0001564590-21-013027 | 10-K | XBRL Viewer

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2020	Mar. 10, 2021	Jun. 30, 2020
Cover [Abstract]
Entity Registrant Name	Clearside Biomedical, Inc.
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	CLSD
Document Type	10-K
Entity Central Index Key	0001539029
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		57,422,475
Entity Public Float			$ 66,100,000
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-37783
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-2437375
Entity Address, Address Line One	900 North Point Parkway
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	Alpharetta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30005
City Area Code	678
Local Phone Number	270-3631
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	Portions of the Company’s definitive proxy statement, to be filed pursuant to Regulation 14A under the Securities Exchange Act of 1934, for its 2021 Annual Meeting of Stockholders are incorporated by reference in Part III of the Form 10-K.

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 17,287	$ 22,595
Prepaid expenses	722	1,139
Other current assets	109	1,485
Total current assets	18,118	25,219
Property and equipment, net	416	541
Operating lease right-of-use asset	528	656
Restricted cash	260	360
Total assets	19,322	26,776
Current liabilities:
Accounts payable	1,997	1,280
Accrued liabilities	1,582	2,930
Current portion of long-term debt	991	1,333
Current portion of operating lease liabilities	373	360
Deferred revenue	5,000	5,000
Total current liabilities	9,943	10,903
Long-term debt		3,819
Operating lease liabilities	616	897
Total liabilities	10,559	15,619
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized and no shares issued at December 31, 2020 and 2019
Common stock, $0.001 par value; 100,000,000 shares authorized at December 31, 2020 and 2019; 51,860,941 and 44,413,372 shares issued and outstanding at December 31, 2020 and 2019, respectively	52	44
Additional paid-in capital	264,578	248,770
Accumulated deficit	(255,867)	(237,657)
Total stockholders’ equity	8,763	11,157
Total liabilities and stockholders’ equity	$ 19,322	$ 26,776

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares, issued	51,860,941	44,413,372
Common stock, shares outstanding	51,860,941	44,413,372

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
Statements of Operations - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
License and other revenue	$ 7,894	$ 2,173	$ 30
Type of Revenue [Extensible List]	clsd:LicenseAndOtherRevenueMember	clsd:LicenseAndOtherRevenueMember	clsd:LicenseAndOtherRevenueMember
Operating expenses:
Research and development	$ 15,073	$ 15,658	$ 68,291
General and administrative	10,756	16,819	14,684
Total operating expenses	25,829	32,477	82,975
Loss from operations	(17,935)	(30,304)	(82,945)
Other (expense) income	(275)	(466)	127
Net loss	$ (18,210)	$ (30,770)	$ (82,818)
Net loss per share of common stock — basic and diluted	$ (0.39)	$ (0.81)	$ (2.69)
Weighted average shares outstanding — basic and diluted	46,506,540	38,170,830	30,733,600

Statement of Stockholders' Equity (Deflicit) - USD ($) $ in Thousands	Total	Cumulative effect of accounting change	Common Stock	Additional Paid-In-Capital	Accumulated Deficit	Accumulated Deficit Cumulative effect of accounting change	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Cumulative effect of accounting change
Beginning balance at Dec. 31, 2017	$ 21,415		$ 25	$ 145,618	$ (124,220)		$ (8)
Beginning balance, shares at Dec. 31, 2017			25,354,651
Issuance of common shares under follow-on offering	79,564		$ 7	79,557
Issuance of common stock in follow-on offering, shares			6,548,712
Issuance of common shares under employee stock purchase plan	50			50
Issuance of common shares under employee stock purchase plan, shares			12,595
Exercise of stock options	465			465
Exercise of stock options, shares			203,269
Share-based compensation expense	4,785			4,785
Net loss	(82,818)				(82,818)
Ending balance at Dec. 31, 2018	23,620	$ 159	$ 32	230,475	(206,887)	$ 151		$ 8
Ending balance, shares at Dec. 31, 2018			32,119,227
Issuance of common shares from at-the-market sales agreement	10,319		$ 9	10,310
Issuance of common shares from at-the-market sales agreement, shares			8,976,940
Issuance of common shares in private placement	3,324		$ 3	3,321
Issuance of common shares from private placement, shares			3,178,367
Issuance of common shares under employee stock purchase plan	45			45
Issuance of common shares under employee stock purchase plan, shares			52,476
Exercise of stock options	7			7
Exercise of stock options, shares			16,362
Vesting and settlement of restricted stock units, shares			70,000
Share-based compensation expense	4,612			4,612
Net loss	(30,770)				(30,770)
Ending balance at Dec. 31, 2019	11,157		$ 44	248,770	(237,657)
Ending balance, shares at Dec. 31, 2019			44,413,372
Issuance of common shares from at-the-market sales agreement	11,958		$ 6	11,952
Issuance of common shares from at-the-market sales agreement, shares			6,176,415
Issuance of common shares under employee stock purchase plan	31			31
Issuance of common shares under employee stock purchase plan, shares			35,359
Exercise of stock options	227		$ 2	225
Exercise of stock options, shares			254,466
Vesting and settlement of restricted stock units, shares			981,329
Share-based compensation expense	3,600			3,600
Net loss	(18,210)				(18,210)
Ending balance at Dec. 31, 2020	$ 8,763		$ 52	$ 264,578	$ (255,867)
Ending balance, shares at Dec. 31, 2020			51,860,941

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net loss	$ (18,210)	$ (30,770)	$ (82,818)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	180	211	189
Share-based compensation expense	3,600	4,612	4,785
Non-cash interest expense	59	163	154
Accretion of debt discount	129	67	112
Loss on disposal of fixed assets		63
Amortization and accretion on available-for-sale investments, net		(115)	(748)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,893	(558)	(505)
Other assets and liabilities	(140)	(159)	(55)
Accounts payable and accrued liabilities	(631)	(5,582)	(314)
Deferred revenue		5,000
Net cash used in operating activities	(13,120)	(27,068)	(79,200)
Investing activities
Maturities of available-for-sale-investments		32,950	76,470
Purchase of available-for-sale investments			(80,142)
Acquisition of property and equipment	(55)	(25)	(88)
Net cash (used in) provided by investing activities	(55)	32,925	(3,760)
Financing activities
Proceeds from at-the-market sales agreement, net of issuance costs	11,958	10,319
Proceeds from private placement, net of issuance costs		3,324
Proceeds from follow-on offering, net of issuance costs			79,564
Proceeds from exercise of stock options	227	7	465
Proceeds from shares issued under employee stock purchase plan	31	45	50
Proceeds from issuance of long-term debt	991		10,000
Principal payments made on long-term debt	(5,340)	(5,000)	(8,300)
Net cash provided by financing activities	7,867	8,695	81,779
Net (decrease) increase in cash, cash equivalents and restricted cash	(5,308)	14,552	(1,181)
Cash, cash equivalents and restricted cash, beginning of period	22,955	8,403	9,584
Cash, cash equivalents and restricted cash, end of period	17,647	22,955	8,403
Supplemental disclosure
Interest paid	524	843	751
Reconciliation of cash, cash equivalents and restricted cash;
Cash and cash equivalents	17,287	22,595	8,043
Restricted cash	360	360	360
Cash, cash equivalents and restricted cash, end of period	$ 17,647	$ 22,955	$ 8,403

The Company

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

The Company

1. The Company

Clearside Biomedical, Inc. (the “Company”) is a biopharmaceutical company dedicated to developing and delivering treatments that restore and preserve vision for people with serious back of the eye diseases. The Company’s proprietary SCS Microinjector targeting the suprachoroidal space offers unique access to the macula, retina and choroid where sight-threatening disease often occurs. This suprachoroidal space injection platform is an inherently flexible, in-office, non-surgical procedure, intended to provide targeted delivery to the site of disease and to work with both established and new formulations of medications, as well as future therapeutic innovations such as gene therapy. Incorporated in the State of Delaware on May 26, 2011, the Company has its corporate headquarters in Alpharetta, Georgia.

The Company’s activities since inception have primarily consisted of developing product and technology rights, raising capital and performing research and development activities. The Company has no current source of revenue to sustain present activities, and does not expect to generate meaningful revenue until and unless the Company receives regulatory approval of and successfully commercializes its product candidates, either on its own or with a third party. The Company is subject to a number of risks and uncertainties similar to those of other life science companies at a similar stage of development, including, among others, the need to obtain adequate additional financing, successful development efforts including regulatory approval of products, compliance with government regulations, successful commercialization of potential products, protection of proprietary technology and dependence on key individuals.

Liquidity

The Company had cash and cash equivalents of $17.3 million as of December 31, 2020. On January 6, 2021, the Company entered into a securities purchase agreement with certain institutional purchasers that purchased 4.2 million shares of its common stock in a registered direct offering at a price of $2.851 per share. The Company raised net proceeds of $11.1 million after deducting offering expenses. In addition, subsequent to December 31, 2020, the Company sold 1.2 million shares of its common stock for net proceeds of $3.3 million under its at-the-market agreement with Cowen and Company, LLC.

The Company has funded its operations primarily through the sale of convertible preferred stock and common stock and the issuance of long-term debt. The Company will continue to need to obtain additional financing to fund future operations, including completing the development, partnering and potential commercialization of its primary product candidates. The Company will need to obtain financing to conduct additional trials for the regulatory approval of its product candidates if requested by regulatory bodies, and completing the development of any product candidates that might be acquired. If such products were to receive regulatory approval, the Company would need to obtain additional financing to prepare for the potential commercialization of its product candidates, if the Company decides to commercialize the products on its own.

The Company has suffered recurring losses and negative cash flows from operations since inception and anticipates incurring additional losses until such time, if ever, that it can obtain FDA approval to sell, and then generate significant revenue from commercializing its lead product candidate, XIPERE (triamcinolone acetonide suprachoroidal injectable suspension formulated for administration to the back of the eye), with its licensees. In the absence of product or other revenues, the amount, timing, nature or source of which cannot be predicted, the Company’s losses will continue as it conducts its research and development activities.

These conditions raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the financial statements are issued. Based on its current plans and forecasted expenses, the Company expect that its cash and cash equivalents as of the filing date, March 15, 2021, will enable it to fund its planned operating expenses and capital expenditure requirements into the first quarter of 2022. This estimate does not give effect to additional development milestone payments the Company might receive under the agreements with Bausch, REGENXBIO or Arctic Vision or in connection with any other potential license or collaboration agreement for XIPERE or any future product candidates. The Company has based this estimate on assumptions that may prove to be wrong, and it could exhaust its capital resources sooner than expected.

The Company’s financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result should the Company be unable to continue as a going concern.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Significant Accounting Policies

2. Significant Accounting Policies

Basis of Presentation

The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of income and expenses during the reporting periods. Significant items subject to such estimates and assumptions include revenue recognition, the accounting for useful lives to calculate depreciation and amortization, clinical trial expense accruals, share-based compensation expense and income tax valuation allowance. Actual results could differ from these estimates.

Effects of COVID-19

The COVID-19 pandemic is expected to continue to result in a global slowdown of economic activity. Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgment. As of the date of issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require it to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. These estimates may change as new events occur and additional information is obtained and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the financial statements.

Revenue Recognition

The Company recognizes revenue from its contracts with customers under Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“ASC Topic 606”). The Company’s primary revenue arrangements are license agreements which typically include upfront payments, regulatory and commercial milestone payments and royalties based on future product sales. The arrangements may also include payments for the Company’s SCS Microinjector devices as well as payments for assistance and oversight of the customer’s use of the Company’s technology. In determining the amount of revenue to be recognized under these agreements, the Company performs the following steps: (i) identifies the promised goods and services to be transferred in the contract, (ii) identifies the performance obligations, (iii) determines the transaction price, (iv) allocates the transaction price to the performance obligations and (v) recognizes revenue as the performance obligations are satisfied.

The Company receives payments from its customers based on billing schedules established in each contract. Up-front and other payments may require deferral of revenue recognition to a future period until the Company performs its obligations under the arrangement. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment.

Property and Equipment, Net

Property and equipment is recorded at historical cost. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets, or for leasehold improvement the lesser of the useful life or remaining lease term. Repairs and maintenance are expensed when incurred. Upon retirement or sale, the cost of the assets disposed of and the related accumulated depreciation are removed from the accounts, and any resulting gain or loss is included in the determination of net income.

Debt Discount

All debt discounts are recorded against the related debt obligation and are amortized using the effective interest rate method over the term of the underlying debt obligation and reflected in interest expense.

Income Taxes

Deferred tax assets or liabilities are recorded for temporary differences between financial statement and tax basis of assets and liabilities, using enacted rates in effect for the year in which the differences are expected to reverse. A valuation allowance is recorded if it is more likely than not that a deferred tax asset will not be realized. The Company has provided a full valuation allowance on its deferred tax assets, which primarily consist of cumulative net operating losses for the period from May 26, 2011 (inception) to December 31, 2020. Due to its history of operating losses since inception and losses expected to be incurred in the foreseeable future, a full valuation allowance was considered necessary.

Liabilities for uncertain tax positions are recognized based on a two-step process. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. Once it is determined that the position meets the recognition threshold, the second step requires estimating and measuring the largest amount of tax benefit that is more likely than not to be realized upon ultimate settlement. The difference between the amount of recognizable tax benefit and the total amount of tax benefit from positions filed or to be filed with the tax authorities is recorded as a liability for uncertain tax benefits.

Research and Development Costs

Research and development costs are charged to expense as incurred and include:

•

employee-related expenses, including salaries, benefits, travel and share-based compensation expense for research and development personnel;

•

expenses incurred under agreements with contract research organizations, contract manufacturing organizations and consultants that conduct preclinical studies and clinical trials;

•

costs associated with preclinical and clinical development activities;

•

costs associated with submitting regulatory approval applications for the Company’s product candidates;

•

costs associated with training physicians on the suprachoroidal injection procedure and educating and providing them with appropriate product candidate information;

•

costs associated with technology and intellectual property licenses;

•

costs for the Company’s research and development facility; and

•

depreciation expense for assets used in research and development activities.

Costs for certain development activities, such as clinical studies, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the patterns of costs incurred, and are reflected in the financial statements as prepaid or accrued expenses.

Share-Based Compensation

Compensation cost related to share-based awards granted to employees is measured based on the estimated fair value of the award at the grant date. The Company estimates the fair value of stock options using a Black-Scholes option pricing model. Compensation expense for options granted to non-employees is determined as the fair value of consideration received or the fair value of the equity instruments issued, whichever is more reliably measured. The fair value of restricted stock units granted is measured based on the market value of the Company’s common stock on the date of grant. Share-based compensation costs are expensed on a straight-line basis over the relevant vesting period.

Compensation cost related to shares purchased through the Company’s employee stock purchase plan, which is considered compensatory, is based on the estimated fair value of the shares on the offering date, including consideration of the discount and the look back period. The Company estimates the fair value of the shares using a Black-Scholes option pricing model. Compensation expense is recognized over the six-month withholding period prior to the purchase date.

All share-based compensation costs are recorded in general and administrative or research and development costs in the statements of operations based upon the underlying employees’ roles within the Company.

Cash Equivalents

Cash equivalents consist of short-term, highly liquid investments with an original term of three months or less at the date of purchase.

Restricted Cash

The Company is required to maintain a stand-by letter of credit as a security deposit for its facility lease in Alpharetta, Georgia. The Company’s bank requires the Company to maintain a restricted cash balance to serve as collateral for the letter of credit issued to the landlord by the bank. As of December 31, 2020, the restricted cash balance was invested in a commercial money market account. The current portion of the restricted cash is recorded in other current assets and the long-term portion is recorded in restricted cash.

Concentration of Credit Risk Arising From Cash Deposits in Excess of Insured Limits

The Company maintains its cash in bank deposits that at times may exceed federally insured limits. The Company has not experienced any loss in such accounts. The Company believes it is not exposed to any significant risks with respect to its cash balances.

Recent Accounting Pronouncements

Accounting Pronouncements Recently Adopted

In August 2018, the FASB issued Accounting Standards Update (“ASU”) 2018-13, Fair Value Measurement (Topic 820-10): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which changes the fair value measurement disclosure requirements of ASC Topic 820, Fair Value Measurements and Disclosures. Under this ASU, certain disclosure requirements for fair value measurements are eliminated, amended or added. These changes aim to improve the overall usefulness of disclosures to financial statement users and reduce unnecessary costs to companies when preparing the disclosures. The Company adopted ASU 2018-13 on January 1, 2020, and the adoption did not have a material impact on its financial statements and disclosures.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost, including trade receivables. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model that requires the use of forward-looking information to calculate credit loss estimates. The Company adopted ASU 2016-13 on January 1, 2020, and the adoption did not have a material impact on its financial statements and related disclosures.

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes by removing certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The new ASU also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates. These changes aim to improve the overall usefulness of disclosures to financial statement users and reduce unnecessary costs to companies when preparing the disclosures. The guidance is effective for the Company beginning on January 1, 2021 and prescribes different transition methods for the various provisions. The Company does not expect the adoption of ASU 2019-12 to have a material impact on its financial statements and related disclosures.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2020

Property Plant And Equipment [Abstract]

Property and Equipment, Net

3. Property and Equipment, Net

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

	Estimated Useful Lives (Years)	December 31,
		2020			2019
Furniture and fixtures	5	$	337		$	337
Machinery and equipment	5		176			121
Computer equipment	3		13			13
Leasehold improvements	Lesser of useful life or remaining lease term		667			667
Total property and equipment			1,193			1,138
Less: Accumulated depreciation			(777	)		(597	)
Property and equipment, net		$	416		$	541

Accrued Liabilities

12 Months Ended

Dec. 31, 2020

Payables And Accruals [Abstract]

Accrued Liabilities

4. Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Accrued research and development	$	234	$	359
Accrued employee costs		1,132		1,530
Accrued severance		—		751
Accrued professional fees		56		58
Accrued expense		160		232
	$	1,582	$	2,930

Long-Term Debt

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Long-Term Debt

5. Long-Term Debt

Loan and Security Agreements

On May 14, 2018, the Company entered into a second amended and restated loan and security agreement (the “2^nd A&R Loan Agreement”) with Silicon Valley Bank (“SVB”), MidCap Funding III Trust and MidCap Financial Trust (together, “MidCap” and collectively with SVB, the “Lenders”). The 2^nd A&R Loan Agreement provided for new term loans of up to $20.0 million, with a floating interest rate equal to 6.50% plus the greater of (i) the 30-day U.S. LIBOR, as reported in the Wall Street Journal on the last business day of the month the immediately precedes the month in which the interest will accrue, or (ii) 1.89%. The 2^nd A&R Loan Agreement included, among other things, the ability of the Lenders to accelerate the payment of the term loan in the event of a material adverse change and restrictions on the Company’s ability to sell, assign, license, transfer or otherwise dispose of its assets, including intellectual property assets, without the prior written consent of the Lenders.

The Company borrowed an initial tranche of $10.0 million on May 14, 2018, of which $7.0 million was used to repay all amounts outstanding under a prior loan agreement, including fees associated with the final payment. The prepayment fees were waived. Of the remaining $10.0 million available under the 2^nd A&R loan agreement, the Company elected not to draw $5.0 million and the other $5.0 million was not available for draw.

On October 18, 2019, the Company entered into an amendment to the 2^nd A&R Loan Agreement with the Lenders. Pursuant to the amendment, the Company repaid $5.0 million of the outstanding principal balance of the $10.0 million term loan. The Company did not pay any final payment or termination fees in connection with the $5.0 million prepayment. In addition, the Company and the Lenders agreed to modify the term loan repayment schedule. As amended, the term loan repayment schedule provided for interest only payments through October 31, 2020, followed by consecutive equal monthly payments of principal and interest in arrears continuing through the maturity date of October 1, 2022. The Company had the option to prepay the outstanding balance in full, subject to a prepayment fee. A final payment of 5.50% of the aggregate borrowed amount was due at maturity of the loan on October 1, 2022, or upon the prepayment of the facility or the acceleration of amounts due under the facility as a result of an event of default. The term loans under the 2^nd A&R loan agreement were secured by substantially all of the Company’s assets.

On May 7, 2020, due to various restrictions and other limiting covenants of the 2^nd A&R Loan Agreement, the Company prepaid in full the outstanding $5.0 million principal balance, plus $0.3 million reflecting the final payment fee and accrued interest. The prepayment fees were waived by the Lenders.

Interest expense on the borrowings under the loan agreements described above was $147,000, $804,000 and $791,000 for the years ended December 31, 2020, 2019 and 2018, respectively. Accretion of the scheduled final payment was $59,000, $163,000 and $154,000 for the years ended December 31, 2020, 2019 and 2018, respectively. Accretion of the deferred closing costs was $129,000, $67,000 and $112,000 for the years ended December 31, 2020, 2019 and 2018, respectively.

CARES Act Paycheck Protection Program Loan

12 Months Ended

Dec. 31, 2020

Extraordinary And Unusual Items [Abstract]

CARES Act Paycheck Protection Program Loan

6. CARES Act Paycheck Protection Program Loan

On April 20, 2020, the Company entered into a loan agreement with SVB (the “PPP Lender”) under the terms of which the PPP Lender made a loan to the Company in an aggregate principal amount of $1.0 million (the “PPP Loan”) pursuant to the Paycheck Protection Program (the “PPP”) under the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”). The PPP Loan was evidenced by a promissory note (the “Note”) containing the terms and conditions for repayment of the PPP Loan.

Under the terms of the Note and the PPP Loan, interest accrued on the outstanding principal amount at the rate of 1.0% per annum. The term of the Note was until April 2022, with the Company obligated to make equal monthly payments of principal and interest, beginning in November 2020 and continuing until the maturity date.

The CARES Act and the PPP provided a mechanism for forgiveness of up to the full amount borrowed. Under the PPP, the Company could apply for forgiveness for all or a portion of the PPP Loan based on a formula that takes into account a number of factors, including the amount of loan proceeds used by the Company during the 24-week period after the loan origination for certain purposes, including payroll costs, interest on certain mortgage obligations, rent payments on certain leases, and certain qualified utility payments, provided that at least 60% of the loan amount has been used for eligible payroll costs; the employer maintaining or rehiring employees and maintaining salaries at certain levels; and other factors. Subject to the other requirements and limitations on loan forgiveness, only loan proceeds spent on payroll and other eligible costs qualified for forgiveness.

As of December 31, 2020, the Company had recorded the $1.0 million principal balance of the PPP Loan in current portion of long-term debt on the balance sheet. On January 11, 2021, the Company was notified by the PPP Lender that the PPP Loan had been forgiven for the full amount borrowed under the PPP Loan as well as approximately $7,000 of accrued interest. In accordance with ASC 405-20, Extinguishment of Liabilities, the income from the forgiveness of the amount borrowed amount and the accrued interest will be recognized in the statement of operations as a gain on loan extinguishment in the next reporting period.

Preferred and Common Stock

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Preferred and Common Stock

7. Preferred and Common Stock

The Company’s amended and restated certificate of incorporation authorizes the Company to issue 10,000,000 shares of $0.001 par value of preferred stock. As of December 31, 2020 and 2019, there were 10,000,000 shares of preferred stock authorized, none of which were issued and outstanding.

The Company’s amended and restated certificate of incorporation authorizes the Company to issue 100,000,000 shares of $0.001 par value common stock. As of December 31, 2020 and 2019, there were 51,860,941 and 44,413,372 shares of common stock outstanding, respectively.

Common Stock Warrants

12 Months Ended

Dec. 31, 2020

Common Stock Warrants [Abstract]

Common Stock Warrants

8. Common Stock Warrants

In September 2016, in connection with a loan agreement, the Company issued warrants to the lenders to purchase up to 29,796 shares of common stock at a price per share of $10.74. The warrants are fully exercisable and expire in September 2026, or earlier upon the occurrence of specified mergers or acquisitions of the Company. The warrants were recorded in equity at the time of issuance and had a remaining life of 5.75 years as of December 31, 2020.

Share-Based Compensation

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Share-Based Compensation

9. Share-Based Compensation

Stock Options

In January 2016, the Company’s board of directors adopted and approved the Clearside Biomedical, Inc. 2016 Equity Incentive Plan (the “2016 Plan”) which became effective on June 1, 2016. The 2016 Plan provides for the grant of share-based awards to employees, directors and consultants of the Company. The 2016 Plan provides for the grant of incentive stock options to employees, and for the grant of nonqualified stock options, restricted stock awards, restricted stock unit awards, stock appreciation rights, performance stock awards and other forms of stock compensation to the Company’s employees, directors, and non-employee third parties. The number of shares of common stock reserved for issuance under the 2016 Plan will automatically increase on January 1 each year, through January 1, 2026, by 4% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors. At December 31, 2020, under the 2016 Plan, options to purchase 3,794,184 shares of the Company’s common stock were outstanding at a weighted average price of $4.09 per share and 1,068,601 shares remained available for future grant. As of January 1, 2021, the number of shares of common stock that may be issued under the 2016 Plan was automatically increased by 2,074,437 shares, representing 4% of the total number of shares of common stock outstanding on December 31, 2020, increasing the number of shares of common stock available for issuance under the 2016 Plan as of that date to 3,143,038 shares.

As a result of the adoption of the 2016 Plan, no further grants may be made under the Company’s 2011 Stock Incentive Plan (the “2011 Plan”). The 2011 Plan provided for the grant of share-based awards to employees, directors and consultants of the Company. At December 31, 2020, options to purchase 436,773 shares of the Company’s common stock were outstanding under the 2011 Plan at a weighted average exercise price of $2.53 per share.

The Company has granted stock option awards to employees, directors and consultants. The total share-based compensation expense recognized is reflected in the statements of operations as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018

Research and development	$	1,183	$	1,379	$	1,766
General and administrative		1,574		2,728		3,004
Total	$	2,757	$	4,107	$	4,770

Share-based compensation is accounted for in accordance with the provisions of ASC 718, Compensation-Stock Compensation. The estimated fair value of options granted is determined as of the date of grant using the Black-Scholes option pricing model. The resulting fair value is recognized ratably over the requisite service period, which is generally the vesting period of the awards.

The following table sets forth the weighted average assumptions utilized in the Black-Scholes option pricing model to calculate the fair value of the underlying common stock for the years ended December 31, 2020, 2019 and 2018.

	Year Ended December 31,
	2020			2019			2018

Expected term (years)		7.00			7.00			7.00
Expected stock price volatility		108.13	%		109.49	%		93.08	%
Risk-free interest rate		1.52	%		2.49	%		2.87	%
Expected dividend yield		0.00	%		0.00	%		0.00	%

Expected term (in years): The Company utilized the simplified method as prescribed by ASC 718, as the Company does not have sufficient historical exercise and post-vesting termination data to provide a reasonable basis upon which to estimate the expected term of stock options granted to employees.

Risk-free interest rate: The risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected time to a possible liquidity event.

Expected dividend yield: The Company has not paid and does not anticipate paying any dividends in the foreseeable future.

Expected stock price volatility: The Company calculates expected volatility based on the historical volatility of its common stock.

Forfeitures: The Company records forfeitures as they occur.

The following table summarizes the activity related to stock options during the year ended December 31, 2020:

				Weighted
	Number of			Average
	Shares			Exercise Price

Options outstanding at December 31, 2019		4,104,450		$	4.63
Granted		1,100,250			2.31
Exercised		(254,466	)		0.89
Cancelled/Forfeited		(702,041	)		6.49
Options outstanding at December 31, 2020		4,248,193			3.95

Options exercisable at December 31, 2019		2,452,764			5.44

Options exercisable at December 31, 2020		2,355,900			4.96

The following table provides additional information about the Company’s stock options that were outstanding and exercisable at December 31, 2020 (aggregate intrinsic values in thousands):

							Weighted								Weighted
			Weighted				Average				Weighted				Average
			Average		Aggregate		Remaining				Average		Aggregate		Remaining
Exercise	Options		Exercise		Intrinsic		Contractual		Options		Exercise		Intrinsic		Contractual
Price	Outstanding		Price		Value		Life (Years)		Exercisable		Price		Value		Life (Years)

$0.00 - $2.99		2,598,987						8.12		1,011,680					7.08
$3.00 - $6.99		998,120					6.59			725,221					6.25
$7.00 - $8.99		449,308					6.16			432,847					6.12
$9.00 - $20.84		201,778						6.76		186,152					6.71
		4,248,193	$	3.95	$	2,753	7.49			2,355,900	$	4.96	$	1,551	6.62

As of December 31, 2020, the Company had $3.4 million of unrecognized compensation expense related to unvested stock options, which is expected to be recognized over a weighted average period of 2.1 years. The weighted average fair values of all stock options granted for the years ended December 31, 2020, 2019 and 2018 was $1.97 per share, $1.09 per share and $5.98 per share, respectively. The intrinsic value is calculated as the difference between the fair market value and the exercise price per share of the stock options. The fair market value per share of common stock as of December 31, 2020 was $2.74, which was the closing sale price of the Company’s common stock on the Nasdaq Global Market on that date.

Restricted Stock Units

The Company has granted restricted stock units (“RSUs”) to employees under the 2016 Plan. The shares underlying the RSU

awards have vesting terms of two to four years from the date of grant, subject to the employees’ continuous service and

subject to accelerated vesting in specified circumstances. The fair value of the RSUs granted is measured based on the market value of the Company’s common stock on the date of grant and is recognized ratably over the requisite service period, which is generally the vesting period of the awards.

The total share-based compensation expense related to RSUs is reflected in the statements of operations as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018
Research and development	$	375	$	177	$	—
General and administrative		427		306		—
Total	$	802	$	483	$	—

The following table summarizes the activity related to RSUs during the year ended December 31, 2020:

				Weighted Average
	Number of			Grant Date
	Shares			Fair Value
Non-vested RSUs outstanding at December 31, 2019		1,269,300		$	0.87
Granted		486,000			2.39
Vested		(981,329	)		0.91
Forfeited		(6,700	)		0.91
Non-vested RSUs outstanding at December 31, 2020		767,271			1.78

As of December 31, 2020, the Company had $1.0 million of unrecognized compensation expense related to the RSUs, which amount is expected to be recognized over a weighted average period of 2.5 years.

Employee Stock Purchase Plan

In January 2016, the Company’s board of directors adopted and approved the Clearside Biomedical, Inc. 2016 Employee Stock Purchase Plan (the “2016 ESPP”) which became effective on June 1, 2016. The 2016 ESPP permits employees to purchase shares of the Company’s common stock through payroll deductions up to 15% of their earnings. The number of shares reserved for issuance under the 2016 ESPP will automatically increase on January 1 of each year, through January 1, 2026, by the lesser of (i) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, (ii) 454,545 shares of common stock or (iii) a lesser number of shares as may be determined by the Company’s board of directors. The Company’s board of directors elected not to increase the shares reserved for issuance on January 1, 2021. The number of shares of common stock available for issuance under the 2016 ESPP as of December 31, 2020 was 570,972 shares.

The 2016 ESPP is considered a compensatory plan and the fair value of the discount and the look-back period are estimated using the Black-Scholes option pricing model and expense is recognized over the six-month withholding period prior to the purchase date. During the years ended December 31, 2020, 2019 and 2018, the Company issued 35,359, 52,476 and 12,595 shares, respectively, of common stock purchased under the 2016 ESPP.

The share-based compensation expense recognized for the 2016 ESPP is reflected in the statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018
Research and development	$	19	$	11	$	5
General and administrative		22		9		10
Total	$	41	$	20	$	15

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

10. Income Taxes

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

	December 31,
	2020			2019			2018
Deferred tax asset (liability)
Net operating loss carryforwards	$	51,414		$	46,305		$	41,152
Non-deductible accrued expenses		263			422			245
Right-of-use asset		(132	)		(138	)		-
Lease liability		247			264			-
Deferred rent		—			—			148
Deferred revenue		1,247			—			—
Stock compensation expense		2,044			1,472			899
Depreciation differences		(82	)		(94	)		(125	)
Federal tax credits		8,015			7,249			6,481
State tax credits		381			623			757
Disallowed interest expense		7			99			—
Charitable contributions		—			4			6
Valuation allowance		(63,404	)		(56,206	)		(49,563	)
Net deferred tax asset	$	—		$	—		$	—

A reconciliation of the statutory tax rates and the effective tax rates is as follows:

	Year Ended December 31,
	2020			2019			2018
U.S. federal tax rate		21.00	%		21.00	%		21.00	%
State tax rate		14.28			—			(0.73	)
Permanent difference and other		1.42			(1.33	)		(0.33	)
Tax credit		2.89			2.06			3.96
Valuation allowance		(39.66	)		(21.73	)		(20.39	)
ASC 740-10		(0.26	)		—			(4	)
Impact of federal rate change		—			—			—
		0.33	%		0.00	%		0.00	%

Certain items of income and expense are not reported in tax returns and financial statements in the same year. The tax effect of such temporary differences is reported as deferred income taxes. The measurement of deferred tax assets is reduced, if necessary, by the amount of any tax benefit that, based on available evidence, is not expected to be realized. The Company establishes a valuation allowance for deferred tax assets for which realization is not likely. As of each reporting date, management considers new evidence, both positive and negative, that could affect its view of the future realization of deferred tax assets.

At December 31, 2020, the Company had a valuation allowance of $63.4 million recorded against the benefit of certain deferred tax assets. The valuation allowance was primarily related to federal and state net operating loss ("NOL") carryforwards that, in the judgment of management, are not more likely than not to be realized. In assessing the recoverability of the Company’s deferred tax assets, management considered, among other things, its deferred tax liabilities, its historical earnings and losses, projections of future income, and tax-planning strategies available to the Company in the relevant jurisdiction. The Company will release this valuation allowance when management determines that it is more likely than not that its deferred tax asset will be realized.

At December 31, 2020, the Company had income tax NOL carryforwards for federal and state purposes of $232.7 million and $40.7 million, respectively. The Company has recorded a deferred tax asset for both federal and state NOL carryforwards of $48.9 million and $2.5 million, respectively. If not utilized, the federal NOL carryforwards will begin to expire beginning in 2031, and the state NOL carryforwards will begin to expire at various dates beginning in 2027. Additionally, under the 2017 Tax Cuts and Jobs Act, federal net operating losses incurred in 2018 and beyond may be carried forward indefinitely. However, the deductibility of such federal net operating losses is limited beginning in 2021. Certain states have also adopted the indefinite carryforward period beginning with the 2018 tax year, but state conformity varies state by state.

Liabilities for uncertain tax positions are recognized based on a two-step process. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. Once it is determined that the position meets the recognition threshold, the second step requires the Company to estimate and measure the largest amount of tax benefit that is more likely than not to be realized upon ultimate settlement. The difference between the amount of recognizable tax benefit and the total amount of tax benefit from positions filed or to be filed with the tax authorities is recorded as a liability for uncertain tax benefits.

The following is a rollforward of the Company’s uncertain tax positions (in thousands):

	Year Ended December 31,
	2020		2019
Balance of uncertain tax positions at the beginning of the year	$	2,903	$	2,903
Gross increases - tax positions in prior period		4,665		—
Balance of uncertain tax positions at the end of the year	$	7,568	$	2,903

As of December 31, 2020 and 2019, there was $7.6 million and $2.9 million, respectively, of unrecognized tax benefit that if recognized would be in the form of a net operating loss carryforward, which is expected to require a full valuation allowance based on present circumstances. The Company accrued $4.6 million of unrecognized tax benefit and $48,000 of unrecognized tax expenses for the year 2020. The Company recognizes accrued interest related to unrecognized tax expenses and penalties as income tax expense. No significant amounts of interest or penalties have been recorded as of December 31, 2020

- Definition

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

+ References + Details

Commitment and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

11. Commitments and Contingencies

Lease Commitment Summary

The Company leases its facilities and some of its equipment under noncancelable operating lease arrangements that expire at various dates through 2023. In November 2016, the Company signed an office lease agreement to lease approximately 20,000 square feet of office space in Alpharetta, Georgia for its corporate headquarters. The lease agreement is for a six and one-half year term with a renewal option for one additional five-year term. Rental payments are $35,145 per month subject to an increase of 3% per year. Operating lease cost under this lease is recognized on a straight-line basis over the term of the lease. In addition, the lease agreement requires payment of the pro-rata share of the annual operating expenses associated with the premises. The Company relocated to this space in March 2017.

In August 2018, the Company signed an office lease agreement to lease approximately 3,500 square feet of office space in Berkeley, California for its commercial operations. The lease agreement was for a two-year term with a renewal option for an additional one-year term. The Company did not exercise the renewal option for the Berkeley lease and terminated the lease on December 15, 2019, with no further payments due. The termination of the lease did not have a material impact on the Company’s statements of operations. Operating lease cost under this lease was recognized on a straight-line basis over the term of the lease. The Company also paid a pro-rata share of the annual operating expenses associated with the premises.

The Company’s operating leases included on the balance sheet are as follows (in thousands):

	December 31, 2020
Operating lease right-of-use asset	$	528

Liabilities
Current portion of operating lease liabilities	$	373
Operating lease liabilities		616
Total operating lease liabilities	$	989

The Company recognizes a right-of-use asset for the right to use the underlying asset for the lease term, and a lease liability, which represents the present value of the Company’s obligation to make payments over the lease term. The renewal option is not included in the calculation of the right-of-use asset and the lease liabilities as the Company has not yet determined if the Alpharetta, Georgia lease will be renewed. The present value of the lease payments is calculated using an incremental borrowing rate as the Company’s leases do not provide an implicit interest rate. At December 31, 2020, the Company’s incremental borrowing rate was 11.0% and the remaining lease term was 2.75 years.

Minimum lease payments were as follows at December 31, 2020 (in thousands):

Year ending December 31,
2021	$	392
2022		407
2023		316
Total minimum lease payments		1,115
Less imputed interest		(126	)
Total operating lease liabilities	$	989

Operating lease cost was $247,000 and $393,000 for the years ended December 31, 2020 and 2019, respectively. Variable lease cost was $95,000 and $83,000 for the years ended December 31, 2020 and 2019, respectively. Short-term lease cost was $12,000 and $20,000 for the years ended December 31, 2020 and 2019, respectively.

Contract Service Providers

In the course of the Company’s normal business operations, it has agreements with contract service providers to assist in the performance of its research and development, clinical research and manufacturing. Substantially all of these contracts are on an as needed basis.

In May 2018, the Company entered into a manufacturing supply agreement (the “Supply Agreement”), with Gerresheimer Regensburg GmbH, a company incorporated under the laws of Germany (“Gerresheimer”). Gerresheimer will manufacture and supply the Company’s proprietary SCS Microinjector. The Company will provide Gerresheimer with a rolling forecast schedule of its projected purchase orders for at least the next four calendar quarters. The Supply Agreement contains an initial five-year term that will automatically renew for successive periods of three years, unless terminated by either party at least 12 months prior to the end of the applicable term.

License and Other Agreements

12 Months Ended

Dec. 31, 2020

License And Other Agreement [Abstract]

License and Other Agreements

12. License and Other Agreements

Bausch + Lomb

On October 22, 2019, the Company entered into a License Agreement with Bausch + Lomb, a division of Bausch Health Companies, Inc. (“Bausch”). Pursuant to the Bausch License Agreement, the Company has granted an exclusive license to Bausch to develop, manufacture, distribute, promote, market and commercialize XIPERE using the Company’s proprietary microinjector (the “Device”), as well as specified other steroids, corticosteroids and NSAIDs in combination with the Device (“Other Products,” and together with XIPERE, the “Products”), subject to specified exceptions, in the United States and Canada (the “Original Territory”) for the treatment of ophthalmology indications, including non-infectious uveitis.

On April 27, 2020, the Company and Bausch entered into an amendment to the Company’s License Agreement with Bausch dated October 22, 2019 (as amended, the “Bausch License Agreement”). Pursuant to the Bausch License Agreement, the Company has granted Bausch an exclusive option (the “Option”) to develop, manufacture, distribute, promote, market and commercialize XIPERE in one or more of the following regions: (i) the European Union, including the United Kingdom, (ii) Australia and New Zealand and (iii) South America and Mexico (such regions, the “Additional Regions” and together with the Original Territory, the “Territory”). The Option may be exercised any time before the earlier of regulatory approval of XIPERE in the United States and August 31, 2021.

Pursuant to the Bausch License Agreement, Bausch made an upfront payment of $5.0 million (the “Upfront Payment”) in October 2019, which is subject to a refund if the Bausch License Agreement is terminated in specified circumstances. In addition, Bausch has agreed to make additional payments of up to $15.0 million upon the achievement of specified pre-launch development and regulatory milestones (the “Pre-Launch Milestone Payments”) and up to an aggregate of $57.3 million in additional milestone payments upon the achievement of (i) specified regulatory approvals for specified additional indications of XIPERE (including certain regulatory and commercial milestones if Bausch exercises its Option in the European Union) and (ii) specified levels of annual net sales (as defined in the Bausch License Agreement). Further, during the applicable royalty term, the Company will also be entitled to receive tiered royalties at increasing percentages, from the high-teens to twenty percent, based on XIPERE achieving certain annual net sales thresholds in the Original Territory, as well as a lower royalty on annual net sales of Other Products in the Original Territory and on annual net sales of Xipere in the Additional Regions if Bausch exercises its Option, in each case subject to reductions in specified circumstances; provided that the Company will not receive any royalties on the first $45.0 million of cumulative net sales of all products in the Original Territory.

During the term of the Bausch License Agreement, and in the Territory, the Company has agreed not to (i) develop or commercialize XIPERE alone or in combination with an Other Device (as defined in the Bausch License Agreement) in the licensed field, (ii) develop or commercialize any corticosteroid with the Device or an Other Device in the licensed field, (iii) develop or commercialize the Device or an Other Device with any active pharmaceutical ingredient for non-infectious uveitis or macular edema associated with non-infectious uveitis, including with any Other Drug (as defined in the Bausch License Agreement, which are restricted to those steroids, corticosteroids and non-steroidal anti-inflammatory drugs specifically identified in the Bausch License Agreement), (iv) develop or commercialize any Other Drug in combination with the Device and (v) commercialize any Other Device for achieving non-surgical access to the suprachoroidal space where such device is sold as a stand-alone product, subject to specified exceptions. The Bausch License Agreement will expire upon expiration of the royalty terms for all Products and countries in the Territory, with each royalty term for a given Product and country ending on the latest of (i) the date of expiration of the last-to-expire valid claim of any licensed patent rights covering such Product in such country in the Territory, (ii) the date of the loss of regulatory exclusivity for such Product in such country in the Territory, or (iii) ten years from the later of the first sale of such Product in such country in the Territory. For a specified period of time, Bausch may terminate the Bausch License Agreement immediately and have the Upfront Payment refunded if the U.S. Food and Drug Administration (the “FDA”) has not approved the Company’s New Drug Application (“NDA”) for XIPERE by August 31, 2021. Following the payment of the Pre-Launch Milestone Payments, Bausch may also terminate the Bausch License Agreement for convenience upon 180 days’ written notice. In addition, the Company can terminate the Bausch License Agreement if Bausch commences a legal action challenging the validity, enforceability or scope of any of the licensed patents. If the FDA requires an additional clinical trial prior to approving the NDA for XIPERE and the Company notifies Bausch that the Company will not conduct the trial at the Company’s expense, then Bausch may terminate the Bausch License Agreement and have the Upfront Payment refunded within 60 days of the receipt of such notice from the Company. Both parties may terminate the Bausch License Agreement (i) upon a material breach of the Bausch License Agreement, subject to a specified cure period and specified exceptions, or (ii) if the other party encounters bankruptcy or insolvency. Upon termination (other than for a material breach by or bankruptcy or insolvency event of the Company), all licenses and other rights granted by the Company to Bausch pursuant to the Bausch License Agreement would revert to the Company.

The Company is responsible for all development expenses for XIPERE in the Original Territory until the NDA is approved by the FDA, subject to specified exceptions, as well as manufacturing costs in connection with the NDA. The Company is also responsible for all clinical and development expenses conducted to satisfy the FDA’s requests in the complete response letter issued on October 18, 2019 related to the NDA and any subsequent complete response letter related to the NDA (the “CRL-related expenses”). If XIPERE is approved by the FDA, Bausch will be responsible for all expenses following such approval; provided that the Company will be responsible for the CRL-related expenses and for one-half of the costs of any post-approval clinical trials required by the FDA, up to a specified maximum amount.

Due to the refund provisions in the License Agreement, the upfront payment of $5.0 million received from Bausch was included on the balance sheet as deferred revenue as of December 31, 2020 and 2019 and will remain in deferred revenue until the refund provisions lapse.

REGENXBIO, Inc.

On August 29, 2019, the Company entered into an option and license agreement with REGENXBIO, Inc. (“REGENXBIO”) pursuant to which the Company granted REGENXBIO an exclusive option to enter into a commercial license agreement (the “Option”), which grants REGENXBIO an exclusive, worldwide and sublicensable license to the Company’s SCS Microinjector for the delivery of adeno-associated virus-based gene therapies for the treatment of wet age-related macular degeneration, diabetic retinopathy and other conditions for which anti-vascular endothelial growth factor treatment is currently the standard of care. REGENXBIO exercised the Option in October 2019 and paid the Company an option fee equal to $2.0 million, less a credit of $0.5 million previously received under a technology access agreement. In addition, REGENXBIO has agreed to pay the Company up to an aggregate of $34.0 million in milestone payments upon the achievement of specified development milestones and up to an aggregate of $102.0 million in sales-based milestone payments, as well as mid-single digit royalties on net sales of products using the SCS Microinjector during the royalty term. In September 2020, the Company received $3.0 million in milestone payments under the Option.

Arctic Vision (Hong Kong) Limited

On March 10, 2020, the Company entered into a License Agreement (the “License Agreement”) with Arctic Vision (Hong Kong) Limited (“Arctic Vision”). Pursuant to the License Agreement, the Company has granted an exclusive license to Arctic Vision to develop, distribute, promote, market and commercialize XIPERE, subject to specified exceptions, in China, Hong Kong, Macau, Taiwan and South Korea (the “Territory”). Under the terms of the License Agreement, neither party may commercialize XIPERE in the other party’s territory. Arctic Vision has agreed to use commercially reasonably efforts to pursue development and commercialization of XIPERE for indications associated with uveitis in China, Hong Kong, Macau, Taiwan and South Korea (the “Arctic Territory”). In addition, upon receipt of the Company’s consent, Arctic Vision will have the right, but not the obligation, to develop and commercialize XIPERE for additional indications in the Arctic Territory.

Pursuant to the License Agreement, Arctic Vision has agreed to pay the Company up to a total of $35.5 million. This amount includes an upfront payment of $4.0 million as well as an aggregate of up to $31.5 million in development milestone payments for specified events prior to and including receipt of approval of XIPERE in the United States and sales milestone payments for achievement of specified levels of net sales. Further, during the applicable royalty term, the Company will also be entitled to receive tiered royalties of ten to twelve percent of net sales based on achieving certain annual net sales thresholds in the Territory, subject to customary reductions, payable on a product-by-product and country-by-country basis, commencing at launch in such country and lasting until the latest of (i) the date that all valid claims within the licensed patent rights covering XIPERE have expired, (ii) the date of the loss of marketing or regulatory exclusivity of XIPERE in a given country, or (iii) ten years from the first commercial sale of XIPERE in a given country. In March 2020, the Company received an upfront payment of $4.0 million under the License Agreement.

Other

The Company periodically enters into short-term agreements with other customers to evaluate the potential use of its proprietary SCS Microinjector with third-party product candidates for the treatment of various diseases. Funds received from these agreements are recognized as revenue over the term of the agreement. The Company recorded $200,000, $105,000 and $30,000 of revenue from these agreements during the years ended December 31, 2020, 2019 and 2018, respectively.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

13. Fair Value Measurements

The Company’s material financial instruments at December 31, 2020 and 2019 consisted primarily of cash and cash equivalents and long-term debt. The fair value of cash and cash equivalents, other current assets and accounts payable approximate their respective carrying values due to the short-term nature of these instruments and are classified as Level 1 in the fair value hierarchy. The fair value of long-term debt approximates the carrying value due to variable interest rates that correspond to market rates.

There were no significant transfers between Levels 1, 2 and 3 during the years ended December 31, 2020 and 2019.

The following tables summarize the fair value of financial assets and liabilities that are measured at fair value and the classification by level of input within the fair value hierarchy (in thousands):

	December 31, 2020
	Level 1		Level 2		Level 3		Recorded Value
Financial Assets:
Cash and money markets	$	17,287	$	—	$	—	$	17,287
Restricted cash money market		360		—		—		360
Total financial assets	$	17,647	$	—	$	—	$	17,647

	December 31, 2019
	Level 1		Level 2		Level 3		Recorded Value
Financial Assets:
Cash and money markets	$	22,595	$	—	$	—	$	22,595
Restricted cash money market		360		—		—		360
Total financial assets	$	22,955	$	—	$	—	$	22,955

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Net Loss per Share

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Net Loss Per Share

14. Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period, without consideration of the dilutive effect of potential common stock equivalents. Diluted net loss per share gives effect to all dilutive potential shares of common stock outstanding during this period.

For all periods presented, the Company’s potential common stock equivalents, which included convertible preferred stock, stock options, unvested restricted stock and stock purchase warrants, have been excluded from the computation of diluted net loss per share as their inclusion would have the effect of reducing the net loss per share. Therefore, the denominator used to calculate both basic and diluted net loss per share is the same in all periods presented.

The Company’s potential common stock equivalents that have been excluded from the computation of diluted net loss per share for all periods presented because of their antidilutive effect consisted of the following:

	Year Ended December 31,
	2020		2019		2018
Outstanding stock options		4,248,193		4,104,450		3,075,349
Non-vested restricted stock units		767,271		1,269,300		—
Stock purchase warrants		29,796		29,796		29,796
		5,045,260		5,403,546		3,105,145

Related Party Transactions

12 Months Ended

Dec. 31, 2020

15. Related Party Transactions

On November 22, 2019, the Company issued shares of common stock in a private placement offering at an offering price of $1.054 per share. Two of the purchasers, Hatteras Venture Partners IV SBIC, LP and Hatteras Venture Partners IV, LP, are affiliated with certain of the Company’s directors and purchased 1,347,629 and 170,397 shares, respectively.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Basis of Presentation

The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Property and Equipment, Net

Debt Discount

Income Taxes

Research and Development Costs

Research and development costs are charged to expense as incurred and include:

•

employee-related expenses, including salaries, benefits, travel and share-based compensation expense for research and development personnel;

•

expenses incurred under agreements with contract research organizations, contract manufacturing organizations and consultants that conduct preclinical studies and clinical trials;

•

costs associated with preclinical and clinical development activities;

•

costs associated with submitting regulatory approval applications for the Company’s product candidates;

•

costs associated with training physicians on the suprachoroidal injection procedure and educating and providing them with appropriate product candidate information;

•

costs associated with technology and intellectual property licenses;

•

costs for the Company’s research and development facility; and

•

depreciation expense for assets used in research and development activities.

Share-Based Compensation

Cash Equivalents

Cash equivalents consist of short-term, highly liquid investments with an original term of three months or less at the date of purchase.

Restricted Cash

Concentration of Credit Risk Arising From Cash Deposits in Excess of Insured Limits

Recent Accounting Pronouncements

Accounting Pronouncements Recently Adopted

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2020

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment, Net

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

	Estimated Useful Lives (Years)	December 31,
		2020			2019
Furniture and fixtures	5	$	337		$	337
Machinery and equipment	5		176			121
Computer equipment	3		13			13
Leasehold improvements	Lesser of useful life or remaining lease term		667			667
Total property and equipment			1,193			1,138
Less: Accumulated depreciation			(777	)		(597	)
Property and equipment, net		$	416		$	541

Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Payables And Accruals [Abstract]

Schedule of Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Accrued research and development	$	234	$	359
Accrued employee costs		1,132		1,530
Accrued severance		—		751
Accrued professional fees		56		58
Accrued expense		160		232
	$	1,582	$	2,930

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Share-based Compensation Expense

The total share-based compensation expense recognized is reflected in the statements of operations as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018

Research and development	$	1,183	$	1,379	$	1,766
General and administrative		1,574		2,728		3,004
Total	$	2,757	$	4,107	$	4,770

Weighted Average Assumptions Used in Black-Scholes Option Pricing Model to Calculate Fair Value of Underlying Common Stock

	Year Ended December 31,
	2020			2019			2018

Expected term (years)		7.00			7.00			7.00
Expected stock price volatility		108.13	%		109.49	%		93.08	%
Risk-free interest rate		1.52	%		2.49	%		2.87	%
Expected dividend yield		0.00	%		0.00	%		0.00	%

Summary of Activity Related to Stock Options

The following table summarizes the activity related to stock options during the year ended December 31, 2020:

				Weighted
	Number of			Average
	Shares			Exercise Price

Options outstanding at December 31, 2019		4,104,450		$	4.63
Granted		1,100,250			2.31
Exercised		(254,466	)		0.89
Cancelled/Forfeited		(702,041	)		6.49
Options outstanding at December 31, 2020		4,248,193			3.95

Options exercisable at December 31, 2019		2,452,764			5.44

Options exercisable at December 31, 2020		2,355,900			4.96

Additional Information about the Stock Option Outstanding and Exercisable

The following table provides additional information about the Company’s stock options that were outstanding and exercisable at December 31, 2020 (aggregate intrinsic values in thousands):

							Weighted								Weighted
			Weighted				Average				Weighted				Average
			Average		Aggregate		Remaining				Average		Aggregate		Remaining
Exercise	Options		Exercise		Intrinsic		Contractual		Options		Exercise		Intrinsic		Contractual
Price	Outstanding		Price		Value		Life (Years)		Exercisable		Price		Value		Life (Years)

$0.00 - $2.99		2,598,987						8.12		1,011,680					7.08
$3.00 - $6.99		998,120					6.59			725,221					6.25
$7.00 - $8.99		449,308					6.16			432,847					6.12
$9.00 - $20.84		201,778						6.76		186,152					6.71
		4,248,193	$	3.95	$	2,753	7.49			2,355,900	$	4.96	$	1,551	6.62

2016 Employee Stock Purchase Plan

Summary of Share-based Compensation Expense

The share-based compensation expense recognized for the 2016 ESPP is reflected in the statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018
Research and development	$	19	$	11	$	5
General and administrative		22		9		10
Total	$	41	$	20	$	15

Restricted Stock Units (RSUs)

Summary of the Activity Related to RSUs

The following table summarizes the activity related to RSUs during the year ended December 31, 2020:

				Weighted Average
	Number of			Grant Date
	Shares			Fair Value
Non-vested RSUs outstanding at December 31, 2019		1,269,300		$	0.87
Granted		486,000			2.39
Vested		(981,329	)		0.91
Forfeited		(6,700	)		0.91
Non-vested RSUs outstanding at December 31, 2020		767,271			1.78

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Net Deferred Tax Assets

Significant components of the Company’s net deferred income tax assets consist of the following (in thousands):

	December 31,
	2020			2019			2018
Deferred tax asset (liability)
Net operating loss carryforwards	$	51,414		$	46,305		$	41,152
Non-deductible accrued expenses		263			422			245
Right-of-use asset		(132	)		(138	)		-
Lease liability		247			264			-
Deferred rent		—			—			148
Deferred revenue		1,247			—			—
Stock compensation expense		2,044			1,472			899
Depreciation differences		(82	)		(94	)		(125	)
Federal tax credits		8,015			7,249			6,481
State tax credits		381			623			757
Disallowed interest expense		7			99			—
Charitable contributions		—			4			6
Valuation allowance		(63,404	)		(56,206	)		(49,563	)
Net deferred tax asset	$	—		$	—		$	—

Schedule of Statutory and Effective Income Tax Rate Reconciliation

A reconciliation of the statutory tax rates and the effective tax rates is as follows:

	Year Ended December 31,
	2020			2019			2018
U.S. federal tax rate		21.00	%		21.00	%		21.00	%
State tax rate		14.28			—			(0.73	)
Permanent difference and other		1.42			(1.33	)		(0.33	)
Tax credit		2.89			2.06			3.96
Valuation allowance		(39.66	)		(21.73	)		(20.39	)
ASC 740-10		(0.26	)		—			(4	)
Impact of federal rate change		—			—			—
		0.33	%		0.00	%		0.00	%

Summary of Activity Related to Uncertain Tax Positions

The following is a rollforward of the Company’s uncertain tax positions (in thousands):

	Year Ended December 31,
	2020		2019
Balance of uncertain tax positions at the beginning of the year	$	2,903	$	2,903
Gross increases - tax positions in prior period		4,665		—
Balance of uncertain tax positions at the end of the year	$	7,568	$	2,903

Commitment and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Operating Leases Included on the Balance Sheet

The Company’s operating leases included on the balance sheet are as follows (in thousands):

	December 31, 2020
Operating lease right-of-use asset	$	528

Liabilities
Current portion of operating lease liabilities	$	373
Operating lease liabilities		616
Total operating lease liabilities	$	989

Future Minimum Commitments Due Under Non-Cancelable Operating Leases

Minimum lease payments were as follows at December 31, 2020 (in thousands):

Year ending December 31,
2021	$	392
2022		407
2023		316
Total minimum lease payments		1,115
Less imputed interest		(126	)
Total operating lease liabilities	$	989

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Summary of Assets and Liabilities Measured at Fair Value

	December 31, 2020
	Level 1		Level 2		Level 3		Recorded Value
Financial Assets:
Cash and money markets	$	17,287	$	—	$	—	$	17,287
Restricted cash money market		360		—		—		360
Total financial assets	$	17,647	$	—	$	—	$	17,647

	December 31, 2019
	Level 1		Level 2		Level 3		Recorded Value
Financial Assets:
Cash and money markets	$	22,595	$	—	$	—	$	22,595
Restricted cash money market		360		—		—		360
Total financial assets	$	22,955	$	—	$	—	$	22,955

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Potential Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share

	Year Ended December 31,
	2020		2019		2018
Outstanding stock options		4,248,193		4,104,450		3,075,349
Non-vested restricted stock units		767,271		1,269,300		—
Stock purchase warrants		29,796		29,796		29,796
		5,045,260		5,403,546		3,105,145

The Company - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jan. 06, 2021	Jan. 01, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Entity incorporation date			May 26, 2011
Cash and cash equivalents			$ 17,287	$ 22,595	$ 8,043
Common Stock
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Purchase of common stock by institutional purchasers				3,178,367
Private Placement \| Common Stock \| Subsequent Event
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Purchase of common stock by institutional purchasers	4,200,000
Purchase price per share	$ 2.851
Net proceeds after deducting offering expenses	$ 11,100
At-the-market Sales Agreement \| Cowen and Company LLC \| Common Stock \| Subsequent Event
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of shares sold under facility		1,200,000
Net proceeds from issuance of stock		$ 3,300

Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020 Segment
Accounting Policies [Abstract]
Number of operating segments	1

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment	$ 1,193	$ 1,138
Less: Accumulated depreciation	(777)	(597)
Property and equipment, net	416	541
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	$ 337	337
Estimated Useful Lives (Years)	5 years
Machinery and Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 176	121
Estimated Useful Lives (Years)	5 years
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 13	13
Estimated Useful Lives (Years)	3 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 667	$ 667
Estimated Useful Lives (Years)	Lesser of useful life or remaining lease term

Accrued Liabilities - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued research and development	$ 234	$ 359
Accrued employee costs	1,132	1,530
Accrued severance		751
Accrued professional fees	56	58
Accrued expense	160	232
Accrued liabilities, current	$ 1,582	$ 2,930

Long-Term Debt - Additional Information (Details) - USD ($)				12 Months Ended
	May 07, 2020	Oct. 18, 2019	May 14, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Interest expense on borrowings				$ 147,000	$ 804,000	$ 791,000
Accretion of scheduled final payment				59,000	163,000	154,000
Accretion of deferred closing costs				$ 129,000	$ 67,000	$ 112,000
Second Amended and Restated Loan and Security Agreement
Debt Instrument [Line Items]
Debt instrument, principal balance payment	$ 5,000,000
Debt Instrument, Final Payment, Interest	$ 300,000
Third Amended And Restated Loan And Security Agreement
Debt Instrument [Line Items]
Debt instrument, payment terms				On October 18, 2019, the Company entered into an amendment to the 2nd A&R Loan Agreement with the Lenders. Pursuant to the amendment, the Company repaid $5.0 million of the outstanding principal balance of the $10.0 million term loan. The Company did not pay any final payment or termination fees in connection with the $5.0 million prepayment. In addition, the Company and the Lenders agreed to modify the term loan repayment schedule. As amended, the term loan repayment schedule provided for interest only payments through October 31, 2020, followed by consecutive equal monthly payments of principal and interest in arrears continuing through the maturity date of October 1, 2022.
Silicon Valley Bank, MidCap Funding III Trust and MidCap Financial Trust \| Second Amended and Restated Loan and Security Agreement
Debt Instrument [Line Items]
Fixed interest rate			6.50%
Variable interest rate			1.89%
Debt instrument, description of variable rate basis				30-day U.S. LIBOR
Line of credit facility, maximum borrowing capacity			$ 20,000,000
Long term debt			10,000,000
Line of credit facility, remaining borrowing capacity description				Of the remaining $10.0 million available under the 2nd A&R loan agreement, the Company elected not to draw $5.0 million and the other $5.0 million was not available for draw.
Line of credit facility remaining borrowing capacity not available for withdraw			5,000,000
Line of credit facility, remaining borrowing capacity			5,000,000
Silicon Valley Bank, MidCap Funding III Trust and MidCap Financial Trust \| Second Amended and Restated Loan and Security Agreement, Initial Tranche
Debt Instrument [Line Items]
Long term debt			10,000,000
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust \| First Amended and Restated Loan and Security Agreement \| Final Payment
Debt Instrument [Line Items]
Repayment of outstanding amount under the loan agreement including fees			$ 7,000,000
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust \| Third Amended And Restated Loan And Security Agreement
Debt Instrument [Line Items]
Long term debt		$ 10,000,000
Repayment of outstanding amount under the loan agreement including fees		$ 5,000,000
Loans held-for-sale, maturity date		Oct. 01, 2022
Final payment during maturity, percentage				5.50%

CARES Act Paycheck Protection Program Loan - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Apr. 20, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Short Term Debt [Line Items]
Current portion of long-term debt		$ 991,000	$ 1,333,000
Interest expense on borrowings		147,000	$ 804,000	$ 791,000
PPP Loan
Short Term Debt [Line Items]
Current portion of long-term debt		1,000,000
Interest expense on borrowings		$ 7,000
PPP Loan \| Silicon Valley Bank
Short Term Debt [Line Items]
Aggregate principal amount	$ 1,000,000
Interest rate on outstanding principal amount	1.00%
Note, Maturity date	Apr. 30, 2022
PPP Loan \| Silicon Valley Bank \| Minimum
Short Term Debt [Line Items]
Eligible Payroll Costs	60.00%

Preferred and Common Stock - Additional Information (Detail) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Equity [Abstract]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares outstanding	51,860,941	44,413,372

Common Stock Warrants - Additional Information (Details) - Convertible Stock Warrant - $ / shares	1 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2020
Class Of Warrant Or Right [Line Items]
Class of warrant Exercise	$ 10.74
Warrants expiration term	2026-09
Weighted average remaining life of warrants		5 years 9 months
Maximum [Member]
Class Of Warrant Or Right [Line Items]
Number of stock that can be purchased by each warrant	29,796

Share-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Jan. 01, 2021	Jan. 31, 2016	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
2016 Stock Incentive Plan \| Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increase of common stock reserved for issuance	4.00%
Increase in common stock for future issuance, shares	2,074,437,000
Shares common stock reserved for issuance	3,143,038,000
2016 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation arrangement description			The number of shares reserved for issuance under the 2016 ESPP will automatically increase on January 1 of each year, through January 1, 2026, by the lesser of (i) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, (ii) 454,545 shares of common stock or (iii) a lesser number of shares as may be determined by the Company’s board of directors
Annual increase of common stock reserved for issuance		1.00%
Shares common stock reserved for issuance			570,972
Employee payroll deductions, percent		15.00%
Addition of common stock shares reserved for future issuance		454,545
Common stock purchased			35,359	52,476	12,595
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares grants			1,100,250
Option to purchase common stock shares outstanding			4,248,193	4,104,450
Weighted average exercise price			$ 3.95	$ 4.63
Unrecognized compensation expense related to unvested stock options			$ 3.4
Expected to be recognized over a weighted average period			2 years 1 month 6 days
Weighted-average fair values granted			$ 1.97	$ 1.09	$ 5.98
Fair market value per share of common stock			$ 2.74
Stock Options \| 2016 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation arrangement description			The number of shares of common stock reserved for issuance under the 2016 Plan will automatically increase on January 1 each year, through January 1, 2026, by 4% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors.
Annual increase of common stock reserved for issuance			4.00%
Option to purchase common stock shares outstanding			3,794,184
Weighted average exercise price			$ 4.09
Shares available for future grant			1,068,601
Stock Options \| 2011 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares grants			0
Option to purchase common stock shares outstanding			436,773
Weighted average exercise price			$ 2.53
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected to be recognized over a weighted average period			2 years 6 months
Unrecognized compensation expense related to the RSUs			$ 1.0

Share-Based Compensation - Summary of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
2016 Employee Stock Purchase Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 41	$ 20	$ 15
Research and Development \| 2016 Employee Stock Purchase Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	19	11	5
General and Administrative \| 2016 Employee Stock Purchase Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	22	9	10
Stock Options
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	2,757	4,107	4,770
Stock Options \| Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	1,183	1,379	1,766
Stock Options \| General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	1,574	2,728	$ 3,004
Restricted Stock Units (RSUs)
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	802	483
Restricted Stock Units (RSUs) \| Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	375	177
Restricted Stock Units (RSUs) \| General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 427	$ 306

Share-Based Compensation - Weighted Average Assumptions Used in Black-Scholes Option Pricing Model to Calculate Fair Value of Underlying Common Stock (Details) - Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Expected term (years)	7 years	7 years	7 years
Expected stock price volatility	108.13%	109.49%	93.08%
Risk-free interest rate	1.52%	2.49%	2.87%
Expected dividend yield	0.00%	0.00%	0.00%

Share-Based Compensation - Summary of Activity Related to Stock Options (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Options outstanding, Beginning balance	4,104,450
Number of Shares, Granted	1,100,250
Number of Shares, Exercised	(254,466)
Number of Shares, Cancelled/Forfeited	(702,041)
Number of Shares, Options outstanding, Ending balance	4,248,193	4,104,450
Number of Shares, Options exercisable	2,355,900	2,452,764
Weighted Average Exercise Price, Options outstanding, Beginning balance	$ 4.63
Weighted Average Exercise Price, Granted	2.31
Weighted Average Exercise Price, Exercised	0.89
Weighted Average Exercise Price, Cancelled/Forfeited	6.49
Weighted Average Exercise Price, Options outstanding, Ending balance	3.95	$ 4.63
Weighted Average Exercise Price, Options exercisable	$ 4.96	$ 5.44

Share-Based Compensation - Additional Information about the Stock Option Outstanding and Exercisable (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	4,248,193	4,104,450
Weighted Average Exercise Price	$ 3.95	$ 4.63
Aggregate Intrinsic Value	$ 2,753
Weighted Average Remaining Contractual Life (Years)	7 years 5 months 26 days
Options Exercisable	2,355,900	2,452,764
Weighted Average Exercise Price	$ 4.96	$ 5.44
Aggregate Intrinsic Value	$ 1,551
Weighted Average Remaining Contractual Life (Years)	6 years 7 months 13 days
$0.00 - $2.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 0.00
Exercise Price Upper Range Limit	$ 2.99
Options Outstanding	2,598,987
Weighted Average Remaining Contractual Life (Years)	8 years 1 month 13 days
Options Exercisable	1,011,680
Weighted Average Remaining Contractual Life (Years)	7 years 29 days
$3.00 - $6.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 3.00
Exercise Price Upper Range Limit	$ 6.99
Options Outstanding	998,120
Weighted Average Remaining Contractual Life (Years)	6 years 7 months 2 days
Options Exercisable	725,221
Weighted Average Remaining Contractual Life (Years)	6 years 3 months
$7.00 - $8.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 7.00
Exercise Price Upper Range Limit	$ 8.99
Options Outstanding	449,308
Weighted Average Remaining Contractual Life (Years)	6 years 1 month 28 days
Options Exercisable	432,847
Weighted Average Remaining Contractual Life (Years)	6 years 1 month 13 days
$9.00 - $20.84
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 9.00
Exercise Price Upper Range Limit	$ 20.84
Options Outstanding	201,778
Weighted Average Remaining Contractual Life (Years)	6 years 9 months 3 days
Options Exercisable	186,152
Weighted Average Remaining Contractual Life (Years)	6 years 8 months 15 days

Share-Based Compensation - Summary of the Activity Related to RSUs (Details) - Restricted Stock Units (RSUs)	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-vested units outstanding, Number of Shares, Beginning balance \| shares	1,269,300
Number of Shares, Granted \| shares	486,000
Number of Shares, Vested \| shares	(981,329)
Number of Shares, Forfeited \| shares	(6,700)
Non-vested units outstanding, Number of Shares, Ending balance \| shares	767,271
Non-vested units outstanding, Weighted Average Grant Date Fair Value, Beginning balance \| $ / shares	$ 0.87
Weighted Average Grant Date Fair Value, Granted \| $ / shares	2.39
Weighted Average Grant Date Fair Value, Vested \| $ / shares	0.91
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	0.91
Non-vested units outstanding, Weighted Average Grant Date Fair Value, Ending balance \| $ / shares	$ 1.78

Income Taxes - Schedule of Net Deferred Tax Assets (Detail) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax asset (liability)
Net operating loss carryforwards	$ 51,414,000	$ 46,305,000	$ 41,152,000
Non-deductible accrued expenses	263,000	422,000	245,000
Right-of-use asset	(132,000)	(138,000)
Lease liability	247,000	264,000
Deferred rent			148,000
Deferred revenue	1,247,000
Stock compensation expense	2,044,000	1,472,000	899,000
Depreciation differences	(82,000)	(94,000)	(125,000)
Disallowed interest expense	7,000	99,000
Charitable contributions		4,000	6,000
Valuation allowance	(63,404,000)	(56,206,000)	(49,563,000)
Federal
Deferred tax asset (liability)
Net operating loss carryforwards	48,900,000
Tax credits	8,015,000	7,249,000	6,481,000
State
Deferred tax asset (liability)
Net operating loss carryforwards	2.5
Tax credits	$ 381,000	$ 623,000	$ 757,000

Schedule of Statutory and Effective Income Tax Rate Reconciliation (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
U.S. federal tax rate	21.00%	21.00%	21.00%
State tax rate	14.28%		(0.73%)
Permanent difference and other	1.42%	(1.33%)	(0.33%)
Tax credit	2.89%	2.06%	3.96%
Valuation allowance	(39.66%)	(21.73%)	(20.39%)
ASC 740-10	(0.26%)		(4.00%)
Total income tax provision (benefit)	0.33%	0.00%	0.00%

Income Tax - Additional Information (Detail) - USD ($)	12 Months Ended
Income Tax - Additional Information (Detail) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	$ 63,404,000	$ 56,206,000	$ 49,563,000
Deferred tax assets, net operating loss carryforwards	51,414,000	46,305,000	$ 41,152,000
Unrecognized tax benefits that would affect the effective tax rate if recognized	7,600,000	$ 2,900,000
Unrecognized tax benefits accrued	4,600,000
Unrecognized tax expenses	48,000,000,000
Unrecognized tax benefits, interest on income taxes	0
Unrecognized tax benefits, income tax penalties expense	0
Uncertain tax positions, interest and penalties unrecognized	$ 0
Operating loss carryforwards, limitations on use	Ownership changes, as defined by Section 382 of the Internal Revenue Code of 1986, as amended (the “Code”), may limit the amount of net operating losses that a company may utilize to offset future taxable income and taxes payable. Pursuant to Section 382 of the Code, an ownership change occurs when the stock ownership of 5% stockholders increases by more than 50% over a testing period of three years. It is possible that the Company has undergone an ownership change as defined by Section 382 of the Code or that the Company may undergo such a change in the future. Any such ownership change may limit the Company’s ability to utilize net operating losses.
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 232,700,000
Deferred tax assets, net operating loss carryforwards	$ 48,900,000
Federal \| Earliest Tax Year
Income Tax Disclosure [Line Items]
Operating loss carryforwards expiration period	2031
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 40,700,000
Deferred tax assets, net operating loss carryforwards	$ 2.5
State \| Earliest Tax Year
Income Tax Disclosure [Line Items]
Operating loss carryforwards expiration period	2027

Summary of Activity Related to Uncertain Tax Positions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Summary of activity related to uncertain tax positions
Balance of uncertain tax positions at the beginning of the year	$ 2,903	$ 2,903
Gross increases - tax positions in prior period	4,665	0
Balance of uncertain tax positions at the end of the year	$ 7,568	$ 2,903

Commitment and Contingencies - Additional Information (Details)	1 Months Ended			12 Months Ended
	Aug. 31, 2018 USD ($) ft²	May 31, 2018	Nov. 30, 2016 USD ($) ft²	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Commitment And Contingencies [Line Items]
Lessee, operating lease, option to extend, description				The renewal option is not included in the calculation of the right-of-use asset and the lease liabilities as the Company has not yet determined if the Alpharetta, Georgia lease will be renewed.
Incremental borrowing rate				11.00%
Operating lease, remaining lease term				2 years 9 months
Operating Lease, Cost				$ 247,000	$ 393,000
Variable Lease, Cost				95,000	83,000
Short-term Lease, Cost				$ 12,000	$ 20,000
Manufacturing Supply Agreement \| Gerresheimer Regensburg GmbH
Commitment And Contingencies [Line Items]
Initial term of agreement		5 years
Renewal term of agreement		3 years
GEORGIA
Commitment And Contingencies [Line Items]
Area of office leased \| ft²			20,000
Operating lease agreement term			6 years 6 months
Operating lease agreement renewal option term			5 years
Minimum monthly lease payments			$ 35,145
Percentage of increase per year			3.00%
CALIFORNIA
Commitment And Contingencies [Line Items]
Area of office leased \| ft²	3,500
Operating lease agreement term	2 years
Operating lease agreement renewal option term	1 year
Lease termination date	Dec. 15, 2019
Operating lease liability payments due	$ 0

Commitment and Contingencies - Operating Leases Included on the Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Operating lease right-of-use asset	$ 528	$ 656
Liabilities
Current portion of operating lease liabilities	373	360
Operating lease liabilities	616	$ 897
Total operating lease liabilities	$ 989

Commitment and Contingencies - Future Minimum Commitments Due Under Non-Cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2021	$ 392
2022	407
2023	316
Total minimum lease payments	1,115
Less imputed interest	(126)
Total operating lease liabilities	$ 989

License and Other Agreements - Additional Information (Detail) - USD ($)			1 Months Ended			12 Months Ended
	Mar. 10, 2020	Oct. 22, 2019	Sep. 30, 2020	Mar. 31, 2020	Oct. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Research And Development Arrangement Contract To Perform For Others [Line Items]
Deferred revenue						$ 5,000,000	$ 5,000,000
Revenue						7,894,000	2,173,000	$ 30,000
Other Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue						200,000	105,000	$ 30,000
License Arrangement \| REGENXBIO, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Option fee paid					$ 2,000,000
Proceeds from option fee previously received					500,000
Milestone payments					34,000,000
Sales-based milestone payments					$ 102,000,000
Milestone payments received			$ 3,000,000
Bausch Health Ireland Limited
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront payment		$ 5,000,000
First cumulative net sales of products		45,000,000
Bausch Health Ireland Limited \| Upfront payment
Research And Development Arrangement Contract To Perform For Others [Line Items]
Deferred revenue						$ 5,000,000	$ 5,000,000
Bausch Health Ireland Limited \| Commercial Arrangement \| Maximum [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Pre-launch milestone payments		15,000,000
Additional milestone payments		$ 57,300,000
Arctic Vision Limited
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront payment	$ 4,000,000
Amount of upfront payment and development milestones payment to be received under license agreement	35,500,000
Upfront payment received				$ 4,000,000
Arctic Vision Limited \| Maximum [Member]
Research And Development Arrangement Contract To Perform For Others [Line Items]
Development milestone payments	$ 31,500,000
Threshold percentage of sales for tiered royalties	12.00%
Arctic Vision Limited \| Minimum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Threshold percentage of sales for tiered royalties	10.00%

Fair Value Measurements - Additional Information (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Significant transfers between Levels 1, 2 and 3	$ 0	$ 0

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financial Assets:
Total financial assets	$ 17,647	$ 22,955
Level 1
Financial Assets:
Total financial assets	17,647	22,955
Cash and Money Markets
Financial Assets:
Total financial assets	17,287	22,595
Cash and Money Markets \| Level 1
Financial Assets:
Total financial assets	17,287	22,595
Restricted Cash Money Market
Financial Assets:
Total financial assets	360	360
Restricted Cash Money Market \| Level 1
Financial Assets:
Total financial assets	$ 360	$ 360

Net Loss Per Share - Potential Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	5,045,260	5,403,546	3,105,145
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	4,248,193	4,104,450	3,075,349
Non-vested Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	767,271	1,269,300
Stock Purchase Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	29,796	29,796	29,796

Related Party Transactions (Detail) - Private Placement	Nov. 22, 2019 $ / shares shares
Related Party Transaction [Line Items]
Shares issued, price per share \| $ / shares	$ 1.054
Hatteras venture partners IV SBIC, LP
Related Party Transaction [Line Items]
Shares, issued	1,347,629
Hatteras venture partners IV, LP
Related Party Transaction [Line Items]
Shares, issued	170,397