Kala Pharmaceuticals (KALA) 10-K 25 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 24, 2021	Jun. 30, 2020
Document and Entity Information
Entity Registrant Name	KALA PHARMACEUTICALS, INC.
Entity Central Index Key	0001479419
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity File Number	001-38150
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-0604595
Entity Address, Address Line One	490 Arsenal Way, Suite 120
Entity Address, City or Town	Watertown
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02472
City Area Code	781
Local Phone Number	996-5252
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	KALA
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
ICFR Auditor Attestation Flag	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		61,552,352
Entity Shell Company	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 411.8

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 77,264	$ 85,449
Short-term investments	76,276
Accounts receivable, net	9,604	11,563
Inventory	5,229	4,648
Prepaid expenses and other current assets	3,006	3,824
Total current assets	171,379	105,484
Non-current assets:
Property and equipment, net	3,166	2,698
Long-term inventory	6,219	3,778
Right-of-use assets	27,853	29,781
Restricted cash and other long-term assets	12,989	12,582
Total assets	221,606	154,323
Current liabilities:
Accounts payable	1,724	2,518
Accrued expenses and other current liabilities	18,971	20,929
Current portion of lease liabilities	1,530	1,327
Total current liabilities	22,225	24,774
Long-term liabilities:
Long-term lease liabilities	27,143	28,673
Long-term debt	72,243	71,184
Total long-term liabilities	99,386	99,857
Total liabilities	121,611	124,631
Commitments and Contingencies (Note 15)
Stockholders' equity:
Common stock, $0.001 par value; 120,000,000 shares authorized as of December 31, 2020 and December 31, 2019; 58,915,375 and 36,086,254 shares issued and outstanding as of December 31, 2020 and December 31, 2019, respectively	59	36
Additional paid-in capital	499,715	325,112
Accumulated other comprehensive income	4
Accumulated deficit	(399,783)	(295,456)
Total stockholders' equity	99,995	29,692
Total liabilities and stockholders' equity	$ 221,606	$ 154,323

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED BALANCE SHEETS
Preferred stock, authorized	5,000,000	5,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, authorized	120,000,000	120,000,000
Common stock, shares issued	58,915,375	36,086,254
Common stock, shares outstanding	58,915,375	36,086,254

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED STATEMENTS OF OPERATIONS
Product revenues, net	$ 6,362	$ 6,074
Costs and expenses:
Cost of product revenues	3,173	2,008
Selling, general and administrative	81,068	65,015
Research and development	18,352	27,275
Total costs and expenses	102,593	94,298
Loss from operations	(96,231)	(88,224)
Other income (expense):
Interest and other income	493	2,357
Interest and other expense	(8,589)	(8,480)
Total interest and other expense	(8,096)	(6,123)
Net loss	$ (104,327)	$ (94,347)
Net loss per share-basic and diluted	$ (1.99)	$ (2.76)
Weighted average shares outstanding-basic and diluted	52,377,526	34,209,756
Statement of Comprehensive Income
Net loss	$ (104,327)	$ (94,347)
Other comprehensive income:
Change in unrealized gains/losses on investments	4
Total other comprehensive income	4
Total comprehensive loss	$ (104,323)	$ (94,347)

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Total
Balance as of beginning of period at Dec. 31, 2018	$ 34	$ 306,053		$ (201,109)	$ 104,978
Balance as of beginning of period (in shares) at Dec. 31, 2018	33,863,077
Stockholders' Equity
At the market offering, net of offering costs	$ 2	8,423			8,425
At the market offering, net of offering costs (in shares)	2,074,799
Exercise of stock options		42			42
Exercise of stock options (in shares)	24,714
Issuance under employee stock purchase plan		545			545
Issuance under employee stock purchase plan (in shares)	123,664
Stock-based compensation expense		10,049			10,049
Net loss				(94,347)	(94,347)
Balance as of end of period at Dec. 31, 2019	$ 36	325,112		(295,456)	29,692
Balance as of end of period (in shares) at Dec. 31, 2019	36,086,254
Stockholders' Equity
At the market offering, net of offering costs	$ 5	33,129			33,134
At the market offering, net of offering costs (in shares)	5,173,730
Exercise of stock options	$ 1	1,086			1,087
Exercise of stock options (in shares)	345,479
Issuance under employee stock purchase plan		1,016			1,016
Issuance under employee stock purchase plan (in shares)	314,397
Common stock offering, net of offering costs	$ 17	125,406			125,423
Common stock offering, net of offering costs (in shares)	16,979,371
Stock-based compensation expense		13,966			13,966
Warrant exercises (in shares)	16,144
Change in fair value of investments			$ 4		4
Net loss				(104,327)	(104,327)
Balance as of end of period at Dec. 31, 2020	$ 59	$ 499,715	$ 4	$ (399,783)	$ 99,995
Balance as of end of period (in shares) at Dec. 31, 2020	58,915,375

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY
Issuance cost and underwriting fees	$ 8,475
Sales agent commission	$ 1,026	$ 262

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (104,327)	$ (94,347)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	912	843
Non-cash operating lease cost	1,928	1,773
Amortization of debt discount and other non-cash interest	1,059	958
Stock-based compensation	13,312	9,991
Amortization of discount on available-for-sale securities	(5)
Change in operating assets and liabilities:
Accounts receivable	1,959	(11,563)
Prepaid expenses and other current assets	818	(1,789)
Inventory	(2,368)	(4,271)
Accounts payable	(924)	(2,770)
Accrued expenses and other current liabilities	(1,763)	9,630
Lease liabilities and other long-term liabilities	(1,295)	(1,175)
Net cash used in operating activities	(90,694)	(92,720)
Cash flows from investing activities:
Purchases of property and equipment and other assets	(1,942)	(1,335)
Purchases of short-term investments	(113,592)
Proceeds from sales or maturities of short-term investments	37,325
Net cash used in investing activities	(78,209)	(1,335)
Cash flows from financing activities:
Proceeds from common stock offerings, net of offering costs	158,557	8,425
Payment of principal on finance lease	(32)	(30)
Proceeds from exercise of stock options and issuance of common stock under employee stock purchase plan	2,103	587
Net cash provided by financing activities	160,628	8,982
Net decrease in cash, cash equivalents and restricted cash:	(8,275)	(85,073)
Cash, cash equivalents and restricted cash at beginning of period	98,031	183,104
Cash, cash equivalents and restricted cash at end of period	89,756	98,031
Reconciliation of cash, cash equivalents and restricted cash:
Cash, cash equivalents, and restricted cash at end of period	89,756	183,104
Cash and cash equivalents at end of period	77,264	85,449
Non-cash investing and financing activities:
Right-of-use asset obtained in exchange for finance lease obligation		136
Purchases of property and equipment in accounts payable	130	195
Supplemental disclosure:
Cash paid for interest	$ 7,528	7,522
Right-of-use assets obtained in exchange of operating lease obligations		$ 1,852

Nature of business

Nature of business	12 Months Ended
	Dec. 31, 2020
Nature of business
Nature of business	Note 1: Nature of business Nature of Business — Kala Pharmaceuticals, Inc. (the “Company”) was incorporated on July 7, 2009, and is a biopharmaceutical company focused on the discovery, development and commercialization of innovative therapies for diseases of the eye. The Company has applied its AMPPLIFY ® mucus-penetrating particle (“MPP”) Drug Delivery Technology to loteprednol etabonate (“LE”), a corticosteroid designed for ocular applications, resulting in the U.S. Food and Drug Administration’s (the “FDA”) approval of EYSUVIS TM (loteprednol etabonate ophthalmic suspension) 0.25%, for the short-term (up to two weeks) treatment of the signs and symptoms of dry eye disease, and INVELTYS ® (loteprednol etabonate ophthalmic suspension) 1% as the first and only topical twice-daily ocular corticosteroid for treatment of post-operative inflammation and pain following ocular surgery . In January 2019, the Company launched its first commercial product, INVELTYS, in the United States and began shipping its second commercial product, EYSUVIS, to wholesalers in the United States in late December 2020 with the full promotional launch commencing in early January 2021. The Company is engaged in the commercialization of EYSUVIS and INVELTYS, research and development activities, raising capital and recruiting skilled personnel. The Company is subject to a number of risks similar to those of other companies conducting high-risk, research and development of pharmaceutical product candidates and launching products for the first time. Principal among these risks are dependence on key individuals and intellectual property, competition from other products and companies and the technical risks associated with the successful research, development and marketing of its product candidates. The Company’s success is dependent upon its ability to successfully commercialize its products, the success of its research and development efforts, its ability to obtain regulatory approval of its product candidates, its ability to raise additional capital when needed and, ultimately, attain profitable operations. The Company is also progressing its pipeline of proprietary preclinical development programs targeted to address front and back of the eye diseases. These preclinical development programs, all of which are new chemical entities, include its receptor Tyrosine Kinase Inhibitor program, that is designed to inhibit the vascular endothelial growth factor pathway, for the treatment of retinal diseases, including wet age-related macular degeneration; its selective glucocorticoid receptor modulators, which are a novel class of therapies designed to modify the downstream activity of the receptors to exhibit the anti-inflammatory and immunomodulatory properties of the corticosteroid class of therapies without their associated side effects; and its novel surface targeting steroid designed to target the ocular surface and thus have the potential to have fewer side effects compared to traditional topical steroids. The Company owns all intellectual property and worldwide rights to these pipeline preclinical development programs. Recent Financings In addition, the underwriters were granted an overallotment option to purchase an additional 1,125,000 shares of the common stock at the same public offering price, less underwriting discounts and commissions (the “Overallotment Shares”). On October 11, 2018, the underwriters exercised in full their option to purchase the Overallotment Shares. The total number of Shares and Overallotment Shares sold by the Company in the offering was 8,625,000 shares, resulting in net proceeds to the Company, after underwriting discounts and offering expenses, of approximately $66,132 . In connection with the filing of the Shelf Registration, the Company entered into a sales agreement with Jefferies, LLC (the “2018 Sales Agreement”) pursuant to which the Company may issue and sell, from time to time, up to an aggregate of $50,000 of its common stock in an at-the-market equity offering (“ATM Offering”) through Jefferies, LLC, as sales agent. As of December 31, 2019, the Company issued 2,592,934 shares of its common stock under the ATM Offering, resulting in net proceeds to the Company of $13,059. During the first quarter of 2020, the Company issued an aggregate of 2,352,671 shares of its common stock under the ATM Offering, resulting in net proceeds to the Company of $12,546 . On March 10, 2020, the Company notified Jefferies that it was suspending and terminating the prospectus related to the 2018 Sales Agreement. ​ On March 11, 2020, the Company sold 16,000,000 shares of its common stock in an underwritten offering (the “2020 Offering”), pursuant to the 2018 Shelf Registration, at a public offering price of $7.89 per share, resulting in net proceeds of $118,207 , after underwriting discounts, commissions, and offering expenses. In addition, the underwriters of the 2020 Offering were granted the option for a period of 30 days to purchase up to an additional 2,400,000 shares of common stock offered in the public offering at the public offering price, less underwriting discounts, commissions and offering expenses. On April 3, 2020, the underwriters exercised their option and purchased an additional 979,371 shares of common stock at $7.89 per share, resulting in net proceeds to the Company of $7,216 , after underwriting discounts, commissions, and offering expenses. The total number of shares sold by the Company in the 2020 Offering was 16,979,371 , resulting in total net proceeds to the Company, after underwriting discounts, commissions, and offering expenses, of $125,423 . On May 7, 2020, the Company filed a shelf registration statement on Form S-3 with the SEC, which was declared effective on May 19, 2020, (the “2020 Shelf Registration”). Under the 2020 Shelf Registration, the Company may offer and sell up to $350,000 of a variety of securities including common stock, preferred stock, warrants, depositary shares, debt securities or units during the three-year period that commenced upon the 2020 Shelf Registration becoming effective. In connection with the filing of the 2020 Shelf Registration, the Company entered into an amended and restated sales agreement with Jefferies pursuant to which it may issue and sell, from time to time, up to an aggregate of $75,000 of its common stock under its ATM Offering through Jefferies, as a sales agent. During the fourth quarter of 2020, the Company issued an aggregate of 2,821,059 shares of its common stock under the ATM Offering, resulting in net proceeds of $20,612. As of December 31, 2020, there was approximately $53,751 of shares of common stock remaining under the ATM Offering that the Company may issue and sell in the future and, excluding the funds designated to be offered under its ATM Offering, there was approximately $275,000 of securities available to be issued under the 2020 Shelf Registration. In January 2021, the Company issued and sold an additional 2,552,457 shares of its common stock under its ATM Offering, resulting in net proceeds of $18,226. As of the date of this Annual Report on Form 10-K, there was $35,000 of shares of common stock remaining under the ATM Offering that we may issue and sell in the future. On October 1, 2018, the Company entered into a credit agreement (the “Athyrium Credit Facility”), with Athyrium Opportunities III Acquisition LP (“Athyrium”). The Athyrium Credit Facility provides for a Term Loan A in the aggregate principal amount of $75,000 (the “Athyrium Term Loan A”), and a Term Loan B in the aggregate principal amount of $35,000 (the “Athyrium Term Loan B”). On October 1, 2018, the Company borrowed the entire principal amount of the Athyrium Term A Loan. The Company did not satisfy the conditions to draw down any of the Term Loan B funds, and as a result, the Term Loan B funds are no longer available. COVID-19 – The ongoing novel coronavirus pandemic, commonly referred to as COVID-19, which began in December 2019 and was declared a global pandemic by the World Health Organization on March 11, 2020, has spread worldwide, causing federal, state and local governments to implement measures to slow the spread of the pandemic through quarantines, strict travel restrictions and bans, heightened border scrutiny and other measures. In order to safeguard the health of its employees, the Company is following, and will continue to follow, recommendations from the U.S. Centers for Disease Control and Prevention, as well as federal, state and local governments, regarding working-from-home practices for non-essential employees. As a result, all office-based personnel have been instructed to work from home, and the Company’s laboratory facilities, that support its early-stage research activities, are being utilized as necessary. In addition, the Company previously suspended its sales force from substantially all in-person interactions with physicians and customers and was limited to conducting educational and promotional activities virtually. However, the Company’s sales force has resumed substantially all in-person interactions in the field. If it suspends all or some in-person interactions limited to conducting educational and promotional activities virtually, which has hampered, and may continue to hamper, its ability to market INVELTYS. The effects of COVID-19 may also disrupt the full promotional launch and commercialization of EYSUVIS. In addition, moratoria on elective ocular surgeries in many jurisdictions, INVELTYS, which is indicated for the treatment of post-operative inflammation and pain following ocular surgery. The extent of the impact of COVID-19 on the Company’s commercialization efforts of EYSUVIS and INVELTYS and its operational and financial performance will depend on certain developments, including the length and severity of this pandemic and the impact on its customers, employees, vendors, and government agencies, all of which are uncertain and cannot be predicted. The Company cannot reasonably estimate the extent to which the disruption may materially impact its consolidated results of operations or financial position.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2: Summary of Significant Accounting Policies Principles of Consolidation— Basis of Presentation The Company expects that its cash, cash equivalents and short-term investments as of December 31, 2020, together with anticipated net revenue from sales of INVELTYS, will enable it to fund its operating expenses, debt service obligations and capital expenditure requirements for at least 12 months from the date these consolidated financial statements were issued. This evaluation is based on relevant conditions and events that are known and reasonably knowable at the date that the consolidated financial statements are issued. As a result, the Company could deplete its available capital resources sooner than it currently expects. Use of Estimates— Product Revenues, Net The Company accounts for revenue in accordance with Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers Performance Obligations The Company determined that performance obligations are satisfied and revenue is recognized when a customer takes control of the Company’s products, which occurs at a point in time. This generally occurs upon delivery of the products to customers, at which point the Company recognizes revenue and records accounts receivable. Payment is typically received 70 to 90 days after satisfaction of the Company’s performance obligations. Transaction Price and Variable Consideration Revenue is measured as the amount of consideration the Company expects to receive in exchange for transferring products to a customer (“transaction price”). The transaction price for product sales includes variable consideration related to chargebacks, rebates, sales incentives and allowances, distribution service fees, and returns. The Company will estimate the amount of variable consideration that should be included in the transaction price. These estimates take into consideration a range of possible outcomes that are probability-weighted for relevant factors such as the Company’s historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. These provisions reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained and is included in net sales only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. In general, performance obligations do not include any estimated amounts of variable consideration that are constrained. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. The following table summarizes activity in each of the Company’s product revenue provision and allowance categories for the years ended December 31, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trade Discounts, ​ ​ ​ ​ ​ ​ ​ ​ Allowances and ​ ​ ​ ​ Rebates and ​ ​ Chargebacks (1) Product Returns (2) Incentives (3) Balance as of January 1, 2019 ​ $ — ​ $ — ​ $ — Provision related to current period sales ​ ​ 4,031 ​ ​ 321 ​ ​ 24,812 Credit/payments made ​ ​ (2,248) ​ ​ (141) ​ ​ (14,768) Balance as of December 31, 2019 ​ $ 1,783 ​ $ 180 ​ $ 10,044 Provision related to current period sales ​ ​ 3,937 ​ ​ 207 ​ ​ 23,265 Changes in estimate related to prior period sales ​ ​ 21 ​ ​ 213 ​ ​ 74 Credit/payments made ​ ​ (4,584) ​ ​ — ​ ​ (28,479) Balance as of December 31, 2020 ​ $ 1,157 ​ $ 600 ​ $ 4,904 (1) Trade discounts, allowances and chargebacks include fees for distribution service fees, prompt pay and other discounts, and chargebacks. Trade discounts, allowances and chargebacks are deducted from gross revenue at the time revenues are recognized and are recorded as a reduction to accounts receivable on the Company’s consolidated balance sheets. (2) Provisions for product returns are deducted from gross revenues at the time revenues are recognized and are included in accrued expenses and other current liabilities on the Company’s consolidated balance sheets. (3) Rebates and incentives include managed care rebates, government rebates, co-pay program incentives, and sales incentives and allowances. Provisions for rebates and discounts are deducted from gross revenues at the time revenues are recognized and are included in accrued expenses and other current liabilities on the Company’s consolidated balance sheets. As of December 31, 2020 and 2019, the Company did not have any transaction price allocated to remaining performance obligations and any costs to obtain contracts with customers, including pre-contract costs and set up costs, were immaterial. Accounts Receivable, net The Company recorded no allowance for doubtful accounts as of December 31, 2020 or December 31, 2019. The Company recorded an allowance of $1,157 and $1,783 for expected sales discounts, related to prompt pay discounts and other discounts, contractual fee for service arrangements and chargebacks, to wholesalers and distributors as of December 31, 2020 and December 31, 2019, respectively. Cost of Product Revenues— Cash and Concentration of Credit Risk Three Customers comprised 10% or more of the Company’s accounts receivable balance as of December 31, 2020 and 2019. These Customers comprised 39%, 33% and 25% of the accounts receivable balance, respectively, as of December 31, 2020 and 41%, 35% and 23% of the accounts receivable balance, respectively, as of December 31, 2019. To date, the Company has not experienced any losses with respect to the collection of its accounts receivable and believes that its entire accounts receivable balances is collectible as of December 31, 2020. The same three Customers comprised 10% or more of the Company’s revenue during the years ended December 31, 2020 and 2019. These Customers comprised 40%, 29% and 28% of revenue, respectively, during the year ended December 31, 2020 and 39%, 33% and 26% of revenue, respectively, during the year ended December 31, 2019. The Company has no financial instruments with off-balance sheet risk of loss. Cash Equivalents Restricted Cash Investments— Available-for-sale investments are recorded at fair value, with unrealized gains or losses included in comprehensive loss on the consolidated statements of operations and comprehensive loss and in accumulated other comprehensive income or loss on the consolidated balance sheets. Realized gains and losses, interest income earned on the Company’s cash, cash equivalents and investments, and amortization or accretion of discounts and premiums on investments are included within other income (expense). ​ The Company reviews investments for other-than-temporary impairment whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. The Company did not record any such impairments during the year ended December 31, 2020. ​ Inventory ​ Inventory produced that will be used in a promotional sample program is expensed to selling, general and administrative expense when it is designated as a sample. Long-term inventory includes raw materials, work-in-progress and/or finished goods inventory with an anticipated consumption or sale beyond one year based on the Company’s forecasted expectations. ​ Leases ​ The components of a lease should be split into three categories: lease components (e.g., land, building, etc.), non-lease components (e.g., common area maintenance, maintenance, consumables, etc.), and non-components (e.g., property taxes, insurance, etc.). Then the fixed and in-substance fixed contract consideration (including any related to non-components) must be allocated based on fair values to the lease components and non-lease components. Although separation of lease and non-lease components is required, certain practical expedients are available to entities. Entities electing the practical expedient would not separate lease and non-lease components. Rather, they would account for each lease component and the related non-lease component together as a single component. The Company’s facilities operating leases have lease and non-lease components which the Company has elected to use the practical expedient and account for each lease component and related non-lease component as one single component. The lease component results in a right-of-use asset being recorded on the consolidated balance sheets and amortized as lease expense on a straight-line basis to the consolidated statements of operations and comprehensive loss. Property and Equipment, net Laboratory equipment office and three Patent Costs Impairment of Long-Lived Assets Segment Information Research and Development Costs Accrued Expenses Stock-Based Compensation The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. The assumptions used in calculating the fair value of stock-based payment awards represent management’s best estimates. The Company lacks sufficient company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and will continue to do so until it has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. 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 on common stock and does not expect to pay any cash dividends in the foreseeable future. The fair value of restricted stock units (“RSUs”) and performance stock units (“PSUs”) are equal to the closing sale price of the Company’s common stock on the date of grant. Income Taxes The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions and other issues. The Company may recognize the tax benefit from an uncertain tax position only if it is more likely than not that the position will be sustained on examination by the taxing authorities based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such a position is measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. As a result, reserves are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized following resolution of any potential contingencies present. Net Loss per Share and the issuance of unvested RSUs and PSUs The weighted average number of common shares included in the computation of diluted net loss gives effect to all potentially dilutive common equivalent shares, including outstanding stock options, warrants and unvested RSUs and PSUs As of December 31, 2020 and 2019, potentially dilutive securities excluded from the calculation of diluted net loss per share because including such securities would have an anti-dilutive effect consisted of outstanding options to purchase 8,745,127 and 7,453,076 shares of the Company’s common stock, respectively, an aggregate of 942,222 unvested RSUs and PSUs as of December 31, 2020 and an aggregate of 248,505 and 384,163 unexercised warrants as of December 31, 2020 and 2019, respectively. Recent Accounting Pronouncements In August 2018, the Financial Accounting Standards Board (“ Accounting Standards Update (“ Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measuremen In August 2018, the FASB issued ASU 2018-15 , Intangibles – Goodwill and Other – Internal-Use Software -Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 significantly changes the impairment model for most financial assets and certain other instruments. ASU 2016-13 will require immediate recognition of estimated credit losses expected to occur over the remaining life of many financial assets, which will generally result in earlier recognition of allowances for credit losses on loans and other financial instruments. In November 2019, the FASB issued ASU 2019-10, Financial Instruments – Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842) (“ASU 2019-10”) , which is effective for public business entities that meet the definition of an SEC filer, excluding entities eligible to be Smaller Reporting Companies (“SRCs”) as defined by the SEC, for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years and for all other entities, including SRCs, for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. Upon adoption, beginning January 1, 2023, the Company does not expect ASU 2019-10 to have a material effect on its consolidated financial statements.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2020
Fair Value of Financial Instruments
Fair Value of Financial Instruments	Note 3: Fair Value of Financial Instruments The Company has short-term investments which are considered financial instruments that are measured on a recurring basis. ASC 820, Fair Value Measurements and Disclosures ● 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 financial instruments consist primarily of cash equivalents and short-term investments in money market funds and short-term securities. Cash equivalents and short-term investments are reported at their respective fair values on the Company’s consolidated balance sheets. See Note 4, “Investments” for additional information. The following table sets forth the fair value of the Company’s financial assets by level within the fair value hierarchy as of December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ Fair Value ​ Level 1 ​ Level 2 ​ Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 63,811 ​ $ 63,811 ​ $ — ​ $ — Short-term investments ​ ​ 76,276 ​ ​ 76,276 ​ ​ — ​ ​ — Total Assets ​ $ 140,087 ​ $ 140,087 ​ $ — ​ $ — ​ During the year ended December 31, 2020 there were no transfers between 1 2 The carrying value reported on the accompanying consolidated balance sheets of cash, restricted cash, accounts receivable, accounts payable and accrued expenses approximate their fair value due to their short-term nature. Management believes that the Company’s long-term debt (see Note 10) bears interest at the prevailing market rate for instruments with similar characteristics and, accordingly, the carrying value of long-term debt, also approximates its fair value. The fair value of the outstanding debt was estimated using a discounted cash flow analysis based on current market interest rates for debt issuances with similar remaining years to maturity, adjusted for credit risk, which represents a Level 3 measurement.

Investments

Investments	12 Months Ended
	Dec. 31, 2020
Investments
Investments	Note 4: Investments Investments by security type consisted of the following as of December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ ​ Gross ​ Gross ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost ​ Gains ​ Losses ​ Value U.S. treasury securities $ 26,744 ​ $ 2 ​ $ — ​ $ 26,746 U.S. government agencies securities ​ 49,528 ​ ​ 2 ​ ​ — ​ ​ 49,530 Total $ 76,272 ​ $ 4 ​ $ — ​ $ 76,276 ​ As of December 31, 2020, all of the Company’s investments had a contractual maturity within one year. The fair value of all of the Company’s investments are classified as short-term on its consolidated balance sheets. The Company did not have any investment securities as of December 31, 2019.

Inventory

Inventory	12 Months Ended
	Dec. 31, 2020
Inventory
Inventory	Note 5: Inventory Inventory consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ Raw materials ​ $ 801 ​ $ 1,387 Work in progress ​ ​ 6,437 ​ ​ 4,166 Finished goods ​ ​ 4,210 ​ ​ 2,873 Total inventory ​ $ 11,448 ​ $ 8,426 ​ ​ As of December 31, 2020, the Company had $5,229 of current inventory and $6,219 of long-term inventory. As of December 31, 2019, the Company had $4,648 of current inventory and $3,778 of long-term inventory.

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	12 Months Ended
	Dec. 31, 2020
Prepaid Expenses and Other Current Assets
Prepaid Expenses and Other Current Assets	Note 6: Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets, consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ Insurance ​ $ 1,201 ​ $ 906 Deposits ​ ​ 606 ​ ​ 699 Non-trade receivables ​ ​ 250 ​ ​ 1,535 Other ​ ​ 949 ​ ​ 684 Prepaid expenses and other current assets ​ $ 3,006 ​ $ 3,824 ​

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2020
Property and Equipment, Net
Property and Equipment, Net	Note 7: Property and Equipment, Net Property and equipment, net, consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ Equipment ​ $ 2,652 ​ $ 2,627 Furniture and office equipment ​ ​ 1,144 ​ ​ 1,144 Computer hardware and software ​ ​ 1,108 ​ ​ 892 Leasehold improvements ​ ​ 356 ​ ​ 356 Construction in progress ​ ​ 1,330 ​ ​ 195 Property and equipment — ​ ​ 6,590 ​ ​ 5,214 Less: Accumulated depreciation ​ ​ (3,424) ​ ​ (2,516) Property and equipment—net ​ $ 3,166 ​ $ 2,698 ​ Depreciation expense for the years ended December 31, 2020 and 2019 was $908 and $843, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2020
Accrued Expenses
Accrued Expenses	Note 8: Accrued Expenses Accrued expenses consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ Compensation and benefits ​ $ 9,676 ​ $ 6,502 Accrued revenue reserves (1) ​ ​ 5,224 ​ ​ 9,482 Commercial costs ​ ​ 2,103 ​ ​ 930 Professional services ​ ​ 926 ​ ​ 760 Contract manufacturing ​ ​ 336 ​ ​ 630 Development costs ​ ​ 154 ​ ​ 1,600 Other ​ ​ 552 ​ ​ 1,025 Accrued expenses ​ $ 18,971 ​ $ 20,929 (1) As of December 31, 2020 and 2019, $280 and $742 of additional revenue reserves were in accounts payable, respectively.

Debt

Debt	12 Months Ended
	Dec. 31, 2020
Debt
Debt	Note 10: Debt On October 1, 2018, the Company entered into a credit agreement (the “Athyrium Credit Facility”) with Athyrium Opportunities III Acquisition LP (“Athyrium”) for up to $110,000. The Athyrium Credit Facility provided for a Term Loan A in the aggregate principal amount of $75,000 (the “Term Loan A”), and a Term Loan B in the aggregate principal amount of $35,000 (the “Term Loan B”). On October 1, 2018, the Company borrowed the entire principal amount of the Term Loan A. The Company did not satisfy the conditions to draw down any of the Term Loan B funds, and as a result, the Term Loan B funds are no longer available. The maturity date of the Athyrium Credit Facility is October 1, 2024, the six-year anniversary of the close. The Term Loan A bears interest at a rate of 9.875% per annum, with quarterly, interest-only payments until the fourth anniversary of the Term Loan A. The unpaid principal amount of the Term Loan A is due and payable in quarterly installments starting on October 1, 2022. The Company may make voluntary prepayments, in whole or in part, and subject to certain exceptions, is required to make mandatory prepayments upon the occurrence of certain events of default as defined in the agreement, including but not limited to, the occurrence of a change of control. In addition, upon payment or repayment of any outstanding balance under the Athyrium Credit Facility, the Company will have to pay a 1% exit fee of the total principal payments (whether mandatory, voluntary, or at maturity) made throughout the term. The exit fee of $750 based on the $75,000 principal amount outstanding, will be accreted to the carrying amount of the debt using the effective interest method over the term of the loan. All mandatory and voluntary prepayments of the Athyrium Credit Facility are subject to the payment of prepayment premiums as follows: (i) if prepayment occurs prior to the second anniversary of the applicable date of issuance, an amount equal to the amount by which (a) the present value of 105% of the principal prepaid plus all interest that would have accrued on such principal through such second anniversary exceeds (b) the amount of principal prepaid, (ii) if prepayment occurs on or after the second anniversary of the applicable date of issuance but prior to the third anniversary of such issuance, an amount equal to 3% of the principal prepaid, and (iii) if prepayment occurs on or after the third anniversary of the applicable date of issuance but prior to the fourth anniversary of such issuance, an amount equal to 2% of the principal prepaid. No prepayment premium is due on any principal prepaid after the fourth anniversary of the applicable date of issuance. The Athyrium Credit Facility includes features requiring (1) additional interest rate upon an event of default accrued at an additional 3% , or a total interest rate of 12.875% , and (2) the lender’s right to declare all outstanding principal and interest immediately payable upon an event of default. These two features were analyzed and determined to be embedded derivatives to be valued as separate financial instruments. These embedded derivatives were bundled and valued as one compound derivative in accordance with the applicable accounting guidance for derivatives and hedging transactions. The Company determined that, due to the unlikely event of default, the embedded derivatives have a de minimis value as of December 31, 2020. The derivative liability will be remeasured at fair value at each reporting date, with changes in fair value being recorded as other income (expense) in the consolidated statements of operations . The Athyrium Credit Facility is secured by a pledge of substantially all of the Company’s assets and contains affirmative and negative covenants customary for financings of this type, including limitations on the Company’s and its subsidiaries’ ability to, among other things, incur and prepay additional debt, grant or permit additional liens, make investments and acquisitions, merge or consolidate with others, dispose of assets, change in the nature of business, enter into sale and leaseback transactions, make distributions, and enter into affiliate transactions, in each case, subject to certain exceptions. In addition, the Athyrium Credit Facility also contains a financial covenant requiring the Company to maintain at least $10,000 of cash and cash equivalents. As a result of this financial covenant, the Company has recorded $10,000 as restricted cash as of December 31, 2020 and December 31, 2019. As of December 31, 2020, the Company was in compliance with the covenants. In connection with the Athyrium Credit Facility, the Company issued a warrant (“Warrant”), to purchase up to 270,835 shares of the Company’s common stock, at an exercise price per share of $12.18456 . The Warrant is immediately exercisable as to 184,660 shares. The remaining 86,175 shares under the Warrant were exercisable only upon the Company’s draw of the Term Loan B and, as a result, the remaining 86,175 shares under the Warrant are no longer exercisable. In addition, the Company paid certain fees to Athyrium and other third-party service providers. These fees paid to Athyrium were recorded as a debt discount while the fees paid to other third-party service providers were recorded as debt issuance cost. These costs, along with the fair value of the Warrant of $1,900 are being amortized using the effective interest method over the term of the Athyrium Credit Facility. The amortization of debt discount and debt issuance cost is included in interest expense within the consolidated statements of operations and comprehensive loss. As of December 31, 2020, the effective interest rate was 11.63%, which takes into consideration the non-cash accretion of the exit fee and the amortization of the debt discount and issuance costs. During the year ended December 31, 2020, the Company recognized interest expense of $8,440 which consisted of amortization of the debt discount of $910, and the contractual coupon interest expense of $7,530. During the year ended December 31, 2019, the Company recognized interest expense of $8,316, which consisted of amortization of the debt discount of $807, and the contractual coupon interest expense of $7,509. The components of the carrying value of the debt as of December 31, 2020 and December 31, 2019 are detailed below: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 Principal loan balance ​ $ 75,000 ​ $ 75,000 Unamortized debt discount and issuance cost ​ ​ (3,088) ​ ​ (3,999) Cumulative accretion of exit fee ​ ​ 331 ​ ​ 183 Long-term debt, net ​ $ 72,243 ​ $ 71,184 ​ The annual principal payments due under the Athyrium Credit Facility as of December 31, 2020 were as follows: ​ ​ ​ ​ Years Ending December 31, ​ ​ 2021 ​ $ — 2022 ​ ​ 16,665 2023 ​ ​ 33,330 2024 ​ ​ 25,005 Total ​ $ 75,000 ​

Warrants

Warrants	12 Months Ended
	Dec. 31, 2020
Warrants
Warrants	Note 11: Warrants The Company has issued warrants in connection with debt transactions that were completed prior to 2017. In connection with and in consideration for the commitment of the Athyrium Credit Facility, on October 1, 2018, the Company issued to Athyrium the Warrant as described in Note 10. The following table summarizes the common stock warrants outstanding as of December 31, 2020 and December 31, 2019, each exercisable into the number of shares of common stock set forth below as of the specified dates: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Exercisable at ​ ​ Exercise Expiration Exercisable December 31, December 31, Issued Price ​ Date ​ From ​ 2020 ​ 2019 2013 ​ $ 7.50 ​ April 2021 ​ July 2017 ​ 33,333 ​ 82,816 2014 ​ $ 7.50 November 2024 July 2017 ​ 16,000 ​ 16,000 2016 ​ $ 8.27 October 2026 September 2017 ​ 14,512 ​ 14,512 2018 ​ $ 12.18 ​ October 2025 ​ October 2018 ​ 184,660 ​ 184,660 ​ ​ ​ ​ ​ ​ ​ ​ ​ 248,505 ​ 297,988 ​

Common and Preferred Stock

Common and Preferred Stock	12 Months Ended
	Dec. 31, 2020
Common and Preferred Stock
Common and Preferred Stock	Note 12: Common and Preferred Stock Preferred Stock The Company was authorized to issue up to 5,000,000 shares of preferred stock as of December 31, 2020 and 2019. There was no preferred stock outstanding as of December 31, 2020 and 2019. Common Stock The Company was authorized to issue up to 120,000,000 shares of common stock with a $0.001 par value per share as of December 31, 2020 and 2019. The Company had 58,915,375 and 36,086,254 shares of common stock issued and outstanding as of December 31, 2020 2019 Holders of the Company’s common stock are entitled to one vote for each share held on all matters submitted to a vote of stockholders and do not have cumulative voting rights. Each election of directors by the Company’s stockholders will be determined by a plurality of the votes cast by the stockholders entitled to vote on the election. Holders of common stock are entitled to receive proportionately any dividends as may be declared by the Company’s Board of Directors (the “Board”), subject to any preferential dividend rights of outstanding preferred stock that it may issue in the future. In the event of the Company’s liquidation or dissolution, the holders of its common stock are entitled to receive proportionately all assets available for distribution to stockholders after the payment of all debts and other liabilities and subject to the prior rights of any of its outstanding preferred stock. Holders of the Company’s common stock have no preemptive, subscription, redemption or conversion rights. The rights, preferences and privileges of holders of the Company’s common stock are subject to and may be adversely affected by the rights of the holders of shares of any series of its preferred stock that it may designate and issue in the future. Voting, dividend and liquidation rights of the holders of the common stock are subject to and qualified by the rights, powers and preferences of the holders of preferred stock that the Company may issue in the future. Voting Each holder of outstanding shares of common stock shall be entitled to one vote in respect of each share. The holders of outstanding shares of common stock, voting together as a single class, shall be entitled to elect one director. The number of authorized shares of common stock may be increased or decreased by the affirmative vote of a majority of the outstanding shares of common stock and preferred stock voting together as a single class. Dividends Subject to the payment in full of all preferential dividends to which the holders of preferred stock may be entitled, the holders of common stock shall be entitled to receive dividends out of funds legally available therefor at such times and in such amounts as the Board may determine in its sole discretion, with holders of preferred stock and common stock sharing pari passu in such dividends. Liquidation Rights Upon any liquidation, after the payment or provision for payment of all debts and liabilities of the Company and all preferential amounts to which the holders of preferred stock may be entitled with respect to the distribution of assets in liquidation, the holders of common stock shall be entitled to share ratably in the remaining assets of the Company available for distribution. Reserved Shares As of December 31, 2020 and 2019, the Company has reserved shares of common stock for issuance upon exercise of rights under warrants, under the Amended and Restated 2017 Employee Stock Purchase Plan (as amended, the “ESPP”), upon the exercise of stock options and upon the vesting of RSUs and PSUs as follows (see Note 13): ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 Warrant rights to acquire common stock ​ 248,505 ​ 384,163 ESPP ​ 484,772 ​ 438,307 Outstanding inducement stock option awards ​ 945,842 ​ 705,500 2009 Plan ​ 2,251,570 ​ 2,530,586 2017 Plan ​ 7,813,784 ​ 4,429,849 Total ​ 11,744,473 ​ 8,488,405 ​

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2020
Stock-based Compensation
Stock-based Compensation	Note 13: Stock-based Compensation Stock Incentive Plans In December 2009, the Board adopted the 2009 Employee, Director and Consultant Equity Incentive Plan (the “2009 Plan”) for the issuance of common stock and stock options to employees, officers, directors, consultants, and advisors. Upon the closing of the Company’s IPO, no further awards will be made under the 2009 Plan. In July 2017, the Company’s 2017 Equity Incentive Plan (the “2017 Plan”) became effective. The 2017 Plan was established to provide equity-based ownership opportunities for employees, officers, directors, consultants, and advisors. On June 25, 2020, the 2017 Plan was amended to increase the number of shares of common stock authorized for issuance thereunder by 2,000,000 shares. As of December 31, 2020, there were 1,323,847 shares of common stock available for grant under the 2017 Plan. In addition, any shares of common stock subject to awards under the 2009 Plan that expire, are forfeited, or are otherwise surrendered, without having been fully exercised or resulting in any common stock being issued will become available for issuance under the 2017 Plan, up to an additional 2,251,570 shares, which is the number of shares issuable pursuant to outstanding awards granted under the 2009 Plan. Also approved under the 2017 Plan is an annual increase for each of the years through December 31, 2027, equal to the least of (i) 3,573,766 shares of common stock, (ii) 4% of the shares of common stock outstanding on December 31 of the prior year and (iii) an amount determined by the Board. Under the plans, the Board determines the number of shares of common stock to be granted pursuant to the awards, as well as the exercise price and terms of such awards. The exercise price of incentive stock options cannot be less than the fair value of the common stock on the date of grant. Stock options awarded under the plans expire 10 years after the grant date, unless the Board sets a shorter term. Options granted under the plans generally vest over a four-year period. A portion of the unvested stock options will vest upon the sale of all or substantially all of the stock or assets of the Company. Inducement Stock Option Awards During the years ended December 31, 2020 and December 31, 2019, the Company granted non-statutory stock options to purchase an aggregate of 350,800 shares and 207,500 shares of the Company’s common stock, respectively, to new employees. These stock options will vest over a four-year period, with 25% of the shares underlying each option award vesting on the one-year anniversary of the applicable employees’ new hire date and the remaining 75% of the shares underlying each option award vesting monthly thereafter for three-years . Vesting of each option award is subject to such employee’s continued service with the Company through the applicable vesting dates. These stock options were granted outside of the 2017 Plan as an inducement material to each employee’s acceptance of employment with the Company in accordance with Nasdaq Listing Rule 5635(c)(4). A summary of option activity for employee awards under the 2009 Plan, the 2017 Plan and inducement grants for the year ended December 31, 2020 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ Weighted ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Number of ​ Exercise ​ Contractual ​ Intrinsic ​ Shares Price Term Value ​ ​ ​ ​ ​ ​ (Years) ​ (in thousands) Outstanding as of January 1, 2020 ​ 7,453,076 ​ $ 7.46 ​ 7.7 ​ $ 1,313 Granted ​ 1,816,222 ​ ​ 4.63 ​ ​ ​ ​ ​ Exercised ​ (345,479) ​ ​ 3.15 ​ ​ ​ ​ ​ Forfeited ​ (178,692) ​ ​ 8.30 ​ ​ ​ ​ ​ Outstanding as of December 31, 2020 ​ 8,745,127 ​ $ 7.03 ​ 7.3 ​ $ 16,275 Vested or expected to vest as of December 31, 2020 ​ 8,745,127 ​ $ 7.03 ​ 7.3 ​ $ 16,275 Options exercisable as of December 31, 2020 ​ 5,362,040 ​ $ 7.45 ​ 6.5 ​ $ 10,235 ​ The Company records stock-based compensation related to stock options granted at fair value. The Company utilizes the Black-Scholes option-pricing model to estimate the fair value of stock option grants and to determine the related compensation expense. The assumptions used in calculating the fair value of stock-based payment awards represent management’s best estimates. The assumptions used in determining fair value of the stock options granted during the years ended December 31, 2020 and 2019 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 Expected volatility 79.6% – 82.5% ​ 80.7% – 83.7% Risk-free interest rate 0.37% – 1.73% ​ 1.44% – 2.58% Expected dividend yield ​ 0% ​ ​ ​ 0% ​ Expected term (in years) 5.91 – 6.08 ​ 5.27 – 6.63 ​ The Company derived the risk-free interest rate assumption from the U.S. Treasury rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the awards being valued. The Company based the expected dividend yield on its expectation of not paying dividends in the foreseeable future. The Company calculated the expected term of options using the simplified method, as the Company lacks relevant historical data due to the Company’s limited operating experience. The expected volatility is based upon the historical volatility of comparable companies with publicly available share prices. The impact of forfeitures on compensation expense is recorded as they occur. The weighted average grant-date fair value of options granted during the years ended December 31, 2020 and 2019, was $3.20 and $3.45, respectively. The fair value is being expensed over the vesting period of the options on a straight-line basis as the services are being provided. As of December 31, 2020 and 2019, there was $15,753 and $19,201, respectively, of unrecognized compensation cost related to the stock options granted, which is expected to be expensed over a weighted-average period of 2.35 years and 2.31 years, respectively. Stock-based compensation expense was classified in the consolidated statements of operations and comprehensive loss as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ Cost of product revenues ​ $ 92 ​ $ 268 Research and development ​ ​ 3,083 ​ ​ 2,844 Selling, general and administrative ​ ​ 10,137 ​ ​ 6,879 Total ​ $ 13,312 ​ $ 9,991 ​ Stock-based compensation costs capitalized into inventory totaled $888 and $59 for the years ended December 31, 2020 and 2019, respectively. Capitalized stock-based compensation is recognized as an expense in cost of product revenues when the related product is sold or in selling, general and administrative expense when the related product is designated as a sample. The Company received cash proceeds from the exercise of stock options of $1,087 and $42 during the years ended December 31, 2020 and 2019, respectively. The total intrinsic value of options exercised for the year ended December 31, 2020 and 2019, was $2,124 and $98, respectively. Restricted Stock Units and Performance-Based Restricted Stock Units A summary of activity for RSUs and PSUs for the year ended December 31, 2020 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average ​ ​ ​ ​ ​ Grant Date ​ ​ Shares ​ ​ Fair Value Unvested and outstanding balance as of January 1, 2020 ​ — ​ $ — Changes during the period: ​ ​ ​ ​ ​ RSUs granted ​ 263,560 ​ ​ 11.70 PSUs granted ​ 693,537 ​ ​ 11.70 PSUs forfeited ​ (14,875) ​ ​ 11.70 Unvested and outstanding balance as of December 31, 2020 ​ 942,222 ​ $ 11.70 ​ Employee Stock Purchase Plan The ESPP provides for two six-month offering periods each year; the first offering period begins on the first trading day on or after each January 1; the second offering period begins on the first trading day on or after each July 1. Under the ESPP, participating employees can authorize the Company to withhold a portion of their base pay during consecutive six-month payment periods for the purchase of shares of the Company’s common stock. At the conclusion of the period, participating employees can purchase shares of the Company’s common stock at 85% of the lesser of the closing price of the common stock on (i) the first business day of the plan period or (ii) the exercise date. The fair value of the purchase rights granted under the ESPP was estimated on the date of grant, using the Black-Scholes option-pricing model. shares under the ESPP.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Taxes
Income Taxes	Note 14: Income Taxes The Company has had no income tax expense due to operating losses incurred for the years ended December 31, 2020 and 2019. The Company has also not recorded any income tax benefits for the net operating losses incurred in each period due to its uncertainty of realizing a benefit from those items. All of the Company’s losses before income taxes were generated in the United States. 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, ​ ​ 2020 ​ 2019 Federal statutory income tax rate ​ ​ 21.0 % ​ 21.0 % Effect of: ​ ​ ​ ​ ​ ​ ​ Change in valuation allowance ​ ​ (22.2) ​ ​ (25.8) ​ Research and development tax credits ​ ​ 0.9 ​ ​ 1.0 ​ State income taxes, net of federal benefit ​ ​ 1.2 ​ ​ 4.3 ​ Other ​ ​ (0.9) ​ ​ (0.5) ​ Effective income tax rate ​ ​ — % ​ — % ​ Net deferred tax assets as of December 31, 2020 and 2019 consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Deferred tax assets: ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 67,368 ​ $ 49,018 Lease liabilities ​ ​ 8,152 ​ ​ 9,369 Stock-based compensation ​ ​ 7,413 ​ ​ 5,414 Capitalized research and development and start-up expenditures ​ ​ 5,258 ​ ​ 6,733 Research and development tax credit carryforwards ​ ​ 2,398 ​ ​ 6,250 Rebates, incentives, trade discounts and allowances ​ ​ 2,177 ​ ​ — Other ​ ​ 2,609 ​ ​ 2,467 Total deferred tax assets ​ $ 95,375 ​ $ 79,251 Deferred tax liabilities: ​ ​ ​ ​ ​ ​ Right-of-use assets ​ ​ (7,810) ​ ​ (9,178) Total deferred tax liabilities ​ $ (7,810) ​ $ (9,178) Valuation allowance ​ $ (87,565) ​ $ (70,073) Net deferred tax assets ​ $ — ​ $ — ​ The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets. Management has considered the Company’s history of cumulative net losses incurred since inception and has concluded that it is more likely than not that the Company will not realize the benefits of the deferred tax assets. Accordingly, a full valuation allowance has been established against the deferred tax assets as of December 31, 2020 and 2019. The valuation allowance increased by $17,492 in 2020 due to an increase in the net operating loss carryforwards and research and development tax credits, partially offset by limitations caused by ownership changes under the provisions of Section 382 and Section 383 of the Internal Revenue Code of 1986. Management reevaluates the positive and negative evidence at each reporting period. As of December 31, 2020 and 2019, the Company had federal net operating loss carryforwards of $243,155 and $168,801, respectively, which may be available to offset future federal tax liabilities and expire at various dates beginning in 2030. As of December 31, 2020 and 2019, the Company had state net operating loss carryforwards of $214,989 and $171,804, respectively, which may be available to offset future state income tax liabilities and expire at various dates beginning in 2030. As of December 31, 2020 and 2019, the Company also had federal and state research and development credit carryforwards of approximately $2,398 and $6,250, respectively, which begin to expire in 2039 (federal) and 2034 (state). Realization of the future tax benefits is dependent on many factors, including the Company’s ability to generate taxable income within the net operating loss carryforward period. Under the provisions of Section 382 of the Internal Revenue Code of 1986, certain substantial changes in the Company’s ownership, including a sale of the Company, or significant changes in ownership due to sales of equity, may have limited, or may limit in the future, the amount of net operating loss carryforwards, which could be used annually to offset future taxable income. The Company previously completed an analysis and determined that an ownership change has materially limited the net operating loss carryforwards and research and development tax credits available to offset future tax liabilities. The Company files its corporate income tax returns in the United States and various states. All tax years since the date of incorporation remain open to examination by the major taxing jurisdictions (state and federal) to which the Company is subject, as carryforward attributes generated in years past may still be adjusted upon examination by the Internal Revenue Service (‘‘IRS’’) or other authorities if they have or will be used in a future period. The Company is not currently under examination by the IRS or any other jurisdictions for any tax year. As of December 31, 2020 and 2019 the Company had no uncertain tax positions. The Company’s policy is to recognize interest and penalties related to income tax matters as a component of income tax expense, of which no interest or penalties were recorded for the years ended December 31, 2020 and 2019.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies.
Commitments and Contingencies	Note 15: Commitments and Contingencies License Agreement After 2016 and until the first commercial sale of product, which occurred in January 2019, the minimum annual payment was $38. Upon the first commercial sale of INVELTYS, the annual minimum payment increased to $113. The Company is obligated to pay JHU low single-digit running royalties based upon a percentage of net sales of the licensed products, which is applied to the annual minimum payment. The Company also has an obligation to pay JHU certain one-time development and commercial milestone payments. During the year ended December 31, 2020, the Company paid JHU $113 in royalty payments associated with the sale of EYSUVIS and INVELTYS. During the year ended December 31, 2019, the Company paid JHU $413 related to the first commercial sale milestone and subsequent royalties. The Company is obligated to pay JHU a $150 milestone payment within 60 days of the first commercial sale of EYSUVIS in the United States which has been included within accrued expenses and other current liabilities on the consolidated balance sheet as of December 31, 2020. The Company recorded other expenses related to the JHU agreement of $134 and $253 for each of the years ended December 31, 2020 and 2019, respectively. The Company’s minimum obligations due under its license agreements as of December 31, 2020, are as follows: ​ ​ ​ ​ ​ Years Ending December 31, ​ ​ 2021 ​ $ 113 2022 ​ ​ 113 2023 ​ ​ 113 2024 ​ ​ 113 2025 ​ ​ 113 Thereafter ​ ​ 900 Total minimum license payments ​ $ 1,465 ​ Other Commitments The commercial supply agreement contains annual minimum purchase requirements, which increased upon FDA approval of EYSUVIS on October 26, 2020. The Company has the following minimum purchase obligations for EYSUVIS and INVELTYS: ​ ​ ​ ​ Years Ending December 31, ​ ​ 2021 ​ $ 2,295 2022 ​ ​ 5,390 2023 ​ ​ 6,285 2024 ​ ​ 7,875 2025 ​ ​ 8,199 Thereafter ​ ​ 17,925 Total minimum purchase commitments ​ $ 47,969 ​ Litigation Guarantees and Indemnifications The Company’s equity agreements and certain other arrangements include standard indemnifications against claims, actions, or other matters that may arise in connection with these arrangements. As of December 31, 2020 and 2019, the Company had not experienced any losses related to these indemnification obligations, and no claims with respect thereto were outstanding. The Company does not expect significant claims related to these indemnification obligations and has no amount accrued related to these contingencies. The Company does not expect these indemnifications to have a material adverse effect on these consolidated financial statements.

Defined Contribution Plan

Defined Contribution Plan	12 Months Ended
	Dec. 31, 2020
Defined Contribution Plan
Defined Contribution Plan	Note 16: Defined Contribution Plan The Company has a 401(k) defined contribution plan (the ‘‘401(k) Plan’’) for substantially all of its employees. Eligible employees may make pretax contributions to the 401(k) Plan up to statutory limits. The Company made discretionary matching contributions of $446 and $454 to the 401(k) Plan during for the years ended December 31, 2020 and 2019, respectively.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2020
Selected Quarterly Financial Data (Unaudited)
Selected Quarterly Financial Data (Unaudited)	Note 17: Selected Quarterly Financial Data (Unaudited) Selected quarterly financial data is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ ​ March 31, ​ June 30, ​ September 30, ​ December 31, ​ 2020 2020 2020 2020 Product revenues, net ​ $ 1,071 ​ $ 833 ​ $ 2,220 ​ $ 2,238 Costs and expenses ​ ​ 21,196 ​ ​ 22,113 ​ ​ 28,062 ​ ​ 31,222 Total other income (expense) ​ ​ (1,830) ​ ​ (2,032) ​ ​ (2,106) ​ ​ (2,128) Net loss attributable to common stockholders ​ $ (21,955) ​ $ (23,312) ​ $ (27,948) ​ $ (31,112) Net loss per share attributable to common stockholders—basic and diluted ​ $ (0.54) ​ $ (0.42) ​ $ (0.50) ​ $ (0.55) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ ​ March 31, ​ June 30, ​ September 30, ​ December 31, ​ 2019 2019 2019 2019 Product revenues, net ​ $ 1,386 ​ $ 2,057 ​ $ 1,451 ​ $ 1,180 Costs and expenses ​ ​ 25,436 ​ ​ 24,467 ​ ​ 23,018 ​ ​ 21,377 Total other income (expense) ​ ​ (1,338) ​ ​ (1,415) ​ ​ (1,609) ​ ​ (1,761) Net loss attributable to common stockholders ​ $ (25,388) ​ $ (23,825) ​ $ (23,176) ​ $ (21,958) Net loss per share attributable to common stockholders—basic and diluted ​ $ (0.75) ​ $ (0.70) ​ $ (0.68) ​ $ (0.63) ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Summary of Significant Accounting Policies
Principles of Consolidation	Principles of Consolidation—
Basis of Presentation	Basis of Presentation The Company expects that its cash, cash equivalents and short-term investments as of December 31, 2020, together with anticipated net revenue from sales of INVELTYS, will enable it to fund its operating expenses, debt service obligations and capital expenditure requirements for at least 12 months from the date these consolidated financial statements were issued. This evaluation is based on relevant conditions and events that are known and reasonably knowable at the date that the consolidated financial statements are issued. As a result, the Company could deplete its available capital resources sooner than it currently expects.
Use of Estimates	Use of Estimates—
Product Revenues, Net	Product Revenues, Net The Company accounts for revenue in accordance with Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers Performance Obligations The Company determined that performance obligations are satisfied and revenue is recognized when a customer takes control of the Company’s products, which occurs at a point in time. This generally occurs upon delivery of the products to customers, at which point the Company recognizes revenue and records accounts receivable. Payment is typically received 70 to 90 days after satisfaction of the Company’s performance obligations. Transaction Price and Variable Consideration Revenue is measured as the amount of consideration the Company expects to receive in exchange for transferring products to a customer (“transaction price”). The transaction price for product sales includes variable consideration related to chargebacks, rebates, sales incentives and allowances, distribution service fees, and returns. The Company will estimate the amount of variable consideration that should be included in the transaction price. These estimates take into consideration a range of possible outcomes that are probability-weighted for relevant factors such as the Company’s historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. These provisions reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained and is included in net sales only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. In general, performance obligations do not include any estimated amounts of variable consideration that are constrained. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. The following table summarizes activity in each of the Company’s product revenue provision and allowance categories for the years ended December 31, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trade Discounts, ​ ​ ​ ​ ​ ​ ​ ​ Allowances and ​ ​ ​ ​ Rebates and ​ ​ Chargebacks (1) Product Returns (2) Incentives (3) Balance as of January 1, 2019 ​ $ — ​ $ — ​ $ — Provision related to current period sales ​ ​ 4,031 ​ ​ 321 ​ ​ 24,812 Credit/payments made ​ ​ (2,248) ​ ​ (141) ​ ​ (14,768) Balance as of December 31, 2019 ​ $ 1,783 ​ $ 180 ​ $ 10,044 Provision related to current period sales ​ ​ 3,937 ​ ​ 207 ​ ​ 23,265 Changes in estimate related to prior period sales ​ ​ 21 ​ ​ 213 ​ ​ 74 Credit/payments made ​ ​ (4,584) ​ ​ — ​ ​ (28,479) Balance as of December 31, 2020 ​ $ 1,157 ​ $ 600 ​ $ 4,904 (1) Trade discounts, allowances and chargebacks include fees for distribution service fees, prompt pay and other discounts, and chargebacks. Trade discounts, allowances and chargebacks are deducted from gross revenue at the time revenues are recognized and are recorded as a reduction to accounts receivable on the Company’s consolidated balance sheets. (2) Provisions for product returns are deducted from gross revenues at the time revenues are recognized and are included in accrued expenses and other current liabilities on the Company’s consolidated balance sheets. (3) Rebates and incentives include managed care rebates, government rebates, co-pay program incentives, and sales incentives and allowances. Provisions for rebates and discounts are deducted from gross revenues at the time revenues are recognized and are included in accrued expenses and other current liabilities on the Company’s consolidated balance sheets. As of December 31, 2020 and 2019, the Company did not have any transaction price allocated to remaining performance obligations and any costs to obtain contracts with customers, including pre-contract costs and set up costs, were immaterial.
Accounts Receivable, net	Accounts Receivable, net The Company recorded no allowance for doubtful accounts as of December 31, 2020 or December 31, 2019. The Company recorded an allowance of $1,157 and $1,783 for expected sales discounts, related to prompt pay discounts and other discounts, contractual fee for service arrangements and chargebacks, to wholesalers and distributors as of December 31, 2020 and December 31, 2019, respectively.
Cost of Product Revenues	Cost of Product Revenues—
Cash and Concentration of Credit Risk	Cash and Concentration of Credit Risk Three Customers comprised 10% or more of the Company’s accounts receivable balance as of December 31, 2020 and 2019. These Customers comprised 39%, 33% and 25% of the accounts receivable balance, respectively, as of December 31, 2020 and 41%, 35% and 23% of the accounts receivable balance, respectively, as of December 31, 2019. To date, the Company has not experienced any losses with respect to the collection of its accounts receivable and believes that its entire accounts receivable balances is collectible as of December 31, 2020. The same three Customers comprised 10% or more of the Company’s revenue during the years ended December 31, 2020 and 2019. These Customers comprised 40%, 29% and 28% of revenue, respectively, during the year ended December 31, 2020 and 39%, 33% and 26% of revenue, respectively, during the year ended December 31, 2019. The Company has no financial instruments with off-balance sheet risk of loss.
Cash Equivalents	Cash Equivalents
Restricted Cash	Restricted Cash
Investments	Investments— Available-for-sale investments are recorded at fair value, with unrealized gains or losses included in comprehensive loss on the consolidated statements of operations and comprehensive loss and in accumulated other comprehensive income or loss on the consolidated balance sheets. Realized gains and losses, interest income earned on the Company’s cash, cash equivalents and investments, and amortization or accretion of discounts and premiums on investments are included within other income (expense). ​ The Company reviews investments for other-than-temporary impairment whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. The Company did not record any such impairments during the year ended December 31, 2020.
Inventory	Inventory ​ Inventory produced that will be used in a promotional sample program is expensed to selling, general and administrative expense when it is designated as a sample. Long-term inventory includes raw materials, work-in-progress and/or finished goods inventory with an anticipated consumption or sale beyond one year based on the Company’s forecasted expectations.
Leases	Leases ​ The components of a lease should be split into three categories: lease components (e.g., land, building, etc.), non-lease components (e.g., common area maintenance, maintenance, consumables, etc.), and non-components (e.g., property taxes, insurance, etc.). Then the fixed and in-substance fixed contract consideration (including any related to non-components) must be allocated based on fair values to the lease components and non-lease components. Although separation of lease and non-lease components is required, certain practical expedients are available to entities. Entities electing the practical expedient would not separate lease and non-lease components. Rather, they would account for each lease component and the related non-lease component together as a single component. The Company’s facilities operating leases have lease and non-lease components which the Company has elected to use the practical expedient and account for each lease component and related non-lease component as one single component. The lease component results in a right-of-use asset being recorded on the consolidated balance sheets and amortized as lease expense on a straight-line basis to the consolidated statements of operations and comprehensive loss.
Property and Equipment, net	Property and Equipment, net Laboratory equipment office and three
Patent Costs	Patent Costs
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets
Segment Information	Segment Information
Research and Development Costs	Research and Development Costs
Accrued Expenses	Accrued Expenses
Stock-Based Compensation	Stock-Based Compensation The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. The assumptions used in calculating the fair value of stock-based payment awards represent management’s best estimates. The Company lacks sufficient company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and will continue to do so until it has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. 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 on common stock and does not expect to pay any cash dividends in the foreseeable future. The fair value of restricted stock units (“RSUs”) and performance stock units (“PSUs”) are equal to the closing sale price of the Company’s common stock on the date of grant.
Income Taxes	Income Taxes The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions and other issues. The Company may recognize the tax benefit from an uncertain tax position only if it is more likely than not that the position will be sustained on examination by the taxing authorities based on the technical merits of the position. The tax benefits recognized in the consolidated financial statements from such a position is measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. As a result, reserves are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized following resolution of any potential contingencies present.
Net Loss per Share	Net Loss per Share and the issuance of unvested RSUs and PSUs The weighted average number of common shares included in the computation of diluted net loss gives effect to all potentially dilutive common equivalent shares, including outstanding stock options, warrants and unvested RSUs and PSUs As of December 31, 2020 and 2019, potentially dilutive securities excluded from the calculation of diluted net loss per share because including such securities would have an anti-dilutive effect consisted of outstanding options to purchase 8,745,127 and 7,453,076 shares of the Company’s common stock, respectively, an aggregate of 942,222 unvested RSUs and PSUs as of December 31, 2020 and an aggregate of 248,505 and 384,163 unexercised warrants as of December 31, 2020 and 2019, respectively.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2018, the Financial Accounting Standards Board (“ Accounting Standards Update (“ Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measuremen In August 2018, the FASB issued ASU 2018-15 , Intangibles – Goodwill and Other – Internal-Use Software -Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 significantly changes the impairment model for most financial assets and certain other instruments. ASU 2016-13 will require immediate recognition of estimated credit losses expected to occur over the remaining life of many financial assets, which will generally result in earlier recognition of allowances for credit losses on loans and other financial instruments. In November 2019, the FASB issued ASU 2019-10, Financial Instruments – Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842) (“ASU 2019-10”) , which is effective for public business entities that meet the definition of an SEC filer, excluding entities eligible to be Smaller Reporting Companies (“SRCs”) as defined by the SEC, for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years and for all other entities, including SRCs, for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. Upon adoption, beginning January 1, 2023, the Company does not expect ASU 2019-10 to have a material effect on its consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Summary of Significant Accounting Policies
Schedule of product revenue provision and allowance categories	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trade Discounts, ​ ​ ​ ​ ​ ​ ​ ​ Allowances and ​ ​ ​ ​ Rebates and ​ ​ Chargebacks (1) Product Returns (2) Incentives (3) Balance as of January 1, 2019 ​ $ — ​ $ — ​ $ — Provision related to current period sales ​ ​ 4,031 ​ ​ 321 ​ ​ 24,812 Credit/payments made ​ ​ (2,248) ​ ​ (141) ​ ​ (14,768) Balance as of December 31, 2019 ​ $ 1,783 ​ $ 180 ​ $ 10,044 Provision related to current period sales ​ ​ 3,937 ​ ​ 207 ​ ​ 23,265 Changes in estimate related to prior period sales ​ ​ 21 ​ ​ 213 ​ ​ 74 Credit/payments made ​ ​ (4,584) ​ ​ — ​ ​ (28,479) Balance as of December 31, 2020 ​ $ 1,157 ​ $ 600 ​ $ 4,904 (1) Trade discounts, allowances and chargebacks include fees for distribution service fees, prompt pay and other discounts, and chargebacks. Trade discounts, allowances and chargebacks are deducted from gross revenue at the time revenues are recognized and are recorded as a reduction to accounts receivable on the Company’s consolidated balance sheets. (2) Provisions for product returns are deducted from gross revenues at the time revenues are recognized and are included in accrued expenses and other current liabilities on the Company’s consolidated balance sheets. (3) Rebates and incentives include managed care rebates, government rebates, co-pay program incentives, and sales incentives and allowances. Provisions for rebates and discounts are deducted from gross revenues at the time revenues are recognized and are included in accrued expenses and other current liabilities on the Company’s consolidated balance sheets.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value of Financial Instruments
Schedule of assets and liabilities measured at fair value on a recurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ Fair Value ​ Level 1 ​ Level 2 ​ Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 63,811 ​ $ 63,811 ​ $ — ​ $ — Short-term investments ​ ​ 76,276 ​ ​ 76,276 ​ ​ — ​ ​ — Total Assets ​ $ 140,087 ​ $ 140,087 ​ $ — ​ $ —

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Investments
Schedule of investments by security type	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ ​ Gross ​ Gross ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ Cost ​ Gains ​ Losses ​ Value U.S. treasury securities $ 26,744 ​ $ 2 ​ $ — ​ $ 26,746 U.S. government agencies securities ​ 49,528 ​ ​ 2 ​ ​ — ​ ​ 49,530 Total $ 76,272 ​ $ 4 ​ $ — ​ $ 76,276

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2020
Inventory
Schedule of Inventory	Inventory consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ Raw materials ​ $ 801 ​ $ 1,387 Work in progress ​ ​ 6,437 ​ ​ 4,166 Finished goods ​ ​ 4,210 ​ ​ 2,873 Total inventory ​ $ 11,448 ​ $ 8,426

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Prepaid Expenses and Other Current Assets
Schedule of prepaid expenses and other current assets	Prepaid expenses and other current assets, consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ Insurance ​ $ 1,201 ​ $ 906 Deposits ​ ​ 606 ​ ​ 699 Non-trade receivables ​ ​ 250 ​ ​ 1,535 Other ​ ​ 949 ​ ​ 684 Prepaid expenses and other current assets ​ $ 3,006 ​ $ 3,824

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Property and Equipment, Net
Schedule of property and equipment, net	Property and equipment, net, consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ Equipment ​ $ 2,652 ​ $ 2,627 Furniture and office equipment ​ ​ 1,144 ​ ​ 1,144 Computer hardware and software ​ ​ 1,108 ​ ​ 892 Leasehold improvements ​ ​ 356 ​ ​ 356 Construction in progress ​ ​ 1,330 ​ ​ 195 Property and equipment — ​ ​ 6,590 ​ ​ 5,214 Less: Accumulated depreciation ​ ​ (3,424) ​ ​ (2,516) Property and equipment—net ​ $ 3,166 ​ $ 2,698

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Accrued Expenses
Schedule of accrued expenses	Accrued expenses consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ Compensation and benefits ​ $ 9,676 ​ $ 6,502 Accrued revenue reserves (1) ​ ​ 5,224 ​ ​ 9,482 Commercial costs ​ ​ 2,103 ​ ​ 930 Professional services ​ ​ 926 ​ ​ 760 Contract manufacturing ​ ​ 336 ​ ​ 630 Development costs ​ ​ 154 ​ ​ 1,600 Other ​ ​ 552 ​ ​ 1,025 Accrued expenses ​ $ 18,971 ​ $ 20,929 (1) As of December 31, 2020 and 2019, $280 and $742 of additional revenue reserves were in accounts payable, respectively.

Lease (Tables)

Lease (Tables)	12 Months Ended
	Dec. 31, 2020
Lease
Schedule of components of lease expense and related cash flows	The components of lease expense and related cash flows were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, ​ 2020 2019 Lease cost ​ ​ Operating lease cost ​ $ 4,741 ​ $ 4,614 Variable lease cost ​ ​ 1,848 ​ ​ 1,766 Total lease cost ​ $ 6,589 ​ $ 6,380 ​ ​ ​ ​ ​ ​ ​ Operating cash outflows from operating leases ​ $ 5,981 ​ $ 5,445
Schedule of maturities of operating lease liability	​ ​ ​ ​ ​ Years Ending December 31, ​ 2021 ​ $ 4,274 2022 ​ ​ 4,062 2023 ​ ​ 3,960 2024 ​ ​ 4,079 2025 ​ ​ 4,201 Thereafter ​ ​ 27,135 Total minimum lease payments ​ ​ 47,711 Less: amount representing interest ​ ​ (19,038) Present value of lease liabilities ​ $ 28,673

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt
Schedule of carrying value of debt	The components of the carrying value of the debt as of December 31, 2020 and December 31, 2019 are detailed below: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 Principal loan balance ​ $ 75,000 ​ $ 75,000 Unamortized debt discount and issuance cost ​ ​ (3,088) ​ ​ (3,999) Cumulative accretion of exit fee ​ ​ 331 ​ ​ 183 Long-term debt, net ​ $ 72,243 ​ $ 71,184
Schedule of maturities of long-term debt	The annual principal payments due under the Athyrium Credit Facility as of December 31, 2020 were as follows: ​ ​ ​ ​ Years Ending December 31, ​ ​ 2021 ​ $ — 2022 ​ ​ 16,665 2023 ​ ​ 33,330 2024 ​ ​ 25,005 Total ​ $ 75,000

Warrants (Tables)

Warrants (Tables)	12 Months Ended
	Dec. 31, 2020
Warrants
Schedule of outstanding warrants	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Exercisable at ​ ​ Exercise Expiration Exercisable December 31, December 31, Issued Price ​ Date ​ From ​ 2020 ​ 2019 2013 ​ $ 7.50 ​ April 2021 ​ July 2017 ​ 33,333 ​ 82,816 2014 ​ $ 7.50 November 2024 July 2017 ​ 16,000 ​ 16,000 2016 ​ $ 8.27 October 2026 September 2017 ​ 14,512 ​ 14,512 2018 ​ $ 12.18 ​ October 2025 ​ October 2018 ​ 184,660 ​ 184,660 ​ ​ ​ ​ ​ ​ ​ ​ ​ 248,505 ​ 297,988

Common and Preferred Stock (Tab

Common and Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2020
Common and Preferred Stock
Schedule of reserved common stock shares upon exercise of rights under equity compensation plans	​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ 2020 2019 Warrant rights to acquire common stock ​ 248,505 ​ 384,163 ESPP ​ 484,772 ​ 438,307 Outstanding inducement stock option awards ​ 945,842 ​ 705,500 2009 Plan ​ 2,251,570 ​ 2,530,586 2017 Plan ​ 7,813,784 ​ 4,429,849 Total ​ 11,744,473 ​ 8,488,405

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Stock-based Compensation
Summary of option activity for employee and non employee awards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ Weighted ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Number of ​ Exercise ​ Contractual ​ Intrinsic ​ Shares Price Term Value ​ ​ ​ ​ ​ ​ (Years) ​ (in thousands) Outstanding as of January 1, 2020 ​ 7,453,076 ​ $ 7.46 ​ 7.7 ​ $ 1,313 Granted ​ 1,816,222 ​ ​ 4.63 ​ ​ ​ ​ ​ Exercised ​ (345,479) ​ ​ 3.15 ​ ​ ​ ​ ​ Forfeited ​ (178,692) ​ ​ 8.30 ​ ​ ​ ​ ​ Outstanding as of December 31, 2020 ​ 8,745,127 ​ $ 7.03 ​ 7.3 ​ $ 16,275 Vested or expected to vest as of December 31, 2020 ​ 8,745,127 ​ $ 7.03 ​ 7.3 ​ $ 16,275 Options exercisable as of December 31, 2020 ​ 5,362,040 ​ $ 7.45 ​ 6.5 ​ $ 10,235
Schedule of assumptions used in determining fair value of the stock options granted	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 Expected volatility 79.6% – 82.5% ​ 80.7% – 83.7% Risk-free interest rate 0.37% – 1.73% ​ 1.44% – 2.58% Expected dividend yield ​ 0% ​ ​ ​ 0% ​ Expected term (in years) 5.91 – 6.08 ​ 5.27 – 6.63
Schedule of stock based compensation expense	​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, ​ 2020 2019 ​ ​ ​ ​ ​ ​ ​ Cost of product revenues ​ $ 92 ​ $ 268 Research and development ​ ​ 3,083 ​ ​ 2,844 Selling, general and administrative ​ ​ 10,137 ​ ​ 6,879 Total ​ $ 13,312 ​ $ 9,991
Summary of the outstanding RSUs	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Average ​ ​ ​ ​ ​ Grant Date ​ ​ Shares ​ ​ Fair Value Unvested and outstanding balance as of January 1, 2020 ​ — ​ $ — Changes during the period: ​ ​ ​ ​ ​ RSUs granted ​ 263,560 ​ ​ 11.70 PSUs granted ​ 693,537 ​ ​ 11.70 PSUs forfeited ​ (14,875) ​ ​ 11.70 Unvested and outstanding balance as of December 31, 2020 ​ 942,222 ​ $ 11.70

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Taxes
Schedule of income tax reconciliation based on federal statutory rate	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ ​ December 31, ​ ​ 2020 ​ 2019 Federal statutory income tax rate ​ ​ 21.0 % ​ 21.0 % Effect of: ​ ​ ​ ​ ​ ​ ​ Change in valuation allowance ​ ​ (22.2) ​ ​ (25.8) ​ Research and development tax credits ​ ​ 0.9 ​ ​ 1.0 ​ State income taxes, net of federal benefit ​ ​ 1.2 ​ ​ 4.3 ​ Other ​ ​ (0.9) ​ ​ (0.5) ​ Effective income tax rate ​ ​ — % ​ — %
Schedule of net deferred tax assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Deferred tax assets: ​ ​ ​ ​ ​ ​ Net operating loss carryforwards ​ $ 67,368 ​ $ 49,018 Lease liabilities ​ ​ 8,152 ​ ​ 9,369 Stock-based compensation ​ ​ 7,413 ​ ​ 5,414 Capitalized research and development and start-up expenditures ​ ​ 5,258 ​ ​ 6,733 Research and development tax credit carryforwards ​ ​ 2,398 ​ ​ 6,250 Rebates, incentives, trade discounts and allowances ​ ​ 2,177 ​ ​ — Other ​ ​ 2,609 ​ ​ 2,467 Total deferred tax assets ​ $ 95,375 ​ $ 79,251 Deferred tax liabilities: ​ ​ ​ ​ ​ ​ Right-of-use assets ​ ​ (7,810) ​ ​ (9,178) Total deferred tax liabilities ​ $ (7,810) ​ $ (9,178) Valuation allowance ​ $ (87,565) ​ $ (70,073) Net deferred tax assets ​ $ — ​ $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies.
Schedule of minimum obligations due	​ ​ ​ ​ ​ Years Ending December 31, ​ ​ 2021 ​ $ 113 2022 ​ ​ 113 2023 ​ ​ 113 2024 ​ ​ 113 2025 ​ ​ 113 Thereafter ​ ​ 900 Total minimum license payments ​ $ 1,465
Schedule of minimum purchase obligations	The Company has the following minimum purchase obligations for EYSUVIS and INVELTYS: ​ ​ ​ ​ Years Ending December 31, ​ ​ 2021 ​ $ 2,295 2022 ​ ​ 5,390 2023 ​ ​ 6,285 2024 ​ ​ 7,875 2025 ​ ​ 8,199 Thereafter ​ ​ 17,925 Total minimum purchase commitments ​ $ 47,969

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
Selected Quarterly Financial Data (Unaudited)
Quarterly Financial Information	Selected quarterly financial data is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ ​ March 31, ​ June 30, ​ September 30, ​ December 31, ​ 2020 2020 2020 2020 Product revenues, net ​ $ 1,071 ​ $ 833 ​ $ 2,220 ​ $ 2,238 Costs and expenses ​ ​ 21,196 ​ ​ 22,113 ​ ​ 28,062 ​ ​ 31,222 Total other income (expense) ​ ​ (1,830) ​ ​ (2,032) ​ ​ (2,106) ​ ​ (2,128) Net loss attributable to common stockholders ​ $ (21,955) ​ $ (23,312) ​ $ (27,948) ​ $ (31,112) Net loss per share attributable to common stockholders—basic and diluted ​ $ (0.54) ​ $ (0.42) ​ $ (0.50) ​ $ (0.55) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ ​ March 31, ​ June 30, ​ September 30, ​ December 31, ​ 2019 2019 2019 2019 Product revenues, net ​ $ 1,386 ​ $ 2,057 ​ $ 1,451 ​ $ 1,180 Costs and expenses ​ ​ 25,436 ​ ​ 24,467 ​ ​ 23,018 ​ ​ 21,377 Total other income (expense) ​ ​ (1,338) ​ ​ (1,415) ​ ​ (1,609) ​ ​ (1,761) Net loss attributable to common stockholders ​ $ (25,388) ​ $ (23,825) ​ $ (23,176) ​ $ (21,958) Net loss per share attributable to common stockholders—basic and diluted ​ $ (0.75) ​ $ (0.70) ​ $ (0.68) ​ $ (0.63)

Nature of business (Details)

Nature of business (Details) - USD ($) $ / shares in Units, $ in Thousands	May 07, 2020	Apr. 03, 2020	Mar. 11, 2020	Oct. 11, 2018	Oct. 05, 2018	Aug. 09, 2018	Jan. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Oct. 01, 2018
Equity Offerings
Common stock offering, net of offering costs										$ 125,423
Common stock, par value								$ 0.001		$ 0.001	$ 0.001
Underwriters discount and offering costs										$ 8,475
Accumulated deficit								$ (399,783)		(399,783)	$ (295,456)
Net proceeds										$ 158,557	$ 8,425
2018 Shelf Registration
Equity Offerings
Common stock offering, net of offering costs (in shares)				8,625,000	7,500,000					30,549,976
Common stock offering, net of offering costs										$ 231,666
Net proceeds				$ 66,132
Share authorized value (shelf)						$ 250,000		18,334		18,334
Registration period						3 years
Price per share					$ 8.25
Underwriter's option
Equity Offerings
Common stock offering, net of offering costs (in shares)		979,371	2,400,000		1,125,000
Period granted			30 days
Price per share		$ 7.89
Net proceeds		$ 7,216
2020 Shelf Registration
Equity Offerings
Share authorized value (shelf)								$ 275,000		275,000
Registration period	3 years
2020 Shelf Registration | Maximum
Equity Offerings
Additional authorized value of securities	$ 350,000
ATM
Equity Offerings
Common stock offering, net of offering costs (in shares)								2,821,059	2,352,671		2,592,934
Common stock offering, net of offering costs								$ 20,612
Additional authorized value of securities								$ 35,000		35,000
Net proceeds									$ 12,546		$ 13,059
Share authorized value (ATM)										$ 53,751
Sales agreement					$ 50,000
ATM | Subsequent Event
Equity Offerings
Common stock offering, net of offering costs (in shares)							2,552,457
Common stock offering, net of offering costs							$ 18,226
ATM | Maximum
Equity Offerings
Additional authorized value of securities	$ 75,000
2020 Offering
Equity Offerings
Common stock offering, net of offering costs (in shares)		16,979,371	16,000,000
Net proceeds			$ 118,207
Price per share			$ 7.89
Net proceeds		$ 125,423
Athyrium | Term Loan A
Equity Offerings
Aggregate principal amount												$ 75,000
Athyrium | Term Loan B
Equity Offerings
Aggregate principal amount												$ 35,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Basis of Presentation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Summary of Significant Accounting Policies
Net loss	$ (31,112)	$ (27,948)	$ (23,312)	$ (21,955)	$ (21,958)	$ (23,176)	$ (23,825)	$ (25,388)	$ (104,327)	$ (94,347)
Cash used in operations									$ (90,694)	$ (92,720)

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Performance Obligations (Details)	12 Months Ended
	Dec. 31, 2020
Summary of Significant Accounting Policies
Minimum period in which payment is typically received	70 days
Maximum period in which payment is typically received	90 days

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Product Revenue Provision and Allowance Categories (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Product information
Allowance for doubtful accounts	$ 0	$ 0
Sales discounts and contractual fee for service arrangements
Product information
Allowance for doubtful accounts	1,157	1,783
Trade Discounts, Allowances and Chargebacks
Product information
Beginning balance	1,783
Provision related to current period sales	3,937	4,031
Changes in estimate related to prior period sales	21
Credit/payments made	(4,584)	(2,248)
Ending balance	1,157	1,783
Product Returns
Product information
Beginning balance	180
Provision related to current period sales	207	321
Changes in estimate related to prior period sales	213
Credit/payments made		(141)
Ending balance	600	180
Rebates and Incentives
Product information
Beginning balance	10,044
Provision related to current period sales	23,265	24,812
Changes in estimate related to prior period sales	74
Credit/payments made	(28,479)	(14,768)
Ending balance	$ 4,904	$ 10,044

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Cash, Concentration of Credit Risk and Restricted Cash (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)Counterparty	Dec. 31, 2019USD ($)
Cash and Concentration of Credit Risk
Number of counterparties | Counterparty	3
Restricted Cash
Restricted cash | $	$ 12,492	$ 12,582
First Customer
Cash and Concentration of Credit Risk
Percent of total accounts receivable	39.00%	41.00%
Percent of total revenue	40.00%	39.00%
Second Customer
Cash and Concentration of Credit Risk
Percent of total accounts receivable	33.00%	35.00%
Percent of total revenue	29.00%	33.00%
Third Customer
Cash and Concentration of Credit Risk
Percent of total accounts receivable	25.00%	23.00%
Percent of total revenue	28.00%	26.00%

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - PPE, Asset Impairment and Tax Incentives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Impairment of Long-Lived Assets
Long-lived asset impairment	$ 0	$ 0
Laboratory Equipment | Minimum
Property and Equipment, net
Useful life (in years)	3 years
Laboratory Equipment | Maximum
Property and Equipment, net
Useful life (in years)	5 years
Office equipment | Minimum
Property and Equipment, net
Useful life (in years)	3 years
Office equipment | Maximum
Property and Equipment, net
Useful life (in years)	5 years
Computer hardware and software | Minimum
Property and Equipment, net
Useful life (in years)	3 years
Computer hardware and software | Maximum
Property and Equipment, net
Useful life (in years)	5 years

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Options
Stock-based compensation
Outstanding securities excluded from the computation of diluted weighted average shares outstanding (in shares)	8,745,127	7,453,076
RSU and PSU
Stock-based compensation
Outstanding securities excluded from the computation of diluted weighted average shares outstanding (in shares)	942,222
Warrants
Stock-based compensation
Outstanding securities excluded from the computation of diluted weighted average shares outstanding (in shares)	248,505	384,163

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Impact to Previously Reported Results (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Impacts to Previously Reported Results
Right-of-use assets	$ 27,853	$ 29,781
Accrued expenses	18,971	20,929
Lease liabilities	1,530	1,327
Accrued expenses and other current liabilities	$ (1,763)	$ 9,630

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Recurring and Nonrecurring Fair value Measurements Within Hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy		$ 0
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	$ 140,087
Recurring | Level 1 | Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	63,811
Recurring | Level 1 | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	76,276
Fair Value | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	140,087
Fair Value | Recurring | Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	63,811
Fair Value | Recurring | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Financial assets by level within fair value hierarchy	$ 76,276

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Fair value measurement levels (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Fair Value of Financial Instruments
Transfer from level 1 to level 2, Assets	$ 0
Transfer from level 2 to level 1, Assets	0
Transfer from level 1 to level 2, Liabilities	0
Transfer from level 2 to level 1, Liabilities	0
Transfer into level 3, Assets	0
Transfer out of level 3, Assets	0
Transfer into level 3, Liability	$ 0

Investments (Details)

Investments (Details) $ in Thousands	Dec. 31, 2020USD ($)
Investments by security type
Amortized Cost	$ 76,272
Gross Unrealized Gains	4
Fair Value	76,276
U.S. treasury securities
Investments by security type
Amortized Cost	26,744
Gross Unrealized Gains	2
Fair Value	26,746
U.S. government agencies securities
Investments by security type
Amortized Cost	49,528
Gross Unrealized Gains	2
Fair Value	$ 49,530

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Inventory
Raw Materials	$ 801	$ 1,387
Work in Progress	6,437	4,166
Finished Goods	4,210	2,873
Total inventory	11,448	8,426
Inventory	5,229	4,648
Long-term inventory	$ 6,219	$ 3,778

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expenses and Other Current Assets
Insurance	$ 1,201	$ 906
Deposits	606	699
Non-trade receivables	250	1,535
Other	949	684
Prepaid expenses and other current assets	$ 3,006	$ 3,824

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property and Equipment, net
Property and equipment-at cost	$ 6,590	$ 5,214
Less: Accumulated depreciation	(3,424)	(2,516)
Property and equipment-net	3,166	2,698
Depreciation	908	843
Equipment
Property and Equipment, net
Property and equipment-at cost	2,652	2,627
Leasehold improvements
Property and Equipment, net
Property and equipment-at cost	356	356
Computer hardware and software
Property and Equipment, net
Property and equipment-at cost	1,108	892
Furniture and office equipment
Property and Equipment, net
Property and equipment-at cost	1,144	1,144
Construction in progress
Property and Equipment, net
Property and equipment-at cost	$ 1,330	$ 195

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Compensation and benefits	$ 9,676	$ 6,502
Accrued revenue reserves	5,224	9,482
Development costs	154	1,600
Professional services	926	760
Commercial cost	2,103	930
Contract manufacturing	336	630
Other	552	1,025
Accrued expenses	18,971	20,929
Accounts payable
Accrued revenue reserves	$ 280	$ 742

Lease (Details)

Lease (Details) $ in Thousands	Feb. 28, 2018	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)item	Mar. 31, 2019	Nov. 15, 2018
Leases
Lease term				3 years
Restricted cash		$ 12,492	$ 12,582
Variable lease cost		$ 1,848	$ 1,766
Remaining lease term		1 year 2 months 12 days
Number of vehicles leased under a master fleet lease agreement | item			65
Amount borrowed		$ 450	$ 450
Lease cost
Operating lease cost		4,741	4,614
Variable Lease, Cost		1,848	1,766
Total lease cost		6,589	6,380
Operating cash outflows from operating leases		5,981	5,445
Operating Lease, Right-of-Use Asset		27,853	29,781
Watertown Lease
Leases
Lease term	8 years				13 years
Restricted cash		$ 2,042	$ 2,042
Existence of option to extend	true
Renewal term	5 years
Lease cost
Remaining lease term		10 years 9 months 18 days
Present value of lease payments, discounted					9.90%

Lease - Future Minimum Commitme

Lease - Future Minimum Commitments Due (Details) - Operating Lease Obligations $ in Thousands	Dec. 31, 2020USD ($)
Future minimum commitments due
2021	$ 4,274
2022	4,062
2023	3,960
2024	4,079
2025	4,201
Thereafter	27,135
Total minimum lease payments	47,711
Less: amount representing interest	(19,038)
Present value of lease liabilities	$ 28,673

Debt (Details)

Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt instruments
Amount borrowed	$ 450	$ 450
Interest expense	$ 8,589	$ 8,480

Debt - Athyrium Credit Facility

Debt - Athyrium Credit Facility (Details) $ / shares in Units, $ in Thousands	Oct. 01, 2018USD ($)item$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)shares
Debt instruments
Number of features of embedded derivative | item	2
Number of derivatives | item	1
Restricted cash		$ 10,000	$ 10,000
Warrant exercisable | shares		248,505	297,988
Interest expense		$ 8,589	$ 8,480
Warrants 2018
Debt instruments
Exercise Price | $ / shares		$ 12.18
Warrant exercisable | shares		184,660	184,660
Athyrium Credit Facility
Debt instruments
Aggregate principal amount		$ 75,000	$ 75,000
Cumulative accretion of exit fee		331	183
Debt issuance costs		3,088	3,999
Interest expense		8,440	8,316
Amortization of debt discount		910	807
Contractual coupon interest		$ 7,530	$ 7,509
Athyrium | Athyrium Credit Facility
Debt instruments
Aggregate principal amount	$ 110,000
Debt term (in years)	6 years
Effective interest rate		11.63%
Athyrium | Athyrium Credit Facility | Warrants 2018
Debt instruments
Warrant to purchase shares of common stock | shares	270,835
Exercise Price | $ / shares	$ 12.18456
Warrant exercisable | shares	184,660
Remaining warrant exercisable upon condition | shares	86,175
Initial fair value of the Warrant	$ 1,900
Unamortized discount	1,980
Athyrium | Term Loan A
Debt instruments
Aggregate principal amount	$ 75,000
Line of Credit Facility, Interest Rate During Period	9.875%
Exit fee of the total principal payments (as a percent)	1.00%
Cumulative accretion of exit fee	$ 750
Present value of prepayments if prepayment occurs prior to the second anniversary (as a percent)	105.00%
Prepayments if prepayment occurs on or after the second anniversary of the applicable date of issuance but prior to the third anniversary (as a percent)	3.00%
Prepayments if prepayment occurs on or after the third anniversary (as a percent)	2.00%
Prepayments if prepayment occurs after the fourth anniversary (as a percent)	0.00%
Additional interest rate upon an event of default accrued (as a percent)	3.00%
Total interest rate (as a percent)	12.875%
Financial covenant amount	$ 10,000
Athyrium | Term Loan B
Debt instruments
Aggregate principal amount	$ 35,000

Debt - Carrying Value (Details)

Debt - Carrying Value (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt instruments
Long-term debt, net	$ 72,243	$ 71,184
Athyrium Credit Facility
Debt instruments
Principal Loan Balance	75,000	75,000
Unamortized debt discount and issuance cost	(3,088)	(3,999)
Cumulative accretion of exit fee	331	183
Long-term debt, net	$ 72,243	$ 71,184

Debt - Future annual principal

Debt - Future annual principal payments (Details) $ in Thousands	Dec. 31, 2020USD ($)
Maturities of long-term debt
2022	$ 16,665
2023	33,330
2024	25,005
Total	$ 75,000

Warrants (Details)

Warrants (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Preferred stock warrants
Shares Exercisable	248,505	297,988
Warrants 2013
Preferred stock warrants
Exercise Price	$ 7.50
Shares Exercisable	33,333	82,816
Warrants 2014
Preferred stock warrants
Exercise Price	$ 7.50
Shares Exercisable	16,000	16,000
Warrants 2016
Preferred stock warrants
Exercise Price	$ 8.27
Shares Exercisable	14,512	14,512
Warrants 2018
Preferred stock warrants
Exercise Price	$ 12.18
Shares Exercisable	184,660	184,660

Common and Preferred Stock (Det

Common and Preferred Stock (Details)	12 Months Ended
	Dec. 31, 2020Votedirector$ / sharesshares	Dec. 31, 2019$ / sharesshares	Dec. 31, 2018shares
Common stock and preferred stock
Common stock, authorized	120,000,000	120,000,000
Common stock, par value | $ / shares	$ 0.001	$ 0.001
Common stock, shares issued	58,915,375	36,086,254
Common stock, shares outstanding	58,915,375	36,086,254
Preferred stock, authorized	5,000,000	5,000,000
Preferred stock, shares outstanding	0	0
Number of votes per common share for each outstanding share | Vote	1
Number of directors granted | director	1
Common stock shares reserved for future issuance	11,744,473	8,488,405
Warrants
Common stock and preferred stock
Common stock shares reserved for future issuance	248,505	384,163
Employee and Non-Employee Stock Options
Common stock and preferred stock
Common stock shares reserved for future issuance	484,772	438,307
2009 stock option plan
Common stock and preferred stock
Common stock shares reserved for future issuance	2,251,570	2,530,586
2017 stock option plan
Common stock and preferred stock
Common stock shares reserved for future issuance	7,813,784	4,429,849
Stock Options
Common stock and preferred stock
Common stock shares reserved for future issuance	945,842	705,500
Common stock.
Common stock and preferred stock
Number of votes entitled to each share held | Vote	1
2017 Employee Stock Purchase Plan
Common stock and preferred stock
Number of common stock issuable upon exercise of rights under equity compensation plans			223,341
2017 Employee Stock Purchase Plan | Maximum
Common stock and preferred stock
Number of common stock issuable upon exercise of rights under equity compensation plans	893,441
2017 Equity Incentive Plan
Common stock and preferred stock
Common stock shares reserved for future issuance	1,323,847
2017 Equity Incentive Plan | Maximum
Common stock and preferred stock
Common stock shares reserved for future issuance	2,251,570
2017 Equity Incentive Plan | Minimum
Common stock and preferred stock
Common stock shares reserved for future issuance	3,573,766
Percentage of aggregate number of common shares reserved for future issuance (as a percent)	4.00%

Stock-based Compensation - Stoc

Stock-based Compensation - Stock Incentive Plans (Details) - shares	Jun. 25, 2020	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Common stock available for future grant		11,744,473	8,488,405
2017 Equity Incentive Plan
Stock-based compensation
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	2,000,000
Common stock available for future grant		1,323,847
2017 Equity Incentive Plan | Maximum
Stock-based compensation
Common stock available for future grant		2,251,570
2017 Equity Incentive Plan | Minimum
Stock-based compensation
Common stock available for future grant		3,573,766
Percentage of aggregate number of common shares reserved for future issuance (as a percent)		4.00%
Employee and Non-Employee Stock Options
Stock-based compensation
Common stock available for future grant		484,772	438,307
Employee and Non-Employee Stock Options | 2009 plan
Stock-based compensation
Options Expiry Term		10 years
Vesting Period		4 years

Stock-based Compensation - Indu

Stock-based Compensation - Inducement Stock Option Awards (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Anniversary of the share-based compensation arrangement	1 year
Employee | Non-statutory Stock Options
Stock-based compensation
Options Expiry Term	4 years
Vesting Period	3 years
Number of common stock issuable upon exercise of rights under equity compensation plans	350,800	207,500
Percentage of vesting of share-based compensation awards on the one year anniversary of the grant date	25.00%
Percentage of vesting of share-based compensation awards after the year anniversary of the grant date	75.00%

Stock-based Compensation - St_2

Stock-based Compensation - Stock Options (Details) - 2009 plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of Shares
Outstanding at the beginning of the period (in shares)	7,453,076
Granted (in shares)	1,816,222
Exercised (in shares)	(345,479)
Forfeited	(178,692)
Outstanding at the end of the period (in shares)	8,745,127	7,453,076
Vested and expected to vest (in shares)	8,745,127
Options exercisable (in shares)	5,362,040
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 7.46
Granted (in dollars per share)	4.63
Exercised (in dollars per share)	3.15
Forfeited (in dollars per share)	8.30
Outstanding at the end of the period (in dollars per share)	7.03	$ 7.46
Vested and expected to vest (in dollars per share )	7.03
Options exercisable (in dollars per shares)	$ 7.45
Weighted Average Remaining Contractual Term
Weighted average period	7 years 3 months 18 days	7 years 8 months 12 days
Vested and expected to vest	7 years 3 months 18 days
Options exercisable	6 years 6 months
Aggregate Intrinsic Value
Outstanding at the beginning of the period (in dollars)	$ 1,313
Outstanding at the end of the period (in dollars)	16,275	$ 1,313
Vested and expected to vest (in dollars)	16,275
Options exercisable (in dollars)	$ 10,235

Stock-based Compensation - Fair

Stock-based Compensation - Fair Value Assumptions (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Assumptions used in determining fair value of the stock options granted
Expected volatility (minimum)	79.60%	80.70%
Expected volatility (maximum)	82.50%	83.70%
Risk-free interest rate (minimum)	0.37%	1.44%
Risk-free interest rate (maximum)	1.73%	2.58%
Expected dividend yield	0.00%	0.00%
Minimum
Assumptions used in determining fair value of the stock options granted
Expected term (in years)	5 years 10 months 28 days	5 years 3 months 7 days
Maximum
Assumptions used in determining fair value of the stock options granted
Expected term (in years)	6 years 29 days	6 years 7 months 17 days

Stock-based Compensation (Detai

Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Weighted average grant date fair value of options granted	$ 3.20	$ 3.45
2009 plan
Stock-based compensation
Unrecognized compensation expense	$ 15,753	$ 19,201
Weighted average expense recognition period	2 years 4 months 6 days	2 years 3 months 21 days

Stock-based Compensation - St_3

Stock-based Compensation - Stock-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Stock based compensation expense	$ 13,312	$ 9,991
Cost of product revenues
Stock-based compensation
Stock based compensation expense	92	268
Research and development
Stock-based compensation
Stock based compensation expense	3,083	2,844
Selling, general and administrative
Stock-based compensation
Stock based compensation expense	$ 10,137	$ 6,879

Stock-based Compensation - Comp

Stock-based Compensation - Compensation expense - INVELTYS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Stock based compensation expense	$ 13,312	$ 9,991
Exercise of stock options	1,087	42
Total intrinsic value of options exercised	2,124	98
Inventories | INVELTYS
Stock-based compensation
Stock based compensation expense	$ 888	$ 59

Stock-based Compensation - Rest

Stock-based Compensation - Restricted Stock Units narrative (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense		$ 13,312	$ 9,991
Non-vested and outstanding balance at end of period (in shares)		942,222
RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		263,560
PSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		693,537
RSU and PSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested and outstanding balance at end of period (in shares)		942,222
Unamortized stock-based compensation expense		$ 7,315
Weighted average expense recognition period		1 year 1 month 28 days
Executive Officer | RSU | First anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	135,560
Vesting percentage	50.00%
Executive Officer | RSU | Second anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	50.00%
Executive Officer | PSU | First anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	693,537
Vesting percentage	50.00%
Executive Officer | PSU | Second anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	50.00%
Director | RSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	128,000

Stock-based Compensation - RSUs

Stock-based Compensation - RSUs and PSUs (Details)	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Shares
Non-vested and outstanding balance at end of period (in shares) | shares	942,222
Weighted Average Grant Date Fair Value
Non-vested and outstanding balance at end of period (in dollars per share) | $ / shares	$ 11.70
RSU
Shares
Granted (in shares) | shares	263,560
Weighted Average Grant Date Fair Value
Granted (in dollars per share) | $ / shares	$ 11.70
PSU
Shares
Granted (in shares) | shares	693,537
Forfeited (in shares) | shares	(14,875)
Weighted Average Grant Date Fair Value
Granted (in dollars per share) | $ / shares	$ 11.70
Forfeited (in dollars per shares) | $ / shares	$ 11.70

Stock-based Compensation - Empl

Stock-based Compensation - Employee Stock Purchase Plan (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)periodshares	Dec. 31, 2019USD ($)shares	Dec. 31, 2018shares
Stock-based compensation
Stock-based compensation expense | $	$ 13,966	$ 10,049
2017 Employee Stock Purchase Plan
Stock-based compensation
Shares Authorized			223,341
Employee basic pay holding period	6 months
Number of offering periods | period	2
Percentage of market value at which employee may purchase stock	85.00%	85.00%
Issuance under employee stock purchase plan (in shares)	314,397	123,664
2017 Employee Stock Purchase Plan | Maximum
Stock-based compensation
Shares Authorized	893,441
Threshold percentage of share available to grant	1.00%

Stock-based Compensation - ESPP

Stock-based Compensation - ESPP Stock-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Stock based compensation expense	$ 13,312	$ 9,991
Cost of product revenues
Stock-based compensation
Stock based compensation expense	92	268
Research and development
Stock-based compensation
Stock based compensation expense	3,083	2,844
Selling, general and administrative
Stock-based compensation
Stock based compensation expense	$ 10,137	$ 6,879

Stock-based Compensation - Rese

Stock-based Compensation - Reserved Shares (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation
Common stock shares reserved for future issuance	11,744,473	8,488,405
Employee and Non-Employee Stock Options
Stock-based compensation
Common stock shares reserved for future issuance	484,772	438,307

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of the U.S. federal statutory income tax rate (Details)-old	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Taxes
Federal statutory income tax rate	21.00%	21.00%
Change in valuation allowance	(22.20%)	(25.80%)
Research and development tax credits	0.90%	1.00%
State income taxes, net of federal benefit	1.20%	4.30%
Other	(0.90%)	(0.50%)

Income Taxes - Net deferred tax

Income Taxes - Net deferred tax assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Taxes
Net operating loss carryforwards	$ 67,368	$ 49,018
Lease liabilities	8,152	9,369
Stock-based compensation	7,413	5,414
Capitalized research and development and start-up expenditures	5,258	6,733
Research and development tax credit carryforwards	2,398	6,250
Rebates, incentives, trade discounts and allowances	2,177
Other	2,609	2,467
Total deferred tax assets	95,375	79,251
Right-of-use assets	(7,810)	(9,178)
Total deferred tax liabilities	(7,810)	(9,178)
Valuation allowance	$ (87,565)	$ (70,073)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income tax expense	$ 0	$ 0
Change in valuation allowance	17,492
Uncertain tax positions	0	0
Interest or penalties recorded	0	0
Federal
Net operating loss carryforwards	243,155	168,801
State
Net operating loss carryforwards	$ 214,989	$ 171,804

Commitments and Contingencies -

Commitments and Contingencies - License Agreement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Contingencies
Minimum annual payment	$ 38
License fee, if the company achieves the first commercial sale	113
Research and development expenses	18,352	$ 27,275
The Johns Hopkins University ("JHU")
Contingencies
First commercial sale milestone	113	413
Research and development expenses	134	$ 253
The Johns Hopkins University ("JHU") | Accrued expenses and other current liabilities
Contingencies
Milestone payment	$ 150
Time within milestone payment must be made by first commercial sale of the product	60 days

Commitments and Contingencies_2

Commitments and Contingencies - Future minimum obligations (Details) $ in Thousands	Dec. 31, 2020USD ($)
Minimum obligations due under its license agreements
2021	$ 113
2022	113
2023	113
2024	113
2024	113
Thereafter	900
Total minimum license payments	$ 1,465

Commitments and Contingencies_3

Commitments and Contingencies - Purchase obligations (Details) $ in Thousands	Dec. 31, 2020USD ($)
Commitments and Contingencies.
2021	$ 2,295
2022	5,390
2023	6,285
2024	7,875
2025	8,199
Thereafter	17,925
Total minimum purchase commitments	$ 47,969

Commitments and Contingencies_4

Commitments and Contingencies - Guarantees and Indemnifications (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Indemnification obligations
Indemnification obligations	$ 0	$ 0

Defined Contribution Plan (Deta

Defined Contribution Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan
Matching contribution by employer	$ 446	$ 454

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Selected Quarterly Financial Data (Unaudited)
Product revenues, net	$ 2,238	$ 2,220	$ 833	$ 1,071	$ 1,180	$ 1,451	$ 2,057	$ 1,386	$ 6,362	$ 6,074
Total operating expenses	31,222	28,062	22,113	21,196	21,377	23,018	24,467	25,436	102,593	94,298
Total other income (expense)	(2,128)	(2,106)	(2,032)	(1,830)	(1,761)	(1,609)	(1,415)	(1,338)	(8,096)	(6,123)
Net loss	$ (31,112)	$ (27,948)	$ (23,312)	$ (21,955)	$ (21,958)	$ (23,176)	$ (23,825)	$ (25,388)	$ (104,327)	$ (94,347)
Net loss per share attributable to common stockholders-basic and diluted	$ (0.55)	$ (0.50)	$ (0.42)	$ (0.54)	$ (0.63)	$ (0.68)	$ (0.70)	$ (0.75)	$ (1.99)	$ (2.76)