0001564590-21-011305 | 10-K | XBRL Viewer

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2020	Feb. 26, 2021	Sep. 25, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	GRAY
Entity Registrant Name	GRAYBUG VISION, INC.
Entity Central Index Key	0001534133
Entity Current Reporting Status	Yes
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		21,043,984
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 Annual Report	true
Document Transition Report	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 120,200,000
ICFR Auditor Attestation Flag	false
Documents Incorporated by Reference	Portions of the registrant’s Definitive Proxy Statement relating to the 2021 Annual Meeting of Shareholders are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein. The Definitive Proxy Statement will be filed within 120 days of the Registrant’s fiscal year ended December 31, 2020. Except with respect to information specifically incorporated by reference in this Form 10-K, the Proxy Statement is not deemed to be filed as part of this Form 10-K.

Balance Sheets (Unaudited) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 33,418	$ 15,870
Short-term investments	61,615	20,086
Prepaid expenses and other current assets	4,207	315
Total current assets	99,240	36,271
Property and equipment, net	1,946	1,975
Prepaid expenses and other non-current assets	608	2,414
Total assets	101,794	40,660
Current liabilities:
Accounts payable	2,513	4,636
Accrued research and development	1,356	2,333
Other current liabilities	3,128	3,124
Preferred stock tranche obligation		2,158
Total current liabilities	6,997	12,251
Deferred rent, long term portion	11
Total liabilities	7,008	12,251
Commitments and contingencies (Note 5)
Convertible preferred stock, $0.0001 par value; 142,150,096 shares authorized as of December 31, 2019, 0 and 117,809,883 shares issued and outstanding as of December 31, 2020 and 2019, respectively; aggregate liquidation value of $0 and $148,592 as of December 31, 2020 and 2019, respectively		131,363
Stockholders’ Equity (Deficit):
Preferred stock, $0.0001 par value; 10,000,000 authorized, no shares outstanding as of December 31, 2020 and 2019, respectively
Common stock, $0.0001 par value; 500,000,000 and 188,000,000 shares authorized, 20,979,265 and 1,371,467 shares issued and outstanding as of December 31, 2020 and 2019, respectively	2
Additional paid-in capital	228,155	2,879
Accumulated deficit	(133,367)	(105,836)
Accumulated other comprehensive (loss) income	(4)	3
Total stockholders’ equity (deficit)	94,786	(102,954)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 101,794	$ 40,660

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
Statements of Operations - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 20,962	$ 30,580
General and administrative	8,870	6,922
Total operating expenses	29,832	37,502
Loss from operations	(29,832)	(37,502)
Interest income	143	393
Change in fair value of preferred stock tranche obligation	2,158	72
Net loss	(27,531)	(37,037)
Cumulative dividends on convertible preferred stock	(7,189)	(7,055)
Net loss attributable to common stockholders	$ (34,720)	$ (44,092)
Net loss per common share—basic and diluted	$ (5.25)	$ (33.41)
Weighted-average number of shares outstanding used in computing net loss per common share—basic and diluted	6,618,445	1,319,912

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - 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 (loss)	Convertible Preferred Stock	Convertible Preferred Stock Initial Public Offering
Beginning Balance at Dec. 31, 2018	$ (66,792)				$ 2,007		$ (68,799)
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2018									80,377,096
Temporary Equity, Beginning Balance at Dec. 31, 2018									$ 78,811
Beginning Balance, Shares at Dec. 31, 2018			1,292,858
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	134				134
Stock issued on exercise of stock options, Shares			78,609
Stock-based compensation expense	738				738
Net loss	(37,037)						(37,037)
Unrealized (loss) gain on available-for-sale securities, net of tax	3							$ 3
Ending Balance at Dec. 31, 2019	$ (102,954)				2,879		(105,836)	3
Temporary Equity, Ending Balance, Shares at Dec. 31, 2019	117,809,883								117,809,883
Temporary Equity, Ending Balance at Dec. 31, 2019	$ 131,363								$ 131,363
Ending Balance, Shares at Dec. 31, 2019			1,371,467
Issuance of common stock upon the initial public offering, net		$ 92,050		$ 1		$ 92,049
Issuance of common stock upon initial public offering, net of issuance costs, Shares				6,468,750
Conversion of convertible preferred stock into common stock upon the initial public offering		$ 131,363		$ 1		$ 131,362
Temporary Equity, Conversion of convertible preferred stock into common stock upon initial public offering, Shares										(117,809,883)
Temporary Equity, Conversion of convertible preferred stock into common stock upon initial public offering										$ (131,363)
Conversion of convertible preferred stock into common stock upon the initial public offering, Shares				13,085,913
Stock issued on exercise of stock options	$ 77				77
Stock issued on exercise of stock options, Shares	53,134		53,135
Stock-based compensation expense	$ 1,788				1,788
Net loss	(27,531)						(27,531)
Unrealized (loss) gain on available-for-sale securities, net of tax	(7)							(7)
Ending Balance at Dec. 31, 2020	$ 94,786		$ 2		$ 228,155		$ (133,367)	$ (4)
Ending Balance, Shares at Dec. 31, 2020			20,979,265

Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statement of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating activities:
Net loss	$ (27,531)	$ (37,037)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,788	738
Depreciation	395	303
Change in fair value of preferred stock tranche obligation	(2,158)	(72)
Accretion of premium and discounts on short-term investments	1	(68)
Changes in operating assets and liabilities:
Prepaid expenses and other current and non-current assets	(2,400)	1,597
Accounts payable	(1,462)	1,403
Accrued research and development	(977)	640
Other current and non-current liabilities	280	1,281
Net cash used in operating activities	(32,064)	(31,215)
Investing activities:
Purchases of property and equipment	(1,023)	(605)
Purchases of short-term investments	(61,637)	(22,515)
Maturity of short-term investments	20,100	2,500
Net cash used in investing activities	(42,560)	(20,620)
Financing activities:
Proceeds from issuance of common stock upon initial public offering, net of underwriting discounts and commissions	96,255
Proceeds from issuance of convertible preferred stock, net of issuance costs		54,782
Proceeds from exercise of stock options	77	134
Payment of offering costs	(4,160)	(45)
Net cash provided by financing activities	92,172	54,871
Net increase in cash and cash equivalents	17,548	3,036
Cash and cash equivalents at beginning of period	15,870	12,834
Cash and cash equivalents at end of period	33,418	15,870
Supplemental disclosure of noncash items:
Deferred offering costs included in accounts payable and other current liabilities		849
Conversion of convertible preferred stock into common stock upon initial public offering	131,363
Property and equipment purchases included in accounts payable	$ 49	$ 126

Organization

12 Months Ended

Dec. 31, 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

In September 2020, the Company completed its initial public offering, or IPO, of shares of its common stock, 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 September 24, 2020. 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 issued and sold an aggregate of 6,468,750 shares of common stock (inclusive of 843,750 shares issued and sold pursuant to the exercise of the underwriters’ option to purchase additional shares on October 22, 2020) at a price of $16.00 per share for net proceeds of $92.0 million, after deducting underwriting discounts, commissions and offering expenses. Prior to the completion of the IPO, all 117,809,883 shares of 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 financial statements have been retroactively adjusted 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 years ended December 31, 2020 and 2019, and the Company’s accumulated deficit at December 31, 2020 is $133.4 million. 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 its 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. These events and conditions raise substantial doubt about the Company’s ability to continue as a going concern.

Based upon the Company’s current operating plan, the Company believes existing cash, cash equivalents and short-term investments will enable the Company to fund its operating expenses and capital expenditure requirements into the first quarter of 2022 but not at least 12 months from the issuance date of these financial statements. The Company bases this estimate on assumptions that may prove to be wrong, and it could utilize the available capital resources sooner than it currently expects. The Company currently plans to initiate two Phase 3 clinical trials for GB-102 in the second half of 2021. As such, the Company expects its cash and cash equivalents of $33.4 million and short-term investments of $61.6 million as of December 31, 2020, will be insufficient to fund its operating expenses and capital expenditure requirements for 12 months beyond the date of issuance of these financial statements. As a result, these conditions have raised substantial doubt about the Company’s ability to continue as a going concern. The future viability of the Company is dependent on its ability to raise additional capital to finance its operations and ultimately achieve profitable operations.

The Company will 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, such as partnering and equity financing. Such sources of capital may not, however, 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 December 31, 2020, the Company’s operations have not been significantly impacted by the COVID-19 pandemic. However, the Company cannot at this time predict the specific extent, duration, or full impact that the COVID-19 pandemic will have on its financial condition and operations, including ongoing and planned clinical trials. The impact of the COVID-19 pandemic on the financial performance of the Company will depend on future developments, including the duration and spread of the pandemic and related governmental advisories and restrictions. These developments and the impact of the COVID-19 pandemic on the financial markets, the life sciences sector, and the overall economy are highly uncertain and cannot be predicted. If the financial markets, the life sciences sector, 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.

In December 2020, the Consolidated Appropriations Act, 2021 was signed into law. The provisions within the law include the extension of the Investment Tax Credit for solar facilities, the extension and expansion of the CARES Act employee retention tax credit for the period from January 1, 2021 through June 30, 2021, including increasing the credit rate from 50 percent to 70 percent of qualified wages, and increasing the per-employee creditable wages limit from $10,000 per year to $10,000 for each quarter.

The enactment of the FFCR Act, CARES Act, A.B. 85, and Consolidated Appropriations Act, 2021, did not result in any material adjustments to the Company’s income tax provision for the year ended December 31, 2020 or to the Company’s net deferred tax assets as of December 31, 2020. Given the Company’s history of losses, the provisions of the FFCR Act, CARES Act, A.B. 85 and Consolidated Appropriations Act, 2021, did not have a material impact on the Company’s annual effective tax rate or 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.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America, or GAAP, and stated in U.S. dollars. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification, or ASC, and Accounting Standards Updates, or ASUs, of the Financial Accounting Standards Board, or FASB.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and reported amounts of expenses during the reporting periods. Actual results could differ from those estimates. On an ongoing basis, the Company evaluates its estimates, including those related to accrued research and development expenses, other long-lived assets, , stock-based compensation, the valuation of deferred tax assets, and the fair values of the Company’s Preferred Stock Tranche Obligation and common stock prior to the Company’s IPO. The Company bases its estimates using historical experience, Company forecasts and future plans, current economic conditions, and information from third-party professionals that management believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities and recorded amounts of expenses that are not readily apparent from other sources, and adjusts those estimates and assumptions when facts and circumstances dictate.

Prior to the IPO, management utilized estimates and assumptions in determining the fair value of its common stock, including stock-based awards. The Company has granted stock options at exercise prices that represented the fair value of its common stock on the specific grant dates. The Company utilized various valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants Technical Practice Aid, Valuation of Privately Held Company Equity Securities Issued as Compensation, or AICPA TPA, to estimate the fair value of its common stock. Each valuation methodology includes estimates and assumptions that require the Company’s judgment. These estimates and assumptions included a number of objective and subjective factors, including external market conditions, the prices at which the Company sold shares of convertible preferred stock, the superior rights and preferences of the convertible preferred stock senior to the Company’s common stock at the time, and a probability analysis of various liquidity events, such as a public offering or sale of the Company, under differing scenarios. Changes to the key assumptions used in the valuations could result in different fair values of common stock at each valuation date.

The Company’s results can also be affected by economic, political, legislative, regulatory and legal actions. Economic conditions, such as recessionary trends, inflation, interest, changes in regulatory laws and monetary exchange rates, and government fiscal policies, can have a significant effect on operations. While the Company maintains reserves for anticipated liabilities, the Company could be adversely affected by civil, criminal, regulatory or administrative actions, claims, or related proceedings.

Cash and Cash Equivalents

The Company considers all highly liquid investments with original maturities at the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents are stated at fair value and may include money market funds, corporate debt securities and commercial paper. The Company’s cash equivalents at December 31, 2020 consist of money market fund investments, corporate debt securities, and commercial paper. The Company’s cash equivalents at December 31, 2019 consist of money market fund investments and corporate debt securities.

Investments

The Company invests its excess cash balances in marketable government agency bonds, corporate debt securities and commercial paper. The Company classifies its investments as available-for-sale, reports available-for-sale investments at their fair value at each balance sheet date, and includes any unrealized holding gains and losses (the adjustment to fair value) in accumulated other comprehensive (loss) income, a component of stockholders’ equity (deficit). Should there be any realized gains or losses, they will be determined using the specific-identification method and included as other income or expense in the statements of operations. Should any adjustment to fair value reflect a decline in the value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is “other than temporary” and, if so, recognizes the associated unrealized loss through a charge to the statements of operations. The Company did not record any impairment charges related to its marketable securities during the years ended December 31, 2020 and 2019. The Company classifies its available-for-sale marketable securities as non-current if such instrument’s underlying effective maturity date exceeds 12 months and for which the Company has the intent and ability to hold the investment for a period of greater than 12 months. The Company’s marketable securities at December 31, 2020 and 2019 mature in less than 12 months and are included in short-term investments in the balance sheets.

Concentrations of Credit Risk and Off-balance Sheet Risk

Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash and cash equivalents and available-for-sale marketable securities. The Company’s investment policy includes guidelines regarding the quality of the financial institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. The Company may invest in money market funds, U.S. Treasury securities, corporate debt, U.S. government-related agency securities, commercial paper and certificates of deposit. At December 31, 2020 and 2019, the Company’s cash and cash equivalents were held in financial institutions that management believes are creditworthy. These deposits may exceed federally insured limits. The Company has not experienced any losses historically in these accounts and believes it is not exposed to significant credit risk in its cash and cash equivalents. The Company has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts, or other hedging arrangements.

Deferred Offering Costs

The Company capitalizes certain legal, professional accounting, and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. Capitalized deferred offering costs are included in prepaid expenses and other non-current assets in the Company’s balance sheet. After consummation of the Company’s IPO, these costs are recorded in stockholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering.

Property and Equipment

Property and equipment are stated at cost, subject to adjustments for impairments, less accumulated depreciation and amortization. Depreciation is calculated using the straight-line method over the useful lives of the assets as follows:

Asset		Estimated useful life
Manufacturing and laboratory equipment		Three to five years
Computer hardware		Three to five years
Office furniture and equipment		Three to five years

Leasehold improvements are amortized over the shorter of their useful lives or the related lease term. Maintenance and repairs that do not improve or extend the life of the respective asset are expensed to operations as incurred. Manufacturing and laboratory equipment received is classified as construction in progress until placed into service, at which time depreciation commences. Upon disposal of an asset, the related cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations.

Impairment of Long-lived Assets

The Company evaluates whether current facts or circumstances indicate that the carrying values of its long-lived assets may not be recoverable. If such facts or circumstances are determined to exist, an estimate of the sum of the undiscounted future cash flows of these assets is compared to the carrying value the assets to determine whether impairment exists. If the assets are determined to be impaired, the loss is measured based on the difference between the sum of the undiscounted future cash flows and the carrying value of the assets. No impairment losses were recorded during the years ended December 31, 2020 or 2019.

Research and Development Expenses

Research and development costs are expensed as incurred. The Company’s research and development expenses consist primarily of costs incurred for the development of its product candidates and include expenses incurred under agreements with contract manufacturing organizations, or CMOs, contract research organizations, or CROs, investigative sites and consultants to conduct clinical trials and preclinical and non-clinical studies, costs to acquire, develop and manufacture supplies for clinical trials and other studies, salaries and related costs, including stock-based compensation, depreciation and other allocated facility-related and overhead expenses.

Accrued Research and Development Costs

The Company records accruals for estimated costs of preclinical and clinical studies and manufacturing development. A portion of the Company’s clinical and manufacturing development activities are conducted by third-party service providers, including CROs and CMOs. The financial terms of these contracts are subject to negotiation, which vary by contract and may result in payments that do not match the periods over which materials or services are provided. The Company accrues the costs incurred under the agreements based on an estimate of actual work completed in accordance with the agreements. In the event the Company makes advance payments for goods or services that will be used or rendered for future research and development activities, the payments are deferred and capitalized as a prepaid expense and recognized as expense as the goods are received or the related services are rendered. Such payments are evaluated for current or non-current classification based on when they are expected to be realized. If the Company does not identify costs that have begun to be incurred or if the Company underestimates or overestimates the level of services performed or the costs of these services, actual expenses could differ from the Company’s estimates. To date, the Company has not experienced significant changes in its estimates of preclinical studies, clinical trial and manufacturing accruals.

Patent Costs

Costs to secure and maintain patents covering the Company’s technology and product candidates are expensed as incurred and are classified as general and administrative expenses in the statements of operations.

Convertible Preferred Stock

The Company classified convertible preferred stock outside of stockholders’ equity (deficit) on its balance sheet as of December 31, 2019, as the requirements of triggering a deemed liquidation event were not within the Company’s control. In the event of a deemed liquidation event, the proceeds from the event would have been distributed in accordance with liquidation preferences of such securities. The Company would have adjusted the carrying value of the convertible preferred stock to their redemption values when it became probable a redemption event would occur. 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.

Preferred Stock Tranche Obligation

The Company’s Series C convertible preferred stock included features the Company determined were not clearly and closely related to the equity host. These features were therefore bifurcated and accounted for separately as a freestanding derivative liability on the balance sheet at its estimated fair value. This derivative liability was a result of certain investors’ rights to purchase from the Company, on the same terms as the Series C Preferred Stock Purchase Agreement executed in July 2019, additional shares of Series C convertible preferred stock in subsequent tranches based on the achievement of certain development milestones, or the Preferred Stock Tranche Obligation. At initial recognition, the Company recorded this derivative as a liability on the balance sheet at its estimated fair value. The derivative was subject to remeasurement at each balance sheet date until its expiration in September 2020, with changes in fair value recognized in change in fair value of Preferred Stock Tranche Obligation on the Company’s statements of operations.

Stock-based Compensation

Stock-based compensation expense related to stock options and warrants granted to employees, directors and non-employees is recognized based on the grant-date estimated fair values of the awards using the Black-Scholes option pricing model, or Black-Scholes. The valuation of restricted stock units, or RSUs, is determined at the date of grant using the Company’s closing stock price. The value is recognized as expense ratably over the requisite service period, which is generally the vesting term of the award. The Company adjusts the expense for actual forfeitures as they occur.

Income Taxes

The Company uses the liability method to account for income taxes. Under this method, deferred tax assets and liabilities are determined based on temporary differences between the financial statement carrying amounts of existing assets and liabilities and their tax bases. Deferred tax assets and liabilities are measured using enacted tax rates applied to taxable income in the years in which those temporary differences are expected to be recovered or settled. A valuation allowance is established when necessary to reduce deferred tax assets to the amount expected to be realized.

The Company assesses the likelihood of deferred tax assets being realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. For the Company, the ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible. Based on the Company’s operations to date and the uncertainty as to the timing and amount of future taxable income, the Company has recorded a full valuation allowance in all periods and for all jurisdictions.

Financial statement effects of uncertain tax positions are recognized when it is more likely than not, based on the technical merits of the position, that it will be sustained upon examination. The Company evaluates uncertain tax positions on a regular basis. The evaluations are based on a number of factors, including changes in facts and circumstances, changes in tax law, correspondence with tax authorities during the course of an audit, and effective settlement of audit issues. Interest and penalties related to unrecognized tax benefits would be included within the income tax provision.

Net Loss Per Share

The Company calculates basic and diluted net loss per share attributable to common stockholders in conformity with the two-class method required for participating securities. While it was outstanding, the Company considered its convertible preferred stock to be participating securities as, in the event a dividend was paid on common stock, the holders of convertible preferred stock and unvested shares of common stock would have been entitled to receive dividends on a basis consistent with the common stockholders. The net loss attributable to common stockholders was not allocated to the convertible preferred stock as the holders of those securities did not have a contractual obligation to share in losses. Cumulative dividends on preferred stock were added to net loss to arrive at net loss available to common stockholders.

Under the two-class method, basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration of potential dilutive securities. Diluted net loss per share is calculated by dividing net loss by the weighted-average number of shares of common stock and potential dilutive common stock equivalents outstanding during the period if the effect is dilutive. Potentially dilutive securities include warrants, stock options, RSUs and convertible preferred stock. Likewise, adjustments to the denominator are required to reflect the related dilutive shares. In all periods presented, the Company’s outstanding stock options, RSUs, convertible preferred stock, common stock warrants, and the potential issuance of additional preferred shares from the Preferred Stock Tranche Obligation were excluded from the calculation of diluted net loss per share because their effects were antidilutive and the development milestones for the issuance of additional shares from the Preferred Stock Tranche Obligation were not achieved prior to its expiration in September 2020.

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 years ended December 31, 2020 and 2019, the costs incurred under this arrangement totaled $657,000 and $468,000, respectively, which costs were recorded as general and administrative expense in the accompanying statements of operations. As of December 31, 2019, amounts owed under this arrangement totaled $104,000, and are included in accounts payable in the accompanying balance sheets. There were no amounts owed under this arrangement as of December 31, 2020.

Segments

Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the chief operating decision maker, or CODM, in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its chief executive officer. The Company has determined it operates in one segment.

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period arising from transactions and other events and circumstances from non-owner sources. The Company’s comprehensive loss is comprised of changes in unrealized (loss) gain on available-for-sale securities.

Recently Adopted Accounting Pronouncements

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820), Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, or ASU 2018-13. ASU 2018-13 removed the following disclosure requirements: (1) the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy; (2) the policy for timing of transfers between levels; and (3) the valuation processes for Level 3 fair value measurements. Additionally, this update added the following disclosure requirements: (1) the changes in unrealized gains and losses for the period included in other comprehensive income and loss for recurring Level 3 fair value measurements held at the end of the reporting period; and (2) the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. For certain unobservable inputs, an entity may disclose other quantitative information, such as the median or arithmetic average, in lieu of the weighted average if the entity determines that other quantitative information would be a more reasonable and rational method to reflect the distribution of unobservable inputs used to develop Level 3 fair value measurements. ASU 2018-13 became effective for the Company beginning January 1, 2020 and the adoption of ASU 2018-13 did not have a material impact on the Company’s financial statements. For the disclosures regarding the Company’s Level 3 fair value measurements, see Note 3, to these financial statements.

Recently Issued Accounting Pronouncements

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), as amended, or ASU 2016-02, with guidance regarding the accounting for and disclosure of leases. The update requires lessees to recognize the liabilities related to all leases, including operating leases, with a term greater than 12 months on the balance sheet. This update also requires lessees and lessors to disclose key information about their leasing transactions. As an emerging growth company, this standard is effective for the Company for fiscal years beginning after December 15, 2021, and interim periods within annual periods beginning after December 15, 2022. Early adoption is permitted. The Company is currently assessing the potential impact of adopting ASU 2016-02 on its financial statements and financial statement disclosures.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments. ASU 2016-13 requires measurement and recognition of expected credit losses for financial assets. In April 2019, the FASB issued a clarification to ASU 2016-13 within ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, which modified the accounting for available-for-sale securities. As an emerging growth company, ASU 2016-13 is effective for the Company for fiscal years beginning after December 15, 2022, with early adoption permitted. The Company is currently assessing the potential impact of adopting ASU 2016-13 on its financial statements and financial statement disclosures.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which removes certain exceptions and amends certain requirements in the existing income tax guidance to ease accounting requirements. As an emerging growth company, this standard is effective for the Company for fiscal years beginning after December 15, 2021, and interim periods within annual periods beginning after December 15, 2022, and must be applied on a retrospective basis. The Company is currently evaluating the impact of this new guidance on its financial statements and disclosures.

Fair Value Measurements

12 Months Ended

Dec. 31, 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 three 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):

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Current assets:
Cash equivalents:
Money market funds	$	15,677	$	—	$	—	$	15,677
Corporate debt securities		—		2,500		—		2,500
Commercial paper		—		13,499		—		13,499
Total cash equivalents		15,677		15,999		—		31,676
Short-term investments:
Corporate debt securities		—		11,588		—		11,588
Commercial paper		—		50,027		—		50,027
Total short-term investments		—		61,615		—		61,615
Total assets measured at fair value	$	15,677	$	77,614	$	—	$	93,291

	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):

	December 31, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
Current assets:
Cash equivalents:
Money market funds	$	15,677	$	—	$	—		$	15,677
Corporate debt securities		2,502		—		(2	)		2,500
Commercial paper		13,498		1		—			13,499
Total cash equivalents		31,677		1		(2	)		31,676
Short-term investments:
Corporate debt securities		11,588		1		(1	)		11,588
Commercial paper		50,030		2		(5	)		50,027
Total short-term investments		61,618		3		(6	)		61,615
Total assets measured at fair value	$	93,295	$	4	$	(8	)	$	93,291

	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 is 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.

As of December 31, 2020 and 2019, the contractual maturities of all available-for-sale investments were less than 12 months. The Company periodically reviews the available-for-sale investments for other-than-temporary impairment loss. All investments with unrealized losses have been in a loss position for less than 12 months. As a result, the Company did not recognize any other-than-temporary impairment losses as of December 31, 2020 and 2019.

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 (the Preferred Stock Tranche Obligation, see Note 6). In September 2020, the board of directors 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 IPO registration statement on September 24, 2020. As a result, the fair value of 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 remeasured 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 fair 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 year ended December 31, 2020 was $2.2 million.

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 December 31, 2019	$	2,158
Change in fair value and expiration of the preferred stock tranche obligation		(2,158	)
Balance as of December 31, 2020	$	—

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

Balance Sheet Components

12 Months Ended

Dec. 31, 2020

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

4. Balance Sheet Components

Prepaid Expenses and Oher Non-current assets

Prepaid expenses and other non-current assets consisted of the following (in thousands):

	December 31,
	2020		2019
Prepaid clinical and research expenses	$	—	$	1,462
Deferred offering costs		—		894
Deposits		608		58
Total prepaid expenses and other non-current assets	$	608	$	2,414

Property and Equipment, net

Property and equipment, net, consisted of the following (in thousands):

	December 31,
	2020			2019
Manufacturing and laboratory equipment	$	2,179		$	1,863
Computer hardware		28			28
Office furniture and equipment		28			28
Leasehold improvement		234			—
Construction in progress		611			795
Total property and equipment, at cost		3,080			2,714
Less: accumulated depreciation		(1,134	)		(739	)
Property and equipment, net	$	1,946		$	1,975

Depreciation expense for the years ended December 31, 2020 and 2019 was $395,000 and $303,000, respectively.

Other Current Liabilities

Other current liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Salaries and benefits	$	2,302	$	2,044
Professional services		425		946
Deferred rent		27		—
Other		374		134
Total other current liabilities	$	3,128	$	3,124

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

5. Commitments and Contingencies

We enter into contracts in the normal course of business with CROs for clinical trials and CMOs for clinical supply manufacturing and with vendors for equipment, preclinical research studies, research supplies and other services and products for operating purposes. As of December 31, 2020, these commitments were approximately $7.7 million due within 3 to 15 months. These contracts generally provide for termination on notice of 60 to 90 days, and therefore we believe that our non-cancelable obligations under these agreements are not material.

Operating Lease Agreements

The Company leases a facility in Redwood City, California under an operating lease with a term through August 2021 and in Baltimore, Maryland under an operating lease with a term through June 2023. Rent expense for the years ended December 31, 2020 and 2019 was $732,000 and $696,000, respectively. Future minimum lease payments under the Company’s non–cancelable operating leases as of December 31, 2020 were as follows (in thousands):

Year ended December 31:
2021	$	658
2022		403
2023		205
Total future minimum lease payments	$	1,266

License Agreements

Johns Hopkins University

In June 2011, the Company entered into an Exclusive License Agreement with Johns Hopkins University, or JHU, which has been amended from time to time, such agreement as amended is referred to as the JHU Agreement. Pursuant to the JHU Agreement, JHU granted the Company an exclusive, worldwide, sublicensable license to three patent families to research, develop, make, use and sell products and provide services in any field, and a non-exclusive license to use specified know-how and materials with a provision that JHU will not grant a license to know how and materials to any other commercial entity. The JHU first patent family describes microparticles with a hydrophobic polymeric core (such as poly(lactic-co-glycolic acid), or PLGA, poly-lactic acid, or PLA, or a combination of both PLGA and PLA) and a hydrophilic coating (such as PLGA permanently linked to polyethylene glycol) to reduce inflammation for intraocular injections and their methods of use, which technology is incorporated into the Company’s GB-102, GB-103 and GB-401 product candidates. The JHU licensed fourth and fifth patent families cover potential future technologies.

In September 2015, the JHU Agreement was amended to include the JHU second patent family which covers sunitinib-encapsulated polymeric microparticles, including GB-102 and GB-103, and their use as therapeutic compositions to treat disorders of the eye. Under the terms of the amended JHU Agreement, the Company paid a one-time, non-refundable upfront fee, with a remaining amount to be paid upon the occurrence of certain events. The Company also agreed to pay an additional one-time, non-refundable fee of $100,000 on the occurrence of the first commercial sale of a product falling under the claims of a patent in the second patent family.

In April 2016, the JHU Agreement was further amended to include a third patent family which discloses a method for reducing neuronal damage in the eye that includes administration of a sustained release formulation of a dual leucine kinase inhibitor in a polymeric particle, and wherein the dual leucine kinase inhibitor may be sunitinib, and thus is relevant to both the Company’s GB-102 and GB-103 product candidates. Under the terms of the amended JHU Agreement, the Company paid a one-time, non-refundable upfront fee, and a milestone payment for the grant of the first patent. The Company also agreed to use its best efforts to develop a licensed product under the third patent family and enter into a Phase I clinical trial on or before April 2019, and to have cumulatively spent several million dollars on research and development within six years of execution of the amendment.

Upon execution of the JHU Agreement in 2011, the Company paid JHU an upfront license fee in the low tens of thousands of dollars and issued to JHU a low single digit percentage of the Company’s equity interests as of such date. The Company also reimbursed JHU for the prosecution and maintenance costs incurred by JHU for the licensed patent rights prior to the Company entering into the JHU Agreement, and the Company is responsible for all of the ongoing costs relating to the prosecution and maintenance of the JHU patent rights licensed to the Company. The Company also agreed to pay minimum annual royalties in the tens of thousands of dollars per year until the first commercial sale of a licensed product or service.

The JHU Agreement further requires single-digit running royalties on the Company’s annual net sales, which may be reduced by 50% of any payments the Company makes to third parties for freedom to operate, up to a maximum credit of 50% of the running royalty rate otherwise due to JHU. Royalties must be paid on products that fall within a patent claim of an issued and unexpired patent or a pending patent application that has not been finally rejected or is pending for less than seven years. The Company also must pay developmental milestones for achieving certain clinical progression events, ranging from tens of thousands to hundreds of thousands dollars per event, which in the aggregate, total less than $2.0 million per product. Under the JHU Agreement, prior to the Kala Agreement renegotiation described below, the Company was responsible for paying each developmental milestone payment for the first three products to achieve such milestone, and milestones for the second and third products are reduced by 50%. The Company further agreed to pay a percentage of any sublicense consideration the Company receives.

The JHU Agreement will remain effective until (i) the later of the expiration date of the last-to-expire patents covered under the JHU Agreement or 20 years from the effective date; (ii) the termination by either party upon the bankruptcy or uncured breach of the other party or (iii) if the Company terminates the JHU Agreement, with a 90-day notification period. The Company may terminate the entire agreement or on a patent by patent basis if desired, subject to the 90-day notification period.

Milestone and royalty expenses under the JHU Agreement are classified as research and development expense and reimbursement of patent-related expenditures are classified as general and administrative expense in the statements of operations. Expense under the JHU Agreement is as follows (in thousands):

	Year Ended December 31,
	2020		2019
Research and development	$	38	$	194
General and administrative		165		201
Total JHU Agreement expense	$	203	$	395

Kala Pharmaceuticals, Inc.

A dispute arose between the Company, JHU and Kala Pharmaceuticals, Inc., or Kala, over rights licensed to the Company and Kala by JHU. In October 2014, the Company entered into a Settlement and License Agreement, or the Kala Agreement, with Kala and JHU, which settled all pending disputes and amended the Company’s and Kala’s existing license agreements with JHU and created new rights and obligations among the parties.

Under the Kala Agreement, each of Kala and the Company provided the other with a royalty-free, exclusive sublicense with respect to certain intellectual property rights granted by JHU in limited fields of use. Specifically, the Company provided Kala with an exclusive sublicense for the use of a particle with specific characteristics for delivery of a biologically active material through mucus, mucin, or a mucosal barrier (provided that such delivery does not involve administration via injection to the eye), or the Kala Field of Use, and Kala provided the Company with an exclusive sublicense to the use of a particle with specific characteristics for delivery of a biologically active material to the eye via injection (excluding such use of any particle comprising or consisting of loteprednol etabonate). Kala also agreed not to use a particle with those specific characteristics that include sunitinib in any technology licensed the Kala Field of Use under the license from the Company or JHU. Neither the Company nor Kala owe JHU any payments under its existing JHU agreement with respect to the sublicenses granted to the other. Both the Company and Kala hold rights to sublicense the Company’s respective rights in connection with a future collaboration arrangement and subject to any such sublicensee being bound by the applicable terms of the Kala Agreement.

Under the Kala Agreement, JHU agreed to a number of financial concessions to both the Company and Kala. The payments under the existing JHU agreements were modified by reducing all milestones and minimum annual royalties by 25%, including the development milestone payments due for the first licensed product; the development milestone payments due for the first license product were each extended by one year; development milestone payments for the second and third licensed products were eliminated; and the commercial milestone payments for the first commercial sale of a licensed product were reduced by 50% in the United States. New sales-based milestones were added for the second and third licensed products. Upon the second licensed product under the JHU Agreement reaching a certain level of sales or receiving sublicense royalty income, the Company is required to pay $100,000 plus the amounts of the eliminated development milestones and reduced first commercial sale milestone. For the third licensed product, on reaching the same level of sales or receiving sublicense royalty income, the Company is required to pay $150,000 plus the amounts of the eliminated development milestones and reduced first commercial sale milestone. In addition, the Company, Kala and JHU released each other from any liability or claims known to Kala and the Company as of the Kala Agreement and arising out of the actions leading to, and related to the subject of, the Kala Agreement.

The Kala Agreement will expire upon the expiration of all the patent rights that are the subject of the agreement. The Company may terminate one or more of the licenses or sublicenses granted to the Company in the Kala Agreement on a country-by-country basis for convenience upon 30 days’ prior written notice to Kala. The Company or Kala may terminate one or more of the sublicenses granted to the other party under the JHU patent rights if the other party, or its employees, officers, directors, agents or representatives, takes certain steps to oppose, attempt to invalidate or prevent the issuance of any of the patent rights directly licensed to the terminating party by JHU.

There have been no expenses under the Kala Agreement in the years ended December 31, 2020 or 2019 and no amounts payable at December 31, 2020 or 2019.

AffaMed Project Limited

In July 2019, the Company entered into a letter agreement with AffaMed Project Limited, or AffaMed, in connection with their purchase of the Company’s Series C convertible preferred stock, or the AffaMed Letter. Under the AffaMed Letter, the Company granted AffaMed a right of first negotiation, or the Option, to exclusively develop, register and commercialize GB-102 solely in the territories of China, Hong Kong, Taiwan, Macau and South Korea. The Option expires upon the earlier of (i) July 31, 2021 and (ii) 60 days after the Company provides top line data from the Phase 2b ALTISSIMO trial for GB-102. If AffaMed does not exercise the Option, the Company will have no further obligation to AffaMed to license rights to GB-102.

The AffaMed Letter provides AffaMed with an initial 30-day period to propose terms for such a license which, if such terms are approved by a majority of the Company’s board of directors (excluding the director originally appointed by AffaMed and who continues to serve on our board), shall lead to a 60-day exclusive negotiation period. During this period of up to 90 days, the Company is prohibited from soliciting, initiating, encouraging or assisting the submission of any other proposal, negotiation or offer for the development, registration and commercialization of GB-102 in China, Hong Kong, Taiwan, Macau or South Korea.

The Company may enter into a license agreement for such services with AffaMed if approved by a majority of the members of the Company’s board of directors excluding the director originally appointed by AffaMed during the exclusive negotiation period. If the Company’s board of directors does not approve AffaMed’s proposed terms under the Option following good faith negotiations and, following a further 10 business day period of discussion if requested by AffaMed, the Company has the right to enter into an alternative license agreement with any third party for such services. If AffaMed does not exercise its Option, the Company has the right to enter into an alternative license agreement with a different party. The AffaMed Letter does not limit the Company’s ability to develop, register and commercialize GB-102 in territories other than China, Hong Kong, Taiwan, Macau and South Korea.

There have been no expenses under the Affamed Letter in the years ended December 31, 2020 or 2019 and no amounts payable at December 31, 2020 or 2019.

Indemnification

The Company, as permitted under Delaware law and in accordance with its certification of incorporation and bylaws and pursuant to indemnification agreements with certain of its officers and directors, indemnifies its officers and directors for certain events or occurrences, subject to certain limits, which the officer or director is or was serving at the Company’s request in such capacity.

The Company enters into certain types of contracts that contingently require the Company to indemnify various parties against claims from third parties. These contracts primarily relate to (i) the Company’s bylaws, under which the Company must indemnify directors and executive officers, and may indemnify other officers and employees, for liabilities arising out of their relationship, (ii) contracts under which the Company must indemnify directors and certain officers and consultants for liabilities arising out of their relationship, and (iii) procurement, service or license agreements under which the Company may be required to indemnify vendors, service providers or licensees for certain claims, including claims that may be brought against them arising from the Company’s acts or omissions with respect to the Company’s products, technology, intellectual property or services.

From time to time, the Company may receive indemnification claims under these contracts in the normal course of business. In the event that one or more of these matters were to result in a claim against the Company, an adverse outcome, including a judgment or settlement, may cause a material adverse effect on the Company’s future business, operating results or financial condition. It is not possible to determine the maximum potential amount potentially payable under these contracts since the Company has no history of prior indemnification claims and the unique facts and circumstances involved in each particular claim will be determinative.

Convertible Preferred Stock and Stockholders’ Equity (Deficit)

12 Months Ended

Dec. 31, 2020

Temporary Equity Disclosure [Abstract]

Convertible Preferred Stock and Stockholders’ Equity (Deficit)

6. 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 Company’s IPO registration statement. As a result, the liability for the Preferred Stock Tranche Obligation was permanently eliminated as of September 24, 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.

The rights and preferences and privileges of convertible preferred stock are described below:

Dividend Rights

The holders of Series C Preferred, in preference to holders of Series B Preferred, Series A-2 Preferred, Series A Preferred and common stock, are entitled to receive cumulative dividends on each outstanding share payable when declared by the board of directors of $0.117544 per share. After payment of such dividends on the Series C Preferred, the holders of Series B Preferred, in preference to holders of Series A-2 Preferred, Series A Preferred and common stock, are entitled to receive cumulative dividends on each outstanding share payable when declared by the board of directors of $0.06937 per share. After payment of such dividends on the Series B Preferred, the holders of Series A-2 Preferred, in preference to the holders of Series A Preferred and common stock, are entitled to receive non-cumulative dividends on each outstanding share payable when declared by the board of directors of $0.06034 per share. After payment of such dividends on the Series A-2 Preferred, the holders of Series A Preferred, in preference to the holders of common stock, are entitled to receive non-cumulative dividends on each outstanding share payable when declared by the board of directors of $0.08 per share. The board of directors has not declared any dividends to-date.

Conversion Rights

Each share of convertible preferred stock is convertible at the option of the holder, at any time after the date of issuance, into a fully paid and non-assessable share of common stock. Each share of convertible preferred stock is convertible into that number of common shares as is determined by dividing the applicable original purchase price of such share by the applicable conversion price. The conversion rate is subject to adjustment upon the occurrence of certain events. The conversion rates for the Series C Preferred, Series B Preferred and Series A-2 Preferred is 9.0058:1 and for the Series A Preferred is 8.8527:1.

All shares of the convertible preferred stock automatically convert upon the closing of a firm commitment underwritten initial public offering of common stock, in which the price per share is at least $14.56 per share, subject to adjustment, resulting in gross proceeds of at least $40.0 million. The conversion price for each series of convertible preferred stock is subject to adjustment in the event of stock split, combination, common stock dividend or distribution, reclassification, exchange, substitution, reorganization, and certain antidilution adjustments.

Liquidation Rights

In the event of any liquidation, dissolution, or winding up of the Company or a deemed liquidation event, the holders of Series C Preferred are entitled to receive, prior to any distribution made to any other class of security, an amount equal to $1.4693 per share, plus any dividends accrued and declared but unpaid. Upon distribution to holders of Series C Preferred, the holders of Series B Preferred are entitled to receive, prior to distribution to holders of Series A-2 Preferred, Series A Preferred and common stock, an amount equal to $0.991 per share, plus any dividends accrued and declared but unpaid. Upon distribution to holders of Series C Preferred and Series B Preferred, the holders of Series A-2 Preferred are entitled to receive, prior to distribution to holders of Series A Preferred and common stock, an amount equal to $0.862 per share, plus any dividends declared but unpaid. Upon distributions to the holders of Series C Preferred, Series B Preferred and Series A-2 Preferred, the holders of Series A Preferred are entitled to receive, prior to any distribution or payment to the holders of common stock, an amount equal to $1.00 per share, plus any dividends declared but unpaid. Upon the completion of the distribution to the holders of Series C Preferred, Series B Preferred, Series A-2 Preferred and Series A Preferred, any remaining assets available for distribution will be distributed among the holders of the shares of Series C Preferred, Series B Preferred, Series A-2 Preferred, Series A Preferred and common stock, on a pro rata basis on the number of shares held by each such holder, treating each share as if they had been converted to common stock immediately prior to such liquidation, dissolution or winding up of the Company.

Voting Rights

Each share of Series A Preferred has voting rights equal to the number of common shares into which the Series A Preferred can be converted. Shares of Series A-2 Preferred, Series B Preferred and Series C Preferred do not have voting rights.

The holders of Series C Preferred are entitled to elect one director of the Company; the holders of Series B Preferred are entitled to elect three directors of the Company; the holders of Series A-2 Preferred, are entitled to elect one director; the holders of common stock are entitled to elect one director; and holders of common stock and any other class or series of voting stock, exclusively and voting together as a single class on an as-converted basis, are entitled to elect one director. Holders of Series A Preferred are not entitled to a director of the Company.

Redemption Rights

Shares of Series C Preferred, Series B Preferred and Series A-2 Preferred may be redeemed at the greater of the fair market value or the original issue price for the applicable series of convertible preferred stock plus any dividends accrued but unpaid with respect to the Series C Preferred and the Series B Preferred and any dividend declared by unpaid with respect to the Series A-2 Preferred. A redemption will occur upon a written request from the holders of a majority of the then outstanding shares of Series C Preferred, voting exclusively as a separate series, and the holders of a majority of the Series B Preferred and Series A-2 Preferred, voting together on an as-converted basis, which request can be made at any time after July 2024.

Cumulative dividends and accretion of discount on Series A-2 Preferred, Series B Preferred and Series C Preferred, together the Contingently Redeemable Preferred, is not recorded until the Contingently Redeemable Preferred is probable of becoming redeemable. As of December 31, 2019, the Company has determined that the Contingently Redeemable Preferred are not currently probable of becoming redeemable and, as such, the cumulative dividend and accretion of discount on the Contingently Redeemable Preferred has not been recorded.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

7. 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 units, or RSUs, restricted stock awards, or RSAs, stock appreciation rights, or SARs, 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 December 31, 2020, there were 1,686,158 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 Option Activity

The following summarizes stock option activity:

						Weighted
				Weighted		Average
				Average		Remaining		Aggregate
	Number of			Exercise		Contractual		Intrinsic
	Options			Price		Term		Value
						(In years)		(In thousands)
Outstanding—December 31, 2019		2,117,106		$	2.52		8.7	$	2,825
Granted		1,098,542		$	16.88
Exercised		(53,134	)	$	1.47
Forfeited and Canceled		(406,412	)	$	2.38
Outstanding—December 31, 2020		2,756,102		$	8.28		8.6	$	57,090
Options Exercisable—December 31, 2020		1,925,666		$	3.00		8.1	$	50,109

At December 31, 2019, the aggregate intrinsic value of options granted is calculated as the difference between the exercise price of the options and the estimated fair value of the Company’s common stock on the same date. At December 31, 2020, the aggregate intrinsic value of options granted is calculated as the difference between the exercise price and the closing price on the same date. The aggregate intrinsic value of options exercised in the years ended December 31, 2020 and 2019 was $113,000 and $157,000, respectively.

The aggregate fair value of options that vested during the years ended December 31, 2020 and 2019 was $1.4 million and $659,000, respectively. The weighted-average grant-date fair value per share of options that vested during the years ended December 31, 2020 and 2019 was $2.43 and $1.44, respectively.

Restricted Stock Units

During the year ended December 31, 2020, the Company issued 80,000 RSUs under the 2020 Plan. The weighted-average grant-date fair value per share of the RSUs was $16.50. As of December 31, 2020, none of the RSUs had vested or forfeited.

Fair Value of Stock Option Awards

The Company estimates the fair value of stock option awards on the grant date using Black-Scholes. The weighted-average grant date fair value per option granted during the years ended December 31, 2020 and 2019 was $11.90 and $2.16, respectively. The fair value of each award is estimated using Black-Scholes based on the following assumptions:

	Year Ended December 31,
	2020		2019
Expected term (years)	5.0-6.1		5.1-6.1
Expected volatility	85%		80%
Risk-free interest rate	0.25%-0.53%		1.8%-2.5%
Expected dividend		—		—

Black-Scholes requires the use of subjective assumptions which determine the fair value of stock-based awards. These assumptions include:

Expected Term: The expected term represents the period that options are expected to be outstanding and is determined using the simplified method, based on the mid-point between the vesting date and the end of the contractual term.

Expected Volatility: The expected volatility is estimated based on the average volatility for comparable publicly-traded biopharmaceutical companies over a period equal to the expected term of the stock option grants as the Company does not yet have sufficient historical trading history for its own stock. The comparable companies are chosen based on their similarities to the Company, including life cycle stage, therapeutic focus and size. The Company will continue to apply this method until a sufficient amount of historical information over a period equal to the expected term of the stock-based awards becomes available.

Risk-free Interest Rate. The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of the stock option grants.

Expected Dividend: The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

Stock-Based Compensation Expense

Stock-based compensation expense is classified as follows (in thousands):

	Year Ended December 31,
	2020		2019
Research and development	$	390	$	215
General and administrative		1,398		523
Total stock-based compensation expense	$	1,788	$	738

As of December 31, 2020, the total unrecognized stock-based compensation expense related to outstanding unvested stock awards that are expected to vest was $15.0 million, which the Company expects to recognize over an estimated weighted-average term of 3.5 years.

During the year ended December 31, 2019, the Company accelerated the vesting of 61,812 unvested stock options and extended the exercise period related to the awards. The modification resulted in additional stock-based compensation of $128,000.

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

8. Income Taxes

The Company has incurred net operating losses for all the periods presented. The Company has not reflected the benefit of any such net operating loss carryforwards in the accompanying financial statements.

The effective tax rate for the years ended December 31, 2020 and 2019 is different from the federal statutory rate primarily due to the valuation allowance against deferred tax assets as a result of insufficient sources of income. The reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows:

	Year Ended December 31,
	2020			2019
Income tax benefit at the federal statutory rate		21.0	%		21.0	%
State income taxes, net of federal benefit	3.2				1.1
Research and development tax credits	1.3				2.8
Other		(0.6	)		(0.3	)
Mark to market gain/loss	1.7				—
Change in valuation allowance		(26.6	)		(24.6	)
Total		—	%		—	%

Deferred income taxes reflect the net effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The principal components of the Company’s net deferred tax assets consisted of the following (in thousands):

	December 31,
	2020			2019
Deferred tax assets
Federal and state net operating loss carryforwards	$	27,567		$	21,262
Research and development tax credits		4,887			4,140
Other		748			488
Gross deferred tax assets		33,202			25,890
Less: valuation allowance		(33,141	)		(25,841	)
Total deferred tax assets		61			49
Deferred tax liabilities
Depreciation		(61	)		(49	)
Total deferred tax liabilities		(61	)		(49	)
Net deferred tax assets	$	—		$	—

The Company has incurred annual net operating losses in each year since inception. The Company has not reflected the benefit of any such net operating loss carryforwards in the financial statements. Due to the Company’s history of losses, and lack of other positive evidence, the Company has determined that it is more likely than not that its net deferred tax assets will not be realized and, therefore, the net deferred tax assets are fully offset by a valuation allowance at December 31, 2020 and 2019. The Company increased its valuation allowance by $7.3 million for the year ended December 31, 2020 in order to maintain a full valuation allowance against its deferred tax assets.

As of December 31, 2020, the Company had federal net operating loss carryforwards, or NOLs, of $125.4 million and federal tax credits of $5.4 million available to offset tax liabilities. The Company’s federal NOLs and federal tax credit carryforwards begin to expire in 2035 and 2036, respectively. Of the federal NOLs, $91.3 million have an indefinite life. The Company also had gross state NOLs of $20.2 million and state tax credits of $1.8 million which are available to offset state tax liabilities. The state NOLs expire in 2036 and the state tax credit carryforwards can be carried forward indefinitely. Federal and state NOLs and tax credit carryforwards are also subject to annual limitations in the event that cumulative changes in the ownership interests of significant stockholders exceed 50% over a three-year period, as defined under Sections 382 and 383 of the Internal Revenue Code of 1986. The Company has not completed an analysis to determine if the NOLs and tax credits are limited due to a change in ownership. Should there be ownership changes that occurred, the Company’s ability to utilize existing carryforwards could be substantially restricted.

The Company determines its uncertain tax positions based on whether and how much of a tax benefit taken by the Company in its tax filings is more likely than not to be sustained upon examination by the relevant income tax authorities.

A reconciliation of the unrecognized tax benefit is as follows (in thousands):

	Year Ended December 31,
	2020		2019
Balance—beginning of year	$	1,406	$	873
Addition based on tax position related to current year		406		533
Addition based on tax position related to prior year		169		—
Balance—end of year	$	1,981	$	1,406

The unrecognized tax benefits, if recognized, would not have an impact on the Company’s effective tax rate assuming the Company continues to maintain a full valuation allowance position. Based on prior year’s operations and experience, the Company does not expect a significant change to its unrecognized tax benefits over the next twelve months. The unrecognized tax benefits may increase or change during the next year for unexpected or unusual items for items that arise in the ordinary course of business.

The Company files income tax returns in the U.S., California, Florida, Illinois, Indiana, Maryland, Massachusetts and Texas. Due to net operating loss carryforwards, all years remain open for income tax examination, however, the Company is not currently under examination by any taxing authority for any open tax year.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Cash and Cash Equivalents

Investments

Concentrations of Credit Risk and Off-balance Sheet Risk

Deferred Offering Costs

Property and Equipment

Asset		Estimated useful life
Manufacturing and laboratory equipment		Three to five years
Computer hardware		Three to five years
Office furniture and equipment		Three to five years

Impairment of Long-lived Assets

Research and Development Expenses

Accrued Research and Development Costs

Patents Costs

Patent Costs

Convertible Preferred Stock

Preferred Stock Tranche Obligation

Stock-based Compensation

Income Taxes

Net Loss Per Share

Related Party Transactions

Segments

Comprehensive Loss

Recently Adopted and Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

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

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Current assets:
Cash equivalents:
Money market funds	$	15,677	$	—	$	—	$	15,677
Corporate debt securities		—		2,500		—		2,500
Commercial paper		—		13,499		—		13,499
Total cash equivalents		15,677		15,999		—		31,676
Short-term investments:
Corporate debt securities		—		11,588		—		11,588
Commercial paper		—		50,027		—		50,027
Total short-term investments		—		61,615		—		61,615
Total assets measured at fair value	$	15,677	$	77,614	$	—	$	93,291

	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

	December 31, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
Current assets:
Cash equivalents:
Money market funds	$	15,677	$	—	$	—		$	15,677
Corporate debt securities		2,502		—		(2	)		2,500
Commercial paper		13,498		1		—			13,499
Total cash equivalents		31,677		1		(2	)		31,676
Short-term investments:
Corporate debt securities		11,588		1		(1	)		11,588
Commercial paper		50,030		2		(5	)		50,027
Total short-term investments		61,618		3		(6	)		61,615
Total assets measured at fair value	$	93,295	$	4	$	(8	)	$	93,291

	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 December 31, 2019	$	2,158
Change in fair value and expiration of the preferred stock tranche obligation		(2,158	)
Balance as of December 31, 2020	$	—

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2020

Balance Sheet Related Disclosures [Abstract]

Schedule of Prepaid Expenses and Other Non-current Assets

Prepaid expenses and other non-current assets consisted of the following (in thousands):

	December 31,
	2020		2019
Prepaid clinical and research expenses	$	—	$	1,462
Deferred offering costs		—		894
Deposits		608		58
Total prepaid expenses and other non-current assets	$	608	$	2,414

Schedule of Property and Equipment and Depreciation Calculated using Straight-line Method over useful Life of Asset

Depreciation is calculated using the straight-line method over the useful lives of the assets as follows:

Asset		Estimated useful life
Manufacturing and laboratory equipment		Three to five years
Computer hardware		Three to five years
Office furniture and equipment		Three to five years

Property and equipment, net, consisted of the following (in thousands):

	December 31,
	2020			2019
Manufacturing and laboratory equipment	$	2,179		$	1,863
Computer hardware		28			28
Office furniture and equipment		28			28
Leasehold improvement		234			—
Construction in progress		611			795
Total property and equipment, at cost		3,080			2,714
Less: accumulated depreciation		(1,134	)		(739	)
Property and equipment, net	$	1,946		$	1,975

Schedule of Other Current Liabilities

Other current liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Salaries and benefits	$	2,302	$	2,044
Professional services		425		946
Deferred rent		27		—
Other		374		134
Total other current liabilities	$	3,128	$	3,124

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following summarizes stock option activity:

						Weighted
				Weighted		Average
				Average		Remaining		Aggregate
	Number of			Exercise		Contractual		Intrinsic
	Options			Price		Term		Value
						(In years)		(In thousands)
Outstanding—December 31, 2019		2,117,106		$	2.52		8.7	$	2,825
Granted		1,098,542		$	16.88
Exercised		(53,134	)	$	1.47
Forfeited and Canceled		(406,412	)	$	2.38
Outstanding—December 31, 2020		2,756,102		$	8.28		8.6	$	57,090
Options Exercisable—December 31, 2020		1,925,666		$	3.00		8.1	$	50,109

Schedule of Assumptions Using Black-Scholes to Estimate Fair Value of Each Awards

The fair value of each award is estimated using Black-Scholes based on the following assumptions:

	Year Ended December 31,
	2020		2019
Expected term (years)	5.0-6.1		5.1-6.1
Expected volatility	85%		80%
Risk-free interest rate	0.25%-0.53%		1.8%-2.5%
Expected dividend		—		—

Summary of Stock-Based Compensation Expense

Stock-based compensation expense is classified as follows (in thousands):

	Year Ended December 31,
	2020		2019
Research and development	$	390	$	215
General and administrative		1,398		523
Total stock-based compensation expense	$	1,788	$	738

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of Federal Statutory Income Tax Rate to Effective Income Tax Rate

The reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows:

	Year Ended December 31,
	2020			2019
Income tax benefit at the federal statutory rate		21.0	%		21.0	%
State income taxes, net of federal benefit	3.2				1.1
Research and development tax credits	1.3				2.8
Other		(0.6	)		(0.3	)
Mark to market gain/loss	1.7				—
Change in valuation allowance		(26.6	)		(24.6	)
Total		—	%		—	%

Schedule of Components of Deferred Tax Assets

The principal components of the Company’s net deferred tax assets consisted of the following (in thousands):

	December 31,
	2020			2019
Deferred tax assets
Federal and state net operating loss carryforwards	$	27,567		$	21,262
Research and development tax credits		4,887			4,140
Other		748			488
Gross deferred tax assets		33,202			25,890
Less: valuation allowance		(33,141	)		(25,841	)
Total deferred tax assets		61			49
Deferred tax liabilities
Depreciation		(61	)		(49	)
Total deferred tax liabilities		(61	)		(49	)
Net deferred tax assets	$	—		$	—

Schedule of Reconciliation of Unrecognized Tax Benefits

A reconciliation of the unrecognized tax benefit is as follows (in thousands):

	Year Ended December 31,
	2020		2019
Balance—beginning of year	$	1,406	$	873
Addition based on tax position related to current year		406		533
Addition based on tax position related to prior year		169		—
Balance—end of year	$	1,981	$	1,406

Organization - Additional Information (Details)					1 Months Ended		6 Months Ended	12 Months Ended
Organization - Additional Information (Details)	Oct. 22, 2020 shares	Sep. 29, 2020 USD ($) $ / shares shares	Sep. 24, 2020 shares	Sep. 18, 2020	Dec. 31, 2020 USD ($)	Mar. 31, 2020	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Net proceeds from shares issued								$ 96,255,000
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 financial statements have been retroactively adjusted 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.
Reverse stock split				0.111039552
Accumulated deficit					$ 133,367,000			$ 133,367,000	$ 105,836,000
Cash and cash equivalents					33,418,000			33,418,000	15,870,000
Short-term investments					$ 61,615,000			$ 61,615,000	$ 20,086,000
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.
Employee retention tax credit period, start date					Jan. 01, 2021
Employee retention tax credit period, end date					Jun. 30, 2021
Credit rate percent of qualified wages					50.00%
Creditable wages limit per year					$ 10,000			$ 10,000
Forecast
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Credit rate percent of qualified wages							70.00%
Creditable wages limit per quarter							$ 10,000
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		6,468,750						6,468,750
Shares issued and sold, price per share \| $ / shares		$ 16.00
Number of shares purchased in additional pursuant to underwriters' option \| shares	843,750
Net proceeds from shares issued		$ 92,000,000
Conversion of convertible preferred stock into common stock upon initial public offering \| shares			117,809,883
Outstanding redeemable convertible preferred stock converted to common stock \| shares			13,085,913

Summary of Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Sep. 24, 2020 shares	Dec. 31, 2020 USD ($) Segment	Dec. 31, 2019 USD ($) shares	Sep. 30, 2020 shares	Sep. 29, 2020 shares
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Impairment losses		$ 0	$ 0
Shares outstanding \| shares			117,809,883	0	0
Accounts payable, related parties		$ 0	$ 104,000
Number of operating segment \| Segment		1
Accounting Standards Update 2018-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted		true
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect		true
General and Administrative
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Related party transaction, costs incurred		$ 657,000	$ 468,000
Initial Public Offering
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Convertible preferred stock converted into common stock \| shares	13,085,913

Commitments and Contingencies - Additional Information (Details) - USD ($)	1 Months Ended		12 Months Ended
	Sep. 30, 2015	Oct. 31, 2014	Dec. 31, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Rent expense			$ 732,000	$ 696,000
Operating expenses			29,832,000	37,502,000
Accounts payable			2,513,000	4,636,000
JHU
Loss Contingencies [Line Items]
Operating expenses			203,000	395,000
License Agreement \| JHU
Loss Contingencies [Line Items]
One-time, non-refundable fee	$ 100,000
Maximum credit percentage of running royalty rate	50.00%
Kala Agreement
Loss Contingencies [Line Items]
Percentage of minimum annual royalties including development milestone payments for first licensed product		25.00%
Development milestone payment extension period		1 year
Development milestone payable under second licensed product		$ 100,000
Development milestone payable under third licensed product		$ 150,000
Operating expenses			0	0
Accounts payable			0	0
AffaMed Letter
Loss Contingencies [Line Items]
Operating expenses			0	0
Accounts payable			$ 0	$ 0
Option expiration period			Jul. 31, 2021
Collaborative arrangement, description			The AffaMed Letter provides AffaMed with an initial 30-day period to propose terms for such a license which, if such terms are approved by a majority of the Company’s board of directors (excluding the director originally appointed by AffaMed and who continues to serve on our board), shall lead to a 60-day exclusive negotiation period. During this period of up to 90 days, the Company is prohibited from soliciting, initiating, encouraging or assisting the submission of any other proposal, negotiation or offer for the development, registration and commercialization of GB-102 in China, Hong Kong, Taiwan, Macau or South Korea.
Redwood City, California
Loss Contingencies [Line Items]
Operating lease, term			2021-08
Baltimore, Maryland
Loss Contingencies [Line Items]
Operating lease, term			2023-06
United States \| Kala Agreement
Loss Contingencies [Line Items]
Percentage of commercial milestone payments reduced		50.00%
Minimum \| License Agreement \| JHU
Loss Contingencies [Line Items]
Percentage of royalty payments on net sales	50.00%
Percentage of developmental milestone payment for second and third products	50.00%
Maximum \| License Agreement \| JHU
Loss Contingencies [Line Items]
Aggregate total amount of developmental milestone payment	$ 2,000,000
Research and Development
Loss Contingencies [Line Items]
Contractual obligation			$ 7,700,000
Research and Development \| Minimum
Loss Contingencies [Line Items]
Contractual obligation term			3 months
Research and Development \| Maximum
Loss Contingencies [Line Items]
Contractual obligation term			15 months

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Additional Information (Details) $ / shares in Units, $ in Thousands		1 Months Ended	2 Months Ended	12 Months Ended
	Sep. 24, 2020 shares	Jul. 31, 2019 $ / shares shares	Aug. 31, 2019 USD ($) shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares	Sep. 30, 2020 shares	Sep. 29, 2020 shares
Temporary Equity [Line Items]
Convertible preferred stock authorized to sell					142,150,096
Proceeds from issuance of convertible preferred stock, net of issuance costs \| $					$ 54,782
Shares outstanding					117,809,883	0	0
Preferred stock voting rights				The holders of Series C Preferred are entitled to elect one director of the Company; the holders of Series B Preferred are entitled to elect three directors of the Company; the holders of Series A-2 Preferred, are entitled to elect one director; the holders of common stock are entitled to elect one director; and holders of common stock and any other class or series of voting stock, exclusively and voting together as a single class on an as-converted basis, are entitled to elect one director. Holders of Series A Preferred are not entitled to a director of the Company.
Common stock, voting rights				one
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 \| $ / shares		$ 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 \| $ / shares		$ 1.4693
Shares outstanding					37,432,787
Dividends rights, amount per share on each outstanding share payable \| $ / shares				$ 0.117544
Convertible preferred stock, price per share \| $ / shares				$ 1.4693
Preferred stock voting rights				one
Series C Convertible Preferred Stock \| Current Liability
Temporary Equity [Line Items]
Fair value of preferred stock tranche obligation \| $					$ 2,200
Series B Preferred
Temporary Equity [Line Items]
Convertible preferred stock authorized to sell					76,078,535
Shares outstanding					76,078,535
Dividends rights, amount per share on each outstanding share payable \| $ / shares				$ 0.06937
Convertible preferred stock, price per share \| $ / shares				$ 0.991
Preferred stock voting rights				three
Series A-2
Temporary Equity [Line Items]
Convertible preferred stock authorized to sell					2,018,561
Shares outstanding					2,018,561
Dividends rights, amount per share on each outstanding share payable \| $ / shares				$ 0.06034
Convertible preferred stock, price per share \| $ / shares				$ 0.862
Preferred stock voting rights				one
Series A
Temporary Equity [Line Items]
Convertible preferred stock authorized to sell					2,280,000
Shares outstanding					2,280,000
Dividends rights, amount per share on each outstanding share payable \| $ / shares				$ 0.08
Preferred stock, convertible, conversion price				8.8527
Convertible preferred stock, price per share \| $ / shares				$ 1.00
Series C Preferred, Series B Preferred and Series A-2 Preferred
Temporary Equity [Line Items]
Preferred stock, convertible, conversion price				9.0058
Series A-2 Preferred, Series B Preferred and Series C Preferred
Temporary Equity [Line Items]
Preferred stock voting rights				Shares of Series A-2 Preferred, Series B Preferred and Series C Preferred do not have voting rights.
Maximum \| Series C Convertible Preferred Stock
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
Minimum
Temporary Equity [Line Items]
Convertible preferred stock, price per share \| $ / shares				$ 14.56
Proceeds from issuance of convertible preferred stock, net of issuance costs \| $				$ 40,000

Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Aug. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate number of shares issued over the term of the ESPP		20,979,265	1,371,467
Common stock shares reserved for future issuance		$ 113,000	$ 157,000
Aggregate fair value of options vested		$ 1,400,000	$ 659,000
Weighted average grant date fair value per share of options vested		$ 2.43	$ 1.44
Weighted-average grant date fair value per option granted		$ 11.90	$ 2.16
Total unrecognized stock-based compensation expenses related to outstanding unvested stock awards		$ 15,000,000
Total unrecognized stock-based compensation expenses related to outstanding unvested stock options weighted-average term of recognition		3 years 6 months
Accelerated vesting of unvested stock options			61,812
Modification resulted in additional stock-based compensation		$ 128,000,000
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	1,686,158
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 Equity Incentive Plan \| Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, equity instruments other than options, Shares issued during the period		80,000
Weighted average grant date fair value		$ 16.50
Share-based compensation arrangement by share-based payment award, equity instruments other than options, vested		0
Share-based compensation arrangement by share-based payment award, equity instruments other than options, forfeited		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

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options, Outstanding	2,117,106
Number of Options, Granted	1,098,542
Number of Options, Exercised	(53,134)
Forfeited and Canceled	(406,412)
Number of Options, Outstanding	2,756,102	2,117,106
Number of Options, Options Exercisable	1,925,666
Weighted Average Exercise Price, Outstanding	$ 2.52
Weighted Average Exercise Price, Granted	16.88
Weighted Average Exercise Price, Exercised	1.47
Forfeited and Canceled	2.38
Weighted Average Exercise Price, Outstanding	8.28	$ 2.52
Weighted Average Exercise Price, Options Exercisable	$ 3.00
Weighted Average Remaining Contractual Term, Outstanding	8 years 7 months 6 days	8 years 8 months 12 days
Weighted Average Remaining Contractual Term, Options Exercisable	8 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding	$ 57,090	$ 2,825
Aggregate Intrinsic Value, Options Exercisable	$ 50,109

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	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net loss	$ (27,531)	$ (37,037)
Cumulative dividends on convertible preferred stock	(7,189)	(7,055)
Net loss attributable to common stockholders	$ (34,720)	$ (44,092)
Net loss per common share—basic and diluted	$ (5.25)	$ (33.41)
Weighted-average number of shares outstanding used in computing net loss per common share—basic and diluted	6,618,445	1,319,912

- Definition

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

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

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+ Details

Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	500,000,000	188,000,000
Common stock, shares issued	20,979,265	1,371,467
Common stock, shares outstanding	20,979,265	1,371,467
Convertible Preferred Stock
Preferred stock, par value		$ 0.0001
Preferred stock, shares authorized		142,150,096
Preferred stock, shares issued	0	117,809,883
Preferred stock, shares outstanding	0	117,809,883
Preferred stock, aggregate liquidation value	$ 0	$ 148,592

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Offering and Issuance costs	$ 45
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 - Schedule of Depreciation Calculated using Straight-line Method over useful Life of Asset (Details)	12 Months Ended
	Dec. 31, 2020
Manufacturing and Laboratory Equipment \| Minimum
Property Plant And Equipment [Line Items]
Property and equipment useful life of asset	3 years
Manufacturing and Laboratory Equipment \| Maximum
Property Plant And Equipment [Line Items]
Property and equipment useful life of asset	5 years
Computer Hardware \| Minimum
Property Plant And Equipment [Line Items]
Property and equipment useful life of asset	3 years
Computer Hardware \| Maximum
Property Plant And Equipment [Line Items]
Property and equipment useful life of asset	5 years
Office Furniture and Equipment \| Minimum
Property Plant And Equipment [Line Items]
Property and equipment useful life of asset	3 years
Office Furniture and Equipment \| Maximum
Property Plant And Equipment [Line Items]
Property and equipment useful life of asset	5 years

Fair Value Measurements - Summary of Company 's Financial Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Aggregate Fair Value	$ 31,676	$ 13,359
Total short-term investments, Aggregate Fair Value	61,615	20,086
Total asset measured at fair value, Aggregate Fair Value	93,291	33,445
Fair Value, Recurring
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost	31,677	13,359
Total cash equivalents, Unrealized Gains	1
Total cash equivalents, Unrealized Losses	(2)
Total cash equivalents, Aggregate Fair Value	31,676	13,359
Total short-term investments, Amortized Cost	61,618	20,083
Total short-term investments, Unrealized Gains	3	4
Total short-term investments, Unrealized Losses	(6)	(1)
Total short-term investments, Aggregate Fair Value	61,615	20,086
Total asset measured at fair value, Amortized Cost	93,295	33,442
Total asset measured at fair value, Unrealized Gains	4	4
Total asset measured at fair value, Unrealized Losses	(8)	(1)
Total asset measured at fair value, Aggregate Fair Value	93,291	33,445
Fair Value, Recurring \| Money Market Funds
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost	15,677	12,859
Total cash equivalents, Aggregate Fair Value	15,677	12,859
Fair Value, Recurring \| Corporate Debt Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost	2,502	500
Total cash equivalents, Unrealized Losses	(2)
Total cash equivalents, Aggregate Fair Value	2,500	500
Total short-term investments, Amortized Cost	11,588	11,348
Total short-term investments, Unrealized Gains	1	2
Total short-term investments, Unrealized Losses	(1)	(1)
Total short-term investments, Aggregate Fair Value	11,588	11,349
Fair Value, Recurring \| Commercial Paper
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost	13,498
Total cash equivalents, Unrealized Gains	1
Total cash equivalents, Aggregate Fair Value	13,499
Total short-term investments, Amortized Cost	50,030	5,985
Total short-term investments, Unrealized Gains	2	2
Total short-term investments, Unrealized Losses	(5)
Total short-term investments, Aggregate Fair Value	$ 50,027	5,987
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 Measurements - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other-than-temporary impairment losses	$ 0	$ 0
Fair value assets, level 1 to level 2 transfers, amount	0
Fair value assets, level 2 to level 1 transfers, amount	0
Fair value assets, transfers into level 3	0
Fair value liabilities, level 1 to Level 2 transfers amount	0
Fair value liabilities, level 2 to Level 1 transfers amount	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 \| 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
Level 3 \| Fair Value, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in fair value	$ 2,200,000

Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
Statements of Comprehensive Loss - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Net loss	$ (27,531)	$ (37,037)
Unrealized (loss) gain on available-for-sale securities, net of tax	(7)	3
Comprehensive loss	$ (27,538)	$ (37,034)

Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash equivalents	$ 31,676	$ 13,359
Short-term investments	61,615	20,086
Assets measured at fair value	93,291	33,445
Current liabilities:
Liabilities measured at fair value		2,158
Money Market Funds
Current assets:
Cash equivalents	15,677	12,859
Corporate Debt Securities
Current assets:
Cash equivalents	2,500	500
Short-term investments	11,588	11,349
Commercial Paper
Current assets:
Cash equivalents	13,499
Short-term investments	50,027	5,987
Government Agency Bonds
Current assets:
Short-term investments		2,750
Preferred Stock Tranche Obligation
Current liabilities:
Liabilities measured at fair value		2,158
Level 1
Current assets:
Cash equivalents	15,677	12,859
Assets measured at fair value	15,677	12,859
Level 1 \| Money Market Funds
Current assets:
Cash equivalents	15,677	12,859
Level 2
Current assets:
Cash equivalents	15,999	500
Short-term investments	61,615	20,086
Assets measured at fair value	77,614	20,586
Level 2 \| Corporate Debt Securities
Current assets:
Cash equivalents	2,500	500
Short-term investments	11,588	11,349
Level 2 \| Commercial Paper
Current assets:
Cash equivalents	13,499
Short-term investments	$ 50,027	5,987
Level 2 \| Government Agency Bonds
Current assets:
Short-term investments		2,750
Level 3
Current liabilities:
Liabilities measured at fair value		2,158
Level 3 \| Preferred Stock Tranche Obligation
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	12 Months Ended
	Dec. 31, 2020 USD ($)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value as of December 31, 2019	$ 2,158
Change in fair value and expiration of the preferred stock tranche obligation	$ (2,158)

Balance Sheet Components - Schedule of Prepaid Expenses and Other Non-Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expense And Other Assets Noncurrent [Abstract]
Prepaid clinical and research expenses		$ 1,462
Deferred offering costs		894
Deposits	$ 608	58
Total prepaid expenses and other non-current assets	$ 608	$ 2,414

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 3,080	$ 2,714
Less: accumulated depreciation	(1,134)	(739)
Property and equipment, net	1,946	1,975
Manufacturing and Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	2,179	1,863
Computer Hardware
Property Plant And Equipment [Line Items]
Property and equipment, at cost	28	28
Office Furniture and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	28	28
Leasehold Improvement
Property Plant And Equipment [Line Items]
Property and equipment, at cost	234
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 611	$ 795

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Depreciation expense	$ 395	$ 303

Balance Sheet Components - Schedule of Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Liabilities Current [Abstract]
Salaries and benefits	$ 2,302	$ 2,044
Professional services	425	946
Deferred rent	27
Other	374	134
Total other current liabilities	$ 3,128	$ 3,124

Commitments and Contingencies - Schedule of Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2021	$ 658
2022	403
2023	205
Total future minimum lease payments	$ 1,266

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Summary of Outstanding Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 29, 2020	Dec. 31, 2019	Jul. 31, 2019
Temporary Equity [Line Items]
Shares Authorized			142,150,096
Shares Outstanding	0	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

Income Taxes - Schedule of Reconciliation of Federal Statutory Income Tax Rate to Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Taxes [Abstract]
Income tax benefit at the federal statutory rate	21.00%	21.00%
State income taxes, net of federal benefit	3.20%	1.10%
Research and development tax credits	1.30%	2.80%
Other	(0.60%)	(0.30%)
Mark to market gain/loss	1.70%
Change in valuation allowance	(26.60%)	(24.60%)

Income Taxes - Schedule of Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Federal and state net operating loss carryforwards	$ 27,567	$ 21,262
Research and development tax credits	4,887	4,140
Other	748	488
Gross deferred tax assets	33,202	25,890
Less: valuation allowance	(33,141)	(25,841)
Total deferred tax assets	61	49
Deferred tax liabilities
Depreciation	(61)	(49)
Total deferred tax liabilities	$ (61)	$ (49)

Income Taxes - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Income Taxes [Line Items]
Deferred tax assets increase in valuation allowance	$ 7.3
Federal net operating loss carryforwards	125.4
State NOLs	20.2
Federal
Income Taxes [Line Items]
Tax credits	$ 5.4
Operating loss carryforwards expiration beginning year	2035
Tax credit carryforwards expiration beginning year	2036
Net operating loss carryforwards, infinite life	$ 91.3
State
Income Taxes [Line Items]
Tax credits	$ 1.8
Tax credit carryforwards expiration beginning year	2036

Employee Retirement Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Contributions by employer	$ 0	$ 0

Net Loss Per Share Attributable to Common Stockholders - Additional Information (Details) - shares	1 Months Ended	12 Months Ended
	Jul. 31, 2019	Dec. 31, 2020
Series C Convertible Preferred Stock \| Maximum
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Convertible preferred stock could have been issued	17,014,902	17,014,902