Incentive Stock Plan”) that governs stock awards made to employees and directors prior to completion of the IPO.

November

2014,

April

2015,

’s stockholders, approved the Company’s Equity Incentive Plan (the Plan”) which became effective in The Plan provides for the grant of stock options, other forms of equity compensation, and performance cash awards. The maximum number of shares of common stock that be issued under the Plan is as of In addition, the number of shares of common stock reserved for issuance under the Plan will automatically increase on of each year, beginning on and ending on and including by of the total number of shares of the Company’s capital stock outstanding on of the preceding calendar year, or a lesser number of shares determined by the Board. Pursuant to the terms of the Plan, on the common stock reserved for issuance under the Plan automatically increased by  shares.

December

31,

2016,

14,933

$71,000

$169,000.

stock options to acquire shares of common stock were exercised for approximately  with an intrinsic value of No stock options were exercised during the year ended

r the Incentive Stock Plan and the Plan is included in the following line items in the accompanying statements of operations (in thousands):

cted dividend yield and the risk-free interest rate for the expected term of the option. The expected term represents the period of time the stock options are expected to be outstanding. Due to the lack of sufficient historical exercise data to provide a reasonable basis upon which to otherwise estimate the expected term of the stock options, the Company uses the simplified method to estimate the expected term for its “plain vanilla” stock options. Under the simplified method, the expected term of an option is presumed to be the mid-point between the vesting date and the end of the contractual term. Some options, for example those that have exercise prices in excess of the fair value of the underlying stock, are not considered “plain vanilla” stock options. For these options, the Company uses an expected term equal to the contractual term of the option. Expected volatility is based on historical volatilities for publicly traded stock of comparable 

ies over the estimated expected term of the stock options. The Company assumes no dividend yield because dividends are not expected to be paid in the near future, which is consistent with the Company’s history of not paying dividends.

zes compensation expense related to stock-based payment transactions upon satisfaction of the requisite service or vesting requirements. Forfeitures are estimated at the time of grant and revised based on actual forfeitures, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

December

31,

2016,

2015

2014,

$9.25,

$10.63

$4.50

re, respectively. The assumptions used to estimate fair value are as follows:

2014

for the year ended is summarized as follows:

December

31,

2016,

December

31,

2016,

2015

2014,

$5.4

$1.1

$0.2

December

31,

2016

were as follows:

December

31,

2016,

$10.6

ncentive Stock Plan and Plan. That compensation cost is expected to be recognized over a weighted-average period of  years.

December

31,

2016,

$44,000

elated to performance-based awards included in research and development expenses. These awards were in connection with the strategic initiatives set for the award that were achieved in exercisable for an aggregate of  shares of common stock during the year ended

December

31,

2015,

$0.7

elated to performance-based awards included in general and administrative expenses and million of stock-based compensation expense related to performance-based awards included in research and development expenses. These awards were in connection with the grant of fully vested stock options exercisable for an aggregate of shares of common stock during the year ended The Company did not recognize any stock-based compensation expense related to performance-based incentive awards during 

December

31,

2014,