9.	Stockholders’ Equity

Common Stock

On July 1, 2015, the Company completed an IPO, and issued and sold 8,545,138 shares of common stock at a public offering price of $18.00 per share, resulting in net proceeds of approximately $139,267 after deducting underwriting discounts and commissions and other offering expenses totaling $3,748. The shares issued upon closing of the IPO included 1,114,583 shares of the Company’s common stock, which were sold to the underwriters pursuant to the full exercise of their option to purchase additional shares of common stock. Upon the listing of the Company’s common stock on the NASDAQ on June 26, 2015, all outstanding shares of the Company’s convertible preferred stock automatically converted into 22,866,987 shares of the Company’s common stock.

As of December 31, 2014, the Company’s Amended and Restated Certificate of Incorporation, as further amended, authorized the Company to issue 38,000,000 shares of common stock, $0.001 par value per share. On July 1, 2015, in connection with the closing of the IPO, the Company effected its Restated Certificate of Incorporation, which authorizes the Company to issue 200,000,000 shares of common stock, $0.001 par value per share.

Common Stock Warrant

In June 2014, the Company entered into a research agreement with the Mayo Foundation for Medical Education and Research (“Mayo”) under which the Company acquired a license to intellectual property. In exchange for the license, the Company issued to Mayo a warrant to purchase 454,545 shares of common stock at an exercise price of $0.01 per share, which was immediately exercisable. Upon issuance of the warrant, the Company recorded research and development expense of $317 for the fair value of the warrant, determined using the following assumptions in the Black-Scholes option-pricing model: expected volatility of 86.0%, risk-free interest rate of 2.3%, expected term of seven years (equaling the contractual term of the warrant) and no expected dividends. Because this warrant was indexed to the Company’s stock and could only be settled by gross physical delivery of shares the Company determined that this warrant qualifies for equity classification. This warrant was exercised on April 29, 2015.

The Company also issued to Mayo an additional warrant (the “performance warrant”) to purchase up to 284,090 shares of common stock at an exercise price equal to the per share price at which the Company most recently sold shares of its preferred stock. The performance warrant was exercisable for a number of shares to be determined by the Company’s board of directors from time to time, upon the achievement by Mayo of specified milestones related. The performance warrant provided for termination upon the closing of an initial public offering by the Company. The IPO closed prior to any probable achievement of the specified milestones, therefore, the warrant terminated and the Company did not record any expense for the performance warrant from the date of issuance through the closing of the IPO.

2012 Stock Incentive Plan

The Company’s 2012 Stock Incentive Plan, as amended, (the “2012 Plan”) provides for the Company to sell or issue common stock or restricted common stock, or to grant incentive stock options or nonqualified stock options for the purchase of common stock, to employees, members of the board of directors and consultants of the Company. The 2012 Plan is administered by the board of directors, or at the discretion of the board of directors, by a committee of the board. The exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, or their committee if so delegated, except that the exercise price per share of stock options may not be less than 100% of the fair market value of the share of common stock on the date of grant and the term of stock option may not be greater than ten years. The Company generally grants stock-based awards with service conditions only (“service-based” awards). Stock options granted generally vest over four years and expire after ten years, although options have been granted with vesting terms less than four years.

2015 Incentive Award Plan

On June 16, 2015, the Company’s stockholders approved the 2015 Incentive Award Plan (the “2015 Plan”), which became effective on June 25, 2015. The 2015 Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. The number of shares initially reserved for issuance under the 2015 Plan is the sum of (i) 2,200,000 shares of common stock and (ii) the number of shares subject to awards outstanding under the 2012 Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company on or after the effective date of the 2015 Plan. In addition, the number of shares of common stock that may be issued under the 2015 Plan is subject to increase on the first day of each calendar year, beginning in 2016 and ending in 2025, equal to the lesser of (i) 4% of the number of shares of the Company’s common stock outstanding on the last day of the preceding applicable calendar year and (ii) an amount determined by the Company’s board of directors.

2015 Employee Stock Purchase Plan

On June 16, 2015, the Company’s stockholders approved the 2015 Employee Stock Purchase Plan (the “ESPP”), which became effective on June 25, 2015. A total of 365,000 shares of common stock were reserved for issuance under the ESPP. In addition, the number of shares of common stock that may be issued under the ESPP will automatically increase on the first day of each calendar year, beginning in 2016 and ending in 2025, by an amount equal to the least of (i) 400,000 shares, (ii) 1% of the number of shares of the Company’s common stock outstanding on the last day of the applicable preceding calendar year and (iii) an amount determined by the Company’s board of directors. Offering periods under the ESPP will commence when determined by the plan administrator.

Stock Options

The following table summarizes the Company’s stock option activity since December 31, 2014:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(in years)
Outstanding as of December 31, 2014		3,579,342		$	1.38		9.21	$	59,498
Granted		1,540,124			18.26
Exercised		(206,720	)		0.44
Forfeited		(70,250	)		5.04
Outstanding as of September 30, 2015		4,842,496		$	6.73		8.89	$	111,830
Options exercisable as of September 30, 2015		1,279,950		$	0.60		8.26	$	37,168
Options vested and expected to vest as of September 30, 2015		4,842,496		$	6.73		8.89	$	111,830

The weighted average grant-date fair value of stock options granted during the three and nine months ended September 30, 2015 was $29.25 and $13.00 per share, respectively.

During the nine months ended September 30, 2015, the Company granted performance-based stock options to employees for the purchase of an aggregate of 30,000 shares of common stock with a grant date fair value of $12.89 per share. These stock options are exercisable only upon achievement of specified performance targets. As of September 30, 2015, none of these options were exercisable because none of the specified performance targets had been achieved. Because achievement of the specified performance targets was not deemed probable as of September 30, 2015, the Company did not record any expense for these stock options from the dates of issuance through September 30, 2015.

As of September 30, 2015, there were outstanding unvested service-based stock options held by non-employees for the purchase of 32,125 shares of common stock.

Restricted Common Stock

The Company has granted restricted common stock with time-based vesting conditions. Unvested shares of restricted common stock may not be sold or transferred by the holder. These restrictions lapse according to the time-based vesting conditions of each award. The table below summarizes the Company’s restricted stock activity since December 31, 2014:

	Number of Shares			Weighted Average Grant Date Fair Value
Unvested restricted common stock as of December 31, 2014		52,500		$	0.001
Vested		(51,875	)	$	0.001
Unvested restricted common stock as of September 30, 2015		625		$	0.001

Stock-based Compensation Expense

The Company recorded stock-based compensation expense related to stock options and restricted common stock in the following expense categories of its consolidated statements of operations and comprehensive loss:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Research and development expenses	$	1,304	$	272	$	3,818	$	344
General and administrative expenses		1,203		331		3,089		356
	$	2,507	$	603	$	6,907	$	700