0001564590-20-053539 | 10-Q | XBRL Viewer

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2020	Nov. 06, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	GRAY
Entity Registrant Name	GRAYBUG VISION, INC.
Entity Central Index Key	0001534133
Entity Current Reporting Status	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		20,979,265
Entity File Number	001-39538
Entity Tax Identification Number	45-2120079
Entity Address, Address Line One	275 Shoreline Drive
Entity Address, Address Line Two	Suite 450
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94065
City Area Code	650
Local Phone Number	487-2800
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 94,968	$ 15,870
Short-term investments		20,086
Prepaid expenses and other current assets	138	315
Total current assets	95,106	36,271
Property and equipment, net	1,788	1,975
Prepaid expenses and other non-current assets	1,491	2,414
Total assets	98,385	40,660
Current liabilities:
Accounts payable	4,562	4,636
Accrued research and development	1,023	2,333
Other current liabilities	2,156	3,124
Preferred stock tranche obligation		2,158
Total current liabilities	7,741	12,251
Deferred rent, long term portion	10
Total liabilities	7,751	12,251
Commitments and contingencies (Note 6)
Convertible preferred stock		131,363
Stockholders’ Equity (Deficit):
Common stock	2
Additional paid-in capital	214,847	2,879
Accumulated deficit	(124,215)	(105,836)
Accumulated other comprehensive income		3
Total stockholders’ equity (deficit)	90,634	(102,954)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 98,385	$ 40,660

Condensed Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Condensed Statements of Operations - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating expenses:
Research and development	$ 4,757	$ 8,403	$ 15,474	$ 22,570
General and administrative	2,064	1,962	5,183	4,404
Total operating expenses	6,821	10,365	20,657	26,974
Loss from operations	(6,821)	(10,365)	(20,657)	(26,974)
Interest income	3	160	120	211
Change in fair value of preferred stock tranche obligation	2,102		2,158
Net loss	(4,716)	(10,205)	(18,379)	(26,763)
Cumulative dividends on convertible preferred stock	(2,396)	(2,048)	(7,189)	(4,633)
Net loss attributable to common stockholders	$ (7,112)	$ (12,253)	$ (25,568)	$ (31,396)
Net loss per common share—basic and diluted	$ (2.52)	$ (9.30)	$ (13.74)	$ (24.10)
Weighted-average number of shares outstanding used in computing net loss per common share—basic and diluted	2,818,349	1,317,497	1,861,229	1,302,687

Condensed Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net loss	$ (4,716)	$ (10,205)	$ (18,379)	$ (26,763)
Unrealized gain (loss) on available-for-sale securities, net of tax		7	(3)	7
Comprehensive loss	$ (4,716)	$ (10,198)	$ (18,382)	$ (26,756)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Condensed Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Initial Public Offering	Common Stock	Common Stock Initial Public Offering	Additional Paid-In Capital	Additional Paid-In Capital Initial Public Offering	Accumulated Deficit	Accumulated Other Comprehensive Income	Convertible Preferred Stock	Convertible Preferred Stock Initial Public Offering
Temporary Equity, Beginning Balance at Dec. 31, 2018									$ 78,811
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2018									80,377,096
Beginning Balance at Dec. 31, 2018	$ (66,792)				$ 2,007		$ (68,799)
Beginning Balance, Shares at Dec. 31, 2018			1,292,858
Stock issued on exercise of stock options	9				9
Stock issued on exercise of stock options, Shares			3,787
Stock-based compensation expense	156				156
Net loss	(6,295)						(6,295)
Temporary Equity, Ending Balance at Mar. 31, 2019									$ 78,811
Temporary Equity, Ending Balance, Shares at Mar. 31, 2019									80,377,096
Ending Balance at Mar. 31, 2019	(72,922)				2,172		(75,094)
Ending Balance, Shares at Mar. 31, 2019			1,296,645
Temporary Equity, Beginning Balance at Dec. 31, 2018									$ 78,811
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2018									80,377,096
Beginning Balance at Dec. 31, 2018	(66,792)				2,007		(68,799)
Beginning Balance, Shares at Dec. 31, 2018			1,292,858
Net loss	(26,763)
Changes in unrealized gains on available-for-sale securities, net of income tax	7
Temporary Equity, Ending Balance at Sep. 30, 2019									$ 131,363
Temporary Equity, Ending Balance, Shares at Sep. 30, 2019									117,809,883
Ending Balance at Sep. 30, 2019	(92,869)				2,686		(95,562)	$ 7
Ending Balance, Shares at Sep. 30, 2019			1,369,858
Temporary Equity, Beginning Balance at Mar. 31, 2019									$ 78,811
Temporary Equity, Beginning Balance, Shares at Mar. 31, 2019									80,377,096
Beginning Balance at Mar. 31, 2019	(72,922)				2,172		(75,094)
Beginning Balance, Shares at Mar. 31, 2019			1,296,645
Stock-based compensation expense	142				142
Net loss	(10,263)						(10,263)
Temporary Equity, Ending Balance at Jun. 30, 2019									$ 78,811
Temporary Equity, Ending Balance, Shares at Jun. 30, 2019									80,377,096
Ending Balance at Jun. 30, 2019	(83,043)				2,314		(85,357)
Ending Balance, Shares at Jun. 30, 2019			1,296,645
Issuance of convertible preferred stock, net of issuance costs and discount on allocation of proceeds to preferred stock tranche obligation									$ 52,552
Issuance of convertible preferred stock, net of issuance costs and discount on allocation of proceeds to preferred stock tranche obligation, Shares									37,432,787
Stock issued on exercise of stock options	122				122
Stock issued on exercise of stock options, Shares			73,213
Stock-based compensation expense	250				250
Net loss	(10,205)						(10,205)
Changes in unrealized gains on available-for-sale securities, net of income tax	7							7
Temporary Equity, Ending Balance at Sep. 30, 2019									$ 131,363
Temporary Equity, Ending Balance, Shares at Sep. 30, 2019									117,809,883
Ending Balance at Sep. 30, 2019	(92,869)				2,686		(95,562)	7
Ending Balance, Shares at Sep. 30, 2019			1,369,858
Temporary Equity, Beginning Balance at Dec. 31, 2019	$ 131,363								$ 131,363
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2019	117,809,883								117,809,883
Beginning Balance at Dec. 31, 2019	$ (102,954)				2,879		(105,836)	3
Beginning Balance, Shares at Dec. 31, 2019			1,371,467
Stock issued on exercise of stock options	11				11
Stock issued on exercise of stock options, Shares			5,446
Stock-based compensation expense	226				226
Net loss	(7,794)						(7,794)
Changes in unrealized gains on available-for-sale securities, net of income tax	(3)							(3)
Temporary Equity, Ending Balance at Mar. 31, 2020									$ 131,363
Temporary Equity, Ending Balance, Shares at Mar. 31, 2020									117,809,883
Ending Balance at Mar. 31, 2020	(110,514)				3,116		(113,630)
Ending Balance, Shares at Mar. 31, 2020			1,376,913
Temporary Equity, Beginning Balance at Dec. 31, 2019	$ 131,363								$ 131,363
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2019	117,809,883								117,809,883
Beginning Balance at Dec. 31, 2019	$ (102,954)				2,879		(105,836)	$ 3
Beginning Balance, Shares at Dec. 31, 2019			1,371,467
Net loss	(18,379)
Changes in unrealized gains on available-for-sale securities, net of income tax	$ (3)
Temporary Equity, Ending Balance, Shares at Sep. 30, 2020	0
Ending Balance at Sep. 30, 2020	$ 90,634		$ 2		214,847		(124,215)
Ending Balance, Shares at Sep. 30, 2020			20,135,515
Temporary Equity, Beginning Balance at Mar. 31, 2020									$ 131,363
Temporary Equity, Beginning Balance, Shares at Mar. 31, 2020									117,809,883
Beginning Balance at Mar. 31, 2020	(110,514)				3,116		(113,630)
Beginning Balance, Shares at Mar. 31, 2020			1,376,913
Stock issued on exercise of stock options	12				12
Stock issued on exercise of stock options, Shares			5,287
Stock-based compensation expense	214				214
Net loss	(5,869)						(5,869)
Temporary Equity, Ending Balance at Jun. 30, 2020									$ 131,363
Temporary Equity, Ending Balance, Shares at Jun. 30, 2020									117,809,883
Ending Balance at Jun. 30, 2020	(116,157)				3,342		(119,499)
Ending Balance, Shares at Jun. 30, 2020			1,382,200
Issuance of common stock upon the initial public offering, net		$ 79,529		$ 1		$ 79,528
Issuance of common stock upon initial public offering, net of issuance costs, Shares				5,625,000
Temporary Equity, Conversion of convertible preferred stock into common stock upon initial public offering										$ (131,363)
Temporary Equity, Conversion of convertible preferred stock into common stock upon initial public offering, Shares										(117,809,883)
Conversion of convertible preferred stock into common stock upon the initial public offering		$ 131,363		$ 1		$ 131,362
Conversion of convertible preferred stock into common stock upon the initial public offering, Shares				13,085,913
Stock issued on exercise of stock options	54				54
Stock issued on exercise of stock options, Shares			42,402
Stock-based compensation expense	561				561
Net loss	$ (4,716)						(4,716)
Temporary Equity, Ending Balance, Shares at Sep. 30, 2020	0
Ending Balance at Sep. 30, 2020	$ 90,634		$ 2		$ 214,847		$ (124,215)
Ending Balance, Shares at Sep. 30, 2020			20,135,515

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating activities:
Net loss	$ (18,379)	$ (26,763)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,001	548
Depreciation	284	219
Change in fair value of preferred stock tranche obligation	(2,158)
Accretion of premium and discounts on short-term investments	(17)	(25)
Changes in operating assets and liabilities:
Prepaid expenses and other current and noncurrent assets	227	1,505
Accounts payable	(1,204)	2,581
Accrued research and development	(1,310)	(20)
Other current liabilities	(747)	613
Deferred rent, long term portion	10
Net cash used in operating activities	(22,293)	(21,342)
Investing activities:
Purchases of property and equipment	(197)	(457)
Purchases of short-term investments		(18,969)
Maturity of short-term investments	20,100
Net cash provided by (used in) investing activities	19,903	(19,426)
Financing activities:
Proceeds from issuance of common stock upon initial public offering, net of underwriting discounts and commissions	83,700
Proceeds from issuance of convertible preferred stock, net of issuance costs		54,787
Proceeds from exercise of stock options	77	131
Payment of offering costs	(2,289)
Net cash provided by financing activities	81,488	54,918
Net increase in cash and cash equivalents	79,098	14,150
Cash and cash equivalents at beginning of period	15,870	12,834
Cash and cash equivalents at end of period	94,968	26,984
Supplemental disclosure of noncash items:
Deferred offering costs included in accounts payable and other current liabilities	1,837	13
Conversion of convertible preferred stock into common stock upon initial public offering	131,363
Property and equipment purchases included in accounts payable	$ 60	$ 6

Organization

9 Months Ended

Sep. 30, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization

1. Organization

Graybug Vision, Inc., the Company or Graybug, is a clinical stage biopharmaceutical company developing medicines for the treatment of diseases of the retina and optic nerve. The Company presently devotes substantially all of its resources to conducting research and development and raising capital. The Company was founded in May 2011 and maintains facilities in Redwood City, California and Baltimore, Maryland.

The Company is subject to risks common to clinical stage companies in the biopharmaceutical industry, including dependence on the clinical success of its product candidates, ability to obtain regulatory approvals of its product candidates, compliance with regulatory requirements, the need for substantial additional financing and protection of its proprietary technology.

Initial Public Offering

On September 24, 2020, the Company completed its initial public offering, or IPO, of 5,625,000 shares of its common stock at a public offering price of $16.00 per share, pursuant to the Company’s registration statement on Form S-1, which was declared effective by the Securities and Exchange Commission, or the SEC, on that date. The shares of the Company’s common stock began trading on the Nasdaq Global Market on September 25, 2020 and the IPO closed on September 29, 2020. As a result of the IPO, the Company received net proceeds of $79.5 million, after deducting underwriting discounts, commissions and offering expenses, but before giving effect to the underwriters’ subsequent exercise of their overallotment option in October 2020 (see Note 11). Prior to the completion of the IPO, all 117,809,883 shares of redeemable convertible preferred stock then outstanding were converted into 13,085,913 shares of common stock.

Reverse Stock Split

On September 18, 2020, the Company effected a 9.0058:1 reverse stock split of its issued and outstanding common stock. Upon the effectiveness of the reverse stock split, (i) all shares of outstanding common stock were adjusted; (ii) the conversion prices of the convertible preferred stock were adjusted; (iii) the number of shares of common stock for which each outstanding option and warrant to purchase common stock is exercisable were adjusted; and (iv) the exercise price of each outstanding option and warrant to purchase common stock was adjusted. All of the outstanding common stock share numbers (including shares of common stock subject to the Company’s options, warrants and as converted for the outstanding convertible preferred stock), share prices, exercise prices and per share amounts contained in the condensed financial statements have been retroactively adjusted in the condensed financial statements to reflect this reverse stock split for all periods presented. The par value per share and the authorized number of shares of common stock were not adjusted as a result of the reverse stock split.

Going Concern Considerations

The Company incurred losses from operations and had negative cash flows from operating activities for the three and nine months ended September 30, 2020 and 2019, and the Company’s accumulated deficit at September 30, 2020 is $124.2 million. Prior to the IPO, the Company historically funded its operations through the issuance of shares of its convertible preferred stock. The Company’s current operating plan indicates it will continue to incur losses from operations and generate negative cash flows from operating activities, given ongoing expenditures related to extensive research and development and the Company’s lack of revenue generating activities at this point in the Company’s life cycle. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

As of April 21, 2020, the issuance date of the Company’s audited financial statements for the year ended December 31, 2019, the Company concluded that there was substantial doubt about its ability to continue as a going concern for one year after the date that those financial statements were issued. Subsequent to the issuance of those financial statements, the Company received proceeds of $79.5 million, net of the underwriters’ discounts, from the IPO in September 2020. Additionally, in October 2020 the Company received additional proceeds of $12.6 million from the underwriters’ exercise of their option to purchase additional shares of the Company’s common stock (see Note 11). Accordingly, as of the issuance date of these unaudited condensed financial statements, the Company expects its cash and cash equivalents of $95.0 million as of September 30, 2020, will be sufficient to fund its operating expenses and capital expenditure requirements for at least 12 months beyond the date of issuance of these unaudited condensed financial statements. The future viability of the Company beyond that point is dependent on its ability to raise additional capital to finance its operations.

The Company may seek to raise additional funds in order to further advance its research and development programs, operate its business and meet its obligations as they come due. The Company is pursuing financing alternatives, similar to what the Company has previously executed, which include equity financing. However, financing may not be available to the Company in the necessary time frame, in the amounts that the Company requires, on terms that are acceptable to the Company, or at all. If the Company is unable to raise the necessary funds when needed or reduce spending on currently planned activities, it may not be able to continue the development of its products or the Company could be required to delay, scale back, or eliminate some or all of its research and development programs and other operations and will materially harm its business, financial position and results of operations.

Coronavirus Outbreak

In March 2020 the World Health Organization declared the global novel coronavirus disease 2019, or COVID-19, outbreak a pandemic. As of September 30, 2020, the Company’s operations have not been significantly impacted by the COVID-19 outbreak. However, the Company cannot at this time predict the specific extent, duration, or full impact that the COVID-19 outbreak will have on its financial condition and operations, including ongoing and planned clinical trials. The impact of the COVID-19 outbreak on the financial performance of the Company will depend on future developments, including the duration and spread of the outbreak and related governmental advisories and restrictions. These developments and the impact of COVID-19 on the financial markets and the overall economy are highly uncertain and cannot be predicted. If the financial markets and/or the overall economy are impacted for an extended period, the Company’s results may be materially adversely affected.

In March 2020, the Families First Coronavirus Response Act, or FFCR Act, and the Coronavirus Aid, Relief and Economic Security Act, or CARES Act, were signed into law in response to the COVID-19 pandemic. The FFCR Act and CARES Act include provisions related to refundable payroll tax credits, deferment of employer side social security payments, and retroactively and temporarily (for taxable years beginning before January 1, 2021) suspending the application of the 80%-of-income limitation on the use of net operating losses, which was enacted as part of the Tax Cuts and Jobs Act of 2017. The CARES Act also provides that net operating losses arising in any taxable year beginning after December 31, 2017, and before January 1, 2021 are generally eligible to be carried back up to five years.

In June 2020, Assembly Bill 85, or A.B. 85, was signed into California law. A.B. 85 provides for a three-year suspension of the use of net operating losses for medium and large businesses and a three-year cap on the use of business incentive tax credits to offset no more than $5.0 million of tax per year. A.B. 85 suspends the use of net operating losses for taxable years 2020, 2021 and 2022 for certain taxpayers with taxable income of $1.0 million or more. The carryover period for any net operating losses that are suspended under this provision will be extended. A.B. 85 also requires that business incentive tax credits including carryovers may not reduce the applicable tax by more than $5.0 million for taxable years 2020, 2021 and 2022.

The enactment of the FFCR Act, CARES Act and A.B. 85 did not result in any material adjustments to the Company’s income tax provision for the nine months ended September 30, 2020 or to the Company’s net deferred tax assets as of September 30, 2020. Given the Company’s history of losses, the Company does not expect the provisions of the FFCR Act, CARES Act and A.B. 85 to have a material impact on the Company’s annual effective tax rate or condensed financial statements in 2020; however, the Company will continue to evaluate the impact of tax legislation and will update its disclosures as additional information and interpretive guidance becomes available.

Fair Value Measurements

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements

The Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible. The Company determines fair value based on assumptions that market participants would use in pricing an asset or liability in the principal or most advantageous market. When considering market participant assumptions in fair value measurements, the following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels:

•

Level 1: Observable inputs such as unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date.

•

Level 2: Inputs (other than quoted prices included in Level 1) that are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active.

•

Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values (in thousands):

	September 30, 2020
	Level 1		Level 2		Level 3		Total
Current assets:
Cash equivalents:
Money market funds	$	94,355	$	—	$	—	$	94,355
Total assets measured at fair value	$	94,355	$	—	$	—	$	94,355

	December 31, 2019
	Level 1		Level 2		Level 3		Total
Current assets:
Cash equivalents:
Money market funds	$	12,859	$	—	$	—	$	12,859
Corporate debt securities		—		500		—		500
Total cash equivalents		12,859		500		—		13,359
Short-term investments:
Government agency bonds		—		2,750		—		2,750
Corporate debt securities		—		11,349		—		11,349
Commercial paper		—		5,987		—		5,987
Total short-term investments		—		20,086		—		20,086
Total assets measured at fair value	$	12,859	$	20,586	$	—	$	33,445
Current liabilities:
Preferred stock tranche obligation	$	—	$	—	$	2,158	$	2,158
Total liabilities measured at fair value	$	—	$	—	$	2,158	$	2,158

The following tables present information as to cost, unrealized gains and losses and fair value determination of the Company’s financial assets measured at fair value on a recurring basis (in thousands):

	September 30, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses		Aggregate Fair Value
Current assets:
Cash equivalents:
Money market funds	$	94,355	$	—	$	—	$	94,355
Total assets measured at fair value	$	94,355	$	—	$	—	$	94,355

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
Current assets:
Cash equivalents:
Money market funds	$	12,859	$	—	$	—		$	12,859
Corporate debt securities		500		—		—			500
Total cash equivalents		13,359		—		—			13,359
Short-term investments:
Government agency bonds		2,750		—		—			2,750
Corporate debt securities		11,348		2		(1	)		11,349
Commercial paper		5,985		2		—			5,987
Total short-term investments		20,083		4		(1	)		20,086
Total assets measured at fair value	$	33,442	$	4	$	(1	)	$	33,445

Money market funds are highly liquid investments which are actively traded. The pricing information on the Company’s money market funds are based on quoted prices in active markets for identical securities. This approach results in the classification of these securities as Level 1 of the fair value hierarchy.

The fair value of short-term investments is determined from market pricing and other observable market inputs for similar securities obtained from various third-party data providers. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities; issuer credit spreads; benchmark securities; prepayment/default projections based on historical data; and other observable inputs. This approach results in the classification of these securities as Level 2 of the fair value hierarchy.

In connection with the Company’s convertible preferred stock financing in July 2019, certain investors were granted an option to purchase additional shares contingent upon delivery to them of certain clinical trial results (see Note 7). In September 2020, the Board and these investors amended the stock purchase agreement such that the option to purchase additional shares would no longer be exercisable and would expire upon the effectiveness of the Company’s Prospectus. As a result, the Preferred Stock Tranche Obligation was remeasured as of the date of the amendment and adjusted to its fair value at that time which was deemed to be immaterial. The Preferred Stock Tranche Obligation was measured at fair value at each reporting period until its expiration on September 24, 2020 using an option pricing valuation methodology. Due to the low probability of the Preferred Stock Tranche Obligation being settled, the fair value immediately prior to the IPO was immaterial.

The fair value of the Preferred Stock Tranche Obligation includes inputs not observable in the market and thus represents a Level 3 measurement. The option methodology utilized requires inputs based on certain subjective assumptions, including (a) expected stock price volatility, (b) calculation of an expected term, (c) a risk-free interest rate, and (d) expected dividends. This approach results in the classification of this security as Level 3 of the fair value hierarchy. The assumptions utilized to value the preferred stock tranche obligation as of December 31, 2019 were (a) expected stock price volatility of 30%; (b) expected term of 0.7 years: (c) a risk-free interest rate of 1.6%; and (d) an expectation of no dividends. The change in the fair value for the three-month and nine-month periods ended September 30, 2020 was $2.1 million and $2.2 million, respectively.

The following table provides a reconciliation of Level 3 liabilities measured at fair value on a recurring basis using significant unobservable inputs (in thousands):

	Amount
Fair value as of January 1, 2020	$	2,158
Change in fair value and expiration of the preferred stock tranche obligation		(2,158	)
Balance as of September 30, 2020	$	—

There were no transfers between Levels 1, 2 or 3 for the periods presented.

Convertible Preferred Stock and Stockholders’ Equity (Deficit)

9 Months Ended

Sep. 30, 2020

Temporary Equity Disclosure [Abstract]

Convertible Preferred Stock and Stockholders’ Equity (Deficit)

7. Convertible Preferred Stock and Stockholders’ Equity (Deficit)

The following table summarizes outstanding Convertible Preferred Stock as of December 31, 2019 (in thousands, except share amounts):

	Shares Authorized		Shares Outstanding		Net Carrying Value		Liquidation Preference
Series A		2,280,000		2,280,000	$	2,280	$	2,280
Series A-2		2,018,561		2,018,561		1,605		1,740
Series B		76,078,535		76,078,535		74,926		87,729
Series C		61,773,000		37,432,787		52,552		56,843
Total		142,150,096		117,809,883	$	131,363	$	148,592

In July 2019, the Company authorized the sale of up to 61,773,000 shares of its Series C Convertible Preferred Stock, or Series C, at a price of $1.4693 per share, or Series C Financing. In July and August 2019, the Company issued 37,432,787 shares of Series C for aggregate gross proceeds of $55.0 million. In connection with this financing, certain purchasers of the Series C had the option to purchase up to an additional 17,014,902 shares of Series C at a price per share of $1.4693 for a period of up to 30 days after the Company notified them of the three-month readout from the Phase 2a clinical trial of GB-102 in patients with macular edema secondary to diabetic macular edema and retinal vein occlusion, or the Preferred Stock Tranche Obligation. The Company concluded that the Preferred Stock Tranche Obligation met the definition of a freestanding financial instrument, as the rights were legally detachable and separately exercisable from the Series C. Therefore, the Company allocated the proceeds received from the issuance of shares under the Series C Preferred Stock Purchase Agreement between the Preferred Stock Tranche Obligation and the Series C. The fair value of the Preferred Stock Tranche Obligation of $2.2 million on issuance was allocated from the $55.0 million proceeds of the Series C Financing and is classified as a current liability on the balance sheet as of December 31, 2019 as the Series C would become redeemable upon a deemed liquidation event, the occurrence of which was not within the Company’s control.

In September 2020, the board of directors and the Series C investors amended the Series C stock purchase agreement such that the Preferred Stock Tranche Obligation was no longer exercisable and expired upon the effectiveness of the Prospectus. As a result, the liability for the Preferred Stock Tranche Obligation was permanently eliminated as of September 30, 2020.

Prior to the completion of the IPO on September 24, 2020, all of the outstanding shares of Convertible Preferred Stock automatically converted into 13,085,913 shares of common stock. Subsequent to the closing of the IPO on September 29, 2020, there were no shares of Convertible Preferred Stock outstanding.

Stock-Based Compensation

9 Months Ended

Sep. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

8. Stock-Based Compensation

2020 Equity Incentive Plan

In August 2020, the Company’s board of directors and stockholders adopted the Company’s 2020 Equity Incentive Plan, or the 2020 Plan, that became effective in connection with the IPO, and serves as the successor to the Company’s 2015 Stock Incentive Plan, or the 2015 Plan. The Company’s 2020 Plan authorizes the award of stock options, restricted stock awards, or RSAs, stock appreciation rights, or SARs, restricted stock units, or RSUs, performance awards and stock bonus awards. The Company initially reserved 1,850,000 shares of its common stock, plus any reserved shares not issued or subject to outstanding grants under the 2015 Plan on the effective date of the 2020 Plan, for issuance pursuant to awards granted under the 2020 Plan. The aggregate number of shares reserved for sale under the 2020 Plan will increase automatically on each January 1st of 2021 through 2030 by the number of shares equal to the lesser of 5% of the aggregate number of outstanding shares of the Company’s common stock as of the immediately preceding December 31, or a number as may be determined by the Company’s board of directors.

In conjunction with adopting the 2020 Plan, the Company may not grant any additional stock-based awards under the 2015 Plan, and any shares available for issuance under the 2015 Plan were added to the shares reserved under the 2020 Plan. The 2015 Plan will continue to govern outstanding stock-based awards granted thereunder. As of September 30, 2020, there were 1,826,374 shares available for issuance under the 2020 Plan.

2020 Employee Stock Purchase Plan

In August 2020 the Company’s board of directors and stockholders adopted the Company’s 2020 Employee Stock Purchase Plan, or the ESPP, that became effective in connection with the IPO, in order to enable eligible employees to purchase shares of the Company’s common stock with accumulated payroll deductions. The Company’s ESPP is intended to qualify under Section 423 of the Internal Revenue Code. The Company has initially reserved 210,000 shares of its common stock for sale under the ESPP. The aggregate number of shares reserved for sale under the Company’s ESPP will increase automatically on January 1st of each of the first ten calendar years after the first offering date under the ESPP by the number of shares equal to the lesser of 1% of the total outstanding shares of the Company’s common stock as of the immediately preceding December 31, or a number of shares as may be determined by the Company’s board of directors in any particular year. The aggregate number of shares issued over the term of the ESPP, subject to stock-splits, recapitalizations or similar events, may not exceed 2,100,000 shares of the Company’s common stock.

Stock-Based Compensation Expense

Stock-based compensation expense recognized for options granted was as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Research and development	$	105	$	46	$	245	$	146
General and administrative		456		204		756		402
Total stock-based compensation expense	$	561	$	250	$	1,001	$	548

As of September 30, 2020, the total unrecognized stock-based compensation expense related to outstanding unvested stock options that are expected to vest was $7.6 million, which the Company expects to recognize over an estimated weighted-average term of 3.3 years.

Net Loss Per Share Attributable to Common Stockholders

9 Months Ended

Sep. 30, 2020

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

10. Net Loss Per Share Attributable to Common Stockholders

Basic and diluted net loss per common share is calculated as follows (in thousands except share and per share amounts):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
Net loss	$	(4,716	)	$	(10,205	)	$	(18,379	)	$	(26,763	)
Cumulative dividends on convertible preferred stock		(2,396	)		(2,048	)		(7,189	)		(4,633	)
Net loss attributable to common stockholders	$	(7,112	)	$	(12,253	)	$	(25,568	)	$	(31,396	)
Net loss per common share—basic and diluted	$	(2.52	)	$	(9.30	)	$	(13.74	)	$	(24.10	)
Weighted-average number of shares used in computing net loss per common share—basic and diluted		2,818,349			1,317,497			1,861,229			1,302,687

The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share due to their anti-dilutive effect:

	As of September 30,
	2020		2019
Convertible preferred stock		—		117,809,883
Stock options to purchase common stock		2,615,892		1,560,826
Warrants to purchase common stock		27,759		—
Restricted stock awards		80,000		—

Under the Series C Financing, up to 17,014,902 shares of convertible preferred stock could have been contingently issued upon achievement of certain development milestones. However, in September 2020, the board of directors and the Series C investors amended the Series C stock purchase agreement such that the Preferred Stock Tranche Obligation was no longer exercisable and expired upon the effectiveness of the Prospectus.

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis

	September 30, 2020
	Level 1		Level 2		Level 3		Total
Current assets:
Cash equivalents:
Money market funds	$	94,355	$	—	$	—	$	94,355
Total assets measured at fair value	$	94,355	$	—	$	—	$	94,355

	December 31, 2019
	Level 1		Level 2		Level 3		Total
Current assets:
Cash equivalents:
Money market funds	$	12,859	$	—	$	—	$	12,859
Corporate debt securities		—		500		—		500
Total cash equivalents		12,859		500		—		13,359
Short-term investments:
Government agency bonds		—		2,750		—		2,750
Corporate debt securities		—		11,349		—		11,349
Commercial paper		—		5,987		—		5,987
Total short-term investments		—		20,086		—		20,086
Total assets measured at fair value	$	12,859	$	20,586	$	—	$	33,445
Current liabilities:
Preferred stock tranche obligation	$	—	$	—	$	2,158	$	2,158
Total liabilities measured at fair value	$	—	$	—	$	2,158	$	2,158

Summary of Company's Financial Assets Measured at Fair Value

	September 30, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses		Aggregate Fair Value
Current assets:
Cash equivalents:
Money market funds	$	94,355	$	—	$	—	$	94,355
Total assets measured at fair value	$	94,355	$	—	$	—	$	94,355

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
Current assets:
Cash equivalents:
Money market funds	$	12,859	$	—	$	—		$	12,859
Corporate debt securities		500		—		—			500
Total cash equivalents		13,359		—		—			13,359
Short-term investments:
Government agency bonds		2,750		—		—			2,750
Corporate debt securities		11,348		2		(1	)		11,349
Commercial paper		5,985		2		—			5,987
Total short-term investments		20,083		4		(1	)		20,086
Total assets measured at fair value	$	33,442	$	4	$	(1	)	$	33,445

Summary of Reconciliation of Level 3 Liabilities Measured at Fair Value

The following table provides a reconciliation of Level 3 liabilities measured at fair value on a recurring basis using significant unobservable inputs (in thousands):

	Amount
Fair value as of January 1, 2020	$	2,158
Change in fair value and expiration of the preferred stock tranche obligation		(2,158	)
Balance as of September 30, 2020	$	—

Net Loss Per Share Attributable to Common Stockholders (Tables)

9 Months Ended

Sep. 30, 2020

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss Per Common Share

Basic and diluted net loss per common share is calculated as follows (in thousands except share and per share amounts):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
Net loss	$	(4,716	)	$	(10,205	)	$	(18,379	)	$	(26,763	)
Cumulative dividends on convertible preferred stock		(2,396	)		(2,048	)		(7,189	)		(4,633	)
Net loss attributable to common stockholders	$	(7,112	)	$	(12,253	)	$	(25,568	)	$	(31,396	)
Net loss per common share—basic and diluted	$	(2.52	)	$	(9.30	)	$	(13.74	)	$	(24.10	)
Weighted-average number of shares used in computing net loss per common share—basic and diluted		2,818,349			1,317,497			1,861,229			1,302,687

Schedule of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share

The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share due to their anti-dilutive effect:

	As of September 30,
	2020		2019
Convertible preferred stock		—		117,809,883
Stock options to purchase common stock		2,615,892		1,560,826
Warrants to purchase common stock		27,759		—
Restricted stock awards		80,000		—

Organization - Additional Information (Details) $ / shares in Units, $ in Thousands			1 Months Ended			3 Months Ended	9 Months Ended
	Sep. 24, 2020 USD ($) $ / shares shares	Sep. 18, 2020	Oct. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Mar. 31, 2020	Sep. 30, 2020 USD ($) shares	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Net proceeds from shares issued							$ 83,700
Reverse stock split		0.111039552
Reverse stock split, description							On September 18, 2020, the Company effected a 9.0058:1 reverse stock split of its issued and outstanding common stock. Upon the effectiveness of the reverse stock split, (i) all shares of outstanding common stock were adjusted; (ii) the conversion prices of the convertible preferred stock were adjusted; (iii) the number of shares of common stock for which each outstanding option and warrant to purchase common stock is exercisable were adjusted; and (iv) the exercise price of each outstanding option and warrant to purchase common stock was adjusted. All of the outstanding common stock share numbers (including shares of common stock subject to the Company’s options, warrants and as converted for the outstanding convertible preferred stock), share prices, exercise prices and per share amounts contained in the condensed financial statements have been retroactively adjusted in the condensed financial statements to reflect this reverse stock split for all periods presented. The par value per share and the authorized number of shares of common stock were not adjusted as a result of the reverse stock split.
Accumulated deficit				$ 124,215		$ 124,215	$ 124,215	$ 105,836
Substantial doubt about going concern, within one year							true
Net proceeds from initial public offering				79,500
Cash and cash equivalents				$ 94,968		$ 94,968	$ 94,968	$ 15,870
Tax Cuts and Jobs Act of 2017, percentage of income limitation on use of net operating losses					80.00%
Income taxes receivable, net operating loss term, CARES Act					5 years
Income taxes receivable, net operating loss, CARES Act Relief description							In March 2020, the Families First Coronavirus Response Act, or FFCR Act, and the Coronavirus Aid, Relief and Economic Security Act, or CARES Act, were signed into law in response to the COVID-19 pandemic. The FFCR Act and CARES Act include provisions related to refundable payroll tax credits, deferment of employer side social security payments, and retroactively and temporarily (for taxable years beginning before January 1, 2021) suspending the application of the 80%-of-income limitation on the use of net operating losses, which was enacted as part of the Tax Cuts and Jobs Act of 2017. The CARES Act also provides that net operating losses arising in any taxable year beginning after December 31, 2017, and before January 1, 2021 are generally eligible to be carried back up to five years. In June 2020, Assembly Bill 85, or A.B. 85, was signed into California law. A.B. 85 provides for a three-year suspension of the use of net operating losses for medium and large businesses and a three-year cap on the use of business incentive tax credits to offset no more than $5.0 million of tax per year. A.B. 85 suspends the use of net operating losses for taxable years 2020, 2021 and 2022 for certain taxpayers with taxable income of $1.0 million or more. The carryover period for any net operating losses that are suspended under this provision will be extended. A.B. 85 also requires that business incentive tax credits including carryovers may not reduce the applicable tax by more than $5.0 million for taxable years 2020, 2021 and 2022.
Initial Public Offering \| Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Issuance of common stock upon initial public offering, net of issuance costs, Shares \| shares	5,625,000					5,625,000
Shares issued and sold, price per share \| $ / shares	$ 16.00
Net proceeds from shares issued	$ 79,500
Outstanding redeemable convertible preferred stock converted to common stock \| shares	13,085,913
Conversion of convertible preferred stock into common stock upon initial public offering \| shares	117,809,883
Underwriters’ Option \| Subsequent Event
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Net proceeds from initial public offering			$ 12,600

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Accounts payable, related parties	$ 56,000		$ 56,000		$ 104,000
General and Administrative
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Related party transaction, costs incurred	$ 212,000	$ 82,000	$ 657,000	$ 82,000
Accounting Standards Update 2018-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted	true		true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020		Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect	true		true

- Definition

Indicates (true false) whether accounting standards update was adopted.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Section 65
-Paragraph 2
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 926
-SubTopic 20
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-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120154821&loc=SL120154904-197079

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 10
-Section 65
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121646688&loc=SL120320025-210437

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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+ Details

- Definition

Date accounting standards update was adopted, in CCYY-MM-DD format.

+ References

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+ Details

Fair Value Measurements - Summary of Company 's Financial Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Aggregate Fair Value		$ 13,359
Total asset measured at fair value, Aggregate Fair Value	$ 94,355	33,445
Total short-term investments, Aggregate Fair Value		20,086
Fair Value, Recurring
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost		13,359
Total cash equivalents, Aggregate Fair Value		13,359
Total asset measured at fair value, Amortized Cost	94,355	33,442
Total asset measured at fair value, Unrealized Gains		4
Total asset measured at fair value, Unrealized Losses		(1)
Total asset measured at fair value, Aggregate Fair Value	94,355	33,445
Total short-term investments, Amortized Cost		20,083
Total short-term investments, Unrealized Gains		4
Total short-term investments, Unrealized Losses		(1)
Total short-term investments, Aggregate Fair Value		20,086
Fair Value, Recurring \| Money Market Funds
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost	94,355	12,859
Total cash equivalents, Aggregate Fair Value	$ 94,355	12,859
Fair Value, Recurring \| Corporate Debt Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost		500
Total cash equivalents, Aggregate Fair Value		500
Total short-term investments, Amortized Cost		11,348
Total short-term investments, Unrealized Gains		2
Total short-term investments, Unrealized Losses		(1)
Total short-term investments, Aggregate Fair Value		11,349
Fair Value, Recurring \| Government Agency Bonds
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total short-term investments, Amortized Cost		2,750
Total short-term investments, Aggregate Fair Value		2,750
Fair Value, Recurring \| Commercial Paper
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total short-term investments, Amortized Cost		5,985
Total short-term investments, Unrealized Gains		2
Total short-term investments, Aggregate Fair Value		$ 5,987

Fair Value Measurements - Additional Information (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value assets, level 1 to level 2 transfers, amount	$ 0	$ 0
Fair value assets, level 2 to level 1 transfers, amount	0	0
Fair value assets, transfers into level 3		0
Fair value liabilities, level 1 to Level 2 transfers amount	0	0
Fair value liabilities, level 2 to Level 1 transfers amount	0	0
Fair value liabilities, transfers into level 3		0
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt Instrument, expected term measurement input			8 months 12 days
Level 3 \| Fair Value, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in fair value	$ 2,100,000	$ 2,200,000
Level 3 \| Measurement Input, Stock Price Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt instrument measurement input			30
Level 3 \| Measurement Input, Risk Free Interest Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt instrument measurement input			1.6
Level 3 \| Measurement Input, Expected Dividend Payment
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt instrument measurement input			0

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Summary of Outstanding Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Jul. 31, 2019
Temporary Equity [Line Items]
Shares Authorized		142,150,096
Shares Outstanding	0	117,809,883
Net Carrying Value		$ 131,363
Liquidation Preference		$ 148,592
Series A
Temporary Equity [Line Items]
Shares Authorized		2,280,000
Shares Outstanding		2,280,000
Net Carrying Value		$ 2,280
Liquidation Preference		$ 2,280
Series A-2
Temporary Equity [Line Items]
Shares Authorized		2,018,561
Shares Outstanding		2,018,561
Net Carrying Value		$ 1,605
Liquidation Preference		$ 1,740
Series B
Temporary Equity [Line Items]
Shares Authorized		76,078,535
Shares Outstanding		76,078,535
Net Carrying Value		$ 74,926
Liquidation Preference		$ 87,729
Series C
Temporary Equity [Line Items]
Shares Authorized		61,773,000	61,773,000
Shares Outstanding		37,432,787
Net Carrying Value		$ 52,552
Liquidation Preference		$ 56,843

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	2 Months Ended	9 Months Ended
	Sep. 24, 2020	Jul. 31, 2019	Aug. 31, 2019	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019
Temporary Equity [Line Items]
Convertible preferred stock authorized to sell						142,150,096
Proceeds from issuance of convertible preferred stock, net of issuance costs				$ 54,787
Shares Outstanding					0	117,809,883
Initial Public Offering
Temporary Equity [Line Items]
Convertible preferred stock converted into common stock	13,085,913
Series C Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock authorized to sell		61,773,000				61,773,000
Convertible preferred stock, price per share		$ 1.4693
Convertible preferred stock, shares issued			37,432,787
Proceeds from issuance of convertible preferred stock, net of issuance costs			$ 55,000
Convertible preferred stock, price per share		$ 1.4693
Shares Outstanding						37,432,787
Series C Convertible Preferred Stock \| Current Liability
Temporary Equity [Line Items]
Fair value of preferred stock tranche obligation						$ 2,200
Series C Convertible Preferred Stock \| Maximum
Temporary Equity [Line Items]
Convertible preferred stock option to purchase additional shares		17,014,902		17,014,902
Convertible preferred stock option to purchase additional shares after notified, period		30 days

Net Loss Per Share Attributable to Common Stockholders - Schedule of Basic and Diluted Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net loss	$ (4,716)	$ (5,869)	$ (7,794)	$ (10,205)	$ (10,263)	$ (6,295)	$ (18,379)	$ (26,763)
Cumulative dividends on convertible preferred stock	(2,396)			(2,048)			(7,189)	(4,633)
Net loss attributable to common stockholders	$ (7,112)			$ (12,253)			$ (25,568)	$ (31,396)
Net loss per common share—basic and diluted	$ (2.52)			$ (9.30)			$ (13.74)	$ (24.10)
Weighted-average number of shares outstanding used in computing net loss per common share—basic and diluted	2,818,349			1,317,497			1,861,229	1,302,687

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

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+ Details

Condensed Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) (Parenthetical) $ in Thousands	3 Months Ended
	Sep. 30, 2019 USD ($)
Series C Convertible Preferred Stock
Offering and Issuance costs	$ 217
Discount on allocation of proceeds to preferred stock tranche obligation	$ 2,230

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements contained in this Quarterly Report on Form 10-Q have been prepared in accordance with the rules and regulations of the SEC and, therefore, certain information and disclosures normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, have been omitted. In the opinion of management, the information reflects all adjustments necessary to make the results of operations for the interim periods a fair statement of such operations. All such adjustments are of a normal recurring nature. Interim results are not necessarily indicative of results for the full year. The condensed balance sheet at December 31, 2019 has been derived from the audited financial statements at that date, but does not include all information and footnotes required by GAAP for complete financial statements. These unaudited condensed financial statements should be read in conjunction with the Company’s audited financial statements included in the Prospectus.
Related Party Transactions	Related Party Transactions In August 2019, the Company engaged a consulting firm managed by the then acting chief financial officer of the Company for professional services related to accounting, finance and other administrative functions. For the three months ended September 30, 2020 and 2019, the costs incurred under this arrangement totaled $212,000 and $82,000 and for the nine months ended September 30, 2020 and 2019, the costs totaled $657,000 and $82,000, respectively. These costs were recorded as general and administrative expense in the accompanying condensed statements of operations. As of September 30, 2020, amounts owed under this arrangement totaled $56,000 and are included in accounts payable in the accompanying condensed balance sheet. As of December 31, 2019 and September 30, 2020, amounts owed under this arrangement totaled $104,000 and $56,000, respectively, and are included in accounts payable in the accompanying condensed balance sheets.

Prepaid Expenses and Other Non-Current Assets - Schedule of Prepaid Expenses and Other Non-Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Prepaid Expense And Other Assets Noncurrent [Abstract]
Prepaid clinical and research expenses	$ 1,462	$ 1,462
Deferred offering costs		894
Deposits	29	58
Total prepaid expenses and other non-current assets	$ 1,491	$ 2,414

Other Current Liabilities - Schedule of Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Other Liabilities Current [Abstract]
Salaries and benefits	$ 1,562	$ 2,044
Deferred rent	35
Other	559	1,080
Total other current liabilities	$ 2,156	$ 3,124

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Loss Contingencies [Line Items]
Rent expense	$ 192,000	$ 176,000	$ 544,000	$ 520,000
Redwood City, California
Loss Contingencies [Line Items]
Operating lease, term			2021-08
Baltimore, Maryland
Loss Contingencies [Line Items]
Operating lease, term			2023-06

Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash equivalents		$ 13,359
Assets measured at fair value	$ 94,355	33,445
Short-term investments		20,086
Current liabilities:
Liabilities measured at fair value		2,158
Money Market Funds
Current assets:
Cash equivalents	94,355	12,859
Level 1
Current assets:
Cash equivalents		12,859
Assets measured at fair value	94,355	12,859
Level 1 \| Money Market Funds
Current assets:
Cash equivalents	$ 94,355	12,859
Level 2
Current assets:
Cash equivalents		500
Assets measured at fair value		20,586
Short-term investments		20,086
Level 3
Current liabilities:
Liabilities measured at fair value		2,158
Corporate Debt Securities
Current assets:
Cash equivalents		500
Short-term investments		11,349
Corporate Debt Securities \| Level 2
Current assets:
Cash equivalents		500
Short-term investments		11,349
Government Agency Bonds
Current assets:
Short-term investments		2,750
Government Agency Bonds \| Level 2
Current assets:
Short-term investments		2,750
Commercial Paper
Current assets:
Short-term investments		5,987
Commercial Paper \| Level 2
Current assets:
Short-term investments		5,987
Preferred Stock Tranche Obligation
Current liabilities:
Liabilities measured at fair value		2,158
Preferred Stock Tranche Obligation \| Level 3
Current liabilities:
Liabilities measured at fair value		$ 2,158

Fair Value Measurements - Reconciliation of Level 3 Liabilities Measured at Fair Value (Details) - Fair Value, Recurring - Level 3 $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value as of January 1, 2020	$ 2,158
Change in fair value and expiration of the preferred stock tranche obligation	$ (2,158)

Commitments and Contingencies - Schedule of Future Minimum Lease Payments (Details) $ in Thousands	Sep. 30, 2020 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2020 (remaining three months)	$ 196
2021	660
2022	405
2023	205
Total future minimum lease payments	$ 1,466

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Aug. 31, 2020	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized stock-based compensation expenses related to outstanding unvested stock options		$ 7.6
Total unrecognized stock-based compensation expenses related to outstanding unvested stock options weighted-average term of recognition		3 years 3 months 18 days
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares reserved for future issuance	1,850,000	1,826,374
Percentage of aggregate number of shares of common stock outstanding on last day of preceding year added to plan	5.00%
Number of additional awards grant	0
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares reserved for future issuance	210,000
Percentage of aggregate number of shares of common stock outstanding on last day of preceding year added to plan	1.00%
Aggregate number of shares issued over the term of the ESPP		2,100,000

Subsequent Events - Additional Information (Details) - Initial Public Offering - USD ($) $ / shares in Units, $ in Millions		1 Months Ended
	Sep. 24, 2020	Oct. 31, 2020
Subsequent Event [Line Items]
Number of days, underwriters option to purchase shares	30 days
Maximum
Subsequent Event [Line Items]
Underwriters option to purchase additional shares	843,750
Common Stock
Subsequent Event [Line Items]
Shares issued and sold, price per share	$ 16.00
Subsequent Event
Subsequent Event [Line Items]
Stock issued to underwriters upon exercise of option to purchase additional shares		843,750
Net proceeds received after deducting underwriting discounts and commissions		$ 12.6