options Outstanding Regarding Number of Common Shares Issuable upon Exercise of Outstanding Options |
(1) Number of common shares issuable upon exercise of outstanding options:
|
|
|
|
|
|
|
|
|
|
|
Weighted-
|
|
|
|
|
|
|
|
|
|
|
|
|
Average
|
|
|
|
|
|
|
|
|
|
|
|
|
Remaining
|
|
|
|
|
|
|
|
|
Weighted-
|
|
|
Contractual
|
|
|
|
|
|
|
|
|
Average
|
|
|
Life
|
|
|
Exercise Prices
|
|
Number of Options
|
|
|
Exercise Price
|
|
|
(in years)
|
|
|
$2.56 - $2.97
|
|
|
386,650
|
|
|
$
|
2.56
|
|
|
|
9.72
|
|
|
$2.98 - $16.13
|
|
|
167,750
|
|
|
|
3.37
|
|
|
|
9.57
|
|
|
$16.14 - $69.45
|
|
|
104,910
|
|
|
|
28.90
|
|
|
|
8.58
|
|
|
$69.46 - $157.30
|
|
|
408
|
|
|
|
110.00
|
|
|
|
7.40
|
|
|
$157.31 - $206.25
|
|
|
1,782
|
|
|
|
204.60
|
|
|
|
6.38
|
|
|
$206.26 - $1,228.15
|
|
|
835
|
|
|
|
448.47
|
|
|
|
5.53
|
|
|
$1,228.16 - $1,305.70
|
|
|
907
|
|
|
|
1,296.49
|
|
|
|
5.15
|
|
|
$1,305.71 - $1,405.80
|
|
|
713
|
|
|
|
1,321.28
|
|
|
|
4.12
|
|
|
$1,405.81 - $1,659.35
|
|
|
605
|
|
|
|
1,443.12
|
|
|
|
3.21
|
|
|
$1,659.36 - $2,450.80
|
|
|
1,025
|
|
|
|
2,007.37
|
|
|
|
1.65
|
|
|
|
|
|
665,585
|
|
|
$
|
15.65
|
|
|
|
9.46
|
|
|
| Summary of Stock Options Outstanding Regarding Number of Common Shares Issuable upon Exercise of Vested Options |
(2) Number common shares issuable upon exercise of vested options:
|
|
|
|
|
|
|
|
|
|
|
Weighted-
|
|
|
|
|
|
|
|
|
|
|
|
|
Average
|
|
|
|
|
|
|
|
|
|
|
|
|
Remaining
|
|
|
|
|
|
|
|
|
Weighted-
|
|
|
Contractual
|
|
|
|
|
|
|
|
|
Average
|
|
|
Life
|
|
|
Exercise Prices
|
|
Number of Options
|
|
|
Exercise Price
|
|
|
(in years)
|
|
|
$2.56 - $2.97
|
|
|
35,417
|
|
|
$
|
2.56
|
|
|
|
9.72
|
|
|
$2.98 - $16.13
|
|
|
17,472
|
|
|
|
3.37
|
|
|
|
9.57
|
|
|
$16.14 - $69.45
|
|
|
37,488
|
|
|
|
28.90
|
|
|
|
8.58
|
|
|
$69.46 - $157.30
|
|
|
408
|
|
|
|
110.00
|
|
|
|
7.40
|
|
|
$157.31 - $206.25
|
|
|
1,745
|
|
|
|
204.60
|
|
|
|
6.38
|
|
|
$206.26 - $1,228.15
|
|
|
835
|
|
|
|
448.47
|
|
|
|
5.53
|
|
|
$1,228.16 - $1,305.70
|
|
|
907
|
|
|
|
1,296.49
|
|
|
|
5.15
|
|
|
$1,305.71 - $1,405.80
|
|
|
713
|
|
|
|
1,321.28
|
|
|
|
4.12
|
|
|
$1,405.81 - $1,659.35
|
|
|
605
|
|
|
|
1,443.12
|
|
|
|
3.21
|
|
|
$1,659.36 - $2,450.80
|
|
|
1,025
|
|
|
|
2,007.37
|
|
|
|
1.65
|
|
|
|
|
|
96,615
|
|
|
$
|
73.05
|
|
|
|
8.94
|
|
|
| Summary of Restricted Stock Unit Award Activity |
The following table summarizes our restricted stock unit award activity during the year ended December 31, 2018:
|
|
|
|
|
|
|
Weighted
|
|
|
|
|
Number
|
|
|
Average
|
|
|
|
|
of
|
|
|
Grant Date
|
|
|
|
|
Shares
|
|
|
Fair Value
|
|
|
Balance, January 1, 2018
|
|
|
21,066
|
|
|
$
|
38.87
|
|
|
Released
|
|
|
(5,354
|
)
|
|
|
56.25
|
|
|
Forfeited or expired
|
|
|
(570
|
)
|
|
|
97.03
|
|
|
Balance, December 31, 2018
|
|
|
15,142
|
|
|
$
|
30.53
|
|
|
| Summary of Outstanding Warrants |
The following is a summary of outstanding warrants to purchase common stock at December 31, 2018:
|
|
|
Total
|
|
|
|
|
|
|
|
|
|
|
Outstanding
|
|
|
Exercise
|
|
|
|
|
|
|
and
|
|
|
price per
|
|
|
|
|
|
|
Exercisable
|
|
|
Share
|
|
|
Expiration Date
|
|
(1) Series A Warrants issued in July 2014 financing
|
|
|
25,272
|
|
|
$
|
440.00
|
|
|
July 2019
|
|
(2) Series B Warrants issued in July 2014 financing
|
|
|
6,093
|
|
|
$
|
440.00
|
|
|
July 2019
|
|
(3) Series A-1 Warrants issued in April 2015 financing
|
|
|
2,175
|
|
|
$
|
264.00
|
|
|
October 2020
|
|
(4) Warrants issued in September 2017 financing
|
|
|
8,224
|
|
|
$
|
34.96
|
|
|
March 2023
|
|
(5) Warrants issued in June 2018 financing
|
|
|
3,119,500
|
|
|
$
|
4.00
|
|
|
June 2023
|
|
(6) Warrants issued in October 2018 financing
|
|
|
894,626
|
|
|
$
|
3.14
|
|
|
October 2023
|
|
| Summary of Fair Value of Warrants Issued |
|
|
|
As of
|
|
|
|
|
December 31,
|
|
|
Series A and Series B Warrant Valuation Assumptions
|
|
2018
|
|
|
2017
|
|
|
Risk-free interest rates
|
|
|
2.61
|
%
|
|
|
1.82
|
%
|
|
Expected dividend yield
|
|
|
0
|
%
|
|
|
0
|
%
|
|
Expected life
|
|
0.50 years
|
|
|
1.50 years
|
|
|
Expected volatility
|
|
|
111
|
%
|
|
|
86
|
%
|
|
| Computation of Basic and Diluted Net Loss Attributable to Common Shareholders Per Share |
The following table presents the computation of basic and diluted net loss attributable to common stockholders per share (in thousands, except per share and share amounts):
|
|
|
Years ended December 31,
|
|
|
|
|
2018
|
|
|
2017
|
|
|
2016
|
|
|
Numerator
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Net loss
|
|
$
|
(12,687
|
)
|
|
$
|
(10,583
|
)
|
|
$
|
(1,234
|
)
|
|
Denominator
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Weighted average number of common shares outstanding
|
|
|
3,510,217
|
|
|
|
479,442
|
|
|
|
2,123
|
|
|
Basic and diluted net loss per common share
|
|
$
|
(3.61
|
)
|
|
$
|
(22.07
|
)
|
|
$
|
(581.25
|
)
|
|