Stockholders' Equity (Tables)
|
12 Months Ended |
Dec. 31, 2015 |
|---|
| Schedule of share-based compensation expense recognized |
|
|
|
Year Ended December 31,
|
|
|
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|
2015
|
|
2014
|
|
|
Research and development
|
|
$
|
1,460,061
|
|
$
|
1,129,244
|
|
|
General and administrative
|
|
|
1,966,669
|
|
|
1,254,155
|
|
|
|
|
|
|
|
|
|
|
|
Total stock-based compensation
|
|
$
|
3,426,730
|
|
$
|
2,383,399
|
|
|
|
|
|
|
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| Summary of stock option activity |
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Options Outstanding
|
|
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Number
of Shares
|
|
Weighted-
Average
Exercise
Price
|
|
Weighted
Average
Remaining
Contractual
Term
(in years)
|
|
|
Balance, December 31, 2013
|
|
|
2,795,746
|
|
$
|
2.52
|
|
|
8.45
|
|
|
Granted
|
|
|
1,095,042
|
|
|
6.75
|
|
|
|
|
|
Exercised
|
|
|
(186,687
|
)
|
|
0.60
|
|
|
|
|
|
Forfeitures
|
|
|
(129,651
|
)
|
|
7.20
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Balance, December 31, 2014
|
|
|
3,574,450
|
|
$
|
3.75
|
|
|
8.06
|
|
|
Granted
|
|
|
1,645,960
|
|
|
7.16
|
|
|
|
|
|
Exercised
|
|
|
(384,033
|
)
|
|
2.36
|
|
|
|
|
|
Forfeitures
|
|
|
(206,304
|
)
|
|
6.04
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Balance, December 31, 2015
|
|
|
4,630,073
|
|
$
|
4.98
|
|
|
7.87
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Vested or expected to vest at December 31, 2015
|
|
|
4,488,894
|
|
$
|
4.91
|
|
|
|
|
|
|
|
|
|
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|
|
|
|
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|
Exercisable at December 31, 2015
|
|
|
1,941,347
|
|
$
|
3.10
|
|
|
|
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| Schedule of weighted-average assumptions: |
|
|
|
Year Ended
December 31,
2015
|
|
Year Ended
December 31,
2014
|
|
|
Expected term of options (in years)
|
|
|
6.2
|
|
|
5.8
|
|
|
Risk-free interest rate
|
|
|
1.7
|
%
|
|
1.8
|
%
|
|
Expected volatility
|
|
|
68.5
|
%
|
|
75.9
|
%
|
|
Dividend yield
|
|
|
0
|
%
|
|
0
|
%
|
|
| Schedule of shares of common stock reserved/available |
At December 31, 2015, the Company has reserved the following shares of common stock for issuance:
|
Stock options outstanding
|
|
|
4,630,073
|
|
|
Shares available for future grant under 2013 Plan
|
|
|
959,354
|
|
|
Employee stock purchase plan
|
|
|
225,806
|
|
|
Warrants outstanding
|
|
|
62,800
|
|
|
|
|
|
|
|
|
|
|
|
5,878,033
|
|
|
|
|
|
|
|
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|
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| 2013 plan |
|
| Schedule of shares of common stock reserved/available |
|
Available at December 31, 2014
|
|
|
829,364
|
|
|
Authorized
|
|
|
1,569,646
|
|
|
Granted
|
|
|
(1,645,960
|
)
|
|
Forfeitures/Expirations
|
|
|
206,304
|
|
|
|
|
|
|
|
|
Available at December 31, 2015
|
|
|
959,354
|
|
|
|
|
|
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