9. Stock Incentive Plans

Prior to the Company's initial public offering in June 2015 (the “IPO”), the Company granted awards to eligible participants under its 2008 Equity Incentive Plan. In May 2015, the Company’s board of directors adopted and, in June 2015, the Company’s stockholders approved the 2015 Stock Incentive Plan (“2015 Plan”), which became effective immediately prior to the effectiveness of the IPO. Subsequent to the IPO, option grants are awarded to eligible participants only under the 2015 Plan.

The 2015 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock-based awards. The Company’s employees, officers, directors and consultants and advisors are eligible to receive awards under the 2015 Plan.

Terms of stock option agreements, including vesting requirements, are determined by the Company's board of directors, subject to the provisions of the applicable stock incentive plan. Options granted by the Company generally vest ratably over four years, with a one-year cliff, and options are exercisable from the date of grant for a period of ten years. For options granted through June 30, 2019, the exercise price or purchase price, as applicable, equaled the estimated fair value of the common stock as determined by the Company's board of directors on the date of grant.

A summary of the Company’s stock option activity and related information follows:


				Weighted
				Average
		Weighted-		Remaining	Aggregate
		Average		Contractual	Intrinsic Value
	Shares	Exercise Price		Term (years)	(in thousands)
Outstanding at December 31, 2018	433,389	$	29.05	7.97	$	—
Granted	372,320	$	4.52
Cancelled or forfeited	(42,117)	$	30.00
Outstanding at June 30, 2019	763,592	$	17.04	8.52	$	1,421
Vested and Exercisable at June 30, 2019	201,831	$	44.29	6.32	$	9

There were no options exercised in the three and six months ended June 30, 2019. The total intrinsic value of options exercised for the three and six months ended June 30, 2018 was $1 thousand. The total fair value of employee and non-employee options vested for the three months ended June 30, 2019 and 2018 was $0.4 million and $0.5 million, respectively. The total fair value of employee and non-employee options vested for the six months ended June 30, 2019 and 2018 was $0.8 million and $1.1 million, respectively. The weighted-average grant date fair value of options granted to employees and non-employees for the three months ended June 30, 2019 and 2018 was $4.00 and $10.30, respectively. The weighted-average grant date fair value of options granted to employees and non-employees for the six months ended June 30, 2019 and 2018 was $3.06 and $8.90, respectively.

At June 30, 2019, the total unrecognized compensation expense related to unvested stock option awards was $2.3 million. The Company expects to recognize that cost over a weighted-average period of approximately 2.1 years.