Annual report pursuant to Section 13 and 15(d)

Stock and Employee Benefit Plans (Tables)

v3.21.1
Stock and Employee Benefit Plans (Tables)
12 Months Ended
Dec. 31, 2020
Share-based Payment Arrangement [Abstract]  
Schedule of Fair Value Assumptions
The Company estimates the fair value of each stock award on the grant date using the Black-Scholes option-pricing model based on the following assumptions:
  Years Ended December 31,
  2020 2019
Risk free interest rate
0.33% - 1.53%
1.41% - 2.60%
Expected term (in years)
5.00 - 5.73
5 - 5.73
Dividend yield —  — 
Expected volatility
70.0% - 75.8%
81.7% - 81.8%
The fair value of shares expected to be purchased under the 2018 ESPP using the Black-Scholes model with the following assumptions:
  Years Ended December 31,
  2020 2019
Risk free interest rate
0.10% - 0.18%
2.48  %
Expected term (in years) 0.5 years 0.5 years
Dividend yield —  — 
Expected volatility
74.36% - 120.89%
57.57  %
Schedule of Stock Option Activity
The following table summarizes stock option activity for employees and non-employees:
Number of
Options
Weighted-
Average
Exercise
Price
Weighted-
Average
Remaining
Contractual
Life
Aggregate
Intrinsic
Value
(in thousands)
Outstanding, December 31, 2019 8,259,915  $ 3.60  $ 7,987 
Granted 2,311,481  3.15  — 
Exercised 149,406  1.95  97 
Canceled 830,867  4.58  101 
Outstanding, December 31, 2020 9,591,123  $ 3.44  6.84 years $ 2,303 
Vested or expected to vest, December 31, 2020 9,591,123  $ 3.44  6.84 years $ 2,303 
Exercisable, December 31, 2020 6,123,532  $ 3.28  5.81 years $ 2,269 
The following table summarizes stock option activity for these inducement options (in thousands):
Number of
Options
Weighted-
Average
Exercise
Price
Weighted-
Average
Remaining
Contractual
Life
Aggregate
Intrinsic
Value
(in thousands)
Outstanding, December 31, 2019 1,200,000  $ 4.36  $ 130 
Granted —  $ —  $ — 
Canceled or Expired 779,687  $ 4.01  $ — 
Outstanding, December 31, 2020 420,313  $ 5.00  8.12 years $ — 
Vested or expected to vest 420,313  $ 5.00  8.12 years $ — 
Exercisable, December 31, 2020 214,063  $ 5.34  7.60 years $ — 
Schedule of Stock-Based Compensation Expense
Total stock-based compensation expense is recorded in operating expenses based upon the functional responsibilities of the individuals holding the respective options as follows (in thousands):
  Years Ended December 31,
  2020 2019
Research and development $ 2,394  $ 2,446 
General and administrative 2,696  2,928 
Total stock-based compensation $ 5,090  $ 5,374