Ocular Therapeutix (OCUL) 10-K 12 Mar 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Mar. 02, 2020	Jun. 28, 2019
Document And Entity Information [Abstract]
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Entity Registrant Name	Ocular Therapeutix, Inc.
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		52,576,940
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0001393434
Amendment Flag	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 169

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 54,437	$ 54,062
Accounts receivable, net	2,548	201
Inventory	954	217
Prepaid expenses and other current assets	2,231	1,713
Total current assets	60,170	56,193
Property and equipment, net	10,151	10,236
Restricted cash	1,764	6,614
Operating lease assets	6,655
Total assets	78,740	73,043
Current liabilities:
Accounts payable	3,268	2,965
Accrued expenses and other current liabilities	7,635	6,194
Operating lease liabilities	1,126
Total current liabilities	12,029	9,159
Other liabilities		3,221
Operating lease liabilities, net of current portion	8,905
Derivative liability	12,124
Notes payable, net of discount	25,007	24,788
2026 convertible notes, net	24,305
Total liabilities	82,370	37,168
Commitments and contingencies (Note 15)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized and no shares issued or outstanding at December 31, 2019 and December 31, 2018, respectively
Common stock, $0.0001 par value; 100,000,000 shares authorized and 50,333,559 and 41,518,091 shares issued and outstanding at December 31, 2019 and December 31, 2018, respectively	5	4
Additional paid-in capital	379,980	333,114
Accumulated deficit	(383,615)	(297,243)
Total stockholders’ equity (deficit)	(3,630)	35,875
Total liabilities and stockholders’ equity (deficit)	$ 78,740	$ 73,043

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Consolidated Balance Sheets
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	50,333,559	41,518,091
Common stock, shares outstanding	50,333,559	41,518,091

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue:
Revenue, Product and Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Total revenue, net	$ 4,227	$ 1,990	$ 1,923
Costs and operating expenses:
Cost, Product and Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Cost of product revenue	$ 2,325	$ 465	$ 457
Research and development	41,091	36,915	30,880
Selling and marketing	24,491	4,942	17,000
General and administrative	22,122	18,786	15,509
Total costs and operating expenses	90,029	61,108	63,846
Loss from operations	(85,802)	(59,118)	(61,923)
Other income (expense):
Interest income	1,229	879	424
Interest expense	(6,101)	(1,739)	(1,892)
Change in fair value of derivative liability	4,310
Other income (expense), net	(8)		5
Total other income (expense), net	(570)	(860)	(1,463)
Net loss and comprehensive loss	$ (86,372)	$ (59,978)	$ (63,386)
Net loss per share, basic and diluted	$ (1.91)	$ (1.57)	$ (2.20)
Weighted average common shares outstanding, basic and diluted	45,273,231	38,115,142	28,818,196
Comprehensive loss:
Net loss	$ (86,372)	$ (59,978)	$ (63,386)
Other comprehensive loss:
Unrealized gain on marketable securities			5
Total other comprehensive income			5
Total comprehensive loss	$ (86,372)	$ (59,978)	$ (63,381)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Total
Balance at Dec. 31, 2016	$ 3	$ 225,889	$ (173,879)	$ (5)	$ 52,008
Balance, shares at Dec. 31, 2016	25,024,100
Stockholders' Equity
Issuance of common stock upon exercise of stock options		685			685
Issuance of common stock upon exercise of stock options, shares	220,520
Issuance of common stock in connection with employee stock purchase plan		276			276
Issuance of common stock in connection with employee stock purchase plan, shares	53,662
Issuance of common stock upon public offering, net of issuance costs		29,238			29,238
Issuance of common stock upon public offering, net of issuance costs, shares	4,359,920
Unrealized gain on marketable securities				$ 5	5
Stock-based compensation expense		7,321			7,321
Net loss			(63,386)		(63,386)
Balance at Dec. 31, 2017	$ 3	263,409	(237,265)		26,147
Balance, shares at Dec. 31, 2017	29,658,202
Stockholders' Equity
Issuance of common stock upon exercise of stock options		397			397
Issuance of common stock upon exercise of stock options, shares	182,261
Issuance of common stock in connection with employee stock purchase plan		297			297
Issuance of common stock in connection with employee stock purchase plan, shares	81,455
Issuance of common stock upon public offering, net of issuance costs	$ 1	61,528			61,529
Issuance of common stock upon public offering, net of issuance costs, shares	11,596,173
Stock-based compensation expense		7,483			7,483
Net loss			(59,978)		(59,978)
Balance at Dec. 31, 2018	$ 4	333,114	(297,243)		35,875
Balance, shares at Dec. 31, 2018	41,518,091
Stockholders' Equity
Issuance of common stock upon exercise of stock options		78			$ 78
Issuance of common stock upon exercise of stock options, shares	28,583				28,583
Issuance of common stock in connection with employee stock purchase plan		451			$ 451
Issuance of common stock in connection with employee stock purchase plan, shares	130,945
Issuance of common stock upon public offering, net of issuance costs	$ 1	37,578			37,579
Issuance of common stock upon public offering, net of issuance costs, shares	8,655,940
Stock-based compensation expense		8,759			8,759
Net loss			(86,372)		(86,372)
Balance at Dec. 31, 2019	$ 5	$ 379,980	$ (383,615)		$ (3,630)
Balance, shares at Dec. 31, 2019	50,333,559

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (86,372)	$ (59,978)	$ (63,386)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation expense	8,759	7,483	7,321
Non-cash interest expense	3,683	397	408
Change in fair value of derivative liability	(4,310)
Depreciation and amortization expense	2,530	2,286	1,625
(Gain)/loss on disposal of property and equipment	7		(5)
Purchase of premium on marketable securities			(3)
Amortization of premium on marketable securities			17
Changes in operating assets and liabilities:
Accounts receivable	(2,347)	25	24
Prepaid expenses and other current assets	(518)	(260)	45
Inventory	(737)	(95)	(9)
Operating lease assets	733
Accounts payable	124	(796)	932
Accrued expenses and deferred rent	1,714	1,711	2,558
Operating lease liabilities	(844)
Net cash used in operating activities	(77,578)	(49,227)	(50,473)
Cash flows from investing activities:
Purchases of property and equipment	(2,238)	(1,889)	(8,252)
Proceeds from sale of property and equipment			5
Purchases of marketable securities			(3,000)
Proceeds from maturities of marketable securities			38,200
Net cash (used in) provided by investing activities	(2,238)	(1,889)	26,953
Cash flows from financing activities:
Proceeds from issuance of notes payable		12,032	3,700
Proceeds from issuance of 2026 convertible notes, net of issuance costs	37,275
Proceeds from exercise of stock options	78	397	685
Proceeds from issuance of common stock pursuant to employee stock purchase plan	451	297	276
Proceeds from issuance of common stock offering, net	37,537	61,571	29,238
Payments of insurance costs financed by a third party			(591)
Repayment of notes payable		(5,657)	(1,300)
Net cash provided by financing activities	75,341	68,640	32,008
Net increase (decrease) in cash, cash equivalents and restricted cash	(4,475)	17,524	8,488
Cash, cash equivalents and restricted cash at beginning of period	60,676	43,152	34,664
Cash, cash equivalents and restricted cash at end of period	56,201	60,676	43,152
Supplemental disclosure of cash flow information:
Cash paid for interest	2,298	1,515	1,461
Supplemental disclosure of non-cash investing and financing activities:
Additional right of use asset and related lease liability	2,044
Additions to property and equipment included in accounts payable and accrued expenses at balance sheet dates	214	155	538
Derivative liability in connection with issuance of 2026 convertible notes	$ 16,434
Public offering costs included in accounts payable and accrued expenses at balance sheet dates		$ 42	$ 108

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2019
Nature of the Business and Basis of Presentation
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation Ocular Therapeutix, Inc. (the “Company”) was incorporated on September 12, 2006 under the laws of the State of Delaware. The Company is a biopharmaceutical company focused on the formulation, development and commercialization of innovative therapies for diseases and conditions of the eye using its proprietary, bioresorbable hydrogel platform technology. The Company’s product pipeline candidates provide differentiated drug delivery solutions that reduce the complexity and burden of the current standard of care (eye drops) by creating local programmed-release alternatives. Since inception, the Company’s operations have been primarily focused on organizing and staffing the Company, acquiring rights to intellectual property, business planning, raising capital, developing its technology, identifying potential product candidates, undertaking preclinical studies and clinical trials, manufacturing initial quantities of its products and product candidates and building the initial sales and marketing infrastructure for the commercialization of the Company’s approved products and product candidates and launching its initial product. The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations, regulatory approval and compliance, reimbursement, uncertainty of market acceptance of products and the need to obtain additional financing. Recently approved products will require significant sales, marketing and distribution support up to and including upon their launch. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization. As of December 31, 2019, the Company’s lead product candidate DEXTENZA ® (dexamethasone insert) 0.4mg, has been approved by the FDA and the Company’s other product candidates are in clinical stage development. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained, that any products developed will obtain necessary government regulatory approval and adequate reimbursement or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapidly changing technology and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees and consultants. The Company may not be able to generate significant revenue from sales of any product for several years, if at all. Accordingly, the Company will need to obtain additional capital to finance its operations. Based on the Company’s current forecasted operating plan, which includes estimates related to anticipated cash inflows from DEXTENZA and ReSure Sealant product sales, and cash outflows for operating expenses, the Company believes that its existing cash and cash equivalents of $54,437, as of December 31, 2019 along with the net proceeds received from sales of common stock in 2020 under sales agreement (Note 22), will enable it to fund its planned operating expenses, debt service obligations and capital expenditure requirements into the first quarter of 2021. The Company has a limited history of commercialization of DEXTENZA, and management does not yet have sufficient historical evidence to assert that it is probable that the Company will receive sufficient revenues from its sales of DEXTENZA to fund operations. Therefore, management has determined that the Company’s accumulated deficit, history of losses, negative cash flows from operations and future expected losses raise substantial doubt about the Company’s ability to continue as a going concern within one year of the issuance date of these financial statements. The Company has incurred losses and negative cash flows from operations since its inception, and the Company expects to continue to generate operating losses and negative cash flows from operations in the foreseeable future. As of December 31, 2019, the Company had an accumulated deficit of $383,615. While the Company has raised capital in the past, the ability to raise capital in future periods is not considered probable, as defined under the accounting standards and therefore, was not considered in management’s assessment of the Company’s ability to continue as a going concern. The Company expects to seek additional funds through equity offerings, debt financings The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”).

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements reflect the operations of the Company and its wholly-owned subsidiary. All intercompany accounts and transactions have been eliminated. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition, and the fair value of derivatives. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates. Cash Equivalents The Company considers all short-term, highly liquid investments with original maturities of ninety days or less at date of purchase to be cash equivalents. Cash equivalents, which primarily consist of money market accounts, are stated at fair value. Revenue Recognition The Company recognizes product revenue from DEXTENZA for the treatment of post-surgical ocular inflammation and pain, which it began selling to customers in June 2019, and ReSure Sealant. The Company has generated limited revenues from ReSure Sealant to date and does not expect significant future sales. In November 2018, the FDA approved DEXTENZA for the treatment of ocular pain following ophthalmic surgery . The Company entered into a limited number of arrangements with specialty distributors in the United States to distribute DEXTENZA. The Company recognizes revenue in accordance with Accounting Standards Codification 606 – Revenue from Contracts with Customers (“Topic 606”). Topic 606 applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance arrangements and financial instruments. Under Topic 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to be entitled to in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract, and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to arrangements that meet the definition of a contract with a customer under Topic 606, including when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. For a complete discussion of accounting for product revenue, see Product Revenue, Net (below). Product Revenue, Net — The Company derives its product revenues from the sale of DEXTENZA in the United States to customers, which includes a limited number of specialty distributors, who then subsequently resell DEXTENZA to physicians, clinics and certain medical centers or hospitals. In addition to distribution agreements with customers, the Company enters into arrangements with government payers that provide for government mandated rebates and chargebacks with respect to the purchase of DEXTENZA. The Company recognizes revenue on product sales when the customer obtains control of the Company's product, which occurs at a point in time (upon delivery to the customer). The Company has determined that the delivery of DEXTENZA to its customers constitutes a single performance obligation. There are no other promises to deliver goods or services beyond what is specified in each accepted customer order. The Company has assessed the existence of a significant financing component in the agreements with its customers. The trade payment terms with the Company’s customers do not exceed one year and therefore the Company has elected to apply the practical expedient and no amount of consideration has been allocated as a financing component. Product revenues are recorded net of applicable reserves for variable consideration, including discounts and allowances. Transaction Price, including Variable Consideration — Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration for which reserves are established. Components of variable consideration include trade discounts and allowances, product returns, government chargebacks, discounts and rebates, and other incentives, such as voluntary patient assistance, and other fee-for-service amounts that are detailed within contracts between the Company and its customers relating to the Company’s sale of DEXTENZA. These reserves, as detailed below, are based on the amounts earned, or to be claimed on the related sales, and are classified as reductions of accounts receivable (if the amount is payable to the customer) or a current liability (if the amount is payable to a party other than a customer). These estimates take into consideration a range of possible outcomes which are probability-weighted in accordance with the expected value method in Topic 606 for relevant factors such as current contractual and statutory requirements, specific known market events and trends, industry data, and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the respective underlying contracts. The amount of variable consideration which is included in the transaction price may be constrained, and is included in the net sales price, only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized under the contract will not occur in a future period. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s original estimates, the Company will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. Trade Discounts and Allowances —The Company compensates (through trade discounts and allowances) its customers for sales order management, data, and distribution services. However, the Company has determined such services received to date are not distinct from the Company’s sale of products to the customer and, therefore, these payments have been recorded as a reduction of revenue within the statement of operations and comprehensive loss through December 31, 2019, as well as a reduction to accounts receivables, net on the consolidated balance sheets. Product Returns — Consistent with industry practice, the Company generally offers customers a limited right of return for product that has been purchased from the Company in certain circumstances as further discussed below. The Company estimates the amount of its product sales that may be returned by its customers and records this estimate as a reduction of revenue in the period the related product revenue is recognized, as well as within accrued expenses and other current liabilities, in the accompanying consolidated balance sheets. The Company currently estimates product return reserves using available industry data and its own sales information, including its visibility into the inventory remaining in the distribution channel. The Company has received no returns to date and believes the returns of DEXTENZA will be minimal. The Company’s limited right of return allows for eligible returns of DEXTENZA in the following circumstances: · Shipment errors that were the result of an error by the Company; · Quantity delivered that is greater or less than the quantity ordered; · Product distributed by the Company that is damaged in transit prior to receipt by the customer; · Product from physicians, clinics, medical centers and hospitals that was not administered to the patient that is rendered non-usable due to spoilage or mishandling; · Expired product, previously purchased directly from the Company, that is returned during the period beginning six months prior to the product’s expiration date and ending twelve months after the product’s expiration date; · Product subject to a recall; and · Product that the Company, at its sole discretion, has specified to be returned. Government Chargebacks — Chargebacks for fees and discounts to qualified government healthcare providers represent the estimated obligations resulting from contractual commitments to sell products to qualified U.S. Department of Veterans Affairs hospitals and 340B entities at prices lower than the list prices charged to customers who directly purchase the product from the Company. The 340B Drug Discount Program is a U.S. federal government program created in 1992 that requires drug manufacturers to provide outpatient drugs to eligible health care organizations and covered entities at significantly reduced prices. Customers charge the Company for the difference between what they pay for the product and the statutory selling price to the qualified government entity. These reserves are established in the same period that the related revenue is recognized, resulting in a reduction of product revenue and accounts receivables, net. Chargeback amounts are generally determined at the time of resale to the qualified government healthcare provider by customers, and the Company generally issues credits for such amounts within a few weeks of the Customer’s notification to the Company of the resale. Reserves for chargebacks consist of credits that the Company expects to issue for units that remain in the distribution channel inventories at each reporting period-end that the Company expects will be sold to qualified healthcare providers, and chargebacks that customers have claimed, but for which the Company has not yet issued a credit. Government Rebates — The Company is subject to discount obligations under state Medicaid programs and Medicare. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included in accrued expenses and other current liabilities on the consolidated balance sheets. For Medicare, the Company also estimates the number of patients in the prescription drug coverage gap for whom the Company will owe an additional liability under the Medicare Part D program. For Medicaid programs, the Company estimates the portion of sales attributed to Medicaid patients and records a liability for the rebates to be paid to the respective state Medicaid programs. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimated future claims that will be made for product that has been recognized as revenue, but which remains in the distribution channel inventories at the end of each reporting period. Other Incentives — Other incentives which the Company offers include voluntary patient assistance programs, such as the co-pay assistance program, which are intended to provide financial assistance to qualified commercially-insured patients with prescription drug co-payments required by payers. The calculation of the accrual for co-pay assistance is based on an estimate of claims and the cost per claim that the Company expects to receive associated with product that has been recognized as revenue, but remains in the distribution channel inventories at the end of each reporting period. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included as an accrued expenses and other current liabilities on the consolidated balance sheets. Inventory The Company values its inventories at the lower of cost or estimated net realizable value. The Company determines the cost of its inventories, which includes amounts related to materials and manufacturing overhead, on a first-in, first-out basis. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and it writes down any excess and obsolete inventories to their estimated realizable value in the period in which the impairment is first identified. Such impairment charges, should they occur, are recorded within cost of product revenue. The determination of whether inventory costs will be realizable requires estimates by management. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required, which would be recorded as a cost of product revenue in the consolidated statements of operations and comprehensive loss. The Company capitalizes inventory costs associated with the Company’s products after regulatory approval when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Inventory acquired prior to receipt of marketing approval of a product candidate is expensed as research and development expense as incurred. Inventory that can be used in either the production of clinical or commercial product is expensed as research and development expense when selected for use in a clinical manufacturing campaign. Inventory produced that will be used in promotional marketing campaigns is expensed to selling and marketing expense when it is selected for use in a marketing program. Inventory consisted of the following: December 31, 2019 2018 Raw materials $ 217 $ 112 Work-in-process 148 33 Finished goods 589 72 $ 954 $ 217 Restricted Cash As of December 31, 2019 and 2018, the Company held restricted cash of $1,764 and $6,614, respectively, on its consolidated balance sheet. The Company held restricted cash as security deposits for the lease of its manufacturing space and corporate headquarters. As of December 31, 2018, the Company held restricted cash as security deposits for the lease of its manufacturing space and its former corporate headquarters and a financial covenant associated with the terms of its existing debt with lenders for total indebtedness of $25,000, which restricted the Company's withdrawal or usage of $5,000. On August 2, 2019, the Company entered into a second amendment to the Credit Agreement (Note 9) in which the lenders agreed to remove the financial covenant requiring the Company to maintain a minimum of $5,000 of cash on hand . The Company’s statements of cash flows include restricted cash with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on such statements. A reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows: December 31, December 31, December 31, 2019 2018 2017 Cash and cash equivalents $ $ $ Restricted cash Total cash, cash equivalents and restricted cash as shown on the statements of cash flows $ $ $ Concentration of Credit Risk and of Significant Suppliers and Customers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents. The Company has all cash and cash equivalents balances at one accredited financial institution, in amounts that exceed federally insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company is dependent on a small number of third-party manufacturers to supply products for research and development activities in its preclinical and clinical programs and for sales of its products. The Company’s development programs as well as revenue from future sales of its product sales could be adversely affected by a significant interruption in the supply of any of the components of these products. For the year ended December 31, 2019, two individual customers accounted for 27% and 11% of the Company’s total revenue and three customers accounted for 39%, 18% and 11% of the Company’s total accounts receivable. No other customer accounted for more than 10% of total revenue or accounts receivable for the year ended December 31, 2019. Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: · Level 1—Quoted prices in active markets for identical assets or liabilities. · Level 2—Observable inputs (other than Level 1 quoted prices) such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. · Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents at December 31, 2019 and 2018, were carried at fair value determined according to the fair value hierarchy described above (Note 3). The Company’s derivative liability at December 31, 2019 was carried at fair value determined according to the fair value hierarchy described above and classified as a Level 3 measurement. The carrying value of accounts receivable, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair value due to the short-term nature of these assets and liabilities. The carrying value of the Company’s variable interest rate notes payable (Note 9) are recorded at amortized costs, which approximates fair value due to their short-term nature. On March 1, 2019, the Company issued $37,500 aggregate principal amount of unsecured senior subordinated convertible notes (the “2026 Convertible Notes”) (Note 5) and is carried, net of derivative liability, at its amortized cost of $24,305 at December 31, 2019. The estimated fair value of the 2026 Convertible Notes was $36,849 at December 31, 2019. The fair value of the 2026 Convertible Notes was estimated utilizing a binomial lattice model which requires the use of Level 3 unobservable inputs. The main input when determining the fair value for disclosure purposes is the bond yield which is updated each period to reflect the yield of a comparable instrument issued as of the valuation date. The estimated fair value presented is not necessarily indicative of an amount that could be realized in a current market exchange. The use of alternative inputs and estimation methodologies could have a material effect on these estimates of fair value. Derivative Liability The 2026 Convertible Notes allow the holders to convert all or part of the outstanding principal of their 2026 Convertible Notes into shares of the Company’s common stock provided that no conversion results in a holder beneficially owning more than 19.99% of the issued and outstanding common stock of the Company. The entire embedded conversion option is required to be separated from the 2026 Convertible Notes and accounted for as a freestanding derivative instrument subject to derivative accounting. Therefore, the entire conversion option is bifurcated from the underlying debt instrument and accounted for and valued separately from the host instrument. The Company measures the value of the embedded conversion option at its estimated fair value and recognizes changes in the estimated fair value in other income (expense), net in the consolidated statements of operations and comprehensive loss during the period of change. The embedded conversion is recognized as a derivative liability in the Company’s consolidated balance sheet. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over a three- to five-year estimated useful life. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the related asset. Expenditures for repairs and maintenance of assets are charged to expense as incurred. Upon retirement or sale, the cost and related accumulated depreciation of assets disposed of are removed from the accounts and any resulting gain or loss is included in loss from operations. Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends, and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value, determined based on discounted cash flows. The Company has had no impairment triggers of long-lived assets. Research and Development Costs Research and development costs are expensed as incurred. Included in research and development expenses are salaries, stock-based compensation and benefits of employees and other operational costs related to the Company’s research and development activities, including external costs of outside vendors engaged to conduct preclinical studies and clinical trials, manufacturing costs of the Company’s products prior to regulatory approval, costs related to collaboration agreements and facility-related expenses. Research Contract Costs and Accruals The Company has entered into various research and development contracts with research institutions and other companies both inside and outside of the United States. Certain of these agreements have cancellation clauses, and related payments are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs. Judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs. Patent Costs All patent-related costs incurred in connection with filing and prosecuting patent applications are recorded as general and administrative expenses as incurred, as recoverability of such expenditures is uncertain. Accounting for Stock-Based Compensation The Company measures all stock options and other stock-based awards granted to employees and directors at the fair value on the date of the grant using the Black-Scholes option-pricing model. The fair value of the awards is recognized as expense, net of estimated forfeitures, over the requisite service period, which is generally the vesting period of the respective award. The straight-line method of expense recognition is applied to all awards with service-only conditions. Following the Company’s adoption of ASU 2018-07, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”), on January 1, 2019, for stock-based awards issued to non-employees, the Company no longer revalues non-employee awards at each reporting date and instead calculates the fair value of the awards as of the grant date using the Black-Scholes option-pricing model. Compensation expense for these awards is recognized over the related service period. The Company classifies stock-based compensation expense in its consolidated statement of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified. The Company recognizes compensation expense for only the portion of awards that are expected to vest. In developing a forfeiture rate estimate, the Company has considered its historical experience to estimate pre-vesting forfeitures for service-based awards. The impact of a forfeiture rate adjustment will be recognized in full in the period of adjustment, and if the actual forfeiture rate is materially different from the Company’s estimate, the Company may be required to record adjustments to stock-based compensation expense in future periods. Income Taxes The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in the Company’s tax returns. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties. Segment Data The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company’s singular focus is on advancing its bioresorbable hydrogel product candidates for the programed-release delivery of therapeutic agents, specifically for ophthalmology. All tangible assets are held in the United States. Revenue to date has been generated through product sales, all of which has been earned in the United States. Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2019 and 2018, there were no items that gave rise to other comprehensive loss and therefore, there was no difference between net loss and comprehensive loss. For the year ended December 31, 2017, other comprehensive loss consisted of unrealized gains from marketable securities. Net Loss Per Share The Company follows the two-class method when computing net loss per share as the Company has issued shares that meet the definition of participating securities. The two-class method determines net loss per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based on their respective rights to receive dividends as if all income for the period had been distributed. Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period. Diluted net loss attributable to common stockholders is computed by adjusting net loss attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities, including the assumed conversion of the Company’s 2026 Convertible Notes, outstanding stock options and common stock warrants, except where the result would be anti-dilutive. Diluted net loss per share attributable to common stockholders is computed by dividing the diluted net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of the conversion of the 2026 Convertible Notes, the exercise of outstanding stock options and common stock warrants. In the diluted net loss per share calculation, net loss would also be adjusted for the elimination of interest expense on the 2026 Convertible Notes (which includes amortization of the discount created upon bifurcation of the conversion option from the debt) and, the mark-to-market gain or loss each period to the bifurcated conversion option, if the impact was not anti-dilutive. Recently Adopted Accounting Pronouncements In February 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), a new standard issued to increase transparency and comparability among organizations related to their leasing activities. This standard established a right-of-use model that requires all lessees to recognize right-of-use assets and lease liabilities on their balance sheet that arise from leases as well as provide disclosures with respect to certain qualitative and quantitative information related to a company's leasing arrangements to meet the objective of allowing users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. The FASB subsequently issued the following amendments to ASU 2016-02 that have the same effective date and transition date: ASU No. 201

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	12 Months Ended
	Dec. 31, 2019
Fair Value of Financial Assets and Liabilities
Fair Value of Financial Assets and Liabilities	3. Fair Value of Financial Assets and Liabilities The following tables present information about the Company’s financial assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2019 and 2018 and indicate the level of the fair value hierarchy utilized to determine such fair value: Fair Value Measurements as of December 31, 2019 Using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ $ 45,156 $ — $ 45,156 Liability: Derivative liability (Note 4) — — 12,124 12,124 Total $ — $ 45,156 $ 12,124 $ 57,280 Fair Value Measurements as of December 31, 2018 Using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ — $ 50,906 $ — $ 50,906 Total $ — $ 50,906 $ — $ 50,906 During the year ended December 31, 2019 and 2018, there were no transfers between Level 1, Level 2 and Level 3.

Derivative Liability

Derivative Liability	12 Months Ended
	Dec. 31, 2019
Derivative Liability
Derivative Liability	4. Derivative Liability The 2026 Convertible Notes (Note 5) contained an embedded conversion option that met the criteria to be bifurcated and accounted for separately from the 2026 Convertible Notes (the "Derivative Liability"). The Derivative Liability was recorded at fair value upon the issuance of the 2026 Convertible Notes and is subsequently remeasured to fair value at each reporting period. The Derivative Liability was initially valued and remeasured using a "with-and-without" method. The "with-and-without" methodology involves valuing the whole instrument on an as-is basis and then valuing the instrument without the embedded conversion option. The difference between the entire instrument with the embedded conversion option compared to the instrument without the embedded conversion option is the fair value of the derivative, recorded as the Derivative Liability. The fair value of the 2026 Convertible Notes with and without the conversion option is estimated using a binomial lattice approach. The main inputs to valuing the 2026 Convertible Notes with the conversion option as of December 31, 2019 include the Company’s stock price on the valuation date ($3.95 on December 31, 2019), the expected annual volatility of the Company’s stock (86%) and the bond yield (13.0%), which was derived by making the fair value of the 2026 Convertible Notes equal to the face value on the issuance date. Fair value measurements are highly sensitive to changes in these inputs and significant changes in these inputs would result in a significantly higher or lower fair value. A roll forward of the derivative liability is as follows: As of December 31, 2019 Balance at December 31, 2018 $ — Initial value 16,434 Change in fair value (4,310) Balance at December 31, 2019 $ 12,124

Convertible Notes

Convertible Notes	12 Months Ended
	Dec. 31, 2019
Convertible Notes
Convertible Notes	5. Convertible Notes On March 1, 2019, the Company issued $37,500 of 2026 Convertible Notes. Each 2026 Convertible Note accrues interest at an annual rate of 6% of its outstanding principal amount, which is payable, along with the principal amount at maturity, on March 1, 2026, unless earlier converted, repurchased or redeemed. The Company includes the deferred interest in the balance of the 2026 Convertible Notes on its consolidated balance sheet. The effective annual interest rate for the 2026 Convertible Notes was 14.8% through December 31, 2019. The holders of the 2026 Convertible Notes may convert all or part of the outstanding principal amount of their 2026 Convertible Notes into shares of the Company’s common stock, par value $0.0001 per share, prior to maturity and provided that no conversion results in a holder beneficially owning more than 19.99% of the issued and outstanding common stock of the Company. The conversion rate is initially 153.8462 shares of the Company’s common stock per $1,000 principal amount of the 2026 Convertible Notes, which is equivalent to an initial conversion price of $6.50 per share. The conversion rate is subject to adjustment in customary circumstances such as stock splits or similar changes to the Company’s capitalization. At its election, the Company may choose to make such conversion payment in cash, in shares of common stock, or a combination thereof. Upon any conversion of any 2026 Convertible Note, the Company is obligated to make a cash payment to the holder of such 2026 Convertible Note for any interest accrued but unpaid on the principal amount converted. Upon the occurrence of a Corporate Transaction (as defined below), each holder has the option to require the Company to repurchase all or part of the outstanding principal amount of such note at a repurchase price equal to 100% of the outstanding principal amount of the 2026 Convertible Note to be repurchased, plus accrued and unpaid interest to, but excluding the repurchase date. In addition, each holder is entitled to receive an additional make-whole cash payment in accordance with a table set forth in each 2026 Convertible Note. Upon conversion by the holder, the Company has the right to select the settlement of the conversion in either shares of common stock, cash, or in a combination thereof. In addition, the Company is obligated to make a cash payment to the holder of such 2026 Convertible Note for any interest accrued but unpaid on the principal amount converted. · If the Company elects to satisfy such conversion by shares of common stock, the Company shall deliver to the converting holder in respect of each $1,000 principal amount of 2026 Convertible Notes being converted a number of common shares equal to the conversion rate in effect on the conversion date; · If the Company elects to satisfy such conversion by cash settlement, the Company shall pay to the converting holder in respect of each $1,000 principal amount of 2026 Convertible Notes being converted cash in an amount equal to the sum of the Daily Conversion Values (as defined below) for each of the twenty (20) consecutive trading days during a specified period. The “Daily Conversion Values” is defined as each of the 20 consecutive trading days during the specified period, 5.0% of the product of (a) the conversion rate on such trading day and (b) the Daily VWAP on such trading day. The Daily VWAP is defined as each of the 20 consecutive trading days during the applicable Observation Period, the per share volume-weighted average price as displayed under the heading “Bloomberg VWAP” on the Bloomberg page for the Company. · If the Company elects to satisfy such conversion by combination, the Company shall pay or deliver, as the case may be, in respect of each $1,000 principal amount of 2026 Convertible Notes being converted, a settlement amount equal to the sum of the Daily Settlement Amounts (as defined below) for each of the twenty (20) consecutive trading days during the specified period. The “Daily Settlement Amount” is defined as, for each of the 20 consecutive trading days during the specified period: (a) cash in an amount equal to the lesser of (i) the Daily Measurement Value (as defined below) and (ii) the Daily Conversion Value on such Trading Day; and (b) if the Daily Conversion Value on such trading day exceeds the Daily Measurement Value, a number of Shares equal to (i) the difference between the Daily Conversion Value and the Daily Measurement Value, divided by (ii) the Daily VWAP for such Trading Day. The “Daily Measurement Value” is defined as the Specified Dollar Amount (as defined below), if any, divided by 20. The “Specified Dollar Amount” is defined as the maximum cash amount per $1,000 principal amount of Notes to be received upon conversion as specified in the notice specifying the Company’s chosen settlement method. In the event of a Corporate Transaction, the noteholder shall have the right to either (a) convert all of the unpaid principal at the conversion rate and receive a cash payment equal to (i) the outstanding accrued but unpaid interest under the 2026 Convertible Note to, but excluding, the corporate transaction conversion date (to the extent such date occurs prior to March 1, 2026, the maturity date of the 2026 Convertible Notes) plus (ii) and an additional amount of consideration based on a sliding scale depending on the date of such as Corporate transaction or (b) require the Company to repurchase all or part of the outstanding principal amount of such 2026 Convertible Note at a repurchase price equal to 100% of the outstanding principal amount of the 2026 Convertible Note to be repurchased, plus accrued and unpaid interest to, but excluding, the repurchase date. A corporate transaction includes (i) a merger or consolidation executed through a tender offer or change of control (other than one in which stockholders of the Company own a majority by voting power of the outstanding shares of the surviving or acquiring corporation); (ii) a sale, lease, transfer, of all or substantially all of the assets of the Company; or (iii) if the Company’s common stock ceases to be listed or quoted on any of the New York Stock Exchange, the Nasdaq Global Select Market, the Nasdaq Global Market or the Nasdaq Capital Market (the “Corporate Transaction”). On or after March 1, 2022, if the last reported sale price of the common stock has been at least 130% of the conversion rate then in effect for 20 of the preceding 30 trading days (including the last trading day of such period), the Company is entitled, at its option, to redeem all or part of the outstanding principal amount of the 2026 Convertible Notes, on a pro rata basis, at an optional redemption price equal to 100% of the outstanding principal amount of the 2026 Convertible Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the optional redemption date. The 2026 Convertible Notes are subject to acceleration upon the occurrence of specified events of default, including a default or breach of certain contracts material to the Company and the delisting and deregistration of the Company’s common stock. As discussed in Note 4, the Company determined that the embedded conversion option is required to be separated from the 2026 Convertible Notes and accounted for as a freestanding derivative instrument subject to derivative accounting. The allocation of proceeds to the conversion option results in a discount on the 2026 Convertible Notes. The Company is amortizing the discount to interest expense over the term of the 2026 Convertible Notes using the effective interest method. A summary of the 2026 Convertible Notes at December 31, 2019 is as follows: December 31, 2019 2026 Convertible Notes $ 37,500 Less: unamortized discount (15,101) 22,399 Accrued interest 1,906 Total $ 24,305

Property and Equipment, net

Property and Equipment, net	12 Months Ended
	Dec. 31, 2019
Property and Equipment, net
Property and Equipment, net	6. Property and Equipment, net Property and equipment, net consisted of the following: December 31, 2019 2018 Equipment $ 9,511 $ 7,917 Leasehold improvements 9,074 8,675 Furniture and fixtures 1,132 760 Software 214 180 Construction in progress 239 331 20,170 17,863 Less: Accumulated depreciation and amortization (10,019) (7,627) $ 10,151 $ 10,236 Depreciation and amortization expense was $2,530, $2,286 and $1,625 for the years ended December 31, 2019, 2018 and 2017, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2019
Accrued Expenses
Accrued Expenses	7. Accrued Expenses Accrued expenses consisted of the following: December 31, December 31, 2019 2018 Accrued payroll and related expenses $ 5,042 $ 3,558 Accrued rent — 267 Accrued professional fees 1,011 1,393 Accrued research and development expenses 849 380 Accrued other 733 596 $ 7,635 $ 6,194

Collaboration Agreement

Collaboration Agreement	12 Months Ended
	Dec. 31, 2019
Collaboration Agreement
Collaboration Agreement	8. Collaboration Agreement On October 10, 2016, the Company entered into a Collaboration, Option and License Agreement (the “Collaboration Agreement”) with Regeneron Pharmaceuticals, Inc. (“Regeneron”) for the development and potential commercialization of products using the Company’s hydrogel in combination with Regeneron’s large molecule VEGF-targeting compounds for the treatment of retinal diseases. The Collaboration Agreement does not cover the development of any product candidates that deliver small molecule drugs, including TKIs for any target including VEGF, or any product candidate that delivers large molecule drugs other than those that target VEGF proteins. Under the terms of the Collaboration Agreement, the Company and Regeneron have agreed to conduct a joint research program with the aim of developing a sustained-release formulation of aflibercept, currently marketed under the tradename Eylea, that is suitable for advancement into clinical development. The Company has granted Regeneron an option (the “Option”) to enter into an exclusive, worldwide license to develop and commercialize products using the Company’s hydrogel in combination with Regeneron’s large molecule VEGF-targeting compounds (“Licensed Products”). Under the term of the Collaboration Agreement, Regeneron is responsible for funding an initial preclinical tolerability study. If Regeneron decided to exercise the Option, Regeneron will conduct further preclinical development and an initial clinical trial under a collaboration plan. The Company is obligated to reimburse Regeneron for certain development costs incurred by Regeneron under the collaboration plan during the period through the completion of the initial clinical trial, subject to a cap of $25,000, which cap may be increased by up to $5,000 under certain circumstances. If Regeneron elects to proceed with further development following the completion of the collaboration plan, it will be solely responsible for conducting and funding further development and commercialization of product candidates. If the Option is exercised, Regeneron is required to use commercially reasonable efforts to research, develop and commercialize at least one Licensed Product. Such efforts shall include initiating the dosing phase of a subsequent clinical trial within specified time periods following the completion of the first-in-human clinical trial or the initiation of preclinical toxicology studies, subject to certain extensions. Under the terms of the Collaboration Agreement, Regeneron has agreed to pay the Company $10,000 upon the exercise of the Option. The Company is also eligible to receive up to $145,000 per Licensed Product upon the achievement of specified development and regulatory milestones, $100,000 per Licensed Product upon first commercial sale of such Licensed Product and up to $50,000 based on the achievement of specified sales milestones for all Licensed Products. In addition, the Company is entitled to tiered, escalating royalties, in a range from a high-single digit to a low-to-mid teen percentage of net sales of Licensed Products. In December 2017, the Company delivered to Regeneron a proposed final formulation for the initial preclinical tolerability study. Regeneron initiated the preclinical study in early 2018. The Company and Regeneron have subsequently reached an understanding that the proposed formulation was not final and have ceased development of it. The Company is currently in discussions with Regeneron, in accordance with the terms of the Collaboration Agreement, regarding the development of an alternative formulation.

Notes Payable

Notes Payable	12 Months Ended
	Dec. 31, 2019
Notes Payable
Notes payable	9. Notes Payable The Company entered into a credit and security agreement in 2014 (as amended to date, the “Credit Agreement”) establishing the Company’s credit facility (the “Credit Facility”). The Company has a total borrowing capacity of $25,000 under the Credit Facility, which has been fully drawn down as of December 31, 2019. In December 2018, the Company amended the terms of the Credit Agreement to increase total indebtedness under the Credit Facility to $25,000 which was used primarily to pay-off outstanding balances as of the closing date. The Company is required to make interest-only payments under the Credit Facility until December 2020. Commencing in January 2021, the Company is required to make 36 equal monthly installments of principal in the amount of $694, plus interest, through December 2023. In the event the Company achieves certain milestones under the Credit Agreement, the Company has the right to extend the interest-only payments through December 21, 2021 and make 24 equal monthly installments of principal in the amount of $1,042, plus interest. The Company has not assumed the achievement of these milestones for purposes of disclosures herein. Amounts borrowed under the Credit Agreement are at LIBOR base rate, subject to 2.00% floor, plus 7.25%. The interest rate on the date of the amendment was 9.76%. In addition, a final payment (exit fee) equal to 3.5% of amounts drawn under the Credit Facility, or $875 based on borrowings of $25,000, is due upon the maturity date of December 21, 2023. The Company is accruing the exit fee through December 21, 2023. On August 2, 2019, the Company entered into a second amendment to the Credit Agreement in which the lenders agreed to remove the financial covenant requiring the Company to maintain a minimum of $5,000 of cash on hand. Prior to this amendment, the Company was required to maintain a minimum of $5,000 of cash on hand as a financial covenant to the borrowing arrangement, which the Company had included in long-term restricted cash. There are no other financial covenants associated with the Credit Agreement. However, there are negative covenants restricting the Company’s activities, including limitations on dispositions, mergers or acquisitions; encumbering its intellectual property; incurring indebtedness or liens; paying dividends; making certain investments; and engaging in certain other business transactions. The Company is not in violation of any of the covenants. The obligations under the Credit Agreement are subject to acceleration upon the occurrence of specified events of default, including a material adverse change in the Company’s business, operations or financial or other condition. The debt is collateralized by substantially all of the Company’s assets, including its intellectual property. In accordance with the Credit Agreement, in connection with the Company’s desire to issue and sell the 2026 Convertible Notes, the Company amended the terms of its debt with existing lenders in February 2019. The amendment added to the Credit Agreement, among other provisions, a negative covenant restricting the Company from paying the holders of the 2026 Convertible Notes ahead in priority to the existing lenders, for so long as indebtedness remains outstanding under the Credit Facility, and a cross-default provision to establish that an event of default under the purchase agreement for the 2026 Convertible Notes also constitutes an event of default under the Credit Agreement. Borrowings outstanding are as follows : December 31, December 31, 2019 2018 Borrowings outstanding $ 25,000 $ 25,000 Accrued exit fee 180 5 Unamortized discount $ 25,007 $ 24,788 As of December 31, 2019, the annual repayment requirements for the Credit Facility, inclusive of interest and the final payment of $875 due at expiration, were as follows: Interest and Year Ending December 31, Principal Final Payment Total 2020 — 2,481 2,481 2021 8,333 2,094 10,427 2022 8,333 1,269 9,602 2023 8,334 1,320 9,654 $ 25,000 $ 7,164 $ 32,164

Warrants

Warrants	12 Months Ended
	Dec. 31, 2019
Warrants
Warrants	10. Warrants The Company has warrants for the purchase of 18,939 shares of common stock outstanding at December 31, 2019 at a weighted average exercise price of $7.92 per share and an expiration date of April 17, 2021.

Preferred Stock

Preferred Stock	12 Months Ended
	Dec. 31, 2019
Preferred Stock
Preferred Stock	11. Preferred Stock The Amended and Restated Certificate of Incorporation authorized 5,000,000 shares of preferred stock, $0.0001 par value, all of which is undesignated and none of which are issued or outstanding at December 31, 2019.

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2019
Common Stock
Common Stock	12. Common Stock The Amended and Restated Certificate of Incorporation authorized 100,000,000 shares of the Company’s common stock. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. On April 5, 2019, the Company entered into an Open Market Sales Agreement SM (the “2019 Sales Agreement”) with Jefferies, LLC (“Jefferies”), under which the Company may offer and sell its common stock having aggregate proceeds of up to $50,000 from time-to-time through Jefferies, acting as agent. In the twelve months ended December 31, 2019, the Company sold 7,337,459 shares of common stock under the 2019 Sales Agreement, resulting in net proceeds of approximately $32,626, respectively, after commissions and expenses. In January 2018, the Company completed a follow-on offering of its common stock at a public offering price of $5.00 per share. The offering consisted of 7,475,000 shares of common stock sold by the Company, including those shares sold in connection with the exercise by the underwriter of its option to purchase additional shares. The Company received net proceeds from the follow-on offering of $34,704 after commissions and expenses. In November 2016, the Company entered into a controlled equity offering sales agreement, (the “2016 Sales Agreement”) with Cantor Fitzgerald & Co., (“Cantor”), under which the Company may offer and sell its common stock having aggregate proceeds of up to $40,000 may be sold from time to time. During the year ended December 31, 2018, the Company sold 4,121,173 shares of common stock under the 2016 Sales Agreement, resulting in net proceeds of approximately $26,824 after underwriting discounts, commissions and expenses. Through December 31, 2018, the Company had sold 5,011,741 shares of common stock under the 2016 Sales Agreement, resulting in net proceeds of approximately $33,427 after underwriting discounts, commissions and expenses. In the three months ended March 31, 2019, the Company sold 1,318,481 shares of common stock under the 2016 Sales Agreement, resulting in net proceeds of approximately $4,954 after underwriting discounts and commissions and expenses. Through March 31, 2019, the Company sold 6,330,222 shares of common stock under the 2016 Sales Agreement, resulting in net proceeds of approximately $38,381 after underwriting discounts and commissions and expenses. As of February 25, 2019, the Company had no amounts remaining available for future sale under the 2016 Sales Agreement. On February 28, 2019, pursuant to the 2016 Sales Agreement, the Company delivered a termination notice to Cantor, terminating the 2016 Sales Agreement. As of December 31, 2019, the Company had reserved 9,499,615 shares of common stock for the exercise of outstanding stock options and the number of shares remaining available for grant under the Company’s 2014 Stock Incentive Plan (the “2014 Plan”) and the 2019 Inducement Stock Incentive Plan (the “2019 Inducement Plan”), the number of shares available for issuance under the 2014 Employee Stock Purchase Plan (Note 13), and the outstanding warrants to purchase common stock (Note 10).

Stock-Based Awards

Stock-Based Awards	12 Months Ended
	Dec. 31, 2019
Stock-Based Awards
Stock-Based Awards	13. Stock-Based Awards 2014 Stock Incentive Plan The 2014 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock-based awards. The number of shares initially reserved for issuance under the 2014 Plan was 1,336,907 shares of common stock, which was increased to 2,126,907 on January 1, 2015. The number of shares reserved for issuance may be increased by the number of shares under the 2006 Stock Option Plan (the “2006 Plan”) that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company. The number of shares of common stock that may be issued under the 2014 Plan is subject to increase on the first day of each fiscal year, beginning on January 1, 2015 and ending on December 31, 2024, equal to the least of 1,659,218 shares of the Company’s common stock, 4% of the number of shares of the Company’s common stock outstanding on the first day of the applicable fiscal year, and an amount determined by the Company’s board of directors. On January 1, 2019, the number of shares available for issuance under the 2014 Plan increased by 1,659,218. As of December 31, 2019, 636,292 shares remained available for issuance under the 2014 Plan. As required by the 2006 Plan and 2014 Plan, the exercise price for stock options granted is not to be less than the fair value of common shares as of the date of grant. Inducement Stock Option Awards On June 20, 2017, the Company issued to Antony Mattessich, who became a director of the Company on June 20, 2017 and the Company’s President and Chief Executive Officer on July 26, 2017, a non-statutory stock option to purchase an aggregate of 590,000 shares of the Company’s common stock at an exercise price of $10.94 per share. Subject to Mr. Mattessich’s continued service to the Company, the stock option will vest over a four-year period, with 25% of the shares underlying the option award vesting on the one year anniversary of the grant date and the remaining 75% of the shares underlying the award vesting monthly thereafter. The stock option was issued outside of the Company’s 2014 Plan as an inducement material to Mr. Mattessich’s acceptance of entering into employment with the Company in accordance with Nasdaq Listing Rule 5635(c)(4). On July 9, 2019, the Company issued to the Senior Vice President, Head of Business Development, a non-statutory stock option to purchase an aggregate of 60,000 shares of our common stock at an exercise price of $5.13 per share. Subject to Senior Vice President, Head of Business Development continued service to the Company, the stock option will vest over a four-year period, with 25% of the shares underlying the option award vesting on the one-year anniversary of the grant date and the remaining 75% of the shares underlying the award vesting monthly thereafter. The stock option was issued outside of the Company’s 2014 Plan as an inducement material to Senior Vice President, Head of Business Development’s acceptance of entering into employment with us in accordance with Nasdaq Listing Rule 5635(c)(4). On October 29, 2019, the 2019 Inducement Plan was approved by the Board of Directors of the Company. Awards under the Plan may only be granted to persons who (a) were not previously an employee or director of the Company or (b) are commencing employment with the Company following a bona fide period of non-employment, in either case as an inducement material to the individual’s entering into employment with the Company and in accordance with the requirements of Nasdaq Stock Market Rule 5635(c)(4). For the avoidance of doubt, neither consultants nor advisors shall be eligible to participate in the Plan. Each person who is granted an Award under the 2019 Inducement Plan is deemed a “Participant.” The Plan provides for the following types of awards, each of which is referred to as an “Award”: non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards. The number of shares of common stock that may be issued under the 2019 Plan is 500,000. As of December 31, 2019, 446,000 shares remained available for issuance under the 2019 Inducement Plan. 2014 Employee Stock Purchase Plan The Company’s has a 2014 Employee Stock Purchase Plan (the “ESPP”) with a total of 207,402 shares of common stock reserved for issuance under this plan which increased to 232,402 shares of common stock on January 1, 2015. The number of shares of common stock that may be issued under the ESPP will automatically increase on the first day of each fiscal year, commencing on January 1, 2015 and ending on December 31, 2024, in an amount equal to the least of 207,402 shares of the Company’s common stock, 0.5% of the number of shares of the Company’s common stock outstanding on the first day of the applicable fiscal year, and an amount determined by the Company’s board of directors. On January 1, 2019, the number of shares available for issuance under the 2014 Plan increased by 207,402. As of December 31, 2019, 477,967 shares of common stock remained available for issuance. Stock Option Valuation The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. The Company estimates its expected volatility using a weighted average of the historical volatility of its publicly traded peer companies and the volatility of its common stock, and expect to continue to do so until such time as the Company has adequate historical data regarding the volatility of its traded stock price. The expected term of the Company’s stock options to employees has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The expected term of stock options granted to nonemployees is equal to the contractual term of the option award. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. As of December 31, 2019, there were no outstanding unvested service-based stock options held by nonemployees. The assumptions that the Company used to determine the fair value of the stock options granted to employees and directors are as follows, presented on a weighted average basis: Year Ended December 31, 2019 2018 2017 Risk-free interest rate 2.25 % 2.65 % 2.00 % Expected term (in years) 6 6 6 Expected volatility % 102 % 102 % Expected dividend yield — % — % — % The following table summarizes the Company’s stock option activity: Weighted Weighted Average Average Remaining Aggregate Shares Issuable Exercise Contractual Intrinsic Under Options Price Term Value (In years) Outstanding as of December 31, 2018 5,230,831 $ 8.67 7.5 $ 654 Granted 3,985,025 4.06 Exercised (28,583) 2.72 Forfeited (1,266,856) 6.84 Outstanding as of December 31, 2019 7,920,417 $ 6.67 7.6 $ 704 Options vested and expected to vest as of December 31, 2019 7,065,332 $ 6.96 7.3 $ — Options exercisable as of December 31, 2019 3,790,742 $ 8.67 6.0 $ 651 The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The aggregate intrinsic value of stock options exercised was $54, $551 and $408 during the years ended December 31, 2019, 2018 and 2017 respectively. The weighted average grant date fair value of stock options granted to employees and directors during the years ended December 31, 2019, 2018, 2017 was $2.99, $4.48 and $6.44 per share, respectively. Stock-based Compensation The Company recorded stock-based compensation expense related to stock options in the following expense categories of its statements of operations: Year Ended December 31, 2019 2018 2017 Research and development $ 2,312 $ 2,557 $ 2,584 Selling and marketing 1,013 449 633 General and administrative 5,434 4,477 4,104 $ 8,759 $ 7,483 $ 7,321 As of December 31, 2019, the Company had an aggregate of $10,566 of unrecognized stock-based compensation cost, which is expected to be recognized over a weighted average period of 2.5 years.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2019
Net Loss Per Share
Net Loss Per Share	14. Net Loss Per Share Basic and diluted net loss per share attributable to common stockholders was calculated as follows for the years ended December 31, 2019, 2018 and 2017: Year Ended December 31, 2019 2018 2017 Numerator: Net loss attributable to common stockholders $ (86,372) $ (59,978) $ (63,386) Denominator: Weighted average common shares outstanding, basic and diluted 45,273,231 38,115,142 28,818,196 Net loss per share attributable to common stockholders, basic and diluted $ (1.91) $ (1.57) (2.20) The Company excluded the following common stock equivalents, outstanding as of December 31, 2019, 2018, and 2017, from the computation of diluted net loss per share attributable to common stockholders for the years ended December 31, 2019, 2018 and 2017 because they had an anti-dilutive impact due to the net loss incurred for the periods. The Company also excluded the shares issuable upon conversion of the 2026 Convertible notes from the computation of diluted net loss per share for the year ended December 31, 2019 because they had an anti-dilutive impact. December 31, 2019 2018 2017 Options to purchase common stock 7,920,417 5,230,831 4,002,374 Shares issuable upon conversion of 2026 Convertible Notes, if converted 5,769,232 — — Warrants for the purchase of common stock 18,939 18,939 18,939 13,708,588 5,249,770 4,021,313

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies.
Commitments and Contingencies	15. Commitments and Contingencies Intellectual Property Licenses The Company has a license agreement with Incept, LLC (“Incept”) (Note 19) to use and develop certain patent rights (the “Incept License”). Under the Incept License, as amended and restated, the Company was granted a worldwide, perpetual, exclusive license to develop and commercialize products that are delivered to or around the human eye for diagnostic, therapeutic or prophylactic purposes relating to ophthalmic diseases or conditions. The Company is obligated to pay low single-digit royalties on net sales of commercial products developed using the licensed technology, commencing with the date of the first commercial sale of such products and until the expiration of the last to expire of the patents covered by the license. Any of the Company’s sublicensees also will be obligated to pay Incept a royalty equal to a low single-digit percentage of net sales made by it and will be bound by the terms of the agreement to the same extent as the Company. The Company is obligated to reimburse Incept for its share of the reasonable fees and costs incurred by Incept in connection with the prosecution of the patent applications licensed to the Company under the Incept License. Through December 31, 2019, royalties paid under this agreement related to product sales were $306 and have been charged to cost of product revenue. On September 13, 2018, (the “Effective Date) the Company entered into a second amended and restated license agreement (the “Second Amended Agreement”) with Incept. The Second Amended Agreement amends and restates in full the Company’s prior amended and restated Incept License (the “Prior Agreement” or “Original License”) to expand the scope of the Company’s intellectual property license and modify future intellectual property ownership and other rights thereunder. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners, and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and senior management team that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows, and it has not accrued any liabilities related to such obligations in its consolidated financial statements as of December 31, 2019. Purchase Commitments Purchase commitments represent non-cancelable contractual commitments associated with certain clinical trial activities within the Company’s clinical research organization. Manufacturing Commitments Manufacturing contracts generally provide for termination on notice, and therefore are cancelable contracts but are contracts that the Company is likely to continue, regardless of the fact that they are cancelable. Collaboration Agreement On October 10, 2016, the Company entered into a Collaboration Agreement with Regeneron (Note 8). If the Option to enter into an exclusive worldwide license is exercised, Regeneron will conduct further preclinical development and an initial clinical trial under a collaboration plan. The Company is obligated to reimburse Regeneron for certain development costs incurred by Regeneron under the collaboration plan during the period through the completion of the initial clinical trial, subject to a cap of $25,000, which cap may be increased by up to $5,000 under certain circumstances; the timing of such payments are not known. If Regeneron elects to proceed with further development following the completion of the collaboration plan, it will be solely responsible for conducting and funding further development and commercialization of product candidates. If the Option is exercised, Regeneron is required to use commercially reasonable efforts to research, develop and commercialize at least one Licensed Product. Such efforts shall include initiating the dosing phase of a subsequent clinical trial within specified time periods following the completion of the first-in-human clinical trial or the initiation of preclinical toxicology studies, subject to certain extensions. Through December 31, 2019, the Option has not been exercised and no payments have been made to Regeneron. Legal Proceedings Securities Class Actions On July 7, 2017, a putative class action lawsuit was filed against the Company and certain of the Company’s current and former executive officers in the United States District Court for the District of New Jersey, captioned Thomas Gallagher v. Ocular Therapeutix, Inc, et al. , Case No. 2:17-cv-05011. The complaint purports to be brought on behalf of shareholders who purchased the Company’s common stock between May 5, 2017 and July 6, 2017. The complaint generally alleges that the Company and certain of the Company’s current and former officers violated Sections 10(b) and/or 20(a) of the Securities Exchange Act of 1934 (“Exchange Act”) and Rule 10b-5 promulgated thereunder by making allegedly false and/or misleading statements concerning the Form 483 issued by the FDA related to DEXTENZA and the Company’s manufacturing operations for DEXTENZA. The complaint seeks unspecified damages, attorneys’ fees, and other costs. On July 14, 2017, an amended complaint was filed; the amended complaint purports to be brought on behalf of shareholders who purchased the Company’s common stock between May 5, 2017 and July 11, 2017, and otherwise includes allegations similar to those made in the original complaint. On July 12, 2017, a second putative class action lawsuit was filed against the Company and certain of the Company’s current and former executive officers in the United States District Court for the District of New Jersey, captioned Dylan Caraker v. Ocular Therapeutix, Inc., et al. , Case No. 2:17-cv-05095. The complaint purports to be brought on behalf of shareholders who purchased the Company’s common stock between May 5, 2017 and July 6, 2017. The complaint includes allegations similar to those made in the Gallagher complaint, and seeks similar relief. On August 3, 2017, a third putative class action lawsuit was filed against the Company and certain of the Company’s current and former executive officers in the United States District Court for the District of New Jersey, captioned Shawna Kim v. Ocular Therapeutix, Inc., et al. , Case No. 2:17-cv-05704. The complaint purports to be brought on behalf of shareholders who purchased the Company’s common stock between March 10, 2016 and July 11, 2017. The complaint includes allegations similar to those made in the Gallagher complaint, and seeks similar relief. On October 27, 2017, a magistrate judge for the United States District Court for the District of New Jersey granted the defendants’ motion to transfer the above-referenced Gallagher, Caraker, and Kim litigations to the United States District Court for the District of Massachusetts. These matters were assigned the following docket numbers in the District of Massachusetts: 1:17-cv-12288 ( Gallagher ), 1:17-cv-12146 ( Caraker ), and 1:17-cv-12286 ( Kim ). On March 9, 2018, the court consolidated the three actions and appointed co-lead plaintiffs and co-lead counsel for the consolidated action. On May 7, 2018, co-lead plaintiffs filed a consolidated amended class action complaint. The amended complaint makes allegations similar to those in the original complaints, against the same defendants, and seeks similar relief on behalf of shareholders who purchased the Company’s common stock between March 10, 2016 and July 11, 2017. The amended complaint generally alleges that defendants violated Sections 10(b) and/or 20(a) of the Exchange Act and Rule 10b-5 promulgated thereunder. On July 6, 2018, defendants filed a motion to dismiss the consolidated amended complaint. Plaintiffs filed an opposition to the motion to dismiss on September 4, 2018, and defendants filed a reply on October 4, 2018. The court held oral argument on the motion to dismiss on February 6, 2019. By order dated April 30, 2019, the court granted defendants’ motion to dismiss. On May 31, 2019, the plaintiffs filed a notice of appeal to the United States Court of Appeals for the First Circuit regarding the District Court’s opinion and order of dismissal of the Complaint. The plaintiffs/appellants filed their opening brief on the appeal on October 23, 2019. Defendants/appellees filed their response brief on November 22, 2019. Plaintiffs/appellants filed their reply brief on December 13, 2019. The First Circuit held an oral argument on the appeal on February 4, 2020, and took the matter under advisement. The Company denies any allegations of wrongdoing and intends to vigorously defend against these lawsuits. Shareholder Derivative Litigation On July 11, 2017, a purported shareholder derivative lawsuit was filed against certain of the Company’s current and former executive officers, certain current and former board members, and the Company as a nominal defendant, in the United States District Court for the District of Massachusetts, captioned Robert Corwin v. Sawhney et al. , Case No. 1:17-cv-11270. The complaint generally alleged that the individual defendants breached fiduciary duties owed to the Company by making allegedly false and/or misleading statements concerning the Form 483 related to DEXTENZA and our manufacturing operations for DEXTENZA. The complaint purported to assert claims against the individual defendants for breach of fiduciary duty, and sought to recover on behalf of the Company for any liability the Company incurs as a result of the individual defendants’ alleged misconduct. The complaint also sought contribution on behalf of the Company from all individual defendants for their alleged violations of Sections 10(b) and/or 20(a) of the Exchange Act and Rule 10b-5 promulgated thereunder. The complaint sought declaratory, equitable, and monetary relief, an unspecified amount of damages, with interest, and attorneys’ fees and costs. On September 20, 2017, counsel for the plaintiff filed a notice of voluntary dismissal, stating that the plaintiff wished to coordinate his efforts and proceed in a consolidated fashion with the plaintiff in a similar derivative suit that was pending in the Superior Court of Suffolk County of the Commonwealth of Massachusetts captioned Angel Madera v. Sawhney et al. , Case. No. 17-2273 (which is discussed in the paragraph immediately below) by filing an action in that court subsequent to the dismissal of this lawsuit. The Corwin lawsuit was dismissed without prejudice on September 21, 2017. On October 24, 2017, the plaintiff filed a new derivative complaint in Massachusetts Superior Court (Suffolk County), captioned Robert Corwin v. Sawhney et al ., Case No. 17-3425 (BLS2). The new Corwin complaint includes allegations similar to those made in the federal court complaint and asserts a derivative claim for breach of fiduciary duty against certain of our current and former officers and directors. The complaint also asserts an unjust enrichment claim against two additional defendants, SV Life Sciences Fund IV, LP and SV Life Sciences Fund IV Strategic Partners, LP. The complaint also names the Company as a nominal defendant. On July 19, 2017, a second purported shareholder derivative lawsuit was filed against certain of the Company’s current and former executive officers, all current board members, one former board member, and the Company as a nominal defendant, in the Superior Court of Suffolk County of the Commonwealth of Massachusetts, captioned Angel Madera v. Sawhney et al. , Case. No. 17-2273. The complaint included allegations similar to those made in the Corwin complaint. The complaint purported to assert derivative claims against the individual defendants for breach of fiduciary duty, unjust enrichment, abuse of control, gross mismanagement, and waste of corporate assets, and sought to recover on behalf of the Company for any liability the Company incurs as a result of the individual defendants’ alleged misconduct. The complaint sought declaratory, equitable, and monetary relief, an unspecified amount of damages, with interest, and attorneys’ fees and costs. On November 6, 2017, the court dismissed this action without prejudice due to plaintiff’s failure to complete service of process within the time permitted under applicable court rules. On December 21, 2017, the same plaintiff filed a new derivative complaint in the same court, captioned Angel Madera v. Sawhney et al. , Case. No. 17-4126 (BLS2). The new Madera complaint is premised on substantially similar allegations as the previous complaint and purports to assert derivative claims against certain current and former executive officers and board members for breach of fiduciary duty, unjust enrichment, and waste of corporate assets, and names the Company as a nominal defendant. Like the new Corwin complaint, the new Madera complaint also asserts an unjust enrichment claim against two additional defendants, SV Life Sciences Fund IV, LP and SV Life Sciences Fund IV Strategic Partners, LP. By order dated January 29, 2018, the court consolidated the state court Corwin and Madera complaints under the Corwin docket and appointed lead counsel for plaintiffs. On February 28, 2018, plaintiffs filed a consolidated amended complaint. The consolidated complaint names substantially the same defendants and is premised on substantially similar allegations as the previous Corwin and Madera complaints, asserting claims for breach of fiduciary duty against the individual defendants and unjust enrichment against the two SV entity defendants. On April 17, 2018, all defendants served a motion to dismiss the consolidated amended complaint. On June 22, 2018, plaintiffs served their opposition to the motion to dismiss and a cross-motion to stay the proceedings pending a decision on the motion to dismiss in the above-referenced securities class action in the District of Massachusetts. On July 30, 2018, the parties filed a joint motion to stay the proceedings pending a decision on the motion to dismiss in the above-referenced securities class action in the District of Massachusetts. On August 3, 2018, the court granted the motion to stay. On January 31, 2018, a third purported shareholder derivative suit was filed against certain of the Company’s current and former executive officers, certain current and former board members, and the Company as a nominal defendant, in the United States District Court for the District of Massachusetts, captioned Brian Robinson v. Sawhney et al. , Case. No. 1:18-cv-10199. The complaint includes allegations similar to those made in the Corwin and Madera complaints. The complaint does not name either SV Life Sciences Fund, IV, LP or SV Life Sciences Fund IV Strategic Partners, LP as defendants, and adds two former officers as defendants. The complaint purports to assert derivative claims against the individual defendants for breach of fiduciary duty, waste of corporate assets, and unjust enrichment, and seeks to recover on behalf of the Company for any liability the Company incurs as a result of the individual defendants’ alleged misconduct. The complaint seeks declaratory, equitable, and monetary relief, an unspecified amount of damages, with interest, and attorneys’ fees and costs. On April 30, 2018, all defendants filed a motion to dismiss or stay the complaint. Plaintiff filed his opposition on June 22, 2018. On July 26, 2018, the parties filed a joint motion to extend the deadline for defendants to file their reply brief pending the potential substitution of the named shareholder plaintiff. On August 20, 2018, the parties filed a joint stipulation and proposed order regarding plaintiff’s unopposed request to substitute a new shareholder plaintiff and the parties’ joint request that the court stay the proceedings pending a decision on the motion to dismiss in the above-referenced securities class action in the District of Massachusetts. On September 4, 2018, the court entered the requested order substituting the named plaintiff and staying the matter. On February 16, 2018, a fourth purported shareholder derivative suit was filed against certain of the Company’s current and former executive officers, certain current and former board members, and the Company as a nominal defendant, in the United States District Court for the District of Delaware, captioned Terry Kelly v. Sawhney et al. , Case. No. 1:18-cv-00277. The complaint includes allegations similar to those made in the Corwin and Madera complaints. The complaint purports to assert derivative claims against the individual defendants for breach of fiduciary duty, unjust enrichment and waste of corporate assets, and seeks to recover on behalf of the Company for any liability the Company incurs as a result of the individual defendants’ alleged misconduct. The complaint also asserts an unjust enrichment claim against SV Life Sciences Fund IV, LP and SV Life Sciences Fund IV Strategic Partners, LP. The complaint seeks declaratory, equitable, and monetary relief, an unspecified amount of damages, with interest, and attorneys’ fees and costs. On June 11, 2018, the parties filed a stipulation staying the lawsuit pending final judgment in the consolidated derivative action pending in Massachusetts state court under the Corwin docket, described above. The court entered an order staying the case on June 12, 2018. The Company denies any allegations of wrongdoing and intend to vigorously defend against these lawsuits. In addition, the Company received a subpoena from the SEC, dated December 15, 2017, requesting documents and information concerning DEXTENZA (dexamethasone insert) 0.4mg, including related communications with the FDA, investors and others. The Company received a second subpoena from the SEC on August 21, 2018, requesting documents and information concerning its participation in two investor conferences in June 2017. By letter dated May 2, 2019, the SEC notified the Company that the SEC had concluded its investigation and did not intend to recommend an enforcement action against the Company or any individuals. The Company is unable to predict the outcome of these lawsuits or proceedings at this time. Moreover, any conclusion of these matters in a manner adverse to the Company and for which it incurs substantial costs or damages not covered by our directors’ and officers’ liability insurance would have a material adverse effect on the Company’s financial condition and business. In addition, the proceedings could adversely impact the Company’s reputation and divert management’s attention and resources from other priorities, including the execution of business plans and strategies that are important to the Company’s ability to grow the Company’s business, any of which could have a material adverse effect on the Company’s business.

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases
Leases	16. Leases The Company leases real estate, including laboratory, manufacturing and office space. The Company’s leases have remaining lease terms ranging from less than 1 year to 8 years. Certain leases include one or more options to renew, exercised at the Company’s sole discretion, with renewal terms that can extend the lease term from one year to six years. All of the Company’s leases qualify as operating leases. In October 2017, the Company entered into an amendment to a lease agreement for the Company’s laboratory and manufacturing space located at 34 Crosby Drive and 36 Crosby Drive, each in Bedford, Massachusetts. The lease term commenced on June 30, 2018 and will expire on July 31, 2023. The Company has a one-time option to terminate the lease on July 31, 2021. In June 2016, the Company entered into a lease agreement for approximately 70,712 square feet of general office, research and development and manufacturing space located at 15 Crosby Drive in Bedford, Massachusetts. The lease term commenced on February 1, 2017 and will expire on July 31, 2027. The Company has the option to extend the for two additional periods of five years by delivering written notice of the exercise not earlier than fifteen months nor later than 12 months before expiration of the original term. On April 4, 2019, the Company entered into a non-cancelable lease for 30,036 square feet of space located at 24 Crosby Drive in Bedford, Massachusetts to be used for office space. The five-year lease commenced on April 18, 2019 and terminates on March 24, 2024 and does not include any lease renewal options. The following table summarizes the presentation in the Company’s consolidated balance sheet of its operating leases: December 31, Balance sheet location 2019 Assets: Operating lease assets Operating lease assets $ Liability: Current operating lease liabilities Operating lease liabilities $ Non-current operating lease liabilities Operating lease liabilities, net of current portion Total Operating lease liabilities: $ The following table summarizes the effect of lease costs in the Company’s consolidated statements of operations and comprehensive loss: For the Year Ended December 31, Statement of operations and comprehensive loss location 2019 Operating lease costs Research and development $ Selling and marketing General and administrative $ 2,215 The minimum lease payments for the next five years and thereafter are expected to be as follows: December 31, Year Ending December 31, 2019 2020 2,432 2021 2,483 2022 2,548 2023 2,357 2024 1,569 Thereafter 3,813 Total lease payments $ 15,202 Less: interest 5,171 Present value of operating lease liabilities $ 10,031 The minimum lease payments for the next five years and thereafter is expected to be as follows: As of December 31, 2019, the weighted average remaining lease term was 6.47 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 13.55%. Supplemental disclosure of cash flow information related to our operating leases included in cash flows provided by operating activities in our consolidated statements of cash flows is as follows: For the Year Ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities $ During the years ended December 31, 2019, 2018 and 2017, the Company recognized $2,226, $1,788 and $1,733 of rental expense, respectively, related to office, laboratory, and manufacturing space. ASC 840 Disclosures The future minimum lease payments under the Company’s operating leases as of December 31, 2018, were as follows: 2019 2020 2021 2022 2023 Thereafter Total Minimum lease payments $ $

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Taxes
Income Taxes	17. Income Taxes During the years ended December 31, 2019, 2018 and 2017, the Company recorded no income tax benefits for the net operating losses incurred or the research and development tax credits generated in each year, due to its uncertainty of realizing a benefit from those items. A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2019 2018 2017 Federal statutory income tax rate 21.0 % 21.0 % 34.0 % Tax reform change — — (43.0) Research and development tax credits 2.1 3.6 3.3 State taxes, net of federal benefit 2.7 4.5 3.8 Stock-based compensation (1.3) (1.3) (2.2) Other (0.5) (0.1) 0.2 Change in deferred tax asset valuation allowance (24.0) (27.7) 3.9 Effective income tax rate — % — % — % Net deferred tax assets consisted of the following: December 31, 2019 2018 Deferred tax assets: Net operating loss carryforwards $ 70,317 $ 49,699 Tax credit carryforwards 11,966 10,160 Capitalized start-up costs 695 870 Capitalized research and development expenses, net 14,521 18,418 Operating lease liabilities 2,505 — Derivative liability 3,028 — Accrued expenses and other temporary differences 6,987 5,196 Total deferred tax assets 110,019 84,343 Valuation allowance (105,062) (84,343) Net deferred tax assets 4,957 — Deferred tax liabilities: Operating lease right of use assets (1,662) — 2026 Convertible Notes (3,295) — Total deferred tax liabilities (4,957) — Net deferred tax assets $ — $ — Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2019, 2018 and 2017 related primarily to the increase in net operating loss carryforwards, capitalized research and development expenses and research and development tax credit carryforwards offset in 2017 by a decrease in a deferred tax asset resulting from the decreased federal corporate tax rate and were as follows: Year Ended December 31, 2019 2018 2017 Valuation allowance as of beginning of year $ 84,343 $ 67,726 $ 70,236 Increases recorded to income tax provision 20,719 16,617 24,773 Decreases recorded to income tax provision — — (27,283) Valuation allowance as of end of year $ 105,062 $ 84,343 $ 67,726 As of December 31, 2019, the Company had net operating loss carryforwards for federal and state income tax purposes of $274,331 and $219,375, respectively. The federal and state net operating losses generated for annual periods prior to January 1, 2018 begin to expire in 2024. The Company’s federal net operating losses generated for the years ended December 31, 2019 and 2018, which amounted to a total of $148,250, can be carried forward indefinitely. As of December 31, 2019, the Company also had available research and development tax credit carryforwards for federal and state income tax purposes of $8,211 and $4,342, respectively, which begin to expire in 2026 and 2025, respectively. Utilization of the net operating loss carryforwards and research and development tax credit carryforwards may be subject to a substantial annual limitation under Section 382 of the Internal Revenue Code of 1986 due to ownership changes that have occurred previously or that could occur in the future. These ownership changes may limit the amount of carryforwards that can be utilized annually to offset future taxable income. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50% over a three-year period. The Company has not conducted a study to assess whether a change of control has occurred or whether there have been multiple changes of control since inception due to the significant complexity and cost associated with such a study. If the Company has experienced a change of control, as defined by Section 382, at any time since inception, utilization of the net operating loss carryforwards or research and development tax credit carryforwards would be subject to an annual limitation under Section 382, which is determined by first multiplying the value of the Company’s stock at the time of the ownership change by the applicable long-term tax-exempt rate, and then could be subject to additional adjustments, as required. Any limitation may result in expiration of a portion of the net operating loss carryforwards or research and development tax credit carryforwards before utilization. Further, until a study is completed and any limitation is known, no amounts are being presented as an uncertain tax position. The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets. Management considered the Company’s cumulative net losses and concluded that it is more likely than not that the Company would not realize the benefits of the deferred tax assets. Accordingly, a full valuation allowance was established against the net deferred tax assets as of December 31, 2019 and 2018. The Company has not recorded any amounts for unrecognized tax benefits as of December 31, 2019 or 2018. The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. There are currently no pending income tax examinations. The Company’s tax years are still open under statute from December 31, 2015 to the present. Earlier years may be examined to the extent that tax credit or net operating loss carryforwards are used in future periods. The Company’s policy is to record interest and penalties related to income taxes as part of its income tax provision. As of December 31, 2019 and 2018, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company’s statements of operations and comprehensive loss.

401(k) Savings Plan

401(k) Savings Plan	12 Months Ended
	Dec. 31, 2019
401(k) Savings Plan
401(k) Savings Plan	18. 401(k) Savings Plan The Company established a defined contribution savings plan under Section 401(k) of the Internal Revenue Code. This plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. Company contributions to the plan may be made at the discretion of the board of directors. Through December 31, 2019, no contributions have been made to the plan by the Company.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2019
Related Party Transactions
Related Party Transactions	19. Related Party Transactions Since October 2017, the Company has engaged McCarter English LLP (“McCarter”) to provide legal services to the Company, including with respect to intellectual property matters. Mr. Jonathan M. Sparks, Ph.D., a partner at McCarter & English, has also served in the capacity as the Company’s in-house counsel since October 2017. The Company incurred fees for legal services rendered by McCarter of $1,119, $1,019 and $42 for the years ended December 31, 2019, 2018 and 2017, respectively. As of December 31, 2019 and 2018, there was $107 and $526 recorded in accounts payable for McCarter. As of December 31, 2019, there was $242 recorded in accrued expenses for McCarter

Restructuring and Other Costs

Restructuring and Other Costs	12 Months Ended
	Dec. 31, 2019
Restructuring and Other Costs
Restructuring and Other Costs	20. Restructuring and Other Costs 2019 Restructuring On November 6, 2019, the Board of Directors approved an operational restructuring to eliminate a portion of the Company’s workforce to reduce expenses. As part of this operational restructuring, the Company reduced headcount by approximately 22%. The Company completed the restructuring in the fourth quarter of 2019 and recorded total restructuring costs of approximately $554 in total costs and operating expenses in the consolidated statements of operations and comprehensive loss, all of which was paid. 2017 Transition Agreements and Other Costs On July 31, 2017, the Board of Directors approved a strategic restructuring to eliminate a portion of the Company’s workforce as part of an initiative to enhance operations and reduce expenses. As part of this strategic restructuring, the Company eliminated 30 positions across the organization. During the twelve months ended December 31, 2017, t he Company recorded $1,703 of restructuring-related costs in operating expenses in research and development and selling and marking, including employee severance, benefits and related costs. On July 31, 2017, the Company entered into a transition, separation and release of claims agreement (the “Ankerud Transition Agreement”), pursuant to which Eric Ankerud resigned from his role as Executive Vice President, Regulatory, Quality and Compliance of the Company, effective immediately. Mr. Ankerud continued to serve as an at-will employee of the Company in the capacity of Senior Advisor until October 31, 2017. Under the Ankerud Transition Agreement, Mr. Ankerud is entitled to separation benefits until October 31, 2018, in the form of continuation of his base salary in the same amount in effect as of October 31, 2018; the payment of monthly premiums for healthcare and/or dental coverage; and provided he continues to provide services to the Company as a consultant, the continued vesting of his outstanding stock options awards in accordance with the applicable equity plans and stock option agreements. During the twelve months ended December 31, 2017, t he Company recorded $386 of severance expense which are included in operating expenses in research and development. On October 13, 2017, the Company entered into a transition, separation and release of claims agreement (the “Fortune Transition Agreement”) with James Fortune, pursuant to which Mr. Fortune resigned from his role as Chief Operating Officer and any and all other positions he holds as an officer or employee of the Company, effective December 31, 2017 (the “Separation Date”). Pursuant to the Fortune Transition Agreement, effective as of October 13, 2017, the Employment Agreement, by and between the Company and Mr. Fortune, dated June 19, 2014, was terminated. Under the Fortune Transition Agreement, Mr. Fortune will be entitled to separation benefits in the form of (i) the continuation of his base salary for twelve months after the Separation Date in the same amount in effect as of the October 13, 2017 and (ii) the payment of monthly premiums for healthcare and/or dental coverage at the same rate that is in effect on the Separation Date until the earlier of twelve months from the Separation Date or the date Mr. Fortune becomes eligible to receive such benefits under another employer’s benefit plan. Should any annual bonus payments be made to active Company executives for the calendar year 2017, Mr. Fortune will also be eligible to receive a bonus payment in such amount, if any, he would have received had he remained employed with the Company through the date of such bonus payments. During the twelve months ended December 31, 2017, t he Company recorded $417 of severance expense which are included in operating expenses in general and administration. The following table summarizes the restructuring and other costs by category during the twelve months ended December 31, 2017: wwe Twelve Months Ended Total Research and development $ Selling and marketing General and administration $

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2019
Selected Quarterly Financial Data (Unaudited)
Selected Quarterly Financial Data (Unaudited)	21. Selected Quarterly Financial Data (Unaudited) Three Months Ended Dec. 31, Sept. 30, June 30, Mar 31, Dec. 31, Sept. 30, June 30, Mar 31, 2019 2019 2019 2019 2018 2018 2018 2018 Statements of Operations Data: Revenue 2,256 829 650 492 504 498 648 340 Loss from operations (21,401) (23,144) (21,599) (19,658) (17,283) (14,816) (13,564) (13,455) Net loss (26,017) (18,778) (24,453) (17,124) (17,399) (15,010) (13,804) (13,765) Basic net loss per common share $ (0.53) $ (0.40) $ (0.57) $ (0.41) $ (0.42) $ (0.38) $ (0.37) $ (0.40) Diluted net loss per common share $ (0.53) $ (0.45) $ (0.57) $ (0.45) $ (0.42) $ (0.38) $ (0.37) $ (0.40)

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events
Subsequent Events	22. Subsequent Events The number of shares of common stock that may be issued under the 2014 Plan is subject to increase on the first day of each fiscal year, beginning on January 1, 2015 and ending on December 31, 2024, equal to the least of 1,659,218 shares of the Company’s common stock, 4% of the number of shares of the Company’s common stock outstanding on the first day of the applicable fiscal year, and an amount determined by the Company’s board of directors. On January 1, 2020, the number of shares available for issuance under the 2014 Plan increased by 1,659,218. The number of shares of common stock that may be issued under the ESPP will automatically increase on the first day of each fiscal year, commencing on January 1, 2015 and ending on December 31, 2024, in an amount equal to the least of 207,402 shares of the Company’s common stock, 0.5% of the number of shares of the Company’s common stock outstanding on the first day of the applicable fiscal year, and an amount determined by the Company’s board of directors. On January 1, 2020, the number of shares available for issuance under the ESPP increased by 207,402. The Company sold an additional 2,229,514 shares of common stock between January 1, 2020 and February 21, 2020, under the 2019 Sales Agreement discussed in Note 12, resulting in net proceeds of approximately $10,686 after commissions and expenses.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Summary of Significant Accounting Policies
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements reflect the operations of the Company and its wholly-owned subsidiary. All intercompany accounts and transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, revenue recognition, and the fair value of derivatives. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.
Cash Equivalents	Cash Equivalents The Company considers all short-term, highly liquid investments with original maturities of ninety days or less at date of purchase to be cash equivalents. Cash equivalents, which primarily consist of money market accounts, are stated at fair value.
Revenue Recognition	Revenue Recognition The Company recognizes product revenue from DEXTENZA for the treatment of post-surgical ocular inflammation and pain, which it began selling to customers in June 2019, and ReSure Sealant. The Company has generated limited revenues from ReSure Sealant to date and does not expect significant future sales. In November 2018, the FDA approved DEXTENZA for the treatment of ocular pain following ophthalmic surgery . The Company entered into a limited number of arrangements with specialty distributors in the United States to distribute DEXTENZA. The Company recognizes revenue in accordance with Accounting Standards Codification 606 – Revenue from Contracts with Customers (“Topic 606”). Topic 606 applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance arrangements and financial instruments. Under Topic 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to be entitled to in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract, and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to arrangements that meet the definition of a contract with a customer under Topic 606, including when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. For a complete discussion of accounting for product revenue, see Product Revenue, Net (below). Product Revenue, Net — The Company derives its product revenues from the sale of DEXTENZA in the United States to customers, which includes a limited number of specialty distributors, who then subsequently resell DEXTENZA to physicians, clinics and certain medical centers or hospitals. In addition to distribution agreements with customers, the Company enters into arrangements with government payers that provide for government mandated rebates and chargebacks with respect to the purchase of DEXTENZA. The Company recognizes revenue on product sales when the customer obtains control of the Company's product, which occurs at a point in time (upon delivery to the customer). The Company has determined that the delivery of DEXTENZA to its customers constitutes a single performance obligation. There are no other promises to deliver goods or services beyond what is specified in each accepted customer order. The Company has assessed the existence of a significant financing component in the agreements with its customers. The trade payment terms with the Company’s customers do not exceed one year and therefore the Company has elected to apply the practical expedient and no amount of consideration has been allocated as a financing component. Product revenues are recorded net of applicable reserves for variable consideration, including discounts and allowances. Transaction Price, including Variable Consideration — Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration for which reserves are established. Components of variable consideration include trade discounts and allowances, product returns, government chargebacks, discounts and rebates, and other incentives, such as voluntary patient assistance, and other fee-for-service amounts that are detailed within contracts between the Company and its customers relating to the Company’s sale of DEXTENZA. These reserves, as detailed below, are based on the amounts earned, or to be claimed on the related sales, and are classified as reductions of accounts receivable (if the amount is payable to the customer) or a current liability (if the amount is payable to a party other than a customer). These estimates take into consideration a range of possible outcomes which are probability-weighted in accordance with the expected value method in Topic 606 for relevant factors such as current contractual and statutory requirements, specific known market events and trends, industry data, and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the respective underlying contracts. The amount of variable consideration which is included in the transaction price may be constrained, and is included in the net sales price, only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized under the contract will not occur in a future period. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s original estimates, the Company will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. Trade Discounts and Allowances —The Company compensates (through trade discounts and allowances) its customers for sales order management, data, and distribution services. However, the Company has determined such services received to date are not distinct from the Company’s sale of products to the customer and, therefore, these payments have been recorded as a reduction of revenue within the statement of operations and comprehensive loss through December 31, 2019, as well as a reduction to accounts receivables, net on the consolidated balance sheets. Product Returns — Consistent with industry practice, the Company generally offers customers a limited right of return for product that has been purchased from the Company in certain circumstances as further discussed below. The Company estimates the amount of its product sales that may be returned by its customers and records this estimate as a reduction of revenue in the period the related product revenue is recognized, as well as within accrued expenses and other current liabilities, in the accompanying consolidated balance sheets. The Company currently estimates product return reserves using available industry data and its own sales information, including its visibility into the inventory remaining in the distribution channel. The Company has received no returns to date and believes the returns of DEXTENZA will be minimal. The Company’s limited right of return allows for eligible returns of DEXTENZA in the following circumstances: · Shipment errors that were the result of an error by the Company; · Quantity delivered that is greater or less than the quantity ordered; · Product distributed by the Company that is damaged in transit prior to receipt by the customer; · Product from physicians, clinics, medical centers and hospitals that was not administered to the patient that is rendered non-usable due to spoilage or mishandling; · Expired product, previously purchased directly from the Company, that is returned during the period beginning six months prior to the product’s expiration date and ending twelve months after the product’s expiration date; · Product subject to a recall; and · Product that the Company, at its sole discretion, has specified to be returned. Government Chargebacks — Chargebacks for fees and discounts to qualified government healthcare providers represent the estimated obligations resulting from contractual commitments to sell products to qualified U.S. Department of Veterans Affairs hospitals and 340B entities at prices lower than the list prices charged to customers who directly purchase the product from the Company. The 340B Drug Discount Program is a U.S. federal government program created in 1992 that requires drug manufacturers to provide outpatient drugs to eligible health care organizations and covered entities at significantly reduced prices. Customers charge the Company for the difference between what they pay for the product and the statutory selling price to the qualified government entity. These reserves are established in the same period that the related revenue is recognized, resulting in a reduction of product revenue and accounts receivables, net. Chargeback amounts are generally determined at the time of resale to the qualified government healthcare provider by customers, and the Company generally issues credits for such amounts within a few weeks of the Customer’s notification to the Company of the resale. Reserves for chargebacks consist of credits that the Company expects to issue for units that remain in the distribution channel inventories at each reporting period-end that the Company expects will be sold to qualified healthcare providers, and chargebacks that customers have claimed, but for which the Company has not yet issued a credit. Government Rebates — The Company is subject to discount obligations under state Medicaid programs and Medicare. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included in accrued expenses and other current liabilities on the consolidated balance sheets. For Medicare, the Company also estimates the number of patients in the prescription drug coverage gap for whom the Company will owe an additional liability under the Medicare Part D program. For Medicaid programs, the Company estimates the portion of sales attributed to Medicaid patients and records a liability for the rebates to be paid to the respective state Medicaid programs. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimated future claims that will be made for product that has been recognized as revenue, but which remains in the distribution channel inventories at the end of each reporting period. Other Incentives — Other incentives which the Company offers include voluntary patient assistance programs, such as the co-pay assistance program, which are intended to provide financial assistance to qualified commercially-insured patients with prescription drug co-payments required by payers. The calculation of the accrual for co-pay assistance is based on an estimate of claims and the cost per claim that the Company expects to receive associated with product that has been recognized as revenue, but remains in the distribution channel inventories at the end of each reporting period. The adjustments are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included as an accrued expenses and other current liabilities on the consolidated balance sheets.
Inventory	Inventory The Company values its inventories at the lower of cost or estimated net realizable value. The Company determines the cost of its inventories, which includes amounts related to materials and manufacturing overhead, on a first-in, first-out basis. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and it writes down any excess and obsolete inventories to their estimated realizable value in the period in which the impairment is first identified. Such impairment charges, should they occur, are recorded within cost of product revenue. The determination of whether inventory costs will be realizable requires estimates by management. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required, which would be recorded as a cost of product revenue in the consolidated statements of operations and comprehensive loss. The Company capitalizes inventory costs associated with the Company’s products after regulatory approval when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Inventory acquired prior to receipt of marketing approval of a product candidate is expensed as research and development expense as incurred. Inventory that can be used in either the production of clinical or commercial product is expensed as research and development expense when selected for use in a clinical manufacturing campaign. Inventory produced that will be used in promotional marketing campaigns is expensed to selling and marketing expense when it is selected for use in a marketing program. Inventory consisted of the following: December 31, 2019 2018 Raw materials $ 217 $ 112 Work-in-process 148 33 Finished goods 589 72 $ 954 $ 217
Restricted Cash	Restricted Cash As of December 31, 2019 and 2018, the Company held restricted cash of $1,764 and $6,614, respectively, on its consolidated balance sheet. The Company held restricted cash as security deposits for the lease of its manufacturing space and corporate headquarters. As of December 31, 2018, the Company held restricted cash as security deposits for the lease of its manufacturing space and its former corporate headquarters and a financial covenant associated with the terms of its existing debt with lenders for total indebtedness of $25,000, which restricted the Company's withdrawal or usage of $5,000. On August 2, 2019, the Company entered into a second amendment to the Credit Agreement (Note 9) in which the lenders agreed to remove the financial covenant requiring the Company to maintain a minimum of $5,000 of cash on hand . The Company’s statements of cash flows include restricted cash with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on such statements. A reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows is as follows: December 31, December 31, December 31, 2019 2018 2017 Cash and cash equivalents $ $ $ Restricted cash Total cash, cash equivalents and restricted cash as shown on the statements of cash flows $ $ $
Concentration of Credit Risk and of Significant Suppliers and Customers	Concentration of Credit Risk and of Significant Suppliers and Customers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents. The Company has all cash and cash equivalents balances at one accredited financial institution, in amounts that exceed federally insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company is dependent on a small number of third-party manufacturers to supply products for research and development activities in its preclinical and clinical programs and for sales of its products. The Company’s development programs as well as revenue from future sales of its product sales could be adversely affected by a significant interruption in the supply of any of the components of these products. For the year ended December 31, 2019, two individual customers accounted for 27% and 11% of the Company’s total revenue and three customers accounted for 39%, 18% and 11% of the Company’s total accounts receivable. No other customer accounted for more than 10% of total revenue or accounts receivable for the year ended December 31, 2019.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: · Level 1—Quoted prices in active markets for identical assets or liabilities. · Level 2—Observable inputs (other than Level 1 quoted prices) such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. · Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents at December 31, 2019 and 2018, were carried at fair value determined according to the fair value hierarchy described above (Note 3). The Company’s derivative liability at December 31, 2019 was carried at fair value determined according to the fair value hierarchy described above and classified as a Level 3 measurement. The carrying value of accounts receivable, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair value due to the short-term nature of these assets and liabilities. The carrying value of the Company’s variable interest rate notes payable (Note 9) are recorded at amortized costs, which approximates fair value due to their short-term nature. On March 1, 2019, the Company issued $37,500 aggregate principal amount of unsecured senior subordinated convertible notes (the “2026 Convertible Notes”) (Note 5) and is carried, net of derivative liability, at its amortized cost of $24,305 at December 31, 2019. The estimated fair value of the 2026 Convertible Notes was $36,849 at December 31, 2019. The fair value of the 2026 Convertible Notes was estimated utilizing a binomial lattice model which requires the use of Level 3 unobservable inputs. The main input when determining the fair value for disclosure purposes is the bond yield which is updated each period to reflect the yield of a comparable instrument issued as of the valuation date. The estimated fair value presented is not necessarily indicative of an amount that could be realized in a current market exchange. The use of alternative inputs and estimation methodologies could have a material effect on these estimates of fair value.
Derivative Liability	Derivative Liability The 2026 Convertible Notes allow the holders to convert all or part of the outstanding principal of their 2026 Convertible Notes into shares of the Company’s common stock provided that no conversion results in a holder beneficially owning more than 19.99% of the issued and outstanding common stock of the Company. The entire embedded conversion option is required to be separated from the 2026 Convertible Notes and accounted for as a freestanding derivative instrument subject to derivative accounting. Therefore, the entire conversion option is bifurcated from the underlying debt instrument and accounted for and valued separately from the host instrument. The Company measures the value of the embedded conversion option at its estimated fair value and recognizes changes in the estimated fair value in other income (expense), net in the consolidated statements of operations and comprehensive loss during the period of change. The embedded conversion is recognized as a derivative liability in the Company’s consolidated balance sheet.
Property and Equipment	Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over a three- to five-year estimated useful life. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the related asset. Expenditures for repairs and maintenance of assets are charged to expense as incurred. Upon retirement or sale, the cost and related accumulated depreciation of assets disposed of are removed from the accounts and any resulting gain or loss is included in loss from operations.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends, and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value, determined based on discounted cash flows. The Company has had no impairment triggers of long-lived assets.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Included in research and development expenses are salaries, stock-based compensation and benefits of employees and other operational costs related to the Company’s research and development activities, including external costs of outside vendors engaged to conduct preclinical studies and clinical trials, manufacturing costs of the Company’s products prior to regulatory approval, costs related to collaboration agreements and facility-related expenses.
Research Contract Costs and Accruals	Research Contract Costs and Accruals The Company has entered into various research and development contracts with research institutions and other companies both inside and outside of the United States. Certain of these agreements have cancellation clauses, and related payments are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs. Judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs.
Patent Costs	Patent Costs All patent-related costs incurred in connection with filing and prosecuting patent applications are recorded as general and administrative expenses as incurred, as recoverability of such expenditures is uncertain.
Accounting for Stock-Based Compensation	Accounting for Stock-Based Compensation The Company measures all stock options and other stock-based awards granted to employees and directors at the fair value on the date of the grant using the Black-Scholes option-pricing model. The fair value of the awards is recognized as expense, net of estimated forfeitures, over the requisite service period, which is generally the vesting period of the respective award. The straight-line method of expense recognition is applied to all awards with service-only conditions. Following the Company’s adoption of ASU 2018-07, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”), on January 1, 2019, for stock-based awards issued to non-employees, the Company no longer revalues non-employee awards at each reporting date and instead calculates the fair value of the awards as of the grant date using the Black-Scholes option-pricing model. Compensation expense for these awards is recognized over the related service period. The Company classifies stock-based compensation expense in its consolidated statement of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified. The Company recognizes compensation expense for only the portion of awards that are expected to vest. In developing a forfeiture rate estimate, the Company has considered its historical experience to estimate pre-vesting forfeitures for service-based awards. The impact of a forfeiture rate adjustment will be recognized in full in the period of adjustment, and if the actual forfeiture rate is materially different from the Company’s estimate, the Company may be required to record adjustments to stock-based compensation expense in future periods.
Income Taxes	Income Taxes The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in the Company’s tax returns. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.
Segment Data	Segment Data The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company’s singular focus is on advancing its bioresorbable hydrogel product candidates for the programed-release delivery of therapeutic agents, specifically for ophthalmology. All tangible assets are held in the United States. Revenue to date has been generated through product sales, all of which has been earned in the United States.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2019 and 2018, there were no items that gave rise to other comprehensive loss and therefore, there was no difference between net loss and comprehensive loss. For the year ended December 31, 2017, other comprehensive loss consisted of unrealized gains from marketable securities.
Net Loss Per Share	Net Loss Per Share The Company follows the two-class method when computing net loss per share as the Company has issued shares that meet the definition of participating securities. The two-class method determines net loss per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common stockholders for the period to be allocated between common and participating securities based on their respective rights to receive dividends as if all income for the period had been distributed. Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period. Diluted net loss attributable to common stockholders is computed by adjusting net loss attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities, including the assumed conversion of the Company’s 2026 Convertible Notes, outstanding stock options and common stock warrants, except where the result would be anti-dilutive. Diluted net loss per share attributable to common stockholders is computed by dividing the diluted net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of the conversion of the 2026 Convertible Notes, the exercise of outstanding stock options and common stock warrants. In the diluted net loss per share calculation, net loss would also be adjusted for the elimination of interest expense on the 2026 Convertible Notes (which includes amortization of the discount created upon bifurcation of the conversion option from the debt) and, the mark-to-market gain or loss each period to the bifurcated conversion option, if the impact was not anti-dilutive.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), a new standard issued to increase transparency and comparability among organizations related to their leasing activities. This standard established a right-of-use model that requires all lessees to recognize right-of-use assets and lease liabilities on their balance sheet that arise from leases as well as provide disclosures with respect to certain qualitative and quantitative information related to a company's leasing arrangements to meet the objective of allowing users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. The FASB subsequently issued the following amendments to ASU 2016-02 that have the same effective date and transition date: ASU No. 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842, ASU No. 2018-10, Codification Improvements to Topic 842, Leases, ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, ASU No. 2018-20, Narrow-Scope Improvement for Lessors, and ASU No. 2019-01, Leases (Topic 842): Codification Improvements. The Company adopted these amendments with ASU 2016-02 (collectively, the “New Leasing Standards”) effective January 1, 2019. The Company adopted the New Leasing Standards using the modified retrospective transition approach, as of January 1, 2019, with no restatement of prior periods or cumulative adjustment to accumulated deficit. Upon adoption, the Company elected the package of transition practical expedients, which allowed the Company to carry forward prior conclusions related to whether any expired or existing contracts are or contain leases, the lease classification for any expired or existing leases and initial direct costs for existing leases. The Company made an accounting policy election to not recognize leases with an initial term of 12 months or less within its consolidated balance sheets and to recognize those lease payments on a straight-line basis in its consolidated statements of operations and comprehensive loss over the lease term. Upon adoption of the New Leasing Standards the Company recognized operating lease assets of approximately $5,300 and corresponding operating lease liabilities of approximately $8,800, which are included in the Company’s consolidated balance sheet. The adoption of the New Leasing Standards did not have an impact on the Company’s consolidated statements of operations and comprehensive loss. The Company determines if an arrangement is a lease at contract inception. Operating lease assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Given the Company’s current business structure, uncertainty of future growth, and the associated impact to real estate, the Company concluded that it is not reasonably certain that any renewal options would be exercised. Therefore, the operating lease assets and operating lease liabilities only contemplate the initial lease terms. The Company uses its incremental borrowing rate when the implicit rate is not readily determinable based upon the information available at the commencement date in determining the present value of the lease payments. The Company’s operating leases are reflected in operating lease assets, current portion of operating lease liabilities and operating lease liabilities, net of current portion and in the Company’s consolidated balance sheets. The right of use asset was determined using the present value of the future minimum lease payments over the term of the lease, any lease payments made to the lessor at or before the commencement date, reduced by lease incentives, and initial direct costs incurred by the Company. The liabilities are determined using the present value of the future minimum lease payments. For additional information on the adoption of the New Leasing Standards, see Note 16 - Leases, to these consolidated financial statements. On March 31, 2019, the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”). The new standard simplifies the accounting for share-based payments to nonemployees by aligning it with the accounting for share-based payments to employees, with certain exceptions. The Company adopted ASU 2018-07 as required on January 1, 2019, and its adoption did not have any material impact on the Company’s consolidated financial statements. Recently Issued Accounting Pronouncements In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework— Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which modifies the existing disclosure requirements for fair value measurements. The new disclosure requirements include disclosure related to changes in unrealized gains or losses included in other comprehensive income (loss) for recurring Level 3 fair value measurements held at the end of each reporting period and the explicit requirement to disclose the range and weighted average of significant unobservable inputs used for Level 3 fair value measurements. The other provisions of ASU 2018-13 include eliminated and modified disclosure requirements. An entity is permitted to early adopt any removed or modified disclosures upon issuance of ASU No. 2018-13 and delay adoption of the additional disclosures until their effective date. For all entities, this guidance is required to be adopted for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. The Company is currently evaluating the impact that the adoption of ASU 2018-13 will have on its disclosures. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model. It also eliminates the concept of other-than-temporary impairment and requires credit losses related to available-for-sale debt securities to be recorded through an allowance for credit losses rather than as a reduction in the amortized cost basis of the securities. These changes will result in the earlier recognition of credit losses, if any. In May 2019, the FASB issued ASU No. 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief (“ASU 2019-05”), which provides additional implementation guidance on the previously issued ASU 2016-13. For public entities, this guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company is currently evaluating the impact that the adoption of ASU 2016-13 and ASU 2019-05 will have on its consolidated financial statements In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 (“ASU 2018-18”). ASU 2018-18 makes targeted improvements to GAAP for collaborative arrangements, including (i) clarification that certain transactions between collaborative arrangement participants should be accounted for as revenue under ASC 606 when the collaborative arrangement participant is a customer in the context of a unit of account, (ii) adding unit-of-account guidance in ASC 808, Collaborative Arrangements, to align with the guidance in ASC 606 and (iii) a requirement that in a transaction with a collaborative arrangement participant that is not directly related to sales to third parties, presenting the transaction together with revenue recognized under ASC 606 is precluded if the collaborative arrangement participant is not a customer. For public entities, this guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company is currently evaluating the impact that the adoption of ASU 2018-18 will have on its consolidated financial statements. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes Topic 740, Simplifying the Accounting for Income Taxes (“ASU 2019-12”). ASU 2019-12 removes certain exceptions for investments, intra-period allocations and interim calculations, and adds guidance to reduce complexity in accounting for income taxes. The guidance is effective for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The Company is currently evaluating the impact that the adoption of ASU 2019-12 will have on its consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - (Tables)	12 Months Ended
	Dec. 31, 2019
Summary of Significant Accounting Policies
Components of Inventory	December 31, 2019 2018 Raw materials $ 217 $ 112 Work-in-process 148 33 Finished goods 589 72 $ 954 $ 217
Reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheet to the total amounts shown in the statement of cash flows	December 31, December 31, December 31, 2019 2018 2017 Cash and cash equivalents $ $ $ Restricted cash Total cash, cash equivalents and restricted cash as shown on the statements of cash flows $ $ $

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value of Financial Assets and Liabilities
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	Fair Value Measurements as of December 31, 2019 Using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ $ 45,156 $ — $ 45,156 Liability: Derivative liability (Note 4) — — 12,124 12,124 Total $ — $ 45,156 $ 12,124 $ 57,280 Fair Value Measurements as of December 31, 2018 Using: Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ — $ 50,906 $ — $ 50,906 Total $ — $ 50,906 $ — $ 50,906

Derivative Liability (Tables)

Derivative Liability (Tables)	12 Months Ended
	Dec. 31, 2019
Derivative Liability
Summary of roll forward of the derivative liability	As of December 31, 2019 Balance at December 31, 2018 $ — Initial value 16,434 Change in fair value (4,310) Balance at December 31, 2019 $ 12,124

Convertible Notes (Tables)

Convertible Notes (Tables)	12 Months Ended
	Dec. 31, 2019
Convertible Notes
Summary of the 2026 Convertible Notes	December 31, 2019 2026 Convertible Notes $ 37,500 Less: unamortized discount (15,101) 22,399 Accrued interest 1,906 Total $ 24,305

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	12 Months Ended
	Dec. 31, 2019
Property and Equipment, net
Schedule of Property and Equipment net	December 31, 2019 2018 Equipment $ 9,511 $ 7,917 Leasehold improvements 9,074 8,675 Furniture and fixtures 1,132 760 Software 214 180 Construction in progress 239 331 20,170 17,863 Less: Accumulated depreciation and amortization (10,019) (7,627) $ 10,151 $ 10,236

Accrued Expenses and Deferred R

Accrued Expenses and Deferred Rent (Tables)	12 Months Ended
	Dec. 31, 2019
Accrued Expenses
Schedule of Accrued Expenses	December 31, December 31, 2019 2018 Accrued payroll and related expenses $ 5,042 $ 3,558 Accrued rent — 267 Accrued professional fees 1,011 1,393 Accrued research and development expenses 849 380 Accrued other 733 596 $ 7,635 $ 6,194

Notes Payable (Tables)

Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2019
Notes Payable
Schedule of borrowings outstanding	December 31, December 31, 2019 2018 Borrowings outstanding $ 25,000 $ 25,000 Accrued exit fee 180 5 Unamortized discount $ 25,007 $ 24,788
Schedule of Annual Repayment Requirements for Credit Facility	Interest and Year Ending December 31, Principal Final Payment Total 2020 — 2,481 2,481 2021 8,333 2,094 10,427 2022 8,333 1,269 9,602 2023 8,334 1,320 9,654 $ 25,000 $ 7,164 $ 32,164

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	12 Months Ended
	Dec. 31, 2019
Stock-Based Awards
Schedule of Assumptions Used to Determine Fair Value of Stock Options Granted to Employees and Directors Presented on Weighted Average Basis	Year Ended December 31, 2019 2018 2017 Risk-free interest rate 2.25 % 2.65 % 2.00 % Expected term (in years) 6 6 6 Expected volatility % 102 % 102 % Expected dividend yield — % — % — %
Schedule of Stock Option Activity	Weighted Weighted Average Average Remaining Aggregate Shares Issuable Exercise Contractual Intrinsic Under Options Price Term Value (In years) Outstanding as of December 31, 2018 5,230,831 $ 8.67 7.5 $ 654 Granted 3,985,025 4.06 Exercised (28,583) 2.72 Forfeited (1,266,856) 6.84 Outstanding as of December 31, 2019 7,920,417 $ 6.67 7.6 $ 704 Options vested and expected to vest as of December 31, 2019 7,065,332 $ 6.96 7.3 $ — Options exercisable as of December 31, 2019 3,790,742 $ 8.67 6.0 $ 651
Schedule of Stock-Based Compensation Expense Related to Stock Options and Restricted Common Stock	Year Ended December 31, 2019 2018 2017 Research and development $ 2,312 $ 2,557 $ 2,584 Selling and marketing 1,013 449 633 General and administrative 5,434 4,477 4,104 $ 8,759 $ 7,483 $ 7,321

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2019
Net Loss Per Share
Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	Year Ended December 31, 2019 2018 2017 Numerator: Net loss attributable to common stockholders $ (86,372) $ (59,978) $ (63,386) Denominator: Weighted average common shares outstanding, basic and diluted 45,273,231 38,115,142 28,818,196 Net loss per share attributable to common stockholders, basic and diluted $ (1.91) $ (1.57) (2.20)
Schedule of Antidilutive Securities, Excluded from Computation of Diluted Net Loss per Share	December 31, 2019 2018 2017 Options to purchase common stock 7,920,417 5,230,831 4,002,374 Shares issuable upon conversion of 2026 Convertible Notes, if converted 5,769,232 — — Warrants for the purchase of common stock 18,939 18,939 18,939 13,708,588 5,249,770 4,021,313

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases
Summary of the presentation in the Company's consolidated balance sheet of its operating leases	December 31, Balance sheet location 2019 Assets: Operating lease assets Operating lease assets $ Liability: Current operating lease liabilities Operating lease liabilities $ Non-current operating lease liabilities Operating lease liabilities, net of current portion Total Operating lease liabilities: $
Summary of lease cost	For the Year Ended December 31, Statement of operations and comprehensive loss location 2019 Operating lease costs Research and development $ Selling and marketing General and administrative $ 2,215
Schedule of minimum lease payments	December 31, Year Ending December 31, 2019 2020 2,432 2021 2,483 2022 2,548 2023 2,357 2024 1,569 Thereafter 3,813 Total lease payments $ 15,202 Less: interest 5,171 Present value of operating lease liabilities $ 10,031
Supplemental disclosure of cash flow information related to our operating leases included in cash flows provided by operating activities	For the Year Ended December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities $
Schedule of future minimum lease payments under prior guidance	2019 2020 2021 2022 2023 Thereafter Total Minimum lease payments $ $

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Taxes
Reconciliation of Federal Income Tax Rate	Year Ended December 31, 2019 2018 2017 Federal statutory income tax rate 21.0 % 21.0 % 34.0 % Tax reform change — — (43.0) Research and development tax credits 2.1 3.6 3.3 State taxes, net of federal benefit 2.7 4.5 3.8 Stock-based compensation (1.3) (1.3) (2.2) Other (0.5) (0.1) 0.2 Change in deferred tax asset valuation allowance (24.0) (27.7) 3.9 Effective income tax rate — % — % — %
Net Deferred Tax Assets	December 31, 2019 2018 Deferred tax assets: Net operating loss carryforwards $ 70,317 $ 49,699 Tax credit carryforwards 11,966 10,160 Capitalized start-up costs 695 870 Capitalized research and development expenses, net 14,521 18,418 Operating lease liabilities 2,505 — Derivative liability 3,028 — Accrued expenses and other temporary differences 6,987 5,196 Total deferred tax assets 110,019 84,343 Valuation allowance (105,062) (84,343) Net deferred tax assets 4,957 — Deferred tax liabilities: Operating lease right of use assets (1,662) — 2026 Convertible Notes (3,295) — Total deferred tax liabilities (4,957) — Net deferred tax assets $ — $ —
Changes in Valuation Allowance for Deferred Tax Assets	Year Ended December 31, 2019 2018 2017 Valuation allowance as of beginning of year $ 84,343 $ 67,726 $ 70,236 Increases recorded to income tax provision 20,719 16,617 24,773 Decreases recorded to income tax provision — — (27,283) Valuation allowance as of end of year $ 105,062 $ 84,343 $ 67,726

Restructuring and Other Costs (

Restructuring and Other Costs (Tables)	12 Months Ended
	Dec. 31, 2019
Restructuring and Other Costs
Summary of restructuring and other costs by category	wwe Twelve Months Ended Total Research and development $ Selling and marketing General and administration $

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Selected Quarterly Financial Data (Unaudited)
Schedule of Quarterly Financial Data	Three Months Ended Dec. 31, Sept. 30, June 30, Mar 31, Dec. 31, Sept. 30, June 30, Mar 31, 2019 2019 2019 2019 2018 2018 2018 2018 Statements of Operations Data: Revenue 2,256 829 650 492 504 498 648 340 Loss from operations (21,401) (23,144) (21,599) (19,658) (17,283) (14,816) (13,564) (13,455) Net loss (26,017) (18,778) (24,453) (17,124) (17,399) (15,010) (13,804) (13,765) Basic net loss per common share $ (0.53) $ (0.40) $ (0.57) $ (0.41) $ (0.42) $ (0.38) $ (0.37) $ (0.40) Diluted net loss per common share $ (0.53) $ (0.45) $ (0.57) $ (0.45) $ (0.42) $ (0.38) $ (0.37) $ (0.40)

Nature of the Business and Ba_2

Nature of the Business and Basis of Presentation - Nature of Business (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Nature of the Business and Basis of Presentation
Cash and cash equivalents	$ 54,437	$ 54,062	$ 41,538
Accumulated deficit	$ 383,615	$ 297,243

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Inventory Valuation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Inventory
Raw materials	$ 217	$ 112
Work-in-process	148	33
Finished goods	589	72
Total inventory	$ 954	$ 217

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Thousands	Aug. 02, 2019	Aug. 01, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows:
Cash and cash equivalents			$ 54,437	$ 54,062	$ 41,538
Restricted cash			1,764	6,614	1,614
Total cash, cash equivalents and restricted cash as shown on the statement of cash flow			56,201	60,676	$ 43,152	$ 34,664
Credit Agreement
Restricted Cash
Total indebtedness			25,000	25,000
Minimum cash in hand as a financial covenant	$ 5,000	$ 5,000	5,000
Security deposit
Reconciliation of the cash, cash equivalents, and restricted cash reported within the balance sheet that sum to the total of the same amounts shown in the statement of cash flows:
Restricted cash			$ 1,764	$ 6,614

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Concentration of Credit Risk (Details) - Customer	12 Months Ended
	Dec. 31, 2019customer
Total revenue
Concentration risk
Number of major customers	2
Total revenue | Customer one
Concentration risk
Concentration risk	27.00%
Total revenue | Customer two
Concentration risk
Concentration risk	11.00%
Accounts receivable
Concentration risk
Number of major customers	3
Accounts receivable | Customer one
Concentration risk
Concentration risk	39.00%
Accounts receivable | Customer two
Concentration risk
Concentration risk	18.00%
Accounts receivable | Customer three
Concentration risk
Concentration risk	11.00%

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Fair Value Measurements and Derivative Liability (Details) - 2026 Convertible Notes - USD ($) $ in Thousands	Mar. 01, 2019	Dec. 31, 2019
Fair Value Measurements and Derivative Liability
Convertible notes issued	$ 37,500	$ 37,500
Convertible notes at amortized cost		24,305
Estimated fair value		$ 36,849
Maximum beneficial ownership percent	19.99%

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019
Summary Of Significant Accounting Policies
Income tax examination, likelihood of settlement, description	The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement.
Minimum
Summary Of Significant Accounting Policies
Property and equipment, estimated useful life	3 years
Income tax examination, likelihood of settlement, percentage	50.00%
Maximum
Summary Of Significant Accounting Policies
Property and equipment, estimated useful life	5 years

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - ASU 2016-02 (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019
Recently Issued Accounting Pronouncements
Operating lease assets	$ 6,655
Operating lease liabilities	$ 10,031
Adjustment | Accounting Standards Update 2016-02
Recently Issued Accounting Pronouncements
Operating lease assets		$ 5,300
Operating lease liabilities		$ 8,800

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Liability:
Derivative liability	$ 12,124
Recurring Basis
Assets:
Total assets at fair value		$ 50,906
Liability:
Derivative liability	12,124
Fair Value, Net Asset (Liability), Total	57,280
Money Market Funds | Recurring Basis
Assets:
Cash equivalents	45,156	50,906
Level 2 | Recurring Basis
Assets:
Total assets at fair value		50,906
Liability:
Fair Value, Net Asset (Liability), Total	45,156
Level 2 | Money Market Funds | Recurring Basis
Assets:
Cash equivalents	45,156	$ 50,906
Level 3 | Recurring Basis
Liability:
Derivative liability	12,124
Fair Value, Net Asset (Liability), Total	$ 12,124

Fair Value of Financial Asset_4

Fair Value of Financial Assets and Liabilities - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value of Financial Assets and Liabilities
Transfers between fair value measurement levels	$ 0	$ 0

Derivative Liability - Other (D

Derivative Liability - Other (Details) $ in Thousands	Dec. 31, 2019USD ($)
Derivative Liability
Derivative liability, fair value	$ 12,124
2026 Convertible Notes | Conversion price
Derivative Liability
Debt instrument, measurement input	3.95
2026 Convertible Notes | Expected annual volatility
Derivative Liability
Debt instrument, measurement input	0.86
2026 Convertible Notes | Discount yield
Derivative Liability
Debt instrument, measurement input	0.130

Derivative Liability - Roll for

Derivative Liability - Roll forward (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Roll forward of the derivative liability
Initial value	$ 16,434
Change in fair value	(4,310)
Balance at end of period	$ 12,124

Convertible Notes - Other (Deta

Convertible Notes - Other (Details)	Mar. 01, 2019USD ($)D$ / shares	Dec. 31, 2019USD ($)$ / shares	Dec. 31, 2018$ / shares
Senior Convertible Notes
Common stock, par value | $ / shares		$ 0.0001	$ 0.0001
2026 Convertible Notes
Senior Convertible Notes
Convertible notes issued | $	$ 37,500,000	$ 37,500,000
Interest rate (as a percent)	6.00%
Effective annual interest rate (as a percent)		14.80%
Common stock, par value | $ / shares	$ 0.0001
Maximum beneficial ownership percent	19.99%
Conversion rate	153.8462
Principal amount of debt that is used in conversion calculations | $	$ 1,000
Initial conversion price | $ / shares	$ 6.50
Debt repurchase price percent	100.00%
Consecutive trading days | D	20
Percentage of product of conversion rate and daily VWAP	5.00%
Percentage of outstanding principal amount	100.00%
2026 Convertible Notes | On or after March 1, 2022
Senior Convertible Notes
Debt repurchase price percent	100.00%
Consecutive trading days | D	30
Minimum percentage of common stock for conversion of debt	130.00%
Consecutive proceeding trading days for conversion of purchase price | D	20

Convertible Notes - Summary (De

Convertible Notes - Summary (Details) - 2026 Convertible Notes - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 01, 2019
Senior Convertible Notes
2026 Convertible notes	$ 37,500	$ 37,500
Less: unamortized discount	(15,101)
Carrying amount, excluding deferred interest	22,399
Accrued interest	1,906
Total	$ 24,305

Property and Equipment, net - S

Property and Equipment, net - Schedule of Property and Equipment, net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property and Equipment, net
Property and equipment, gross	$ 20,170	$ 17,863
Less: Accumulated depreciation and amortization	(10,019)	(7,627)
Property and equipment, net	10,151	10,236
Equipment
Property and Equipment, net
Property and equipment, gross	9,511	7,917
Leasehold Improvements
Property and Equipment, net
Property and equipment, gross	9,074	8,675
Furniture and Fixtures
Property and Equipment, net
Property and equipment, gross	1,132	760
Software
Property and Equipment, net
Property and equipment, gross	214	180
Construction in Progress
Property and Equipment, net
Property and equipment, gross	$ 239	$ 331

Property and Equipment, net - A

Property and Equipment, net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment, net
Depreciation and amortization expense	$ 2,530	$ 2,286	$ 1,625

Accrued Expenses - Summary (Det

Accrued Expenses - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued Expenses
Accrued payroll and related expenses	$ 5,042	$ 3,558
Accrued rent		267
Accrued professional fees	1,011	1,393
Accrued research and development expenses	849	380
Accrued other	733	596
Total	$ 7,635	$ 6,194

Collaboration Agreements - Addi

Collaboration Agreements - Additional Information (Details) - Collaboration Agreement - Regeneron $ in Thousands	Oct. 10, 2016USD ($)
Collaboration Agreement
Payment receivable upon exercise of option	$ 10,000
Maximum
Collaboration Agreement
Reimbursable clinical development costs	25,000
Potential increase in reimbursable clinical development costs	5,000
Potential payment receivable per Licensed Product upon the achievement of specified development and regulatory milestones	145,000
Potential payment receivable per Licensed Product upon first commercial sale of such Licensed Product	100,000
Potential payment receivable due for achievement of specified sales milestones for all Licensed Products	$ 50,000

Notes Payable - Additional Info

Notes Payable - Additional Information (Details) - Credit Agreement $ in Thousands	Aug. 02, 2019USD ($)	Aug. 01, 2019USD ($)	Dec. 31, 2018USD ($)installment	Dec. 31, 2019USD ($)
Notes Payable
Borrowing capacity under the agreement				$ 25,000
Borrowings outstanding			$ 25,000	25,000
Repayments of debt, Principal				25,000
Number of equal monthly installments | installment			36
Outstanding borrowings under credit facility, net of unamortized discount			$ 25,000
Final payment due (as a percent)			3.50%
Additional final payment			$ 875	875
Minimum cash in hand as a financial covenant	$ 5,000	$ 5,000		5,000
2021
Notes Payable
Required monthly principal payment			694
Repayments of debt, Principal				$ 8,333
Achievement of certain milestones
Notes Payable
Repayments of debt, Principal			$ 1,042
Number of equal monthly installments | installment			24
LIBOR
Notes Payable
Borrowings outstanding			$ 25,000
Effective annual interest rate (as a percent)			9.76%
Interest rate floor (as a percent)			2.00%
Basis spread (as a percent)			7.25%

Notes Payable - Borrowings Outs

Notes Payable - Borrowings Outstanding (Details) - Credit Agreement - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Notes Payable
Borrowings outstanding	$ 25,000	$ 25,000
Accrued exit fee	180	5
Less: unamortized discount	173	217
Borrowings	$ 25,007	$ 24,788

Notes Payable - Schedule of Ann

Notes Payable - Schedule of Annual Repayment Requirements for Credit Facility (Details) - Credit Agreement $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Annual repayment requirements
Credit Facility, Principal	$ 25,000
Credit Facility, Interest and Final Payment	7,164
Credit Facility, Total	32,164
2020
Annual repayment requirements
Credit Facility, Interest and Final Payment	2,481
Credit Facility, Total	2,481
2021
Annual repayment requirements
Credit Facility, Principal	8,333
Credit Facility, Interest and Final Payment	2,094
Credit Facility, Total	10,427
2022
Annual repayment requirements
Credit Facility, Principal	8,333
Credit Facility, Interest and Final Payment	1,269
Credit Facility, Total	9,602
2023
Annual repayment requirements
Credit Facility, Principal	8,334
Credit Facility, Interest and Final Payment	1,320
Credit Facility, Total	$ 9,654

Warrants - Additional Informati

Warrants - Additional Information (Details) - Warrants for Common Stock	Dec. 31, 2019$ / sharesshares
Warrants
Number of shares callable by warrants | shares	18,939
Weighted Average
Warrants
Weighted average exercise price to purchase common stock | $ / shares	$ 7.92

Preferred Stock (Details)

Preferred Stock (Details) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Preferred Stock
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Common Stock (Details)

Common Stock (Details) $ / shares in Units, $ in Thousands	Apr. 05, 2019USD ($)	Jan. 31, 2018USD ($)$ / sharesshares	Nov. 30, 2016USD ($)	Mar. 31, 2019USD ($)shares	Dec. 31, 2019USD ($)Voteshares	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)shares	Dec. 31, 2018USD ($)shares	Mar. 31, 2019USD ($)shares	Feb. 25, 2019USD ($)	Jan. 01, 2015shares	Dec. 31, 2014shares
Common Stock
Common stock, shares authorized | shares					100,000,000	100,000,000		100,000,000
Number of votes per share | Vote					1
Voting right description					Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company's stockholders.
Net proceeds from issuance of common stock					$ 37,537	$ 61,571	$ 29,238
Common Stock
Common Stock
Number of shares issued | shares					8,655,940	11,596,173	4,359,920
Common Stock | 2016 Sales Agreement
Common Stock
Maximum aggregate proceeds from offering			$ 40,000
Number of shares issued | shares				1,318,481		4,121,173		5,011,741	6,330,222
Net proceeds from issuance of common stock				$ 4,954		$ 26,824		$ 33,427	$ 38,381
Aggregate value available for issuance										$ 0
Common Stock | 2019 Sales Agreement
Common Stock
Maximum aggregate proceeds from offering	$ 50,000
Number of shares issued | shares					7,337,459
Net proceeds from issuance of common stock					$ 32,626
Common Stock | Follow-on Offering
Common Stock
Common stock, price per share | $ / shares		$ 5
Number of shares issued | shares		7,475,000
Net proceeds from issuance of common stock		$ 34,704
2014 Stock Incentive Plan | Common Stock
Common Stock
Common stock shares, reserved | shares					9,499,615						2,126,907	1,336,907

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Details) - Common Stock - shares	Jan. 01, 2019	Jan. 01, 2015	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2014
Stock-Based Awards
Issuance of common stock in connection with employee stock purchase plan, shares			130,945	81,455	53,662
2014 Stock Incentive Plan
Stock-Based Awards
Number of shares of common stock authorized for issuance		2,126,907	9,499,615			1,336,907
Increased number of shares of common stock reserved for issuance		1,659,218
Additional number of shares of common stock , percentage		4.00%
Additional number of shares authorized for issuance	1,659,218
Number of shares of common stock available for issuance			636,292
Unvested service-based stock options held by nonemployees			0
2014 Employee Stock Purchase Plan
Stock-Based Awards
Number of shares of common stock authorized for issuance		232,402				207,402
Increased number of shares of common stock reserved for issuance	207,402	207,402
Additional number of shares of common stock , percentage		0.50%
Number of shares of common stock available for issuance			477,967

Stock-Based Awards - Inducement

Stock-Based Awards - Inducement Stock Option Awards (Detail) - $ / shares	Jul. 09, 2019	Jun. 20, 2017	Dec. 31, 2019	Jul. 29, 2019
Stock-Based Awards
Shares Issuable Under Options, Granted			3,985,025
Exercise price (in dollars per share)			$ 4.06
Non-statutory Stock Option | Management
Stock-Based Awards
Shares Issuable Under Options, Granted	60,000	590,000
Exercise price (in dollars per share)	$ 5.13	$ 10.94
Vesting period	4 years	4 years
Percentage of shares underlying the option award vesting on first anniversary	25.00%	25.00%
Percentage of shares underlying the option award vesting monthly after the first anniversary	75.00%	75.00%
Number of shares of common stock authorized for issuance			446,000	500,000

Stock-Based Awards - Fair Value

Stock-Based Awards - Fair Value Assumptions (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assumptions Used to Determine Fair Value of Stock Options Granted to Employees and Directors Presented on a Weighted Average Basis
Risk-free interest rate	2.25%	2.65%	2.00%
Expected term (in years)	6 years	6 years	6 years
Expected volatility	87.00%	102.00%	102.00%

Stock-Based Awards - Schedule o

Stock-Based Awards - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares Issuable Under Options
Shares Issuable Under Options, Beginning balance	5,230,831
Shares Issuable Under Options, Granted	3,985,025
Shares Issuable Under Options, Exercised	(28,583)
Shares Issuable Under Options, Forfeited	(1,266,856)
Shares Issuable Under Options, Ending balance	7,920,417	5,230,831
Shares Issuable Under Options, Vested and expected to vest	7,065,332
Shares Issuable Under Options, Exercisable	3,790,742
Weighted Average Exercise Price
Weighted Average Exercise Price, Beginning balance	$ 8.67
Weighted Average Exercise Price, Granted	4.06
Weighted Average Exercise Price, Exercised	2.72
Weighted Average Exercise Price, Forfeited	6.84
Weighted Average Exercise Price, Ending balance	6.67	$ 8.67
Weighted Average Exercise Price, Vested and expected to vest	6.96
Weighted Average Exercise Price, Exercisable	$ 8.67
Weighted Average Remaining Contractual Term	7 years 7 months 6 days	7 years 6 months
Weighted Average Remaining Contractual Term, Vested and Expected to vest	7 years 3 months 18 days
Weighted Average Remaining Contractual Term, Exercisable	6 years
Other disclosures
Aggregate Intrinsic Value	$ 704	$ 654
Aggregate Intrinsic Value, Exercisable	651
Aggregate intrinsic value of stock options exercised	$ 54	$ 551	$ 408
Weighted average fair value of stock option granted	$ 2.99	$ 4.48	$ 6.44

Stock-Based Awards - Stock-Base

Stock-Based Awards - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock-based Compensation
Stock-based compensation expense	$ 8,759	$ 7,483	$ 7,321
Unrecognized stock-based compensation cost	$ 10,566
Weighted average period of unrecognized stock-based compensation cost expected to be recognized	2 years 6 months
Research and Development Expense
Stock-based Compensation
Stock-based compensation expense	$ 2,312	2,557	2,584
Selling and Marketing Expense
Stock-based Compensation
Stock-based compensation expense	1,013	449	633
General and Administrative Expense
Stock-based Compensation
Stock-based compensation expense	$ 5,434	$ 4,477	$ 4,104

Net Loss Per Share - Basic Net

Net Loss Per Share - Basic Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic and diluted net loss per share attributable to common stockholders:
Net loss attributable to common stockholders	$ (26,017)	$ (18,778)	$ (24,453)	$ (17,124)	$ (17,399)	$ (15,010)	$ (13,804)	$ (13,765)	$ (86,372)	$ (59,978)	$ (63,386)
Weighted average common shares outstanding, basic and diluted									45,273,231	38,115,142	28,818,196
Net loss per share attributable to common stockholders, basic and diluted									$ (1.91)	$ (1.57)	$ (2.20)

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Antidilutive Securities, Excluded from Computation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share
Total common stock equivalents	13,708,588	5,249,770	4,021,313
Options to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Total common stock equivalents	7,920,417	5,230,831	4,002,374
2026 Convertible Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share
Total common stock equivalents	5,769,232
Warrant | Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Total common stock equivalents	18,939	18,939	18,939

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Oct. 10, 2016	Dec. 31, 2019	Dec. 31, 2018
Incept
Commitments and Contingencies
Payments for Royalties		$ 306
Regeneron | Collaboration Agreement
Commitments and Contingencies
Payments made under the collaboration agreement			$ 0
Regeneron | Collaboration Agreement | Maximum
Commitments and Contingencies
Reimbursable clinical development costs	$ 25,000
Potential increase in reimbursable clinical development costs	$ 5,000

Leases - Other (Details)

Leases - Other (Details) $ in Thousands	Apr. 18, 2019ft²	Oct. 31, 2017	Jun. 30, 2016ft²period	Dec. 31, 2019USD ($)period
Leases
Options to renew				true
Additional right of use asset and related lease liability				$ 2,044
Operating lease asset				6,655
Operating lease liability				$ 10,031
Minimum
Leases
Lease term				1 year
Renewal terms				1 year
Additional periods for renewal | period				1
Maximum
Leases
Lease term				8 years
Renewal terms				6 years
Office space lease, Bedford, Massachusetts
Leases
Lease term	5 years
Options to renew	false
Area covered under lease | ft²	30,036
Lease Agreement, June 2016, Bedford, Massachusetts
Leases
Options to renew			true
Renewal terms			5 years
Additional periods for renewal | period			2
Area covered under lease | ft²			70,712
Lease Agreement, June 2016, Bedford, Massachusetts | Minimum
Leases
Written notice period to extend the lease			12 months
Lease Agreement, June 2016, Bedford, Massachusetts | Maximum
Leases
Written notice period to extend the lease			15 months
Laboratory and manufacturing space lease
Leases
Option to terminate		true

Leases - Balance sheet presenta

Leases - Balance sheet presentation (Details) $ in Thousands	Dec. 31, 2019USD ($)
Assets
Operating lease assets	$ 6,655
Liabilities
Current operating lease liabilities	1,126
Noncurrent operating lease liabilities	8,905
Total operating lease liabilities	$ 10,031

Leases - Operating lease costs

Leases - Operating lease costs (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Leases
Operating lease costs	$ 2,215
Research and Development Expense
Leases
Operating lease costs	1,638
Selling and Marketing Expense
Leases
Operating lease costs	262
General and Administrative Expense
Leases
Operating lease costs	$ 315

Leases - Future minimum payment

Leases - Future minimum payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Minimum lease payments
2020	$ 2,432
2021	2,483
2022	2,548
2023	2,357
2024	1,569
Thereafter	3,813
Total lease payments	15,202
Less: interest	5,171
Present value of operating lease liabilities	10,031
Supplemental disclosure of cash flow information related to operating leases
Operating Lease, Payments	2,215
Rental expense
Rental expense	$ 2,226	$ 1,788	$ 1,733

Leases - Commitments under prio

Leases - Commitments under prior lease guidance (Details) $ in Thousands	Dec. 31, 2019USD ($)
Minimum lease payments
2019	$ 1,809
2020	1,850
2021	1,886
2022	1,936
2023	1,730
Thereafter	5,224
Total	$ 14,435

Leases - Terms and discount rat

Leases - Terms and discount rate (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Leases
Weighted average remaining lease term in years	6 years 5 months 19 days
Weighted-average incremental borrowing rate	13.55%
Supplemental disclosure of cash flow information related to operating leases
Cash paid for amounts included in the measurement of lease liabilities	$ 2,215

Income Taxes - U.S. Tax Reform

Income Taxes - U.S. Tax Reform (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Corporate tax rate	21.00%	21.00%	34.00%

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Federal Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Income tax benefit	$ 0	$ 0	$ 0
Reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate
Federal statutory income tax rate	21.00%	21.00%	34.00%
Tax reform change			(43.00%)
Research and development tax credits	2.10%	3.60%	3.30%
State taxes, net of federal benefit	2.70%	4.50%	3.80%
Stock-based compensation	(1.30%)	(1.30%)	(2.20%)
Other	(0.50%)	(0.10%)	0.20%
Change in deferred tax asset valuation allowance	(24.00%)	(27.70%)	3.90%

Income Taxes - Net Deferred Tax

Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating loss carryforwards	$ 70,317	$ 49,699
Tax credit carryforwards	11,966	10,160
Capitalized start-up costs	695	870
Capitalized research and development expenses, net	14,521	18,418
Operating lease liabilities	2,505
Derivative liability	3,028
Accrued expenses and other temporary differences	6,987	5,196
Total gross deferred tax assets	110,019	84,343
Valuation allowance	(105,062)	$ (84,343)	$ (67,726)	$ (70,236)
Net deferred tax assets	4,957
Operating lease right of use assets	(1,662)
2026 Convertible Notes	(3,295)
Total deferred tax liabilities	$ (4,957)

Income Taxes - Changes in Valua

Income Taxes - Changes in Valuation Allowance for Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Valuation allowance as of beginning of year	$ 84,343	$ 67,726	$ 70,236
Increases recorded to income tax provision	20,719	16,617	24,773
Decreases recorded to income tax provision			(27,283)
Valuation allowance as of end of year	$ 105,062	$ 84,343	$ 67,726

Income Taxes - Net Operating Lo

Income Taxes - Net Operating Loss Carryforwards (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Federal
Net operating loss carryforwards
Net operating loss carryforwards	$ 274,331
Net operating loss carryforward that can be carried forward indefinitely	148,250	$ 148,250
State
Net operating loss carryforwards
Net operating loss carryforwards	$ 219,375

Income Taxes - Tax Credit Carry

Income Taxes - Tax Credit Carryforwards (Details) - Research and Development $ in Thousands	Dec. 31, 2019USD ($)
Federal
Tax credit carryforwards
Tax credit carryforwards	$ 8,211
State
Tax credit carryforwards
Tax credit carryforwards	$ 4,342

Income Taxes - Other (Details)

Income Taxes - Other (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Taxes
Increased ownership percentage	50.00%
Unrecognized tax benefits	$ 0	$ 0
Accrued interest or penalties related to uncertain tax positions	0	0
Interest expense or penalties related to uncertain tax positions	$ 0	$ 0

401(k) Savings Plan - Additiona

401(k) Savings Plan - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
401(k) Savings Plan
Contributions to savings plan	$ 0

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - McCarter - Legal Fees - Senior Vice President - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transactions
Expenses incurred	$ 1,119	$ 1,019	$ 42
Due to related parties	107	$ 526
Accrued expenses	$ 242

Restructuring and Other Costs -

Restructuring and Other Costs - Summary (Details) $ in Thousands	Nov. 06, 2019	Jul. 31, 2017position	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2017USD ($)
Restructuring and other costs
Restructuring and other costs				$ 2,506
Research and Development Expense
Restructuring and other costs
Restructuring and other costs				690
Selling and Marketing Expense
Restructuring and other costs
Restructuring and other costs				1,399
General and Administrative Expense
Restructuring and other costs
Restructuring and other costs				$ 417
Ankerud Transition Agreement
Restructuring and other costs
Severance expense					$ 386
Fortune Transition Agreement
Restructuring and other costs
Severance expense					417
Elimination of portion of Company's workforce
Positions eliminated
Restructuring And Related Activities, Decrease In Head Count, Percentage	22.00%
Number of positions eliminated | position		30
Restructuring and other costs
Restructuring and other costs			$ 554		$ 1,703

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) - Schedule of Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statements of Operations Data:
Revenue from Contract with Customer, Excluding Assessed Tax	$ 2,256	$ 829	$ 650	$ 492	$ 504	$ 498	$ 648	$ 340	$ 4,227	$ 1,990	$ 1,923
Loss from operations	(21,401)	(23,144)	(21,599)	(19,658)	(17,283)	(14,816)	(13,564)	(13,455)	(85,802)	(59,118)	(61,923)
Net loss	$ (26,017)	$ (18,778)	$ (24,453)	$ (17,124)	$ (17,399)	$ (15,010)	$ (13,804)	$ (13,765)	$ (86,372)	$ (59,978)	$ (63,386)
Basic net loss per common share	$ (0.53)	$ (0.40)	$ (0.57)	$ (0.41)	$ (0.42)	$ (0.38)	$ (0.37)	$ (0.40)
Diluted net loss per common share	$ (0.53)	$ (0.45)	$ (0.57)	$ (0.45)	$ (0.42)	$ (0.38)	$ (0.37)	$ (0.40)

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Thousands	Jan. 01, 2020	Jan. 01, 2019	Jan. 01, 2015	Feb. 19, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Subsequent Events
Net proceeds from issuance of common stock					$ 37,537	$ 61,571	$ 29,238
Common Stock
Subsequent Events
Number of shares issued					8,655,940	11,596,173	4,359,920
Common Stock | 2014 Stock Incentive Plan
Subsequent Events
Increased number of shares of common stock reserved for issuance			1,659,218
Additional number of shares of common stock , percentage			4.00%
Additional number of shares authorized for issuance		1,659,218
Common Stock | 2014 Employee Stock Purchase Plan
Subsequent Events
Increased number of shares of common stock reserved for issuance		207,402	207,402
Additional number of shares of common stock , percentage			0.50%
Subsequent Event | Common Stock | 2019 Sales Agreement
Subsequent Events
Number of shares issued				2,229,514
Net proceeds from issuance of common stock				$ 10,686
Subsequent Event | Common Stock | 2014 Stock Incentive Plan
Subsequent Events
Additional number of shares authorized for issuance	1,659,218
Subsequent Event | Common Stock | 2014 Employee Stock Purchase Plan
Subsequent Events
Additional number of shares authorized for issuance	207,402