Stock-Based Compensation (Tables)
|
12 Months Ended |
Dec. 31, 2015 |
|---|
| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
|
| Summary of Stock Option Activity Under the 2012 and 2013 Plans |
Stock option activity under the 2012 and 2013 plans is summarized
as follows:
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
Number
of Options |
|
|
Weighted-
Average
Exercise
Price |
|
|
Weighted-
Average
Remaining
Contractual
Term
(in years) |
|
|
Aggregate
Intrinsic
Value
(in thousands) |
|
|
Outstanding at December 31, 2014
|
|
|
537,683 |
|
|
$ |
6.19 |
|
|
|
8.9 |
|
|
$ |
2,488 |
|
|
Granted
|
|
|
914,722 |
|
|
|
7.74 |
|
|
|
|
|
|
|
|
|
|
Exercised
|
|
|
(53,458 |
) |
|
|
0.76 |
|
|
|
|
|
|
|
|
|
|
Cancelled
|
|
|
(176,180 |
) |
|
|
8.13 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Outstanding at December 31, 2015
|
|
|
1,222,767 |
|
|
$ |
7.31 |
|
|
|
9.0 |
|
|
$ |
(4,679 |
) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Vested and expected to vest at December 31, 2014
|
|
|
451,153 |
|
|
$ |
5.83 |
|
|
|
8.9 |
|
|
$ |
2,247 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Vested and expected to vest at December 31, 2015
|
|
|
1,133,925 |
|
|
$ |
7.29 |
|
|
|
9.0 |
|
|
$ |
(4,293 |
) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Exercisable at December 31, 2014
|
|
|
139,798 |
|
|
$ |
1.84 |
|
|
|
8.1 |
|
|
$ |
1,239 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Exercisable at December 31, 2015
|
|
|
318,733 |
|
|
$ |
4.60 |
|
|
|
7.6 |
|
|
$ |
(351 |
) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Additional Information about Stock Option Activity |
Additional information about the Company’s stock option
activity is as follows:
|
|
|
|
|
|
|
|
|
| |
|
Years Ended December 31, |
|
| |
|
2015 |
|
|
2014 |
|
|
Weighted-average grant date fair value per share of employee option
grants within the year
|
|
$ |
4.08 |
|
|
$ |
6.70 |
|
|
Cash received upon exercise of options
|
|
|
39 |
|
|
|
26 |
|
|
| Schedule of Restricted Stock Awards Under the 2012 and 2013 Plans |
Restricted stock awards under the 2012 and 2013 plans are
summarized as follows:
|
|
|
|
|
|
|
|
|
| |
|
Number of
Shares |
|
|
Weighted Average
Grant Date Fair
Value |
|
|
Unvested at December 31, 2014
|
|
|
8,493 |
|
|
$ |
1.04 |
|
|
Vesting of restricted stock
|
|
|
(3,303 |
) |
|
|
1.00 |
|
|
|
|
|
|
|
|
|
|
|
Unvested at December 31, 2015
|
|
|
5,190 |
|
|
$ |
1.07 |
|
|
|
|
|
|
|
|
|
|
|
| Summary of Stock-Based Compensation |
Stock-based compensation is as follows:
|
|
|
|
|
|
|
|
|
| |
|
Years Ended December 31, |
|
| |
|
2015 |
|
|
2014 |
|
|
Research and development
|
|
$ |
451 |
|
|
$ |
181 |
|
|
General and administrative
|
|
|
777 |
|
|
|
366 |
|
|
|
|
|
|
|
|
|
|
|
Total stock-based compensation expense
|
|
$ |
1,228 |
|
|
$ |
547 |
|
|
|
|
|
|
|
|
|
|
|
| Summary of Weighted-Average Assumptions Used in the Black-Scholes Option Pricing Model to Determine the Fair Value of the Employee Stock Option Grants |
The weighted-average assumptions used in the Black-Scholes option
pricing model to determine the fair value of the employee stock
option grants were as follows:
|
|
|
|
|
|
|
|
|
| |
|
Years Ended December 31, |
|
| |
|
2015 |
|
|
2014 |
|
|
Risk-free interest rate
|
|
|
1.68 |
% |
|
|
1.83 |
% |
|
Expected volatility
|
|
|
62.6 |
% |
|
|
104.5 |
% |
|
Expected term (in years)
|
|
|
6.04 |
|
|
|
6.08 |
|
|
Expected dividend yield
|
|
|
0.0 |
% |
|
|
0.0 |
% |
|
| Summary of Weighted-Average Assumptions Used in the Black-Scholes Option Pricing Model to Determine the Fair Value of the Non-Employee Stock Option Grants |
The weighted-average assumptions used in the Black-Scholes option
pricing model to determine the fair value of the non-employee stock
option grants were as follows:
|
|
|
|
|
|
|
|
|
| |
|
Years Ended December 31, |
|
| |
|
2015 |
|
|
2014 |
|
|
Risk-free interest rate
|
|
|
1.79 |
% |
|
|
0.89 |
% |
|
Expected volatility
|
|
|
63.2 |
% |
|
|
99.4 |
% |
|
Expected term (in years)
|
|
|
6.16 |
|
|
|
2.47 |
|
|
Expected dividend yield
|
|
|
0.0 |
% |
|
|
0.0 |
% |
|