0000950170-23-006795 | 10-K | XBRL Viewer

Employee Retirement Plan	12 Months Ended
Dec. 31, 2022
Retirement Benefits [Abstract]
Employee Retirement Plan	9. Employee Retirement Plan The Company maintains a 401(k) retirement savings plan (“401(k) Plan”). The 401(k) Plan allows employees to make contributions up to the maximum allowable by the IRS. The Company did not make any contributions to the 401(k) Plan on behalf of its employees in the years ended December 31, 2022 or 2021.

Employee Retirement Plan

12 Months Ended

Dec. 31, 2022

9. Employee Retirement Plan

The Company maintains a 401(k) retirement savings plan (“401(k) Plan”). The 401(k) Plan allows employees to make contributions up to the maximum allowable by the IRS. The Company did not make any contributions to the 401(k) Plan on behalf of its employees in the years ended December 31, 2022 or 2021.

- Definition

The entire disclosure for retirement benefits.

+ References

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+ Details

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [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, 2021		3,777,398		$	6.58		8.4	$	42
Granted		1,240,174		$	1.33
Exercised		—
Forfeited and Canceled		(665,132	)	$	3.94
Outstanding—December 31, 2022		4,352,440		$	5.49		7.8	$	—
Options Exercisable—December 31, 2022		2,399,117		$	5.87		7.1	$	—

Summary of Restricted Stock Units (RSUs) Activity

The following table summarizes restricted stock units (“RSUs”) activity for the year ended December 31, 2022:


	RSUs Outstanding
	Number of Restricted Stock Units			Weighted-Average Grant Date Fair Value Per Share
Balance - December 31, 2021		969,700		$	4.45
Granted		2,885,617		$	1.04
Vested		(506,219	)	$	3.44
Cancelled/forfeited		(33,482	)	$	3.73
Balance - December 31, 2022		3,315,616		$	1.65

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,
	2022	2021
Expected term (years)	5.5 - 6.1	5.1 - 6.1
Expected volatility	87% - 88%	87% - 88%
Risk-free interest rate	1.62% - 2.91%	0.84% - 1.12%
Expected dividend	—	—

Summary of Stock-Based Compensation Expense

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


	Year Ended December 31,
	2022		2021
Research and development	$	1,360	$	1,210
General and administrative		5,353		4,165
Total stock-based compensation expense	$	6,713	$	5,375

Income Taxes

12 Months Ended

Dec. 31, 2022

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 tax benefit of any such net operating loss carryforwards in the accompanying financial statements.

The effective tax rate for the years ended December 31, 2022 and 2021 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,
	2022			2021
Federal statutory income tax rate		21.0	%		21.0	%
State income taxes, net of federal benefit		(2.5	)	0.6
Research and development tax credits	1.7			1.4
Other		(5.3	)		(0.4	)
Change in valuation allowance		(14.9	)		(22.6	)
Effective income tax rate		—	%		—	%

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,
	2022			2021
Deferred tax assets
Federal and state net operating loss carryforwards	$	38,253		$	34,431
Research and development tax credits		5,071			5,408
Capitalized research and development expense		2,323			—
Other		882			1,408
Gross deferred tax assets		46,529			41,247
Less: valuation allowance		(46,529	)		(41,215	)
Total deferred tax assets		—			32
Deferred tax liabilities
Depreciation		—			(32	)
Total deferred tax liabilities		—			(32	)
Net deferred tax assets	$	—		$	—

The Company has incurred annual net operating losses in each year since inception. The Company has not reflected the tax 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, 2022 and 2021. The Company increased its valuation allowance by $5.3 million for the year ended December 31, 2022 in order to maintain a full valuation allowance against its deferred tax assets.

As of December 31, 2022, the Company had federal net operating loss carryforwards (“NOLs”) of $175.2 million and federal tax credits of $6.6 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, $141.1 million have an indefinite life. The Company also had gross state NOLs of $23.8 million and state tax credits of $0.6 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, or if the Merger will constitute a change in ownership, 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,
	2022			2021
Balance—beginning of year	$	2,090		$	1,981
Addition based on tax position related to current year		155			257
Reduction based on tax position related to prior year		(275	)		(148	)
Balance—end of year	$	1,970		$	2,090

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 has elected to include interest and penalties as a component of tax expense. During the years ended December 31, 2022 and 2021, the Company did not recognize accrued interest and penalties related to unrecognized tax benefits.

The Company files income tax returns in the U.S. federal, California, and several other tax jurisdictions. The federal and state income tax returns for all years remain subject to examination.

- 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

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+ Details

Balance Sheet Components

12 Months Ended

Dec. 31, 2022

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

4. Balance Sheet Components

Property and Equipment, net

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


	December 31,
	2022		2021
Manufacturing and laboratory equipment	$	—	$	2,511
Computer hardware		—		28
Office furniture and equipment		—		28
Leasehold improvements		—		234
Construction in progress		—		833
Total property and equipment, at cost		—		3,634
Less: accumulated depreciation		—		(1,653	)
Property and equipment, net	$	—	$	1,981

Depreciation expense for the years ended December 31, 2022 and 2021 was $0.3 million and $0.5 million, respectively. As of December 31, 2022, the Company had disposed all of its property and equipment.

Prepaid Expenses and Other Current Assets

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


	December 31,
	2022		2021
Prepaid expenses	$	503	$	1,866
Prepaid clinical and research expenses		—		168
Interest and other receivables		39		21
Other current assets		—		1,353
Total prepaid expenses and other current assets	$	542	$	3,408

Other Current Liabilities

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


	December 31,
	2022		2021
Salaries and benefits	$	698	$	2,278
Professional services		431		461
Holdback liability for acquisition of in-process research and development		250		—
Severance and termination benefits		124		—
Other		77		479
Deferred rent		—		8
Total other current liabilities	$	1,580	$	3,226

Restructuring, Impairment and Other Costs of Terminated Programs

12 Months Ended

Dec. 31, 2022

Restructuring and Related Activities [Abstract]

Restructuring, Impairment and Other Costs of Terminated Programs

6. Restructuring, Impairment and Other Costs of Terminated Programs

As discussed in Note 1, based on the conclusions from the comprehensive review of strategic alternatives focused on maximizing shareholder value, the Company decided to terminate all activities relating to the GB-102 and GB-401 programs and to reduce its workforce as a part of cost-reduction initiatives. In connection with these events, impairment of capital equipment and operating right-of-use asset of its Maryland facility, severance and termination benefit costs for employees, and other costs were recorded under restructuring, impairment and other costs of terminated programs in the consolidated statement of operations for the year ended December 31, 2022.

The Company recorded the following under restructuring, impairment and other costs (in thousands):


	Year Ended December 31,
	2022
Impairment of capital equipment and right-of-use asset	$	1,599
Severance and termination benefit expense		1,065
Other restructuring costs		299
Restructuring, impairment and other costs of terminated programs	$	2,963

Impairment of Capital Equipment and Right-of-Use Asset

In connection with the restructuring, the Company either sold or disposed of all the equipment in its Maryland facility, including equipment that had been fully depreciated. The fair value of the capital equipment was determined based on the net cash proceeds received from the sale of the equipment. Subsequently, in October 2022, the Company decommissioned and vacated the Maryland

facility and recorded an impairment charge of $0.3 million to reduce the carrying value of the right-of-use asset to zero. The Company recorded an impairment charge as follows (in thousands):


	Amount
Net book value of capital equipment before impairment	$	1,659
Less: Fair value of capital equipment		(350	)
Impairment expense for capital equipment		1,309
Impairment of right-of-use asset		290
Impairment of capital equipment and right-of-use asset	$	1,599

Severance and Termination Benefit Expense

Employees affected by the reduction-in-force are entitled to receive severance payments and certain Company-funded benefits. Severance and termination benefit expense was recorded in full for all terminated employees. As of December 31, 2022, $0.1 million in severance payments were not yet paid. The Company recorded severance and termination benefit expense as follows (in thousands):


	Total
Total severance and other termination benefits, at fair value	$	1,065

Expense recognized during the period	$	1,065
Payments during the period		(941	)
Liability balance as of December 31, 2022	$	124

Adjustments to severance and termination benefit expense may be recorded in future periods as the estimates of the costs of benefits change. However, it is not expected that such adjustments will have a material effect on the results of operations or financial condition.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

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,
	2022			2021
Federal statutory income tax rate		21.0	%		21.0	%
State income taxes, net of federal benefit		(2.5	)	0.6
Research and development tax credits	1.7			1.4
Other		(5.3	)		(0.4	)
Change in valuation allowance		(14.9	)		(22.6	)
Effective income tax rate		—	%		—	%

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,
	2022			2021
Deferred tax assets
Federal and state net operating loss carryforwards	$	38,253		$	34,431
Research and development tax credits		5,071			5,408
Capitalized research and development expense		2,323			—
Other		882			1,408
Gross deferred tax assets		46,529			41,247
Less: valuation allowance		(46,529	)		(41,215	)
Total deferred tax assets		—			32
Deferred tax liabilities
Depreciation		—			(32	)
Total deferred tax liabilities		—			(32	)
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,
	2022			2021
Balance—beginning of year	$	2,090		$	1,981
Addition based on tax position related to current year		155			257
Reduction based on tax position related to prior year		(275	)		(148	)
Balance—end of year	$	1,970		$	2,090

Stock-Based Compensation - Schedule of Assumptions Using Black-Scholes to Estimate Fair Value of Each Awards (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	87.00%	87.00%
Expected volatility, maximum	88.00%	88.00%
Risk-free interest rate, minimum	1.62%	0.84%
Risk-free interest rate, maximum	2.91%	1.12%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 6 months	5 years 1 month 6 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 years 1 month 6 days	6 years 1 month 6 days

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value Disclosures [Abstract]

Schedule of Assets Measured at Fair Value on Recurring Basis

The following tables present information about the Company’s financial assets 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, 2022
	Level 1		Level 2		Level 3		Total
Current assets:
Cash equivalents:
Money market funds	$	12,374	$	—	$	—	$	12,374
Total cash equivalents		12,374		—		—		12,374
Short-term investments:
Corporate debt securities		—		1,000		—		1,000
Commercial paper		—		17,378		—		17,378
U.S. Treasury notes		—		1,490		—		1,490
U.S. Government sponsored entities - mortgage-backed securities		—		1,956		—		1,956
Total short-term investments		—		21,824		—		21,824
Total assets measured at fair value	$	12,374	$	21,824	$	—	$	34,198


	December 31, 2021
	Level 1		Level 2		Level 3		Total
Current assets:
Cash equivalents:
Money market funds	$	8,920	$	—	$	—	$	8,920
Corporate debt securities		—		1,480		—		1,480
Commercial paper		—		2,749		—		2,749
Total cash equivalents		8,920		4,229		—		13,149
Short-term investments:
Corporate debt securities		—		1,117		—		1,117
Commercial paper		—		41,954		—		41,954
U.S. Treasury notes		—		7,235		—		7,235
Total short-term investments		—		50,306		—		50,306
Total assets measured at fair value	$	8,920	$	54,535	$	—	$	63,455

Summary of Company's Financial Assets Measured at Fair Value

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, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
Current assets:
Cash equivalents:
Money market funds	$	12,374	$	—	$	—		$	12,374
Total cash equivalents		12,374		—		—			12,374
Short-term investments:
Corporate debt securities		1,001		—		(1	)		1,000
Commercial paper		17,405		2		(29	)		17,378
U.S. Treasury notes		1,499		—		(9	)		1,490
U.S. Government sponsored entities - mortgage-backed securities		1,956		—		—			1,956
Total short-term investments		21,861		2		(39	)		21,824
Total assets measured at fair value	$	34,235	$	2	$	(39	)	$	34,198


	December 31, 2021
	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
Current assets:
Cash equivalents:
Money market funds	$	8,920	$	—	$	—		$	8,920
Corporate debt securities		1,480		—		—			1,480
Commercial paper		2,749		—		—			2,749
Total cash equivalents		13,149		—		—			13,149
Short-term investments:
Corporate debt securities		1,117		—		(1	)		1,116
Commercial paper		41,956		6		(8	)		41,954
U.S. Treasury notes		7,249		—		(13	)		7,236
Total short-term investments		50,322		6		(22	)		50,306
Total assets measured at fair value	$	63,471	$	6	$	(22	)	$	63,455

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning Balance at Dec. 31, 2020	$ 94,786	$ 2	$ 228,155	$ (133,367)	$ (4)
Beginning Balance, Shares at Dec. 31, 2020		20,979,265
Stock issued on exercise of stock options	695		695
Stock issued on exercise of stock options, Shares		353,508
Issuance of common stock upon vesting of restricted stock units, Shares		25,000
Stock-based compensation expense	5,375		5,375
Net loss	(35,821)			(35,821)
Unrealized loss on available-for-sale securities, net of tax	(12)				(12)
Ending Balance at Dec. 31, 2021	65,023	$ 2	234,225	(169,188)	(16)
Ending Balance, Shares at Dec. 31, 2021		21,357,773
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes	(139)		(139)
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, Shares		338,660
Stock-based compensation expense	6,713		6,713
Net loss	(35,605)			(35,605)
Unrealized loss on available-for-sale securities, net of tax	(21)				(21)
Ending Balance at Dec. 31, 2022	$ 35,971	$ 2	$ 240,799	$ (204,793)	$ (37)
Ending Balance, Shares at Dec. 31, 2022		21,696,433

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Lease Payments

As of December 31, 2021, future minimum commitments under the Company's non-cancelable operating leases, in accordance with ASC 840, were as follows (in thousands).


	Year Ended
	December 31,
2022	$	527
2023		205
Total future minimum lease payments	$	732

Stock-Based Compensation - Summary of Restricted Stock Units (Detail) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Restricted Stock Units, Balance \| shares	969,700
Number of Restricted Stock Units, Granted \| shares	2,885,617
Number of Restricted Stock Units, Vested \| shares	(506,219)
Number of Restricted Stock Units, Cancelled/Forfeited \| shares	(33,482)
Number of Restricted Stock Units, Balance \| shares	3,315,616
Weighted-Average Grant Date Fair Value Per Share, Balance \| $ / shares	$ 4.45
Weighted-Average Grant Date Fair Value Per Share, Granted \| $ / shares	1.04
Weighted-Average Grant Date Fair Value Per Share, Vested \| $ / shares	3.44
Weighted-Average Grant Date Fair Value Per Share, Cancelled/Forfeited \| $ / shares	3.73
Weighted-Average Grant Date Fair Value Per Share, Balance \| $ / shares	$ 1.65

Fair Value Measurements - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) Investment	Dec. 31, 2021 USD ($)
Fair Value Disclosures [Abstract]
Fair value assets, transfers amount between levels 1 and 2	$ 0
Fair value liabilities, transfers amount between levels 1 and 2	0
Fair value assets, transfers into level 3	0
Fair value liabilities, transfers into level 3	$ 0
Number of short-term investments in unrealized loss positions \| Investment	12
Other-than-temporary impairment losses	$ 0	$ 0

Balance Sheet Components - Schedule of Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Other Liabilities, Current [Abstract]
Salaries and benefits	$ 698	$ 2,278
Professional services	431	461
Holdback liability for acquisition of in-process research and development	250
Severance and termination benefits	124
Other	77	479
Deferred rent		8
Total other current liabilities	$ 1,580	$ 3,226

Commitments and Contingencies - Schedule of Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2022	$ 527
2023	205
Total future minimum lease payments	$ 732

Subsequent Events

12 Months Ended

Dec. 31, 2022

Subsequent Events [Abstract]

Subsequent Events

11. Subsequent Events

On February 10, 2023, the Company and CalciMedica entered into a note purchase agreement (the “Note Purchase Agreement”) providing for the Company to make short-term loans (the “Loan” or “Loans”) to CalciMedica up to an aggregate principal amount of $2.0 million. The Loans will bear simple interest, in arrears, at 7.5% per annum. On each of February 10 and 24, 2023, the Company purchased from CalciMedica Loans in the amount of $0.5 million for a total indebtedness of $1.0 million. CalciMedica’s ability to borrow the remaining $1.0 million under the Note Purchase Agreement is subject to certain conditions and restrictions on use.

In connection with the Note Purchase Agreement, on February 10, 2023, Graybug, CalciMedica and Camaro Merger Sub, Inc. entered into a First Amendment to the Merger Agreement, pursuant to which the parties agreed that the amount of any outstanding principal and accrued interest under the Loans will be included in the calculation of Graybug’s net cash at the closing of the Merger.

Fair Value Measurements

12 Months Ended

Dec. 31, 2022

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.


	December 31, 2022
	Level 1		Level 2		Level 3		Total
Current assets:
Cash equivalents:
Money market funds	$	12,374	$	—	$	—	$	12,374
Total cash equivalents		12,374		—		—		12,374
Short-term investments:
Corporate debt securities		—		1,000		—		1,000
Commercial paper		—		17,378		—		17,378
U.S. Treasury notes		—		1,490		—		1,490
U.S. Government sponsored entities - mortgage-backed securities		—		1,956		—		1,956
Total short-term investments		—		21,824		—		21,824
Total assets measured at fair value	$	12,374	$	21,824	$	—	$	34,198


	December 31, 2021
	Level 1		Level 2		Level 3		Total
Current assets:
Cash equivalents:
Money market funds	$	8,920	$	—	$	—	$	8,920
Corporate debt securities		—		1,480		—		1,480
Commercial paper		—		2,749		—		2,749
Total cash equivalents		8,920		4,229		—		13,149
Short-term investments:
Corporate debt securities		—		1,117		—		1,117
Commercial paper		—		41,954		—		41,954
U.S. Treasury notes		—		7,235		—		7,235
Total short-term investments		—		50,306		—		50,306
Total assets measured at fair value	$	8,920	$	54,535	$	—	$	63,455

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 investments is determined from market pricing and other observable market inputs for similar securities obtained from various third-party data providers. These 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.

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


	December 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
Current assets:
Cash equivalents:
Money market funds	$	12,374	$	—	$	—		$	12,374
Total cash equivalents		12,374		—		—			12,374
Short-term investments:
Corporate debt securities		1,001		—		(1	)		1,000
Commercial paper		17,405		2		(29	)		17,378
U.S. Treasury notes		1,499		—		(9	)		1,490
U.S. Government sponsored entities - mortgage-backed securities		1,956		—		—			1,956
Total short-term investments		21,861		2		(39	)		21,824
Total assets measured at fair value	$	34,235	$	2	$	(39	)	$	34,198


	December 31, 2021
	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
Current assets:
Cash equivalents:
Money market funds	$	8,920	$	—	$	—		$	8,920
Corporate debt securities		1,480		—		—			1,480
Commercial paper		2,749		—		—			2,749
Total cash equivalents		13,149		—		—			13,149
Short-term investments:
Corporate debt securities		1,117		—		(1	)		1,116
Commercial paper		41,956		6		(8	)		41,954
U.S. Treasury notes		7,249		—		(13	)		7,236
Total short-term investments		50,322		6		(22	)		50,306
Total assets measured at fair value	$	63,471	$	6	$	(22	)	$	63,455

As of December 31, 2022 and 2021, 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. The Company had 12 short-term investments in unrealized loss positions as of December 31, 2022. The Company’s unrealized losses from short-term investments as of December 31, 2022 were caused by interest rate increases and not by unfavorable changes in the credit quality associated with these securities. The Company does not intend to sell short-term investments that are in an unrealized loss position, and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost basis, which may be maturity. Therefore, the Company believes these losses to be temporary and as a result, did not recognize any other-than-temporary impairment losses as of December 31, 2022 and 2021.

Net Loss Per Share

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Net Loss Per Share

10. Net Loss Per Share

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


	Year Ended December 31,
	2022			2021
Net loss	$	(35,605	)	$	(35,821	)
Net loss per share—basic and diluted	$	(1.66	)	$	(1.69	)
Weighted-average number of shares used in computing net loss per share—basic and diluted		21,489,280			21,199,291

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


	As of December 31,
	2022		2021
Stock options to purchase common stock		4,352,440		3,777,398
Restricted stock units		3,315,616		969,700
Warrants to purchase common stock		27,759		27,759

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 3,634
Less: accumulated depreciation	(1,653)
Property and equipment, net	1,981
Manufacturing and Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	2,511
Computer Hardware
Property Plant And Equipment [Line Items]
Property and equipment, at cost	28
Office Furniture and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	28
Leasehold Improvements
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	$ 833

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 503	$ 1,866
Prepaid clinical and research expenses		168
Interest and other receivables	39	21
Other current assets		1,353
Total prepaid expenses and other current assets	$ 542	$ 3,408

Summary of Significant Accounting Policies - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 Segment	Jan. 01, 2022 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segment \| Segment	1
Operating lease right-of-use asset		$ 0.6
Operating lease liabilities		$ 0.6
Accounting Standards Update 2016-02
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2022
Change in accounting principle, accounting standards update, immaterial effect	true
Accounting Standards Update 2019-12
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2022
Change in accounting principle, accounting standards update, immaterial effect	true

- Definition

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

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Net Loss Per Share - Schedule of Basic and Diluted Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net loss	$ (35,605)	$ (35,821)
Net loss per share-basic	$ (1.66)	$ (1.69)
Net loss per share-diluted	$ (1.66)	$ (1.69)
Weighted-average number of shares used in computing net loss per share-basic	21,489,280	21,199,291
Weighted-average number of shares used in computing net loss per share-diluted	21,489,280	21,199,291

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

5. Commitments and Contingencies

The Company has historically entered into contracts in the normal course of business with CDMOs, for manufacturing process development and preclinical/clinical supply manufacturing, and with other vendors for preclinical research studies and other services or products for operating purposes. These contracts generally provide for termination on notice of 60 to 90 days. As of December 31, 2022, there was one such contract, worth approximately $1.3 million, still in effect for future services, and there were no unpaid cancellation or other related costs.

In connection with the Company’s agreement with an investment banking firm for services related to the proposed Merger with CalciMedica, the Company incurred and paid approximately $0.8 million during the current year and will be required to make an additional payment of approximately $2.3 million contingent upon the consummation of the proposed Merger with CalciMedica. The $0.8 million incurred during the current year is included in general and administrative expenses.

In connection with the proposed Merger with CalciMedica, all outstanding stock awards will be fully accelerated and the Company will be required to make change-in-control severance payments to its current employees totaling approximately $5.5 million.

As of December 31, 2022, these commitments were approximately $9.1 million due within 3 to 6 months.

Operating Lease Agreements

The Company leases a facility in Baltimore, Maryland under an operating lease with a term through June 2023. The Company also had a short-term lease for approximately 2,560 rentable square feet of office space in Redwood City, California, which was amended in December 2022 to extend the term from August 31, 2022 to January 31, 2023, at which time it expired. The operating cash outflow for the Maryland lease liability was $0.4 million for the year ended December 31, 2022. The remaining term of the Maryland lease was 0.5 years, and the incremental borrowing rate used to determine the operating lease liability was 6.0%.

In the fourth quarter of 2022, following the sale of all equipment in the facility in connection with the restructuring (see Note 6), the Company decommissioned and vacated the Maryland facility and recorded an impairment charge to reduce the carrying value of the right-of-use asset to zero.

Lease expense recognized for the operating leases, including short-term leases not included in the measurement of the lease liability, was $0.5 million for the year ended December 31, 2022. Under the terms of the lease agreements, the Company is also responsible for certain variable lease payments that are not included in the measurement of the lease liability. Variable lease payments

for the operating leases were $0.5 million for the year ended December 31, 2022. Rent expense recognized under ASC 840 for the year ended December 31, 2021 was $0.7 million.

As of December 31, 2022, the Company's remaining future minimum lease payments were $0.2 million.

As of December 31, 2021, future minimum commitments under the Company's non-cancelable operating leases, in accordance with ASC 840, were as follows (in thousands).


	Year Ended
	December 31,
2022	$	527
2023		205
Total future minimum lease payments	$	732

License Agreements

Johns Hopkins University

In June 2011, the Company entered into an Exclusive License Agreement with Johns Hopkins University (“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 would not grant a license to know how and materials to any other commercial entity.

The JHU Agreement was only relevant to our GB-102 and GB-103 programs, both of which had been terminated by August 2022. On October 3, 2022, the Company provided written notification to JHU of complete termination of the exclusive license agreement to all licensed patent rights owned by JHU.

Asset Acquisition & Divestiture

In December 2021, the Company entered into an Assignment and Licensing Agreement with a private company, pursuant to which the Company acquired certain intellectual property rights, including patents and know-how, related to new cyclic monophosphate (“cGMP”) compounds for the treatment of ocular disorders.

As consideration for the intellectual property rights acquired, the Company made an upfront cash payment of $0.5 million and may be required to make additional contingent payments of up to $27.0 million in the aggregate upon achievement of certain development and regulatory milestones. Additionally, upon commercialization, the Company would have been required to make tiered single-digit royalty payments based on net product sales.

As the acquired rights related to in-process research and development activities that had no alternative future use to the Company, the upfront payment of $0.5 million was recorded as research and development expense in the accompanying consolidated statements of operations for the year ended December 31, 2021. In November 2022, this Assignment and Licensing Agreement was terminated, and all rights were returned to the licensor. Accordingly, as of December 31, 2022, the Company had no further obligation to pay development or regulatory milestones and, accordingly, no amounts have been recognized in the accompanying consolidated financial statements with respect to these contingent payments.

RainBio Asset Acquisition

In March 2022, the Company acquired RainBio, a private company in the United States whose primary assets are certain gene therapy technology and preclinical data (“GB-501”). RainBio was purchased at a cost of approximately $2.2 million, including transaction costs and a contingent holdback, and the Company may be required to make additional contingent payments of up to $17.5 million in the aggregate upon the achievement of certain milestones. Other than the contingent holdback release, no further payments are required until FDA approval of a product based upon the acquired assets and the sale or utilization of any priority review voucher that may be granted in connection with such approval. The contingent holdback liability of $0.3 million was recorded in other current liabilities in the consolidated balance sheets.

The acquisition was accounted for as an asset acquisition, as substantially all of the fair value of the assets acquired was concentrated in a single in-process research and development (“IPR&D”) intangible asset. As the acquired IPR&D did not have an alternative future use to the Company, the purchase price of $2.2 million was recorded as research and development expense in the accompanying consolidated statement of operations for the year ended December 31, 2022. As of December 31, 2022, none of the milestones were probable of achievement and, accordingly, no amounts have been recognized in the accompanying consolidated financial statements with respect to these contingent payments.

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.

Litigation

The Company is a party to legal proceedings and claims which have arisen during the ordinary course of business. The Company is not presently a party to any legal proceedings that, in the opinion of management, would have a material adverse effect on its business. The Company has been served with four complaints asserting that certain disclosures in the proxy statement filed by the Company with the Securities and Exchange Commission on December 14, 2022, in connection with the Merger, are inadequate. These complaints do not currently seek monetary damages. The Company reviews its legal proceedings and claims, regulatory reviews and inspections, and other legal matters on an ongoing basis and follow appropriate accounting guidance when making accrual and disclosure decisions. For all currently unresolved legal proceedings or claims, the Company does not believe there is a reasonable probability that any material loss will be incurred. Accordingly, no material accrual or disclosure of a potential range of loss has been made related to these matters. The Company does not expect the ultimate liability of these unresolved legal proceedings or claims to have a material effect on its financial position, liquidity or capital resources.

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating activities:
Net loss	$ (35,605)	$ (35,821)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	6,713	5,375
Depreciation	338	519
Loss on sale/disposal of assets	97
Noncash lease expense	277
Accretion of premium and discounts on short-term investments	(319)	58
Acquired in-process research and development	2,194
Impairment of capital equipment and right-of-use asset	1,599
Changes in operating assets and liabilities:
Prepaid expenses and other current and non-current assets	2,895	1,378
Accounts payable	1,304	(2,052)
Accrued research and development	(104)	(1,052)
Operating lease liability	(380)
Other current and non-current liabilities	(1,888)	95
Net cash used in operating activities	(22,879)	(31,500)
Investing activities:
Purchases of property and equipment	(308)	(488)
Purchases of investments	(35,569)	(94,570)
Maturity of investments	64,349	105,809
Acquisition of in-process research and development	(1,944)
Proceeds from sale of property and equipment	430
Net cash provided by investing activities	26,958	10,751
Financing activities:
Payment of taxes on vested restricted stock units	(139)
Proceeds from exercise of stock options		695
Net cash (used in) provided by financing activities	(139)	695
Net increase (decrease) in cash and cash equivalents	3,940	(20,054)
Cash and cash equivalents at beginning of period	13,364	33,418
Cash and cash equivalents at end of period	17,304	13,364
Supplemental disclosure of noncash items:
Right-of-use asset arising from the adoption of ASC 842	567
Acquired in process research and development in accrued liabilities	$ 250
Unpaid balance for purchases of property and equipment		$ 115

Commitments and Contingencies - Additional Information (Details)	1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) ft² Contract	Dec. 31, 2022 USD ($) ft² Contract	Dec. 31, 2021 USD ($)	Dec. 14, 2022 Complaint	Jan. 01, 2022 USD ($)
Loss Contingencies [Line Items]
Contractual obligation		$ 9,100,000	$ 9,100,000
Number of contract currently in effect \| Contract		1	1
Contractual obligation of contract in effect		$ 1,300,000	$ 1,300,000
Unpaid cancellation and other related costs			0
Lease expense			500,000
Variable lease payments			500,000
Operating lease liabilities						$ 600,000
Contingent holdback liabilities		250,000	250,000
Development or regulatory milestones were deemed probable of achievement			0
Contingent payments recognized			0
Number of litigation complaints \| Complaint					4
Acquired in-process research and development			2,194,000
Accounting Standards Update 2016-02
Loss Contingencies [Line Items]
Lease expense				$ 700,000
CalciMedica
Loss Contingencies [Line Items]
Amount incurred and paid upon Merger related services			800,000
Additional payment of Merger Related costs contingent upon the consummation of the proposed Merger			2,300,000
Severance payments upon merger		$ 5,500,000	5,500,000
Mireca Medicines GmbH
Loss Contingencies [Line Items]
Upfront cash payment made				500,000
Additional contingent payments upon achievement of certain development and regulatory milestone				27,000,000.0
Contingent payments recognized			$ 0
RainBio
Loss Contingencies [Line Items]
Additional contingent payments upon achievement of certain development and regulatory milestone	$ 17,500,000
Contingent holdback liabilities	300,000
Private company purchase cost including estimated transaction costs and contingent holdback	$ 2,200,000
Baltimore, Maryland
Loss Contingencies [Line Items]
Operating lease, term			2023-06
Cash paid for operating leases			$ 400,000
Operating lease remaining term		6 months	6 months
Operating lease incremental borrowing rate, percentage		6.00%	6.00%
Impairment charge to reduce the carrying value of the right-of-use asset		$ 0
Operating lease liabilities		$ 200,000	$ 200,000
Redwood City, California
Loss Contingencies [Line Items]
Area of office space \| ft²		2,560	2,560
Short term operating lease expiration date			Aug. 31, 2022
Extended short term operating lease expiration date			Jan. 31, 2023
Research and Development \| Mireca Medicines GmbH
Loss Contingencies [Line Items]
Upfront cash payment made				$ 500,000
General and Administrative \| CalciMedica
Loss Contingencies [Line Items]
Amount incurred and paid upon Merger related services			$ 800,000
Minimum
Loss Contingencies [Line Items]
Contractual obligation term			3 months
Maximum
Loss Contingencies [Line Items]
Contractual obligation term			6 months

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
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	500,000,000
Common stock, shares issued	21,696,433	21,357,773
Common stock, shares outstanding	21,696,433	21,357,773

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2022

Balance Sheet Related Disclosures [Abstract]

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,
	2022		2021
Manufacturing and laboratory equipment	$	—	$	2,511
Computer hardware		—		28
Office furniture and equipment		—		28
Leasehold improvements		—		234
Construction in progress		—		833
Total property and equipment, at cost		—		3,634
Less: accumulated depreciation		—		(1,653	)
Property and equipment, net	$	—	$	1,981

Schedule of Prepaid Expenses and Other Current Assets

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


	December 31,
	2022		2021
Prepaid expenses	$	503	$	1,866
Prepaid clinical and research expenses		—		168
Interest and other receivables		39		21
Other current assets		—		1,353
Total prepaid expenses and other current assets	$	542	$	3,408

Schedule of Other Current Liabilities

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


	December 31,
	2022		2021
Salaries and benefits	$	698	$	2,278
Professional services		431		461
Holdback liability for acquisition of in-process research and development		250		—
Severance and termination benefits		124		—
Other		77		479
Deferred rent		—		8
Total other current liabilities	$	1,580	$	3,226

Restructuring, Impairment and Other Costs of Terminated Programs - Schedule of Recorded Impairment Charges (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Restructuring and Related Activities [Abstract]
Net book value of capital equipment before impairment	$ 1,659
Less: Fair value of capital equipment	350
Impairment expense for capital equipment	1,309
Impairment of right-of-use asset	290
Impairment of capital equipment and right-of-use asset	$ 1,599

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and are 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 (“ASC”) and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”).

The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiary, RainBio, Inc. (“RainBio”), which was acquired in March 2022 (see Note 5). All intercompany balances and transactions have been eliminated in consolidation.

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. Significant items subject to estimates include estimates related to accrued research and development expenses, contingent milestone payments, other long-lived assets, stock-based compensation, incremental borrowing rates for leases and the valuation of deferred tax assets. 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.

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 consist of money market fund investments, corporate debt securities, and commercial paper.

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) on debt securities in accumulated other comprehensive loss, a component of stockholders’ equity. 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.

The Company periodically evaluates whether declines in fair values of its marketable securities below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the marketable security until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any marketable securities before recovery of its amortized cost basis. Impairment assessments are made at the individual security level each reporting period. When the fair value of an available-for-sale security is less than its cost at the balance sheet date, a determination is made as to whether the impairment is other-than-temporary and, if it is other-than-temporary, an impairment loss is recognized in the statements of operations, equal to the difference between the investment’s amortized cost and fair value at such date. The Company did not record any impairment charges related to its marketable securities during the years ended December 31, 2022 and 2021. All investment transactions are recorded on a trade date basis.

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, 2022 and 2021 mature in less than 12 months and are included in short-term investments in the consolidated 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, 2022 and 2021, 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.

Property and Equipment

Property and equipment are stated at cost, subject to adjustments for impairments, less accumulated depreciation. 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 were 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.

Leases

The Company adopted Accounting Standards Codification (“ASC”), Topic 842, Leases (“ASC 842”), on January 1, 2022, as discussed below in Recently Adopted Accounting Pronouncements. Under ASC 842, the Company determines if an arrangement is or contains a lease at contract inception.

Operating lease right-of-use assets represent the Company’s right and ability to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized based on the present value of lease payments over the lease term at the commencement date of the lease. Right-of-use assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement

date, less any lease incentive received. The present value of lease payments is determined by using the interest rate implicit in the lease, if that rate is readily determinable; otherwise, the Company uses its incremental borrowing rate. The incremental borrowing rate reflects the rate of interest that a lessee would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. Lease expense for an operating lease is recognized on a straight-line basis over the lease term.

The Company elected the practical expedient to not separate lease and non-lease components for all classes of assets. Additionally, the Company has elected an accounting policy to not recognize short-term leases, which have a lease term of 12 months or less, on the condensed consolidated balance sheet. Variable lease payments are primarily related to utilities, property taxes, insurance and common area maintenance, and are recognized as lease cost when incurred.

Restructuring, Impairment and Other Costs of Terminated Programs

Restructuring, impairment and other costs of terminated programs primarily consists of severance and termination benefit expense and non-cash impairment of capital equipment and an operating lease right-of-use asset. These charges are included in restructuring, impairment and other costs of terminated programs in the condensed consolidated statement of operations.

The Company recognizes severance and termination benefits when it is probable that employees will be entitled to such benefits and the amount can be reasonably estimated and recorded at fair value. The timing of the recognition of expense for severance and termination benefits depends on whether employees are required to render service until they are terminated in order to receive the termination benefits. If employees are required to render service until they are terminated in order to receive the severance and termination benefits, a liability is recognized ratably over the future service period. Otherwise, a liability is recognized when management has committed to a restructuring plan and has communicated those actions to affected employees.

Refer to Note 6 for additional information on the severance expense that the Company recognized for employees terminated in connection with the August 2022 reduction-in-force.

Long-lived Asset Impairment

The Company assesses long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amounts of the asset or group of assets may not be recoverable. During the year ended December 31, 2022, the Company commenced restructuring activities which indicated that the carrying amount of the long-lived assets might not be recoverable. The Company evaluated the long-lived assets, consisting primarily of capital equipment and an operating lease right-of-use asset, for impairment. If the carrying amount of an asset group exceeds its estimated undiscounted net future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset group exceeds its fair value. To the extent available, the Company will also consider third-party valuations of an asset group that were prepared for other business purposes. An impairment charge is recognized for the amount by which the carrying value exceeds its estimated fair value. When an impairment loss is recognized for equipment to be held and used, the adjusted carrying amounts are depreciated over their remaining useful life.

All of the Company’s equipment in its Maryland facility was sold during the year ended December 31, 2022. Additionally, the Company decommissioned the facility in the fourth quarter and all employees that had worked in that facility were either terminated or permanently working remotely as of December 31, 2022. As such, the Company recorded an impairment charge to reflect the net cash proceeds received from the sale of the equipment, and an impairment charge of the operating lease right-of-use asset related to the Maryland facility. Refer to Note 6 for additional information regarding the impairment charges recorded in connection with the Company’s restructuring.

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 development and manufacturing organizations (“CDMOs”) contract research organizations (“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. The Company’s clinical and manufacturing development activities have been conducted by third-party service providers, including CROs and CDMOs. 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.

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 consolidated 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 (“Black-Scholes”). The valuation of restricted stock units (“RSUs”), is determined at the date of grant using the Company’s closing stock price on that date. 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

Basic net loss per share is computed by dividing the net loss 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 and RSUs. Likewise, adjustments to the denominator are required to reflect the related dilutive shares. In all periods presented, the Company’s outstanding stock options, RSUs, and warrants were excluded from the calculation of diluted net loss per share because their effects were antidilutive.

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 (“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 comprises changes in unrealized (loss) gain on available-for-sale securities.

Recently Adopted Accounting Pronouncements

In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842), as amended, 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 adopted this standard on January 1, 2022, using the modified retrospective method by applying the new standard to all leases existing as of the effective date and not restating comparative periods. The Company elected the “package of practical expedients”, which permits the Company to not reassess under this standard its prior conclusions about lease identification, lease classification and initial direct costs, as well as the practical expedient to not separate lease and non-lease components for its real estate leases. In addition, the Company elected the short-term lease recognition exemption for all leases that qualify. The impact of adoption and additional disclosures required by the standard have been included in Note 2 - Summary of Significant Accounting Policies above and in Note 5 - Commitments and Contingencies. As a result of the adoption of the new lease accounting guidance, the Company recognized, on January 1, 2022, operating lease right-of-use asset of $0.6 million and operating lease liability of $0.6 million in the consolidated balance sheet. Prior period amounts before January 1, 2022 have not been adjusted and continue to be reported in accordance with the Company’s historical accounting under previous lease guidance, ASC Topic 840, Leases (“ASC 840”).

In December 2019, the FASB issued ASU 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 adopted ASU 2019-12 on January 1, 2022, and the adoption did not have a material impact on the consolidated financial statements.

Recently Issued Accounting Pronouncements

In June 2016, the FASB issued ASU 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 consolidated financial statements and financial statement disclosures.

Income Taxes - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Income Taxes [Line Items]
Deferred tax assets increase in valuation allowance	$ 5.3
Federal net operating loss carryforwards	175.2
State NOLs	23.8
Federal
Income Taxes [Line Items]
Tax credits	$ 6.6
Operating loss carryforwards expiration beginning year	2035
Tax credit carryforwards expiration beginning year	2036
Net operating loss carryforwards, infinite life	$ 141.1
State
Income Taxes [Line Items]
Tax credits	$ 0.6
Tax credit carryforwards expiration beginning year	2036

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2022	Mar. 03, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
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		21,997,030
Entity File Number	001-39538
Entity Tax Identification Number	45-2120079
Entity Address, Address Line One	274 Redwood Shores Parkway
Entity Address, Address Line Two	P.O. Box 144
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	487-2805
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			$ 13.0
ICFR Auditor Attestation Flag	false
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	San Mateo, California
Documents Incorporated by Reference	Portions of the registrant’s Definitive Proxy Statement relating to the 2022 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, 2022. 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.

Subsequent Events - Additional Information (Details) - Subsequent Event [Member] $ in Millions	Feb. 10, 2023 USD ($)
Subsequent Event [Line Items]
Subsequent Event, Date	Feb. 10, 2023
CalciMedica, Inc.
Subsequent Event [Line Items]
Aggregate principal amount	$ 2.0
Interest rate	7.50%
Total indebtedness amount	$ 1.0
Debt instrument, purchase amount	0.5
Remaining Borrowing Capacity	$ 1.0

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Net loss	$ (35,605)	$ (35,821)
Unrealized loss on available-for-sale securities, net of tax	(21)	(12)
Comprehensive loss	$ (35,626)	$ (35,833)

- Definition

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

+ References

+ Details

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Number of Options, Outstanding	3,777,398
Number of Options, Granted	1,240,174
Number of Options, Forfeited and Canceled	(665,132)
Number of Options, Outstanding	4,352,440	3,777,398
Number of Options, Options Exercisable	2,399,117
Weighted Average Exercise Price, Outstanding	$ 6.58
Weighted Average Exercise Price, Granted	1.33
Weighted Average Exercise Price, Forfeited and Canceled	3.94
Weighted Average Exercise Price, Outstanding	5.49	$ 6.58
Weighted Average Exercise Price, Options Exercisable	$ 5.87
Weighted Average Remaining Contractual Term, Outstanding	7 years 9 months 18 days	8 years 4 months 24 days
Weighted Average Remaining Contractual Term, Options Exercisable	7 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding		$ 42

Restructuring, Impairment and Other Costs of Terminated Programs (Tables)

12 Months Ended

Dec. 31, 2022

Restructuring and Related Activities [Abstract]

Schedule of Restructuring, Impairment and Other Costs

The Company recorded the following under restructuring, impairment and other costs (in thousands):


	Year Ended December 31,
	2022
Impairment of capital equipment and right-of-use asset	$	1,599
Severance and termination benefit expense		1,065
Other restructuring costs		299
Restructuring, impairment and other costs of terminated programs	$	2,963

Schedule of Recorded Impairment Charges

facility and recorded an impairment charge of $0.3 million to reduce the carrying value of the right-of-use asset to zero. The Company recorded an impairment charge as follows (in thousands):


	Amount
Net book value of capital equipment before impairment	$	1,659
Less: Fair value of capital equipment		(350	)
Impairment expense for capital equipment		1,309
Impairment of right-of-use asset		290
Impairment of capital equipment and right-of-use asset	$	1,599

Severance and termination Benefits Over the Service Period


	Total
Total severance and other termination benefits, at fair value	$	1,065

Expense recognized during the period	$	1,065
Payments during the period		(941	)
Liability balance as of December 31, 2022	$	124

Net Loss Per Share - Schedule of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Stock Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	4,352,440	3,777,398
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	3,315,616	969,700
Warrants to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	27,759	27,759

Stock-Based Compensation - Additional Information (Details) $ / shares in Units, $ in Millions		1 Months Ended	12 Months Ended
	Jan. 14, 2022 Employee $ / shares shares	Aug. 31, 2020 shares	Dec. 31, 2022 USD ($) Employee $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Jun. 30, 2022 shares	Mar. 31, 2022 shares	Jan. 01, 2021 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate number of shares issued			21,696,433	21,357,773
Options granted			1,240,174
Common stock at an exercise price \| $ / shares			$ 1.33
Aggregate intrinsic value of options exercised \| $			$ 0.0	$ 2.5
Weighted-average grant date fair value per option granted \| $ / shares			$ 0.96	$ 2.72
Total unrecognized stock-based compensation expenses related to outstanding unvested stock awards \| $			$ 11.5
Total unrecognized stock-based compensation expenses related to outstanding unvested stock options weighted-average term of recognition			2 years 2 months 12 days
RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate grant date fair value of RSUs vested \| $			$ 1.7
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	593,887
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
Common stock additional aggregate number of shares reserved					2,340,000	1,067,888	1,048,963
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	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			2,100,000
Increase in number of shares reserved			0
Number of employee stock purchase plan \| Employee			0
Inducement Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of newly hired employees \| Employee	6
Options granted	234,200
Common stock at an exercise price \| $ / shares	$ 1.55
Number of terminated employees \| Employee	6

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 338	$ 519

Stock-Based Compensation

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [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 (the “2020 Plan”) that became effective in connection with the IPO, and serves as the successor to the Company’s 2015 Stock Incentive Plan (“2015 Plan”). The Company’s 2020 Plan authorizes the award of stock options, restricted stock units (“RSUs”) restricted stock awards (“RSAs”) stock appreciation rights (“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 5% of the aggregate number of outstanding shares of the Company’s common stock as of the immediately preceding December 31, or a lesser 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. On January 1, 2021, the aggregate number of shares reserved for issuance was increased by an additional 1,048,963 shares pursuant to the automatic share reserve increase provision of the 2020 Plan.

In March 2022, the Company increased the aggregate number of shares reserved for issuance by an additional 1,067,888 shares pursuant to the automatic share reserve increase provision of the 2020 Plan and in June 2022, the Company reserved an additional 2,340,000 shares for future issuance under the 2020 Plan following approval by the Company’s stockholders. As of December 31, 2022, there were 593,887 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 (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 initially reserved 210,000 shares of its common stock for sale under the ESPP. Per the terms of 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. The Company’s board of directors have determined that there should be no increase in the number of shares reserved for the ESPP. Accordingly, as of December 31, 2022, there were 210,000 shares available for issuance under the ESPP. There have been no employee withholdings for the purchase of shares under the plan as of December 31, 2022.

Inducement Grants

On January 14, 2022, six newly-hired employees were granted inducement options to purchase an aggregate of 234,200 shares of the Company’s common stock at an exercise price of $1.55 per share. These inducement grants were made outside of the 2020 Equity Incentive Plan in accordance with the Nasdaq Listing Rule 5635(c)(4). All six employees have since been terminated in connection with the Company’s August 2022 reduction-in-force, which was prior to the first vesting date, resulting in the forfeiture of all such inducement grants.

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, 2021		3,777,398		$	6.58		8.4	$	42
Granted		1,240,174		$	1.33
Exercised		—
Forfeited and Canceled		(665,132	)	$	3.94
Outstanding—December 31, 2022		4,352,440		$	5.49		7.8	$	—
Options Exercisable—December 31, 2022		2,399,117		$	5.87		7.1	$	—

At December 31, 2022, 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, 2022 and 2021 was zero and $2.5 million, respectively.

Restricted Stock Units

The following table summarizes restricted stock units (“RSUs”) activity for the year ended December 31, 2022:


	RSUs Outstanding
	Number of Restricted Stock Units			Weighted-Average Grant Date Fair Value Per Share
Balance - December 31, 2021		969,700		$	4.45
Granted		2,885,617		$	1.04
Vested		(506,219	)	$	3.44
Cancelled/forfeited		(33,482	)	$	3.73
Balance - December 31, 2022		3,315,616		$	1.65

The fair value of RSUs is determined on the date of grant based on the market price of the Company’s common stock on that date. The aggregate grant date fair value of RSUs vested during the year ended December 31, 2022 was $1.7 million.

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, 2022 and 2021 was $0.96 and $2.72, respectively. The fair value of each award is estimated using Black-Scholes based on the following assumptions:


	Year Ended December 31,
	2022	2021
Expected term (years)	5.5 - 6.1	5.1 - 6.1
Expected volatility	87% - 88%	87% - 88%
Risk-free interest rate	1.62% - 2.91%	0.84% - 1.12%
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,
	2022		2021
Research and development	$	1,360	$	1,210
General and administrative		5,353		4,165
Total stock-based compensation expense	$	6,713	$	5,375

As of December 31, 2022, the total unrecognized stock-based compensation expense related to outstanding unvested stock awards that are expected to vest was $11.5 million, which the Company expects to recognize over an estimated weighted-average term of 2.2 years.

Summary of Significant Accounting Policies - Schedule of Depreciation Calculated using Straight-line Method over useful Life of Asset (Details)	12 Months Ended
	Dec. 31, 2022
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

Restructuring, Impairment and Other Costs of Terminated Programs - Schedule of Restructuring, Impairment and Other Costs (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Restructuring and Related Activities [Abstract]
Impairment of capital equipment and right-of-use asset	$ 1,599
Severance and termination benefit expense	1,065
Other restructuring costs	299
Restructuring, impairment and other costs of terminated programs	$ 2,963

Employee Retirement Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Contributions by employer	$ 0	$ 0

Organization

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization

1. Organization

Graybug Vision, Inc., the Company or Graybug, has historically been a clinical-stage biopharmaceutical company developing medicines for the treatment of diseases of the retina and optic nerve. On June 28, 2022, the Company announced that it would conduct a comprehensive review of strategic alternatives focused on maximizing shareholder value. As part of this review of strategic alternatives, the Company explored the potential for an acquisition, company sale, merger, divestiture of assets, private placement of equity securities and other strategic transactions. Prior to this announcement, the Company had devoted substantially all of its resources to conducting research and development and raising capital. On August 18, 2022, the Company’s board of directors approved the restructuring plan that is described further in Restructuring below. On November 21, 2022, the Company entered into a definitive Agreement and Plan of Merger and Reorganization that is described further in Merger below. The Company was founded in May 2011 and had maintained facilities in Baltimore, Maryland and Redwood City, California. The Baltimore facility was vacated and decommissioned on October 1, 2022, and the Redwood City facility lease expired on January 31, 2023.

The Company has historically been 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.

Restructuring

On August 18, 2022, the Company’s board of directors approved certain strategic, operational and organizational steps for the Company to undertake in connection with its announcement on June 28, 2022 that the Company would conduct a comprehensive review of strategic alternatives focused on maximizing shareholder value. These steps included both the termination of all activities relating to the Company’s GB-102 and GB-401 programs and certain cost-reduction initiatives, including a reduction in its workforce by 71%. While clinical development of GB-501 remains on hold, preclinical work is still proceeding. Work on GB-701 is still in the drug discovery stage.

In connection with these actions, the Company recorded a restructuring charge of $3.0 million during the year ended December 31, 2022. The restructuring charge includes: (i) severance and termination benefit expense for 20 employees terminated with separation dates between August 31, 2022 and October 31, 2022, (ii) charges related to the impairment of research and development equipment in its Baltimore, Maryland facility and the right-of-use asset for that facility that was decommissioned in October 2022, and (iii) costs to wind-down the GB-102 and GB-401 clinical development programs. Refer to Note 6 for additional information on the restructuring.

Merger

On November 21, 2022, the Company entered into an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”) with CalciMedica, Inc. (“CalciMedica”) a clinical-stage biopharmaceutical company focused on developing first-in-class therapies for serious inflammatory diseases with high unmet need, and Camaro Merger Sub, Inc., Graybug's wholly-owned subsidiary (“Merger Sub”). Upon the terms and subject to the satisfaction of the conditions described in the Merger Agreement, Merger Sub will be merged with and into CalciMedica, with CalciMedica surviving such merger as a wholly owned subsidiary of Graybug (the “Merger”).

The Merger, which has been approved by the Company's board of directors and the board of directors and stockholders of CalciMedica, is expected to close in the first quarter of 2023, subject to the satisfaction or waiver of certain closing conditions, including the approval of the Company's stockholders. Although the Company has entered into the Merger Agreement and intends to consummate the proposed Merger, there is no assurance that the Company will be able to successfully consummate the proposed Merger on a timely basis, or at all. If, for any reason, the proposed Merger is not completed, the Company will reconsider its strategic alternatives and could pursue another strategic transaction similar to the proposed Merger, potential collaborative, partnering or other strategic arrangements for its programs, including a sale or divestiture of the Company's remaining programs, or liquidate and distribute available cash.

Going Concern Considerations

The Company incurred losses from operations and had negative cash flows from operating activities since inception, and the Company’s accumulated deficit at December 31, 2022 was $204.8 million. If the Merger fails to close, the Company expects that it would continue to incur losses from operations and generate negative cash flows from operating activities, given expenditures related to the research and development that would be required and the Company’s lack of revenue-generating activities at this point in the Company’s life cycle. Even if the Merger failed to close and the Company’s remaining product development efforts were successful, it is uncertain when, if ever, the Company would realize significant revenue from product sales.

In March 2021, the Company decided not to proceed with the significant investment required to initiate two Phase 3 clinical trials for GB-102 that were planned for late 2021 and, in August 2022, terminated all activities relating to GB-102 and GB-401, and reduced its workforce by 71%. As of December 31, 2022, the Company is continuing the preclinical development of two remaining programs and has eight remaining employees. As a result, anticipated operating expenses have been significantly reduced and management continues to believe that, if the Merger fails to close, the Company’s current cash, cash equivalents and short-term investments would be adequate to meet its cash needs for at least 12 months from the issuance date of this Annual Report on Form 10-K.

If the Merger fails to close, the Company may pursue financing alternatives, similar to what it has previously executed, which include debt and equity financing. There are no assurances that this process would result in any such transaction and such sources of capital may not be available to the Company in the necessary time frame, in the amounts that the Company requires, on terms that are acceptable to the Company, or at all. If the Merger fails to close, the Company may be unable to consummate a future acquisition, company sale, merger, divestiture of assets or other strategic transaction or raise the necessary funds when needed or reduce spending on required activities, it may not be able to continue the preclinical development of its remaining products, or it could be required to delay, scale back, or eliminate some or all of its research and development programs and other operations, including personnel, any of which may materially harm its business, financial position and results of operations.

COVID-19 Pandemic

The impact of the worldwide spread of a novel strain of coronavirus (“COVID-19”) has been unprecedented and unpredictable, including the emergence of new variants of the coronavirus, such as the Delta and Omicron variants, and resurgences in number and rates of infections, but based on the Company’s current assessment, the Company does not expect any material impact on its long-term strategic plans, operations, or its liquidity due to the worldwide spread of COVID-19. However, the Company is continuing to assess the effect on its operations by monitoring the spread of COVID-19 and the actions implemented to combat the virus and new variants thereof throughout the world and its assessment of the impact of COVID-19 may change.

Organization - Additional Information (Details) $ in Thousands		2 Months Ended	12 Months Ended
	Aug. 18, 2022	Oct. 31, 2022 Employee	Dec. 31, 2022 USD ($) Employees Program	Dec. 31, 2021 USD ($)
Subsidiary or Equity Method Investee [Line Items]
Workforce reduction percentage	71.00%
Restructuring charge			$ 3,000
Number of employees terminated \| Employee		20
Accumulated deficit			$ 204,793	$ 169,188
Number of remaining programs \| Program			2
Number of remaining employees \| Employees			8

Income Taxes - Schedule of Reconciliation of Federal Statutory Income Tax Rate to Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Abstract]
Federal statutory income tax rate	21.00%	21.00%
State income taxes, net of federal benefit	(2.50%)	0.60%
Research and development tax credits	1.70%	1.40%
Other	(5.30%)	(0.40%)
Change in valuation allowance	(14.90%)	(22.60%)

Fair Value Measurements - Summary of Company 's Financial Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Aggregate Fair Value	$ 12,374	$ 13,149
Total short-term investments, Aggregate Fair Value	21,824	50,306
Total asset measured at fair value, Aggregate Fair Value	34,198	63,455
Fair Value, Recurring
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost	12,374	13,149
Total cash equivalents, Aggregate Fair Value	12,374	13,149
Total short-term investments, Amortized Cost	21,861	50,322
Total short-term investments, Unrealized Gains	2	6
Total short-term investments, Unrealized Losses	(39)	(22)
Total short-term investments, Aggregate Fair Value	21,824	50,306
Total asset measured at fair value, Amortized Cost	34,235	63,471
Total asset measured at fair value, Unrealized Gains	2	6
Total asset measured at fair value, Unrealized Losses	(39)	(22)
Total asset measured at fair value, Aggregate Fair Value	34,198	63,455
Fair Value, Recurring \| Money Market Funds
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost	12,374	8,920
Total cash equivalents, Aggregate Fair Value	12,374	8,920
Fair Value, Recurring \| Corporate Debt Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost		1,480
Total cash equivalents, Aggregate Fair Value		1,480
Total short-term investments, Amortized Cost	1,001	1,117
Total short-term investments, Unrealized Losses	(1)	(1)
Total short-term investments, Aggregate Fair Value	1,000	1,116
Fair Value, Recurring \| Commercial Paper
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents, Amortized Cost		2,749
Total cash equivalents, Aggregate Fair Value		2,749
Total short-term investments, Amortized Cost	17,405	41,956
Total short-term investments, Unrealized Gains	2	6
Total short-term investments, Unrealized Losses	(29)	(8)
Total short-term investments, Aggregate Fair Value	17,378	41,954
Fair Value, Recurring \| U.S. Treasury Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total short-term investments, Amortized Cost	1,499	7,249
Total short-term investments, Unrealized Losses	(9)	(13)
Total short-term investments, Aggregate Fair Value	1,490	$ 7,236
Fair Value, Recurring \| U.S. Government Sponsored Entities - Mortgage Backed Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total short-term investments, Amortized Cost	1,956
Total short-term investments, Aggregate Fair Value	$ 1,956

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Basis of Presentation and Principles of Consolidation

Use of Estimates

Cash and Cash Equivalents

Investments

Concentrations of Credit Risk and Off-balance Sheet Risk

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

Leases

Restructuring, Impairment and Other Costs of Terminated Programs

Refer to Note 6 for additional information on the severance expense that the Company recognized for employees terminated in connection with the August 2022 reduction-in-force.

Long-lived Asset Impairment

Research and Development Expenses

Accrued Research and Development Costs

Patents Costs

Patent Costs

Stock-based Compensation

Recently Adopted and Recently Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 17,304	$ 13,364
Short-term investments	21,824	50,306
Prepaid expenses and other current assets	542	3,408
Total current assets	39,670	67,078
Property and equipment, net		1,981
Prepaid expenses and other non-current assets		29
Total assets	39,670	69,088
Current liabilities:
Accounts payable	1,716	527
Accrued research and development	200	304
Operating lease liability, current	203
Other current liabilities	1,580	3,226
Total current liabilities	3,699	4,057
Deferred rent, long term portion		8
Total liabilities	3,699	4,065
Commitments and contingencies (Note 5)
Stockholders’ Equity:
Common stock, $0.0001 par value; 500,000,000 shares authorized, 21,696,433 and 21,357,773 shares issued and outstanding as of December 31, 2022 and 2021,respectively	2	2
Additional paid-in capital	240,799	234,225
Accumulated deficit	(204,793)	(169,188)
Accumulated other comprehensive loss	(37)	(16)
Total stockholders’ equity	35,971	65,023
Total liabilities and stockholders’ equity	$ 39,670	$ 69,088

Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash equivalents	$ 12,374	$ 13,149
Short-term investments	21,824	50,306
Assets measured at fair value	34,198	63,455
Money Market Funds
Current assets:
Cash equivalents	12,374	8,920
Corporate Debt Securities
Current assets:
Cash equivalents		1,480
Short-term investments	1,000	1,117
Commercial Paper
Current assets:
Cash equivalents		2,749
Short-term investments	17,378	41,954
U.S. Treasury Notes
Current assets:
Short-term investments	1,490	7,235
U.S. Government Sponsored Entities - Mortgage Backed Securities
Current assets:
Short-term investments	1,956
Level 1
Current assets:
Cash equivalents	12,374	8,920
Assets measured at fair value	12,374	8,920
Level 1 \| Money Market Funds
Current assets:
Cash equivalents	12,374	8,920
Level 2
Current assets:
Cash equivalents		4,229
Short-term investments	21,824	50,306
Assets measured at fair value	21,824	54,535
Level 2 \| Corporate Debt Securities
Current assets:
Cash equivalents		1,480
Short-term investments	1,000	1,117
Level 2 \| Commercial Paper
Current assets:
Cash equivalents		2,749
Short-term investments	17,378	41,954
Level 2 \| U.S. Treasury Notes
Current assets:
Short-term investments	1,490	$ 7,235
Level 2 \| U.S. Government Sponsored Entities - Mortgage Backed Securities
Current assets:
Short-term investments	$ 1,956

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 6,713	$ 5,375
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	1,360	1,210
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 5,353	$ 4,165

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

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,
	2022		2021
Manufacturing and laboratory equipment	$	—	$	2,511
Computer hardware		—		28
Office furniture and equipment		—		28
Leasehold improvements		—		234
Construction in progress		—		833
Total property and equipment, at cost		—		3,634
Less: accumulated depreciation		—		(1,653	)
Property and equipment, net	$	—	$	1,981

Restructuring, Impairment and Other Costs of Terminated Programs - Schedule of Severance and Termination Benefits Over the Service Period (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Restructuring Cost and Reserve [Line Items]
Expense recognized during the period	$ 3,000
Severance and Termination Benefit
Restructuring Cost and Reserve [Line Items]
Total severance and other termination benefits, at fair value	1,065
Expense recognized during the period	1,065
Payments during the period	(941)
Liability balance as of December 31, 2022	$ 124

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2022

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss Per Common Share

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


	Year Ended December 31,
	2022			2021
Net loss	$	(35,605	)	$	(35,821	)
Net loss per share—basic and diluted	$	(1.66	)	$	(1.69	)
Weighted-average number of shares used in computing net loss per share—basic and diluted		21,489,280			21,199,291

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

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


	As of December 31,
	2022		2021
Stock options to purchase common stock		4,352,440		3,777,398
Restricted stock units		3,315,616		969,700
Warrants to purchase common stock		27,759		27,759

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating expenses:
Research and development	$ 14,113	$ 18,903
General and administrative	19,104	17,044
Restructuring, impairment and other costs of terminated programs	2,963
Total operating expenses	36,180	35,947
Loss from operations	(36,180)	(35,947)
Interest income	575	126
Net loss	$ (35,605)	$ (35,821)
Net loss per share-basic	$ (1.66)	$ (1.69)
Net loss per share-diluted	$ (1.66)	$ (1.69)
Weighted-average number of shares outstanding used in computing net loss per share-basic	21,489,280	21,199,291
Weighted-average number of shares outstanding used in computing net loss per share-diluted	21,489,280	21,199,291

Income Taxes - Schedule of Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets
Federal and state net operating loss carryforwards	$ 38,253	$ 34,431
Research and development tax credits	5,071	5,408
Capitalized research and development expense	2,323
Other	882	1,408
Gross deferred tax assets	46,529	41,247
Less: valuation allowance	$ (46,529)	(41,215)
Total deferred tax assets		32
Deferred tax liabilities
Depreciation		(32)
Total deferred tax liabilities		$ (32)

Restructuring, Impairment and Other Costs of Terminated Programs - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Restructuring Cost and Reserve [Line Items]
Impairment of right-of-use asset	$ 290
Severance and Termination Benefit
Restructuring Cost and Reserve [Line Items]
Severance payments not paid	$ 124

Income Taxes - Schedule of Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Abstract]
Balance—beginning of year	$ 2,090	$ 1,981
Addition based on tax position related to current year	155	257
(Reduction) addition based on tax position related to prior year	(275)	(148)
Balance—end of year	$ 1,970	$ 2,090