Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2018	Mar. 12, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	TTPH
Entity Registrant Name	TETRAPHASE PHARMACEUTICALS INC
Entity Central Index Key	0001373707
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		53,745,497
Entity Public Float			$ 179,056,120
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 107,776	$ 136,411
Accounts receivable, net	2,274	4,653
Contract asset	3,000
Inventory	748
Prepaid expenses and other current assets	2,674	6,382
Total current assets	116,472	147,446
Property and equipment, net	1,121	1,395
Restricted cash	699	199
Intangible assets, net	4,652
Total assets	122,944	149,040
Current liabilities:
Accounts payable	3,210	5,306
Accrued expenses	11,747	12,559
Deferred revenue	6	660
Total current liabilities	14,963	18,525
Loan payable	28,291
Other long term liabilities	8	105
Commitments and contingencies (Note 10)
Stockholders' equity:
Preferred stock, par value $0.001 per share; 5,000 shares authorized; no shares issued and outstanding
Common stock, par value $0.001 per share; 125,000 shares authorized; 53,680 and 51,458 shares issued and outstanding at December 31, 2018 and 2017, respectively	53	51
Additional paid-in capital	613,671	592,243
Accumulated deficit	(534,042)	(461,884)
Total stockholders’ equity	79,682	130,410
Total liabilities and stockholders’ equity	$ 122,944	$ 149,040

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	53,680,000	51,458,000
Common stock, shares outstanding	53,680,000	51,458,000

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Total revenue	$ 18,904	$ 9,666
Expenses:
Research and development	54,879	101,706
Selling, general and administrative	37,078	23,675
Total expenses	92,185	125,381
Loss from operations	(73,281)	(115,715)
Other income and expenses
Interest income	1,747	963
Interest expense	(624)
Net loss	$ (72,158)	$ (114,752)
Net loss per share-basic and diluted	$ (1.37)	$ (2.63)
Weighted-average common shares used in net loss per share-basic and diluted	52,514	43,582
Comprehensive loss	$ (72,158)	$ (114,752)
Product Revenues, net [Member]
Revenues:
Total revenue	178
Expenses:
Cost of revenue	130
License and Collaboration Revenue [Member]
Revenues:
Total revenue	12,677
Government Revenue [Member]
Revenues:
Total revenue	6,049	$ 9,666
Intangible asset amortization [Member]
Expenses:
Cost of revenue	$ 98

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	"At-The-Market" Equity Offering Sales Agreement [Member]	Follow-On Public Offering [Member]	Common Shares [Member]	Common Shares [Member] "At-The-Market" Equity Offering Sales Agreement [Member]	Common Shares [Member] Follow-On Public Offering [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] "At-The-Market" Equity Offering Sales Agreement [Member]	Additional Paid-In Capital [Member] Follow-On Public Offering [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2016	$ 140,053			$ 37			$ 487,148			$ (347,132)
Beginning Balance, shares at Dec. 31, 2016				36,942,000
Issuance of common stock under stock plans	289						289
Issuance of common stock under stock plans, shares				173,000
Issuance of common stock from offering		$ 31,142	$ 61,394		$ 4	$ 10		$ 31,138	$ 61,384
Issuance of common stock from offering, shares					4,158,000	10,107,000
Issuance of common stock under employee stock purchase plan	321						321
Issuance of common stock under employee stock purchase plan, shares				78,000
Stock-based compensation expense	11,963						11,963
Net loss	(114,752)									(114,752)
Ending Balance at Dec. 31, 2017	130,410			$ 51			592,243			(461,884)
Ending Balance, shares at Dec. 31, 2017				51,458,000
Issuance of common stock under stock plans	$ 271						271
Issuance of common stock under stock plans, shares	115,064			184,000
Issuance of common stock from offering		$ 7,039			$ 2			$ 7,037
Issuance of common stock from offering, shares					1,952,000
Issuance of warrants to purchase common stock	$ 803						803
Issuance of common stock under employee stock purchase plan	188						188
Issuance of common stock under employee stock purchase plan, shares				86,000
Stock-based compensation expense	13,129						13,129
Net loss	(72,158)									(72,158)
Ending Balance at Dec. 31, 2018	$ 79,682			$ 53			$ 613,671			$ (534,042)
Ending Balance, shares at Dec. 31, 2018				53,680,000

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net loss	$ (72,158)	$ (114,752)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	576	431
Non-cash interest expense related to notes payable	145
Stock-based compensation expense	13,129	11,963
Changes in operating assets and liabilities:
Accounts receivable	2,379	(2,864)
Contract asset	(3,000)
Inventory	(748)
Prepaid expenses and other assets	3,708	200
Accounts payable	(2,096)	2,751
Accrued expenses and other liabilities	(909)	4,816
Deferred revenue	(654)	(595)
Net cash used in operating activities	(59,628)	(98,050)
Investing activities
Acquisition of intangible assets	(4,750)
Purchases of property and equipment	(204)	(771)
Net cash used in investing activities	(4,954)	(771)
Financing activities
Proceeds from sale of common stock, net of issuance costs	7,039	92,536
Proceeds from issuance of debt, net of issuance costs	28,949
Proceeds from issuance of stock under stock plans	459	610
Net cash provided by financing activities	36,447	93,146
Net increase (decrease) in cash, cash equivalents and restricted cash	(28,135)	(5,675)
Cash, cash equivalents and restricted cash at beginning of period	136,610	142,285
Cash, cash equivalents and restricted cash at end of period	108,475	$ 136,610
Supplemental cash flow information
Cash paid for interest	$ 480

Organization and Operations

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Operations

(1) Organization and Operations

The Company

Tetraphase Pharmaceuticals, Inc. (the “Company”) is a biopharmaceutical company using its proprietary chemistry technology to create, develop and commercialize novel tetracyclines for serious and life-threatening conditions, including bacterial infections caused by multidrug-resistant, or MDR, bacteria. The Company developed its lead product candidate, Xerava^TM (eravacycline), a fully synthetic fluorocycline, as an intravenous, or IV antibiotic for use as a first-line empiric monotherapy for the treatment of MDR infections, including MDR Gram-negative infections, such as those found in complicated intra-abdominal infections, or cIAI.

On August 27, 2018, the United States Food and Drug Administration, or FDA, approved Xerava for the treatment of cIAI in adults. Approval of Xerava was based on its IGNITE (Investigating Gram-Negative Infections Treated with Eravacycline) phase 3 program. In October 2018, the Company commenced sales of Xerava in the United States.

On September 20, 2018, based on the results of IGNITE1, the European Commission, or EC, granted marketing authorization for Xerava for the treatment of cIAI in adults in all 28 countries of the European Union, or EU, plus Norway, Iceland and Liechtenstein.

In addition to Xerava, the Company is pursuing development of TP-6076, a fully synthetic fluorocycline, targeted at unmet medical needs, including multidrug-resistant Gram-negative bacteria, and TP-271, a fully synthetic fluorocycline being developed for respiratory disease caused by bacterial biothreat pathogens and. Both of these programs are in phase 1. The Company is no longer developing eravacycline (IV or oral formulations) for the treatment of complicated urinary tract infections as a result of the clinical outcomes of IGNITE2 and IGNITE3. The Company does not intend to continue the development of TP-271 unless it secures additional non-dilutive funding for its development. The Company is also pursuing development of TP-2846, a tetracycline for the treatment of acute myeloid leukemia.

The Company has incurred annual net operating losses in every year since its inception. As of December 31, 2018, the Company had incurred losses since inception of $534.0 million. The Company has financed its operations primarily through the public offerings and private placements of equity securities, debt financings, revenue from United States government grants and contract awards and milestone payments from its licensing agreement. The Company will be required to obtain further funding through public or private equity offerings, debt financings, collaborations and licensing arrangements or other sources to fund our operations including ongoing spending to commercialize Xerava.

There can be no assurance that the Company will be able to obtain additional debt or equity financing or generate product revenue or revenues from collaborative partners, on terms acceptable to the Company, on a timely basis or at all. The failure of the Company to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the Company’s business, results of operations and financial condition.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

(2) Summary of Significant Accounting Policies

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment, which is the business of developing and commercializing its proprietary chemistry technology to create novel antibiotics for serious and life-threatening infections, including multidrug-resistant infections.

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles (”GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses, and related disclosures. On an ongoing basis, the Company’s management evaluates its estimates, including product revenue, inventory, estimates related to clinical trial accruals, stock-based compensation expense, contract and grant revenues, and going concern considerations. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.

Concentrations of Credit Risk and Off-Balance Sheet Risk

Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash, cash equivalents and restricted cash. The Company maintains its cash and cash equivalent balances in the form of cash and money market accounts with financial institutions that management believes are creditworthy. The Company’s investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimize its exposure to concentration of credit risk. The Company has no financial instruments with off-balance-sheet risk of loss.

The Company is also subject to credit risk on its accounts receivable, including from its trade customer receivables and contract receivables from CUBRC Inc. (“CUBRC”), an independent, not-for-profit, research corporation that specializes in U.S. government-based contracts, and the Combating Antibiotic Resistant Bacteria Biopharmaceutical Accelerator, or CARB-X, an international public-private partnership focused on advancing new antimicrobial products to address the threat of antibiotic resistance. The company has a strong track record of collection on its accounts receivable from both CUBRC and CARB-X.

The Company’s trade receivables from product sales have payment terms ranging from 30 to 60 days. The Company has evaluated the creditworthiness of its customers and has determined each of them to be creditworthy. The Company has not experienced any trade receivable losses to date.

Principles of Consolidation

The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.

Cash and Cash Equivalents

The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents. Cash and cash equivalents at December 31, 2018 and 2017 consisted of cash and money market funds.

Fair Value Measurements

The Company’s financial instruments consist principally of cash and cash equivalents, accounts receivable, accounts payable, and accrued liabilities. Fair value measurements are classified and disclosed in one of the following three categories:

Level 1 — Quoted prices in active markets for identical assets or liabilities.

Level 2 — Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Financial instruments measured at fair value as of December 31, 2018 and 2017 are classified below based on the three fair value hierarchy tiers described above (in thousands):

			Fair Value Measurements at Reporting Date Using
	Balance		Level 1		Level 2		Level 3
December 31, 2018
Cash and money market funds	$	107,776	$	107,776	$	—	$	—
December 31, 2017
Cash and money market funds	$	136,411	$	136,411	$	—	$	—

The Company measures cash equivalents at fair value on a recurring basis. The fair value of cash equivalents is determined based on “Level 1” inputs, which consist of quoted prices in active markets for identical assets.

Accounts Receivable

Accounts receivable at December 31, 2018 and 2017 represent amounts due from two main sources: (1) Trade accounts receivable of $0.1 million consisting of payments to be received from customers for sales of Xerava, net of prompt payment discounts, chargebacks, rebates and certain fees and (2) contract accounts receivable of $2.2 million related to the Company’s government-related agreements.

Contract accounts receivable relate to payments from entities administering the Company’s government-related agreements which include unbilled contract accounts receivable of $0.7 million and $2.4 million at December 31, 2018 and 2017, respectively.

Contract Balances

The Company recognizes a contract asset when the Company transfers goods or services to a customer before the customer pays consideration or before payment is due, excluding any amounts presented as a receivable (i.e. accounts receivable). A contract asset represents the Company’s right to consideration in exchange for goods or services that the Company has transferred to a customer.

As of December 31, 2018, such contract assets were $3.0 million in relation to milestone payments to be received under the terms of the Everest Medicines License Agreement. For the twelve-month period ended December 31, 2018, the Company recognized license revenue included in such contract assets of $3.0 million. See Note 3 for further details.

Inventory

Inventory is stated at the lower of cost or net realizable value on a first-in, first-out (FIFO) basis. Prior to the regulatory approval of Xerava, given the uncertainty of approval, the Company recognized as research and development expense costs related to the manufacture of Xerava. Upon approval of Xerava, the Company began to capitalize such costs as inventory.

During each quarter, the Company performs an assessment quantifying any potential excess or obsolete inventory and writes down any such inventory to its net realizable value in the period in which the impairment is identified. These adjustments are based upon multiple factors, including inventory levels at the company and at its specialty distributors, projected demand and product shelf life. These impairment charges, if required, are recorded as a cost of revenue. As of December 31, 2018, estimates of excess inventory were immaterial.

Property and Equipment, Net

Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation and amortization are recognized using the straight-line method over the estimated useful lives of the respective assets, which is generally three to five years. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful economic lives of the related assets.

Restricted Cash

At December 31, 2018 the Company had $699,000 in restricted cash deposits with a bank, of which $500,000 is serving as security for our field force corporate credit card program. $159,000 is collateral for a letter of credit issued to the landlord of the Company’s leased facility. If the Company defaults on its rental obligations, $159,000 will be payable to the landlord. In addition, the Company has $40,000 in restricted cash to secure the Company’s corporate purchasing credit card issued through the same bank.

Intangible Assets

The Company maintains definite-lived intangible assets related to certain capitalized milestone payments to Harvard University (Harvard). These assets are amortized over their remaining useful lives, which are estimated based on the shorter of the remaining patent life or the estimated useful life of the underlying product. Intangible assets are amortized using the economic consumption method if anticipated future revenues can be reasonably estimated. The straight-line method is used when future revenues cannot be reasonably estimated.

The Company assesses its intangible assets for impairment if indicators are present or changes in circumstance suggest that impairment may exist. Events that could result in an impairment, or trigger an interim impairment assessment, include the receipt of additional clinical or nonclinical data regarding one of the Company’s drug candidates or a potentially competitive drug candidate, changes in the clinical development program for a drug candidate, or new information regarding potential sales for the drug. If impairment indicators are present or changes in circumstance suggest that impairment may exist, the Company performs a recoverability test by comparing the sum of the estimated undiscounted cash flows of each intangible asset to its carrying value on the consolidated balance sheet. If the undiscounted cash flows used in the recoverability test are less than the carrying value, the Company would determine the fair value of the intangible asset and recognize an impairment loss if the carrying value of the intangible asset exceeds its fair value.

The Company capitalized milestone payments of $4.75 million related to regulatory approval of Xerava in the US and EU, which will be amortized over their estimated useful lives of approximately 12 years. Amortization expense for each of the following five years is expected to be $0.4 million.

Revenue Recognition

Product Revenue

Revenue recognition under ASC 606 is applied through a five-step model as follows: (1) identify the contract(s) with the customer; (2) identify performance obligations in the contract; (3) determine the transaction price; (4) allocate transaction price to the performance obligation; and (5) recognize revenue when (or as) each performance obligation is satisfied.

The Company’s arrangements with its distributors are determined to be contracts within the scope of ASC 606 when all five criteria in ASC 606 are met. These five criteria were assessed at the inception of each arrangement. Since the criteria were met during this initial assessment, the Company will not reassess the criteria unless there is an indication of a significant change in facts and circumstances. In order to meet the definition of a contract, it must also be probable that the Company will collect the consideration to which it is entitled for goods or services to be transferred. Once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services to be delivered with each contract, determines whether those are performance obligations and the related transaction price. The Company then recognizes revenue based on the transaction price that is allocated to the respective performance obligation when the performance obligation is satisfied.

The Company’s product revenue consists of the sales of Xerava, which the Company began selling to customers in October 2018. The Company sells Xerava to specialty distributors. These customers resell Xerava to hospitals or other treatment centers. In addition to these distributor agreements and the related discounts and allowances, the Company is subject to government mandated rebates, chargebacks, and discounts with respect to the purchase of the Company’s product. Product revenue is recognized net of reserves for all variable consideration, including discounts, chargebacks, government rebates and product returns. The Company is expensing the costs of obtaining and fulfilling these contracts when incurred. The Company has opted to immediately expense the incremental cost of obtaining a contract when the underlying related asset would have been amortized over one year or less.

Reserves for Variable Consideration

The Company evaluates its contracts with customers for forms of variable consideration which may require an adjustment to the transaction price based on their estimated impact. Revenues from product sales are recorded at the gross sales price, net of variable consideration, as described above.

The Company estimates variable consideration using the expected value method, which is the sum of probability-weighted amounts in a range of possible outcomes. These outcomes include market events and trends, forecasted product demand patterns, customer buying patterns and statutory requirements. The resulting reserves represent the Company’s best estimates of variable consideration it expects to occur.

Before it can include an amount of variable consideration in the transaction price, the Company must consider whether the amount of variable consideration is constrained. The Company includes estimates of variable consideration in revenue only when it has a “high degree of confidence” that revenue will not be reversed in a subsequent reporting period. To include variable consideration in the estimated transaction price, the entity has to conclude that it is “probable” that a significant revenue reversal will not occur in future periods, considering both the likelihood and magnitude of a revenue reversal to apply the constraint. Based on the above, the Company applies the constraint to variable consideration included in its contracts if it cannot conclude that it is probable that a significant revenue reversal will not occur in future periods.

Trade Discounts and Allowances: The Company offers its customers prompt pay discounts and service fees as stated in its customer contracts. The Company pays these service fees to its customers in exchange for their performance of various product distribution, marketing and promotional services targeted at advancing end-user sales of the Company’s product. The related reserves are set in the same period the corresponding revenue is recognized, resulting in a reduction of product revenue.

Government Chargebacks and Rebates: Under the terms of the Company’s master agreements, customers may charge back the Company for reimbursement when they are contractually obligated to sell products to government entities or other end-users at a lower price than the wholesale acquisition cost, or WAC, at which those products were acquired from the Company. These rebates consist of Medicare, TriCare and Medicaid rebates as well as those related to other government drug pricing and reimbursement programs.

Product Returns: Products are eligible for return by the Customers in various scenarios under the Company’s returns policies included as part of its master distribution agreements. Return options are provided for expired merchandise, short-dated merchandise, products damaged in transit, or any discontinued, withdrawn, or recalled products. The Company estimates the amount of product that may be returned and records this as a reduction in revenue in the relevant period. The Company currently estimates product return liabilities using available industry data, sales information and visibility into the inventory remaining in the distribution channel. The Company has not received any returns to date since launch.

The Company will continue to assess its estimates of the various components of variable consideration as it accumulates additional historical data and make adjustments to these estimates and allowances accordingly.

Collaboration Revenue

The Company has entered into an out-licensing agreement that is evaluated under Accounting Standards Codification, Topic 606 (“Topic 606”), Revenue from Contracts with Customers, through which the Company licenses certain of its product candidates’ rights to a third party. Any future out-licensing agreements entered into by the Company and additional third parties shall also be evaluated under Topic 606. Terms of these arrangements include various payment types, typically including one or more of the following: upfront license fees; development, regulatory and commercial milestone payments; payments for manufacturing supply services; and/or royalties on net sales of licensed products.

To determine the amount and timing of revenue to be recognized under each agreement, the Company evaluates the following criteria: (i) confirming the goods or services in the contract; (ii) defining the performance obligations under the agreement; (iii) determining the transaction price, including any constraint on variable consideration; (iv) allocating the transaction price to the performance obligations; and (v) defining how the revenue will be recognized for each performance obligation. In determining the accounting treatment for these arrangements, the Company develops assumptions to determine the stand-alone selling price for each performance obligation in the contract. These assumptions may include forecasted revenues, development timelines, discount rates and probabilities of technical and regulatory success.

Licenses of Intellectual Property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from upfront fees allocated to the license when the license, including any associated know-how, is transferred to the licensee and the licensee can use and benefit from the license. For licenses that are bundled with other obligations, the Company uses judgment to evaluate the combined performance obligation to determine whether it is satisfied over time or at a point in time and the appropriate method of measuring completion for purposes of recognizing revenue.

Milestone Payments: For arrangements that include development milestone payments, the Company evaluates whether the milestones are considered probable and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are not considered probable of being achieved until those approvals are received.

Manufacturing Supply: Arrangements that include a promise for future supply of drug substance or drug product for either clinical development or commercial supply at the licensee’s discretion are generally considered as options. The Company assesses if these options provide a material right to the licensee and if so, they are accounted for as separate performance obligations. If the Company is entitled to additional payments when the licensee exercises these options, the Company recognizes revenue when the licensee obtains control of the goods, which is upon delivery.

Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

Government Contract Revenue

The Company’s government contract revenue has been derived from its subcontracts with CUBRC under the BARDA Contract, and the NIAID Contract, its subaward under the NIAID Grant and its cost reimbursement Sub-Award Agreement with the Trustees of Boston University, the administrator of the CARB-X program (Note 3). The Company recognizes revenue under these best-efforts, cost-reimbursable and cost-plus-fixed-fee subcontracts and subaward as the Company performs services under the subcontracts and subaward so long as a subcontract and subaward has been executed and the fees for these services are fixed or determinable, legally billable and reasonably assured of collection. Recognized amounts reflect the Company’s partial performance under the subcontracts and subaward and equal direct and indirect costs incurred plus fixed fees, where applicable. The Company does not recognize revenue under these arrangements for amounts related to contract periods where funding is not yet committed as amounts above committed funding thresholds would not be considered fixed or determinable or reasonably assured of collection. Revenues and expenses under these arrangements are presented gross on the consolidated statements of operations and comprehensive loss as the Company has determined it is the primary obligor under these arrangements relative to the research and development services it performs as lead technical expert.

Revenue under the Company’s subcontracts under both the NIAID Contract and the BARDA Contract and under the CARB-X Award are earned under a cost-plus-fixed-fee arrangement in which the Company is reimbursed for direct costs incurred plus allowable indirect costs and a fixed-fee earned. Billings under these arrangements are based on approved provisional indirect billing rates, which permit recovery of allowable fringe benefits, allowable overhead and general and administrative expenses and a fixed fee.

Revenue under the Company’s subaward under the NIAID Grant was earned under a cost-reimbursable arrangement in which the Company was reimbursed for direct costs incurred plus allowable indirect costs. Billings under the NIAID Grant are based on approved provisional indirect billing rates, which permit recovery of fringe benefits and allowable general and administrative expenses.

Cost of Revenue

Cost of revenue consists primarily of the manufacturing and distribution costs for Xerava, Xerava net sales-based royalties and the amortization of the intangible asset associated with certain milestones paid to Harvard related to Xerava. All manufacturing costs incurred prior to Xerava’s approval in the United States on August 27, 2018 have been expensed in research and development and are not included in cost of revenue.

Research and Development Expenses

Research and development costs are charged to expense as incurred and include, but are not limited to:

•

personnel-related expenses, including salaries, benefits, and stock-based compensation expense;

•

expenses incurred under agreements with contract research organizations, contract manufacturing organizations and consultants that provide preclinical, clinical, regulatory and manufacturing services;

•

certain payments made under the Company’s license agreement with Harvard University;

•

the cost of acquiring, developing and manufacturing clinical trial materials and lab supplies;

•

facility, depreciation and other expenses, which include direct and allocated expenses for rent, maintenance of the Company’s facilities, insurance and other supplies; and

•

costs associated with preclinical and regulatory.

Costs for certain development activities, such as clinical trials, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the financial statements as prepaid or accrued research and development. In certain circumstances, the Company is required to make nonrefundable advance payments to vendors for goods or services that will be received in the future for use in research and development activities. In such circumstances, the nonrefundable advance payments are deferred and capitalized, even when there is no alternative future use for the research and development, until related goods or services are provided.

Comprehensive Loss

Comprehensive loss consists of net income or loss and changes in equity during a period from transactions and other events and circumstances generated from non-owner sources. The Company’s net loss equals comprehensive loss for all periods presented.

Income Taxes

The Company uses the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial reporting and the tax reporting basis of assets and liabilities and are measured using the enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax assets will be realized. The Company has evaluated available evidence and concluded that the Company may not realize the benefit of its deferred tax assets; therefore a valuation allowance has been established for the full amount of the deferred tax assets. The Company’s practice is to recognize interest and/or penalties related to income tax matters in income tax expense.

The Tax Cuts and Jobs Act (“the Act”) was enacted on December 22, 2017. The Act reduces the US federal corporate tax rate from 34% to 21%, requires companies to pay a one-time transition tax on earnings of certain foreign subsidiaries that were previously tax deferred and creates new taxes on certain foreign sourced earnings. On December 22, 2017, the Securities and Exchange Commission issued guidance under Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (“SAB 118”) directing taxpayers to consider the impact of the U.S. legislation as “provisional” when it does not have the necessary information available, prepared or analyzed (including computations) in reasonable detail to complete its accounting for the change in tax law.

At December 31, 2018, the accounting for the tax effects of enactment of the Act was completed and did not recognize any material adjustments from the provisional amounts that were recorded.

Stock-Based Compensation

The Company determines stock-based compensation at the grant date using the Black-Scholes option pricing model to estimate fair value for employee equity awards. The Company recognizes the value of the award as an expense on a straight-line basis over the requisite service period using the estimated fair market value of the stock and accounts for forfeitures as they occur. For employee awards with performance conditions, the Company assesses whether the condition is probable of achievement, in which case, the fair value of the award is recognized over the requisite service period. The Company records stock-based compensation expense for payments issued to non-employees based on the fair value of the awards using the Black-Scholes option pricing model. Stock-based compensation payments issued to non-employees are revalued at each reporting period and as the equity instruments vest and are recognized as expense using the accelerated attribution method over the related service period.

Going Concern Assessment

Accounting Standards Update (“ASU”) No. 2014-15, Presentation of Financial Statements - Going Concern, requires management to evaluate the company’s ability to continue as a going concern one year beyond the filing date of the given financial statements. This evaluation requires management to perform two steps. First, management must evaluate whether there are conditions and events that raise substantial doubt about the entity’s ability to continue as a going concern. Second, if management concludes that substantial doubt is raised, management is required to consider whether it has plans in place to alleviate that doubt. Disclosures in the notes to the financial statements are required if management concludes that substantial doubt exists or that its plans alleviate the substantial doubt that was raised.

Based on a detailed cash forecast incorporating Xerava commercialization activities, selective development of its pipeline candidates and related spending plans, the Company expects its cash to last more than one year beyond the date that the financial statements were issued. Management’s belief with respect to its ability to fund operations is based on estimates that are subject to risks and uncertainties. If actual results are different from management’s estimates, the Company may need to seek additional funding sooner than anticipated. Based on this analysis, no additional disclosures were required.

Recently Adopted Accounting Pronouncements

In November 2016, the Financial Accounting Standard Board (FASB) issued Accounting Standards Update No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (ASU 2016-18), which requires companies to include amounts generally described as restricted cash and restricted cash equivalents in cash and cash equivalents when reconciling beginning-of-period and end-of-period total amounts shown on the statements of cash flows. The Company adopted the new standard effective January 1, 2018, using the retrospective transition approach. The reclassified restricted cash balances from operating activities to changes in cash, cash equivalents and restricted cash on the condensed consolidated statements of cash flows were not material for all periods presented.

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which delayed the effective date of the new standard from January 1, 2017 to January 1, 2018. The FASB also agreed to allow entities to choose to adopt the standard as of the original effective date. The FASB has subsequently issued ASU 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net); ASU 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing; ASU 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients; and ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers. The Company adopted this standard retrospectively to all periods presented.

In addition to its evaluation of its product and collaboration revenue under Topic 606 as discussed above, the Company has concluded that its government grants are not within the scope of Topic 606, as they do not meet the definition of a contract with a “customer”. The Company has concluded that the grants meet the definition of a contribution and are non-reciprocal transactions. The Company has further concluded that Subtopic 958-605, Not-for-Profit-Entities-Revenue Recognition also does not apply, as the Company is a business entity and the grants are with governmental agencies or units. The government grant is technically to a non-profit entity that specializes in government grant administration, project management and oversight (i.e. CUBRC). However, the Company has concluded that, in effect, it is a grant from the government; as the contracting counterparty CUBRC is merely administering the agreement between the government (who is funding the work) and the Company (who is performing the work).

In the absence of applicable guidance under GAAP as of January 1, 2018 for the grants, the Company has developed a policy for the recognition of revenue for the grants as follows:

•

Revenue is recognized when the right to payment is realized or is realizable

•

Revenues are realized when services are exchanged for cash or claims to cash. Revenues are not recognized until earned.

•

The Company’s revenue-earning activities involve rendering services that constitute its ongoing major or central operations, and revenues are considered to have been earned when the Company has substantially accomplished what it must do to be entitled to the benefits represented by the revenues.

The Company believes this policy is consistent with the overarching premise in Topic 606, to ensure that it recognizes revenues to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services, even though there is no “exchange” as defined in the ASC. The Company believes the recognition of revenue as costs are incurred and amounts become earned/realizable is analogous to the concept of transfer of control of a service over time under ASC 606.

Prior to January 1, 2018, the Company recognized revenue as it performed services under the grants so long as an agreement had been executed and the fees for these services were fixed or determinable, legally billable and reasonably assured of collection. Recognized amounts reflected the Company’s partial performance under the grants and equal direct and indirect costs incurred plus fixed fees, where applicable. Revenues and expenses under these arrangements were presented gross. Revenue recognition under this new policy is not materially different than would have been calculated under the old guidance. As a result of the adoption of this policy, there was no change to the amounts the Company has historically recorded to its financial statements.

There have been no other significant changes to the Company’s significant accounting policies since the beginning of this fiscal year.

Recent Accounting Pronouncements Not Yet Adopted

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The new standard requires that all lessees recognize the assets and liabilities that arise from leases on the balance sheet and disclose qualitative and quantitative information about its leasing arrangements. The new standard will be effective for the Company on January 1, 2019. The FASB subsequently issued the following amendments to ASU 2016-02, which have the same effective date and transition date of January 1, 2019: ASU No. 2018-10, Codification Improvements to Topic 842, Leases, which amends certain narrow aspects of the guidance issued in ASU 2016-02 and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, which allows for a transition approach to initially apply ASU 2016-02 at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption as well as an additional practical expedient for lessors to not separate non-lease components from the associated lease component.

The Company intends to adopt the standard at the effective date of January 1, 2019 by applying the new lease requirements beginning on the effective date without restating prior periods. Upon adoption, the Company plans to elect the package of practical expedients permitted under the transition guidance which, among other things, allows the Company to carry forward historical classification of its existing leases. While the Company is continuing to evaluate the impact of adopting the standard and its related amendments, the Company expects that the standard will result in recognition of material right-of-use assets and lease liabilities on the Company’s consolidated balance sheet. The Company is currently implementing controls and processes to address the future financial presentation and disclosure requirements of the standard.

Subsequent Events

The Company has considered all events occurring subsequent to December 31, 2018 and has concluded that all significant events have been disclosed in the financial statements and accompanying notes.

Net Loss per Common Share

Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of Common Stock outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing the net loss by the weighted average number of common share equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, warrants, stock options, and restricted stock units are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive.

The amounts in the table below were excluded from the calculation of diluted weighted-average shares outstanding, prior to the use of the treasury stock method, due to their anti-dilutive effect:

	Year Ended December 31,
	2018		2017
Warrants		414,365		—
Outstanding stock options		7,322,436		5,997,794
Unvested restricted stock units		1,080,440		282,034
Total		8,817,241		6,279,828

Significant Agreements and Contracts

12 Months Ended

Dec. 31, 2018

Research And Development [Abstract]

Significant Agreements and Contracts

(3) Significant Agreements and Contracts

License Agreement

In August 2006, the Company entered into a license agreement for certain intellectual property with Harvard University. Under the license agreement, as of December 31, 2018, the Company has paid Harvard an aggregate of $15.8 million in upfront license fees, sublicense fees and development milestone payments for the licensed Harvard technology, and has issued 31,379 shares of common stock to Harvard.

For each product covered by the license agreement, the Company is obligated to make certain payments totaling up to approximately $15.1 million upon achievement of certain development and regulatory milestones and to pay additional royalties on net sales of such product. In January 2007 and April 2010, the Company and the University amended the license agreement to include certain additional intellectual property. The Company paid an additional $25,000 to the University with each amendment. In February 2011, the license agreement was further amended to include additional intellectual property in the license granted by the University without the payment of any additional consideration. The license agreement was further amended in December 2017 to change certain payments due to Harvard. For the years ended December 31, 2018 and 2017, the company paid Harvard $7.8 million and $1.8 million, respectively, in regulatory milestone payments.

Other Material Agreements

Everest Medicines License Agreement

In February 2018, the Company entered into a license agreement (the “Everest License Agreement”) with Everest Medicines Limited (“Everest Medicines”), whereby the Company granted Everest Medicines an exclusive license to develop and commercialize eravacycline, for the treatment of complicated intra-abdominal infections and other indications, in mainland China, Taiwan, Hong Kong, Macau, South Korea and Singapore (the “Territory”).

Under the terms of the Everest License Agreement, the Company received from Everest Medicines an upfront cash payment of $7.0 million in the first quarter of 2018 and a cash payment of $2.5 million related to Everest Medicines’ submission of an Investigational New Drug Application, or IND, with the Chinese Food and Drug Administration in June 2018. In 2019, the Company expects to receive an additional cash payment of $3.0 million related to Everest Medicine’s initiation of a Phase 3 clinical trial. The Company has determined that it is probable that this milestone will be achieved and that a significant revenue reversal will not occur, based on the Chinese FDA having furnished to Everest Medicines an IND approval letter to initiate a Phase 3 clinical trial in October 2018.

The Company is also eligible to receive up to an aggregate of $11.0 million in future clinical development milestone payments and up to an aggregate of $20.0 million in sales milestone payments. There can be no guarantee that any such milestones or sales thresholds will in fact be met. The Company is obligated to make certain payments to Harvard based on amounts received from Everest Medicines under the Everest License Agreement pursuant to the existing license agreement by and between Harvard and the Company.

The Company will also be entitled to receive low double-digit tiered royalties on sales in the Territory, if any, of products containing eravacycline. Royalties are payable with respect to each jurisdiction in the Territory until the latest to occur of: (i) the last-to-expire of specified patent rights in such jurisdiction in the Territory; (ii) expiration of marketing or regulatory exclusivity in such jurisdiction in the Territory; or (iii) ten (10) years after the first commercial sale of a product in such jurisdiction in the Territory. In addition, royalties payable under the Everest License Agreement will be subject to reduction on account of generic competition and after patent expiry in a jurisdiction if required by applicable law, with any such reductions capped at certain percentages of the amounts otherwise payable during the applicable royalty payment period.

Under the terms and conditions of the Everest License Agreement, Everest Medicines will be solely responsible for the development and commercialization of licensed products in the Territory. The Company agreed to manufacture clinical material, which will be paid by Everest at the Company’s cost, as well as commercial supply, which will be paid by Everest at cost plus a reasonable margin.

In evaluating the recognition of revenue under the Agreement, the Company identified the following three performance obligations under the Agreement: (i) exclusive license to develop and commercialize eravacycline for the treatment of complicated intra-abdominal infections and other potential, future indications, in the Territory, (ii) provision of information and technical assistance related to the know-how transfer for the development of eravacycline; and (iii) provision of clinical supply to Everest Medicines.

The Company evaluated the Everest License Agreement under Topic 606 at the time of execution of the arrangement. Based on that evaluation, the upfront fee of $7.0 million represented the amount of the consideration to be included in the transaction price, which was allocated to the identified performance obligations. Subsequent to execution, the Company determined that the milestones for the Chinese IND and Phase 3 clinical trial were probable to be achieved and that a significant revenue reversal would not occur, and included the payment amounts of $2.5 and $3.0 million, respectively, in the transaction price.

No other clinical milestones, regulatory milestones, sales-based milestones or sales royalties have been included in the transaction price, as these milestones were not considered probable at execution or each reporting period thereafter given Everest Medicines relatively short operating history, the uncertainty of regulatory processes in China and that commercial sales have not commenced. The Company determined that the license and related know-how were a combined performance obligation as the license is not distinct without the provision of the related know-how transfer. The Company’s requirement to manufacture clinical supply for Everest Medicines is dependent on Everest Medicines’ future purchases, the payment for which was determined to be at cost and therefore potentially represents a material right. However, based on the amount of clinical supply expected to be ordered by Everest Medicines, the Company estimated that the value of this right was immaterial.

The Company satisfied all performance obligations during 2018, therefore recognizing $12.7 million in license and collaboration revenue.

Patheon UK Limited Master Manufacturing Services Agreement

In June 2017, the Company and Patheon UK Limited and certain of its affiliates (“Patheon”) entered into a master manufacturing services agreement. Under the Patheon agreement, the Company is responsible for supplying the active pharmaceutical ingredient for eravacycline to Patheon, and Patheon is responsible for manufacturing eravacycline, conducting quality control, quality assurance, analytical testing and stability testing and packaging. The Company and Patheon entered into two related product agreements pursuant to the Patheon agreement that govern the terms and conditions of Patheon’s manufacture of commercial supplies of eravacycline at Patheon’s Greenville, North Carolina and Ferentino, Italy manufacturing sites. Pursuant to the Patheon agreement, the Company has agreed to order from Patheon at least a certain percentage of its annual commercial requirements for eravacycline in the United States and European Union each year for the term of the Patheon agreement. The Patheon agreement has an initial term ending December 31, 2022, and will automatically renew after the initial term for successive terms of two years each, unless either party gives notice of its intention to terminate at least 18 months prior to the end of the then current term. The Company may terminate a product agreement upon 30 days’ prior written notice under certain circumstances.

Finorga SAS Commercial Supply Agreement

In October 2017, the Company and Finorga SAS (“Novasep”) entered into a commercial supply agreement. Under the agreement, Novasep will, pursuant to accepted purchase orders entered into under the agreement, manufacture for commercial supply the active pharmaceutical ingredient for eravacycline. This agreement has an initial term ending October 16, 2022, and will automatically renew after the initial term, unless either party gives notice of its intention to terminate at least 18 months prior to the end of the then current term. The Company may terminate the Novasep agreement upon 30 days’ prior written notice under certain circumstances.

Government Grant and Contracts

BARDA Contract for Eravacycline

The Company has received funding for its lead product candidate, eravacycline, under an award to CUBRC from BARDA. In January 2012, BARDA awarded a five-year contract that provides for up to a total of $67.3 million in funding for the development, manufacturing and clinical evaluation of eravacycline for the treatment of disease caused by bacterial biothreat pathogens. The funding under the BARDA Contract is also being used for the development, manufacturing and clinical evaluation of eravacycline to treat certain infections caused by life-threatening multidrug-resistant bacteria.

In connection with the BARDA Contract, in February 2012, the Company entered into a cost-plus-fixed-fee subcontract with CUBRC which currently expires on March 30, 2019 under which the Company may receive funding of up to approximately $41.8 million, reflecting the portion of the BARDA Contract funding that may be paid to the Company for its activities.

Although the BARDA Contract and the Company’s subcontract with CUBRC under the BARDA Contract have terms which currently expire on March 30, 2019, BARDA is entitled to terminate the project for convenience at any time, and is not obligated to provide continued funding beyond current-year amounts from Congressionally approved annual appropriations. To the extent that BARDA ceases to provide funding of the program to CUBRC, CUBRC has the right to cease providing funding to the Company. Committed funding from CUBRC under the Company’s BARDA subcontract is up to $41.8 million through March 30, 2019, the current contract end date, as a result of the exercise of several options by BARDA under the BARDA Contract. Total funds of $39.6 million had been received by the Company through December 31, 2018 under this contract. During the years ended December 31, 2018 and 2017, the Company recognized revenue of $1.5 million and $5.5 million, respectively, from the Company’s subcontract under the BARDA Contract.

NIAID Grant and Contract for TP-271

The Company has received funding for its preclinical compound TP-271 under two awards to CUBRC from NIAID for the development, manufacturing, and clinical evaluation of TP-271 for respiratory diseases caused by biothreat and antibiotic-resistant public health pathogens, as well as bacterial pathogens associated with community-acquired bacterial pneumonia:

•

the NIAID Grant awarded in July 2011 that provided up to a total of approximately $2.9 million over five years; and

•

the NIAID Contract awarded in September 2011 that provides up to a total of approximately $35.8 million in funding over five years.

In connection with the NIAID Grant, in November 2011, CUBRC awarded the Company a no-fee subaward of approximately $0.9 million, reflecting the portion of the NIAID Grant funding that may be paid to the Company for its activities. Through December 31, 2018, the Company had received all committed funding of $0.9 million from CUBRC under the Company’s subaward with respect to the NIAID Grant.

In connection with the NIAID Contract, in October 2011, the Company entered into a cost-plus-fixed-fee subcontract with CUBRC which currently expires on March 31, 2019 under which the Company may receive funding of up to approximately $16.9 million, reflecting the portion of the NIAID Contract funding that may be paid to the Company for its activities.

Although the NIAID Contract and the Company’s subcontract with CUBRC under the NIAID Contract have terms which currently expire on March 31, 2019. NIAID is entitled to terminate the project for convenience at any time, and is not obligated to provide continued funding beyond the respective expiration dates. To the extent that NIAID ceases to provide funding of the programs to CUBRC, CUBRC has the right to cease providing funding to the Company. As of December 31, 2018, committed funding from CUBRC under the Company’s subcontract with respect to the NIAID Contract is $16.6 million, of which $15.7 million had been received through December 31, 2018.

During the years ended December 31, 2018 and 2017, the Company recognized revenue of $2.5 million and $3.5 million, respectively, from the Company’s subcontract under the NIAID Contract. During the year ended December 31, 2017 the Company recognized $9,000 from the Company’s subaward under the NIAID Grant.

CARB-X Award for TP-6076

In March 2017, CARB-X selected the Company to receive up to $4.0 million in research funding over eighteen months for TP-6076. In connection with this funding, the Company entered into a cost reimbursement Sub-Award Agreement (the “Sub-Award Agreement”) with the Trustees of Boston University, the administrator of the program. The Company began recognizing revenue from the Sub-Award Agreement in April 2017. During the years ended December 31, 2018 and 2017, the Company recognized revenue of $2.0 million and $0.7 million, respectively, under this Sub-Award Agreement. Although this Sub-Award Agreement expired by its terms on December 31, 2018, we expect to reach an agreement with CARB-X to extend the performance date out to June 30, 2019 (pending an amendment that would take the performance date out to June 30, 2019, the project can be terminated for convenience at any time, subject to 30 days prior written notice.

Property and Equipment

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Property and Equipment

(4) Property and Equipment

Property and equipment at December 31, 2018 and 2017 consisted of the following (in thousands):

	Estimated		December 31,
	Useful Life In Years		2018			2017
Laboratory equipment		5	$	3,278		$	3,101
Furniture and fixtures		5		509			509
Office and computer equipment		3		217			208
Leasehold improvements				923			923
Property and equipment, gross				4,927			4,741
Less accumulated depreciation and amortization				(3,806	)		(3,346	)
Property and equipment, net			$	1,121		$	1,395

Depreciation and amortization expense related to property and equipment for the years ended December 31, 2018, 2017 was $479,000 and $431,000 , respectively.

Accrued Expenses

12 Months Ended

Dec. 31, 2018

Payables And Accruals [Abstract]

Accrued Expenses

(5) Accrued Expenses

Accrued expenses at December 31, 2018 and 2017 consisted of the following (in thousands):

	December 31, 2018		December 31, 2017
Drug supply and development	$	3,901	$	2,298
Salaries and benefits		3,801		4,137
Professional fees		1,178		1,911
Commercial		910		—
License payments		617		—
Clinical trial related		146		3,401
Other		1,194		812
Total	$	11,747	$	12,559

Stockholders' Equity

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Stockholders' Equity

(6) Stockholders’ Equity

In January 2017, the Company entered into a Controlled Equity Offering Sales Agreement (the “Sales Agreement”), with Cantor Fitzgerald & Co. as sales agent (“Cantor”). In July 2017, the Company entered into an amendment to the Sales Agreement to increase the maximum aggregate offering price of the shares of common stock that it may issue and sell from time to time under the Sales Agreement from $40,000,000 to $80,000,000.

Under the Sales Agreement, as amended (the “Amended Sales Agreement”), Cantor may sell shares of the Company’s common stock by methods deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended, including sales made directly on The Nasdaq Global Select Market or on any other existing trading market for the Company’s common stock.

The Company is not obligated to make any sales of shares of its common stock under the Amended Sales Agreement. The Company or Cantor may suspend or terminate the offering of shares of the Company’s common stock upon notice to the other party and subject to other conditions. The Company pays Cantor a commission rate equal to 3.0% of the gross proceeds per share sold.

As of December 31, 2018, the Company had sold an aggregate of 6,110,446 shares of common stock under the Sales Agreement, at an average selling price of approximately $6.49 per share for aggregate gross proceeds of $39.6 million and net proceeds of $38.2 million after deducting the sales commissions and offering expenses. As of March 13, 2019, $40.4 million of common stock remained available to be sold under the Amended Sales Agreement, subject to certain conditions specified therein.

On August 2, 2017, the Company sold 10,000,000 shares of common stock in an underwritten public offering at an offering price to the public of $6.50 per share, resulting in net proceeds to the Company of $60.7 million after deducting underwriting discounts and commissions of $3.9 million and offering costs of $0.4 million. In connection with the offering, the Company granted the underwriters an option to purchase up to an additional 1,500,000 shares on the same terms and conditions as the offering, pursuant to which the underwriters exercised an option to purchase 107,000 additional shares on August 25, 2017, resulting in additional net proceeds to the Company of approximately $0.7 million after deducting underwriting discounts and commissions.

Stock-based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-based Compensation

(7) Stock-based Compensation

In February 2013, the Company’s board of directors and stockholders approved, effective upon the closing of the IPO, the 2013 Stock Incentive Plan (the “2013 Plan”). Under the 2013 Plan, the Company may grant incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards for the purchase of that number of shares of Common Stock equal to the sum of (i) 1,688,777 shares of Common Stock, (ii) 258,265 shares of Common Stock that were reserved for issuance under the 2006 Plan that remained available for issuance under the 2006 Plan upon the closing of the IPO, (iii) any shares of Common Stock subject to awards under the 2006 Plan which awards expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by the Company without having been fully exercised or resulting in any Common Stock being issued. In addition, the number of shares of Common Stock that may be issued under the 2013 Plan is subject to automatic annual increases, to be added on January 1 of each year from January 1, 2014 through and including January 1, 2023, equal to the number of shares that is the lesser of (a) 3,000,000, (b) 4% of the then outstanding shares of Common Stock or (c) an amount determined by the Company’s board of directors.. In January 2019, the number of shares authorized for issuance under the 2013 Plan increased by 2,147,192 shares.

Terms of stock award agreements, including vesting requirements, are determined by the board of directors, subject to the provisions of the 2013 Plan. Options granted by the Company typically vest over a four year period. Certain of the options are subject to acceleration of vesting in the event of certain change of control transactions. The options are exercisable from the date of grant for a period of ten years. For options granted prior to the Company’s IPO, the exercise price equaled the estimated fair value of the Common Stock as determined by the board of directors on the date of grant. For options granted subsequent to the Company’s IPO, the exercise price equaled the closing price of the Company’s stock on the Nasdaq Global Select Market on the date of grant.

Stock option activity at December 31, 2018 and changes during the year then ended are presented in the table and narrative below (in thousands, except share and per share data):

	Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Options outstanding at December 31, 2017		5,997,794		$	13.33		7.14	$	6,065
Granted		2,575,725			5.48
Exercised		(115,064	)		2.35
Canceled		(1,136,019	)		10.67
Options outstanding at December 31, 2018		7,322,436		$	11.16		7.45	$	5
Options exercisable at December 31, 2018		3,865,419		$	15.49		6.45	$	5

The aggregate intrinsic value in the table above represents the difference between the Company’s closing common stock price on the last trading day during the year ended December 31, 2018 and the exercise price of the options, multiplied by the number of in-the-money options. The total intrinsic value of options exercised in the years ended December 31, 2018 and 2017 was $0.4 million and $0.2 million, respectively. As of December 31, 2018, there was $13.4 million of total unrecognized stock-based compensation cost related to employee unvested stock options granted under the 2006 Plan and the 2013 Plan. The Company expects to recognize that cost over a remaining weighted-average period of 2.4 years.

Since the Company completed its IPO on March 25, 2013, it has not had sufficient historical data to support a calculation of volatility and expected life. As such, the Company has used a weighted-average volatility considering the Company’s own volatility and the volatilities of a representative group of publicly traded companies. For purposes of identifying similar entities, the Company selected a group of publicly traded life science/biotechnology companies based on their disease focus, stage of development, number of compounds in clinical trials and number of years as a publicly-traded company. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant, commensurate with the expected life assumption. The expected life of stock options granted represents the weighted-average period of time that stock options granted are expected to be outstanding determined using the simplified method for employee grants. For non-employee grants, the expected life is equal to the remaining contractual term. The expected life is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its employee population.

The Company estimates the fair value of each employee and director stock option award on the grant date using the Black-Scholes option-pricing model based on the following assumptions:

	Years Ended December 31,
	2018	2017
Volatility factor	91.45%-97.39%	89.24%-90.56%
Expected life (in years)	5.31-6.11	5.31-6.11
Risk-free interest rate	2.41%-3.04%	1.78%-2.18%
Dividend yield	0%	0%

Compensation cost for stock options and restricted stock units granted to employees is based on the estimated grant-date fair value and is recognized over the vesting period of the applicable option on a straight-line basis. Stock-based compensation expense related to stock options and restricted stock units granted to employees was $13.0 million and $12.0 million during the years ended December 31, 2018 and 2017, respectively.

Using the Black-Scholes option-pricing model, the weighted-average grant date fair values of options granted to employees for the years ended December 31, 2018 and 2017 was $4.18 and $3.37, respectively.

Stock-based compensation expense recognized in the Company’s consolidated statements of operations during the periods presented was as follows (in thousands):

	Year Ended December 31,
	2018		2017
Research and development	$	5,721	$	5,768
General and administrative		7,408		6,195
Total	$	13,129	$	11,963

	Year Ended December 31,
	2018		2017
Stock options	$	10,925	$	11,156
Restricted stock units		2,089		686
Employee stock purchase plan		115		121
Total	$	13,129	$	11,963

Restricted Stock Units

In April 2018, the Company granted restricted stock units to employees. These restricted stock units vest in quarterly increments over one to two years, subject to continued employment with the Company and had a grant date fair value of $3.04 per share, which was the closing price of the Company’s common stock on the date of grant.

In January 2018 and 2017, the Company issued to certain employees 284,000 and 175,000 restricted stock units, respectively, which vest based on service and performance conditions. None of these awards fully vested during years ended December 31, 2018 and 2017. Vesting of these awards is contingent on the occurrence of certain milestone events and fulfillment of any remaining service condition. As a result, the related compensation cost is recognized as an expense when achievement of the milestone is considered probable over the remaining requisite service period. During 2018, certain of the performance conditions were achieved or deemed probable of achievement, resulting in recognition of related compensation cost of $0.3 million.

The following table summarizes the restricted stock activity for the year ended December 31, 2018:

	Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2017		282,034		$	6.09
Granted		937,460			4.02
Cancelled		(70,526	)		5.07
Vested/Released		(68,528	)		8.47
Unvested at December 31, 2018		1,080,440			4.21

As of December 31, 2018, there was $1.1 million of total unrecognized stock-based compensation expense related to restricted stock units granted under the Plan. The expense is expected to be recognized over a weighted-average period of 1.0 year.

Employee Stock Purchase Plan

12 Months Ended

Dec. 31, 2018

Text Block [Abstract]

Employee Stock Purchase Plan

(8) Employee Stock Purchase Plan

The ESPP was approved by the Company’s stockholders on June 12, 2014 and allows the Company to sell an aggregate of 300,000 shares of common stock. The ESPP allows eligible employees to purchase common stock at a price per share equal to 85% of the lower of the fair market value of the common stock at the beginning or end of each period during the term of the ESPP. The offering periods are six months each from May to November and from November to May of each calendar year. Pursuant to the ESPP, the Company sold a total of 86,145 shares of common stock during the year ended December 31, 2018 under the ESPP at purchase prices of $3.15, and $1.62, respectively, which represented 85% of the closing price of the Company’s common stock on May 14, 2018, and November 14, 2018, respectively. Pursuant to the ESPP, the Company sold a total of 77,604 shares of common stock during the year ended December 31, 2017 under the ESPP at purchase prices of $3.43, and $5.10, respectively, which represented 85% of the closing price of the Company’s common stock on May 12, 2017, and November 14, 2017, respectively. The Company records stock-based compensation expense under the ESPP based on the fair value of the purchase rights using the Black-Scholes option pricing model. The total stock-based compensation expense recorded as a result of the ESPP was $115,000 and $121,000 during the years ended December 31, 2018 and 2017, respectively.

Debt Facility

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Debt Facility

(9) Debt Facility

On November 2, 2018, the Company entered into a loan and security agreement (the “Loan Agreement”) with Solar Capital Ltd., as collateral agent and lender, and the other lenders named therein (Solar Capital Ltd. and the other lenders collectively, the “Lenders”). The Lenders have agreed to make available to the Company term loans in an aggregate principal amount of up to $75.0 million under the Loan Agreement. The Company plans to use the proceeds of the term loans to support commercial launch of Xerava as well as for working capital and general corporate purposes. The Loan Agreement provides a term loan commitment of $50.0 million in two potential tranches: (i) a $30.0 million Term A loan facility funded on November 2, 2018 and (ii) a $20.0 million Term B loan facility to be funded at the request of the Company no later than October 31, 2020, subject to (A) the Company having unrestricted net cash proceeds of not less than $50 million from the issuance and sale of common stock and/or from other business activities and (B) the Company having product revenue greater than or equal to $14.0 million on a six month trailing basis prior to September 30, 2020. Both of these term loans have a maturity date of May 2, 2023. The Loan Agreement also provides access to an additional Term C loan facility in the amount of $25.0 million, to be funded at the Lenders’ sole discretion.

Borrowings under all three loan facilities bear interest at a floating per annum rate equal to the 1 Month LIBOR Rate plus 7.25%. The Company is permitted to make interest-only payments on the initial $30.0 million Term A loan for the fifteen (15) months following the funding date. The interest-only period can be extended by an additional nine (9) months subject to certain conditions being met, including a 12-month trailing revenue milestone of $8.5 million by December 31, 2019; and by an additional six (6) months if the Company has met certain other conditions, including a 6-month trailing revenue milestone of $14.0 million by September 30, 2020 and raising $50.0 million in new capital. The term of the combined facility will be 54 months, with repayment paid in equal monthly installments commencing at the end of the resulting interest-only period as outlined above through the end of the 54-month term.

The Company is obligated to pay a final fee equal to 4.00% of the aggregate amount of the term loans funded, to occur upon the earliest of (i) the maturity date, (ii) the acceleration of the term loans, and (iii) the prepayment of the term loans. The Company has the option to prepay all, but not less than all of the outstanding principal balance of the term loans under the Loan Agreement. If the Company prepays all or a portion of the term loans prior to the maturity date, it will pay the Lenders a prepayment penalty fee based on a percentage of the outstanding principal balance, equal to 3% if the payment occurs on or before 12 months after the initial funding date, 2% if the prepayment occurs more than 12 months after, but on or before 24 months after, the initial funding date, or 1% if the prepayment occurs more than 24 months after the initial funding date.

In connection with the Loan Agreement and the funding of the Term A loan facility, the Company issued to the Lenders warrants to purchase an aggregate of 414,365 shares of the Company’s common stock, equal to 3.00% of the term loan funded divided by the exercise price of $2.172. The Company is obligated to issue additional warrants to the Lenders in the event the Term B loan facility and/or the Term C loan facility is funded. Those warrants shall also be equal to 3.00% of the term loan funded. The warrants are exercisable at the option of the holder and the exercise price will be the lesser of (a) the 10-day trailing average of the Company’s common stock price, as determined as of the close of business day immediately prior to the funding date of the respective term loan, and (b) the Company’s common stock price, as determined as of the close of business day immediately prior to the funding date of the respective term loan. Each warrant will terminate 10 years from the date of its original issuance. The warrants were equity classified with a fair value of $0.8 million at issuance and recorded to additional paid in capital.

The Company’s obligations under the Loan Agreement are secured by a first priority security interest in substantially all of its assets. The Loan Agreement contains customary representations, warranties and covenants and also includes customary events of default, including payment defaults, breaches of covenants, change of control and a material adverse change default. The Company has agreed to maintain cash on hand at all times equal to $10.0 million plus an amount equal to 90 days aged accounts payable subject to certain exceptions, or it is in breach of the Loan Agreement.

Upon the occurrence of an event of default, a default interest rate of an additional 4.00% per annum may be applied to the outstanding loan balances, and the Lenders may declare all outstanding obligations immediately due and payable and exercise all of its rights and remedies as set forth in the Loan Agreement and under applicable law.

The Company recorded interest expense related to the loan facility of $624,000 for the year ended December 31, 2018. The fair value of the loan at December 31, 2018 approximates its face amount given the close proximity of execution to December 31, 2018.

The Company evaluated the accounting for the Loan Agreement and identified an embedded derivative related to repayment upon default, which it evaluated and deemed immaterial. The Company will reassess this conclusion at each reporting period.

Future principal debt payments on the loan payable are as follows (in thousands):

	December 31, 2018
2019	$	—
2020		8,462
2021		9,231
2022		9,231
2023		3,076
Total principal payments		30,000
Final fee due at maturity in 2023		1,200
Total principal and final fee payments		31,200
Unamortized debt issuance costs and final fee		(2,909	)
Loan payable, long term	$	28,291

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

(10) Income Taxes

The Company accounts for income taxes under ASC 740, Accounting for Income Taxes. Deferred income tax assets and liabilities are determined based upon differences between financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse.

Loss before income tax (benefit) provision consists of the following (in thousands):

	Year ended December 31,
	2018			2017
United States	$	(61,046	)	$	(94,748	)
Foreign		(11,112	)		(20,004	)
Total loss before income taxes	$	(72,158	)	$	(114,752	)

For the years ended December 31, 2018 and 2017 the Company did not have a current or deferred income tax expense or benefit.

A reconciliation of the Federal statutory tax rate of 21% to the Company’s effective income tax rate follows:

	Year ended December 31,
	2018			2017
Statutory tax rate		(21.00	)%		(34.00	)%
State taxes, net of federal benefits		(4.10	)%		(4.37	)%
Permanent differences		2.30	%		1.18	%
Credits		(1.80	)%		(0.96	)%
Intellectual property transfer		(3.80	)%		—
Change in valuation allowance		25.20	%		(11.04	)%
Foreign rate differential		3.20	%		5.93	%
Federal Rate Change - Tax Reform		—			43.26	%
Effective tax rate		—	%		—	%

On December 22, 2017, the Tax Cuts and Jobs Act ("the Act") was enacted in the United States. The Act reduces the U.S. federal corporate tax rate from 34% to 21%, requires companies to pay a one-time transition tax on earnings of certain foreign subsidiaries that were previously tax deferred and creates new taxes on certain foreign sourced earnings. For the year ended December 31, 2018, we recognized no transition tax and have not recorded any additional taxes on the outside basis difference of our foreign subsidiary as our investment in the foreign subsidiary is essentially permanent in duration. Determining the amount of unrecognized deferred tax liability is not practicable.

In connection with the Act, the Company remeasured certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21%. The remeasurement of the Company's deferred tax balance was primarily offset by application of its valuation allowance. As of December 31, 2018, the Company had completed its accounting for all of the tax effects of the enactment of the Act; including the effects on its existing deferred tax balances. The Company had not recognized any material adjustment to the provisional estimate that was previously recorded related to the Act.

As of December 31, 2018, the Company had federal net operating loss carryforwards of approximately $428.0 million and state net operating loss carryforwards of $395.6 million, which are available to reduce future taxable income. Federal net operating loss carryforwards of $383.2 million will expire are various dates through 2037. $44.9 million of the federal net operating loss carryforward can be carried forward indefinitely. The state net operating loss carryforward of $395.6 million will expire at various dates through 2038.

The Company also had federal tax credits of $8.4 million and state tax credits of $2.9 million, which may be used to offset future tax liabilities. The net operating loss (NOL) and tax credit carryforwards will expire at various dates through 2038.

The NOL and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. In addition, the Company has not, as yet, conducted a study of research and development (“R&D”) credit carryforwards. This study may result in an adjustment to the Company’s R&D credit carryforwards. Any adjustment as a result of such study would be fully offset by a decrease in the Company’s valuation allowance.

The principal components of the Company’s deferred tax assets are as follows (in thousands):

	Year ended December 31,
	2018			2017
Deferred tax assets:
Net operating loss carryforwards	$	114,097		$	102,942
Equity-based compensation		8,836			7,073
Accrued expenses		149			142
Depreciation		116			52
Start up costs		5			8
Intangibles		4,578			967
Research and development credits and carryforwards		10,649			9,079
Deferred tax assets		138,430			120,263
Less valuation allowance		(138,430	)		(120,263	)
Net deferred tax assets	$	—		$	—

ASC 740 requires a valuation allowance to reduce the deferred tax assets reported, if based on the weight of available evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. After consideration of all the evidence, both positive and negative, the Company has recorded a valuation allowance against its deferred tax assets at December 31, 2018 and 2017, respectively, because the Company’s management has determined that is it more likely than not that these assets will not be realized. The $18.2 million increase in the valuation allowance in 2018 primarily relates to the loss incurred by the Company in this period.

ASC 740 clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statement by prescribing the minimum recognition threshold and measurement of a tax position taken or expected to be taken in a tax return. The Company had gross tax-effected unrecognized tax benefits of $1.3 million and $1.1 million at December 31, 2018 and 2017, respectively. Unrecognized tax benefits represent tax positions for which reserves have been established. A full valuation allowance has been provided against the Company’s deferred tax assets, so that the effect of any unrecognized tax benefits would simply be to reduce the gross amount of the deferred tax asset and the corresponding valuation allowance. The Company anticipates that the amount of unrecognized tax benefits recorded will not change in the next twelve months.

As of December 31, 2018 and 2017, the Company had no accrued interest or penalties related to uncertain tax positions.

The aggregate changes in gross unrecognized tax benefits during the years ended December 31, 2018 and 2017 were as follows (in thousands):

	Year ended December 31,
	2018		2017
Balance at beginning of year	$	1,107	$	967
Increases for tax positions taken during current period		130		152
Increases for tax positions taken in prior periods		54		—
Decreases for tax positions taken during current period		—		(12	)
Decreases for tax positions taken in prior periods		—		—
Balance at end of year	$	1,291	$	1,107

The Company is currently open to examination under the statute of limitations by the Internal Revenue Service and state jurisdictions for the tax years ended 2015 through 2017. Carryforward tax attributes generated in years past may still be adjusted upon future examination if they have or will be used in a future period. The Company is currently not under examination by the Internal Revenue Service or any other jurisdictions for any tax years.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

(11) Commitments and Contingencies

Lease Commitments

On March 24, 2015, the Company amended its existing operating lease to expand its existing premises by an additional 13,711 square feet of office and laboratory space for a total of 29,610 square feet. The effective date of this amendment was April 1, 2015. On March 31, 2015, the Company canceled an existing sublease entered into in September 2014 covering 15,174 square feet of office and laboratory space.

On June 18, 2015, the Company further amended its existing operating lease to expand its leased premises by an additional 7,828 square feet of office and laboratory space for a total of 37,438 square feet. The lease for the additional office and laboratory space was effective as of August 1, 2015. In connection with the amendment, the lease term was extended from November 30, 2016 to November 30, 2019.

In the third quarter of 2016, the Company entered into a sublease with respect to a portion of its principal facilities with an unrelated third party. The term of the sublease expires in November 2019, with the sublessee obligated to pay rent to the Company that approximates the rent the Company is currently paying to its landlord with respect to such portion of its facility.

On November 29, 2018, the Company amended its existing operating lease to extend the lease term through November 30, 2022.

As of December 31, 2018, the aggregate minimum future rent payments under the lease agreement, net of the sublease agreement, are as follows (in thousands):

	December 31, 2018
2019		1,806
2020		1,875
2021		1,913
2022		1,785
Total minimum lease payments	$	7,379

The Company recorded $1.4 million and $1.4 million in rent expense for the years ended December 31, 2018 and 2017, respectively

Legal Proceedings

12 Months Ended

Dec. 31, 2018

Legal Proceedings Disclosure [Abstract]

Legal Proceedings

(13) Legal Proceedings

In January 2016 and March 2016, two securities class action lawsuits were filed against the Company, the Company’s chief executive officer, the Company’s former chief operating officer and the Company’s former chief financial officer, in the United States District Court for the District of Massachusetts. In May 2016, the court consolidated the two lawsuits and appointed lead plaintiffs and lead counsel. The lead plaintiffs filed a consolidated amended complaint in July 2016 and filed a second consolidated amended complaint in August 2016. The second amended complaint was brought on behalf of an alleged class of those who purchased the Company’s common stock between March 5, 2015 and September 8, 2015, and alleged claims arising under Sections 10 and 20 of the Exchange Act of 2934, as amended. The complaint generally alleged that the defendants violated the federal securities laws by, among other things, making material misstatements or omissions concerning IGNITE2. The complaint sought, among other relief, unspecified compensatory damages, attorneys’ fees and costs. In October 2016, the Company filed a motion to dismiss the second amended complaint in its entirety, which plaintiffs opposed. The Company’s motion to dismiss was granted by the United States District Court for the District of Massachusetts in May 2017. In July 2017 plaintiffs appealed this decision to the United States Court of Appeals for the First Circuit, or the First Circuit. In November 2017 plaintiffs withdrew their appeal to the First Circuit.

In July 2018, a purported securities class action lawsuit was filed against us, our chief executive officer, our chief scientific officer and the underwriters of our July 2017 public offering, in the United States District Court for the Southern District of New York. The complaint is brought on behalf of an alleged class of those who purchased our securities pursuant and/or traceable to our July and August 2017 public offering and those who purchased our securities between March 8, 2017 and February 13, 2018. The complaint purports to allege claims arising under Sections 10 and 20 of the Exchange Act of 1934, as amended, and Sections 11 and 15 of the Securities Act of 1933, as amended. The complaint generally alleges that the defendants violated the federal securities laws by, among other things, making material misstatements or omissions concerning IGNITE3. The complaint seeks, among other relief, unspecified compensatory damages, attorneys’ fees, and costs. The defendants have moved to transfer the lawsuit to the United States District Court for the District of Massachusetts. We believe we have valid defenses against these claims, and will engage in a vigorous defense of such litigation and therefore a loss is not probable as of December 31, 2018.

Quarterly Results (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Quarterly Results (Unaudited)

(14) Quarterly Results (Unaudited)

Three Months Ended

March 31,

2018

June 30,

2018

September 30,

2018

December 31,

2018

(in thousands, except per share data)

(unaudited)

Revenues:

Product revenues, net

—