Stockholders' Equity (Deficit)

9 Months Ended

Sep. 30, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

8.Stockholders’ Equity (Deficit)

Equity incentive plan

Under the Company’s 2011 Stock Incentive Plan (the “2011 Plan”), the Company may grant options to purchase common stock, restricted stock awards, or directly issue shares of common stock to employees, directors and consultants of the Company. Under the 2011 Plan, options granted are exercisable over a maximum term of 10 years from the date of grant and generally vest over a period of four years. The Company adopted a 2018 Omnibus Incentive Plan (the “2018 Plan”), effective January 2018. The 2018 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock, restricted stock units, dividend equivalent rights and other stock and cash-based awards (including annual cash incentives and long-term cash incentives). The Company has reserved 3,000,000 shares of common stock for issuance pursuant to awards under the 2018 Plan. As of September 30, 2018, the Company has 2,195,901 shares of common stock available for issuance under the 2018 Plan.

The Company adopted a 2018 Employee Stock Purchase Plan (“ESPP”) in January 2018. The ESPP enables eligible employees of the Company and designated affiliates to purchase shares of common stock at a discount of 15%. Six month offer periods under the ESPP commenced on September 1, 2018. The Company has reserved 325,000 shares of common stock for issuance under the ESPP.

Total stock-based compensation expense for employees and non-employees recognized in the statements of operations was as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
	(unaudited)				(unaudited)
Research and development	$	475	$	322	$	1,217	$	676
General and administrative		519		267		1,347		541
Total stock-based compensation expense	$	994	$	589	$	2,564	$	1,217

The table below summarizes stock option and restricted award activity under the 2011 and 2018 Plan:

	Number of Shares Outstanding			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in thousands)
Balances at December 31, 2017		2,506,926		$	3.50		8.79	$	24,033
Forfeited		(6,772	)	$	7.01
Exercised		(254,186	)	$	1.94				1,786
Granted		804,099		$	9.87
Balances at September 30, 2018		3,050,067		$	5.31		8.53	$	14,880