Annual report pursuant to Section 13 and 15(d)

Stock Plans and Stock-Based Compensation (Tables)

v3.21.1
Stock Plans and Stock-Based Compensation (Tables)
12 Months Ended
Dec. 31, 2020
Share-based Payment Arrangement [Abstract]  
Summary of Stock Option Grants, Including Performance Options
The following table summarizes activity in the Company’s stock option grants, including performance options:
 
    
Shares

Subject to

Outstanding

Options
    
Weighted

Average

Exercise

Price of

Options
    
Weighted

Average

Remaining

Contractual

Term

(Years)
    
Aggregate

Intrinsic

Value
(in thousands)
 
Outstanding as of December 31, 2019
     6,726,695      $ 7.88                    
Options granted
     3,611,593        4.84                    
Options exercised
     (63,633      1.44                    
Options forfeited
     (492,931      11.46                    
Options expired
     (970,094      9.02                    
    
 
 
                            
Outstanding as of December 31, 2020
     8,811,630      $ 6.35        7.60      $ 9,507  
    
 
 
                            
Vested and expected to vest as of December 31, 2020
  
 
8,811,630
 
  
 
6.35
 
  
 
7.60
 
  
$
9,507
 
    
 
 
                            
Exercisable as of December 31, 2020
     4,789,242      $ 6.57        6.49      $ 5,734  
    
 
 
                            
Summary of Stock-Based Compensation Expense
Stock-based compensation expense is included in the consolidated statements of operations and comprehensive loss and is as follows (in thousands):
 
    
Year Ended
December 31,
 
    
2020
    
2019
 
Research and development
   $ 2,739      $ 4,361  
General and administrative
     4,396        5,197  
Restructuring charges
     189        910  
    
 
 
    
 
 
 
Total stock-based compensation expense
   $ 7,324      $ 10,468  
    
 
 
    
 
 
 
Estimated Weighted-Average Grant Date Fair Value
The following table presents the weighted-average assumptions the Company used in the Black-Scholes option-pricing model to derive the grant date fair values of stock options granted in each of the years presented along with the resulting estimated weighted-average grant date fair values per share:
 
    
Year Ended
December 31,
 
    
2020
   
2019
 
Expected term (years)
     6.1       6.2  
Expected volatility
     105     76
Risk-free interest rate
     0.4     2.1
Expected dividend yield
     —         —    
Weighted-average grant date fair value per share
   $ 3.91     $ 5.60