Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock-Based Compensation Expense

Total stock-based compensation expense related to the Company’s equity incentive plans and 2016 ESPP was as follows (in thousands):

	Three Months Ended
	March 31,
	2018		2017
Research and development	$	323	$	110
General and administrative		512		291
Total stock-based compensation expense	$	835	$	401

Schedule of Estimated Fair Value of Stock Options Granted

The following table summarizes the weighted-average Black-Scholes option pricing model assumptions used to estimate the fair value of stock options granted under the equity incentive plans and the shares purchasable under the 2016 ESPP during the periods presented:

	Three Months Ended
	March 31,
	2018			2017
Equity Incentive Plans
Expected term		6.01			5.99
Expected volatility		85	%		86	%
Risk-free interest		2.72	%		2.13	%
Dividend yield		0	%		0	%
2016 ESPP
Expected term		0.49			0.50
Expected volatility		69	%		79	%
Risk-free interest		2.00	%		0.68	%
Dividend yield		0	%		0	%