Stockholders' Equity

12 Months Ended

Dec. 31, 2021

Stockholders Equity Note [Abstract]

Stockholders' Equity

7. Stockholders’ Equity

Preferred Stock

As of December 31, 2021 and 2020, the Company’s restated certificate of incorporation authorized the Company to issue 5,000,000 shares of preferred stock, with a par value of $0.001 per share.

Common Stock

As of December 31, 2021 and 2020, the Company’s restated certificate of incorporation authorized the Company to issue 200,000,000 shares of common stock, with a par value of $0.001 per share.

As of December 31, 2021 and 2020, the Company had reserved shares of common stock for future issuance as shown in the table below:

	December 31, 2021		December 31, 2020
Shares of common stock reserved for future issuance under the 2012 Stock Incentive Plan		665,720		921,824
Shares of common stock reserved for future issuance under the 2019 Stock Incentive Plan		3,400,489		2,396,922
Shares of common stock reserved for future issuance under the 2019 Employee Stock Purchase Plan		470,631		327,454
Shares to be issued upon conversion of common stock warrants and prefunded warrants		20,602,244		—
Shares to be issued upon sales under the LPC Purchase Agreement		30,000,000		—
		55,139,084		3,646,200

At-the-Market Offering

In June 2020, the Company entered into the ATM Sales Agreement with SVB Leerink LLC, under which the Company may issue and sell shares of its common stock, from time to time, having an aggregate offering price of up to $12.0 million. Sales of common stock under the ATM Sales Agreement may be made by any method that is deemed an “at-the-market” offering as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended. The Company is not obligated to make any sales of its common stock under the ATM Sales Agreement. The Company began making sales pursuant to the ATM Sales Agreement in July 2020, and as of December 31, 2021, the Company had issued and sold an aggregate of 3,583,394 shares of common stock for gross proceeds of $11.0 million, before deducting estimated commissions and allocated fees of $0.8 million. Under the terms of the October 2021 Private Placements, as described below, the Company agreed not to issue or sell additional shares under the ATM Sales Agreement on or prior to January 4, 2022.

Equity Purchase Agreement

On June 18, 2021, the Company entered into a common stock purchase agreement (“LPC Purchase Agreement”) with Lincoln Park Capital Fund, LLC (“Lincoln Park”). The LPC Purchase Agreement provides that, subject to the terms and conditions therein, the Company has the right, but not the obligation, to sell, at its discretion, to Lincoln Park up to $15.0 million of shares of common stock over a 24-month period commencing on July 23, 2021. In addition, under the LPC Purchase Agreement, the Company issued 170,088 shares of common stock to Lincoln Park as consideration for Lincoln Park’s commitment to purchase shares of the Company’s common stock under the LPC Purchase Agreement. The purchase price per share of the shares sold will be based on the market prices prevailing immediately preceding the time of sale as computed under the LPC Purchase Agreement. Lincoln Park has covenanted not to cause or engage in any manner whatsoever, any direct or indirect short selling or hedging of the Company’s common stock. The agreement may be terminated by the Company at any time, at its sole discretion, without any additional cost or penalty. Under the terms of the

October 2021 Private Placements, the Company agreed to not issue or sell additional shares under the LPC Purchase Agreement on or prior to April 6, 2023.

Private Placements

On October 5, 2021, the Company issued and sold to an initial investor in a private placement priced at-the-market under Nasdaq rules, (i) 2,373,201 shares of the Company’s common stock and accompanying warrants to purchase an aggregate of 4,746,402 shares of the Company’s common stock, and (ii) pre-funded warrants to purchase up to an aggregate of 4,926,069 shares of the Company’s common stock and accompanying warrants to purchase an aggregate of 9,852,138 shares of the Company’s common stock. Each share of the Company’s common stock and accompanying common stock warrants were sold together at a combined price of $1.62, and each pre-funded warrant and accompanying common stock warrants were sold together at a combined price of $1.619, for gross proceeds of approximately $11.8 million. Each pre-funded warrant had an exercise price of $0.001 per share, became exercisable immediately upon issuance and was exercisable until exercised in full. Of the accompanying common stock warrants, warrants to purchase an aggregate of 7,299,270 shares will expire on April 5, 2025, and warrants to purchase an aggregate of 7,299,270 shares will expire on October 5, 2028. The accompanying common stock warrants have an exercise price of $1.37 per share and became exercisable immediately upon issuance.

On October 18, 2021, the Company issued and sold to New Enterprise Associates 16, L.P., an existing stockholder of the Company (“NEA”) and related party, in a private placement, 1,851,852 shares of the Company’s common stock and accompanying warrants to purchase an aggregate of 3,703,704 shares of the Company’s common stock. Each share of the Company’s common stock and accompanying common stock warrants were sold together at a combined price of $1.62 for gross proceeds of approximately $3.0 million. Of the accompanying common stock warrants, warrants to purchase an aggregate of 1,851,852 shares of the Company’s common stock will expire on April 18, 2025, and warrants to purchase an aggregate of 1,851,852 shares of the Company’s common stock will expire on October 18, 2028. The accompanying common stock warrants have an exercise price of $1.37 per share and became exercisable immediately upon issuance.

Total net proceeds from the two October private placements were $13.7 million, after deducting issuance costs of $1.1 million.

Warrant activity, including activity related to the pre-funded warrants, for the year ended December 31, 2021 is shown in the table below:

	Number of Warrant Shares			Weighted Average Exercise Price		Weighted Average Contractual Term
						(in years)
Outstanding as of December 31, 2020		—		$	—		—
Issued		23,228,313		$	1.08
Exercised		(2,626,069	)	$	0.001
Outstanding as of December 31, 2021		20,602,244		$	1.22		4.5

Only pre-funded warrants were exercised in 2021. Subsequent to December 31, 2021, the remaining pre-funded warrants to purchase 2,300,000 shares of the Company’s common stock were exercised at a price of $0.001 per share. The pre-funded and common stock warrants are classified as equity in accordance with ASC 815 given that the pre-funded and common stock warrants are indexed to the Company’s own shares of common stock and meet the requirements to be classified in permanent equity.

Stock Based Awards

In April 2019, the Company’s board of directors adopted the 2019 Stock Incentive Plan (the “2019 Plan”), which became effective on May 7, 2019. The 2019 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. The Company’s employees, officers, directors, consultants and advisors are eligible to receive awards under the 2019 Plan. The 2019 Plan is administered by the Company’s board of directors.

The total number of shares of common stock that may be issued under the 2019 Plan and the 2012 Stock Incentive Plan (the “2012 Plan”) was 4,066,209 and 3,318,746 as of December 31, 2021 and 2020, respectively, of which 1,136,737 and 1,147,269 shares remained available for grant under the 2019 Plan, respectively. Awards may be made under the 2019 Plan for up to such number of shares of the Company’s common stock as is equal to the sum of: i) 1,578,947 shares; plus ii) the number of shares (up to 1,157,894 shares) equal to the number of shares of the Company’s common stock subject to outstanding awards under the 2012 Stock Incentive Plan (the “2012 Plan”) that expire, terminate or are otherwise cancelled,

forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right; plus iii) an annual increase to be added on the first day of each fiscal year, beginning with 2020 and continuing through 2029, equal to the least of (a) 2,105,623 shares of common stock, (b) 4% of the number of outstanding shares of the Company’s common stock on such date, and (c) an amount determined by the Company’s board of directors. Effective January 1, 2021 and January 1, 2020, respectively, the number of shares reserved for issuance under the 2019 Plan increased, pursuant to the terms of the 2019 Plan, by an additional 741,871 shares and 713,383 shares, equal to 4% of the Company’s then-outstanding common stock.

The 2012 Plan was adopted by the Company’s board of directors and stockholders. The 2012 Plan provides for the issuance of stock-based awards to the Company’s employees, officers, directors, consultants and advisors. The Company’s board of directors administers the 2012 Plan. In April 2019, the Company’s board of directors adopted a resolution effective on May 7, 2019, that no further equity-based awards may be granted under the 2012 Plan.

Options granted under the 2019 Plan and the 2012 Plan have a maximum term of ten years. Options granted to employees, officers and non-employees generally vest over four years based on varying vesting schedules that primarily include: 25% vesting on the first anniversary date of grant and the balance ratably over the next 36 months or vesting in equal monthly or quarterly installments over four years. Options granted to directors generally vest over one to two years. As of December 31, 2021 and 2020, respectively, options to purchase 2,263,752 and 1,249,653 shares of common stock were granted and outstanding, net of cancelations, under the 2019 Plan. As of December 31, 2021 and 2020, respectively, options to purchase 665,720 and 921,824 shares of common stock were granted and outstanding, net of cancellations, under the 2012 Plan.

In February 2021, the compensation committee of the Company’s board of directors approved the grant of 450,875 stock options with performance-based vesting (“PSOs”) to employees of the Company. The PSOs granted in February 2021, vest based on the timing and successful results of the Company’s PRISM or CANAL clinical trials.

A summary of the Company’s combined stock option activity for the 2019 Plan and the 2012 Plan for the year ended December 31, 2021 is as follows:

	Number of Option Shares			Weighted Average Exercise Price		Weighted Average Contractual Term		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding as of December 31, 2020		2,171,477		$	5.62		7.5	$	185
Granted		1,475,875		$	2.94
Forfeited		(445,116	)	$	4.30
Expired		(272,764	)	$	5.15
Exercised		—		$	—
Outstanding as of December 31, 2021		2,929,472		$	4.51		7.6	$	—
Options exercisable as of December 31, 2021		1,298,540		$	5.23		5.9	$	—
Options unvested as of December 31, 2021		1,630,932		$	3.94		8.9	$	—

The weighted average grant-date fair value per share of stock options granted was $2.28 and $3.68 for the years ended December 31, 2021 and 2020, respectively.

The aggregate fair value of stock options that vested during the years ended December 31, 2021 and 2020 was $2.4 million and $2.2 million, respectively.

The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The aggregate intrinsic value of stock options exercised during the year ended December 31, 2020 was $81. No stock options were exercised during the year ended December 31, 2021.

The assumptions that the Company used to determine the fair value of the stock options granted were as follows, presented on a weighted average basis:

	Year Ended December 31,
	2021			2020
Risk-free interest rate		0.8	%		1.2	%
Expected volatility		94.0	%		81.5	%
Expected dividend yield		—			—
Expected life of options (in years)		6.5			6.8

In April 2019, the Company’s board of directors adopted the 2019 Employee Stock Purchase Plan (the “2019 ESPP”), which became effective on May 7, 2019. The 2019 ESPP is administered by the Company’s board of directors.

The total number of shares of common stock that may be issued under the 2019 ESPP was 518,918 as of December 31, 2021, of which 470,631 shares remain available for issuance. The number of shares of the Company’s common stock that have been approved to be issued under the 2019 ESPP is equal to the sum of: i) 155,106 shares; plus ii) an annual increase to be added on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2020 and continuing for each fiscal year until, and including, the fiscal year ending December 31, 2029, equal to the least of (a) 526,315 shares of common stock, (b) 1% of the number of outstanding shares of the Company’s common stock on such date, and (c) an amount determined by the Company’s board of directors. Effective January 1, 2021 and January 1, 2020, respectively, the aggregate number of shares of the Company’s common stock that may be issued under the 2019 ESPP increased, pursuant to the terms of the 2019 ESPP, by an additional 185,467 shares and 178,345 shares, equal to 1% of the Company’s then-outstanding common stock.

The following table summarizes the classifications of stock-based compensation expenses for the 2012 Plan, the 2019 Plan and the 2019 ESPP recognized in the Consolidated Statements of Operations:

	Year Ended December 31,
	2021		2020
General and administrative expense	$	1,800	$	2,057
Research and development expense		743		360
	$	2,543	$	2,417

As of December 31, 2021, total unrecognized compensation cost related to the unvested share-based awards was $3.8 million, which is expected to be recognized over a weighted average period of 2.1 years.