In August 2020, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with Cowen and Company, LLC and Piper Sandler & Co., as representatives of the several underwriters named therein (collectively, the “Underwriters”), in connection with the issuance and sale by the Company in a public offering of 10,500,000 shares of the Company’s common stock at a public offering price of $21.50 per share, less underwriting discounts and commissions, pursuant to an effective shelf registration statement on Form S-3 (Registration No. 333-244401) and a related prospectus supplement filed with the Securities and Exchange Commission (the “SEC” and such public offering, the “offering”). Under the terms of the Underwriting Agreement, the Company granted the Underwriters an option exercisable for 30 days to purchase up to an additional 1,575,000 shares of its common stock at the public offering price, less underwriting discounts and commissions, which the underwriters exercised in full.

In August 2020, the Company entered into the Securities Purchase Agreement with Nestlé for the sale by the Company of 959,002 shares of the Company’s common stock at a purchase price of $20.855 per share (the “concurrent placement”). The Company received aggregate net proceeds from the concurrent placement of approximately $19,900 after deducting offering expenses payable by the Company. The consummation of the concurrent placement was contingent upon the closing of the offering and the satisfaction of certain other customary conditions. The shares were offered and sold to Nestlé pursuant to an effective registration statement on Form S-3 (File No. 333-237033) and a related prospectus supplement filed with the SEC.

In November 2019, the Company entered into a sales agreement (the, “2019 Sales Agreement”), with Cowen to sell shares of its common stock with aggregate gross sales proceeds of up to $25,000, from time to time, through an ATM under which Cowen acts as sales agent. On March 18, 2020, in connection with filing an updated registration statement on Form S-3 (File No. 333-237033), the Company entered into a Sales Agreement (the “2020 Sales Agreement”), with Cowen on substantially the same terms as the 2019 Sales Agreement and terminated the 2019 Sales Agreement. From January 1, 2020 to September 30, 2020 the Company sold 5,787,681 shares of common stock under the 2019 Sales Agreement and the 2020 Sales Agreement, as applicable, at an average price of approximately $4.40 per share, raising aggregate net proceeds of approximately $24,772 after deducting an aggregate commission of approximately 3%.

The following table summarizes the Company’s stock option activity since December 31, 2019:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(in years)
Outstanding as of December 31, 2019		8,310,683		$	10.36		7.01	$	3,427
Granted		4,574,365			4.59
Exercised		(1,969,308	)		6.15
Forfeited		(1,113,107	)		10.66
Outstanding as of September 30, 2020		9,802,633		$	8.47		7.93	$	196,033
Options exercisable as of September 30, 2020		3,264,289		$	14.60		5.91	$	46,335

The weighted average grant-date fair value of stock options granted during the three and nine months ended September 30, 2020 and 2019 was $18.12, $3.03, $2.12 and $5.67 per share, respectively.

During the three months ended March 31, 2019, the Company granted performance-based stock options to employees for the purchase of an aggregate of 1.1 million shares of common stock with a grant date fair value of $4.58 per share. These stock options are exercisable only upon achievement of specified performance targets. As of September 30, 2020, 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, 2020, the Company did not record any expense for these stock options from the dates of issuance through September 30, 2020.

The Company has granted restricted stock units with time-based vesting conditions. The table below summarizes the Company’s restricted stock unit activity since December 31, 2019:

	Number of Shares			Weighted Average Grant Date Fair Value
Unvested restricted stock units as of December 31, 2019		130,000		$	8.86
Granted		—			—
Forfeited		(5,000	)	$	2.29
Vested		(125,000	)	$	9.12
Unvested restricted stock units as of September 30, 2020		—		$	—

The Company recorded stock-based compensation expense in the following expense categories of its condensed consolidated statements of operations and comprehensive loss (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Research and development expenses	$	1,368	$	1,033	$	3,358	$	3,574
General and administrative expenses		881		1,004		2,764		2,625
	$	2,249	$	2,037	$	6,122	$	6,199