Stock Incentive Plans (Tables)
|
6 Months Ended |
Jun. 30, 2018 |
|---|
| Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] |
|
| Schedule of Stock-Based Compensation Expense |
Total stock-based compensation expense for employees, directors and non-employees for the three and six months ended June 30, 2018 and 2017 is as follows:
|
|
|
Three months ended June 30, |
|
|
Six months ended June 30, |
|
|
|
|
2018 |
|
|
2017 |
|
|
2018 |
|
|
2017 |
|
|
Research and development |
|
$ |
167,306 |
|
|
$ |
11,262 |
|
|
$ |
300,347 |
|
|
$ |
22,123 |
|
|
General and administrative |
|
|
401,766 |
|
|
|
19,316 |
|
|
|
648,845 |
|
|
|
36,135 |
|
|
|
|
$ |
569,072 |
|
|
$ |
30,578 |
|
|
$ |
949,192 |
|
|
$ |
58,258 |
|
|
| Schedule of Stock Options Valuation Assumptions Using a Black-Scholes Option Pricing Model |
The assumptions used in Black-Scholes option pricing model for the three and six months ended June 30, 2018 and 2017 are as follows:
|
|
|
Three months ended June 30, |
|
Six months ended June 30, |
|
|
|
2018 |
|
2017 |
|
2018 |
|
2017 |
|
Expected volatility |
|
56.36% |
|
53.52% |
|
52.80% - 60.12% |
|
53.52% - 53.53% |
|
Weighted-average risk-free interest rate |
|
2.84% |
|
2.00% |
|
2.33% - 2.84% |
|
2.00% - 2.28% |
|
Expected dividend yield |
|
— % |
|
— % |
|
— % |
|
— % |
|
Expected term (in years) |
|
6.25 |
|
6.25 |
|
5.5 - 7.6 |
|
6.25 |
|
Underlying common stock fair value |
|
$20.98 |
|
$0.63 |
|
$6.63 - $20.98 |
|
$0.63 |
|
| Summary of Option Activity under Plans |
A summary of option activity under the Plans for the six months ended June 30, 2018 is as follows:
|
|
|
Number of Options |
|
|
Weighted-
Average Exercise
Price per Share |
|
|
Weighted-
Average Remaining
Contractual Term
(in Years) |
|
|
Aggregate
Intrinsic Value |
|
|
Outstanding at January 1, 2018 |
|
|
1,971,711 |
|
|
$ |
3.61 |
|
|
|
9.3 |
|
|
$ |
5,977,162 |
|
|
Granted |
|
|
793,287 |
|
|
$ |
15.96 |
|
|
|
|
|
|
|
|
|
|
Exercised |
|
|
(53,884 |
) |
|
$ |
1.58 |
|
|
|
|
|
|
|
|
|
|
Cancelled/Forfeited |
|
|
(69,314 |
) |
|
$ |
2.82 |
|
|
|
|
|
|
|
|
|
|
Outstanding at June 30, 2018 |
|
|
2,641,800 |
|
|
$ |
7.37 |
|
|
|
9.1 |
|
|
$ |
34,438,555 |
|
|
Exercisable at June 30, 2018 |
|
|
454,799 |
|
|
$ |
2.45 |
|
|
|
8.4 |
|
|
$ |
8,163,075 |
|
|
Expected to vest at June 30, 2018 |
|
|
2,187,001 |
|
|
$ |
8.97 |
|
|
|
9.3 |
|
|
$ |
26,008,045 |
|
|
| Summary of Unvested Common Stock from Early Exercises Subject to Repurchase |
A summary of the Company’s unvested common stock from early exercises that is subject to repurchase by the Company is as follows:
|
|
|
Shares |
|
|
Unvested shares - January 1, 2018 |
|
|
265,098 |
|
|
Vested |
|
|
(61,501 |
) |
|
Exercised |
|
|
16,150 |
|
|
Repurchased |
|
|
— |
|
|
Unvested shares - June 30, 2018 |
|
|
219,747 |
|
|